三氧化二砷诱导肝癌HepG2细胞凋亡作用

目的 探讨三氧化二砷（As2O3）诱导肝癌HepG2细胞凋亡作用。方法 应用普通光学显微镜、荧光显向镜和流式细胞仪观察As2O3对HepG2细胞株的形态学改变和诱发凋亡率。结果 As2O3作用于细胞后,可看到较典型的细胞凋亡形态学改变,细胞体积缩小,染色质固综合成斑块状,呈半月型紧贴于核膜周边,核碎裂,凋亡小体形成等,AO/EB荧光染色法显示。细胞凋亡率为4.3%-9.1%.As2O3诱导HepG2细胞凋亡作用呈时间依赖性,最佳浓度为2umol/L。流式细胞仪DNA直方图上呈现典型的亚二倍体凋亡峰。As2O3主要作用于细胞周期的G2/M期。结论 As2O3具有诱导HepG2细胞凋亡作用,存在治疗肝癌的潜在价值。     

三氧化二砷抑制人肝癌细胞株增殖和诱导凋亡作用

目的体外培养人肝癌细胞株HepG-2,BEL-7402,观察测定应用不同浓度三氧化二砷后多种指标的变化,从多个角度探讨三氧化二砷的抗肿瘤作用及其机制.方法应用倒置相差显微镜、电子显微镜、透射电镜、扫描电镜、流式细胞仪、细胞免疫组化法,分别对不同浓度加药组及对照组HepG-2,BEL-7402细胞的存活,形态学改变,细胞DNA含量的分布以及Bc1-2,Bax蛋白的表达进行了观察和测定.结果0.5,1,2μmol/L As2O3均能抑制人肝癌细胞株细胞的生长增殖.流式细胞仪分析显示,加药组在G1期细胞前均出现亚二倍体峰,且G0/G1期细胞减少,S期细胞增多,电镜下,对照组细胞核质比大、核大、核膜有明显切迹,0.5μmol/L As2O3组细胞核质比减小、核变圆、胞质内出现分化良好的细胞器,0.5,1,2μmol/L As2O3组均可见细胞膜完整、核固缩、凋亡小体形成.细胞免疫组化法测定Bcl-2,Bax蛋白的表达以及两者之间的比率均有变化.结论三氧化二砷不仅抑制人肝癌细胞增殖,而且诱导细胞凋亡.诱导肝癌细胞凋亡与Bd-2,Bax蛋白的表达改变有关.     

应用RNA干扰抑制端粒酶逆转录酶表达诱导HepG2细胞凋亡

人端粒酶由RNA亚单位（hTR）和蛋白组分构成。蛋白组分包括端粒酶逆转录酶催化亚基（hTERT）和端粒酶相关蛋白1（hTEPl）。hTERT表达与端粒酶活性密切相关，是细胞永生化过程中端粒酶活化的限速步骤。抑制hTERT的表达可快速诱导细胞凋亡，其机制不是通过端粒缩短所致。表明hTERT除了其蛋白催化活性外，尚可与其他分子相互作用诱导细胞凋亡。     

三氧化二砷诱导人肝癌SMMC-7721细胞凋亡及对OPN表达的影响

目的探讨三氧化二砷（As2O3）治疗肝癌的可行性及机制。方法将一定浓度梯度的As2O3与人肝癌细胞株SMMC-7721孵育后,采用MTT法、荧光显微镜及流式细胞仪检测细胞增殖与凋亡变化,逆转录聚合酶链反应（RT-PCR）检测肝癌细胞株中骨桥蛋白基因（OPN mRNA）表达水平。结果As2O3作用后SMMC-7721细胞生长明显受抑,且呈时间-浓度依赖性;荧光显微镜下细胞呈典型的凋亡形态学改变;在流式细胞仪上可见“凋亡峰”,细胞周期阻滞于G2／M期;细胞OPN mRNA表达阳性,OPN mRNA表达水平明显下调。结论As2O3体外能有效抑制肝癌细胞株生长;其机制可能为诱导细胞凋亡、下调OPN mRNA表达。     

