The role of bioreductive activation of antitumour anthracycline drugs in cytotoxic activity against sensitive and multidrug resistant leukaemia HL60 cells

Clinical usefulness of anthracyclines belonging to bioreductive antitumour drugs is limited by the occurrence of multidrug resistance (MDR). The aim of this study was to examine the role of structural factors of antitumour anthracycline drugs in the ability to undergo bioreductive activation by NADPH cytochrome P450 reductase (CPR) and determine the impact of this activation on increasing the activity especially in regard to MDR tumour cells. It was evidenced that at high NADPH concentration (500 μM) anthracyclines having non-modified quinone structure: doxorubicin (DOX), daunorubicin (DR) and idarubicin (IDA) were susceptible upon CPR catalysis to undergo a multi-stage chemical transformation concerning their chromophore part. Additionally, it was evidenced that the modification of the sugar moiety of DOX did not disturb the susceptibility of the obtained derivative (4'-O-tetrahydropyranyl-doxorubicin, pirarubicin, PIRA) to undergo CPR reductive activation. It was also evidenced that the derivatives having modified quinone groupment (5-iminodaunorubicin, 5-Im-DR) were not able to undergo reductive activation by CPR. The high impact of CPR-dependent reductive activation of anthracycline drugs on increasing the activity in regard to sensitive leukaemia HL60 cell line and its MDR sublines overexpressing P-glycoprotein (HL60/VINC) and MRP1 (HL60/DOX) was evidenced. Furthermore, significant changes in binding manner of activated compounds to naked DNA and cellular nucleus in comparison to their non-activated forms were also observed. It could prevent the export of formed adducts out of the cell by MDR proteins and may explain significant increases in intracellular accumulation of these compounds in HL60/VINC and HL60/DOX cells.     

抗三尖杉酯碱的HL60细胞抗粉防己碱诱导的细胞凋亡

抗三尖杉酯碱的ＨＬ６０细胞抗粉防己碱诱导的细胞凋亡１何琪杨，张鸿卿，庞大本２，池旭生２，薛绍白３（北京师范大学生物系，北京１００８７５；２中国中医研究院基础理论研究所，北京１００７００，中国）目的：用粉防己碱（Ｔｅｔ）研究抗三尖杉酯碱（Ｈａｒ）的ＨＬ...     

The ability of selected pyridinium salts to increase the cytotoxic activity of vincristine but not doxorubicin towards sensitive and multidrug resistant promyelocytic leukaemia HL60 cells

The aim of this study was to examine the effect of selected pyridinium salts, 1-methyl-3-nitropyridine chloride (MNP(+)Cl(-)) and 3,3,6,6,10-pentamethyl-3,4,6,7-tetrahydro-[1,8(2H,5H)-dion]acridine chloride (MDION(+)Cl(-)), on the activity of doxorubicin (DOX) and vincristine (VINC) towards human promyelocytic leukaemia HL60 cells as well as its multidrug resistant (MDR) sublines exhibiting two different phenotypes of MDR related to the overexpression of P-glycoprotein (HL60/VINC) or MRP1 (HL60/DOX). MNP and MDION salts were much less cytotoxic themselves (about 100-fold and 2000-fold compared with DOX and VINC, respectively) against HL60 cells but, in contrast to DOX and VINC, they conserved an important cytotoxic activity towards resistant HL60/VINC and HL60/DOX cells (resistance factor, RF = 2-4.5). It was shown that MNP(+)Cl(-) and MDION(+)Cl(-) increased the cytotoxicity of non-bioreductive antitumour agent VINC towards human promyelocytic leukaemia HL60 cells and its resistant sublines HL60/VINC and HL60/DOX. However, in the case of DOX the decrease in its cytotoxic activity towards all studied cell lines was observed in the presence of MNP(+)Cl(-) and MDION(+)Cl(-). Presented data suggest that the bioreductive drug DOX, in contrast to VINC, could compete with pyridinium salts (MNP(+)Cl(-) and MDION(+)Cl(-)) for NADPH-dependent oxidoreductases and for undergoing cellular reductive activation. This could explain the inefficiency of these salts to increase the cytotoxic activity of DOX against examined leukaemic HL60 cell line and its MDR sublines, HL60/VINC and HL60/DOX.     

