cytochrome-c-t and Leukemia

Topics: Caspase 3; Cytochromes c; Humans; Leukemia; MicroRNAs; Morpholinos; Proto-Oncogene Proteins c-akt

Topics: Animals; Antineoplastic Agents; Apoptosis; Caspases; Cell Line, Tumor; Cell Survival; Cytochromes c; Drug Synergism; Flavonoids; Fluorouracil; Humans; Leukemia; Membrane Potential, Mitochondrial; Mice; Mitochondria; Reactive Oxygen Species; Signal Transduction

Guaiane-type sesquiterpene lactones are naturally occurring compounds which have attracted attention due to their array of biological activities. In this study, chlorinated guaianolides

Topics: Antineoplastic Agents; Apoptosis; Cytochromes c; Cytotoxins; Humans; Lactones; Leukemia; Poly(ADP-ribose) Polymerases; Sesquiterpenes, Guaiane; U937 Cells

Topics: Animals; Antineoplastic Agents, Alkylating; Apoptosis; Autophagy; B-Lymphocytes; Caspase 3; Caspase 8; Caspase 9; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Diterpenes; DNA Damage; Endoplasmic Reticulum Chaperone BiP; Epoxy Compounds; Leukemia; Lymphocyte Activation; Macrophages; Male; Medicine, Chinese Traditional; Membrane Potential, Mitochondrial; Mice; Mice, Inbred BALB C; Microscopy, Confocal; Phenanthrenes; Reactive Oxygen Species; Spleen; T-Lymphocytes; Transplantation, Homologous

Natural products isolated from marine environment are well known for their pharmacodynamic potential in diversity of disease treatments such as cancer or inflammatory conditions. Sea cucumbers are one of the marine animals of the phylum Echinoderm. Many studies have shown that the sea cucumber contains antioxidants and anti-cancer compounds. Chronic lymphocytic leukemia (CLL) is a disease characterized by the relentless accumulation of CD5

Topics: Aged; Aged, 80 and over; Animals; Antineoplastic Agents; Apoptosis; B-Lymphocytes; Case-Control Studies; Cell Survival; Cytochromes c; Drug Screening Assays, Antitumor; Female; Holothuria; Humans; Indian Ocean; Leukemia; Leukemia, Lymphocytic, Chronic, B-Cell; Male; Membrane Potential, Mitochondrial; Middle Aged; Mitochondria; Mitochondrial Swelling; Reactive Oxygen Species; Tumor Cells, Cultured

Doxorubicin (DOX) is a small molecular cytotoxic agent that can be transferred efficiently to cancer cells by nanocarriers. This anthracycline antibiotic serves as an effective anti-neoplastic drug against both hematological and solid malignancies. Here, we set out to assess the capacity of a novel doxorubicin - transferrin conjugate (DOX-TRF) to provoke apoptosis in human normal and leukemia cells through free radicals produced via a redox cycle of doxorubicin (DOX) when released from its conjugate.. After DOX-TRF exposure, we determined the time-course of apoptotic and necrotic events, the generation of reactive oxygen species (ROS), changes in mitochondrial membrane potential, as well as alterations in cytochrome c levels and intracellular calcium concentrations in human leukemia-derived cell lines (CCRF-CEM, K562 and its doxorubicin-resistant derivative K562/DOX) and normal peripheral blood-derived mononuclear cells (PBMC).. We found that DOX-TRF can induce apoptosis in all leukemia-derived cell lines tested, which was associated with morphological changes and decreases in mitochondrial membrane potential. In comparison to free DOX treated cells, we observed a time-dependency between a higher level of ROS generation and a higher drop in mitochondrial membrane potential, particularly in the doxorubicin-resistant cell line. In addition, we found that the apoptotic cell death induced by DOX-TRF was directly associated with a release of cytochrome c from the mitochondria and an increase in intracellular calcium level in all human leukemia-derived cell lines tested.. Our data indicate that DOX-TRF is considerably more cytotoxic to human leukemia cells than free DOX. In addition, we show that DOX-TRF can effectively produce free radicals, which are directly involved in apoptosis induction.

Topics: Adult; Apoptosis; Calcium; Cell Shape; Cytochromes c; Doxorubicin; Humans; Intracellular Space; K562 Cells; Leukemia; Leukocytes, Mononuclear; Male; Membrane Potential, Mitochondrial; Mitochondria; Reactive Oxygen Species; Transferrin; Young Adult

Oridonin, obtained from the traditional Chinese herbal medicine rabdosia rubescens, exerts potent antitumor activities in cancer cells. Valproic acid (VPA), as a potent histone deacetylase inhibitor (HDACI), also plays an important role in inhibition of proliferation of tumor cells. However, there are no reports so far on the cooperation between oridonin and VPA for anti-leukemic effect. Therefore, in the present study, we undertook experiments to determine whether lower concentration of oridonin in conjunction with lower concentration of VPA would produce even more encouraging synergistic effect than each of them alone, and to clarify its molecular mechanism. The results demonstrated that the lower concentration of oridonin in combination with lower concentration of VPA synergistically inhibited the proliferation of HL-60 cells, and induced obvious caspase-dependent apoptosis through activation of the intrinsic apoptosis pathway, which is involved in the downregulation of Bcl-2/Bax ratio, release of cytochrome c to cytosol and caspase-9 activation, as well as through the extrinsic apoptosis pathway mediated by Fas/FasL and caspase-8 activation. In addition, MAPK signaling pathway was also involved in apoptosis induced by oridonin plus VPA. Furthermore, the combination treatment in vivo remarkably reduced the xenograft tumor size and triggered tumor cell apoptosis. Taken together, the novel combination of oridonin plus VPA exerted synergistic anti-proliferative and apoptosis-inducing effects on human myeloid leukemia cells, and may serve as a potential promising anti-leukemia strategy.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Caspase 8; Caspase 9; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Diterpenes, Kaurane; Drug Therapy, Combination; Fas Ligand Protein; HL-60 Cells; Humans; Leukemia; Mice; Mice, Inbred BALB C; Mice, Nude; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; Valproic Acid

The aim of the present study was to investigate the anticancer effects of resveratrol‑4‑O‑D-(2'‑galloyl)-glucopyranoside (REG) on leukemia and the mechanism underlying its effects. Three leukemia cell lines (HL‑60, Jurkat and U937) were used in this study. A Cell Counting kit‑8 assay was performed to evaluate the anti‑proliferative activity of REG on leukemia cell lines, and flow cytometric analysis was used to detect REG‑induced apoptosis. In addition, western blot analysis was conducted to detect the levels of apoptosis‑related proteins including, cytochrome c, cleaved (c)‑caspases‑3 and ‑9, B‑cell lymphoma 2 (Bcl‑2) and Bcl‑2‑associated protein x (Bax). Finally, a HL‑60 cell xenograft model in nude mice was used to evaluate the antitumor effect of REG on leukemia in vivo. The present results indicated that REG can significantly inhibit the proliferation of HL‑60, Jurkat and U937 cell lines in a concentration‑ and time‑dependent manner. The half maximal inhibitory concentration values were 38.4, 49.1 and 48.2 µg/ml for HL‑60, Jurkat and U937 cells, respectively. Furthermore, flow cytometric analysis demonstrated that REG can induce the apoptosis of HL‑60 cells, as well as increase the levels of cytochrome c, c‑caspases‑3 and ‑9, and Bax, as well as downregulate the expression of Bcl‑2. In vivo, REG was found to possess a marked anticancer effect on leukemia. In combination, the present results indicated that REG exerts significant anticancer effects on leukemia in vivo and in vitro through the induction of apoptosis.

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; bcl-2-Associated X Protein; Caspase 3; Caspase 9; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Flow Cytometry; Glucosides; Leukemia; Mice, Nude; Proto-Oncogene Proteins c-bcl-2; Resveratrol; Stilbenes; Xenograft Model Antitumor Assays

The Korean prostrate spurge Euphorbia supina (Euphorbiaceae family) has been used as a folk medicine in Korea against a variety of ailments such as bronchitis, hemorrhage, jaundice and multiple gastrointestinal diseases. Polyphenols from Korean E. supina (PES) which include quercetin and kaempferol derivatives have anticancer properties. Hence, we investigated the anticancer effects of PES on U937 human leukemic cells. Firstly, PES significantly inhibited the proliferation of U937 cells in a dose-dependent manner. PES induced accumulation of the sub-G1 DNA content (apoptotic cell population), apoptotic bodies and chromatin condensation and DNA fragmentation in the U937 cells. PES also induced activation of caspase-3, -8 and -9, subsequent cleavage of PARP, and significantly suppressed XIAP, cIAP-1 and cIAP-2 in a dose-dependent manner. Furthermore, PES activated Bid, and induced the loss of mitochondrial membrane potential (MMP, ΔΨm) along with upregulation of pro-apoptotic proteins (Bax and Bad), and downregulation of anti-apoptotic proteins (Bcl-2 and Bcl-xL) and cytochrome c release. The Fas receptor was upregulated by PES in a dose-dependent manner, suggesting that the extrinsic pathway was also involved in the PES-induced apoptosis. Moreover, the PES-induced apoptosis was at least in part associated with extracellular signal-regulated kinase (ERK) activation in the U937 human leukemic cells. This study provides evidence that PES may be useful in the treatment of leukemia.

Topics: Antineoplastic Agents; Apoptosis; Baculoviral IAP Repeat-Containing 3 Protein; bcl-2-Associated X Protein; bcl-Associated Death Protein; BH3 Interacting Domain Death Agonist Protein; Caspase 3; Caspase 8; Caspase 9; Cell Line, Tumor; Cell Proliferation; Cytochromes c; DNA Fragmentation; Enzyme Activation; Euphorbia; Extracellular Signal-Regulated MAP Kinases; G1 Phase Cell Cycle Checkpoints; Humans; Inhibitor of Apoptosis Proteins; Leukemia; MAP Kinase Signaling System; Membrane Potential, Mitochondrial; Phosphoinositide-3 Kinase Inhibitors; Phytochemicals; Poly(ADP-ribose) Polymerases; Polyphenols; Republic of Korea; U937 Cells; Ubiquitin-Protein Ligases; X-Linked Inhibitor of Apoptosis Protein

Human autoimmune diseases are caused by a variety of factors, such as environmental chemicals, including para-nonylphenol. Macrophages play many critical roles in the regulation of immunity and the progression of autoimmune diseases. However, little information is available regarding the effects of para-nonylphenol on cellular signaling pathways and the death of these cells in vitro. Here, we show that very high concentrations of para-nonylphenol (50-100 μM) induce apoptosis in U937 human monocyte leukemia cells in a dose-dependent manner.. Cell viability was judged using the trypan blue exclusion method. FACS analysis for DNA fragmentation was conducted, cellular signaling pathways were evaluated using western blot analysis, and caspase activity was measured by using substrates. U937 cells were differentiated by PMA.. Treatment with > 50 μM para-nonylphenol induced apoptosis in U937 monocyte cells and MCF- 7 and MDA-MB231 human breast cancer cells. We found cytochrome c release from the mitochondria to the cytoplasm, DNA fragmentation, and decreased expression of anti-apoptotic protein Bcl-XL. Caspase 3 and 9 were induced, but caspase 1 and 3-inhibitor treatment suppressed apoptosis. Para-nonylphenol decreased the levels of activated AKT and increased the levels of activated JNK/SAPK at 15 min after treatment. Furthermore, with PMA treatment, U937 cells were differentiated into a macrophage-like phenotype and showed attenuated cell death against para-nonylphenol.. As this assay system is simple and rapid, it may represent a useful artificial tool to clarify the signaling pathways of apoptotic cell death in human monocytes in vitro.

Topics: Apoptosis; Caspases; Cell Death; Cell Line, Tumor; Cytochromes c; Humans; Leukemia; MCF-7 Cells; Mitochondria; Monocytes; Phenols; Phosphorylation; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; U937 Cells

To analyze the causative mechanisms in refractory leukemia cells.. Vascular endothelial growth factor (VEGF) blood plasma concentrations in 35 de novo, 6 relapse, 20 remission leukemia patients and 10 healthy kids were determined via ELISA analyses. Transcription levels of the VEGF receptors (VEGFR) Fms-like tyrosine kinase-1 (Flt-1) and kinase-domain insert containing receptor (KDR) were determined in participants' leucocytes with RT-PCR. Apoptosis rates as well as Cyt-C and Caspase-3 expression was determined in Jurkat, Jurkat(Bcl-2), healthy and recurrent leukemia leukocytes with and without VP-16 applications via flow cytometry. Total Akt (t-Akt) expression and its phosphorylation (p-AKT) status in leukocytes of the participants were analyzed with western blots.. Healthy children and the remission group had the lowest blood plasma VEGF concentrations (91.16±41.34 vs. 135.80±111.28 pg/ml), followed by de novo leukemia patients (362.49±195.68 pg/ml-494.19±186.23 pg/ml) and relapse patients (574.37±278.45 pg/ml) (P<0.01). The same trend was statistically significant visible for Flt-1 and KDR expressions in leukocytes of the participants. Stable Bcl-2 overexpression led to reduced apoptosis rates as well as Cyt-C and Caspase-3 expressions in Jurkat cells after VP-16 application, which was similar in leucocytes of remission patients. In contrast to no phosphorylation in healthy children, Akt was phosphorylated in 10% remission samples, 30% de novo leukemia samples and in 67% of recurrent leukemia leucocytes.. High VEGF plus VEGFR expression and AKT phosphorylation are highest in leukocytes of remission patients, suggesting VEGF signaling as a cause of reduced apoptosis susceptibility upon treatments.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Biomarkers, Tumor; Case-Control Studies; Caspase 3; Child; Child, Preschool; Cytochromes c; Drug Resistance, Neoplasm; Enzyme-Linked Immunosorbent Assay; Female; HL-60 Cells; Humans; Infant; Jurkat Cells; K562 Cells; Leukemia; Leukocytes; Male; Phosphorylation; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Remission Induction; Reverse Transcriptase Polymerase Chain Reaction; Treatment Outcome; Up-Regulation; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-1; Vascular Endothelial Growth Factor Receptor-2

20(S)-Ginsenoside Rh2 (GRh2) and ginsenoside Rg3 (GRg3) are members of the protopanaxadiol family and have been investigated for possible chemopreventive activity. This study explored the biological and apoptotic mechanisms induced by 20(S)-GRh2 in human acute leukaemia line-Reh cells. Reh cells were treated with different concentration of 20(S)-GRh2 in vitro. Cell viability was determined by Cell Counting Kit-8 and Annexin V/7-AAD assays. Mitochondrial membrane potential (MMP) was examined through JC-1 staining. Activation of caspases associated with the mitochondria-mediated apoptosis pathway was determined by Western blot. We observed that survival of Reh cells decreased after exposure to 20(S)-GRh2 in a concentration-dependent manner. Moreover, 20(S)-GRh2 can induce mitochondria depolarization of Reh cells as evident in the shift in JC-1 fluorescence from red to green. In addition, 20(S)-GRh2 induced the release of mitochondrial cytochrome c and activation of caspase-9 and caspase-3 in Reh cells. These results indicate that 20(S)-GRh2 could induce apoptosis through the mitochondrial pathway, demonstrating its potential as a chemotherapeutic agent for leukaemia therapy.

Topics: Annexin A5; Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 3; Caspase 9; Cell Line, Tumor; Cytochromes c; Dose-Response Relationship, Drug; Drugs, Chinese Herbal; Ginsenosides; Humans; Leukemia; Membrane Potential, Mitochondrial; Mitochondria; Panax; Phytotherapy; Signal Transduction

Chalcones, naturally occurring open-chain flavonoids abundant in plants, have demonstrated anticancer activity in multiple tumor cells. In a previous work, the potential anticancer activity of three naphthylchalcones named R7, R13 and R15 was shown. In this study, the mechanism of actions of these chalcones was originally shown. The chalcones presented concentration and time-dependent cytotoxicity. To determine the type of cell death induced by chalcones, we assessed a series of assays including measurements of the caspase-8, -9 and -12 activities, expression of important apoptosis-related genes and proteins, changes in the cell calcium concentration and cytochrome c release. The activities of caspase-8, -9 and -12 increased after the treatment of L1210 cells with the three compounds. Chalcones R7 and R13 induced an increase of pro-apoptotic proteins Bax, Bid and Bak (only chalcone R13), as well as a decrease in anti-apoptotic Bcl-2 expression. These chalcones also induced an increase in Fas and a decrease in p21 and p53 expression. Chalcone R15 seems to act by a different mechanism to promote cell death, as it did not change the mitochondrion-related proteins, nor did it induce the cytochrome c release. All compounds induced an increase in cell calcium concentration and an increase in CHOP expression, which together with an increase in caspase-12 activity, suggest that chalcones could induce an endoplasmic reticulum (ER) stress. Taken together, these results suggest that chalcones induce apoptosis by different pathways, being an interesting strategy to suggest for cancer therapy.

Topics: Animals; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Calcium; Cell Cycle; Cell Death; Cell Line, Tumor; Chalcones; Cyclin-Dependent Kinase Inhibitor p21; Cytochromes c; Endoplasmic Reticulum Stress; fas Receptor; Gene Expression; Leukemia; Mice; NIH 3T3 Cells; Tumor Suppressor Protein p53; Vero Cells

The purpose of this study was to investigate how proliferation and apoptosis in human leukemia U937 cells are affected by four hydroxycinnamic acid derivatives (HCADs) in corn (Zea mays L.) bran: p-coumaric (CA), ferulic acids (FA), dicoumaroylputrescine (DCP), and diferuloylputrescine (DFP). Of the four HCADs, DFP dose dependently exerted the strongest cytotoxic effect and induction of apoptosis in the U937 cells. In addition, DFP induced distinct morphological changes characteristic of cellular apoptosis, such as chromatin condensation, apoptotic bodies, and DNA fragmentations. The DFP-induced apoptosis was also associated with released cytochrome c in the cytosol with activation of caspase 3, together with the downregulation of anti-apoptotic proteins, including XIAP and cIAP2, Bcl-2, and Mcl-1. Finally, the DFP-induced apoptosis was a cell-specific response in leukemia cells, as compared with those of other cancer cells, such as Caki, HT29, SK-Hep1, and MDA-MB231. Thus, these results suggest that DFP may be useful as a potential source of natural antileukemic agents.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 3; Cell Proliferation; Coumaric Acids; Cytochromes c; DNA Fragmentation; Dose-Response Relationship, Drug; Gene Expression; Humans; Leukemia; Microscopy, Fluorescence; Putrescine; Seeds; U937 Cells; Zea mays

One polysaccharide (SRP) was purified from Sanguisorbae radix by DEAE-cellulose-52 anion-exchange and Sephacryl S-400 gel filtration chromatography. The aim of this study was to evaluate the anticancer efficacy of SRP on human leukemia HL-60 cells in vitro and unveil the underlying mechanisms. Our results showed that SRP was able to suppress the proliferation of HL-60 cells in a dose-dependent manner by the mechanism involved in the induction of apoptosis. The increase in SRP-induced apoptosis was correlated with a rapid and sustained loss of mitochondrial transmembrane potential (ΔΨm) and a release of cytochrome c from the mitochondria into the cytosol. Furthermore, Western blot and RT-PCR analysis revealed that the protein and mRNA levels of antiapoptotic Bcl-2 were downregulated, whereas those of pro-apoptotic Bax were upregulated. Besides, caspase-9 and caspase-3 were activated, while caspase-8 was intact. Additionally, the apoptotic cells by SRP were significantly inhibited by a caspase-3 inhibitor (z-DEVD-fmk) or a caspase-9 inhibitor (Z-LETD-FMK), demonstrating the important role of caspase-9 and -3 in the process. Taken together, these findings provided evidence that SRP induced the apoptosis of HL-60 cells through an intrinsic mitochondria-mediated signaling pathway and SRP may be a promising chemotherapeutic agent for treatment of leukemia.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Caspases; Cell Proliferation; Cytochromes c; Enzyme Activation; Genes, bcl-2; HL-60 Cells; Humans; Leukemia; Membrane Potential, Mitochondrial; Polysaccharides; Sanguisorba

Hypericum japonicum Thunb. ex Murray is widely used as an herbal medicine for the treatment of hepatitis and tumours in China. However, the molecular mechanisms of its effects are unclear. Our previous research showed that extracts of H. japonicum can induce apoptosis in leukaemia cells. We also previously systematically analysed and isolated the chemical composition of H. japonicum.. The fluorescence polarisation experiment was used to screen for inhibitors of Bcl-2 proteins which are proved as key proteins in apoptosis. The binding mode was modelled by molecular docking. We investigated the proliferation attenuating and apoptosis inducing effects of active compound on cancer cells by MTT assay and flow cytometry analysis. Activation of caspases were tested by Western blot. A broad-spectrum caspase inhibitor Z-VAD-FMK was used to investigate the caspases-dependence. In addition, co-immunoprecipitation was performed to analyse the inhibition of heterodimerization between anti-apoptotic Bcl-2 proteins with pro-apoptotic proteins. Moreover, in vivo activity was tested in a mouse xenograph tumour model.. Jacarelhyperol A (Jac-A), a characteristic constituent of H. japonicum, was identified as a potential Bcl-2 inhibitor. Jac-A showed binding affinities to Bcl-xL, Bcl-2, and Mcl-1 with Ki values of 0.46 μM, 0.43 μM, and 1.69 μM, respectively. This is consistent with computational modelling results, which show that Jac-A presents a favorable binding mode with Bcl-xL in the BH3-binding pocket. In addition, Jac-A showed potential growth inhibitory activity in leukaemia cells with IC50 values from 1.52 to 6.92 μM and significantly induced apoptosis of K562 cells by promoting release of cytochrome c and activating the caspases. Jac-A also been proved that its effect is partly caspases-dependent and can disrupt the heterodimerization between anti-apoptotic Bcl-2 proteins with pro-apoptotic proteins. Moreover, Jac-A dose-dependently inhibited human K562 cell growth in a mouse xenograph tumour model with low toxicity.. In this study, a characteristic constituent of H. japonicum, Jac-A, was shown to induce apoptosis in leukaemia cells by mediating the Bcl-2 proteins. Therefore, we propose a new lead compound for cancer therapy with a low toxicity, and have provided evidence for using H. japonicum as an anti-cancer herb.