JNK/SAPK信号转导系统在三氧化二砷诱导肝癌细胞凋亡中的作用

目的:探讨JNK/SAPK信号转导系统在三氧化二砷(As2O3)诱导人肝癌细胞株HepG2凋亡过程中的作用.方法:采用MTT法观察不同浓度的As2O3对人类肝癌细胞株HepG2细胞生长的抑制作用;以流式细胞术观察细胞的凋亡率及生长周期的变化;以Western blot法检测p-MEK4、JNK、P-JNK、Caspase-3及PARP蛋白在As2O3作用下及SP600125阻断JNK信号转导通路情况下的表达.结果:各浓度As2O3均能明显抑制肝癌细胞HepG,增殖,且具有剂量依赖性和时间依赖性;流式细胞术(FCM)分析显示,As2O3能够诱导肝癌细胞HepG2凋亡且具有时间依赖性,细胞滞留于G2/M期(0,24,48,72 h百分率分别为7.22%±1.50%,11.56%±0.73%,33.8%±1.62%,46.02%±0.11%):Western blotting结果显示,As2O3诱导肝癌细胞HepG2凋亡伴随着Caspase-3和PARP的活化;As2O3作用于HepG2细胞10 min后P-MEK4和P-JNK蛋白表达开始增加,20 min达到高峰,30 min开始减少,总JNK蛋白的含量无明显改变,MEK4和JNK的激活早于细胞凋亡;用SP600125预处理HepG2细胞株后,可以明显减少Caspase-3和PARP的活化.结论:As2O3可以体外通过诱导细胞凋亡抑制肝癌细胞株HepG2的增殖,细胞凋亡通过Caspase-3途径实现.JNK信号转导通路参与了As2O3诱导的HepG2凋亡反应,并位于Caspase-3的上游.     

三氧化二砷对人肝癌细胞凋亡作用的研究

1. 资料与方法：人肝癌细胞株HepGZ101,由黑龙江省肿瘤医院提供。三氧化二砷注射液由哈医大附属一院制剂室制备提供,浓度为0.5mol/L。用含20%小牛血清的1640培养液在5% CO2浓度的孵箱中传代培养。当细胞基本长满瓶底时,加入不同浓度的三氧化二砷,并设对照组,分别于加药后５d每天观察细胞凋亡情况。在倒置显微镜下观察细胞于药物作用后的形态变化。加入三氧化二砷后每天每个剂量取３瓶消化、离心、用台盼蓝染色并计数,连续５d,绘制生长曲线并计算增殖抑制率。用流式细胞仪进行ＤＮＡ含量及细胞周期的分析。实验重复３次。2. 结果：…     

三氧化二砷诱导类风湿关节炎滑膜细胞凋亡的作用及机制

目的研究三氧化二砷(ATO)对人类风湿关节炎成纤维样滑膜细胞(HFLS-RA)凋亡的作用及机制。方法将HFLS-RA分为单纯培养基空白对照组和0．5、2、8μ,mol/L ATO实验组．分别观察ATO作用72 h电镜下细胞的病理改变以及TUNEL法检测细胞的凋亡；四唑盐(MTT)法检测ATO对HFLS-RA生长的影响；反转录聚合酶链反应(RT-PCR)方法检测ATO作用24 h对核转录因子(NF)-κB的mRNA表达影响。结果电镜下,ATO可以诱导HFLS-RA的凋亡,TUNEL法检测ATO组凋亡指数呈剂量依赖性增加,与对照组相比,2、8μ,mol/L ATO组凋亡指数明显增加(P＜0．05)；ATO呈现时间和剂量依赖性抑制HFLS-RA生长的作用；RT-PCR法表明ATO组NF-κB的mRNA表达剂量依赖性减少,2μmol/L以上ATO可以明显下调NF-KB的mRNA表达(P＜0．05),结论ATO可以抑制HFLS-RA的生长,并且可能通过抑制NF-KB的mRNA表达促进HFLS-RA的凋亡。     

逆转录病毒载体介导的端粒酶抑制基因促进肝癌细胞凋亡

目的:探讨逆转录病毒载体介导的反义端粒酶抑制基因对肝癌细胞系BEL-7402的凋亡诱导作用.方法:用电穿孔的方法把正、反义端粒酶抑制基因导入包装细胞,包装出完整的病毒,用此病毒感染肝癌细胞系BEL-7402,绘制细胞生长曲线来研究其抗肿瘤疗效.应用MTT、流式细胞术研究细胞凋亡情况.结果:肿瘤细胞感染逆转录病毒后,肿瘤生长受到明显抑制,转染反义hTR病毒组BEL-7402细胞凋亡率显著高于转染正义hTR病毒和生理盐水组(61.32%±2.24%vs23.02%±2.13%,4.11%±1.00%,P<0.01),转染反义hTR与5-FU联用细胞凋亡率更高,为71.71%±2.53%.结论:反义端粒酶抑制基因能明显抑制肿瘤细胞的体外生长,与抗肿瘤药物5-FU有协同作用,联合用药可以增强疗效,具有明显抗肿瘤作用.     