Fisetin induces apoptosis in human cervical cancer HeLa cells through ERK1/2-mediated activation of caspase-8-/caspase-3-dependent pathway

Fisetin is a naturally occurring flavonoid that has been reported to inhibit the proliferation and to induce apoptotic cell death in several tumor cells. However, the apoptosis-inducing effect of fisetin on tumor cell lines was investigated besides HeLa cells. In this study, we found that fisetin induced apoptosis of HeLa cells in a dose- and time-dependent manner, as evidenced by nuclear staining of 4′-6-Diamidino-2-phenylindole (DAPI), flow cytometry assay, and Annexin-V/PI double-labeling. In addition, fisetin triggered the activations of caspases-3 and -8 and the cleavages of poly (ADP-ribose) polymerase, resulting in apoptosis induction. Moreover, treatment of HeLa cells with fisetin induced a sustained activation of the phosphorylation of ERK1/2, and inhibition of ERK1/2 by PD98059 (MEK1/2 inhibitor) or transfection with the mutant ERK1/2 expression vector significantly abolished the fisetin-induced apoptosis through the activation of caspase-8/-3 pathway. The in vivo xenograft mice experiments revealed that fisetin significantly reduced tumor growth in mice with HeLa tumor xenografts. In conclusion, our results indicated that fisetin exhibited anti-cancer effect and induced apoptosis in HeLa cell lines both in vitro and in vivo.     

The effect of isolancifolide on the apoptosis in HL-60 cells through caspase-8-dependent and -independent pathways

Isolancifolide is a compound extracted and isolated from Actinodaphne lancifolia, which is a traditional oriental medicine. To determine whether isolancifolide has therapeutic potential as an anticancer molecule, we assessed its apoptotic effects on HL-60 cells, a human leukemia cell line. Apoptotic activities were investigated using DNA fragmentation assay, immunoblotting, and flow cytometry. We found that the inhibitory concentration 50% of isolancifolide was approximately 20 M. The time- and dose-dependent effects of isolancifolide on apoptosis were determined by DNA fragmentation and propidium iodide staining, and the involvement of caspases and the Bcl-2 family in isolancifolide-induced apoptosis was assessed by Western blotting. During exposure to isolancifolide, the pro-forms or full length of caspases-8, -3, and Bid were decreased, as assessed by Western blotting, while the levels of cleaved forms of caspases-8, -3, and PARP were increased. We observed that the release of cytochrome c and Smac/DIABLO from the mitochondria to the cytosol was accompanied by the loss of mitochondrial membrane potential. The caspase specific inhibitors, z-IETD-fmk and z-LEHD-fmk, blocked the accumulation of sub-G1 cells and the release of cytochrome c, but not that of Smac/DIABLO. These results indicate that isolancifolide induces apoptosis of HL-60 cells through both death receptor and mitochondria pathways, in caspase-8-dependent and -independent manners, suggesting that isolancifolide may be useful in anticancer strategies.     

Induction of apoptosis by lovastatin through activation of caspase-3 and DNase II in leukaemia HL-60 cells

Lovastatin, an HMG-CoA reductase inhibitor, was found to suppress growth and induce apoptosis in culture human promyelocytic leukaemic cell, HL-60. However, the mechanisms of lovastatin-induced apoptosis are still unclear. In this study, we attempted to elucidate the signal transduction pathway for lovastatin-induced apoptosis in HL-60 cells in a dose- and time-dependent manner. The features of this apoptosis were attenuated by the presence of mevalonate, a metabolic intermediate of cholesterol synthesis. Treatment of lovastatin caused a rapid release of mitochondrial cytochrome c into cytosol and subsequent induction of caspase-3, but not caspase-1 activity. Lovastatin also stimulated proteolytic cleavage of poly-(ADP-ribose) polymerase (PARP), and followed by the appearance of caspase activity and DNA fragmentation. Pretreatment with caspase-3 inhibitors, Ac-DEVD-CHO and Z-VAD-FMK, inhibited lovastatin induced caspase-3 activity and DNA fragmentation. Furthermore, we demonstrated that DNase II was involved in the DNA fragmentation induced by lovastatin. These results suggested that the mechanism of lovastatin induced HL-60 cells apoptosis through activation of caspase-3 and DNase II activities.     

