多种化疗药对凋亡抑制蛋白Survivin在HL-60细胞中表达影响的研究

Objective： To explore the relationship between survivin and drug resistance, and the changes of the survivin expression in HL-60 cells treated with three kinds of chemotherapeutic drugs. Methods： HL- 60 cells were treated with appropriate concentration of daunomycin （DNR）, mitoxantrone （MIT） or arsenic trioxide （As2O3）. The expression of survivin mRNA and protein on the first or third day was detected by RT-PCR and Western blot respectively. Results： The expression of survivin mRNA was decreased on the first day by 10% in DNR-treated group, 40% in MIT-treated group （P〈0.01） and 25% in As2O3-treated group （P〈0.01） respectively. On the third day, the expression of survivin mRNA in DNR- and MIT-treated group was up-regulated to 120% （P〈0.05） and 165% （P〈0.01） respectively as compared with that on the first day, but down-regulated to 68% in As2O3-treated group （P〈0.01）. As compared with control group, the expression of survivin protein in DNR- or MIT-treated group was increased by 14% or 11% on the third day respectively, but it was decreased by 18% in As2O3-treated group. Conclusion： In DNR- and MIT-treated group, the expression of surivin was decreased at first and then increased obviously, which may be one of the causes for resistance to chemotherapy against leukemia. Different from other two drugs, As2O3 may play an important role in restoring chemotherapy sensitivity.     

Expression of memory to the terminal differentiation inducing activity of tiazofurin in HL-60 leukemia cells

Tiazofurin, a potent inhibitor of inosine 5'-phosphate dehydrogenase, depletes guanine nucleotide pools and induces granulocytic maturation of HL-60 leukemia cells. These effects are reversed when cells exposed to this agent for 24 h are washed and placed in tiazofurin-free medium. HL-60 cells treated with tiazofurin for a 24 h period, retain a precommitment memory that lessens the time interval necessary for cells to express the mature phenotype upon re-exposure. That protein synthesis was required for maintaining the expression of memory was demonstrated by the finding that memory was blocked when primed cells were exposed to cycloheximide during the intervening inducer-free interval, but not during the priming or subsequent drug exposure periods. The findings have significance with respect to the sequence of events required for commitment to a differentiation pathway.     

Characterization of differentiation-inducer-resistant HL-60 cells

Sub-lines of the cultured human promyelocytic leukemia cell line HL-60 were individually selected for their ability to sustain exponential growth in the presence of 3 structurally-unrelated inducers of granulocytic differentiation - retinoic acid (RA), dimethylsulfoxide (DMSO), and 6-thioguanine (6TG). Selections were made by step-wise augmentation to final drug concentrations of 10(-3)mM RA, 169mM (1.2%) DMSO and 0.12mM (20 micrograms ml-1) 6TG. In addition to growth resistance, cells in each sub-line displayed variable cytodifferentiation resistance to each of the 3 selective agents, which was quantitated as the ratio of the concentration of drug required to induce differentiation in 50% of the cells in each resistant sub-line versus comparably-passaged wild-type HL-60 cells. The levels of resistance/cross-resistance were as follows: RA-resistant (res) sub-line greater than 2700-fold to RA, 1.3-fold to DMSO and greater than 1.5-fold to hypoxanthine (HXN; the noncytotoxic purine base inducer analogue of 6TG); DMSO-res sub-line 2.5-fold to DMSO, 137-fold to RA and greater than 1.5-fold to HXN; and 6TG-res sub-line greater than 1.5-fold to HXN, 9-fold to RA and 1.6-fold to DMSO. These sub-lines were not cross-resistant to sodium butyrate (NaBut), a monocyte inducer, or to 12-0-tetradecanoylphorbol 13-acetate (TPA), a macrophage inducer. HL-60 sub-lines selected by exposure to a single high concentration of 5-bromo-2'-deoxyuridine (BUdR; 3.3 X 10(-2)mM) or oubain (Ou; 5 X 10(-3)mM) were not or were slightly cross-resistant to either granulocyte or monocyte inducers. Although some variations in line/sub-line phenotype were observed, this was minor compared to the quantitative variations in response to individual inducing agents. The RA-res and 6TG-res sub-lines contained numerous double minute chromosomes (indicators of amplified genes) which were either absent or present in much smaller numbers in the parental wild-type cells or in the other drug-resistant sub-lines. There was little change or a decrease in the amplification level of the known amplified oncogene c-myc in the various drug-resistant sub-lines compared to wild-type HL-60 cells. These results (a) confirm that the neutrophilic granulocytic and monocytic/macrophagic differentiation programs in HL-60 cells are mechanistically different and separable; (b) suggest that both agent-specific and common quantitative alterations contribute to the mechanism(s) for resistance to granulocyte differentiation; and (c) suggest that the latter quantitative defects could be related to amplification of genes other than c-myc.     