人端粒酶催化亚单位锤头状核酶诱导肝癌细胞凋亡的作用

目的 构建带有U6启动子的人端粒酶催化亚单位锤头状核酶真核表达质粒及其突变体,转染入肝癌细胞株SMMC7721,观察端粒酶活性、细胞增殖和凋亡的情况。 方法 用分子克隆技术构建由U6作为启动子、绿色荧光蛋白基因作为报告基因的核酶真核表达质粒pGTRz-U6及其突变体pGTmRz-U6,并以空质粒pEGFP-C1作为对照。Lipofectamine2000转染人肝癌细胞株SMMC7721,G418筛选阳性克隆。RT-PCR检测核酶及hTERT基因的表达,四甲基偶氮唑盐(MTT)作细胞生长曲线观察其生长情况,TRAP-银染法检测端粒酶活性变化,流式细胞计数(FCM)法检测细胞的凋亡水平。 结果 核酶、突变核酶在SMMC7721中持续表达;凝胶成像系统分析SMMC7721-pEGFP-C1、SMMC7721-mRz、SMMC7721-Rz hTERT基因表达,用SPSS10.0软件对3种细胞进行分析,发现三者hTERT基因表达水平不同(F=47.987,P<0.01);t检验分析得出SMMC7721-Rz hTERT基因表达明显低于SMMC7721-mRz和SMMC7721- pEGFP-C1(t值分别为-7.640和-11.602,P值均<0.01)。SMMC7721-pEGFP-C1和SMMC7721-mRz hTERT表达没有区别(t=-0.178,P>0.05)。TRAP-银染及FCM结果分别显示,随着细胞的分裂,SMMC7721-Rz和SMMC7721-mRz细胞端粒酶活性逐渐降低,凋亡水平逐渐增加,7PDS细胞凋亡率分别是29.86％和9.87％,而对照组SMMC     

三氧化二砷选择性诱导人肝癌细胞凋亡及 相关基因的实验研究

目的 明确三氧化二砷对人肝癌细胞的诱导凋亡作用及其分子机制。方法 用四甲基偶氮唑蓝法、AO/EB荧光染色法、透射与扫描电镜观察、DNA电泳、流式细胞术、TUNEL法及免疫组织化学等方法,观察了三氧化二砷对体外培养的人肝癌细胞株QGY-7701、QGY-7703和正常人肝细胞株L-02的生长活力、细胞凋亡、细胞周期及其相关基因表达的影响。结果 三氧化二砷能显著地抑制人肝癌细胞QGY-7701和QGY-7703的生长,用药后诱导其出现了典型的细胞凋亡形态学和生化学改变,并使细胞周期阻滞于S期,且bcl-2基因表达明显下降,bax和Fas基因表达显著增强;三氧化二砷对正常人肝细胞株L-02无明显作用。结论 三氧化二砷对人肝癌细胞有显著的选择性诱导凋亡作用,且受到多种基因调控,这一结论为应用三氧化二砷治疗原发性肝癌提供了可靠的实验依据。     

Synergistic effect of cell differential agent-II and arsenic trioxide on induction of cell cycle arrest and apoptosis in hepatoma cells

AIM: To illustrate the possible role of cell differential agent-II (CDA-II) in the apoptosis of hepatoma cells induced by arsenic trioxide (As(2)O(3)). METHODS: Hepatoma cell lines BEL-7402 and HepG2 were treated with As(2)O(3) together with CDA-II. Cell surviving fraction was determined by MTT assay; morphological changes were observed by immunofluorescence staining of Hoechst 33,258; and cell cycle and the apoptosis index were determined by flow cytometry (FCM). RESULTS: Cytotoxicity of CDA-II was low. Nevertheless, CDA-II could strongly potentiate arsenic trioxide-induced apoptosis. At 1.0 g/L CDA-II, IC(50) of As(2)O(3) in hepatoma cell lines was reduced from 5.0 micromol/L to 1.0 micromol/L (P<0.01). The potentiation of apoptosis was dependent on the dosage of CDA-II. FCM indicated that in hepatoma, cell growth was inhibited by CDA-II at lower concentrations (<2.0 g/L) primarily by arresting at S and G(2) phase, and at higher concentrations (>2.0 g/L) apoptotic cell and cell cycle arresting at G(1) phase increased proportionally. The combination of two drugs led to much higher apoptotic rates, as compared with the either drug used alone. CONCLUSION: CDA-II can strongly potentiate As(2)O(3)-induced apoptosis in hepatoma cells, and two drugs can produce a significant synergic effect.     

