cytochrome-c-t and Precursor-Cell-Lymphoblastic-Leukemia-Lymphoma

L-Asparaginase-II from Escherichia coli (EcA) is a central component in the treatment of acute lymphoblastic leukemia (ALL). However, the therapeutic efficacy of EcA is limited due to immunogenicity and a short half-life in the patient. Here, we performed rational mutagenesis to obtain EcA variants with a potential to improve ALL treatment. Several variants, especially W66Y and Y176F, killed the ALL cells more efficiently than did wild-type EcA (WT-EcA), although nonleukemic peripheral blood monocytes were not affected. Several assays, including Western blotting, annexin-V/propidium iodide binding, comet, and micronuclei assays, showed that the reduction in viability of leukemic cells is due to the increase in caspase-3, cytochrome c release, poly(ADP-ribose) polymerase activation, down-regulation of anti-apoptotic protein Bcl-XL, an arrest of the cell cycle at the G0/G1 phase, and eventually apoptosis. Both W66Y and Y176F induced significantly more apoptosis in lymphocytes derived from ALL patients. In addition, Y176F and Y176S exhibited greatly decreased glutaminase activity, whereas K288S/Y176F, a variant mutated in one of the immunodominant epitopes, showed reduced antigenicity. Further in vivo immunogenicity studies in mice showed that K288S/Y176F was 10-fold less immunogenic as compared with WT-EcA. Moreover, sera obtained from WT-EcA immunized mice and ALL patients who were given asparaginase therapy for several weeks recognized the K288S/Y176F mutant significantly less than the WT-EcA. Further mechanistic studies revealed that W66Y, Y176F, and K288S/Y176F rapidly depleted asparagine and also down-regulated the transcription of asparagine synthetase as compared with WT-EcA. These highly desirable attributes of these variants could significantly advance asparaginase therapy of leukemia in the future.

Topics: Amino Acid Substitution; Animals; Antineoplastic Agents; Asparaginase; bcl-X Protein; Caspase 3; Cell Line, Tumor; Cytochromes c; Epitopes, B-Lymphocyte; Escherichia coli Proteins; Female; Humans; Male; Mice; Mice, Inbred BALB C; Mutagenesis; Mutation, Missense; Precursor Cell Lymphoblastic Leukemia-Lymphoma

In the present study, we searched selective cytotoxicity and mitochondria mediated apoptosis of novel COX-2 inhibitor 2-(4-(Methylsulfonyl)phenyl)imidazo[1,2-

Topics: Antineoplastic Agents; Apoptosis; B-Lymphocytes; Caspase 3; Cell Survival; Child; Child, Preschool; Cyclooxygenase 2 Inhibitors; Cytochromes c; Female; Humans; Male; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Membranes; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Reactive Oxygen Species; Succinate Dehydrogenase

Estrogens, as the main female steroid hormones have multiple proven effects on reproductive and non- reproductive systems. Expression of ERα and ERβ, two dominant estrogen receptors, in peripheral blood mononuclear cells in certain B-cell malignancies and the existence of estrogens receptors on mitochondria is open to question that estrogen likely has an impact on the cancerous lymphocytes life span. Acute Lymphoblastic Leukemia (ALL) is the frequent pediatric malignity which is recurrent and hardly curable in many cases. The malignant cells are generally resistant to apoptosis caused the severe lymphocytes accumulation in the peripheral blood.. By focusing on mitochondria as a life/death center of the cell; in the current research we compared cytotoxicity effects of a new ferrocenyl derivative with raloxifene as well-known SERMs considering the apoptotic process and survival of cancerous lymphocytes.. We demonstrated that both ferrocenyl derivative and raloxifene could cause mitochondrial lesion and initiate the apoptosis process by caspase activation and cytochrome c release.. In brief, the ferrocenyl derivative could induce estrogen-related selective apoptosis on cancerous lymphocytes by affecting mitochondrial receptors.

Topics: Antineoplastic Agents; Apoptosis; Child; Child, Preschool; Cytochromes c; Female; Ferrous Compounds; Humans; Lymphocytes; Male; Membrane Potential, Mitochondrial; Mitochondria; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Receptors, Estrogen

Background: Acute lymphoblastic leukemia (ALL) is one of the most dominant malignancies among children,\ characterized by production of immature and dysfunctional blasts which are resistant to cytotoxic chemotherapeutic\ agents. Therefore, research protocols are currently focusing on discovery of novel anti-cancer agents to enhance survival\ rates and decrease unwanted side effects. Approximately two-thirds of the planet is covered by oceans with a massive\ range of marine organisms of interest to scientists in pharmaceutical fields. Methods: Among marine resources, sponges\ are known to have beneficial effects in the treatment of numerous malignancies. One fraction of crude extracts containing\ α-Santonin was made from the Persian Gulf marine sponge, Dysidea avara, and investigated for anticancer effects.\ Results: Treatment of ALL B-lymphocytes with the Dysidea avara extract caused augmentation in ROS generation,\ decline in mitochondrial membrane potential, mitochondrial swelling, release of cytochrome c from mitochondria\ and activation of caspase-3 only in mitochondria isolated from B-ALL lymphocytes. Conclusion: In brief, our results\ suggest that Dysidea avara extracts may selectively induce apoptosis in malignant pediatric lymphocytes.