Topics: Animals; Antineoplastic Agents; Apoptosis; bcl-X Protein; Binding Sites; Caspases; Cell Line, Tumor; Cytochromes c; Disease Models, Animal; Drug Screening Assays, Antitumor; Female; Humans; Inhibitory Concentration 50; K562 Cells; Leukemia; Mice; Models, Molecular; Molecular Conformation; Protein Binding; Protein Multimerization; Proto-Oncogene Proteins c-bcl-2; Xanthenes; Xenograft Model Antitumor Assays

The WW domain-containing oxidoreductase (WWOX) gene which encompasses the common human fragile site FRA16D has been proposed as a putative tumor suppressor gene, and loss of WWOX expression has been found in several types of solid cancer. As the role of WWOX in human leukemia has not yet been fully elucidated, the present study examined the expression of WWOX in patients with different types of leukemia as well as in leukemia-derived cell lines. Based on the data, WWOX mRNA (WWOX) and protein (Wwox) were significantly reduced or absent in the leukemia patients as well as in the cell lines. In addition, a recombinant expression vector, pGC-FU-WWOX, was constructed and transfected WWOX cDNA into Jurkat cells (acute T-lymphoblastic leukemia) and K562 cells (chronic myeloid leukemia in erythroid crisis) which all lack endogenous Wwox. In vitro experiments indicated that restoration of Wwox in Jurkat and K562 cells significantly suppressed proliferation and colony formation. Of note, apoptosis was also induced by Wwox restoration. Furthermore, we traced the mechanisms underlying this process and found that Wwox restoration could trigger the mitochondrial pathway in leukemia. Our data provide evidence that WWOX exerts a role as a tumor suppressor gene in leukemia, possibly by inhibiting proliferation and promoting apoptosis via the mitochondrial pathway.

Topics: Apoptosis; bcl-2-Associated X Protein; Case-Control Studies; Caspase 3; Caspase 9; Cell Proliferation; Cytochromes c; Gene Expression; Genes, Tumor Suppressor; Humans; Jurkat Cells; K562 Cells; Leukemia; Oxidoreductases; Proto-Oncogene Proteins c-bcl-2; Tumor Suppressor Proteins; WW Domain-Containing Oxidoreductase

RU486 (mifepristone) exerts an anticancer effect on cancer cells via induction of apoptosis. However, the molecular mechanisms are not fully understood. Here, we investigated the effect of RU486 on the apoptosis of U937 human leukemia cells. RU486 markedly increased apoptosis in U937 cells as well as in MDA231 human breast carcinoma, A549 human lung adenocarcinoma epithelial and HCT116 human colorectal carcinoma cells. RU486 increased dose-dependent release of mitochondrial cytochrome c, and reduced the mitochondrial membrane potential (MMP, Δψm) in RU486-treated U937 cells. We also found that overexpression of Bcl-2 completely blocked RU486-mediated apoptosis. However, reactive oxygen species signaling had no effect on RU486-induced apoptosis. RU486 increased the phosphorylation of p38 MAPK and JNK, but p38 MAPK only was associated with RU486-mediated apoptosis. Taken together, RU486 induces apoptosis through reduction in the mitochondrial membrane potential and activation of p38 MAPK in U937 human leukemia cells.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Apoptosis; Breast Neoplasms; Cell Line, Tumor; Colorectal Neoplasms; Cytochromes c; Enzyme Activation; Female; HCT116 Cells; Hormone Antagonists; Humans; Leukemia; Lung Neoplasms; Lymphoma; MAP Kinase Signaling System; Membrane Potential, Mitochondrial; Mifepristone; p38 Mitogen-Activated Protein Kinases; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Receptors, Glucocorticoid; U937 Cells

Melatonin is a naturally occurring indoleamine synthesized in the pineal gland that exhibits an extensive repertoire of biological activities. An increasing number of studies indicate that melatonin protects normal cells, while it reducing cancer cell proliferation. In this study, we investigated the effect of melatonin on the growth of the human leukemia cells and found that it efficiently reduced the number of cells in a concentration- and time-dependent manner. Thus, incubation with the indoleamine increased the percentage of cells with a hypodiploid DNA content, augmented the number of annexin V-positive cells, and also provoked ultrastructural changes that are features of apoptotic cell death. Evaluation of caspases revealed that caspase-3, caspase-6, caspase-7, and caspase-9, but not caspase-8 and caspase-2, were quickly activated (3-6 hr). The increase in the activity of these proteases was associated with up-regulation of the pro-apoptotic factor Bax and also with the release of cytochrome c from mitochondria. Pretreatment of the cells with the general caspase inhibitor z-VAD-fmk, reduced melatonin-induced apoptosis, but it did not block cell death suggesting that melatonin activates an alternative cell death modality in the absence of caspase activity. Thus, the activation of caspases was preceded by a fast (<30 min) increase in reactive oxygen species (ROS). Rotenone and antimycin A reduced the levels of ROS stimulated by melatonin, indicating that the complex I and the complex III of the mitochondrial electron transport chain are important sources of these chemical species. However, the role of ROS in melatonin-induced cell death remains elusive because anti-oxidants that were shown to decrease ROS levels (glutathione, N-acetyl-l-cysteine and Trolox) were unable to abrogate melatonin-induced cell death.

Topics: Antioxidants; Apoptosis; bcl-2-Associated X Protein; Caspase 9; Cell Line, Tumor; Cytochromes c; Drug Evaluation, Preclinical; Humans; Leukemia; Melatonin; Reactive Oxygen Species

The present study investigated possible mechanisms on the apoptosis induction of human leukemic cells by fucoidan, a sulfated polysaccharide found in marine algae. Fucoidan treatment of cells resulted in inhibition of growth and induction of apoptosis, as measured by 3-(4,5-dimetylthiazol-2-yl)-2,5-diphenyl-tetrazolium (MTT) assay, fluorescence microscopy, DNA fragmentation, and flow cytometry analysis. The increase in apoptosis was associated with the proteolytic activation of caspases, Bid cleavage, insertion of pro-apoptotic Bax into the mitochondria, release of cytochrome c from mitochondria to cytosol, and loss of mitochondria membrane potential (MMP) in U937 cells. However, apoptosis induced by fucoidan was attenuated by caspase inhibitors, indicating that fucoidan-induced apoptosis was dependent on the activation of caspases. Furthermore, fucoidan treatment effectively activated the p38 mitogen-activated protein kinase (MAPK) and p38 MAPK inhibitor, SB203580, and significantly reduced fucoidan-induced apoptosis through inhibition of Bax translocation and caspases activation, suggesting that the activation of p38 MAPK may play a key role in fucoidan-induced apoptosis. In addition, the authors found fucoidan-induced significantly attenuated in Bcl-2 overexpressing U937 cells, and pretreatment with fucoidan and HA 14-1, a small-molecule Bcl-2 inhibitor, markedly increased fucoidan-mediated apoptosis in Bcl-2 overexpressing U937 cells. Our findings imply that we may attribute some of the biological functions of p38 MAPK and Bcl-2 to their ability to inhibit fucoidan-induced apoptosis.

Topics: Apoptosis; bcl-2-Associated X Protein; Caspases; Cell Line, Tumor; Cytochromes c; Cytosol; HL-60 Cells; Humans; K562 Cells; Leukemia; Membrane Potential, Mitochondrial; Mitochondria; p38 Mitogen-Activated Protein Kinases; Polysaccharides; Proto-Oncogene Proteins c-bcl-2; U937 Cells

The nuclease activity and the cytotoxicity toward human leukemia cancer cells of iron complexes, [Fe(HPClNOL)Cl2]NO3 (1), [Cl(HPClNOL)Fe(μ-O)Fe(HPClNOL)Cl]Cl2·2H2O (2), and [(SO4)(HPClNOL)Fe(μ-O)Fe(HPClNOL)(SO4)]·6H2O (3) (HPClNOL=1-(bis-pyridin-2-ylmethyl-amino)-3-chloropropan-2-ol), were investigated. Each complex was able to promote plasmid DNA cleavage and change the supercoiled form of the plasmid to circular and linear ones. Kinetic data revealed that (1), (2) and (3) increase the rate of DNA hydrolysis about 278, 192 and 339 million-fold, respectively. The activity of the complexes was inhibited by distamycin, indicating that they interact with the minor groove of the DNA. The cytotoxic activity of the complexes toward U937, HL-60, Jukart and THP-1 leukemia cancer cells was studied employing 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), fluorescence and electronic transmission microscopies, flow cytometry and a cytochrome C release assay. Compound (2) has the highest activity toward cancer cells and is the least toxic for normal ones (i.e. peripheral blood mononuclear cells (PBMCs)). In contrast, compound (1) is the least active toward cancer cells but displays the highest toxicity toward normal cells. Transmission electronic microscopy indicates that cell death shows features typical of apoptotic cells, which was confirmed using the annexin V-FITC/PI (fluorescein isothiocyanate/propidium iodide) assay. Furthermore, our data demonstrate that at an early stage during the treatment with complex (2) mitochondria lose their transmembrane potential, resulting in cytochrome C release. A quantification of caspases 3, 9 (intrinsic apoptosis pathway) and caspase 8 (extrinsic apoptosis pathway) indicated that both the intrinsic (via mitochondria) and extrinsic (via death receptors) pathways are involved in the apoptotic stimuli.

Topics: Apoptosis; Caspases; Cell Line, Tumor; Cell Survival; Coordination Complexes; Cytochromes c; Deoxyribonucleases; DNA; DNA, Superhelical; Enzyme Activation; HL-60 Cells; Humans; Hydrogen-Ion Concentration; Hydrolysis; Iron Compounds; Jurkat Cells; Kinetics; Leukemia; Leukocytes, Mononuclear; Membrane Potential, Mitochondrial; Microscopy, Electron, Transmission; Mitochondria; Signal Transduction; U937 Cells

Terpinen-4-ol, a monoterpene, is found as the main component of essential oil extracts from many plants. In this study apoptotic and autophagic types of cell death induced by terpinen-4-ol and associated mechanisms were investigated in human leukemic HL-60 cells.. The cytotoxicity of human leukemic U937 and HL-60 cells was determined by MTT assay. Cytochrome c release, expression of Bax, Bcl-2, Bcl-xl and cleaved Bid were determined by Western blotting. Cell morphology was examined under a transmission electron microscope. LC3-I/II, ATG5 and Beclin-1 levels were detected by immunoblotting.. Terpinen-4-ol exhibited cytotoxicity to human leukemic HL-60 but not U937 cells. The apoptotic response to terpinen-4-ol in HL-60 cells was due to induction of cytochrome c release from mitochondria and cleavage of Bid protein after the stimulation of caspase-8. There was a slightly decrease of Bcl-xl protein level. The characteristic cell morphology of autophagic cell death was demonstrated with multiple autophagosomes in the cytoplasm. At the molecular level, the results from Western blot analysis showed that terpinen-4-ol significantly induced accumulation of LC3-I/II, ATG5 and Beclin-1, regulatory proteins required for autophagy in mammalian cells.. Terpinen-4-ol induced-human leukemic HL-60 cell death was via both autophagy and apoptosis.

Topics: Apoptosis; Autophagy; bcl-2-Associated X Protein; bcl-X Protein; BH3 Interacting Domain Death Agonist Protein; Blotting, Western; Caspase 8; Cytochromes c; Humans; Leukemia; Mitochondria; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Terpenes; Tumor Cells, Cultured

3β,16β,17α-Trihydroxycholest-5-en-22-one 16-O-(2-O-4-methoxybenzoyl-β-D-xylopyranosyl)-(1→3)-2-O-acetyl-α-L-arabinopyranoside (OSW-1) is a natural product with potent antitumor activity against various types of cancer cells, but the exact mechanisms of action remain to be defined. In this study, we showed that OSW-1 effectively killed leukemia cells at subnanomolar concentrations through a unique mechanism by causing a time-dependent elevation of cytosolic Ca(2+) prior to induction of apoptosis. A mechanistic study revealed that this compound inhibited the sodium-calcium exchanger 1 on the plasma membrane, leading to an increase in cytosolic Ca(2+) and a decrease in cytosolic Na(+). The elevated cytosolic Ca(2+) caused mitochondrial calcium overload and resulted in a loss of mitochondrial membrane potential, release of cytochrome c, and activation of caspase-3. Furthermore, OSW-1 also caused a Ca(2+)-dependent cleavage of the survival factor GRP78. Inhibition of Ca(2+) entry into the mitochondria by the uniporter inhibitor RU360 or by cyclosporin A significantly prevented the OSW-1-induced cell death, indicating the important role of mitochondria in mediating the cytotoxic activity. The extremely potent activity of OSW-1 against leukemia cells and its unique mechanism of action suggest that this compound may be potentially useful in the treatment of leukemia.

Topics: Biological Products; Calcium; Calcium Channels; Calpain; Caspase 3; Cell Death; Cell Line, Tumor; Cholestenones; Cyclosporine; Cytochromes c; Cytosol; Drug Screening Assays, Antitumor; Endoplasmic Reticulum; Endoplasmic Reticulum Chaperone BiP; Enzyme Activation; Extracellular Space; Heat-Shock Proteins; Homeostasis; Humans; Leukemia; Lymphoma; Membrane Potential, Mitochondrial; Mitochondria; Saponins; Sodium-Calcium Exchanger; Thapsigargin; Time Factors

The present study investigated possible mechanisms of apoptosis induction of U937 human leukemic cells by 7,8-dihydroxyflavone hydrate (7,8-DHF), a member of the flavonoid family and a recently identified tyrosine kinase receptor B (TrkB) agonist. 7,8-DHF treatment of U937 cells resulted in inhibition of growth and induction of apoptosis as measured by MTT assay, fluorescence microscopy, DNA fragmentation, and flow cytometry analysis. 7,8-DHF-induced apoptosis in U937 cells was correlated with the up-regulation of death receptor related protein levels and down-regulation of anti-apoptotic IAP family proteins. The increase in apoptosis was also associated with proteolytic activation of caspases, Bid cleavage, insertion of pro-apoptotic Bax into the mitochondria and release of cytochrome c from mitochondria to cytosol. Furthermore, it was found that Bcl-2 overexpression markedly protected U937 cells from 7,8-DHF-induced apoptosis by restoring activation of caspases. In addition, 7,8-DHF treatment effectively activated the mitogen-activated protein kinases (MAPK), and inhibitors of extracellular-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), but not p38 MAPK, which significantly reduced 7,8-DHF-induced apoptosis. Taken together, our results indicate that the JNK and ERK pathways, and modulation of Bcl-2 family proteins were key regulators of apoptosis in response to 7,8-DHF in U937 cells.

Topics: Apoptosis; Caspases; Cell Proliferation; Cytochromes c; Flavones; Humans; Leukemia; MAP Kinase Signaling System; Proto-Oncogene Proteins c-bcl-2; Receptor, trkB; Receptors, Death Domain; Signal Transduction; U937 Cells

We studied the effect of riccardin D, a macrocyclic bisbibenzyl, which was isolated from the Chinese liverwort plant, on human leukemia cells and the underlying molecular mechanism. Riccardin D had a significant antiproliferative effect on human leukemia cell lines HL-60, K562 and its multidrug resistant (MDR) counterpart K562/A02 cells, but showed no effect on the topoisomerase-II-deficient HL-60/MX2 cells, as measured by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. The pBR322 DNA relaxation assay revealed that riccardin D selectively inhibited the activity of topoisomerase II (topo II). The suppression of topo II activity by riccardin D was stronger than that of etoposide, a known topo II inhibitor. After treatment with riccardin D, nuclear extracts of leukemia K562 and K562/A02 cells left the majority of pBR322 DNA in a supercoiled form. Further examination showed that riccardin D effectively induced HL-60, K562 and K562/A02 apoptosis as evidenced by externalization of phosphatidylserine and formation of DNA ladder fragments. The activation of cytochrome c, caspase-9, caspase-3 and cleaved poly ADP-ribose polymerase (PARP) was also enhanced, as estimated by Western blot analysis. By contrast, riccardin D was unable to induce apoptosis in the topoisomerase-II-deficient HL-60/MX2 cells, indicating that the induction of apoptosis by riccardin D was due to the inhibition of topo II activity. In addition, riccardin D was able to significantly decrease P-glycoprotein (P-gp) expression in K562/A02 cells. Taken together, our data demonstrate that riccardin D is a novel DNA topo II inhibitor which can induce apoptosis of human leukemia cells and that it has therapeutic potential for both regular and MDR strains of leukemia cells.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1; Caspase 3; Caspase 9; Cell Proliferation; Cytochromes c; DNA Fragmentation; DNA Topoisomerases, Type II; DNA, Superhelical; Dose-Response Relationship, Drug; Drug Resistance, Multiple; Drug Resistance, Neoplasm; HL-60 Cells; Humans; K562 Cells; Leukemia; Phenyl Ethers; Phosphatidylserines; Poly(ADP-ribose) Polymerases; Stilbenes; Time Factors; Topoisomerase II Inhibitors

Two novel dichlorophenyl urea compounds, SR4 and SR9, were synthesized in our laboratory and evaluated for anti-cancer activities. Specifically, we investigated the antiproliferative properties of these new compounds on promyelocytic HL-60 leukemia cells by analyzing their effects on cell differentiation, cell cycle progression and apoptosis. SR4 and SR9 were both cytotoxic to HL-60 cells in a dose-and time-dependent manner, with IC(50) of 1.2 μM and 2.2 μM, respectively, after 72 h treatment. Both compounds strongly suppressed growth of HL-60 cells by promoting cell cycle arrest at the G0/G1 transition, with concomitant decrease in protein levels of cyclins D1 and E2 and cyclin-dependent kinases (CDK 2 and CDK 4), and increased protein expression of CDK inhibitors p21(WAF1/Cip1) and p27(Kip1). In addition, either compounds induce cell differentiation as detected by increased NBT staining and expression of CD11b and CD14. Treatment with SR compounds also promoted mitochondrial-dependent apoptosis as confirmed by Annexin V-FITC double staining, DNA fragmentation, increased expression of caspase 3, 7 and 9, cytochrome c release, PARP degradation, and collapse in mitochondrial membrane potential (ΔΨ(MT)). Collectively, these results provide evidence that SR4 and SR9 have the potential for the treatment of human leukemia and merit further investigation as therapeutic agents against other types of cancer.