Effect of arsenic trioxide on human hepatoma cell line BEL-7402 cultured in vitro

AIM:To study the effect of a varying concentrations of arsenic trioxide on human hepatoma cell line BEL-7402 cultured in vitro and its mechanism of action.METHODS:The BEL-7402 cells were treated with arsenic trioxide (at the concentrations of 0.5 1 2&mgr;mol/L, respectively) for 4 successive days. The cell growth and proliferation were observed by cell counting and cell-growth curve. Morphologic changes were studied with electronmicroscopy. Flow cytometry was used to assay cell-DNA distribution and the protein expression of Bcl-2 and Bax detected by immunocytochemical method.RESULTS:The cell growth was significantly inhibited by varying concentrations of arsenic trioxide as revealed by cell counting and cell-growth curve, which was dose- and time-dependent. Arsenic trioxide treatment at 0.5, 1 and 2&mgr;mol/L resulted in a sub-G1 cell peak, the apoptosis rate of the control group was 9.31% and that of 0.5&mgr;mol/L arsenic trioxide 15.53%, no significant difference was seen between the two.The apoptosis rates of 1,2&mgr;mol/L arsenic trioxide were 19.10% and 21.87% respectively, which were much higher (both P < 0.05). Decrease of G(0)/G(1) phase cells and increase of S phase cells were observed by flow cytometry, suggesting the inhibition effect of 0.5, 1, 2&mgr;mol/L arsenic trioxide on BEL-7402 cell lay in the G(0)/G(1) phase. Morphologic changes such as intact cell membrane, nucleic condensation, apoptotic body formation were seen under transmission electronmicrescopy, whereas the 0.5mol/L arsenic trioxide-treated BEL-7402 cells showed decrease of nucleocytoplasmic ratio, round nucleus, well-differentiated organelles in the cytoplasm. The processes and microvilli on the cell surface of the experimental groups under scanning electron microscopy were significantly decreased. High expressions of Bcl-2 and Bax were detected in 1 and 2&mgr;mol/L arsenic trioxide-treated cells, these were 46%, 87.33% and 83.08%, 95.83% respectively, among which that of Bax was more significant. Arsenic trioxide treatment at 0.5&mgr;mol/L resulted in a higher expression level of Bcl-2 and lower expression level of Bax,which were 8.81% and 3.83% respectively, as compared with that of the control group (15.33%) (P(1)<0.01, P(2)<0.01).CONCLUSION:Arsenic trioxide not only inhibited proliferation but also induced apoptosis of human hepatoma cell line BEL-7402. The induced-apoptosis effect of 1,2&mgr;mol/L arsenic trioxide was related to the expression level of Bcl-2 and Bax.     

Synergistic effect of cell differential agent-Ⅱ and arsenic trioxide on induction of cell cycle arrest and apoptosis in hepatoma cells

AIM: To illustrate the possible role of cell differential agent-Ⅱ (CDA-Ⅱ) in the apoptosis of hepatoma cells induced byarsenic trioxide (As2O3).METHODS: Hepatoma cell lines BEL-7402 and HepG2 weretreated with As2O3 together with CDA-Ⅱ. Cell survivingfraction was determined by MTT assay; morphologicalchanges were observed by immunofluorescence staining ofHoechst 33 258; and cell cycle and the apoptosis index weredetermined by flow cytometry (FCM).RESULTS: Cytotoxity of CDA-Ⅱ was low. Nevertheless, CDA-Ⅱ could strongly potentiate arsenic trioxide-inducedapoptosis. At 1.0 g/L CDA-Ⅱ, IC50 of As2O3 in hepatoma celllines was reduced from 5.0 μmol/L to 1.0 μmol/L (P＜0.01).The potentiation of apoptosis was dependent on the dosageof CDA-Ⅱ. FCM indicated that in hepatoma, cell growth wasinhibited by CDA-Ⅱ at lower concentrations (＜2.0 g/L)primarily by arresting at S and G2 phase, and at higherconcentrations (＞2.0 g/L) apoptotic cell and cell cyclearresting at G1 phaseincreased proportionally. Thecombination of two drugs led to much higher apoptotic rates,as compared with the either drug used alone.CONCLUSION: CDA-Ⅱ can strongly potentiate As2O3-induced apoptosis in hepatoma cells, and two drugs canproduce a significant synergic effect.     

