naphthoquinones and Leukemia

Novel derivatives of aminophenyl-1,4-naphthoquinones, in which a pyrrolidine group was added to the naphthoquinone ring, were synthesized and investigated for the mechanisms of leukemic cell killing. The novel compounds, TW-85 and TW-96, differ in the functional (methyl or hydroxyl) group at the para-position of the aminophenyl moiety. TW-85 and TW-96 were found to induce concentration- and time-dependent apoptotic and/or necrotic cell death in human U937 promonocytic leukemia cells but only TW-96 could also kill K562 chronic myeloid leukemia cells and CCRF-CEM lymphoblastic leukemia cells. Normal peripheral blood mononuclear cells were noticeably less responsive to both compounds than leukemia cells. At low micromolar concentrations used, TW-85 killed U937 cells mainly by inducing apoptosis. TW-96 was a weaker apoptotic agent in U937 cells but proved to be cytotoxic and a stronger inducer of necrosis in all three leukemic cell lines tested. Both compounds induced mitochondrial permeability transition pore opening, cytochrome c release, and caspase activation in U937 cells. Cytotoxicity induced by TW-96, but not by TW-85, was associated with the elevation of the cytosolic levels of reactive oxygen species (ROS). The latter was attenuated by diphenyleneiodonium, indicating that NADPH oxidase was likely to be the source of ROS generation. Activation of p38 MAPK by the two agents appeared to prevent necrosis but differentially affected apoptotic cell death in U937 cells. These results further expand our understanding of the structure-activity relationship of aminophenyl-1,4-naphthoquinones as potential anti-leukemic agents with distinct modes of action.

Topics: Apoptosis; Cell Death; Humans; Leukemia; Leukemia, Myeloid; Leukocytes, Mononuclear; Naphthoquinones; Necrosis; Reactive Oxygen Species; U937 Cells

TMKS8A (1), a new chlorinated α-lapachone derivative, along with five known related metabolites, A80915 C (2), SF2415B1 (3), chlorinated dihydroquinone 3 (4), SF2415B3 (5), and A80915 C (6), were identified from the culture extract of Streptomyces sp. TMKS8, which was isolated from a sea slug, Paromoionchis tumidus. The structure of 1 was determined by the analysis of NMR and MS spectral data, assisted by NMR chemical shift prediction using DFT-based calculation. The absolute configuration was determined to be R by comparison of experimental and calculated ECD spectra. Compound 1 displayed antimicrobial activity against Gram-positive bacteria with MIC values ranging from 6.25 to 12.5 μg ml

Topics: Animals; Anti-Bacterial Agents; Aquatic Organisms; Cell Line, Tumor; Circular Dichroism; Drug Evaluation, Preclinical; Gastropoda; Gram-Positive Bacteria; Leukemia; Magnetic Resonance Spectroscopy; Mice; Microbial Sensitivity Tests; Molecular Structure; Naphthoquinones; Streptomyces

Antitumor effects of shikonins on chronic lymphocytic leukemia (CLL) and B-cell prolymphocytic leukemia (B-PLL) are mostly unexplored. The antitumor activity of shikonins, isolated from

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Boraginaceae; Cell Line; Cell Proliferation; Cell Survival; Gene Expression Regulation, Neoplastic; Humans; Inhibitory Concentration 50; Leukemia; Male; Membrane Proteins; Mice; Mice, Inbred BALB C; Naphthoquinones; Phosphoproteins; STAT3 Transcription Factor