Topics: Apoptosis; Blotting, Western; Caspases; Cell Cycle Checkpoints; Cell Cycle Proteins; Cell Differentiation; Cell Proliferation; Cell Shape; Cytochromes c; DNA Fragmentation; Dose-Response Relationship, Drug; Enzyme Activation; G1 Phase Cell Cycle Checkpoints; HL-60 Cells; Humans; Leukemia; Membrane Potential, Mitochondrial; Monocytes; Phenylurea Compounds; Poly(ADP-ribose) Polymerases; Proteolysis; Time Factors

The synthetic caged Garcinia xanthone, cluvenone, has potent and selective cytotoxicity against numerous cancer cell lines including those that are multi-drug resistant. The direct target of this structurally and functionally unique agent is unknown and that of the parent natural product, gambogic acid (GA), presently in clinical trials, is not yet entirely clear. For the first time, using fluorescently labeled GA (GA-Bodipy), we determined that GA-Bodipy localized in mitochondria and was effectively displaced by cluvenone in competition experiments indicating that the direct target of cluvenone resided in mitochondria and was shared by GA. In agreement with these findings, treatment of HeLa cells with cluvenone or GA resulted in disruption of mitochondrial morphology within 4 h. Furthermore, experiments using the potential sensitive JC-1 dye demonstrated that cells treated with 1 μM cluvenone for 1 h had significant loss of MMP compared to control cells. Examination of Cyt c levels in leukemia cells treated with 1 μM cluvenone resulted in a 4-fold increase in levels of both cytosolic and mitochondrial Cyt c. In agreement with Cyt c release, caspase 9 activity was increased 2.6-fold after treatment of cells for 5 h with 1 μM cluvenone. Remarkably, the caspase-9 inhibitor, Z-LEHD-FMK, blocked cluvenone-induced apoptosis in a dose-dependent manner with apoptosis being completely blocked by 10 μM of the inhibitor. In conclusion, cluvenone, an agent with potent cytotoxicity against multi-drug resistant tumor cells, has direct targets in mitochondria thus setting precedence for drug discovery efforts against these targets in the treatment of refractory cancers.

Topics: Apoptosis; Caspase 9; Cell Line, Tumor; Cytochromes c; Drug Resistance, Neoplasm; HeLa Cells; Humans; Leukemia; Mitochondria; Xanthones

In this study, we investigated the functional role of Akt and c-jun-NH(2)-kinase (JNK) signaling cascades in apigenin-induced apoptosis in U937 human leukemia cells and anti-leukemic activity of apigenin in vivo. Apigenin induced apoptosis by inactivation of Akt with a concomitant activation of JNK, Mcl-1 and Bcl-2 downregulation, cytochrome c release from mitochondria, and activation of caspases. Constitutively active myristolated Akt prevented apigenin-induced JNK, caspase activation, and apoptosis. Conversely, LY294002 and a dominant-negative construct of Akt potentiated apigenin-induced apoptosis in leukemia cells. Interruption of the JNK pathway showed marked reduction in apigenin-induced caspase activation and apoptosis in leukemia cells. Furthermore, in vivo administration of apigenin resulted in attenuation of tumor growth in U937 xenografts accompanied by inactivation of Akt and activation of JNK. Attenuation of tumor growth in U937 xenografts by apigenin raises the possibility that apigenin may have clinical implications and can be further tested for incorporating in leukemia treatment regimens.

Topics: Animals; Apigenin; Apoptosis; Caspases; Cell Line, Tumor; Chromones; Cytochromes c; Down-Regulation; Humans; JNK Mitogen-Activated Protein Kinases; Jurkat Cells; Leukemia; Mice; Mice, Nude; Mitochondria; Morpholines; Myeloid Cell Leukemia Sequence 1 Protein; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; RNA Interference; RNA, Small Interfering; Signal Transduction; U937 Cells; Xenograft Model Antitumor Assays

Juglone, a major chemical constituent of Juglans mandshruica Maxim, is a promising anticancer agent that has shown a strong activity against cancer cells in vitro. Our previous study showed that juglone inhibited the proliferation of HL-60 cells with an IC50 value ∼8 μM. To further explore the proapoptotic mechanism of juglone, we investigated the role of the reactive oxygen species (ROS) in the apoptosis induced by juglone in HL-60 cells. The generation of ROS was about 2 to 8-fold as compared to control cell after treatment with juglone (2, 4 and 8 μM) for 24 h. The glutathione (GSH) depletion was consistent with ROS generation after treatment with juglone. Reversal of apoptosis in antioxidants (NAC and catalase) pretreated cells indicated the involvement of ROS in juglone-induced apoptosis. The cleavage of PARP and procaspase-3 and -9, loss of mitochondrial membrane potential (△Ψm), and release of cytochrome c (Cyt c) and Smac induced by juglone were significantly blocked by NAC. NAC also prevented the inhibition the phosphorylation of Akt and mTOR proteins by juglone. Collectively, these results indicated that ROS played a significant role in the apoptosis induced by juglone in human leukemia cell HL-60.

Topics: Acetylcysteine; Annexin A5; Antioxidants; Apoptosis; Caspases; Cell Division; Cytochromes c; Enzyme Activation; Glutathione; HL-60 Cells; Humans; Juglans; Leukemia; Membrane Potentials; Naphthoquinones; Reactive Oxygen Species

Polyphenols are natural compounds widely present in fruits and vegetables, which have antimutagenic and anticancer properties. The aim of the present study was to determine the anticancer effect of a polyphenol-rich Aronia melanocarpa juice (AMJ) containing 7.15 g/L of polyphenols in the acute lymphoblastic leukemia Jurkat cell line, and, if so, to clarify the underlying mechanism and to identify the active polyphenols involved. AMJ inhibited cell proliferation, which was associated with cell cycle arrest in G(2)/M phase, and caused the induction of apoptosis. These effects were associated with an upregulation of the expression of tumor suppressor p73 and active caspase 3, and a downregulation of the expression of cyclin B1 and the epigenetic integrator UHRF1. AMJ significantly increased the formation of reactive oxygen species (ROS), decreased the mitochondrial membrane potential and caused the release of cytochrome c into the cytoplasm. Treatment with intracellular ROS scavengers prevented the AMJ-induced apoptosis and upregulation of the expression of p73 and active caspase 3. The fractionation of the AMJ and the use of identified isolated compounds indicated that the anticancer activity was associated predominantly with chlorogenic acids, some cyanidin glycosides, and derivatives of quercetin. AMJ treatment also induced apoptosis of different human lymphoblastic leukemia cells (HSB-2, Molt-4 and CCRF-CEM). In addition, AMJ exerted a strong pro-apoptotic effect in human primary lymphoblastic leukemia cells but not in human normal primary T-lymphocytes. Thus, the present findings indicate that AMJ exhibits strong anticancer activity through a redox-sensitive mechanism in the p53-deficient Jurkat cells and that this effect involves several types of polyphenols. They further suggest that AMJ has chemotherapeutic properties against acute lymphoblastic leukemia by selectively targeting lymphoblast-derived tumor cells.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 3; CCAAT-Enhancer-Binding Proteins; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cytochromes c; DNA-Binding Proteins; Humans; Jurkat Cells; Leukemia; Lymphocytes; Membrane Potential, Mitochondrial; Mitochondria; Nuclear Proteins; Oxidation-Reduction; Photinia; Plant Extracts; Polyphenols; Reactive Oxygen Species; Tumor Protein p73; Tumor Suppressor Proteins; Ubiquitin-Protein Ligases

A series of alkyl α/β-(1→6)-diglucopyranosides 1-12 were synthesized and assessed for cytotoxicity against HL-60, U937, Molt-3 and MCF-7 cancer cell lines. The menthyl derivatives displayed strong cytotoxic properties showing IC(50) values between 6 and 16 μM. Furthermore, we demonstrated that the selected synthetic (+)-menthyl β-(1→6)-diglucopyranoside 5 induces apoptotic cell death in human leukemia cells through a mechanism that involves activation of multiple caspases. Cell death was completely prevented by the non-specific caspase inhibitor z-VAD-fmk and found to be associated with the release of cytochrome c, an increase in the expression of Bax levels and a decrease in the generation of reactive oxygen species.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; bcl-2-Associated X Protein; Caspases; Cell Line, Tumor; Cytochromes c; Disaccharides; HL-60 Cells; Humans; Leukemia; Reactive Oxygen Species

Leukemia, one of the causes of cancer-related death in humans, is an aggressive malignancy via the rapid growth of abnormal white blood cells. The aim of this study was to determine the anti-leukemia effect of glycyrrhizic acid (GA) on a mouse leukemia cell line, WEHI-3. GA, an active compound in Glycyrrhiza glabra, has been proven to induce cytotoxic effects in many cancer cell lines. In the current study, we investigated the effects of GA in mouse leukemia cells in vitro. The results indicated that GA induced morphological changes, G0/G1 phase arrest, apoptosis and DNA damage in WEHI-3 cells as determined by phase contrast microscopy, DAPI-staining, flow cytometry and comet assay. The results from the flow cytometric assay showed that GA increased ROS levels, reduced the mitochondrial membrane potential (ΔΨm) and stimulated caspase-3 activity in WEHI-3 cells. GA regulated the intrinsic and extrinsic apoptosis-associated protein expression which was determined by western blotting. In addition, endoplasmic reticulum (ER) stress responses were observed in GA-treated WEHI-3 cells. GA promoted the trafficking of apoptosis-inducing factor (AIF), cytochrome c and endonuclease G (Endo G) in WEHI-3 cells. Based on this evidence, GA-triggered apoptosis occurs through the death receptor, mitochondria-mediated and ER stress multiple signaling pathways.

Topics: Animals; Apoptosis; Apoptosis Inducing Factor; Caspase 3; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Survival; Cytochromes c; DNA Damage; Endodeoxyribonucleases; Endoplasmic Reticulum Stress; Glycyrrhizic Acid; Leukemia; Membrane Potential, Mitochondrial; Mice; Mitochondria; Protein Transport; Reactive Oxygen Species; Receptors, Death Domain

Gypenosides (Gyp), found in Gynostemma pentaphyllum Makino, have been used as folk medicine for centuries and have exhibited diverse pharmacological effects, including antileukemia effects in vitro and in vivo. In the present study, Gyp were used to examine effects on cell viability, cell cycle, and induction of apoptosis in vitro. They were administered in the diet to mice injected with WEHI-3 cells in vivo.. Effects of Gyp on WEHI-3 cells were determined by flow cytometric assay and Western blotting.. Gyp inhibited the growth of WEHI-3 cells. These effects were associated with the induction of G0/G1 arrest, morphological changes, DNA fragmentation, and increased sub-G1 phase. Gyp promoted the production of reactive oxygen species, increased Ca(2+) levels, and induced the depolarization of the mitochondrial membrane potential. The effects of Gyp were dose and time dependent. Moreover, Gyp increased levels of the proapoptotic protein Bax, reduced levels of the antiapoptotic proteins Bcl-2, and stimulated release of cytochrome c, AIF (apoptosis-inducing factor), and Endo G (endonuclease G) from mitochondria. The levels of GADD153, GRP78, ATF6-α, and ATF4-α were increased by Gyp, resulting in ER (endoplasmic reticular) stress in WEHI-3 cells. Oral consumption of Gyp increased the survival rate of mice injected with WEHI-3 cells used as a mouse model of leukemia.. Results of these experiments provide new information on understanding mechanisms of Gyp-induced effects on cell cycle arrest and apoptosis in vitro and in an in vivo animal model.

Topics: Activating Transcription Factor 4; Activating Transcription Factor 6; Animals; Apoptosis; Apoptosis Regulatory Proteins; Calcium; Cell Line, Tumor; Cytochromes c; Endodeoxyribonucleases; Endoplasmic Reticulum; Endoplasmic Reticulum Chaperone BiP; G1 Phase; Gynostemma; Heat-Shock Proteins; Leukemia; Male; Membrane Potential, Mitochondrial; Mice; Mice, Inbred BALB C; Plant Extracts; Reactive Oxygen Species; Resting Phase, Cell Cycle; Transcription Factor CHOP

Quercetin, a naturally occurring flavonoid abundant in fruits and vegetables, has been demonstrated as a multipotent bioflavonoid with great potential for the prevention and treatment of cancer. Apoptosis is thought to be an important response to most chemotherapeutic agents in leukemia cells. However, the underlying mechanism of induction of apoptosis by quercetin involving epigenetic regulation is poorly understood. In the present study, by evaluation of fragmentation of DNA, poly (ADP-ribose) polymerase (PARP) and procaspases, we found that quercetin was able to induce apoptosis of human leukemia HL-60 cells in a dose-dependent manner. Quercetin triggered the extrinsic apoptosis pathway through activation of caspase-8 and induction of Bid cleavage, Bax conformation change and cytochrome c release. Furthermore, quercetin induced Fas ligand (FasL) expression involving activation of the extracellular signal-regulated kinase (ERK) and Jun N-terminus kinase (JNK) signaling pathways. In addition to activation of c-Jun, quercetin increased histone H3 acetylation which resulted in the promotion of the expression of FasL. Quercetin exhibited potential for the activation of histone acetyltransferase (HAT) and the inhibition of histone deacetyltransferase (HADC), both of which contributed to histone acetylation. However, only the activation effect on HAT was associated with the ERK and JNK pathway. These results demonstrated that quercetin induced FasL-related apoptosis by transactivation through activation of c-jun/AP-1 and promotion of histone H3 acetylation in HL-60 cells.

Topics: Acetylation; Antioxidants; Apoptosis; bcl-2-Associated X Protein; BH3 Interacting Domain Death Agonist Protein; Caspase 8; Cytochromes c; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Fas Ligand Protein; Histone Acetyltransferases; Histones; HL-60 Cells; Humans; Leukemia; Quercetin

Artemisinin, the active principle of the Chinese medicinal herb Artemisia annua, and its derivatives (i.e. dihydroartemisinin, DHA) were reported to exhibit anti-tumor activity both in vitro and in vivo. The purpose of the present study was to investigate the functional role of Mitogen-Activated Protein Kinase (MEK)/Extracellular signal-regulated protein Kinase (ERK) signaling cascade in dihydroartemisinin (DHA)-induced apoptosis in human leukemia cells in vitro and anti-leukemic activity in vivo. Human leukemia cells were treated with DHA in dose- and time-dependent manners, after which apoptosis, caspase activation, Mcl-1 expression, and cell signaling pathways were evaluated. Parallel studies were performed in AML and ALL primary human leukemia cells. In vivo anti-leukemic activity mediated by DHA was also investigated using U937 xenograft mouse model. Exposure of DHA resulted in a pronounced increase in apoptosis in both transformed and primary human leukemia cells but not in normal peripheral blood mononuclear cells. DHA-induced apoptosis was accompanied by caspase activation, cytochrome c release, Mcl-1 down-regulation, as well as MEK/ERK inactivation. Pretreatment with MEK inhibitor PD98059, which potentiated DHA-mediated MEK and ERK inactivation, intensified DHA-mediated apoptosis. Conversely, enforced expression of a constitutively active MEK1 attenuated DHA-induced apoptosis. Furthermore, DHA-mediated inhibition of tumor growth of mouse U937 xenograft was associated with induction of apoptosis and inactivation of ERK. The findings in the present study showed that DHA-induced apoptosis in human leukemia cells in vitro and exhibited an anti-leukemic activity in vivo through a process that involves MEK/ERK inactivation, Mcl-1 down-regulation, culminating in cytochrome c release and caspase activation.

Topics: Animals; Antineoplastic Agents; Apoptosis; Artemisinins; Caspases; Cytochromes c; Extracellular Signal-Regulated MAP Kinases; Flavonoids; Humans; Leukemia; MAP Kinase Kinase Kinases; Mice; Myeloid Cell Leukemia Sequence 1 Protein; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; U937 Cells; Xenograft Model Antitumor Assays

Rhizomes of Alpinia galanga (Linn.) or 'Kha' in Thai are used in food and as folk medicine in South and Southeast Asia. The aims of this study were to identify the mechanism of cell death of human leukemic HL-60 and U937 cells induced by 4'-hydroxycinnamaldehyde (4'-HCA) isolated from A. galanga. 4'-HCA was cytotoxic to both cell lines in a dose-dependent manner (p<0.05) as demonstrated by MTT assay. Apoptosis induced by 4'-HCA was demonstrated by a variety of methods: visualization of propidium iodide (PI)-stained cells under fluorescence microscope, detection of subdiploid cells by PI-staining and flow cytometry, and assay of active caspase-3 using a specific fluorogenic substrate. 4'-HCA-treated cells (10 and 50 μg/ml for 4 h) showed significant increase in reactive oxygen species production and decreased mitochondrial transmembrane potential as detected by dichlorohydrofluorescein diacetate and 3,3'-dihexyloxacarbocyanine iodide respectively, together with flow cytometry. The apoptotic death involved cytochrome c release, increase in Bax level and concomitant decreases in levels of Bcl-2 and Bcl-xL (using Western blotting), and elevation in cytosolic and mitochondrial Ca²⁺ contents (using compartment-specific fluorescent Ca2+ dyes). These results indicate that 4'-HCA induces apoptosis of human leukemic cell through a combination of mitochondrial and ER stress pathways.

Topics: Alpinia; Apoptosis; bcl-2-Associated X Protein; bcl-X Protein; Blotting, Western; Caspases; Cell Proliferation; Cinnamates; Cytochromes c; Endoplasmic Reticulum; Humans; Leukemia; Membrane Potential, Mitochondrial; Mitochondria; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Tumor Cells, Cultured

Flavonoids are naturally occurring polyphenolic compounds and are among the most promising anticancer agents. Here we demonstrate that the flavonoid derivative astragalin heptaacetate (AHA) induces cell death. This was prevented by the non-specific caspase inhibitors z-VAD-fmk and Q-VD-OPH, and reduced by the selective caspase-4 inhibitor z-LEVD-fmk. AHA-induced cell death was found to be: (i) associated with the release of cytochrome c, (ii) suppressed by the overexpression of Bcl-x(L), (iii) amplified by inhibition of extracellular signal-regulated kinases (ERKs) 1/2 and c-jun NH(2)-terminal kinases/stress activated protein kinases (JNK/SAPK) signaling, and (iv) completely abrogated by the free-radical scavenger N-acetyl-l-cysteine.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Caspase Inhibitors; Caspases; Cell Death; Cell Proliferation; Cysteine Proteinase Inhibitors; Cytochromes c; Glycosides; HL-60 Cells; Humans; Kaempferols; Leukemia; MAP Kinase Signaling System; Proto-Oncogene Proteins c-bcl-2; Quinolines

Tocotrienols (Toc3) have been suggested to possess anticancer effects besides antioxidant and antiinflammatory effects. Previous studies have demonstrated that Toc3 induce apoptosis in epithelial carcinoma. However, the effects of Toc3 on malignant hematopoietic cells have not yet been thoroughly investigated. We investigated Toc3-induced apoptosis in human hematological cancer cell lines. α-, δ-, and γ-Toc3 induced concentration-dependent apoptosis, and γ-Toc3 demonstrated more effective induction than the other Toc3 derivatives in HL-60 cells. γ-Toc3 may have induced apoptosis by activation of the caspase cascade, cytochrome c (Cyt.c) release, Bid cleavage, and mitochondorial membrane depolarization in HL-60, NB-4, Raji, and SY-5Y cells. Furthermore, 10-30 μM γ-Toc3 showed cytotoxicity for leukemic cells from various patients regardless of lymphoblastic, myeloblastic, or relapsed leukemia, but the cytotoxic effect was weak in normal mononuclear cells, interestingly. γ-Toc3 may have a role in cancer prevention and potential for treating hematological malignancies.