Expression of selected genes and oncogenes in differentiated HL-60 cells and primary cells from human leukemias

cDNA clones complementary to mRNA of cells from patients with chronic lymphocytic leukemia (CLL) were used to examine quantitative changes in the mRNA levels of specific genes in human leukemia leukocytes. Twenty one CLL-positive clones that did not hybridize with placental mRNA were studied. These clones were significantly represented in the mRNA from leukemic leukocytes and were not represent in the mRNA from normal leukocytes. There was high level of expression of 7-2D gene in CLL and B lymphoma cells. RNA hybridizing with clone 7-3G was comparatively highly abundant in CCRF-CEM and EB virus transformed lymphoid cell, while clone 6-1E was highly represented in the mRNAs of Molt 3 and CCRF-CEM cells. The expression of three clones (6-1E, 7-3G and 9-5C) selected from a CLL cDNA library was studied by nucleic acid hybridization in human promyelocytic leukemia cell (HL-60) treated with chemical inducers of cell differentiation. The differentiation of HL-60 cells into macrophage-like cells upon induction by 12-o-tetradecanoylphorbol-13-acetate (TPA) was accompanied by rapid induction of the expression of 6-1E and 7-3G genes. The levels of expression of the 9-5C gene were not altered during macrophage-monocytic or granulocytic differentiation of HL-60 cells. The expression of the 6-1E and/or 7-3G gene was induced by TPA in four of 6 samples derived from patients who achieved complete remission, but not in any of the acute nonlymphocytic leukemia samples from patients who failed to achieve complete remission. These findings suggest that expression of the 6-1E and 7-3G genes is related to macrophage-monocytic differentiation and that alterations of these gene expressions in fresh leukemic cells after one hour of TPA treatment are of prognostic significance in predicting the response to treatment. The primary structure of a cDNA of a gene (6-1E) selectively expressed in CLL was determined. A computer search in the nucleotide sequence data bank did not identify this gene as any other gene. The 677 nucleotide mRNA is composed of a 384 nucleotide pol A tail. Moreover, the sequences of the other cDNA clones (1-6G, 5-2C,5-5G, 6-1G, 7-3G, 7-4A, 8-6G, and 9-5C) are not present in those of the data base of GenBank recorded up to 1988.(ABSTRACT TRUNCATED AT 400 WORDS)     

From molecular characteristics to cellular events in apoptosis-resistant HL-60 cells

The ability to induce apoptosis in tumor cells is critical to elicit a positive response to cytotoxic chemo-therapy. In this study, we investigated the effect of the topoisomerase I inhibitors camptothecin and SN-38, known to cause an unusual form of DNA damage, on apoptotic pathways using the leukemic cell line HL-60 and its vincristine-resistant variant HL-60 VCR. Both camptothecin and SN-38 induced high levels of apoptosis in sensitive cells when compared to the multidrug-resistant ones. Interestingly, a higher BCL-2/BAX ratio was observed in HL-60 VCR at the basal state and during treatments. Moreover, these cells which did not exhibit Bcr-abl translocation or bcrp efflux pump, overexpressed topoisomerase I protein. The data provide evidence that BCL-2 protein could protect HL-60 VCR from mitochondrial membrane depolarization and block ROS production in these cells. Finally, our results suggest that dysregulation of proteins associated with DNA replication and apoptotic process could contribute to the multidrug-resistance phenotype.     