Topics: Animals; Antineoplastic Agents; Apoptosis; B-Lymphocytes; Cell Proliferation; Child; Cytochromes c; Dysidea; Humans; Indian Ocean; Membrane Potential, Mitochondrial; Mitochondria; Porifera; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Santonin; Tumor Cells, Cultured

β lactam-structured Cox-2 inhibitors, possesses anti-proliferative and anti-inflammatory effects.. In this research, the actions of a synthetic β lactam-structured Cox-2 inhibitor with 4-(4- (Methylsulfonyl) phenyl)-1-pentyl-3-phenoxyazetidin-2-one on cellular viability of cancerous lymphoblast obtained from patients with acute lymphocytic leukemia (ALL) and normal lymphocytes obtained from healthy donors were compared.. % the cell viability of cancerouslymphoblasts and normal lymphocytes treated with β lactam derivatives were assayed with MTT test. Early apoptosis and necrosis were detected by double staining of annexin V/ propidium iodide and activity of caspase 3 as the final mediator in apoptotic mode of cell death was evaluated by colorimetric assay.. Our results showed that β lactam derivatives inhibited the proliferation of cancerous lymphoblast but not normal lymphocytes in a concentration-dependent mode by inducing apoptosis. Treatment with β lactam derivatives resulted in a rapid loss of mitochondrial trans-membrane potential and induction of reactive oxygen species (ROS) formation, and cytochrome c release in cytosol of mitochondria resulted in activation of procaspase-9 and formation of active apoptosome.. These findings suggest that 4-(4-(Methylsulfonyl)phenyl)-1-pentyl-3-phenoxyazetidin-2-one as a β lactam could induce ROS-mediated death signaling throughmitochondrial pathway that results in apoptosis in only cancerous lymphoblast cells. The stimulationof apoptosis by β lactams may provide a pivotal mechanismfor their anticancer effect in acute lymphocytic leukemia cells.

Topics: Antineoplastic Agents; Azetines; B-Lymphocytes; beta-Lactams; Cell Proliferation; Child; Child, Preschool; Cytochromes c; Cytosol; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Female; Humans; Male; Mitochondria; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Reactive Oxygen Species; Structure-Activity Relationship

Leukemia is one of the deadliest types of cancer. Lack of effective treatment strategies has resulted in an extensive quest for new therapeutic molecules against it. This study explores the molecular mechanism of anticancer activity of P16, a semisynthetic analog of parthenin, against the human acute lymphoblastic leukemia MOLT-4 cells. P16 displayed antiproliferative activity in different cancer cell lines; however, MOLT-4 cells showed highest sensitivity for P16 with IC50 value of 0.6μM. Further studies revealed that P16 induced cell death by apoptosis. It caused mitochondrial stress, which was mediated by the translocation of Bax from cytosol to mitochondria and release of cytochrome c into the cytosol and consequent activation of caspase-9. However, P16 was also able to activate caspase-8, thus involving both extrinsic and intrinsic pathways of apoptosis. Further, activation of caspase-3 led to cleavage of its target proteins PARP-1 and ICAD, which resulted in apoptotic DNA damage. P16 induced apoptosis was accompanied by the down-regulation of important leukemic cell survival proteins like pAKT (S473), pAKT (T308), pP70S6K, pCRAF, and pERK1/2. However, inhibition of caspases by Z-VAD-FMK reversed the down-regulatory effect of P16 on pAKT (S473) and pP70S6K, as evident by the cell viability assay and flow cytometric analysis but this inhibition did not completely reverse the antiproliferative effect of P16, thereby indicating the role of additional factors apart from caspases in P16 induced apoptosis in MOLT-4 cells. Owing to its antiproliferative potential against leukemia cells, P16 can further be explored as an effective therapeutics against leukemia.