Although YM155 is reported to suppress survivin (also known as BIRC5) expression in cancer cells, its cytotoxic mechanism in human acute myeloid leukemia (AML) cells has not been clearly resolved. In this study, we analyzed the mechanistic pathways that modulate the sensitivity of human AML U937 and HL-60 cells to YM155. YM155 induced apoptosis in AML cells, which was characterized by p38 MAPK phosphorylation and downregulation of survivin and MCL1 expression. Phosphorylated p38 MAPK causes autophagy-mediated Sp1 degradation, thereby inhibiting the transcription of survivin and MCL1. The reduction of survivin and MCL1 levels further facilitated Sp1 protein degradation through autophagy. The restoration of Sp1, survivin, or MCL1 expression protected U937 and HL-60 cells from YM155-mediated cytotoxicity. U937 and HL-60 cells were continuously exposed to hydroquinone (HQ) to generate U937/HQ and HL-60/HQ cells, which showed increased SLC35F2 expression. The increase in SLC35F2 expression led to an increase in the sensitivity of U937/HQ cells to YM155-mediated cytotoxicity, whereas no such effect was observed in HL-60/HQ cells. Of note, myeloperoxidase (MPO) activity in HL-60 and HL-60/HQ cells enhanced YM155 cytotoxicity in these cells, and the enforced expression of MPO also increased the sensitivity of U937 cells to YM155. Taken together, we conclude that p38 MAPK-modulated autophagy inhibits Sp1-mediated survivin and MCL1 expression, which, in turn, leads to the death of U937 and HL-60 cells following YM155 treatment. In addition, our data indicate that SLC35F2 increases the sensitivity of U937 cells to YM155-mediated cytotoxicity, whereas MPO enhances YM155 cytotoxicity in U937 and HL-60 cells.

Topics: Cell Survival; Cytotoxins; Dose-Response Relationship, Drug; Gene Expression Regulation, Neoplastic; HL-60 Cells; Humans; Imidazoles; Leukemia; Membrane Transport Proteins; Myeloid Cell Leukemia Sequence 1 Protein; Naphthoquinones; Peroxidase; Sp1 Transcription Factor; Survivin; U937 Cells

The aim of this study was to investigate the cytotoxic effect of new 1,4-naphthoquinone- 1,2,3-triazoles, named C2 to C8 triazole derivatives, towards human cancer cell lines.. The effect on cell viability was assessed by MTT and propidium iodide assays. The cytotoxic effect of C2 and C3 in K562 and HL-60 cells were analyzed by flow cytometry, DNA fragmentation and reactive oxygen species (ROS) production. Western blot and q-PCR procedures were also performed.. C2 and C3 inhibited both K562 and HL-60 cells growth in a concentration-dependent manner. C2 presented the highest cytotoxic activity with an IC50 of approximately 14 μm and 41 μm for HL-60 and K562 cells, respectively, while being less toxic to normal peripheral blood monocyte cells. Both derivatives induced cellular changes in HL-60 cells, characteristic of apoptosis, such as mitochondrial membrane depolarization, phosphatidylserine externalization, increasing sub-G1 phase, DNA fragmentation, downregulating Bcl-2 protein and upregulating Bax protein. In K562 cells, C2 and C3 induced S-phase arrest of cell cycle, which was associated with upregulation of p21. The effect of these derivatives in HL-60 cells can be related to the ROS intracellular level.. Taken together our results showed that C2 and C3 triazole derivatives presented the best potential for drug design.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Cell Cycle Proteins; Cell Proliferation; Cell Survival; DNA Fragmentation; Dose-Response Relationship, Drug; HL-60 Cells; Humans; Inhibitory Concentration 50; K562 Cells; Leukemia; Membrane Potential, Mitochondrial; Molecular Structure; Naphthoquinones; Oxidative Stress; Reactive Oxygen Species; S Phase Cell Cycle Checkpoints; Structure-Activity Relationship; Triazoles