Topics: Adolescent; Antineoplastic Agents, Phytogenic; Apoptosis; Apoptosis Regulatory Proteins; BH3 Interacting Domain Death Agonist Protein; Bone Marrow Cells; Caspases; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; Cells, Cultured; Child; Child, Preschool; Chromans; Cytochromes c; DNA Fragmentation; Female; Hematologic Neoplasms; Humans; Infant; Leukemia; Male; Membrane Potential, Mitochondrial; Mitochondria; Neoplasm Proteins; Vitamin E

Although cancers are characterized by the deregulation of multiple signalling pathways, most current anticancer therapies involve the modulation of a single target. Because of the enormous biological diversity of cancer, strategic combination of agents targeted against the most critical of those alterations is needed. Due to their complex nature, plant products interact with numerous targets and influence several biochemical and molecular cascades. The interest in further development of botanical drugs has been increasing steadily and the FDA recently approved the first new botanical prescription drug. The present study is designed to explore the potential antileukemic properties of Hemidesmus indicus with a view to contributing to further development of botanical drugs. Hemidesmus was submitted to an extensive in vitro preclinical evaluation.. A variety of cellular assays and flow cytometry, as well as a phytochemical screening, were performed on different leukemic cell lines. We have demonstrated that Hemidesmus modulated many components of intracellular signaling pathways involved in cell viability and proliferation and altered the protein expression, eventually leading to tumor cell death, mediated by a loss of mitochondrial transmembrane potential and increased Bax/Bcl-2 ratio. ADP, adenine nucleotide translocator and mitochondrial permeability transition pore inhibitors did not reverse Hemidesmus-induced mitochondrial depolarization. Hemidesmus induced a significant [Ca(2+)](i) raise through the mobilization of intracellular Ca(2+) stores. Moreover, Hemidesmus significantly enhanced the antitumor activity of three commonly used chemotherapeutic drugs (methotrexate, 6-thioguanine, cytarabine). A clinically relevant observation is that its cytotoxic activity was also recorded in primary cells from acute myeloid leukemic patients.. These results indicate the molecular basis of the antileukemic effects of Hemidesmus and identify the mitochondrial pathways and [Ca(2+)](i) as crucial actors in its anticancer activity. On these bases, we conclude that Hemidesmus can represent a valuable tool in the anticancer pharmacology, and should be considered for further investigations.

Topics: Aged; Aged, 80 and over; Apoptosis; Calcium; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cells, Cultured; Cytochromes c; Female; Flow Cytometry; Hemidesmus; HL-60 Cells; Humans; Leukemia; Male; Middle Aged; Plant Extracts

The novel chrysin analog 8-bromo-7-methoxychrysin (BrMC) has been reported to induce apoptosis of various cancer cell lines. Arsenic trioxide (ATO) treatment induces clinical remission in acute promyelocytic leukemia patients. The combination of ATO with other agents has been shown to improve therapeutic effectiveness in vitro and in vivo. In this report, the mechanism of apoptosis induced by treatment with ATO alone or in combination with BrMC was studied in U937, HL-60, and Jurkat cells. Our results demonstrated that BrMC cooperated with ATO to induce apoptosis in human leukemia cells. This co-treatment caused mitochondrial transmembrane potential dissipation and stimulated the mitochondrial apoptotic pathway, as evidenced by cytochrome c release, down-regulation of X-linked inhibitor of apoptosis (XIAP) and Bcl-XL, and up-regulation of Bax. BrMC alone or in combination with ATO, decreased Akt phosphorylation as well as intracellular reduced glutathione (GSH) content. The thiol antioxidant N-acetylcysteine and exogenous GSH restored GSH content and attenuated apoptosis induced by co-treatment with ATO plus BrMC. In contrast, the non-thiol antioxidant butylated hydroxyanisole and mannitol failed to do so. These findings suggest that GSH depletion explains at least in part the potentiation of ATO-induced apoptosis by BrMC.

Topics: Acetylcysteine; Antineoplastic Agents; Apoptosis; Arsenic Trioxide; Arsenicals; bcl-2-Associated X Protein; bcl-X Protein; Blotting, Western; Cell Survival; Cytochromes c; Dose-Response Relationship, Drug; Drug Synergism; Flavonoids; Glutathione; HL-60 Cells; Humans; Intracellular Space; Jurkat Cells; Leukemia; Mitochondria; Oxides; Phosphorylation; Proto-Oncogene Proteins c-akt; Time Factors; U937 Cells; X-Linked Inhibitor of Apoptosis Protein

Because tumor necrosis factor-alpha (TNF-alpha) is well-known to induce inflammatory responses, thus its clinical use is limited in cancer treatment. Rosmarinic acid (RA), a naturally occurring polyphenol flavonoid, has been reported to inhibit TNF-alpha-induced NF-kappaB activation in human dermal fibroblasts. However, the precise mechanisms of RA have not been well elucidated in TNF-alpha-mediated anti-cancer therapy. In this study, we found that RA treatment significantly sensitizes TNF-alpha-induced apoptosis in human leukemia U937 cells through the suppression of nuclear transcription factor-kappaB (NF-kappaB) and reactive oxygen species (ROS). Activation of caspases in response to TNF-alpha was markedly increased by RA treatment. However, pretreatment with the caspase-3 inhibitor, z-DEVD-fmk, was capable of significantly restoring cell viability in response to combined treatment. RA also suppressed NF-kappaB activation through inhibition of phosphorylation and degradation of IkappaBalpha, and nuclear translocation of p50 and p65. This inhibition was correlated with suppression of NF-kappaB-dependent anti-apoptotic proteins (IAP-1, IAP-2, and XIAP). RA treatment also normalized TNF-alpha-induced ROS generation. Additionally, ectopic Bcl-2 expressing U937 reversed combined treatment-induced cell death, cytochrome c release into cytosol, and collapse of mitochondrial potential. These results demonstrated that RA inhibits TNF-alpha-induced ROS generation and NF-kappaB activation, and enhances TNF-alpha-induced apoptosis.

Topics: Active Transport, Cell Nucleus; Antineoplastic Agents; Antioxidants; Apoptosis; Caspase Inhibitors; Caspases; Cell Survival; Cinnamates; Cysteine Proteinase Inhibitors; Cytochromes c; Depsides; Dose-Response Relationship, Drug; Hep G2 Cells; Humans; I-kappa B Proteins; Inhibitor of Apoptosis Proteins; Leukemia; Membrane Potential, Mitochondrial; NF-kappa B; NF-kappa B p50 Subunit; NF-KappaB Inhibitor alpha; Oxidative Stress; Phosphorylation; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Recombinant Proteins; Rosmarinic Acid; Signal Transduction; Transcription Factor RelA; Tumor Necrosis Factor-alpha; U937 Cells

A growing body of evidence suggests the inhibition of NFkappaB as a strategy to induce cell death in tumor cells. In this work, we evaluated the effects of the pharmacological NFkappaB inhibitors BAY117082 and MG132 on leukemia cells apoptosis. BAY117082 and MG132 presented potent apoptotic effects compared to inhibitors of MAPKs, EGFR, PI3K/Akt, PKC and PKA signaling pathways. Non-tumor peripheral blood cells were insensitive to BAY117082 and MG132 apoptotic effects. BAY117082 and MG132-induced apoptosis was dependent on their ability to increase ROS as a prelude to mitochondria membrane potential (MMP) depolarization, permeability transition pore opening and cytochrome c release. Antioxidants blocked MG132 and BAY117082 effects on ROS, MMP and cell death. Although apoptotic markers as phosphatidylserine externalization, chromatin condensation and sub-G1 were detected in BAY117082-treated cells, caspases activation did not occur and apoptosis was insensitive to caspase inhibitors, suggesting a caspase-independent mechanism. In contrast, MG132 induced classical apoptosis through ROS-mitochondria and subsequent caspase-9/caspase-3 activation. At sub-apoptotic concentrations, BAY117082 and MG132 arrested cells in G2/M phase of the cell cycle and blocked doxorubicin-induced NFkappaB, which sensitized doxorubicin-resistant cells. Data suggest that the NFkappaB inhibitors MG132 and BAY117082 are potential anti-leukemia agents.

Topics: Antibiotics, Antineoplastic; Antineoplastic Agents; Apoptosis; Caspases; Cell Proliferation; Cytochromes c; Dose-Response Relationship, Drug; Doxorubicin; Drug Resistance, Neoplasm; Enzyme Activation; Humans; Jurkat Cells; K562 Cells; Leukemia; Leupeptins; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; NF-kappa B; Nitriles; Reactive Oxygen Species; Sulfones; Time Factors; U937 Cells

Scorpion venom possesses protein toxins having numerous biological activities, some of which are potentially anticancerous. Previously we had reported antiproliferative activity of the venom of Indian black scorpion, Heterometrus bengalensis Koch. Here we have isolated and purified a novel protein named Bengalin (72kDa) from the venom, responsible for antiproliferative and apoptogenic activities against human leukemic cells U937 (histiocytic lymphoma) and K562 (chronic myelogenous leukemia). N-terminal sequence of first 20 amino acids of Bengalin was G-P-L-T-I-L-H-I-N-D-V-H-A-A/R-F-E-Q/G-F/G-N-T. Bengalin induced cell growth inhibition at IC(50) values of 3.7 and 4.1 microg/ml for U937 and K562 cells respectively did not significantly affect normal human lymphocytes. Inhibition of U937 and K562 cell proliferation occurred by apoptosis as evidenced from damaged nuclei, cell cycle arrest at sub G1 phase, increase of early apoptotic cells, augmentation of DNA fragmentation and also a reduction of telomerase activity. Further insights revealed that Bax:Bcl2 ratio was elevated after Bengalin treatment. Moreover Bengalin elicited loss of mitochondrial membrane potential (MMP) which commenced cytochrome c release in cytosol, decreased heat shock protein (HSP) 70 and 90 expression, activated caspase-9, caspase-3 and induced poly(ADP-ribose) polymerase (PARP) cleavage. We have also determined that HSP70 and 90 inhibitions correlated with Bengalin induced antiproliferation, caspase-3 upregulation, apoptogenesis and increased DNA fragmentation. These results hypothesize that Bengalin might provide a putative molecular mechanism for their anticancer effect on human leukemic cells which might be mediated by mitochondrial death cascade. Inhibition of HSPs might also play a crucial role in induction of apoptosis.

Topics: Amino Acid Sequence; Animals; Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Caspase 3; Caspase 9; Cytochromes c; G1 Phase; Heat-Shock Proteins; HSP70 Heat-Shock Proteins; HSP90 Heat-Shock Proteins; Humans; India; K562 Cells; Leukemia; Membrane Potential, Mitochondrial; Mitochondria; Molecular Sequence Data; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins c-bcl-2; Scorpion Venoms; U937 Cells

The plant Typhonium flagelliforme (TF), commonly known as 'rodent tuber' in Malaysia, is often used as traditional remedy for cancer, including leukemia.. We had previously identified morphologically that the linoleic acid rich fraction (DCM/F7) from the tubers of this plant induces selective anti-proliferative effects and apoptosis in CEMss cells. In this present study, we subjected the same DCM/F7 fraction to cell based activity analyses in order to determine the possible mechanism of cell death in leukemic CEMss cells in vitro.. Extraction of Typhonium flagelliforme tuber has done and fractionation has been done by vacuum liquid column chromatography. The anti-proliferative activity was assayed using MTT and the apoptosis detection was done by Annexin V and DNA laddering assay. Colorimetric caspase assay and immunoblot analysis were employed to detect the expression of protein associated with cell death. Cell cycle analysis was done using flow cytometry.. We found that the cancer inhibitory effect of the DCM/F7 fraction in CEMss cells was 3 ± 0.08 μg/ml (IC(50)). An early apoptotic induction in CEMss cells was observed by Annexin V assay, which showed a clear dose-dependent DNA fragmentation being observed in gel electrophoresis at 10 and 20 μg/ml. The DCM/F7 fraction at 3 μg/ml significantly arrested CEMss cells at G0/G1 phase (p<0.05). A constant but increasing pattern-related Sub-G0/G1 index was observed between 12 and 72 h treatment. In relation to this, we further investigated the biochemical events leading to cell death and found that the DCM/F7 fraction increased the cellular levels of caspase-3 and -9 on treated cells. Our results indicated that cytochrome c from mitochondria into the cytosol increased gradually as the DCM/F7 concentration increases, which later lead to the subsequent cleavage of PARP in to 85kDa fragments. On the contrary, Bcl-2 protein was found to decrease concomitantly during treatment.. Collectively, results presented in this study demonstrated that the DCM/F7 fraction inhibited the proliferation of leukemia cells, leading to the programmed cell death, which was confirmed to be through the mitochondrial pathway.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Araceae; Caspase 9; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Dose-Response Relationship, Drug; Electrophoresis, Agar Gel; Flow Cytometry; Humans; Inhibitory Concentration 50; Leukemia; Malaysia; Medicine, Traditional; Mitochondria; Plant Extracts; Poly(ADP-ribose) Polymerases

Lycorine is an alkaloid isolated from the bulb of the Amaryllidaceae Lycoris. Here, we report that treatment with lycorine resulted in survival inhibition and apoptosis induction in human leukemia cell lines. Lycorine induced apoptosis in human leukemia cells via intrinsic mitochondria pathway and caused a rapid-turnover of protein level of Mcl-1 which occurred before caspases activation. Furthermore, pronounced apoptosis accompanied by the down-regulation of Mcl-1 was also observed in blasts from patients with acute myeloid leukemia. Our findings suggest that lycorine may be a good candidate therapeutic agent against leukemia in worth of further evaluation.

Topics: Amaryllidaceae Alkaloids; Apoptosis; Blotting, Western; Caspases; Cytochromes c; Down-Regulation; Humans; Leukemia; Mitochondria; Myeloid Cell Leukemia Sequence 1 Protein; Phenanthridines; Proto-Oncogene Proteins c-bcl-2; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Transcription, Genetic; Tumor Cells, Cultured

To improve our understanding of ionizing radiation effects on immune cells, we investigated steps leading to radiation-induced cell death in MOLT-4, a thymus-derived human leukemia cell. After exposure of MOLT-4 cells to 4 Gy of X-rays, irradiated cells sequentially showed increase in intracellular reactive oxygen species (ROS), decrease in mitochondrial membrane potential, and eventually apoptotic cell death. In the presence of the caspase inhibitor z-VAD-fmk, irradiated cells exhibited necrotic characteristics such as mitochondrial swelling instead of apoptosis. ROS generation was not detected during this necrotic cell death process. These results indicate that radiation-induced apoptosis in MOLT-4 cells requires elevation of intracellular ROS as well as activation of a series of caspases, whereas the cryptic necrosis program--which is independent of intracellular ROS generation and caspase activation--is activated when the apoptosis pathway is blocked.

Topics: Amino Acid Chloromethyl Ketones; Caspase Inhibitors; Caspases; Cell Death; Cell Line, Tumor; Cell Shape; Cytochromes c; Humans; Leukemia; Membrane Potential, Mitochondrial; Mitochondria; Reactive Oxygen Species; X-Rays

Naringenin, a naturally occurring citrus flavonone, has shown cytotoxicity in various human cancer cell lines as well as inhibitory effects on tumor growth and there is increasing interest in its therapeutic applications. In this study, the effect of ectopic Bcl-2 expression on naringenin-induced apoptosis was investigated. We found that Bcl-2 overexpression markedly protected human leukemia U937 cells from time- and dose-dependent induction of apoptosis by naringenin, as did caspase-3 and caspase-9 inhibitors. Additionally, Bcl-2 overexpression attenuated naringenin-induced Bax translocation and cytosolic release of cytochrome c. Our results also indicated that co-administration of HA14-1 and naringenin increased apoptosis in Bcl-2 overexpressing U937 cells by restoring mitochondrial dysfunction and activation of caspase-9 and caspase-3, as well as by cleavage of poly (ADP-ribose) polymerase. Taken together, these observations indicate that Bcl-2 confers apoptosis resistance to naringenin by inhibiting a mitochondrial amplification step in U937 cells.

Topics: Antineoplastic Agents; Antioxidants; Apoptosis; bcl-2-Associated X Protein; Benzopyrans; Caspase Inhibitors; Cell Survival; Cytochromes c; Cytosol; Dose-Response Relationship, Drug; Drug Combinations; Drug Screening Assays, Antitumor; Enzyme Inhibitors; Estrogen Antagonists; Flavanones; Humans; Leukemia; Membrane Potential, Mitochondrial; Mitochondria; Nitriles; Proto-Oncogene Proteins c-bcl-2; U937 Cells

Naturally occurring organic sulfur compounds (OSCs), such as linear allylsulfides from Allium species, are attracting attention in cancer research, since several OSCs were shown to act beneficially both in chemoprevention and in chemotherapy, while hardly exerting any harmful side effects. Hence, we investigated the possible role of different OSCs in the treatment of leukemia. Thereby, we found that the compounds tested in this study induced apoptosis in U937 cells, with an efficiency depending on the number of sulfides, and selected the most promising candidate, diallyltetrasulfide (Al2S4), for detailed mechanistic studies. Here we show that Al2S4 induced an accumulation of cells in early mitosis (G2/M phase), followed by the activation of caspase-dependent apoptosis. The compound counteracted different anti-apoptotic Bcl-2 family members (Bcl-xL, phospho-Bad and Bcl-2), promoted activation of Bax and Bak and induced the release of cytochrome c into the cytoplasm. Treatment by Al2S4 let to the identification of early apoptotic events including Bcl-xL degradation, Bak activation and release of cytochrome c followed by late events including Bcl-2 proteolysis, Bax activation, Bad dephosphorylation, caspase activation, nuclear fragmentation and phosphatidylserine exposure.

Topics: Apoptosis; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; Blood Donors; Caspases; Cell Survival; Cytochromes c; Drug Screening Assays, Antitumor; Enzyme Activation; Flow Cytometry; Health; Humans; Leukemia; Leukocytes, Mononuclear; Mitochondria; Mitosis; Sulfides; Time Factors; U937 Cells

Topics: Carcinoma; Cytochromes c; Humans; Leukemia; Mutation; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational

Both tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and some monoclonal agonistic antibodies against TRAIL receptors have antitumor activity. We have previously prepared a novel monoclonal agonistic antibody against human death receptor 5 (DR5) and designated it as mDRA-6. This study was to explore the Caspase-dependent molecular mechanisms of mDRA-6 inducing apoptosis of human leukemia Jurkat cells.. After exposure to different doses of mDRA-6, DNA fragmentation of Jurkat cells was detected by agarose gel electrophoresis, cell proliferation was detected by MTT assay, and cell apoptosis was detected by flow cytometry after Annexin V-FITC/PI double staining. Jurkat cells were further treated with the inhibitors for Caspase-10, -9, -8 and -3. The active cleavage products of Caspase-10, -9, -8, -3 and poly ADP-ribose polymerase (PARP), BH3 interacting domain death agonist (Bid), truncated Bid (tBid) and cytochrome c (Cyto c), were analyzed by western blot.. After mDRA-6 treatment, DNA fragmentation was detected in Jurkat cells. mDRA-6 inhibited cell proliferation in a dose-dependent manner. When treated with 2.0 microg/mL mDRA-6, the apoptosis rates of Jurkat cells were 16.2% at 0.25 h, 28.3% at 0.5 h, 69.2% at 1 h and 78.2% at 2 h. Interestingly, the mDRA-6-induced apoptosis was repressed by 77.9% by Caspase-8 inhibitor ZIF, 54.2% by Caspase-3 inhibitor ZDF, and 8.7% by Caspase-9 inhibitor ZLF, but was not repressed by Caspase-10 inhibitor ZAF. After mDRA-6 exposure, the proenzymes of Caspase-8, -9 and -3 were reduced and their active cleavage products were increased along with the increase of exposure time, the cleavage products of PARP were also increased, Bid was degraded to tBid, and an abundance of Cyto c was released from mitochondria, but the proenzyme of Caspase-10 showed no change and no cleavage products of Caspase-10 were detectable.. mDRA-6 can induce apoptosis of Jurkat cells via the Caspase-dependent and mitochondrial pathways.

Topics: Antibodies, Monoclonal; Apoptosis; BH3 Interacting Domain Death Agonist Protein; Blotting, Western; Caspase 10; Caspase 3; Caspase 8; Caspase 9; Caspase Inhibitors; Caspases; Cell Proliferation; Cytochromes c; DNA Fragmentation; Dose-Response Relationship, Drug; Electrophoresis, Agar Gel; Flow Cytometry; Humans; Jurkat Cells; Leukemia; Oligopeptides; Poly(ADP-ribose) Polymerases; Receptors, TNF-Related Apoptosis-Inducing Ligand; Time Factors

Compound K [20-O-beta-(D-glucopyranosyl)-20(S)-protopanaxadiol], a metabolite of the protopanaxadiol-type saponins of Panax ginseng C.A. Meyer, has been reported to possess anti-tumor properties to inhibit angiogenesis and to induce tumor apoptosis. In the present study, we investigated the effect of Compound K on apoptosis and explored the underlying mechanisms involved in HL-60 human leukemia cells.. We examined the effect of Compound K on the viabilities of various cancer cell lines using MTT assays. DAPI assay, Annexin V and PI double staining, Western blot assay and immunoprecipitation were used to determine the effect of Compound K on the induction of apoptosis.. Compound K was found to inhibit the viability of HL-60 cells in a dose- and time-dependent manner with an IC50 of 14 muM. Moreover, this cell death had typical features of apoptosis, that is, DNA fragmentation, DNA ladder formation, and the externalization of Annexin V targeted phosphatidylserine residues in HL-60 cells. In addition, compound-K induced a series of intracellular events associated with both the mitochondrial- and death receptor-dependent apoptotic pathways, namely, (1) the activation of caspases-3, -8, and -9; (2) the loss of mitochondrial membrane potential; (3) the release of cytochrome c and Smac/DIABLO to the cytosol; (4) the translocation of Bid and Bax to mitochondria; and (5) the downregulations of Bcl-2 and Bcl-xL. Furthermore, a caspase-8 inhibitor completely abolished caspase-3 activation, Bid cleavage, and subsequent DNA fragmentation by Compound K. Interestingly, the activation of caspase-3 and -8 and DNA fragmentation were significantly prevented in the presence of cycloheximide, suggesting that Compound K-induced apoptosis is dependent on de novo protein synthesis.. The results indicate that caspase-8 plays a key role in Compound K-stimulated apoptosis via the activation of caspase-3 directly or indirectly through Bid cleavage, cytochrome c release, and caspase-9 activation.