Topics: Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Caspases; Cell Line, Tumor; Cell Proliferation; Cytochromes c; DNA Damage; Down-Regulation; Heterocyclic Compounds, 4 or More Rings; Humans; MAP Kinase Signaling System; Membrane Potential, Mitochondrial; Phosphatidylinositol 3-Kinases; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-akt; Sesquiterpenes

Bortezomib is a highly selective inhibitor of the 26S proteasome and has been approved for clinical use in the treatment of relapsing and refractory multiple myeloma and mantle cell lymphoma. Clinical trials are also underway to assess the role of bortezomib in several other human malignancies, including leukemia. However, the mechanism(s) by which bortezomib acts remain to be fully understood. Here, we studied the molecular requirements of bortezomib-induced apoptosis using the human T-cell leukemic Jurkat cells stably transfected with or without shRNA against apoptotic protease-activating factor-1 (Apaf-1). The Apaf-1-deficient Jurkat T cells were resistant to bortezomib-induced apoptosis, as assessed by caspase-3 activity, poly(ADP-ribose) polymerase cleavage, phosphatidylserine externalization, and hypodiploid DNA content. In contrast, Apaf-1-deficient cells were sensitive to Fas-induced apoptosis. Bortezomib induced an upregulation of the pro-apoptotic protein Noxa, loss of mitochondrial transmembrane potential, and release of cytochrome c in cells expressing or not expressing Apaf-1. Transient silencing of Apaf-1 expression in RPMI 8402 T-cell leukemic cells also diminished bortezomib-induced apoptosis. Fas-associated death domain (FADD)-deficient Jurkat cells were resistant to Fas-mediated apoptosis yet remained sensitive to bortezomib. Our results show that bortezomib induces apoptosis by regulating pathways that are mechanistically different from those activated upon death receptor ligation. Furthermore, in silico analyses of public transcriptomics databases indicated elevated Apaf-1 expression in several hematologic malignancies, including acute lymphoblastic and myeloid leukemia. We also noted variable Apaf-1 expression in a panel of samples from patients with acute lymphoblastic leukemia. Our results suggest that the expression of Apaf-1 may be predictive of the response to proteasome inhibition.

Topics: Adolescent; Antineoplastic Agents; Apoptosis; Apoptotic Protease-Activating Factor 1; Boronic Acids; Bortezomib; Caspase 3; Child; Child, Preschool; Cytochromes c; fas Receptor; Fas-Associated Death Domain Protein; Gene Silencing; Humans; Jurkat Cells; Leukemia, Myeloid; Membrane Potential, Mitochondrial; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2; Pyrazines; RNA, Small Interfering; Transcriptome

Heparin induces apoptosis on peripheral neutrophils, mononuclear cells of the healthy controls, and on lymphoblasts of the patients with acute lymphoblastic leukemia, in vitro. We studied the caspase-9 activity and cytochrome C level as the indicators of the apoptotic effect of heparin on lymphoblasts by the intrinsic pathway of apoptosis. Twenty samples of the patients with acute lymphoblastic leukemia were included in the study. Cytochrome C level and caspase-9 activity were concomitantly determined with the percentage of apoptotic lymphoblasts when incubated in 0, 10, and 20 U/mL heparin concentrations at 0, 1, and 2 hours. The percentages of apoptosis of lymphoblasts at the first hour were higher than those at 0 and 2 hours in 10 and 20 U/mL heparin concentrations, separately (P<0.05). The mean percentage of apoptosis of lymphoblasts in 20 U/mL heparin levels was significantly higher than those in 0 and 10 U/mL heparin levels at 1 and 2 hours (P<0.05). The highest apoptotic effect of heparin on lymphoblasts was determined at the first hour in 20 U/mL heparin concentration. The mean caspase-9 activitity at the first hour was significantly higher than the values at 0 and 2 hours in 10 and 20 U/mL heparin levels, separately (P<0.05). The mean caspase-9 activity in 20 U/mL heparin concentration was significantly higher than values in 0 and 10 U/mL heparin concentrations at 1 and 2 hours (P<0.05). The highest caspase-9 activity was determined in 20 U/mL heparin levels at the first hour. The mean cytochrome C level at the first hour was significantly higher than those at 0 and 2 hours in 10 and 20 U/mL heparin concentrations, separately (P<0.05). The highest cytochrome C level was determined in 20 U/mL heparin concentration at the first hour. We claimed that heparin induces the apoptosis of lymphoblasts by the activation of the intrinsic pathway.

Topics: Apoptosis; Caspase 9; Cytochromes c; DNA; Dose-Response Relationship, Drug; Enzyme Activation; Flow Cytometry; Heparin; Humans; Lymphocytes; Precursor Cell Lymphoblastic Leukemia-Lymphoma

Aqueous Viscum album L. extracts are widely used for anti-cancer therapies. Due to their low solubility, triterpenes (which are known to act on cancers), do not occur in aqueous extracts in significant amounts. Using cyclodextrins, we have found it possible to solubilize mistletoe triterpene acids and to determine their effects on acute lymphoblastic leukaemia (ALL) in vitro and in vivo.. A C.B-17/SCID model of pre-B ALL (NALM-6) was used to test efficacy and mechanisms of treatment with lectin- and triterpene acid containing preparations in vivo. Cytotoxicity of increasing concentrations of V. album L. preparations was assessed in vitro. Apoptosis was determined using mitochondrial membrane potential measurements, annexin V/PI, western blot analyses and caspase inhibitor assays.. Solubilized triterpene acid- or lectin-containing V. album L. extracts inhibited cell proliferation and demonstrated cytotoxic properties in vitro. Annexin V/PI and mitochondrial membrane potential assays indicated that dose-dependent induction of apoptosis was the main mechanism. Combination (viscumTT) of lectin- (viscum) and triterpene-containing (TT) extracts resulted in greatest induction of apoptosis. Furthermore, caspase activity demonstrated that these extracts were able to induce apoptosis through both caspase-8 and -9 dependent pathways. In vivo experimentation showed that treatment of mice with viscumTT combination prolonged mean survival to 50.5 days compared to 39.3 days in the phosphate-buffered saline group.. Here for the first time, we have demonstrated that either solubilized triterpene acids or lectins and combinations thereof, induce dose-dependent apoptosis in the ALL cell line NALM-6 via caspase-8 and -9 dependent pathways.