Leukemia remains life-threatening despite remarkable advances in chemotherapy. The poor prognosis and drug resistance are challenging treatment. Novel drugs are urgently needed. Shikonin, a natural naphthoquinone, has been previously shown by us to be particularly effective towards various leukemia cell lines compared to solid tumors. However, the underlying mechanisms are still poorly understood. Here, we investigated shikonin and 14 derivatives on U937 leukemia cells. Four derivatives (isobutyrylshikonin, 2-methylbutyrylshikonin, isovalerylshikonin and β,β-dimethylacrylshikonin) were more active than shikonin. AnnexinV-PI analysis revealed that shikonins induced apoptosis. Cell cycle G1/S check point regulation and the transcription factor c-MYC, which plays a vital role in cell cycle regulation and proliferation, were identified as the most commonly down-regulated mechanisms upon treatment with shikonins in mRNA microarray hybridizations. Western blotting and DNA-binding assays confirmed the inhibition of c-MYC expression and transcriptional activity by shikonins. Reduction of c-MYC expression was closely associated with deregulated ERK, JNK MAPK and AKT activity, indicating their involvement in shikonin-triggered c-MYC inactivation. Molecular docking studies revealed that shikonin and its derivatives bind to the same DNA-binding domain of c-MYC as the known c-MYC inhibitors 10058-F4 and 10074-G5. This finding indicates that shikonins bind to c-MYC. The effect of shikonin on U937 cells was confirmed in other leukemia cell lines (Jurkat, Molt4, CCRF-CEM, and multidrug-resistant CEM/ADR5000), where shikonin also inhibited c-MYC expression and influenced phosphorylation of AKT, ERK1/2, and SAPK/JNK. In summary, inhibition of c-MYC and related pathways represents a novel mechanism of shikonin and its derivatives to explain their anti-leukemic activity.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Cell Line, Tumor; Extracellular Signal-Regulated MAP Kinases; Humans; JNK Mitogen-Activated Protein Kinases; Leukemia; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase Kinases; Naphthoquinones; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-myc; Signal Transduction; U937 Cells

Shikonin, a major active component of the Chinese herbal plant Lithospermum erythrorhizon, has been applied for centuries in traditional Chinese medicine. Although shikonin demonstrates potent anticancer efficacy in numerous types of human cancer cells, the cellular targets of shikonin have not been fully defined. We report here that shikonin may interact with the cytosolic thioredoxin reductase (TrxR1), an important selenocysteine (Sec)-containing antioxidant enzyme with a C-terminal -Gly-Cys-Sec-Gly active site, to induce reactive oxygen species (ROS)-mediated apoptosis in human promyelocytic leukemia HL-60 cells. Shikonin primarily targets the Sec residue in TrxR1 to inhibit its physiological function, but further shifts the enzyme to an NADPH oxidase to generate superoxide anions, which leads to accumulation of ROS and collapse of the intracellular redox balance. Importantly, overexpression of functional TrxR1 attenuates the cytotoxicity of shikonin, whereas knockdown of TrxR1 sensitizes cells to shikonin treatment. Targeting TrxR1 with shikonin thus discloses a previously unrecognized mechanism underlying the biological activity of shikonin and provides an in-depth insight into the action of shikonin in the treatment of cancer.

Topics: Antioxidants; Apoptosis; Cell Survival; Drugs, Chinese Herbal; Gene Knockdown Techniques; HL-60 Cells; Humans; Leukemia; Naphthoquinones; Reactive Oxygen Species; Thioredoxin-Disulfide Reductase

Plumbagin is a plant naphtoquinone exerting anti-cancer properties including apoptotic cell death induction and generation of reactive oxygen species (ROS). The aim of this study was to elucidate parameters explaining the differential leukemia cell sensitivity towards this compound. Among several leukemia cell lines, U937 monocytic leukemia cells appeared more sensitive to plumbagin treatment in terms of cytotoxicity and level of apoptotic cell death compared to more resistant Raji Burkitt lymphoma cells. Moreover, U937 cells exhibited a ten-fold higher ROS production compared to Raji. Neither differential incorporation, nor efflux of plumbagin was detected. Pre-treatment with thiol-containing antioxidants prevented ROS production and subsequent induction of cell death by apoptosis whereas non-thiol-containing antioxidants remained ineffective in both cellular models. We conclude that the anticancer potential of plumbagin is driven by pro-oxidant activities related to the cellular thiolstat.