Topics: Apoptosis; Apoptosis Regulatory Proteins; Caspase 8; Cytochromes c; Drug Evaluation, Preclinical; Ginsenosides; HeLa Cells; HL-60 Cells; Humans; Intracellular Signaling Peptides and Proteins; Leukemia; Membrane Potentials; Mitochondrial Proteins; Models, Biological; Panax; Saponins; Signal Transduction; Tumor Cells, Cultured; U937 Cells

Despite the significant implication of apoptosis in tumorigenesis, there is no biomarker to assess the extent of ongoing apoptosis in vivo for hematological malignancies. We investigated the potential of serum cytochrome c (cyto-c) as a biomarker for apoptosis. Cyto-c and lactate dehydrogenase (LD) were released into the culture medium from apoptotic cells induced by tumor necrosis factor-related apoptosis-inducing ligand in a time-dependent manner in vitro, with different kinetic patterns. Only one-third of 153 patients with hematological malignancies showed high levels of serum cyto-c (>20 ng/ml). Although serum cyto-c level was roughly correlated to serum LD activity, their different kinetic patterns from serial measurements indicated that serum cyto-c rather than LD is a more sensitive indicator for tracking changes of tumor status. Furthermore, serum cyto-c level stratified patients with acute adult T-cell leukemia into favorable and unfavorable subgroups with 5-year survival rates of 67%vs. 11%. In conclusion, serum cyto-c may provide a fast real-time biomarker for tracking changes of tumor status involved in apoptotic cell death, but lacking disease or cell-type specificity.

Topics: Apoptosis; Biomarkers, Tumor; Cytochromes c; Humans; L-Lactate Dehydrogenase; Leukemia; Lymphoma

Lipoic acid (LA), a potent antioxidant, has been used as a dietary supplement to prevent and treat many diseases, including stroke, diabetes, neurodegenerative and hepatic disorders. Recently, potent anti-tumorigenic effects induced by LA were also reported and evident as assayed by suppression of cell proliferation and induction of apoptosis in malignant cells. However, the mechanism by which LA elicits its chemopreventive effects remains unclear.. Herein, we investigated whether LA elicits its anti-tumor effects by inducing cell cycle arrest and cell death in human promyelocytic HL-60 cells. The results showed that LA inhibits both cell growth and viability in a time- and dose-dependent manner. Disruption of the G1/S and G2/M phases of cell cycle progression accompanied by the induction of apoptosis was also observed following LA treatment. Cell cycle arrest by LA was correlated with dose-dependent down regulation of Rb phosphorylation, likely via suppression of E2F-dependent cell cycle progression with an accompanying inhibition of cyclin E/cdk2 and cyclin B1/cdk1 levels. Evidence supporting the induction of apoptosis by LA was based on the appearance of sub-G1 peak in flow cytometry analysis and the cleavage of poly(ADP-ribose) polymerase (PARP) from its native 112-kDa form to the 89-kDa truncated product in immunoblot assays. Apoptosis elicited by LA was preceded by diminution in the expression of anti-apoptotic protein bcl-2 and increased expression of apoptogenic protein bax, and also the release and translocation of apoptosis inducing factor AIF and cytochrome c from the mitochondria to the nucleus, without altering the subcellular distribution of the caspases.. This study provides evidence that LA induces multiple cell cycle checkpoint arrest and caspase-independent cell death in HL-60 cells, in support of its efficacious potential as a chemopreventive agent.

Topics: Anticarcinogenic Agents; Apoptosis; Apoptosis Inducing Factor; bcl-2-Associated X Protein; Cell Cycle; Cytochromes c; HL-60 Cells; Humans; Leukemia; Poly(ADP-ribose) Polymerases; Protein Transport; Proto-Oncogene Proteins c-bcl-2; Thioctic Acid

Constitutively active tyrosine kinases promote leukemogenesis by increasing cell proliferation and inhibiting apoptosis. However, mechanisms underlying apoptotic inhibition have not been fully elucidated. In many settings, apoptosis occurs by mitochondrial cytochrome c release, which nucleates the Apaf-1/caspase-9 apoptosome. Here we report that the leukemogenic kinases, Bcr-Abl, FLT3/D835Y, and Tel-PDGFRbeta, all can inhibit apoptosome function. In cells expressing these kinases, the previously reported apoptosome inhibitor, Hsp90beta, bound strongly to Apaf-1, preventing cytochrome c-induced Apaf-1 oligomerization and caspase-9 recruitment. Hsp90beta interacted weakly with the apoptosome in untransformed cells. While Hsp90beta was phosphorylated at Ser 226/Ser 255 in untransformed cells, phosphorylation was absent in leukemic cells. Expression of mutant Hsp90beta (S226A/S255A), which mimics the hypophosphorylated form in leukemic cells, conferred resistance to cytochrome c-induced apoptosome activation in normal cells, reflecting enhanced binding of nonphosphorylatable Hsp90beta to Apaf-1. In Bcr-Abl-positive mouse bone marrow cells, nonphosphorylatable Hsp90beta expression conferred imatinib (Gleevec) resistance. These data provide an explanation for apoptosome inhibition by activated leukemogenic tyrosine kinases and suggest that alterations in Hsp90beta-apoptosome interactions may contribute to chemoresistance in leukemias.

Topics: Animals; Apoptosomes; Apoptotic Protease-Activating Factor 1; Benzamides; Bone Marrow Cells; Caspase 9; Cell Line; Cytochromes c; Drug Resistance, Neoplasm; Enzyme Induction; Fusion Proteins, bcr-abl; HSP90 Heat-Shock Proteins; Humans; Imatinib Mesylate; Leukemia; Mice; Mutant Proteins; Phosphorylation; Phosphoserine; Piperazines; Protein Binding; Protein-Tyrosine Kinases; Pyrimidines

Withaferin A, a major chemical constituent of Withania somnifera, has been reported for its tumor cell growth inhibitory activity, antitumor effects, and impairing metastasis and angiogenesis. The mechanism by which withaferin A initiates apoptosis remains poorly understood. In the present report, we investigated the effect of withaferin A on the apoptotic pathway in U937 human promonocytic cells. We show that withaferin A induces apoptosis in association with the activation of caspase-3. JNK and Akt signal pathways play crucial roles in withaferin A-induced apoptosis in U937 cells. Furthermore, we have shown that overexpression of Bcl-2 and active Akt (myr-Akt) in U937 cells inhibited the induction of apoptosis, activation of caspase-3, and PLC-gamma1 cleavage by withaferin A. Taken together, our results indicated that the JNK and Akt pathways and inhibition of NF-kappaB activity were key regulators of apoptosis in response to withaferin A in human leukemia U937 cells.

Topics: Apoptosis; Caspase 3; Caspase Inhibitors; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Down-Regulation; Enzyme Inhibitors; Ergosterol; Humans; JNK Mitogen-Activated Protein Kinases; Leukemia; Matrix Metalloproteinases; NF-kappa B; Phosphorylation; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Withanolides

An extract of artichoke Cynara cardunculus L. (CCE) has been shown to exhibit antioxidant and antigenotoxic properties. In this study, the ability of CCE to inhibit the growth of L1210 and HL-60 leukemia cells was studied. Treatment of leukemia cells with a variety of concentrations of CCE (500-2500 microg/microL) for 24 h resulted in dose-dependent inhibition of leukemia cell growth. The cell growth inhibition was accompanied by G(0)/G(1) cell cycle arrest and by a loss of cells in S phase. Futhermore, apoptosis detected as a sub-G(0) cell population and apoptotic DNA fragmentation was observed. More detailed analyses of apoptosis induced by CCE in HL-60 cells revealed that apoptosis progressed through the caspase-9/-3 pathway, as release of cytochrome c, caspase-9/-3 activations and specific proteolytic cleavage of poly(ADP-ribose) polymerase. Taken together, the results suggest that CCE exerts an antiproliferative activity on leukemia cells and induces apoptosis of these cells through a mitochondrial/caspase dependent pathway.

Topics: Acetates; Animals; Blotting, Western; Caspases; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cynara; Cytochromes c; HL-60 Cells; Humans; Leukemia; Plant Extracts; Solubility

Many anthracene derivatives possess excellent anti-tumour activity and are extensively used clinically as anti-tumour agents. However, their clinical use is frequently limited by emergence of multidrug resistance (MDR) in tumour cells. Therefore, new agents with the ability to overcome MDR are needed for cancer treatment. HL-37, a novel anthracene derivative, exhibited potent anti-cancer activity in both drug-sensitive (K562) and multidrug-resistant (K562/DOX) leukaemia cells. Mechanistically, we found that HL-37 was neither a substrate nor an inhibitor of P-glycoprotein (P-gp) and could overcome apoptotic resistance via up-regulation of p53 protein and down-regulation of Bcl-xL protein. In addition, HL-37 also induced K562/DOX cell apoptosis and a decrease in G(0)/G(1) phase. Moreover, reduction of mitochondrial membrane potential, release of cytochrome c and an increased expression of cleaved protein fragment of caspase-3, caspase-9 and caspase-8 were also observed. Importantly, HL-37 was found to be better tolerated and more effective at inhibiting tumour growth than bisantrene in a xenograft mouse model.

Topics: Animals; Anthracenes; Antineoplastic Agents; Apoptosis; ATP Binding Cassette Transporter, Subfamily B, Member 1; Caspases; Cell Line, Tumor; Cytochromes c; Disease Models, Animal; Doxorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Gene Expression Regulation; Humans; K562 Cells; Leukemia; Male; Membrane Potential, Mitochondrial; Mice; Mice, Inbred ICR

Interferons (IFNs) are pleiotropic cytokines responsible for inducing innate and adaptive immunities against a wide range of viruses and other microbial pathogens. In addition, IFNs also exert antitumor activities due to their antiproliferative, immunomodulatory, proapoptotic functions. In the last decades, the successful clinical application of IFNs for treatment of cancer, particularly leukemia, has improved the quality and longevity of life for many patients. The induction of tumor cell apoptosis by IFNs is believed to contribute, at least in part, to the beneficial effects. IFN subtypes, such as IFN-alpha, IFN-beta, and IFN-gamma, induce apoptosis through cell type-specific signaling pathways, and several putative IFN-stimulated genes (ISGs) with proapoptotic functions have been identified. Here, we analyzed the ability of IFN-alpha, IFN-beta, or IFN-gamma to induce apoptosis in several malignant hematologic cell lines. We found that treatment with IFN-gamma, but not IFN-alpha, or IFN-beta, specifically induces HL-60 leukemia cells to undergo apoptosis. Roughly 30% of HL-60 cells treated for 48 h with IFN-gamma, but not IFN-gamma, or IFN-beta, underwent apoptosis as monitored by annexin V labeling to determine changes in phosphatidylserine (PS) asymmetry and TUNEL assay to detect DNA fragmentation. Consistent with these results, treatment with IFN-gamma, but not IFN-alpha or IFN-beta, induced the release of cytochrome c, activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase (PARP), a well-characterized caspase-3 substrate. Further investigation into the potential mechanism responsible for mitochondrial disruption revealed that treatment with IFN-gamma caused decreased levels of Bcl-2 and increased levels of Bak. This study thus provides the basis for additional research to uncover the molecular mechanism by which IFN-gamma regulates the expression of Bcl-2 family members in various cell types.

Topics: Antineoplastic Agents; Apoptosis; bcl-2 Homologous Antagonist-Killer Protein; Caspase 3; Cell Proliferation; Cytochromes c; HL-60 Cells; Humans; Interferon-alpha; Interferon-beta; Interferon-gamma; K562 Cells; Leukemia; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; U937 Cells

The Bcr-Abl fusion gene encodes for the p210(Bcr-Abl) or p185(Bcr-Abl) tyrosine kinase (TK) implicated in the pathogenesis of chronic myelogenous leukemia (CML) or acute lymphoblastic leukemia, respectively. Because Bcr-Abl TK is chaperoned by Hsp90 (90 kDa heat-shock protein), we investigated the effects of novobiocin (NB), an Hsp90 C-terminal inhibitor, on the viability of the Bcr-Abl-positive human leukemia cells HL-60/Bcr-Abl and K562, the expression of Bcr-Abl protein and the interaction between Hsp90 and Bcr-Abl TK. Present studies demonstrate that NB is a potent inhibitor of the growth of Bcr-Abl-positive human leukemia cells. NB induces cytosolic accumulation of cytochrome c and activation of caspase-9 and caspase-3, triggering apoptosis of HL-60/Bcr-Abl and K562 cells. Treatment of cell lines with NB disrupts Bcr-Abl /Hsp90 and Bcr-Abl /Hsp70 interactions, resulting in a decreased amount of intracellular Bcr-Abl protein levels. Co-treatment with the proteasome inhibitor N-acetyl leucyl-leucyl norlucinal increases NB-mediated accumulation of Bcr-Abl in the detergent-insoluble cellular fraction, which demonstrates that NB promotes proteasomal degradation of Bcr-Abl. Moreover, both imatinib-resistant K562/G01 and primary CML CD34(+) cells are sensitive to NB.

Topics: Apoptosis; Benzamides; Benzoquinones; Blast Crisis; Caspase 3; Caspase 9; Cell Proliferation; Cytochromes c; Extracellular Signal-Regulated MAP Kinases; Fusion Proteins, bcr-abl; HL-60 Cells; HSP90 Heat-Shock Proteins; Humans; Imatinib Mesylate; Immunoprecipitation; K562 Cells; Lactams, Macrocyclic; Leukemia; Novobiocin; Piperazines; Proteasome Endopeptidase Complex; Pyrimidines

Model studies have shown that peptides derived from the N-terminal region of bovine lactoferrin (Lf-B) exhibit antitumor activity against certain cell lines. This activity is due primarily to the peptides' apoptogenic effect. Several reports indicate that cationic residues clustered in two regions of the peptide sequence can be shuffled into one region and thereby increase cytotoxic activity, although the mechanism of this enhanced cytotoxic effect has not been clarified. In this paper, we considered several parameters that determine the mode of cell death after exposure to a native Lf-B derived peptide (Pep1, residues 17-34), and a modified peptide (mPep1) wherein the cationic residues of Pep1 are clustered in a single region of its helical structure. We found that the cytotoxic activity of mPep1 was about 9.6 fold-higher than that of Pep1 against HL-60 cells, as determined by the 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethonyphenol)-2-(4-sulfophenyl)-2 H-tetrazolium (MTS) assay. In investigating the expression of phosphatidylserine, we observed that the native peptide (Pep1) caused both apoptotic cell death and necrotic cell death, depending on the concentration of the peptide. In contrast, the action of mPep1 was exclusively characteristic of necrotic cell death. This observation was further confirmed by agarose gel electrophoresis, in which clear ladder-like DNA bands were observed from cells exposed to Pep1, whereas DNA from cells treated with mPep1 produced a smeared pattern. We extended the study by investigating the release of mitochondrial cytochrome c into the cytosol, and the activation of caspase-3; both peptides caused the release of cytochrome c into the cytosol, and the activation of caspase-3.These results suggest that Pep1 may kill cancer cells by activating an apoptosis-inducing pathway, whereas mPep1 causes necrotic cell death by destroying cellular membrane structure notwithstanding sharing some cellular events with apoptotic cell death.

Topics: Amino Acid Sequence; Apoptosis; Blotting, Western; Caspase 3; Cell Survival; Cytochromes c; Flow Cytometry; HL-60 Cells; Humans; Lactoferrin; Leukemia; Molecular Sequence Data; Necrosis; Peptides

Combined treatment with the medicinal mushroom Ganoderma lucidum and the herb Duchesnea chrysantha extracts (GDE) causes a synergistic induction of mitochondrial damage and apoptosis in HL-60 cells. GDE treatment is selectively toxic to HL-60 leukemia cells whereas no cytotoxic effect is observed in normal peripheral blood mononuclear cells. GDE-induced apoptosis is associated with Bcl-2 down-regulation, Bax translocation, mitochondrial cytochrome c release and caspase-3 activation, suggesting that apoptosis by this combination occurs through the mitochondria-dependent pathway. The present findings suggest that this combination merits further investigation as a potential therapeutic agent for the treatment of cancer.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Basidiomycota; bcl-2-Associated X Protein; Blotting, Western; Caspase 3; Caspase Inhibitors; Cell Survival; Cytochromes c; Dose-Response Relationship, Drug; Enzyme Activation; Flow Cytometry; Growth Inhibitors; HL-60 Cells; Humans; Leukemia; Mitochondria; Mitochondrial Membranes; Plant Extracts; Protein Transport; Rosaceae; Time Factors

Curcumin (diferuloylmethane), a natural cancer chemopreventive compound, has been tested for its action in acute myeloblastic leukemia cell line HL-60. The results clearly show that curcumin induces apoptosis in these cells as evidenced by the release of cytochrome c from mitochondria to the cytosol and increase in the DNA content in sub G1 region as observed in FACS analysis. Apoptosis is apparently mediated by up-regulation of apoptotic gene bax and simultaneous down-regulation of anti-apoptotic gene bcl-2 followed by activation of caspases 3 and 8 and degradation of PARP. Telomerase, a reverse transcriptase, has been found to be activated in more than 80% of human cancers and, therefore, can be considered as a potential marker for tumorigenesis. Certain natural compounds have the potential of inhibiting telomerase activity leading to suppression of cell viability and induction of apoptosis. The present study shows that curcumin-induced apoptosis coincides with the inhibition of telomerase activity in a dose dependent manner.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; Caspase 3; Caspase 8; Curcumin; Cytochromes c; DNA, Neoplasm; Dose-Response Relationship, Drug; Flow Cytometry; HL-60 Cells; Humans; Leukemia; Poly(ADP-ribose) Polymerases; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-bcl-2; Telomerase

Uncaria tomentosa (Wild.) DC., found in the Amazon rain forest in South-America and known commonly as cat's claw, has been used in traditional medicine to prevent and treat inflammation and cancer. Recently, it has been found to possess potent anti-inflammation activities. In this study, we extracted cat's claw using four different solvents of different polarities and compared their relative influence on proliferation in human premyelocytic leukemia HL-60 cell lines. Cat's claw n-hexane extracts (CC-H), ethyl acetate extracts (CC-EA) and n-butanol extracts (CC-B) had a greater anti-cancer effect on HL-60 cells than those extracted with methanol (CC-M). Furthermore, CC-EA induced DNA fragmentation in HL-60 cells in a clearly more a concentration- and time-dependent manner than the other extracts. CC-EA-induced cell death was characterized by cell body shrinkage and chromatin condensation. Further investigating the molecular mechanism behind CC-EA-induced apoptosis, sells treated with CC-EA underwent a rapid loss of mitochondrial transmembrane (DeltaPsi(m)) potential, stimulation of phosphatidylserine flip-flop, release of mitochondrial cytochrome c into cytosol, induction of caspase-3 activity in a time-dependent manner, and induced the cleavage of DNA fragmentation factor (DFF-45) and PARP poly-(ADP-ribose) polymerase (PARP). CC-EA promoted the up-regulation of Fas before the processing and activation of procaspase-8 and cleavage of Bid. In addition, the apoptosis induced by CC-EA was accompanied by up-regulation of Bax, down-regulation of Bcl-X(L) and cleavage of Mcl-1, suggesting that CC-EA may have some compounds that have anti-cancer activities and that further studies using cat's claw extracts need to be pursued. Taken together, the results of our studies show clearly that CC-EA's induction of apoptosis in HL-60 cells may make it very important in the development of medicine that can trigger chemopreventive actions in the body.