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 3; Caspase 8; Caspase 9; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Drug Synergism; Female; Humans; Membrane Potential, Mitochondrial; Mice; Mice, SCID; Oleanolic Acid; Phytotherapy; Plant Extracts; Plant Lectins; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Solubility; Triterpenes; Viscum album; Xenograft Model Antitumor Assays

Terpinen-4-ol is a terpene found in the rhizome of Plai (Zingiber montanum (Koenig) Link ex Dietr.). In this study apoptogenic activity and mechanisms of cell death induced by terpinen-4-ol were investigated in the human leukemic MOLT-4 cell line. Terpinen-4-ol exhibited cytotoxicity in MOLT-4 cells, with characteristic morphological features of apoptosis by Wright's staining. The mode of cell death was confirmed to be apoptosis by flow cytometric analysis after staining with annexin V-FITC and propidium iodide. A sub-G1 peak in DNA histograms of cell cycle assays was observed. Terpinen-4-ol induced-MOLT-4 cell apoptosis mediated through an intrinsic pathway involving the loss of mitochondrial transmembrane potential (MTP) and release of cytochrome c into the cytosol. In addition, terpinen-4-ol also induced apoptosis via an extrinsic pathway by caspase-8 activation resulting in the cleavage of cytosolic Bid. Truncated-Bid (tBid) translocated to mitochondria and activated the mitochondrial pathway in conjunction with down-regulation of Bcl-2 protein expression. Caspase-3 activity also increased. In conclusion, terpinen-4-ol can induce human leukemic MOLT-4 cell apoptosis via both intrinsic and extrinsic pathways.

Topics: Annexin A5; Apoptosis; BH3 Interacting Domain Death Agonist Protein; Caspase 3; Caspase 8; Cell Cycle; Cell Death; Cell Line, Tumor; Cytochromes c; Cytosol; Down-Regulation; Humans; Membrane Potential, Mitochondrial; Mitochondria; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Propidium; Proto-Oncogene Proteins c-bcl-2; Terpenes

ABT-737 is a BH3 mimetic small-molecule inhibitor that binds with high affinity to Bcl-2 to induce apoptosis in malignant cells and has shown promise as an effective anti-leukemic agent in pediatric preclinical tests. This study focuses on the effects of ABT-737 on leukemia cells with MLL rearrangement and identifies some of the biological correlates of its activity.. Cells were cultured in the presence of increasing concentrations of ABT-737 alone or in combination with other agents. After 4 days in culture, cell growth inhibition was measured by Alamar blue assay. The expression and activation of potential intracellular targets of ABT-737 activity were determined by Western blot analysis.. Significant Bcl-2 expression was detected in all infant leukemia cells investigated. ABT-737 induced cell death in all cell lines studied although the IC(50) values differed somewhat between cell lines. Western blot analysis identified the effects of ABT-737 on survival and apoptosis-regulatory proteins PARP, caspase-8, and cytochrome-c. Drug combination studies indicated synergy with distinct anti-neoplastic agents, including the multi-tyrosine kinase inhibitor sunitinib. This effective drug synergy appears to be mediated by the combined inhibition of Bcl-2 and intracellular signaling pathways.. We describe the in vitro studies to demonstrate the activity and drug combinability of ABT-737 against MLL rearranged leukemia cells. In addition, identification of the molecular changes that occur in the presence of ABT-737 provides information regarding effective target validation and target modulation analyses in future clinical trials.