Topics: Antineoplastic Agents, Phytogenic; Antioxidants; Apoptosis; Cell Line, Tumor; Cell Survival; Glutathione; Humans; Leukemia; Naphthoquinones; Oxidation-Reduction; Reactive Oxygen Species; U937 Cells

The cytotoxicity of a series of aminonaphthoquinones resulting from the reaction of suitable aminoacids with 1,4-naphthoquinone was assayed against SF-295 (glioblastoma), MDAMB-435 (breast), HCT-8 (colon), HCT-116 (colon), HL-60 (leukemia), OVCAR-8 (ovarian), NCI-H358M (bronchoalveolar lung carcinoma) and PC3-M (prostate) cancer cells and also against PBMC (peripheral blood mononuclear cells). The results demonstrated that all the synthetic aminonaphthoquinones had relevant cytotoxic activity against all human cancer lines used in this experiment. Five of the compounds showed high cytotoxicity and selectivity against all cancer cell lines tested (IC50 = 0.49 to 3.89 µg·mL-1). The title compounds were less toxic to PBMC, since IC50 was 1.5 to eighteen times higher (IC50 = 5.51 to 17.61 µg·mL-1) than values shown by tumour cell lines. The mechanism of cell growth inhibition and structure-activity relationships remains as a target for future investigations.

Topics: Cell Proliferation; Cytotoxins; Drug Screening Assays, Antitumor; HL-60 Cells; Humans; Leukemia; Leukocytes, Mononuclear; Naphthoquinones; Structure-Activity Relationship

Survivin, a member of the inhibitor of apoptosis protein (IAP) family, is highly expressed in various kinds of tumors. In the present study, we investigated the cytotoxic mechanism of YM155, a unique small-molecule inhibitor of survivin, in human myelogenous leukemia cells. YM155 potently inhibited the cell growth of HL-60 and U937 cells with the half-maximal inhibitory concentration (IC50) value of 0.3 nM and 0.8 nM, respectively. YM155 significantly suppressed the levels of mRNA expression and protein of survivin in HL-60 and U937 cells. In addition, we also found that YM155 down-regulated the level of Mcl-1, another critical anti-apoptotic protein, in both HL-60 and U937 cells. Treatment of HL-60 and U937 cells with YM155 induced apoptosis concomitant with the activation of caspase-8 and caspase-3. Interestingly, we have found that caspase-8 inhibitor Z-IETD-FMK strongly inhibited YM155-induced apoptosis in HL-60 and U937 cells. When cells were pretreated with Z-IETD-FMK, the activation of caspase-3 was completely abolished, suggesting that caspase-8 may be involved in the activation of caspase-3 during YM155-induced apoptosis. We demonstrated for the first time that YM155 induces caspase-8 dependent apoptosis through downregulation of survivin and Mcl-1 in human leukemia cells.

Topics: Apoptosis; Blotting, Western; Caspase 3; Caspase 8; Cell Proliferation; Cysteine Proteinase Inhibitors; Dose-Response Relationship, Drug; Down-Regulation; Enzyme Activation; Flow Cytometry; Gene Expression Regulation, Leukemic; HL-60 Cells; Humans; Imidazoles; Inhibitor of Apoptosis Proteins; Inhibitory Concentration 50; Leukemia; Molecular Structure; Myeloid Cell Leukemia Sequence 1 Protein; Naphthoquinones; Oligopeptides; Proto-Oncogene Proteins c-bcl-2; Reverse Transcriptase Polymerase Chain Reaction; Survivin; U937 Cells

Furonaphthoquinones are promising skeletons for anticancer drug molecules. In particular, methoxylated furonaphthoquinones are characteristic constituents of Tabebuia plants. In this research, we synthesized the furonaphthoquinones by effective one-pot cascade reactions of 3-phenyliodonio-1,2,4-trioxo-1,2,3,4-tetrahydronaphthalenides with 3-butyn-2-ol in the presence of palladium and cuprous catalysts via Sonogashira coupling and intramolecular cyclization. Furthermore, we demonstrated that the synthetic furonaphthoquinones showed moderate cytotoxicity against human leukemia U937 and HL-60 cells. Our work highlights the importance of furonaphthoquinones as antileukemic agents.