Topics: Antineoplastic Agents, Phytogenic; Antioxidants; Apoptosis; Apoptosis Regulatory Proteins; BH3 Interacting Domain Death Agonist Protein; Caspases; Cat's Claw; Cell Membrane; Cyclin-Dependent Kinase Inhibitor Proteins; Cytochromes c; Dose-Response Relationship, Drug; Enzyme Activation; fas Receptor; Genes, bcl-2; HL-60 Cells; Humans; Leukemia; Phosphatidylserines; Plant Extracts; Poly(ADP-ribose) Polymerases; Proteins; Reactive Oxygen Species

Melissoidesin G (MOG) is a new diterpenoid purified from Isodon melissoides, a plant used in Chinese traditional medicine as antitumor and anti-inflammatory agents. In our study, MOG was shown to specifically inhibit the growth of human leukemia cell lines and primary acute myeloid leukemia (AML) blasts via induction of apoptosis, with the evidence of mitochondrial DeltaPsim loss, reactive oxygen species production, caspases activation and nuclear fragmentation. Furthermore, it was shown that thiol-containing antioxidants completely blocked MOG-induced mitochondrial DeltaPsim loss and subsequent cell apoptosis, while the inhibition of apoptosis by benzyloxy-carbonyl-Val-Ala-Asp-fluoromethylketone only partially attenuated mitochondrial DeltaPsim loss, indicating that MOG-induced redox imbalance is an early event upstream to mitochondrial DeltaPsim loss and caspase-3 activation. Consistently, it was found that MOG rapidly decreased the intracellular glutathione (GSH) content in a dose-dependent manner and the significance of GSH depletion in MOG-induced apoptosis was further supported by the protective effects of tert-butylhydroquinone (tBHQ) and the facilitative effects of DL-buthionine (S,R)-sulfoximine (BSO). Furthermore, it was showed that GSH depletion induced by MOG rendered some leukemia cell lines more sensitive to arsenic trioxide (As2O3), doxorubicin or cisplatin. Additionally, the synergistic apoptotic effects of MOG with As2O3 were detected in HL-60 and primary AML cells, but not in normal cells, suggesting the selective toxicity of their combination to the malignant cells. Together, we proposed that MOG alone or administered with other anticancer agents may provide a novel therapeutic strategy for leukemia.

Topics: Antineoplastic Agents; Apoptosis; Arsenic Trioxide; Arsenicals; Caspases; Cytochromes c; Diterpenes; Glutathione; Humans; Isodon; Leukemia; Mitochondria; Molecular Structure; Oxidation-Reduction; Oxides; Phytotherapy; Tumor Cells, Cultured

The objective of this study was to gain insight into the molecular mechanism of induced cell death (apoptosis) by PYRROLO [1,2-b][1,2,5]BENZOTHIADIAZEPINES (PBTDs) series compounds, using human (K562) cells as a model.. We focused our attention on some members of the PBTDs family to test their potential apoptotic activity in K562 cells. Important apoptotic activity was demonstrated, as evidenced by the concentration and percentage of cell death quantified by measuring PI-uptake by flow cytometry, and DNA fragmentation analyzed by agarose gel electrophoresis, generating a characteristic ladder pattern of discontinuous DNA fragments. The expression of Bcl-2 family was tested using western blotting and transfection method.. PBTDs-mediated suppression of K562 cell proliferation was induced by apoptosis characterized by the appearance of DNA fragmentation and was associated with the poly(ADP-ribose)polymerase (PARP) cleavage. PBTD-1 and -3 treatment resulted in caspase-3 activation through down-regulation of Bcl-2 and up-regulation of Bax. Furthermore, we used K562/vector and K562/bcl-2 cells, which were generated by transfection of the cDNA of the Bcl-2 gene. As compared with K562/vector, K562/Bcl-2 cells exhibited a 4-fold greater expression of Bcl-2. Treatment with 10 muM PBTD-1 and -3 for 24 h produced morphological features of apoptosis and DNA fragmentation in K562/vector cells, respectively. In contrast, PBTD-1 and -3-induced caspase-3 activation and apoptosis were inhibited in K562/Bcl-2. Furthermore, Bcl-2 overexpressing cells exhibited less cytocrome c release during PBTDs-induced apoptosis.. These results indicate that PBTDs effectively induce apoptosis of K562 leukemia cells through the activation of caspase cascades. In addition, these findings indicate that Bcl-2 inhibits PBTD-1 and -3 induced-apoptosis via a mechanism that interferes with cytocrome c release, and the activity of caspase-3, which is involved in the execution of apoptosis.

Topics: Apoptosis; bcl-2-Associated X Protein; Benzodiazepines; Caspase 3; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cyclic S-Oxides; Cytochromes c; DNA Fragmentation; Down-Regulation; Genes, bcl-2; Humans; K562 Cells; Leukemia; Mitochondria; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins c-bcl-2

Histone deacetylase (HDAC) inhibitors are promising candidates for molecular-targeted therapy for leukemia. In this study, we investigated the mechanisms of cytotoxic effects of depsipeptide (FK228), one of the most effective HDAC inhibitors against leukemia, using human myeloid leukemic cell lines HL-60 and K562. We found that FK228 activated caspase-9 and a subsequent caspase cascade by perturbing the mitochondrial membrane to release cytochrome c, which was almost completely blocked by overexpression of Bcl-2. The mitochondrial damage was caused by the translocation of Bax but not other pro-apoptotic Bcl-2 family proteins to the mitochondria. FK228 did not affect the interaction between Bax and Bax adaptor proteins such as 14-3-3theta and Ku70. FK228-induced apoptosis and mitochondrial translocation of Bax were markedly enhanced by the proteasome inhibitor bortezomib. The synergistic action of FK228 and bortezomib was at least partly mediated through conformational changes in Bax, which facilitate its translocation to the mitochondria. These results suggest that the combination of HDAC inhibitors and proteasome inhibitors is useful in the treatment of leukemia especially in the context of molecular-targeted therapy. The status of Bcl-2 and Bax may influence the sensitivity of tumors to this combination and thus can be a target of further therapeutic intervention.

Topics: 14-3-3 Proteins; Antibiotics, Antineoplastic; Antigens, Nuclear; Apoptosis; bcl-2-Associated X Protein; Boronic Acids; Bortezomib; Caspase 9; Caspase Inhibitors; Caspases; Cytochromes c; Depsipeptides; DNA-Binding Proteins; Drug Synergism; Enzyme Inhibitors; Histone Deacetylase Inhibitors; Histone Deacetylases; HL-60 Cells; Humans; K562 Cells; Ku Autoantigen; Leukemia; Mitochondria; Mitochondrial Membranes; Protease Inhibitors; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Protein Transport; Pyrazines

Acute lymphoblastic leukemia (ALL), especially T-acute lymphoblastic leukemia (T-ALL), is a common childhood malignant neoplastic disorder. Chemotherapy agents, particularly those that can induce apoptosis, are the major intervening strategy in the treatment of ALL. In this study, we investigated in T-ALL cell line, CCRF-CEM, the in vitro cytotoxic effect and the mechanism of action of baicalin, a compound extracted from Scutellaria baicalensis Georgi and S. rivularis Benth (Labiateae). Results demonstrated that baicalin displayed a remarkable cytotoxic effect in CCRF-CEM, with an IC(50) value of 10.6 microg/ml. It triggered apoptotic effect by fragmentizing cellular DNA and arrested the cell cycle at G(0)/G(1) phase. Baicalin (37.5 microg/ml) had not effected the expression of p53 and Fas protein. It was shown to decline the expression of Bcl-2 (22.0 pg/ml), which consequently caused the loss (52.7%) of transmembrane potential (Delta Psi m) in the mitochondria after 72 hours of treatment. Baicalin (37.5 microg/ml) also elevated the amount of cytosolic cytochrome c (19.2 microg/ml), which finally triggered the activation of caspase-3 (50.1 pmol/min). In conclusion, baicalin was found to induce apoptosis in T-ALL cell lines through multiple pathways. This finding encourages further investigation of baicalin in its role as a potential candidate for chemotherapeutic agents in T-ALL.

Topics: Apoptosis; Caspase 3; Caspases; Cell Cycle; Cell Line, Tumor; Cytochromes c; DNA; Flavonoids; Flow Cytometry; Humans; Leukemia; Membrane Potentials; Proto-Oncogene Proteins c-bcl-2; Tumor Suppressor Protein p53

The aim was to study the apoptotic induction effect of thapsigargin on leukemia cell line K562 and its possible mechanism. After the treatment of leukemia cell line K562 by thapsigargin, morphological change of apoptotic cells was investigated by AO/EB fluorescent staining under fluorescent microscope; apoptosis rate was determined with annexin V-FITC/PI double staining by flow cytometry; intracellular calcium concentrations ([Ca(2+)]i) were measured by fluorescence spectrophotometer with calcium sensitive fluorescence indicator Fura-2/AM; mitochondrial transmembrance potentials (Delta Psi m) was detected on flow cytometry through staining of Rhodamine (Rh123); the changes of caspase-3, -7, -9, -12, cytochrome C, GRP78 proteins were detected by Western blot. The results showed that K562 cells cultured in 4 micromol/L thapsigargin for 48 hours exhibited typical morphological changes of apoptotic cells under fluorescent microscope, including shrinkage of cell, condensation of chromatin, breakage of nuclear, formation of apoptotic bodies, fluorescence of yellow green and pellet observed in early apoptoyic cells and hyacinth fluorescence of chromatin showed in late apoptotic cells. 24 and 48 hours after exposure to 1, 2, 4, 8 micromol/L thapsigargin, the apoptotic rates of K562 were respectively 7.51%, 11.65%, 23.22%, 30.56% and 12.85%, 20.27%, 31.51%, 44.16%, in dose-dependent manner, and were statistically significant when compared with the controls (P < 0.05). The apoptotic rate of K562 was dose- and time-dependent in experiment range. The enhancement of [Ca(2+)]i and the decrease of the Delta Psi m in K562 cells were induced by thapsigargin and were dose-dependent in experiment range, compared with control, P < 0.05. Western blot results indicated that cleavage and activation of caspase-3, -7, -9, -12, releasing of cytochrome C from mitochondria, upregulation of GRP78 expression at the endoplasmic reticulum were induced in K562 cells after 24 hours exposure of 4 micromol/L thapsigargin. It is concluded that thapsigargin induces endoplasmic reticulum stress-induced apoptosis in K562 cells. Endoplasmic reticulum is a novel important initiatory site of apoptosis in cells; the cleavage and activation of caspase-3, -7, -9, -12 play very important role in endoplasmic reticulum stress-induced apoptosis of K562 cells and is one of the important mechanisms for thapsigargin-induced apoptosis. Thapsigargin-induced apoptosis in K562 cells is associated closely with t

Topics: Apoptosis; Calcium-Transporting ATPases; Caspase 3; Caspase 7; Cytochromes c; Endoplasmic Reticulum; Endoplasmic Reticulum Chaperone BiP; Enzyme Inhibitors; Heat-Shock Proteins; Humans; K562 Cells; Leukemia; Mitochondria; Molecular Chaperones; Thapsigargin

In the current study, we examined the effects of the nonpsychoactive cannabinoid, cannabidiol, on the induction of apoptosis in leukemia cells. Exposure of leukemia cells to cannabidiol led to cannabinoid receptor 2 (CB2)-mediated reduction in cell viability and induction in apoptosis. Furthermore, cannabidiol treatment led to a significant decrease in tumor burden and an increase in apoptotic tumors in vivo. From a mechanistic standpoint, cannabidiol exposure resulted in activation of caspase-8, caspase-9, and caspase-3, cleavage of poly(ADP-ribose) polymerase, and a decrease in full-length Bid, suggesting possible cross-talk between the intrinsic and extrinsic apoptotic pathways. The role of the mitochondria was further suggested as exposure to cannabidiol led to loss of mitochondrial membrane potential and release of cytochrome c. It is noteworthy that cannabidiol exposure led to an increase in reactive oxygen species (ROS) production as well as an increase in the expression of the NAD(P)H oxidases Nox4 and p22(phox). Furthermore, cannabidiol-induced apoptosis and reactive oxygen species (ROS) levels could be blocked by treatment with the ROS scavengers or the NAD(P)H oxidase inhibitors. Finally, cannabidiol exposure led to a decrease in the levels of p-p38 mitogen-activated protein kinase, which could be blocked by treatment with a CB2-selective antagonist or ROS scavenger. Together, the results from this study reveal that cannabidiol, acting through CB2 and regulation of Nox4 and p22(phox) expression, may be a novel and highly selective treatment for leukemia.

Topics: Animals; Apoptosis; Cannabidiol; Caspases; Cell Survival; Cytochromes c; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Female; Humans; JNK Mitogen-Activated Protein Kinases; Jurkat Cells; Leukemia; Membrane Potentials; Mice; Mitochondrial Membranes; NADPH Oxidase 4; NADPH Oxidases; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Reactive Oxygen Species; Receptor, Cannabinoid, CB2

Coriolus versicolor (CV), also called Yunzhi, has been demonstrated to exert anti-tumor effects on various types of cancer cells. Our previous studies have demonstrated that a standardized aqueous ethanol extract prepared from CV inhibited the proliferation of human leukemia cells via induction of apoptosis. The present study aimed to evaluate the underlying mechanisms of apoptosis through modulation of Bax, Bcl-2 and cytochrome c protein expressions in a human pro-myelocytic leukemia (HL-60) cell line, as well as the potential of the CV extract as anti-leukemia agent using the athymic mouse xenograft model. Our results demonstrated that the CV extract dose-dependently suppressed the proliferation of HL-60 cells (IC50 = 150.6 microg/ml), with increased nucleosome production from apoptotic cells. Expression of pro-apoptotic protein Bax was significantly up-regulated in HL-60 cells treated with the CV extract, especially after 16 and 24 h. Meanwhile, expression of anti-apoptotic protein Bcl-2 was concomitantly down-regulated, as reflected by the increased Bax/Bcl-2 ratio. The CV extract markedly, but transiently, promoted the release of cytochrome c from mitochondria to cytosol after 24-h incubation. In vivo studies in the athymic nude mouse xenograft model also confirmed the growth-inhibitory activity of the CV extract on human leukemia cells. In conclusion, the CV extract attenuated the human leukemia cell proliferation in vivo, and in vitro possibly by inducing apoptosis through the mitochondrial pathway. The CV extract is likely to be valuable for the treatment of some forms of human leukemia.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Cell Proliferation; Cytochromes c; Cytosol; Drugs, Chinese Herbal; HL-60 Cells; Humans; Leukemia; Mice; Mice, Inbred BALB C; Mice, Nude; Mitochondria; Plant Extracts; Polyporales; Proto-Oncogene Proteins c-bcl-2; Transplantation, Heterologous

Using K562 and HL60 cell lines, we have investigated the anti-tumoral activity of d-limonene, a monocyclic monoterpene, in human leukemia cells. Apoptosis was evaluated by Hoechst staining and by the annexin V/propidium iodide binding assay. d-Limonene induced apoptosis in a dose- and time-dependent manner in both cell lines. Our findings and data, demonstrating an increase in Bax protein expression, the release of cytochrome c from mitochondria, and an increase in caspase-9 and cleaved caspase-3, but not caspase-8, after the treatment of d-limonene, all suggest that the mitochondrial death pathway is primarily involved in the development of d-limonene-induced apoptosis.

Topics: Anticarcinogenic Agents; Apoptosis; Caspases; Cell Differentiation; Cell Line, Tumor; Cell Survival; Cyclohexenes; Cytochromes c; DNA Fragmentation; HL-60 Cells; Humans; K562 Cells; Leukemia; Limonene; Mitochondria; Terpenes

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces programmed cell death through the caspase activation cascade and translocation of cleaved Bid (tBid) by the apical caspase-8 to mitochondria to induce oligomerization of multidomain Bax and Bak. However, the roles of prosurvival Bcl-2 family proteins in TRAIL apoptosis remain elusive. Here we showed that, besides the specific cleavage and activation of Bid by caspase-8 and caspase-3, TRAIL-induced apoptosis in Jurkat T cells required the specific cleavage of Mcl-1 at Asp-127 and Asp-157 by caspase-3, while other prototypic antiapoptotic factors such as Bcl-2 or Bcl-X(L) seemed not to be affected. Mutation at Asp-127 and Asp-157 of Mcl-1 led to cellular resistance to TRAIL-induced apoptosis. In sharp contrast to cycloheximide-induced Mcl-1 dilapidation, TRAIL did not activate proteasomal degradation of Mcl-1 in Jurkat cells. We further established for the first time that the C-terminal domain of Mcl-1 became proapoptotic as a result of caspase-3 cleavage, and its physical interaction and cooperation with tBid, Bak, and voltage-dependent anion-selective channel 1 promoted mitochondrial apoptosis. These results suggested that removal of N-terminal domains of Bid by caspase-8 and Mcl-1 by caspase-3 enabled the maximal mitochondrial perturbation that potentiated TRAIL-induced apoptosis.

Topics: Amino Acid Sequence; Animals; Apoptosis; Apoptosis Regulatory Proteins; Aspartic Acid; bcl-X Protein; BH3 Interacting Domain Death Agonist Protein; Binding Sites; Carrier Proteins; Caspase 3; Caspase 8; Caspases; Cell Death; Cell Line, Tumor; Cell Survival; Cycloheximide; Cytochromes c; Down-Regulation; Glutathione Transferase; HeLa Cells; Humans; Immunoprecipitation; Jurkat Cells; Leukemia; Membrane Glycoproteins; Microscopy, Fluorescence; Mitochondria; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasm Proteins; Plasmids; Point Mutation; Proteasome Endopeptidase Complex; Protein Structure, Tertiary; Protein Synthesis Inhibitors; Proto-Oncogene Proteins c-bcl-2; Rats; Reticulocytes; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; RNA, Small Interfering; TNF-Related Apoptosis-Inducing Ligand; Tumor Necrosis Factor-alpha

Interactions between the protein kinase C and Chk1 inhibitor UCN-01 and rapamycin in human leukemia cells have been investigated in relation to apoptosis induction. Treatment of U937 monocytic leukemia cells with rapamycin (10 nmol/L) in conjunction with a minimally toxic concentration of UCN-01 (100 nmol/L) for 36 hours resulted in marked potentiation of mitochondrial injury (i.e., loss of mitochondrial membrane potential and cytosolic release of cytochrome c, AIF, and Smac/DIABLO), caspase activation, and apoptosis. The release of cytochrome c, AIF, and Smac/DIABLO were inhibited by BOC-D-fmk, indicating that their release was caspase dependent. These events were associated with marked down-regulation of Raf-1, MEK, and ERK phosphorylation, diminished Akt activation, and enhanced phosphorylation of c-Jun NH2-terminal kinase (JNK). Coadministration of UCN-01 and rapamycin reduced the expression levels of the antiapoptotic members of the Bcl-2 family Mcl-1 and Bcl-xL and diminished the expression of cyclin D1 and p34(cdc2). Furthermore, enforced expression of a constitutively active MEK1 or, to a lesser extent, myristoylated Akt construct partially but significantly attenuated UCN-01/rapamycin-mediated lethality in both U937 and Jurkat cell systems. Finally, inhibition of the stress-related JNK by SP600125 or by the expression of a dominant-negative mutant of c-Jun significantly attenuated apoptosis induced by rapamycin/UCN-01. Together, these findings indicate that the mammalian target of rapamycin inhibitor potentiates UCN-01 cytotoxicity in a variety of human leukemia cell types and suggest that inhibition of both Raf-1/MEK/ERK and Akt cytoprotective signaling pathways as well as JNK activation contribute to this phenomenon.