Topics: Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Blotting, Western; Caspase 8; Cell Line, Tumor; Cytochromes c; Drug Combinations; Gene Rearrangement; Histone-Lysine N-Methyltransferase; Humans; Infant; Male; Myeloid-Lymphoid Leukemia Protein; Nitrophenols; Piperazines; Poly(ADP-ribose) Polymerases; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2; Sulfonamides

Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein (P-gp) is one of the major impediments to successful treatment of cancer. P-gp acts as an energy-dependent drug efflux pump and reduces the intracellular concentration of structurally unrelated drugs inside the cells. Therefore, there is an urgent need for development of new molecules that are less toxic to normal cell and preferentially effective against drug resistant malignant cells. In this preclinical study we report the apoptotic potential of copper N-(2-hydroxyacetophenone) glycinate (CuNG) on doxorubicin resistant T lymphoblastic leukaemia cells (CEM/ADR5000). To evaluate the cytotoxic effect of CuNG, we used different normal cell lines (NIH 3T3, Chang liver and human PBMC) and cancerous cell lines (CEM/ADR5000, parental sensitive CCRF-CEM, SiHa and 3LL) and conclude that CuNG preferentially kills cancerous cells, especially both leukemic cell types irrespective of their MDR status, while leaving normal cell totally unaffected. Moreover, CuNG involves reactive oxygen species (ROS) for induction of apoptosis in CEM/ADR5000 cells through the intrinsic apoptotic pathway. This is substantiated by our observation that antioxidant N-acetyle-cysteine (NAC) and PEG catalase could completely block ROS generation and, subsequently, abrogates CuNG induced apoptosis. On the other hand, uncomplexed ligand N-(2-hydroxyacetophenone) glycinate (NG) fails to generate a significant amount of ROS and concomitant induction of apoptosis in CEM/ADR5000 cells. Therefore, CuNG induces drug resistant leukemia cells to undergo apoptosis and proves to be a molecule having therapeutic potential to overcome MDR in cancer.

Topics: Animals; Antibiotics, Antineoplastic; Apoptosis; Blotting, Western; Cell Cycle; Cell Line; Cell Line, Tumor; Cell Survival; Cells, Cultured; Copper; Cytochromes c; Dose-Response Relationship, Drug; Doxorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Flow Cytometry; Glutathione; Glycine; Humans; Mice; NIH 3T3 Cells; Organometallic Compounds; Oxidation-Reduction; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Reactive Oxygen Species; Time Factors

The antiproliferative effects of 15-LOX (15-lipoxygenase) metabolites of arachidonic acid {(15S)-HPETE [(15S)-hydroperoxyeicosatetraenoic acid] and (15S)-HETE [(15S)-hydroxyeicosatetraenoic acid]} and the mechanism(s) involved were studied in the human T-cell leukaemia cell line Jurkat. (15S)-HPETE, the hydroperoxy metabolite of 15-LOX, inhibited the growth of Jurkat cells 3 h after exposure and with an IC(50) value of 10 microM. The hydroxy metabolite of 15-LOX, (15S)-HETE, on the other hand, inhibited the growth of Jurkat cells after 6 h of exposure and with an IC(50) value of 40 microM. The cells exposed to 10 microM (15S)-HPETE for 3 h or to 40 microM (15S)-HETE for 6 h showed increased expression of Fas ligand and FADD (Fas-associated death domain), caspase 8 activation, Bid (BH3-interacting domain death agonist) cleavage, decrease in mitochondrial membrane potential, cytochrome c release, caspase 3 activation, PARP-1 [poly(ADP-ribose) polymerase-1] cleavage and DNA fragmentation, suggesting the involvement of both extrinsic and intrinsic death pathways. Further studies on ROS (reactive oxygen species) generation revealed the involvement of NADPH oxidase. In conclusion, the present study indicates that NADPH oxidase-induced ROS generation activates the Fas-mediated death pathway.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Arachidonate 15-Lipoxygenase; Caspases; Cell Cycle; Cell Death; Cell Proliferation; Cytochromes c; DNA Fragmentation; Enzyme Activation; Fas Ligand Protein; fas Receptor; Flow Cytometry; Humans; Jurkat Cells; Leukotrienes; Lipid Peroxides; Membrane Potential, Mitochondrial; NADPH Oxidases; Poly(ADP-ribose) Polymerases; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-akt; Reactive Oxygen Species; Signal Transduction; Stereoisomerism

We have previously demonstrated induction of O-acetylated sialoglycoproteins on lymphoblasts of childhood acute lymphoblastic leukaemia (ALL). These molecules promote survival of lymphoblasts by preventing apoptosis. Although O-acetylated sialoglycoproteins are over expressed, the status of O-acetylation of gangliosides and their role in lymphoblasts survival remains to be explored in ALL patients. Here, we have observed enhanced levels of 9-O-acetylated GD3 (9-O-AcGD3) in the lymphoblasts of patients and leukaemic cell line versus disialoganglioside GD3 in comparison to the normal cells. Localization of GD3 and 9-O-AcGD3 on mitochondria of patient's lymphoblasts has been demonstrated by immuno-electron microscopy. The exogenous administration of GD3-induced apoptosis in lymphoblasts as evident from the nuclear fragmentation and sub G0/G1 apoptotic peak. In contrast, 9-O-AcGD3 failed to induce such apoptosis. We further explored the mitochondria-dependent pathway triggered during GD3-induced apoptosis in lymphoblasts. GD3 caused a time-dependent depolarization of mitochondrial membrane potential, release of cytochrome c and 7.4- and 8-fold increased in caspase 9 and caspase 3 activity respectively. However, under identical conditions, an equimolar concentration of 9-O-AcGD3 failed to induce similar effects. Interestingly, 9-O-AcGD3 protected the lymphoblasts from GD3-induced apoptosis when administered in equimolar concentrations simultaneously. In situ de-O-acetylation of 9-O-AcGD3 with sodium salicylate restores the GD3-responsiveness to apoptotic signals. Although both GD3 and 9-O-acetyl GD3 localize to mitochondria, these two structurally related molecules may play different roles in ALL-disease biology. Taken together, our results suggest that O-acetylation of GD3, like that of O-acetylated sialoglycoproteins, might be a general strategy adopted by leukaemic blasts towards survival in ALL.