c-FLIP knockdown induces ligand-independent DR5-, FADD-, caspase-8-, and caspase-9-dependent apoptosis in breast cancer cells

Cellular-FLICE inhibitory protein (c-FLIP) is an inhibitor of apoptosis downstream of the death receptors Fas, DR4, and DR5, and is expressed as long (c-FLIP_L) and short (c-FLIP_S) splice forms. We found that the knockdown of c-FLIP using small interfering RNA (siRNA) triggered ligand-independent caspase-8- and -9-dependent spontaneous apoptosis and decreased the proliferation of MCF-7 breast cancer cells. Further analysis revealed that an apoptotic inhibitory complex (AIC) comprised of DR5, FADD, caspase-8, and c-FLIP_L exists in MCF-7 cells, and the absence of c-FLIP_L from this complex induces DR5- and FADD-mediated caspase-8 activation in the death inducing signaling complex (DISC). c-FLIP_S was not detected in the AIC, and using splice form-specific siRNAs we showed that c-FLIP_L but not c-FLIP_S is required to prevent spontaneous death signaling in MCF-7 cells. These results clearly show that c-FLIP_L prevents ligand-independent death signaling and provides direct support for studying c-FLIP as a relevant therapeutic target for breast cancers.     

c-FLIP knockdown induces ligand-independent DR5-, FADD-, caspase-8-, and caspase-9-dependent apoptosis in breast cancer cells

Cellular-FLICE inhibitory protein (c-FLIP) is an inhibitor of apoptosis downstream of the death receptors Fas, DR4, and DR5, and is expressed as long (c-FLIP(L)) and short (c-FLIP(S)) splice forms. We found that the knockdown of c-FLIP using small interfering RNA (siRNA) triggered ligand-independent caspase-8- and -9-dependent spontaneous apoptosis and decreased the proliferation of MCF-7 breast cancer cells. Further analysis revealed that an apoptotic inhibitory complex (AIC) comprised of DR5, FADD, caspase-8, and c-FLIP(L) exists in MCF-7 cells, and the absence of c-FLIP(L) from this complex induces DR5- and FADD-mediated caspase-8 activation in the death inducing signaling complex (DISC). c-FLIP(S) was not detected in the AIC, and using splice form-specific siRNAs we showed that c-FLIP(L) but not c-FLIP(S) is required to prevent spontaneous death signaling in MCF-7 cells. These results clearly show that c-FLIP(L) prevents ligand-independent death signaling and provides direct support for studying c-FLIP as a relevant therapeutic target for breast cancers.     

Microtubule damaging agents induce apoptosis in HL 60 cells and G2/M cell cycle arrest in HT 29 cells

Microtubule damaging agents (such as paclitaxel and nocodazole (ND)) have been used in the clinical cancer chemotherapy. However, the molecular mechanisms of these agents in the induction of anti-cancer activity are still unclear. In the present study, we demonstrated that 0.2 microM podophyllotoxin (PDP) induced the occurrence of apoptosis in human leukemic (HL 60) cells and cell cycle arrest at the G2/M phase in HT 29 cells. Our results suggest that the PDP-induced G2/M arrest in HT 29 cells was through the intracellular events including (a) inhibition of normal mitotic spindle formation, (b) elevation of cyclin B1/cdc2 kinase activity, (c) concomitant increases in cdc 25 A phosphatase and cdk 7 kinase activity, and (d) down-regulation of the wee-1 protein expression. On the other hand, activations of the caspases 3, 8, and 9, Bcl-2 hyper-phosphorylation, and increased leakage of cytochrome c from mitochondria into cytosolic fraction were detected in the PDP-treated HL 60 cells. These listed intracellular events were interpreted to lead to the apoptosis observed in PDP-treated HL 60 cells. We further demonstrated that activation of c-jun N-terminal kinase (JNK) signaling pathway may play an important role in the PDP-induced Bcl-2 phosphorylation and apoptosis in HL 60 cells as evidenced by the JNK specific anti-sense oligonucleotide experiment. Our results demonstrated that the occurrence of apoptosis or G2/M cell cycle arrest induced by microtubule damaging agents in different cancer cells was through independent mechanisms. The results from the present study highlight the molecular mechanisms underlying of the PDP-induced anti-cancer activity.     