三氧化二砷对正常肝细胞及肝癌细胞株的影响

目的观察不同浓度Ａｓ２Ｏ３作用不同时间对正常肝细胞及肝癌细胞株的影响。方法０．１２５～２μｍｏｌ／ＬＡｓ２Ｏ３与肝细胞及肝癌细胞株共孵育一定时间后,观察细胞的存活、形态学改变及细胞ＤＮＡ含量的分布。结果１μｍｏｌ／ＬＡｓ２Ｏ３处理的肝癌细胞第５天呈典型的凋亡特征性改变：在形态学上表现为细胞膜完整、染色质固缩、核碎裂、凋亡小体形成;流式细胞仪分析显示,在Ｇ１期细胞前出现亚二倍体峰,琼脂糖凝胶电泳呈凋亡特征性Ｌａｄｄｅｒ带;而正常肝细胞则未见明显改变。结论Ａｓ２Ｏ３可诱导肝癌细胞凋亡。     

三氧化二砷对肝癌细胞表达PTTG1和VEGF的影响及其意义

目的 观察三氧化二砷(As2O3)对人肝癌细胞株BEL-7402和SMMC-7721的作用及其可能机制.方法 采用四甲基偶氮唑蓝(MTT)法检测As2O3对两种细胞的生长活性;用流式细胞仪测定经不同浓度As2O3溶液处理后的两种细胞的周期变化,并用Annexin V-FITC与PI双染法检测细胞凋亡;用实时逆转录-聚合酶链反应(RT-PCR)检测As2O3对两种细胞垂体肿瘤转化基因1(PTTG1)和血管内皮生长因子(VEGF)mRNA表达的影响;用蛋白免疫印迹法(western-blotting)检测As2O3对两种细胞PTTG1和VEGF蛋白表达的影响.结果 As2O3可显著抑制BEL-7402和SMMC-7721细胞的生长,并呈量效关系(r=0.973,P<0.01;r=0.985,P<0.01),半数抑制浓度(IC50)分别为4.38 μmol/L和5.16 μmol/L.BEL-7402和SMMC-7721经As2O3处理后均发生显著凋亡(P<0.01).As2O3能显著下调两种细胞PTTG1和VEGF mRNA及蛋白的表达(P<0.01),并使细胞周期阻滞在G2/M期.结论 As2O3可有效抑制人肝癌细胞的生长增殖,其机制可能与诱导细胞凋亡、阻滞细胞周期及下调PTTG1和VEGF的表达有关.     

The effect of arsenic trioxide on human hepatoma cell line BEL-7402 culturedin vitro

AIM To study the effect of a wide range of concentration of arsenic trioxide on human hepatoma cell lineBEL-7402 and its mechanism.METHODS The BEL-7402 cells were treated with arsenic trioxide (a final concentration of 0.5, 1 and2 μmol/L, respectively) in various durations or for 4 successive days. The cell growth and proliferation wereobserved by cell counting and cell-growth curve. Morphologic changes were studied under electronmicroscopy. Flow cytometry was used to assay cell-DNA distribution and the protein expression of Bcl-2 andBax was detected by immunocytochemical method.RESULTS The cell growth was significantly inhibited by the different concentrations of arsenic trioxide asrevealed by cell counting and cell-growth curve. Arsenic trioxide treatment at 0.5, 1 and 2 μmol/L, resultedin a sub-G1 cell peak. The decreased G0/G1 phase cell and the increased percentage of S phase cell were observed by flow cytometer, suggesting that the inhibiting effect of arsernic trioxide on BEL-7402 cell lay inG0/G1 phase cell. Apoptotis-related morphology, such as intact cell membrane, nucleic condensation,apoptotic body formation, can be seen under the electron microscopy. High protein expression level of Bcl-2and Bax was detected in 1 and 2 μmol/L arsenic trioxide-treated cells, but that of Bax was more significant.Arsenic trioxide treatment at 0.5 μmol/L resulted in higher expression level of Bcl-2 and lower expressionlevel of Bax compared with control (P1<0.01, P2<0.01).CONCLUSION Arsenic trioxide not only inhibited the proliferation but also induced apoptosis of humanhepatoma cell line BEL-7402. The induced-apoptosis effect of 1 and 2 μmol/L arsenic trioxide was relative tothe expression level of Bcl-2 and Bax.     