Topics: Acetylation; Apoptosis; Caspase 3; Cell Cycle; Cell Survival; Cytochromes c; Gangliosides; Humans; Lymphocytes; Membrane Potential, Mitochondrial; Microscopy, Confocal; Microscopy, Immunoelectron; Precursor Cell Lymphoblastic Leukemia-Lymphoma

ABT-737 is a pan-Bcl-2 inhibitor that has a wide range of single-agent activity against acute lymphoblastic leukemia (ALL) cell lines and xenografts. A relationship between expression of myeloid cell leukemia 1 (Mcl-1), an antiapoptotic member of the Bcl-2 family of proteins, and resistance to ABT-737 has been reported for various cancers. The synthetic cytotoxic retinoid N-(4-hydroxyphenyl)retinamide (4-HPR) is known to generate reactive oxygen species (ROS), and ROS have been shown to activate c-Jun kinase (JNK), which in turn phosphorylates and inhibits Mcl-1. Thus, we investigated whether 4-HPR-mediated inactivation of Mcl-1 could act synergistically with ABT-737 to promote leukemia cell death.. Cytotoxicity was determined using the fluorescence-based DIMSCAN assay. Synergy was defined as a combination index (CIN) less than 1. The expression of Bcl-2 family messenger RNAs was measured by real-time reverse transcription-polymerase chain reaction, and caspase activity was measured enzymatically. Changes in Bcl-2 family proteins and release of mitochondrial cytochrome c were detected by immunoblotting. ROS, apoptosis, mitochondrial membrane depolarization, and phospho-JNK were measured by flow cytometry. Gene silencing was by small interfering RNA (siRNA). All statistical tests were two-sided.. ABT-737 decreased Mcl-1 protein expression in ABT-737-sensitive ALL cell lines but not in ABT-737-resistant lines. Using the antioxidant ascorbic acid and siRNA-mediated knockdown of JNK, we showed that 4-HPR decreased Mcl-1 via ROS generation (that phosphorylates JNK) in ABT-737-resistant cell lines. Combining ABT-737 with 4-HPR enhanced the mitochondrial apoptotic cascade (percentage of cells with depolarized mitochondrial membrane at 6 hours, ABT-737 vs ABT-737 plus 4-HPR: 24.5% vs 45.5%, difference = 20.1%, 95% CI = 18.9% to 13.9%; P < .001) and caused caspase-dependent, synergistic multilog cytotoxicity in all seven ALL cell lines examined (mean CIN = 0.57, 95% CI = 0.37 to 0.87), with minimal cytotoxicity for normal lymphocytes.. An increase of Mcl-1 protein in response to ABT-737 is one mechanism of ABT-737 resistance that can be overcome by 4-HPR, resulting in synergistic cytotoxicity of ABT-737 combined with 4-HPR in ALL cell lines.

Topics: Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Caspases; Cell Line, Tumor; Cytochromes c; Drug Synergism; Enzyme Activation; Fenretinide; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Gene Silencing; Humans; Immunoblotting; JNK Mitogen-Activated Protein Kinases; Mitochondrial Membranes; Nitrophenols; Phosphorylation; Piperazines; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; Sulfonamides

This work shows that 25 microM quercetin caused a marked inhibition of K562 cells growth together with a mild cytotoxicity, while HSB-2 cells were practically unaffected. Moreover, quercetin induced caspase-3 and cytochrome c-dependent apoptosis almost exclusively in the former cell line. Exposure of K562 cells to quercetin caused also a significant increase of cells in G(2)/M phase that reached the maximum peak at 24 h (4-fold with respect to the basal value). The major sensitivity exhibited by K562 cells was only in part imputable to their higher glutathione content, as compared to HSB-2 cells, thus confirming previous reports describing the formation of intracellular quercetin-thiol toxic adducts in cells exposed to the flavonoid. In fact, after induction of intracellular glutathione increase we detected in both cell lines a significant rise of apoptotic cells, again more marked in K562 cells. By contrast, glutathione-depleted cells, failed to show a decrease of apoptosis in both cell lines, thus contradicting our previous findings and literature data. Since the yet unresolved question about the anti-oxidant or the pro-oxidant capacity of quercetin, we investigated which of these two properties worked in our experimental model. Interestingly, not only quercetin did not produce reactive oxygen species but also prevented their formation, as observed in cells exposed to the oxidizing agent ter-butylhydroperoxide, acting as an efficient oxygen radicals scavenger. This result indicates that quercetin exhibited, in these cell lines, anti-oxidant more than pro-oxidant ability.