Topics: Antineoplastic Agents; Catalysis; Cell Line, Tumor; Cell Survival; Copper; Cyclization; HL-60 Cells; Humans; Leukemia; Naphthoquinones; Palladium; Tabebuia

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

Necrostatin-1 (Nec-1) inhibits necroptosis by allosterically inhibiting the kinase activity of receptor-interacting protein 1 (RIP1), which plays a critical role in necroptosis. RIP1 is a crucial adaptor kinase involved in the activation of NF-κB, production of reactive oxygen species (ROS) and the phosphorylation of mitogen activated protein kinases (MAPKs). NF-κB, ROS and MAPKs all play important roles in apoptotic signaling. Nec-1 was regarded as having no effect on apoptosis. Here, we report that Nec-1 increased the rate of nuclear condensation and caspases activation induced by a low concentration of shikonin (SHK) in HL60, K562 and primary leukemia cells. siRNA-mediated knockdown of RIP1 significantly enhanced shikonin-induced apoptosis in K562 and HL60 cells. Shikonin treatment alone could slightly inhibit the phosphorylation of ERK1/2 in leukemia cells, and the inhibitory effect on ERK1/2 was significantly augmented by Nec-1. We also found that Nec-1 could inhibit NF-κB p65 translocation to the nucleus at a later stage of SHK treatment. In conclusion, we found that Nec-1 can promote shikonin-induced apoptosis in leukemia cells. The mechanism by which Nec-1 sensitizes shikonin-induced apoptosis appears to be the inhibition of RIP1 kinase-dependent phosphorylation of ERK1/2. To our knowledge, this is the first study to document Nec-1 sensitizes cancer cells to apoptosis.

Topics: Active Transport, Cell Nucleus; Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Cell Nucleus; HL-60 Cells; Humans; Imidazoles; Indoles; K562 Cells; Leukemia; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Naphthoquinones; Nuclear Pore Complex Proteins; RNA-Binding Proteins; Transcription Factor RelA

Kinetics of the chaperone activity of proteins Hsp70 and Hdj1 were analyzed in human U-937 promonocytes during their response to heat shock or to treatment with the echinochrome triacetyl glucoside derivative U-133. To measure the chaperone activity of both proteins, a special test was developed for their recognition and binding of a denatured protein. Using this test, the chaperone activity could be concurrently estimated in large numbers of cellular or tissue extracts. We also estimated the contents of both chaperones in cells by immunoblotting. The values for contents of Hsp70 and Hdj1 obtained by two independent test systems coincided, and this suggested that the substrate-binding activity could change proportionally to the chaperone content in the protein mixture. Therefore, the test developed by us can be employed for high throughput screening of drugs activating cellular chaperones. The analysis of quantity and activity of two cellular chaperones during the cell response to heat stress or to the drug-like substance U-133 showed that both factors caused the accumulation of chaperones with similar kinetics. We conclude that the efficiency of drug preconditioning could be close to the efficiency of hyperthermia and that the high activity of chaperones could be retained in human cells for no less than 1.5 days.

Topics: Cell Line, Tumor; Glucosides; Heat-Shock Response; HSP40 Heat-Shock Proteins; HSP70 Heat-Shock Proteins; Humans; Kinetics; Leukemia; Molecular Chaperones; Naphthoquinones; Protein Binding

The pentacyclic 1,4-naphthoquinones 1a-d were cytotoxic (IC(50) approximately 2-7 microM) to human leukemic cell lines K562 (oxidative stress-resistant), Lucena-1 (MDR phenotype) and Daudi. Fresh leukemic cells obtained from patients, some with the MDR phenotype, were also sensitive to these compounds. The pentacyclic 1,4-naphthoquinones 1a and 1c induced apoptotic cell death in cells from leukemic patients as determined by flow cytometry. Conversely, the cell lines were highly insensitive to lapachol (2) and alpha-lapachone (3). Mitomycin-C inhibited cell proliferation at concentrations as low as 0.5 microM. The low toxicity against lymphocytes activated by phytohemagglutinin shows that these compounds are selective for the cancer cells studied. Previous data suggest that these compounds (1a-d) can be bioactivated in situ by reduction followed by rearrangement leading to enones, which are powerful alkylating agents. In contrast, lapachol (2) and beta-lapachone (3), which cannot be bioactivated by reduction, showed little activity against the same cell lines.