三氧化二砷对人恶性黑素瘤细胞株A375生长和凋亡影响的研究

目的研究三氧化二砷（As2O3）对人恶性黑素瘤细胞株A375的生长抑制与促凋亡作用。方法采用四甲基偶氮唑蓝（MTT）还原法检测As2O3对黑素瘤细胞的抑制作用；倒置显微镜、电镜观察细胞形态变化和凋亡特征；流式细胞仪分析DNA含量和检测细胞周期。结果1．0、2．0、4．0、8．0、16．0μmol／L As2O3均能抑制A375细胞的生长，且抑制率具有浓度和时间依赖性。8．0和16．0μmol／L组主要表现细胞毒性作用；4．0μmol／L组作用72h后，A375细胞出现较典型的凋亡形态特征，流式细胞仪检测到亚二倍体凋亡峰，同时出现S期阻滞。结论As2O3能有效的抑制人恶性黑素瘤细胞株A375的生长并促进其凋亡。     

三氧化二砷对人恶性黑色素瘤A375细胞增殖及新癌基因PPO表达的影响

目的 探讨三氧化二砷对人恶性黑素瘤A375细胞株细胞周期、增殖、凋亡及新癌基因PPO(proliferation and phosphorylation oncogene)表达的影响.方法 培养人恶性黑色素瘤A375细胞株,采用 MTT法检测三氧化二砷在不同浓度和不同时间下对A375细胞增殖的影响,流式细胞术分析三氧化二砷对细胞周期及凋亡的影响,倒置相差显微镜观察药物处理后对人A375细胞的细胞分化及形态的影响,免疫细胞化学(SP)法检测三氧化二砷对PPO蛋白表达的影响.结果 MTT法证实三氧化二砷在1～10 μmol/L浓度范围内对A375细胞有明显的增殖抑制作用,呈现明显的剂量和时间依赖效应关系.流式细胞术检测发现,随着药物浓度的增加,G0/G1的细胞逐渐减少(P＜0.01),S期的比例显著增加,出现S期阻滞.倒置显微镜观察发现细胞出现典型凋亡细胞形态学改变.免疫细胞化学法检测PPO蛋白主要表达于A375细胞胞浆内,染色呈棕黄色.三氧化二砷作用48 h后,随着药物浓度的增加,PPO的染色程度逐渐减弱,差异具有显著性(P＜0.01).结论 三氧化二砷能够显著抑制A375细胞株增殖,并诱导凋亡发生,且与三氧化二砷的浓度和作用时间成正相关,其作用机制可能是通过下调新癌基因PPO的表达发挥作用.     

Effect of arsenic trioxide on viability, proliferation, and apoptosis in human megakaryocytic leukemia cell lines.

Arsenic trioxide (As2O3) has been demonstrated to be effective for the treatment of acute promyelocytic leukemia (APL) and to inhibit proliferation and produce apoptosis in the APL cell line NB4. To determine if As2O3 might be useful for the treatment of other lineages, we investigated the effects of As2O3 on viability, proliferation, and induction of apoptosis in the megakaryocytic leukemia cell lines HEL, Meg-01, UT7, and M07e. Our results showed that As2O3, at concentrations of 0.1-2.0 microM, causes a dose- and time-dependent inhibition of survival and growth in all four megakaryocytic leukemia cell lines studied. In contrast, As2O3 at similar concentrations had no effects on either viability or growth of the nonmegakaryocytic leukemia cell line HL60 and two human breast cancer cell lines, ZR75 and MCF7. In situ end-labeling of DNA fragments (TUNEL assay) indicated that As2O3, at concentrations of 0.5-2 microM, could significantly induce apoptosis in the aforementioned four megakaryocytic leukemia cell lines, but not in the nonmegakaryocytic HL60, ZR75, and MCF7 cell lines. These results were confirmed using conventional morphologic assessment and the DNA ladder assay. Induction of apoptosis in arsenic-treated Meg-01 and UT7 cells was accompanied by a dose-response decrease of Bcl-2 protein, whereas As2O3 had no effect on this measurement in HL60, ZR75, and MCF7 cell lines. Pertinently, these concentrations of As2O3 produced identical changes in the characteristics of the APL cell line NB4. Collectively, these data demonstrate that As2O3 can selectively inhibit growth and induce apoptosis in megakaryocytic leukemia cell lines. The use of As2O3 for the treatment of malignant megakaryocytic disorders should be considered.