Topics: Antibiotics, Antineoplastic; Antineoplastic Agents; Apoptosis; Caspases; CDC2 Protein Kinase; Cell Line, Tumor; Cyclin D1; Cytochromes c; Dose-Response Relationship, Drug; Down-Regulation; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Genes, Dominant; Humans; Immunoblotting; JNK Mitogen-Activated Protein Kinases; Jurkat Cells; Leukemia; MAP Kinase Kinase 1; MAP Kinase Kinase 4; Mitogen-Activated Protein Kinase Kinases; Phosphorylation; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-raf; Signal Transduction; Sirolimus; Staurosporine; Time Factors; U937 Cells

The release of holocytochrome c (cyt c) from mitochondria into the cytosol is reportedly a landmark of the execution phase of apoptosis. As shown here, the P-glycoprotein- (P-gp) expressing K562/ADR cell line (but not the parental K562 cell line) exhibits both cytosolic and mitochondrial cyt c in the absence of any signs of apoptosis. K562/ADR cells were found to be relatively resistant to a variety of different inducers of apoptosis, and blocking the P-gp did not reverse this resistance. The release of cyt c in non-apoptotic K562/ADR cells was not accompanied by that of any other mitochondrial apoptogenic protein, such as AIF or Smac/DIABLO, and was inhibited by Bcl-2 over expression. In addition, using a cell-free system, we show that mitochondria isolated from K562/ADR cells spontaneously released cyt c. These data suggest that cyt c release may be compatible with the preservation of mitochondrial integrity and function, as well as cell proliferation.

Topics: Apoptosis; Apoptosis Regulatory Proteins; ATP Binding Cassette Transporter, Subfamily B, Member 1; Blotting, Western; Cell Line; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Cytosol; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Electrophoresis, Polyacrylamide Gel; Enzyme Activation; Enzyme-Linked Immunosorbent Assay; Gene Expression Regulation, Neoplastic; Humans; Intracellular Signaling Peptides and Proteins; K562 Cells; Leukemia; Microscopy, Confocal; Microscopy, Electron; Mitochondria; Mitochondrial Proteins; Polymerase Chain Reaction; Proto-Oncogene Proteins c-bcl-2; Time Factors; Transfection

Sapphyrins are pentapyrrolic, metal-free, expanded porphyrins. In the present study, the activity of sapphyrins as anticancer agents in hematopoietic-derived tumor cells was explored. It was found that a dihydroxylated water-soluble sapphyrin derivative (PCI-2000) is a potent inducer of apoptosis in a wide variety of tumor cell lines including lymphoma (Ramos, DHL-4, and HF-1), leukemia (Jurkat and HL-60), and myeloma (8226/S, 1-310, C2E3, and 1-414). PCI-2000 triggers an apoptotic pathway in these tumor cells as shown by release of cytochrome c from mitochondria; activation of caspases 9, 8, and 3; cleavage of the caspase substrate poly(ADP-ribose) polymerase; and Annexin V binding. Apoptosis can be partially inhibited by overexpression of the antiapoptotic protein Bcl-2 or treatment with benzyloxycarbonyl-valine-alanine-aspartic acid-fluoromethylketone, a cell-permeable caspase inhibitor. Both PCI-2000 and PCI-2010, a tetrahydroxy bis-carbamate derivative of PCI-2000, result in increased levels of phosphorylated p38 mitogen-activated protein kinase. Inhibition of p38 mitogen-activated protein kinase phosphorylation resulted in a synergistic increase of PCI-2000 cytotoxicity. PCI-2010 showed less toxicity in mice than PCI-2000 and was active in slowing the growth of Ramos and HL-60 tumor xenografts in nude mice. These results provide preclinical rationale for the further study of sapphyrins for potential use in the treatment of hematopoietic-derived tumors.

Topics: Angiogenesis Inhibitors; Animals; Apoptosis; Caspases; Cell Line, Tumor; Cytochromes c; Cytoplasm; Enzyme Activation; Gene Expression Regulation, Neoplastic; Humans; Leukemia; Lymphoma; Mice; Mice, Nude; Mitochondria; Molecular Structure; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Porphyrins; Proto-Oncogene Proteins c-bcl-2; Xenograft Model Antitumor Assays

Interactions between the novel histone deacetylase inhibitor LAQ824 and the cyclin-dependent kinase inhibitor roscovitine were examined in human leukemia cells. Pretreatment (24 hours) with a subtoxic concentration of LAQ824 (30 nmol/L) followed by a minimally toxic concentration of roscovitine (10 micromol/L; 24 hours) resulted in greater than additive effects on apoptosis in U937, Jurkat, and HL-60 human leukemia cells and blasts from three patients with acute myelogenous leukemia. These events were associated with enhanced conformational changes in Bax; mitochondrial release of cytochrome c, Smac/DIABLO, and apoptosis-inducing factor; and a marked increase in caspase activation. LAQ824/roscovitine-treated cells displayed caspase-dependent down-regulation of p21(CIP1) and Mcl-1 and a pronounced caspase-independent reduction in X-linked inhibitor of apoptosis (XIAP) expression. The lethality of this regimen was significantly attenuated by ectopic expression of XIAP, a nuclear localization signal-defective p21(CIP1) mutant, Mcl-1, and Bcl-2. Combined exposure to LAQ824 and roscovitine resulted in a significant reduction in XIAP mRNA levels and diminished phosphorylation of the carboxyl-terminal domain of RNA polymerase II. Notably, roscovitine blocked LAQ824-mediated differentiation. Finally, LAQ824 and roscovitine individually and in combination triggered an increase in generation of reactive oxygen species; moreover, coadministration of the free radical scavenger N-acetylcysteine prevented LAQ824/roscovitine-mediated mitochondrial injury and apoptosis. Collectively, these findings suggest that combined treatment of human leukemia cells with LAQ824 and roscovitine disrupts maturation and synergistically induces apoptosis, lending further support for an antileukemic strategy combining novel histone deacetylase and cyclin-dependent kinase inhibitors.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Inducing Factor; Blotting, Western; Cell Cycle; Cell Line, Tumor; Cyclin-Dependent Kinase Inhibitor p21; Cytochromes c; Cytosol; Down-Regulation; Enzyme Inhibitors; Flow Cytometry; Histone Deacetylase Inhibitors; HL-60 Cells; Humans; Hydroxamic Acids; Jurkat Cells; Leukemia; Membrane Potentials; Mitochondria; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasm Proteins; Protein Conformation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-bcl-2; Purines; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; Roscovitine; Time Factors; U937 Cells; X-Linked Inhibitor of Apoptosis Protein

Effects of the tyrphostin tyrosine kinase inhibitor adaphostin (NSC 680410) have been examined in human leukemia cells (Jurkat, U937) in relation to mitochondrial events, apoptosis, and perturbations in signaling and cell cycle regulatory events. Exposure of cells to adaphostin concentrations > or =0.75 microM for intervals > or =6 h resulted in a pronounced release of cytochrome c and AIF, activation of caspase-9, -8, and -3, and apoptosis. These events were accompanied by the caspase-independent downregulation of Raf-1, inactivation of MEK1/2, ERK, Akt, p70S6K, dephosphorylation of GSK-3, and activation of c-Jun-N-terminal kinase (JNK) and p38 MAPK. Adaphostin also induced cleavage and dephosphorylation of pRb on CDK2- and CDK4-specific sites, as well as the caspase-dependent downregulation of cyclin D1. Inducible expression of a constitutively active MEK1 construct markedly diminished adaphostin-induced cytochrome c and AIF release, JNK activation, and apoptosis in Jurkat cells. Ectopic expression of Raf-1 or constitutively activated (myristolated) Akt also significantly attenuated adaphostin-induced apoptosis, but protection was less than that conferred by enforced activation of MEK. Lastly, antioxidants (e.g., L-N-acetylcysteine; L-NAC) opposed adaphostin-mediated mitochondrial dysfunction, Raf-1/MEK/ERK downregulation, JNK activation, and apoptosis. However, in contrast to L-NAC, enforced activation of MEK failed to block adaphostin-mediated ROS generation. Together, these findings demonstrate that the tyrphostin adaphostin induces multiple perturbations in signal transduction pathways in human leukemia cells, particularly inactivation of the cytoprotective Raf-1/MEK/ERK and Akt cascades, that culminate in mitochondrial injury, caspase activation, and apoptosis. They also suggest that adaphostin-related oxidative stress acts upstream of perturbations in these signaling pathways to trigger the cell death process.

Topics: Adamantane; Apoptosis; Apoptosis Inducing Factor; Cytochromes c; Flavoproteins; Humans; Hydroquinones; Jurkat Cells; Leukemia; MAP Kinase Kinase Kinases; Membrane Proteins; Mitogen-Activated Protein Kinases; Protein Serine-Threonine Kinases; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-raf

The purpose of the present study was to investigate the effects of phenothiazines (at clinically relevant doses) on the viability and proliferation of leukemic cell lines and normal lymphocytes, and to investigate the possibility of specific induction of apoptosis in leukemic cells.. Phenothiazines with different chemical structure and hydrophobicity were used: chlorpromazine (CPZ); levomepromazine (LVPZ); prometazine (PMZ); trifluoperazine (TFPZ); thioridazine (TRDZ). The leukemic cell lines used were: Daudi and Raji (derived from Burkitt's lymphoma), K-562 (derived from myelogenous leukemia), and BALL-1, MOLT-4, HPB-ALL and CCRF-HSB-2 (derived from acute lymphoblastic leukemia). The cytotoxicity of the phenothiazines was determined by a CellTiter-Glo luminescent cell viability assay, using ATP bioluminescence as a marker of cell viability as well as a marker of mitochondrial activity. The proliferation of leukemic cells was determined using a CellTiter-AQ cell proliferation assay which is based on the reduction of a methyl-tetrazolium compound to the formazan product. Apoptosis induction was estimated using phosphatidylserine (PSer) translocation to the cell surface and DNA fragmentation as characteristics of the process.. Phenothiazines (at concentrations in the range 0.1-10 micro M) did not affect the viability of normal lymphocytes during a 24-h incubation. Moreover, about 15-20% increase in ATP bioluminescence was observed in normal cells during treatment with 40 micro M phenothiazines. In contrast, the phenothiazines manifested strong cytotoxicity and antiproliferative activity against leukemic cells. The most powerful drugs were TFPZ and TRDZ, followed by CPZ. They showed a significant cytotoxic effect against leukemic cells even at 5-10 micro M. The most sensitive cell lines were MOLT-4 and Raji, and the most resistant were HPB-ALL and CCRF-HSB-2. All phenothiazines induced PSer exposure on the surface of leukemic cells, but not of normal lymphocytes. TFPZ, TRDZ and CPZ also induced DNA fragmentation in almost all leukemic cell lines during a 48-h incubation. The strongest apoptotic agent was TRDZ. The apoptosis induction was not accompanied by a significant release of cytochrome c from the mitochondria into the cytoplasm of native cells. Moreover, the drugs markedly suppressed Ca(2+)-induced cytochrome c release in isolated mitochondria of leukemic cells.. The results suggest that in clinically relevant doses (up to 20 micro M) some phenothiazines (TFPZ, TRDZ, CPZ) expressed a selective cytotoxicity and antiproliferative activity, and induced apoptosis in leukemic cells without any influence on the viability of normal lymphocytes. It is considered that the mechanism of apoptosis induction in phenothiazine-treated leukemic cells is associated with inhibition of mitochondrial DNA polymerase and decreased ATP production, which are crucial events for the viability of cancer cells.

Topics: Adenosine Triphosphate; Antineoplastic Agents; Apoptosis; Cell Division; Cell Line, Tumor; Cell Survival; Cytochromes c; Dose-Response Relationship, Drug; Humans; Leukemia; Luminescent Measurements; Lymphocytes; Phenothiazines

Mahanine, a carbazole alkaloid occurs in the edible part of Micromelum minutum, Murraya koenigii and related species has been found to induce apoptosis in human myeloid cancer cell (HL-60). Concentration of 10 microM mahanine caused a complete inhibition of cell proliferation and the induction of apoptosis in a time dependent manner. Mahanine-induced cell death was characterized with the changes in nuclear morphology, DNA fragmentation, activation of caspase like activities, poly(ADP-ribose) polymerase cleavage, release of cytochrome c into cytosol and stimulation of reactive oxygen species generation. The cell death was completely prevented by a pancaspase inhibitor benzyloxycarbonyl-L-aspart-1-yl-[(2,6-dichlorobenzoyl)oxy]methane (Z-Asp-CH(2)-DCB). Mahanine activated various caspases such as caspase-3, -6, -8 and -9 (like) activities but not caspase-1 like activity. More than 70% cell survival was observed in the presence of a caspase-3 inhibitor. In addition, co-treatment of cyclosporin A markedly increased the survival of mahanine-treated HL-60 cells. Flow cytometric analysis revealed that mahanine decreased the mitochondrial membrane potential of intact cells, and disrupted cell cycle progression by increasing the number of cells in sub-diploid region, concomitantly with the decrease of cells in diploid phases, particularly at late hours of apoptosis. The overall results suggest that mahanine down regulates cell survival factors by activation of caspase-3 through mitochondrial dependent pathway, and disrupts cell cycle progression.

Topics: Antineoplastic Agents; Apoptosis; Aspartic Acid; Carbazoles; Caspase 3; Caspase Inhibitors; Caspases; Cell Cycle; Cell Division; Cysteine Proteinase Inhibitors; Cytochromes c; Cytosol; DNA; DNA Fragmentation; HL-60 Cells; Humans; Leukemia; Mitochondria; Oligopeptides; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Protease Inhibitors; Proteins; Reactive Oxygen Species

The role of p53 in apoptosis and the contrasting p53 status in tumors prompted us to investigate the bleomycin-induced apoptosis in p53-null human leukemia HL-60 cells (bleomycin at 160 microM for 7.5 h). Cells with apoptotic phenotype increased from 0.87% in controls to 9.40% in bleomycin-treated cells. Both the enzymes, caspase-3 and -8, were activated. Furthermore, the apoptotic phenotypes totally disappeared with zVAD-fmk, a caspase inhibitor. Besides, cytochrome c release from mitochondria happened simultaneously to apoptotic phenotypes, shrinkage of mitochondria but being independent of the mitochondrial permeability transition, since cyclosporine A and bongkrekic acid were inefficient on induced apoptosis. On the other hand, incubations with bleomycin (BLM) did not result in detectable changes in the expression of Bcl-2- and Bax-mRNA neither Bcl-2- or Bax-proteins. In conclusion, we suggest that BLM can produce apoptosis independently of p53 through three mechanisms: i) at the nuclear level by its endonuclease activities; ii) at the cell membrane, by activating caspases; and iii) at the mitochondria by releasing cytochrome c. These results indicate that BLM-induced apoptosis in HL-60 cells results from the activation of a mitochondria-dependent caspase cascade which includes also the activation of the initiator caspase-8.

Topics: Amino Acid Chloromethyl Ketones; Antimetabolites, Antineoplastic; Apoptosis; bcl-2-Associated X Protein; Bleomycin; Blotting, Western; Bongkrekic Acid; Caspase 3; Caspase 8; Caspases; Cell Line; Cyclosporine; Cytochromes c; DNA Fragmentation; Enzyme Activation; Genes, p53; HL-60 Cells; Humans; Leukemia; Microscopy, Electron; Mitochondria; Phenotype; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA, Messenger; Time Factors; Tumor Suppressor Protein p53

The hierarchy of events accompanying induction of apoptosis by the proteasome inhibitor Bortezomib was investigated in Jurkat lymphoblastic and U937 myelomonocytic leukemia cells. Treatment of Jurkat or U937 cells with Bortezomib resulted in activation of c-Jun-N-terminal kinase (JNK) and p38 MAPK (mitogen-activated protein kinase), inactivation of extracellular signal-regulating kinase 1/2 (ERK1/2), cytochrome c release, caspase-9, -3, and -8 activation, and apoptosis. Bortezomib-mediated cytochrome c release and caspase activation were blocked by the pharmacologic JNK inhibitor SP600125, but lethality was not diminished by the p38 MAPK inhibitor SB203580. Inducible expression of a constitutively active MEK1 construct blocked Bortezomib-mediated ERK1/2 inactivation, significantly attenuated Bortezomib lethality, and unexpectedly prevented JNK activation. Conversely, pharmacologic MEK/ERK1/2 inhibition promoted Bortezomib-mediated JNK activation and apoptosis. Lastly, the antioxidant N-acetyl-l-cysteine (LNAC) attenuated Bortezomib-mediated reactive oxygen species (ROS) generation, ERK inactivation, JNK activation, mitochondrial dysfunction, and apoptosis. In contrast, enforced MEK1 and ERK1/2 activation or JNK inhibition did not modify Bortezomib-induced ROS production. Together, these findings suggest that in human leukemia cells, Bortezomib-induced oxidative injury operates at a proximal point in the cell death cascade to antagonize cytoprotective ERK1/2 signaling, promote activation of the stress-related JNK pathway, and to trigger mitochondrial dysfunction, caspase activation, and apoptosis. They also suggest the presence of a feedback loop wherein Bortezomib-mediated ERK1/2 inactivation contributes to JNK activation, thereby amplifying the cell death process.

Topics: Anthracenes; Antineoplastic Agents; Apoptosis; Boronic Acids; Bortezomib; Caspases; Cytochromes c; Enzyme Activation; Enzyme Inhibitors; Humans; Imidazoles; JNK Mitogen-Activated Protein Kinases; Jurkat Cells; Leukemia; MAP Kinase Signaling System; Membrane Potentials; Mitochondria; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Models, Biological; Protease Inhibitors; Pyrazines; Pyridines; Reactive Oxygen Species; Signal Transduction; U937 Cells

VR-3848, a novel peptide derived from Euphobiaceae, is shown herein to induce apoptosis at nanomolar concentrations in the leukemic Jurkat cell line. Apoptosis was associated with activation of caspases, release of cytochrome c from mitochondria, fragmentation of nuclear DNA, and externalization of phosphatidylserine on the cell surface. Overexpression of mitochondria-targeted Bcl-2 abrogated VR-3848-induced killing in this model. Primary human interleukin (IL)-2-activated T lymphocytes were considerably less sensitive to VR-3848-induced apoptosis as compared to Jurkat cells. VR-3848 thus holds the promise of being a potent and selective anti-cancer agent that deserves further exploration.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Caspases; Cytochromes c; Enzyme Activation; Euphorbiaceae; Humans; Jurkat Cells; Leukemia; Mitochondria

Deficient activation of apoptosis signaling pathways may be responsible for treatment failure of malignant diseases. In primary leukemia samples the detection of deficient mitochondrial apoptosis signaling would enable identification of chemo-resistant cells. To investigate the key events of apoptosis at the mitochondrial level, we developed a flow cytometric method for simultaneous detection of mitochondrial cytochrome c release and caspase-3 processing using conformation sensitive monoclonal antibodies. This method proved to identify deficient mitochondrial apoptosis signaling in leukemia cells overexpressing Bcl-2 by a pattern of apoptosis resistance, deficient cytochrome c reduction and partial processing of caspase-3. In primary leukemia cells, reduction of cytochrome c and caspase-3 activation was induced by treatment with anticancer drugs in vitro. In leukemia cells of a patient with resistant disease, a pattern of deficient apoptosis signaling as in Bcl-2 transfected cells was observed, suggesting that deficient mitochondrial signaling contributed to the clinical phenotype of drug resistance in this patient. Flow cytometric analysis of mitochondrial apoptosis signaling may provide a useful tool for the prediction of drug resistance and treatment failure in primary leukemia.

Topics: Antibodies, Monoclonal; Apoptosis; Blotting, Western; Caspase 3; Caspases; Cell Membrane Permeability; Cyclophosphamide; Cytochromes c; Drug Resistance, Neoplasm; Etoposide; fas Receptor; Flow Cytometry; Humans; Jurkat Cells; Leukemia; Leukemia, Lymphoid; Leukemia, Myeloid; Microscopy, Fluorescence; Mitochondria; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; Transfection

Betulinic acid (BA), a natural component isolated from Birch trees, effectively induces apoptosis in neuroectodermal and epithelial tumor cells and exerts little toxicity in animal trials. Here, we show that BA-induced marked apoptosis in 65% of primary pediatric acute leukemia cells and all leukemia cell lines tested. When compared for in vitro efficiency with conventionally used cytotoxic drugs, BA was more potent than nine out of 10 standard therapeutics and especially efficient in tumor relapse. No crossresistances were found between BA and any cytotoxic drug. Intracellular apoptosis signaling in leukemia tumor cells paralleled the pathway found in neuroectodermal cells involving caspases, but not death receptors. In isolated mitochondria, BA induced release of both cytochrome c and Smac. Taken together, BA potently induces apoptosis in leukemia cells and should be further evaluated as a future drug to treat leukemia.