Topics: Cell Death; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Screening Assays, Antitumor; Humans; Inhibitory Concentration 50; Leukemia; Leukocytes, Mononuclear; Mitomycin; Naphthoquinones

(+)-Cordiaquinone J is a 1,4-naphthoquinone isolated from the roots of Cordia leucocephala that has antifungal and larvicidal effects. However, the cytotoxic effects of (+)-cordiaquinone J have never being explored. In the present study, the effect of (+)-cordiaquinone J on tumor cells viability was investigated, showing IC(50) values in the range of 2.7-6.6muM in HL-60 and SF-295 cells, respectively. Studies performed in HL-60 leukemia cells indicated that (+)-cordiaquinone J (1.5 and 3.0muM) reduces cell viability and 5-bromo-2-deoxyuridine incorporation after 24h of incubation. (+)-Cordiaquinone J showed rapid induction of apoptosis, as indicated by phosphatidylserine externalization, caspase activation, DNA fragmentation, morphologic changes, and rapid induction of necrosis, as indicated by the loss of membrane integrity and morphologic changes. (+)-Cordiaquinone J altered the redox potential of cells by inducing the depletion of reduced GSH intracellular content, the generation of reactive oxygen species and the loss of mitochondrial membrane potential. However, pre-treatment of cells with N-acetyl-l-cysteine abolished most of the observed effects related to (+)-cordiaquinone J treatment, including those involving apoptosis and necrosis induction.

Topics: Apoptosis; Caspase 3; Caspase 7; Cell Line, Tumor; Cordia; Glutathione; HL-60 Cells; Humans; Leukemia; Membrane Potential, Mitochondrial; Mitochondria; Naphthoquinones; Necrosis; Oxidative Stress; Plant Roots; Reactive Oxygen Species

Up-regulation of telomerase activity is associated with immortalization and unlimited cell division in most cancer cells. Therefore, telomerase represents a particularly attractive target for anticancer therapy. Recent reports have suggested that beta-lapachone (LAPA), the product of the South American Tabebuia avellanedae tree, inhibits growth of tumor cells. However, the underlying relationship between telomerase activity and apoptosis in response to LAPA exposure in leukemia cells remains poorly understood. In this study, we confirmed that LAPA treatment induces direct cytotoxicity in human leukemia cells (U937, K562, HL60, and THP-1) through activation of caspase-3 and subsequent cleavage of poly(ADP-ribose) polymerase. The observed induction of cell death was associated with decreased telomerase activity, which was ascribed to down-regulation of telomerase reverse transcriptase. Additionally, overexpression of anti-apoptotic Bcl-2 could not overcome the induction of apoptosis or the decreased telomerase activity in response to treatment of U937 cells with LAPA. We conclude that LAPA has a direct cytotoxic effect and the loss of telomerase activity in leukemia cells.

Topics: Apoptosis; Caspase 3; Cell Proliferation; Cell Survival; Down-Regulation; HL-60 Cells; Humans; K562 Cells; Leukemia; Naphthoquinones; Plant Extracts; Poly(ADP-ribose) Polymerases; Tabebuia; Telomerase; U937 Cells