Alterations in histone phosphorylation in HL-60 cells specific to monocytic differentiation

In order to examine the role of histone phosphorylation in regulation of the pathway of HL-60 cell differentiation, cells were labelled with [32P]phosphoric acid and histones fractionated by two-dimensional polyacrylamide gel electrophoresis. The monocytic inducer 12-O-tetradecanoylphorbol-13-acetate (TPA) was found to specifically stimulate phosphorylation of histone H2B in a concentration-dependent manner. At a concentration of 100 mM, H2B phosphorylation was stimulated 2.3-fold after 4 h. A second monocytic inducer 1,25-dihydroxy-cholecalciferol (100 nM) also induced phosphorylation specifically in histone H2B. In contrast, the granulocytic inducers DMSO (1.5%) or retinoic acid (1 microM) did not increase phosphorylation in any histone species.     

c-myc down regulation and precommitment in HL-60 cells due to bromodeoxyuridine

HL-60 human nonlymphocytic leukemia cells undergo terminal differentiation along either the myeloid or monocytic pathway in a process previously shown to involve two sequential steps, early events leading to a precommitment state and late events leading to onset of terminal differentiation. The present report shows that bromodeoxyuridine induces the early events leading to precommitment. In this course bromodeoxyuridine causes the rapid down regulation of the c-myc protooncogene. The course is similar to other common inducers of HL-60 differentiation including retinoic acid, dimethyl sulfoxide, 1,25-dihydroxyvitamin D3, and sodium butyrate. HL-60 cells which were initially exponentially proliferating were exposed to 10 microM bromodeoxyuridine for 24 h, a period corresponding to one division cycle in these cells. When the cells were subsequently exposed to either retinoic acid or 1,25-dihydroxyvitamin D3, onset of G1/0 specific growth arrest and display of the differentiated phenotype occurred within 24 h. This is in contrast to the 48-h exposure needed for onset of terminal differentiation if either inducer is used singly during continuous exposure, as has been reported previously. Thus bromodeoxyuridine consummated the early events, including the rapid down regulation of c-myc message levels, which occur during the first division cycle of the induced cellular metabolic cascade leading to onset of terminal differentiation. The ability of bromodeoxyuridine to drive events in the metabolic cascade leading to onset of terminal differentiation was specific for early events, inasmuch as it was relatively ineffective at driving late events. Down regulation of c-myc was not in itself sufficient to result in subsequent terminal differentiation, since pulse exposure to bromodeoxyuridine followed by culture in inducer free medium resulted in little G1/0 specific growth arrest or phenotypic differentiation. Continuous exposure to bromodeoxyuridine, in contrast, resulted in significant G1/0 specific growth arrest but little phenotypic differentiation, indicating that the regulation of cell cycle transit and differentiation are separable.     

Arsenic trioxide downregulates telomerase activity in HL-60 cells

Telomeres are the specialized nucleoproteincomplexes at the physical ends of eukaryoticchromosomes[1]. Telomere length decreases along with increasing cycles of cell divisions. Telomere shortening has therefore been proposed to play a role in cellular senescence. Telomerase is a protein-RNA enzyme complex that adds a six-base DNA sequence (TTAGGG) to the ends of chromosomes and thereby prevents their shortening. This enzyme is specifically activated in most malignant tumors but is usuall…     

抗bcl-2核酶在HL-60细胞内的表达

设计并合成针对bcl-2 mRNA的“锤头型”(hammerhead)核酶基因,克隆后经测序表明序列正确。bcl-2和RZ基因经体外转录和切割实验后,表现出很强的切割活性,然后把RZ基因定向克隆于真核表达载体pDOR-neo,重组体被命名为pDOR-RZ。通过脂质体(lipofectin)介导的DNA转染法,成功地把pDOR-RZ导入HL-60细胞。用Southern印迹杂交、RNA斑点杂交和流式细胞仪(FCM),观察RZ基因在HL-60细胞内的表达。结果表明:(1)RZ在转染HL-60细胞后72小时得以表达;(2)由于RZ的表达,细胞内Bcl-2蛋白合成受到抑制;(3)在FCM图谱上可见到明显的凋亡峰。     