N,N-dimethyl phytosphingosine induces caspase-8-dependent cytochrome c release and apoptosis through ROS generation in human leukemia cells

N,N-dimethyl phytosphingosine (DMPS) blocks the conversion of sphingosine to sphingosine-1-phosphate (S1P) by the enzyme sphingosine kinase (SK). In this study, we elucidated the apoptotic mechanisms of DMPS action on a human leukemia cell line using functional pharmacologic and genetic approaches. First, we demonstrated that DMPS-induced apoptosis is evidenced by nuclear morphological change, distinct internucleosomal DNA fragmentation, and an increased sub-G1 cell population. DMPS treatment led to the activation of caspase-9 and caspase-3, accompanied by the cleavage of poly(ADP-ribose) polymerase (PARP) and led to cytochrome c release, depolarization of the mitochondrial membrane potential, and downregulation of the anti-apoptotic members of the bcl-2 family. Ectopic expression of bcl-2 and bcl-xL conferred resistance of HL-60 cells to DMPS-induced cell death, suggesting that DMPS-induced apoptosis occurs predominantly through the activation of the intrinsic mitochondrial pathway. We also observed that DMPS activated the caspase-8–Bid–Bax pathway and that the inhibition of caspase-8 by z-IETD-fmk or small interfering RNA suppressed the cleavage of Bid, cytochrome c release, caspase-3 activation, and apoptotic cell death. In addition, cells subjected to DMPS exhibited significantly increased reactive oxygen species (ROS) generation, and ROS scavengers, such as quercetin and Tiron, but not N-acetylcysteine (NAC), inhibited DMPS-induced activations of caspase-8, -3 and subsequent apoptotic cell death, indicating the role of ROS in caspase-8-mediated apoptosis. Taken together, these results indicate that caspase-8 acts upstream of caspase-3, and that the caspase-8-mediated mitochondrial pathway is important in DMPS-induced apoptosis. Our results also suggest that ROS are critical regulators of caspase-8-mediated apoptosis in DMPS-treated leukemia cells.     

Effects of chemically modified tetracyclines (CMTs) in sensitive, multidrug resistant and apoptosis resistant leukaemia cell lines

Recently discovered chemically modified tetracyclines (CMTs) have shown in vitro and in vivo anti-proliferative and anti-tumour activities. Here, we evaluated in vitro the anti-proliferative and apoptotic activity of six different dedimethylamino chemically modified tetracyclines (CMT-1, CMT-3, CMT-5, CMT-6, CMT-7 and CMT-8) in sensitive and multidrug resistant myeloid leukaemia cells (HL60 and HL60R) in vitro. Three of these compounds (CMT-5, CMT-6, CMT-7) showed low cytotoxic activity both in sensitive and in resistant cells, CMT-3 was endowed with a high anti-proliferative activity only in sensitive cells and was moderately effective as apoptosis inducing agent, with an activity similar to that shown by doxycycline. On the contrary, CMT-1 and CMT-8 were very effective as programmed cell death inducing agents. The apoptotic pathway activated by these compounds involved the activation of caspases, especially caspase-9 and, for CMT-1, also the activation of FAS: Interestingly CMT-8, but not CMT-1, was able to induce apoptosis in multidrug resistant HL60R and in Fas-ligand resistant HUT78B1 cell lines. These properties, together with others previously described (e.g. anti-metastatic and anti-osteolytic activities), suggest that CMT-8 may have important applications in the clinical management of cancer. The comparative analysis of structure-activity relationship of CMT-8 and doxycycline suggests that the C-5 hydroxy moiety may play an important role in conferring activity in multidrug resistant cells. These findings appear to support the hypothesis that CMT-8 may represent an interesting lead for the development of a new class of potent apoptosis inducer agents active in multidrug resistant and Fas-ligand resistant malignancies.     