1-(1,4-dihydro-5,8-dihydroxy-1,4-dioxonaphthalen-2-yl)-4-methylpent-3-enylfuran-2-caroxylate (SH-7), a new naphthoquinone compound, derived from shikonin, exhibited obvious inhibitory actions on topoisomerase II (Topo II) and topoisomerase I (Topo I), which were stronger than its mother compound shikonin. Notably, the SH-7's inhibitory potency on Topo II was much stronger than that on Topo I. In addition, SH-7 significantly stabilized Topo II-DNA cleavable complex and elevated the expression of phosphorylated-H2AX. The in vitro cell-based investigation demonstrated that SH-7 displayed wide cytotoxicity in diversified cancer cell lines with the mean IC(50) value of 7.75 microM. One important finding is SH-7 displayed significant cytotoxicity in the 3 MDR cell lines, with an average IC(50) value nearly equivalent to that of the corresponding parental cell lines. The average resistance factor (RF) of SH-7 was 1.74, which was much lower than those of reference drugs VP-16 (RF 145.92), ADR (RF 105.97) and VCR (RF 197.39). Further studies illustrated that SH-7 had the marked apoptosis-inducing function on leukemia HL-60 cells, which was validated to be of mitochondria-dependence. The in vivo experiments showed that SH-7 had inhibitory effects on S-180 sarcoma implanted to mice, SMMC-7721, BEL-7402 human hepatocellular carcinoma and PC-3 human prostate cancer implanted to nude mice. Taken together, these results suggest that SH-7 induces DSBs as a Topo II inhibitor, which was crucial to activate the apoptotic process, and subsequently accounts for its both in vitro and in vivo antitumor activities. The well-defined Topo II inhibitory activity, antitumor effects particularly with its obvious anti-MDR action, better solubility and less toxicity make SH-7 as a potential antitumor drug candidate for further research and development.

Topics: Animals; Antineoplastic Agents; Apoptosis; Blotting, Western; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Electrophoresis, Agar Gel; Female; Flow Cytometry; Humans; Leukemia; Liver Neoplasms; Male; Mice; Mice, Nude; Naphthoquinones; Neoplasms; Prostatic Neoplasms; Sarcoma; Topoisomerase II Inhibitors; Transplantation, Heterologous

The cytotoxicity of naphthazarin derivatives isolated from the roots of Onosma arenaria on human cervix adenocarcinoma cells (HeLa) and leukaemia K562 cells, as well on non-malignant peripheral blood mononuclear cells (PBMC) was studied. The results show that beta-hydroxyisovalerylalkannin, acetylalkannin and the pigment fraction exhibited high cytotoxicity in vitro against the tested cell lines, as well the healthy PBMC before or after activation with phytohaemagglutinin.

Topics: Adenocarcinoma; Antineoplastic Agents, Phytogenic; Boraginaceae; Cell Line, Tumor; Female; Humans; Inhibitory Concentration 50; Leukemia; Leukocytes, Mononuclear; Naphthoquinones; Phytohemagglutinins; Phytotherapy; Plant Roots; Uterine Cervical Neoplasms

2-methyl-naphtho[2,3-b]furan-4,9-dione (FNQ3), a synthetic analogue of the quinone kigelinone, has demonstrated a real potential for use in the treatment of a variety of solid tumours. Unlike other quinones, such as mitomycin-C and adriamycin, the cytotoxicity of FNQ3 is often 10- to 14-fold more potent towards the tumour cells than their normal counterparts. We report, for the first time, that the drug had activity against a broad spectrum of leukaemias and multiple myeloma cells. It decreased the growth of acute myeloid leukaemia (AML) and multiple myeloma cell lines in a dose-dependent fashion (50% inhibitory concentration approximately 1.25 microg/ml against most of the leukaemia cell lines). This dose apparently initiated mitochondrial collapse as measured by depolarisation of the mitochondrial membrane. FNQ3 potentiated the differentiation of HL-60 myeloid cells in the presence of either 1alpha, 25(OH)(2) dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)] or all-trans-retinoic acid (ATRA). FNQ3 inhibited the proliferation of primary AML cells while inducing apoptosis. Eleven of 14 (79%) AML marrow samples had a prominent decrease in their clonogenic growth when cultured in the presence of the drug. In summary, this drug has growth inhibitory, apoptotic and differentiative effects against myeloid leukaemias and multiple myeloma cells. FNQ3 may represent a new therapeutic approach to these malignancies.