Adriamycin Sensitizes Adriamycin-Resistant HL-60/ADR Cells to TRAIL-Mediated Apoptosis

OBJECTIVE To study whether an adriamycin-resistant cell line(HL-60/ADR) can be sensitized by adriamycin(ADR) to TRAIL-mediated apoptosis.METHODS The mRNA levels of the TRAIL receptor and apoptosis-related signaling molecules involved in the TRAIL-mediated apoptotic pathway were measured by RT-PCR.The protein levels of apoptotic-related signaling molecules involved in the TRAIL-mediated apoptotic pathway and processed caspase-3,caspase-9,and caspase-8 were measured by Western blots.Apoptosis was assessed by flow cytometry.Mitochondrial membrane potential was analyzed by DiOC6(3) staining.Cytotoxicity was determined by the colorimetric MTT viability/ proliferation assay.RESULTS Treatment with a combination of TRAIL and subtoxic concentrations of ADR resulted in synergistic cytotoxicity and apoptosis for both the parental HL-60 and the HL-60/ADR cells.For HL-60,there was a 5-fold potentiation and synergy in cytotoxicity for TRAIL and for HL-60/ADR,cytotoxicity to TRAIL was potentiated 6-fold with ADR.Adriamycin treatment modestly up-regulated TRAIL-R2(DR5),but had no effect on the expression of Fas-associated death domain,c-FLIP,Bcl-2,Bcl-xL,Bax,and IAP family members(cIAP-1,cIAP-2,XIAP,and survivin).The protein levels of pro-caspase-8 and pro-caspase-3 were not affected by ADR,whereas pro-caspase-9 and Apaf-1 were up-regulated.Combined treatment with TRAIL and ADR resulted in activation of caspase-9 and caspase-3,but there was no detectable processing of caspase-8 beyond the background levels.There was signif icant depolarization of the mitochondrial membrane by the combined treatment of both cell lines and it was more pronounced in the parental HL-60 cell line.The combined treatment with TRAIL and ADR resulted in 42.6% of the HL-60/ADR cells undergoing DNA fragmentation,whereas treatment with either ADR or TRAIL alone resulted in 5.46% and 21.3% DNA fragmented cells,respectively.Similar results were obtained with the HL-60 cells.CONCLUSION These fi ndings demonstrate that ADR can still signal ADR-resistant tumor cells,resulting in the modifi cation of the TRAIL-mediated signaling pathway and apoptosis.     

Relationship of c-myc expression to differentiation and proliferation of HL-60 cells

We have compared changes in c-myc expression in HL-60 promyelocytic leukemia cells induced to differentiate by dimethyl sulfoxide or growth inhibited in an undifferentiated state. Under these conditions, c-myc expression did not correlate with the proportion of proliferating cells. The kinetics of the decrease in c-myc expression upon differentiation induction is paralleled closely by an increasing proportion of histochemically detected differentiated myeloid cells and by a decrease in clonogenic potential but not by changes in the proportion of proliferating cells. Changes in c-myc expression subsequent to differentiation induction can therefore be directly related to the differentiation process rather than to a cell cycle-related phenomenon.     

雷公藤多甙诱导HL-60细胞凋亡

目的：探讨雷公藤多甙对ＨＬ－６０细胞凋亡的作用。方法：应用细胞形态学检查,ＤＮＡ凝胶电泳及流式细胞仪分析检测。结果：ＨＬ－６０细胞加上雷公藤多甙１０ｍｇ／Ｌ孵育７２ｈ,流式细胞仪检测细胞凋亡率为２９．４％（与空白对照组比较,Ｐ〈０．０１）。电检查和光镜检查均可见细胞核固缩、碎裂等。ＤＮＡ电泳显示明显的梯状条带。结论：雷公藤多甙能诱导ＨＬ－６０细胞凋亡,提示雷公藤多甙可能具有抗白血病作用。     