Anthrapyridones, a novel group of antitumour non-cross resistant anthraquinone analogues. Synthesis and molecular basis of the cytotoxic activity towards K562/DOX cells

1. Multidrug resistance (MDR) to antitumour agents, structurally dissimilar and having different intracellular targets, is the major problem in cancer therapy. MDR phenomenon is associated with the presence of membrane proteins which belong to the ATP-binding cassette family transporters responsible for the active drug efflux leading to the decreased intracellular accumulation. 2. The search of new compounds able to overcome MDR is of prime importance. 3. Recently we have synthesized a new family of anthrapyridone compounds. The series contained derivatives modified with appropriate hydrophobic or hydrophylic substituents at the side chain. 4. The interaction of these derivatives with erythroleukemia K562 sensitive and K562/DOX resistant (overexpressing P-glycoprotein) cell lines has been examined. The study was performed using a spectrofluorometric method which allows to continuously follow the uptake and efflux of fluorescent molecules by living cells. 5. It was demonstrated that the increase in the lipophilicity of anthrapyridones favoured the very fast cellular uptake exceeding the rate of P-gp dependent efflux out of the cell. For these derivatives, very high accumulation (the same for sensitive and resistant cells) was observed and the in vitro biological data confirmed that these compounds exhibited comparable cytotoxic activity towards sensitive and P-gp resistant cell line. In contrast, anthrapyridones modified with hydrophylic substituents exhibited relatively low kinetics of cellular uptake. 6. For these derivatives decreased accumulation in resistant cells was observed and the in vitro biological data demonstrated that they were much less active against P-gp resistant cells in comparison to sensitive cells. 7.We also studied, using confocal microscopy, the intracellular distribution of anthrapyridones in NIH-3T3 cells. Our data showed that these compounds were strongly accumulated in the nucleus and lysosomes.     

8-硝基白杨素诱导HL-60细胞凋亡和抑制增殖与PTEN-Akt途径的相关性研究

目的 观察8-硝基白杨素(NOChR)抑制人急性髓性白血病细胞系(HL-60)细胞增殖和诱导凋亡的作用,并探讨其作用机制.方法 体外培养HL-60细胞;MTT比色法检测增殖活性;流式细胞术定量分析细胞凋亡程度;琼脂糖凝胶电泳观察DNA梯形条带.Western Blot分析HL-60细胞PTEN、P-Akt蛋白表达的影响.结果 NOChR可显著抑制HL-60细胞增殖,呈浓度依赖性,IC50为1.34 μmol;NOChR具有诱导HL-60细胞凋亡的作用,且呈浓度和时间依赖性.NOChR以浓度和时间依赖方式上调HL-60细胞PTEN蛋白的表达和抑制P-Akt蛋白的表达,其作用可被PPARγ特异性阻断剂GW9662(10μmol)预孵育拮抗.结论 NOChR诱导HL-60细胞凋亡作用与其活化PPARγ、上调PTEN蛋白表达、抑制Akt磷酸化相关.     

2 (±)-7, 8, 3′, 4′, 5′-Pentamethoxyflavan induces G2/M phase arrest and apoptosis in human leukemia HL60 cells

Objective Flavans are a set of naturally occurring flavonoids possessing a 2-phenylchroman nucleus, which are widely distributed in the plant kingdom. A number of flavan compounds exhibit antitumor activities. In our previous report, a straightforward synthetic procedure for 2 (±)-7, 8, 3′, 4′, 5′-pentamethoxyflavan (PMF) was developed. To be more important, PMF showed growth inhibitory effect on various human tumor cell lines, especially against HL60 ceils. In the present study, we aim to investigate the molecular mechanisms of action of PMF in HL60 cells. This is the first report of the molecular mechanisms on anti-tumor effect of flavan compounds. Methods Trypan blue exclusion experiment was used for cell growth inhibition assay. Cell apoptosis, cell cycle distribution and the mitochondrial membrane potential (MMP) were assessed by flowcytometric analysis after AO/EB, PI and Rh123 flurescence staining, respectively. Cell cycle- and apoptosis-related proteins were detected using western blotting analysis. Results PMF (1-30 μM) inhibited the growth of HL60 cells in a time- and concentration-dependent manner. Antiproliferative effect of PMF on HL60 cells was associated with G2/M cell cycle arrest, which was mediated by regulating the expression of p21, Cdc25C and cyclin A proteins and inhibiting the phosphorylation of Cdc2 at Thr161. The prolonged PMF treatment also induced apoptosis of HL60 cells, which was characterized by DNA fragmentation, cleavage of poly (ADP-ribose) polymerase, easpase-3, caspase-8 and caspase-9, changes of Bcl-2 and Bax expression and a decrease in the mitochondrial membrane potential (MMP). Furthermore, caspase-3 inhibitor, not caspase-8 inhibitor and caspase-9 inhibitor, completely blocked PMF-caused apoptosis. Conclusions PMF inhibited the growth of HL60 cells via induction of G2/M arrest and apoptosis. Blockade of cell cycle was associated with the downregulation of Cdc2 complex activity. Both death receptor and mitochondrial apoptotie pathways explained PMF-eaused apoptosis.     