Topics: Animals; Apoptosis; Caspases; Cell Cycle; Cell Line, Tumor; Cell Survival; Cytochromes c; Dose-Response Relationship, Drug; Enzyme Activation; Glutathione; Humans; K562 Cells; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Quercetin; Reactive Oxygen Species

Defects in apoptosis signaling contribute to poor outcome in pediatric acute lymphoblastic leukemia (ALL), and overexpression of antiapoptotic Bcl-2 (Bcl-2 and Bcl-X(L)) family proteins has been observed in ALL. ABT-737 is a small-molecule BH3-mimetic that inhibits the antiapoptotic Bcl-2 family proteins. We evaluated the cytotoxicity of ABT-737 in combination with vincristine, dexamethasone, and L-asparaginase (VXL) in 7 ALL cell lines. Multilog synergistic cytotoxicity was observed in all 7 cell lines with ABT-737 plus L-asparaginase or vincristine, and in 5 of 7 cell lines with ABT-737 plus dexamethasone or VXL. In leukemia cells, but not in normal lymphocytes, ABT-737 plus L-asparaginase induced greater mitochondrial depolarization (JC-1 staining); mitochondrial cytochrome c release; activation of Bax, Bid, and caspases (immunoblotting); and eventually apoptosis (annexin V staining) than did either drug alone. In mouse xenografts derived from patients with ALL at diagnosis (ALL-7) or at relapse (ALL-19), event-free survival (EFS) was significantly enhanced with ABT-737 plus VXL relative to VXL or ABT-737 alone (P

Topics: Animals; Anti-Inflammatory Agents; Antineoplastic Agents; Apoptosis; Asparaginase; Biphenyl Compounds; Blotting, Western; Cell Line, Tumor; Child; Cytochromes c; Dexamethasone; Drug Therapy, Combination; Female; Flow Cytometry; Humans; In Vitro Techniques; Leukemia, T-Cell; Membrane Potential, Mitochondrial; Mice; Mice, Inbred NOD; Mice, SCID; Mitochondria; Nitrophenols; Piperazines; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2; Sulfonamides; Survival Rate; Vincristine

Altered or deficient activation of apoptosis signalling pathways may contribute to drug resistance. Here, we assess the role of apoptotic mediators in eliciting an anti-proliferative response to paclitaxel (PTX) in a T cell acute lymphoblastic leukemia (ALL) cell line CEM and its epothilone-paclitaxel resistant sub-line CEM/dEpoB300. Furthermore, the cellular response to PTX was compared to those elicited by cells in response to treatment with albendazole (ABZ; a microtubule depolymerizing agent). In cell proliferation studies, CEM cells were sensitive to both PTX and ABZ, while the CEM/dEpoB300 cells were highly resistant to PTX (IC(50) 2.86 nM versus 30.26 nM, respectively). In contrast, the resistant cells showed a 2-fold increase in sensitivity to ABZ (0.32 microM in CEM compared to 0.16 microM in CEM/dEpoB300). Analysis of caspase-3 activity and cytochrome c release in response to PTX or ABZ treatment (24, 48 and 72 h) revealed that, compared to the parent cells, the resistant cells have diminished response to PTX and enhanced response to ABZ. A similar pattern was observed for the pro-apoptotic protein Bax. Levels of the anti-apoptotic protein Bcl-2 was highly elevated in CEM/dEpoB300 cells and in these cells, ABZ was more effective in lowering the Bcl-2 levels than PTX. Similarly, ABZ treatment led to profound down regulation of the Mcl-1 protein. These results reveal for the first time, the changes in apoptotic mediators following development of resistance to PTX in an ALL cell and the significantly increased sensitivity of these PTX resistant cells to ABZ.

Topics: Albendazole; Apoptosis; Base Sequence; bcl-2-Associated X Protein; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cytochromes c; DNA Primers; Epothilones; Humans; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasm Proteins; Paclitaxel; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2; Tumor Suppressor Protein p53

Deficient activation of apoptosis signaling pathways may be responsible for treatment failure in acute leukemia. Here, we address the impact of intact apoptosis signaling in 78 patients with pediatric precursor B-cell acute lymphoblastic leukemia (ALL) by analysis of 2 key apoptogenic events: caspase-3 activation and cytochrome c release in leukemia cells cultured in vitro. Both events correlated only in the group of patients who had a good response and patients in continuous remission, suggesting that intact apoptosis signaling is a characteristic for favorable outcome. By combining both parameters, we identified a novel indicator, cytochrome c-related activation of caspase-3 (CRAC). CRAC directly connects the extent of caspase-3 activation to cytochrome c release in single cells in an individual patient sample. In CRAC-positive patients, indicating proficient apoptosis signaling, the number of persisting leukemia cells on day 15 was significantly lower than in the CRAC-negative patient group (n = 27, mean 6.0% versus n = 36, mean 22.6%; P = .003). At a median follow-up of 31 months, disease-free survival was 84 months (95% CI = 76 to 91 months) and 66 months (95% CI = 52 to 80 months) for patients with positive and negative CRAC, respectively (P = .019). CRAC may serve as a functionally defined risk factor for treatment stratification.