siRNA-2提高HL-60细胞对高三尖杉酯碱敏感性的实验研究

 目的 研究以bcl-2基因为靶标的有效siRNA对HL-60细胞高三尖杉酯碱（HT）药物敏感性的影响。方法 通过脂质体将siRNA转入HL-60细胞株并与HT联合培养，于24，48，72 h，用MTT法检测对细胞生长的抑制，用流式细胞仪检测HL-60细胞bcl-2蛋白的表达率，细胞内活性氧（ROS）水平变化及细胞线粒体膜电位的变化。结果 siRNA明显提高HT对HL-60细胞的生长抑制效应；抑制细胞bcl-2蛋白的表达，提高细胞内ROS水平，降低线粒体膜电位（P＜0.05）。结论 以bcl-2基因为靶标的siRNA能提高白血病细胞HL-60对HT敏感性。     

HL-60及其耐药细胞之间线粒体膜及线粒体中Bid差异研究

目的研究线粒体膜及线粒体中Bid参与肿瘤耐药的机制.方法采用紫外分光光度仪和流式细胞仪检测Ca2 诱导下HL-60及其耐药细胞HL-60/E6线粒体膜通透改变孔道开放和线粒体膜电位的变化,Western blot检测线粒体中Bid表达.结果Ca2 诱导下HL-60/E6细胞线粒体膜电位下降幅度和膜通透改变孔道开放程度明显低于HL-60细胞.药物AMD作用后线粒体中Bid表达呈时间依赖性,而且在不同时间,HL-60/E6细胞线粒体中Bid表达均明显低于HL-60细胞.结论HL-60/E6细胞耐药与Ca2 诱导下线粒体膜电位下降幅度及膜通透改变孔道开放程度的降低有关,还与线粒体上Bid表达降低有关.     

黄芩苷作用HL-60细胞前后c-myc基因表达的变化

 目的 研究中药黄芩苷（baicalin）对人髓系白血病细胞株HL-60细胞增生、凋亡的影响及探讨c-myc基因在其中的作用。方法 培养人髓系白血病细胞株HL-60细胞,应用MTT法绘制细胞生长曲线观察黄芩苷对HL-60细胞增生的影响;DNA凝胶电泳观察细胞凋亡;RT-PCR检测黄芩苷作用前后c-myc基因mRNA表达水平的变化;Western blot检测黄芩苷作用前后c-myc蛋白表达水平的变化。结果　细胞生长曲线结果示黄芩苷能明显抑制HL-60细胞增生,半数抑制浓度（IC50）约为20μmol／L,DNA 片段化的检出表明黄芩苷能有效诱导HL-60细胞凋亡;黄芩苷作用后HL-60细胞c-myc基因和蛋白的表达水平均下降,并且随作用时间延长,表达下降更明显。结论 黄芩苷能有效抑制HL-60细胞增生,诱导其凋亡,c-myc基因可能参与了黄芩苷抑制HL-60细胞增生和诱导凋亡的过程。     

siRNA对HL-60细胞c-myc蛋白表达的影响

 目的　研究小干扰RNA（siRNA）对白血病细胞c-myc蛋白表达的影响,探寻白血病基因治疗的新方法。方法　应用针对c-myc的siRNA转染HL-60细胞,分别收集转染后24、48和72 h细胞及对照组细胞,提取细胞总蛋白,用Western blotting方法检测c-myc蛋白的表达情况。结果　与对照组相比,转染c-myc siRNA后,细胞c-myc蛋白表达水平明显下降,且c-myc蛋白含量随作用时间的延长而逐渐降低,转染24 h后c-myc 蛋白含量下降约42 %,48 h下降66 %,72 h下降78 %;单因素方差分析显示与对照组相比,差异均有统计学意义（P < 0.05）。结论　c-myc siRNA能降低HL-60细胞c-myc蛋白的表达,其作用具有序列特异性和时间依赖性,有望成为白血病靶向基因治疗的新工具。     