Topics: Antineoplastic Agents; Apoptosis; Cell Differentiation; Cell Division; Dose-Response Relationship, Drug; Humans; Leukemia; Membrane Potentials; Mitochondrial Membranes; Multiple Myeloma; Naphthoquinones; Tumor Cells, Cultured

Salvicine is a novel topoisomerase II inhibitor possessing significant antitumor activity, both in vitro and in vivo. The antitumor effect of salvicine is associated with its ability to induce tumor cell apoptosis. Telomerase plays an important role in the apoptotic pathway. However, little is known about the mechanisms of telomerase regulation during apoptosis induced by anticancer drugs. This study investigated the regulation of telomerase activity in salvicine-induced human leukemia HL-60 cell apoptosis. Salvicine treatment resulted in HL-60 cell apoptosis and down-regulation of telomerase activity in a time- and concentration-dependent manner. Repression of telomerase activity preceded a decrease in expression of the telomerase catalytic subunit (hTERT) and telomerase-associated protein (TP1) at the mRNA level, suggesting that the salvicine-induced decrease in telomerase activity may be additionally regulated by mechanisms other than telomerase subunit transcription. We observed that okadaic acid (OA), a protein phosphatase inhibitor, prevented the induction of apoptosis and the down-regulation of telomerase activity by salvicine. The significant increase in protein phosphatase 2A (PP2A) activity induced by salvicine treatment was blocked completely by OA. Moreover, although salvicine induced HL-60 cell apoptosis in a caspase-3-dependent manner, a specific caspase-3 inhibitor, Z-DEVD-FMK, did not prevent a decrease in telomerase activity or an increase in PP2A activity in apoptotic HL-60 cells, ruling out a role for caspase-3 in PP2A activation by salvicine. The results collectively suggest that the salvicine-induced decline in telomerase activity is not a consequence of HL-60 cell apoptosis and that it may be caused principally by the dephosphorylation of telomerase components mediated by PP2A activation.

Topics: Apoptosis; Caspase Inhibitors; Down-Regulation; Drug Interactions; Enzyme Activation; Enzyme Inhibitors; HL-60 Cells; Humans; Leukemia; Naphthoquinones; Okadaic Acid; Phosphoprotein Phosphatases; Phosphorylation; Protein Phosphatase 2; Telomerase

Dichloroallyl lawsone (DCL, NSC-126771), a synthetic analogue of the antimalarial lapachol, is potentially useful in cancer chemotherapy. Unlike most anticancer agents, DCL is not significantly myelosuppressive in animals but it induces acute cardiac toxicity in the rhesus monkey. This cardiac toxicity seems to be correlated with the maximal plasma DCL concentration, about 130 mg/L in the monkey. We have studied DCL pharmacokinetics in patients in an attempt to define safe dose limits for the Phase I clinical trial. After the rapid intravenous infusion of 10 mg/m2 of radioactive [1- or 4-14C]DCL, 250 muCi per patient, the mean peak plasma concentration of unchanged DCL in four patients was 2.9 +/- 0.3 mg/L. The drug had a mean initial plasma half-life of 48.9 +/- 19 min and a terminal half-life of 20.3 +/- 1.8 hr, with a C X t of 50.1 +/- 12 mg/L/hr, and a clearance rate of 0.08 ml/kg/min. These data suggest that in clinical trials the DCL dose given by rapid intravenous infusion should not exceed 450 mg/m2 so that the maximal plasma drug concentration remains below 130 mg/L.

Topics: Antineoplastic Agents; Dose-Response Relationship, Drug; Half-Life; Humans; Infusions, Parenteral; Kinetics; Leukemia; Naphthoquinones; Neoplasms

Topics: Animals; Antifibrinolytic Agents; Characidae; Leukemia; Leukemia, Lymphoid; Naphthoquinones; Neoplasms; Neoplasms, Experimental; Sodium; Tritium; Vitamin K