Topics: Adolescent; Apoptosis; Caspase 3; Caspases; Cell Count; Child; Child, Preschool; Cytochromes c; Flow Cytometry; Humans; Infant; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Prognosis; Recurrence; Risk Assessment; Treatment Outcome

To investigate the anticancer effects and molecular mechanism of artonin B on the human acute lymphoblastic leukemia CCRF-CEM cells compared with other prenylflavonoid compounds.. The effects of four prenylflavonoids on the growth of CCRF-CEM and HaCa cells were studied by 3-(4,5)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Apoptosis were detected through Hoechst 33258 staining. The effect of artonin B on the cell cycle of CCRF-CEM cells were studied by propidium iodide method. The change in mitochondrial membrane potential was detected by rohdamine 123 staining. The cytochrome c release and caspase 3 activity were checked by immunoassay kits, respectively. The expression of Bcl-2 family proteins was detected by Western blot.. Our data revealed that artonin B strongly induced human CCRF-CEM leukemia cell death in a dose- and time-dependent manner by MTT assay, but not on normal epithelia cells (HaCa cells). Artonin B-induced cell death was considered to be apoptotic by observing the typical apoptotic morphological change by Hoechst 33258 staining. The induction of human CCRF-CEM leukemia cancer cell death was caused by an induction of apoptosis through mitochondrial membrane potential change, cytochrome c release, sub-G1 proportion increase, downregulation of Bcl-2 expression, upregulation of Bax and Bak expression and activation of caspase 3 pathways.. These results clearly demonstrated that artonin B is able to inhibit proliferation by induction of hypoploid cells and cell apoptosis. Moreover, the anticancer effects of artonin B were related to mitochondrial pathway and caspase 3 activation in human CCRF-CEM leukemia cells.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Artocarpus; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; Caspase 3; Cell Line, Tumor; Cytochromes c; Flavones; Flavonoids; HeLa Cells; Humans; Membrane Potentials; Mitochondria; Molecular Structure; Plant Roots; Plants, Medicinal; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2

Beauvericin (BEA), a cyclic hexadepsipeptide, induces cell death in human leukemia cells (CCRF-CEM) and the process of BEA-induced cell death has been speculated to undergo an apoptotic pathway. In the present study, several well-characterized factors, known to play important roles in apoptotic pathway, were investigated in BEA-induced CCRF-CEM cell death. CCRF-CEM cells were treated with BEA at concentrations from 1 to 10 microM for up to 24 h. The incidence of nuclear fragmentation and apoptotic body formation in the cells, cytosolic caspase-3 activity, mitochondrial membrane potential, and release of cytochrome c (Cyt c) from mitochondria in BEA-treated cells were determined and compared with that in untreated cells. Moreover, to investigate the role of intracellular Ca++ in this cell death process, CCRF-CEM cells were primed with 3 microM of BAPTA/AM, a Ca++ chelator, to exclude intracellular Ca++ prior to the BEA treatment. The data revealed that BEA-induced cell death in CCRF-CEM cells exhibited a dose- and time-dependent manner. The incidence of nuclear fragmentation and apoptotic body formation was significantly increased in CCRF-CEM cells treated with BEA at concentrations of 1 microM or greater. Increase of cytosolic caspase-3 activity was also observed in BEA-treated cells with a dose-dependent manner. In addition, increased release of Cyt c from mitochondria was also observed in the cells treated with 10 microM BEA in a time-dependent pattern. The BAPTA/AM pretreatment partially blocked BEA-induced cell death in CCRF-CEM cells, indicating that intracellular Ca++ plays an important role, maybe as a mediator in cell death signaling, in this cell death pathway. The results support the notion that BEA-induced cell death in CCRF-CEM cells likely undergo through an apoptotic pathway on the basis of increase of release of Cyt c from mitochondria, increase of caspase-3 activity, and some observed typical apoptotic cellular changes in morphology.

Topics: Apoptosis; Calcium; Caspase 3; Caspases; Cell Death; Cell Line, Tumor; Chelating Agents; Cytochromes c; Cytosol; Depsipeptides; Dose-Response Relationship, Drug; Egtazic Acid; Humans; Morpholines; Precursor Cell Lymphoblastic Leukemia-Lymphoma