千金子甾醇诱导HL-60细胞凋亡机制研究

目的探讨Bcl-2/Bax信号通路在千金子甾醇诱导HL-60白血病细胞发生凋亡中的作用及其分子机制研究。方法HL-60细胞培养体系中分别加入大、中、小剂量千金子甾醇溶液,甾醇溶液作用细胞24h后,采用CCK-8法检测千金子甾醇对HL-60细胞增殖的抑制作用,光镜下观察细胞形态学变化,AnnexinⅤ/PI流式细胞术检测细胞凋亡,RT-PCR法检测Bcl-2/Bax、Caspase-9和Caspase-3mRNA转录水平,ELISA法检测Caspase-9和Caspase-3蛋白活性。结果 CCK-8法检测结果显示,与对照组比较,千金子甾醇能明显抑制HL-60细胞增殖（F=42.97,P〈0.001）,各个浓度之间进行比较,差异有统计学意义,P〈0.05。流式细胞术检测细胞凋亡率显著增加（F=56.74,P〈0.001）,经10、20和40μg/mL千金子甾醇处理24h后,HL-60细胞早期凋亡率分别为（23.4±3.1）%、（35.7±4.3）%和（53.2±3.9）%,细胞呈典型凋亡形态学改变。千金子甾醇作用后,Bax mRNA转录水平显著升高,Bcl-2mRNA转录水平显著降低,且呈化合物剂量依赖性（F=53.45,P〈0.001）,Caspase-9和Caspase-3 mRNA转录水平升高,且呈化合物剂量依赖性（F=34.21,P〈0.001）,千金子甾醇对HL-60细胞作用24h后Caspase-9和Caspase-3蛋白活性显著升高（F=54.33,P〈0.001）,且随着千金子甾醇浓度增加蛋白活性逐渐升高。结论千金子甾醇通过调节Bcl-2/Bax凋亡信号通路,诱导HL-60细胞凋亡,其作用呈明显剂量依赖性。     

曲古抑菌素A诱导HL-60细胞凋亡机制的研究

目的:探讨曲古抑菌素A(TSA)在体外诱导急性早幼粒白血病HL-60细胞凋亡的机制.方法:采用MTT方法检测TSA对HL-60细胞增殖的影响.流式细胞术检测细胞周期和细胞凋亡,RT-PCR检测凋亡相关基因Bax、Caspase-9和Caspase-3的表达.结果:0.1μmol/L的TSA可明显抑制细胞增殖,P<0.01;0.05 μmol/L的TSA可使细胞周期阻滞在G0/G1期(P<0.05),但0.1 μmol/L的TSA才能引起细胞凋亡(P<0.01);经0.1 μmol/L的TSA作用12 h后,Bax、Caspase-9和Caspase-3基因表达明显升高,P<0.01.结论:TSA诱导HL-60细胞凋亡的机制在于引起细胞周期阻滞,上调Bax、Caspase-9和Caspase-3的表达.     

Se-methylselenocysteine induces apoptosis through caspase activation in HL-60 cells

Apoptosis, a programmed process of cell suicide, has been proposed as the most plausible mechanism for the chemopreventive activities of selenocompounds. In our study, we found that Se-methylselenocysteine (MSC) induced apoptosis through caspase activation in human promyelocytic leukemia (HL-60) cells. Measurements of cytotoxicity, DNA fragmentation and apoptotic morphology revealed that MSC was more efficient at inducing apoptosis than selenite, but was less toxic. Moreover, MSC increased both the apoptotic cleavage of poly(ADP-ribose) polymerase (PARP) and caspase-3 activity, whereas selenite did not. We next examined whether caspases and serine proteases are required for the apoptotic induction by MSC. A general caspase inhibitor, z-VAD-fmk, dramatically decreased cytotoxicity in MSC-treated HL-60 cells and several other apoptotic features, such as, caspase-3 activation, the apoptotic DNA ladder, TUNEL-positive staining and the DNA double-strand break. Interestingly, a general serine protease inhibitor, AAPV-cmk, also effectively inhibited MSC-mediated cytotoxicity and apoptosis. These results demonstrate that MSC is a selenocompound that efficiently induces apoptosis in leukemia cells and that proteolytic machinery, in particular caspase-3, is necessary for MSC-induced apoptosis. On the other hand, selenite-induced cell death could be derived from necrosis rather than apoptosis, since selenite did not significantly induce several apoptotic phenomena, including the activation of caspase-3.