Topics: Adolescent; Antineoplastic Agents, Phytogenic; Apoptosis; Apoptosis Regulatory Proteins; Betulinic Acid; Carrier Proteins; Caspases; Child; Child, Preschool; Cytochromes c; Drug Interactions; Female; Humans; Infant; Intracellular Signaling Peptides and Proteins; Leukemia; Male; Mitochondrial Proteins; Pentacyclic Triterpenes; Secondary Prevention; Signal Transduction; Triterpenes; Tumor Cells, Cultured

Chemotherapeutic drugs that inhibit the synthesis of DNA precursor thymidine triphosphate cause apoptosis, although the mechanism underlying this process remains rather unknown. Here, we describe thymineless death of human myeloid leukemia U937 cells treated with the thymidylate-synthase inhibitor 5'-fluoro- 2'-deoxyuridine (FUdR). This apoptotic process was shown to be independent of p53, reactive oxygen species generation and CD95 activation. Caspases were activated downstream of cytochrome c but upstream of mitochondrial depolarization. Furthermore, FUdR-induced apoptosis required the presence of glucose in the culture medium at a step upstream of the release of cytochrome c from mitochondria.

Topics: Antimetabolites, Antineoplastic; Apoptosis; Caspases; Cell Line, Tumor; Cell Survival; Cytochromes c; Enzyme Inhibitors; fas Receptor; Floxuridine; Genes, p53; Glucose; Glutathione; HL-60 Cells; Humans; Leukemia; Mitochondria; Reactive Oxygen Species; Thymidine; Thymidylate Synthase; U937 Cells; Uridine

Interactions between the cyclin-dependent kinase inhibitor flavopiridol (FP) and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL/Apo2L), were examined in human leukemia cells (U937 and Jurkat). Coexposure of cells to marginally toxic concentrations of TRAIL and FP (24 h) synergistically increased mitochondrial injury (eg, cytochrome c, AIF, Smac/DIABLO release), cytoplasmic depletion of Bax, activation of Bid as well as caspase-8 and -3, PARP cleavage, and apoptosis. Coadministration of TRAIL markedly increased FP-induced apoptosis in leukemic cells ectopically expressing Bcl-2, Bcl-x(L), or a phosphorylation loop-deleted form of Bcl-2 (DeltaBcl-2), whereas lethality was substantially attenuated in cells ectopically expressing CrmA, dominant-negative-FADD, or dominant-negative-caspase-8. TRAIL/FP induced no discernible changes in FLIP, DR4, DR5, Mcl-1, or survivin expression, modest declines in levels of DcR2 and c-IAP, but resulted in the marked transcriptional downregulation of XIAP. Moreover, cells stably expressing an XIAP-antisense construct exhibited a pronounced increase in TRAIL sensitivity comparable to degrees of apoptosis achieved with TRAIL/FP. Conversely, enforced XIAP expression significantly attenuated caspase activation and TRAIL/FP lethality. Together, these findings suggest that simultaneous activation of the intrinsic and extrinsic apoptotic pathways by TRAIL and FP synergistically induces apoptosis in human leukemia cells through a mechanism that involves FP-mediated XIAP downregulation.

Topics: Apoptosis; Apoptosis Inducing Factor; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; bcl-X Protein; BH3 Interacting Domain Death Agonist Protein; Carrier Proteins; Caspases; Cell Cycle; Complement Membrane Attack Complex; Complement System Proteins; Cytochromes c; Down-Regulation; Drug Interactions; Drug Synergism; Flavonoids; Flavoproteins; Glycoproteins; HL-60 Cells; Humans; Intracellular Signaling Peptides and Proteins; Jurkat Cells; Leukemia; Membrane Glycoproteins; Membrane Proteins; Mitochondria; Mitochondrial Proteins; Multiple Myeloma; Phosphorylation; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Proteins; Proto-Oncogene Proteins c-bcl-2; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; TNF-Related Apoptosis-Inducing Ligand; Transcription, Genetic; Tumor Necrosis Factor-alpha; U937 Cells; X-Linked Inhibitor of Apoptosis Protein

The in vitro effects of resveratrol (RES) on apoptotic pathway in human chronic myeloid (K562) and acute lymphoblastic (HSB-2) leukemia cells were investigated. RES treatment of both cell types significantly and irreversibly inhibited their growth, associated with extensive apoptosis and increase in hypodiploid cells. Cell cycle analysis showed accumulation in G(1) phase in HSB-2 drug exposed cells, while only K562-treated cells exhibited a marked accumulation in S phase with a concomitant decrease in G(1) and G(2)/M at 24 h. Moreover, RES caused internucleosomal DNA fragmentation, even if K562 cells were found less sensitive to the drug, as compared to HSB-2 cells, which also reacted earlier to the treatment. RES-induced apoptosis was associated with an increase of Bax expression and a marked release of cytochrome c from mitochondria. Interestingly, K562 cells exhibited a basal content of glutathione 10-fold that of HSB-2 cells, which increased after 24-48 h RES exposure, together with increment of glutathione reductase and peroxidase activities. However, the major resistance to apoptosis of K562 cells cannot be attributed to their higher pool of reducing power, since neither the inhibition of glutathione synthesis by buthionine sulphoximine nor glutathione depletion by diethylmaleate, sensitized these cells. In addition, glutathione enrichment of HSB-2 cells by N-acetylcysteine did not prevent the apoptotic effects of RES. Our data indicate that RES commitment to apoptosis in both cell lines is independent from the intracellular content of glutathione, while it is associated with either the enhanced expression of Bax and cytochrome c release.

Topics: Antioxidants; Apoptosis; bcl-2-Associated X Protein; Caspases; Cell Proliferation; Cell Survival; Cytochromes c; Enzyme Activation; Glutathione; Humans; K562 Cells; Leukemia; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Resveratrol; Stilbenes; Tumor Cells, Cultured

Aplidine is a promising antitumor agent derived from the Mediterranean tunicate Aplidium albicans. We have found that Aplidine at nM concentrations (10-100 nM) induced apoptosis in human leukemic cell lines and primary leukemic cell cultures from leukemic patients. Inhibition of the Fas (CD95)/Fas ligand (CD95L) signaling pathway with an antagonistic anti-Fas antibody partially inhibited Aplidine-induced apoptosis. L929 cells were resistant to Aplidine action but underwent apoptosis after transfection with human Fas cDNA. Aplidine induced a rapid and sustained c-Jun NH(2)-terminal kinase activation, and pretreatment with curcumin or SP600125 inhibited Aplidine-induced c-Jun NH(2)-terminal kinase activation and apoptosis. However, inhibition of extracellular signal-regulated kinase and p38 kinase signaling pathways did not affect Aplidine-induced apoptosis. Aplidine induced caspase-3 activation, and caspase inhibition prevented Aplidine-induced apoptosis. Aplidine failed to induce apoptosis in MCF-7 breast cancer cells, defective in caspase-3, additionally implicating caspase-3 in its proapoptotic action. Aplidine also triggered an early release of cytochrome c from mitochondria, and overexpression of bcl-2 by gene transfer abrogated mitochondrial cytochrome c release and apoptosis. Aplidine rapidly induced cleavage of Bid, a mediator that connects the Fas/CD95 cell death receptor to the mitochondrial apoptosis pathway. Primary cultures of normal human cells, including hepatocytes and resting peripheral blood lymphocytes, were spared or weakly affected after Aplidine treatment. Nevertheless, mitogen (phytohemagglutinin/interleukin-2)-activated T lymphocytes resulted sensitively to the apoptotic action of Aplidine. Thus, Aplidine is an extremely potent and rapid apoptotic inducer on leukemic cells that triggers Fas/CD95- and mitochondrial-mediated apoptotic signaling routes, and shows a rather selective apoptotic action on cancer cells and activated T cells.

Topics: Anthracenes; Apoptosis; BH3 Interacting Domain Death Agonist Protein; Blotting, Western; Carrier Proteins; Caspase 3; Caspases; Cell Line, Tumor; Cells, Cultured; Curcumin; Cytochromes c; Depsipeptides; DNA, Complementary; Dose-Response Relationship, Drug; Enzyme Activation; fas Receptor; Flow Cytometry; Glutathione Transferase; Hepatocytes; HL-60 Cells; Humans; JNK Mitogen-Activated Protein Kinases; Jurkat Cells; Leukemia; MAP Kinase Kinase 4; Microscopy, Fluorescence; Mitochondria; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Peptides, Cyclic; Protein Transport; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; Time Factors; Tumor Cells, Cultured

In the present study, we investigated the effect of tetraarsenic oxide (As4O6, 2,4,6,8,9,10-Hexaoxa-1,3,5,7-tetraarsatricyclo[3.3.1.13,7]decane) upon induction of apoptosis in arsenic trioxide (diarsenic oxide, As2O3) resistant U937 leukemic cells. As4O6 induced apoptosis in U937 leukemic cells at much lower concentrations than As2O3 via an early increase of cellular reactive oxygen species (ROS), and a decrease in cellular mitochondrial membrane potential, followed by cytochrome c release and caspase-3 activation. As4O6 generated ROS and induced caspase-3 activation more potently than As2O3 in U937 cells. Incubation of the cells with N-acetyl-L-cysteine and catalase resulted in significant suppression of As4O6-induced apoptotic cell death. These results show that the generation of ROS leads to the consequences associated with apoptosis induced by As4O6. In conclusion, As4O6 might be a new arsenic compound which may induce apoptosis in U937 leukemic cells by activating unique apoptotic signaling mediated by ROS more potently than As2O3, and deserves further evaluation.

Topics: Apoptosis; Arsenic; Arsenic Trioxide; Arsenicals; Caspase 3; Caspases; Catalase; Cytochromes c; Dose-Response Relationship, Drug; Enzyme Activation; Humans; Hydrogen Peroxide; Leukemia; Membrane Potentials; Mitochondria; Oxides; Reactive Oxygen Species; Time Factors; U937 Cells

The BH3-only protein, PUMA, plays an important role in p53-mediated apoptosis. The apoptotic effect of PUMA on the mitochondria was studied using a p53-negative, human leukemia K562 cell line. Overexpression of PUMA was accompanied by an increased Bax expression, Bax conformational change, and translocation to mitochondria. A PUMA-BH3 peptide can induce Bax conformational change, cytochrome c release, and reduction in the mitochondrial membrane potential (DeltaPsi(m)) in isolated K562 mitochondria and can be inhibited by Bcl-XL. The homo-dimer of Bax/Bax was also weakly shown after mitochondria were treated with PUMA-BH3 peptide but may not be lethal for PUMA-induced apoptosis in K562 cells. Our results suggest that PUMA-induced Bax conformational change and Bax translocation to mitochondria can be separate events and the conformational change in Bax is crucial for PUMA-induced mitochondrial dysfunction.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; Blotting, Western; Cell Line, Tumor; Cross-Linking Reagents; Cytochromes c; Cytosol; Dimerization; Flow Cytometry; Humans; K562 Cells; Leukemia; Membrane Potentials; Mice; Mitochondria; Peptides; Protein Conformation; Protein Transport; Proteins; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Subcellular Fractions; Transfection; Tumor Suppressor Protein p53

Apicidin, a histone deacetylase inhibitor, is a novel cyclic tetrapeptide that exhibits potent antiproliferative activity against various cancer cell lines. The aim of this study was to examine the potential of apicidin to induce apoptosis in human Bcr-Abl-positive leukemia cells and to assess the mechanism of apicidin-induced apoptosis.. Cells were exposed to various concentrations of apicidin for 2-72 h, after which the levels of apoptosis, histone acetylation, mitochondrial damage, caspase activation, and Bcr-Abl expression were assessed.. Apicidin induced apoptosis in K562 cells in a concentration- and time-dependent manner. Similarly, apicidin notably induced the apoptosis in the primary leukemic blasts obtained from chronic myelogenous leukemia patients in blast crisis. The acetylated histone H4 levels increased in a concentration-dependent manner in the K562 cells. However, the timing of cell death caused by apicidin did not exactly correlate with the histone deacetylase inhibitory effect. The disruption of the mitochondrial membrane potential, cytochrome c release into the cytosol, and the mitochondrial Bax translocation were notably demonstrated after the apicidin treatment. Apicidin induced the proteolytic cleavage of procaspase-9, -3, -8, and poly(ADP-ribose) polymerase. Pretreatment of the K562 cells with the caspase-3 inhibitor, DEVD-CHO, completely inhibited the apicidin-induced apoptosis, suggesting that apicidin-induced apoptosis was caspase-dependent. The Fas/Fas ligand death receptor pathway was not involved in the apicidin-mediated apoptosis in K562 cells. Pretreatment of the cells with the caspase-9 inhibitor LEHD-fmk abrogated the apicidin- induced cleavage of procaspase-3, -8, and poly(ADP-ribose) polymerase. The p210 Bcr-Abl protein levels were notably decreased after the apicidin treatment, with near complete loss after 48 h. Reverse transcription-PCR assay demonstrated that the Bcr-Abl mRNA level was also remarkably decreased in a time-dependent manner.. These results indicate that apicidin effectively induces the apoptosis of Bcr-Abl-positive leukemia cells through the activation of the mitochondrial pathway-dependent caspase cascades. The down-regulation of Bcr-Abl mRNA might also be one of the mechanisms implicated in the apicidin-mediated apoptosis in the K562 cells. This study provides the rationale to additionally investigate apicidin as a potential therapeutic agent for the drug-resistant Bcr-Abl-positive leukemia cells.

Topics: Annexin A5; Apoptosis; bcl-2-Associated X Protein; Biological Transport; Blotting, Western; Caspase 3; Caspase 8; Caspase 9; Caspases; Cell Cycle; Cell Line, Tumor; Coloring Agents; Cytochromes c; Cytosol; DNA Fragmentation; Down-Regulation; Enzyme Activation; Enzyme Inhibitors; Fusion Proteins, bcr-abl; Genes, abl; Histone Deacetylase Inhibitors; Histones; Humans; K562 Cells; Leukemia; Mitochondria; Oligopeptides; Peptides, Cyclic; Poly(ADP-ribose) Polymerases; Protein Transport; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Reverse Transcriptase Polymerase Chain Reaction; Time Factors

As diverse pruritic cutaneous diseases respond to ultraviolet treatment, we have examined whether ultraviolet light is capable of inducing apoptosis in mast cells. Human mast cell line 1 (HMC1) derived from a patient with malignant mastocytosis and purified skin mast cells were irradiated with single doses of ultraviolet B or ultraviolet A1, or pretreated with 8-methoxypsoralen prior to ultraviolet A1 exposure. After 0 to 48 h of incubation, the percentage of apoptotic and dead cells was assessed. In HMC1 cells, morphologic features of apoptosis were further evaluated by electron microscopy. All ultraviolet treatment induced apoptosis of HMC1 cells in a time- and dose-dependent manner. Apoptosis was associated with activation of caspase-3, release of cytochrome C, cleavage of poly(ADP-ribose)-polymerase, and nuclear accumulation of p53. In contrast, resting skin mast cells were resistant to ultraviolet light induced apoptosis. After incubation with stem cell factor and interleukin-4 for 2 wk, however, slowly proliferating skin mast cells also underwent apoptosis in response to ultraviolet light. In conclusion, these data demonstrate that ultraviolet light directly affects mast cells, but mainly aims at the proliferating mast cells as found in mastocytosis and mast cell dependent pruritic diseases, where increased numbers are observed due to the recruitment mast cell precursors from the blood.

Topics: Apoptosis; Caspase 3; Caspases; Cell Differentiation; Cell Division; Cell Line, Tumor; Cytochromes c; Humans; Leukemia; Mast Cells; Mastocytosis; Poly(ADP-ribose) Polymerases; Skin; Tumor Suppressor Protein p53; Ultraviolet Rays

We first report the mechanism for the inhibitory effect of the lysine analog, thialysine on human acute leukemia Jurkat T cells. When Jurkat T cells were treated with thialysine (0.32-2.5 mM), apoptotic cell death along with several biochemical events such as mitochondrial cytochrome c release, caspase-9 activation, caspase-3 activation, degradation of poly (ADP-ribose) polymerase, and DNA fragmentation was induced in a dose- and time-dependent manner. However, these thialysine-induced apoptotic events were significantly abrogated by an ectopic expression of Bcl-xL, which is known to block mitochondrial cytochrome c release. Decylubiquinone, a mitochondrial permeability transition pore inhibitor, also suppressed thialysine-induced apoptotic events. Comparison of the thialysine-induced alterations in the cell cycle distribution between Jurkat T cells transfected with Bcl-xL gene (J/Bcl-xL) and Jurkat T cells transfected with vector (J/Neo) revealed that the apoptotic cells were mainly derived from the cells accumulated in S and G2/M phases following thialysine treatment. The interruption of cell cycle progression in the presence of thialysine was accompanied by a significant decline in the protein level of cdk4, cdk6, cdc2, cyclin A, cyclin B1, and cyclin E. These results demonstrate that the cytotoxic activity of thialysine toward Jurkat T cells is attributable to not only apoptotic cell death mediated by a mitochondria-dependent death signaling pathway, but also interruption of cell cycle progression by a massive down-regulation in the level of cdks and cyclins.

Topics: Apoptosis; bcl-X Protein; Caspases; Cell Cycle; Cell Survival; Cysteine; Cytochromes c; Enzyme Activation; Humans; Jurkat Cells; Leukemia; Lysine; Mitochondria; Protein Synthesis Inhibitors; Proto-Oncogene Proteins c-bcl-2; Tumor Cells, Cultured

Interactions between histone deacetylase (HDAC) inhibitors and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), also known as Apo2 ligand, were examined in human leukemia cells (e.g., U937, Jurkat, and HL-60). Simultaneous exposure of cells to 100-ng/ml TRAIL with either 1-mM sodium butyrate or 2- micro M suberoylanilide hydroxamic acid resulted in a striking increase in leukemic cell mitochondrial damage, caspase activation, and apoptosis. Lethal effects were significantly diminished in U937 cells ectopically expressing dominant-negative caspase-8, dominant-negative Fas-associated death domain, CrmA (receptor pathway), or Bcl-2 or Bcl-X(L) (mitochondrial pathway). Analysis of mitochondrial events in U937 cells exposed to TRAIL/HDAC inhibitors revealed enhanced Bid activation and Bax translocation, loss of mitochondrial membrane potential, and cytoplasmic release of cytochrome c, Smac/DIABLO, and apoptosis-inducing factor. No changes were observed in expression of FLICE-like inhibitory protein, TRAIL receptors, or reactive oxygen species generation. TRAIL/HDAC inhibitor-induced apoptosis triggered caspase-dependent cleavage of p21(WAF1/CIP1); moreover, enforced expression of a nuclear localization signal deletant form of p21(WAF1/CIP1) significantly diminished lethality. Lastly, p27(KIP1), pRb, X-linked inhibitor of apoptosis, and Bcl-2 displayed extensive proteolysis. These findings indicate that coadministration of TRAIL with HDAC inhibitors synergistically induces apoptosis in human myeloid leukemia cells and provide further evidence that simultaneous activation of the extrinsic and intrinsic pathways in such cells leads to a dramatic increase in mitochondrial injury and activation of the caspase cascade.

Topics: Apoptosis; Apoptosis Regulatory Proteins; Caspase 3; Caspase 8; Caspases; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Cytochromes c; Enzyme Activation; Enzyme Inhibitors; G1 Phase; Histone Deacetylase Inhibitors; Humans; Leukemia; Membrane Glycoproteins; Mitochondria; Phosphorylation; Reactive Oxygen Species; Retinoblastoma Protein; TNF-Related Apoptosis-Inducing Ligand; Tumor Necrosis Factor-alpha

Investigation of the role of mitochondrial membrane potential (MMP) in the homoharringtonine (HHT)-induced apoptosis.. Annexin V staining, flow cytometry and confocal laser scan microscopy were used to observe the relationship between Bax, cytochrome C and MMP in the HHT-induced apoptosis of leukemic T lymphocytic line Molt-3.. The induction of apoptosis by HHT resulted in the translocation of Bax from cytosol to mitochondrial membrane and the decrease of cellular MMP, followed by the release of cytochrome C from mitochondria to cytosol.. Changes of mitochondrial membrane potential might play a critical role in the HHT-induced apoptosis of leukemic T-cells.

Topics: Apoptosis; bcl-2-Associated X Protein; Cell Line, Tumor; Cytochromes c; Cytosol; Harringtonines; Homoharringtonine; Humans; Leukemia; Membrane Potential, Mitochondrial; Mitochondrial Membranes; Protein Transport; T-Lymphocytes

Topics: Animals; Cytochromes c; Disease; Ectromelia; Extremities; Leukemia; Mice; Rabbits; Syndrome; Vaccination; Virus Diseases