右美托咪定对感染性休克大鼠脾脏及胸腺caspase-3、caspase-8、caspase-9表达及淋巴细胞凋亡的影响

目的研究右美托咪定对内毒素诱导感染性休克大鼠细胞免疫的作用。方法选取12周龄雄性Walse大鼠18只,采用数字表法随机分为空白组(S组)、内毒素组(E组)和右美托咪定治疗组(D组),每组6只。S组静脉推注1.0 mL/kg 0.9%生理盐水后,持续泵入同浓度的生理盐水,E组、D组均采用静脉注射内毒素(LPS)建立感染性休克大鼠模型,D组在注射内毒素后持续微泵右美托咪定。持续监测心率(HR)、呼吸、有创动脉血压(ABP)及平均动脉压(MAP),用药后0.5、1、2、3、4、6 h检测血清中IL-4(白介素-4)、IL-10、IFN-γ(γ干扰素)和IL-2的浓度,6 h后处死大鼠,检测大鼠脾脏及胸腺caspase-3、caspase-8、caspase-9活性,测定淋巴细胞凋亡情况及Th1/Th2。结果①与S组相比,E组、D组大鼠血清的抗炎因子IL-4、IL-10和促炎因子IFN-γ、IL-2均显著提高,其差异均有统计学意义(P<0.05)。随着治疗时间延长,E组的IL-4、IL-10水平降低,IFN-γ、IL-2水平升高;D组IL-4、IL-10水平升高,IFN-γ、IL-2水平降低;两组比较差异有统计学意义(P<0.05)。②与E组相比,D组大鼠脾脏及胸腺caspase-3、caspase-8、caspase-9表达及淋巴细胞凋亡的阳性细胞数均显著减少,差异有统计学意义(P<0.05)。③D组大鼠脾脏及胸腺Th1/Th2比率均显著高于E组,差异有统计学意义(P<0.05)。结论右美托咪定对感染性休克大鼠具有减轻炎症反应和改善免疫功能的作用,有利于改善预后。     

Role of structural factors of antitumour anthraquinone derivatives and analogues in the ability to undergo bioreductive activation by NADPH cytochrome P450 reductase: implications for increasing the activity against sensitive and multidrug-resistant leukaemia HL60 cells

The aim of this study was to examine the role of structural factors of antitumour anthraquinone derivatives and analogues in the ability to undergo bioreductive activation by NADPH cytochrome P450 reductase (CPR) and determine the impact of this activation on increasing the activity especially with regard to multidrug resistant (MDR) tumour cells. It was found that at a high NADPH concentration (500 μmol/l), the anthracenedione agent ametantrone, with an unmodified quinone structure, was susceptible to CPR-dependent reductive activation. In contrast, it was shown that compounds with modified quinone grouping (benzoperimidine BP1, anthrapyridone CO1 and pyrazolopyrimidoacridine PPAC2) did not undergo reductive activation by CPR. This suggests that the presence of a modified quinone function is the structural factor excluding reductive activation of antitumour anthraquinone derivatives and analogues by CPR. In the second part of the work, the ability of antitumour anthraquinone derivatives and analogues to inhibit the growth of the human promyelocytic, sensitive leukaemia HL60 cell line as well as its MDR sublines exhibiting two different phenotypes of MDR related to the overexpression of P-glycoprotein (HL60/VINC) or MRP1 (HL60/DOX) was studied in the presence of exogenously added CPR. A significant increase in the activity of ametantrone with an unmodified quinone structure after its reductive conversion by CPR was observed against HL60 as well as HL60/VINC and HL60/DOX cells, whereas in the case of quinone-modified compounds (BP1, CO1 and PPAC2), the presence of the activation system had no effect on their activity against the sensitive and MDR tumour cells examined.