基于caspase-3/Bcl-2/Bax信号通路探究SMAC基因对肺腺癌细胞紫杉醇敏感度及细胞活性的影响

目的 基于caspase-3/Bcl2/Bax信号通路探究SMAC基因对肺腺癌细胞紫杉醇敏感度及细胞活性的影响。方法 建立肺腺癌紫杉醇耐药细胞株A549/Taxol，将细胞分为pcDNANC组（转染pcDNA-NC空白载体）、pc DNA-SMAC组（转染pc DNA-SMAC载体）、siRNA-NC组（转染siRNANC空病毒载体）和siRNA-SMAC组（转染siRNA-SMAC慢病毒载体）。qRT-PCR法检测细胞中SMACmRNA表达；MTT法检测细胞敏感度；克隆实验法检测细胞增殖能力；Transwell法检测细胞侵袭能力；流式细胞术检测细胞凋亡能力；Western blot法检测细胞中caspase-3、Bcl-2和Bax蛋白表达。结果 肺腺癌A549细胞较BEAS-2B正常细胞中SMAC mRNA表达明显降低（P<0.05）。pcDNA-SMAC组较pcDNA-NC组细胞中SMAC mRNA表达显著升高（P<0.05）。和siRNA-NC组相比，siRNA-SMAC组细胞中SMAC mRNA表达显著降低（P<0.05）。和pcDNA-NC组相比，pcDNA...     

白藜芦醇对肺癌紫杉醇耐药细胞的增殖抑制作用及其机制

目的：研究白藜芦醇作用后人肺腺癌紫杉醇耐药细胞对紫杉醇敏感性的改变,并探讨其作用机制。方法：建立人肺腺癌紫杉醇耐药细胞A549/Taxol-R,用不同浓度白藜芦醇、紫杉醇单独或联合干预A549/Taxol-R细胞,MTT法检测细胞增殖抑制率;概率单位法计算半数抑制浓度（IC₅₀）;观察不同浓度白藜芦醇处理后,紫杉醇对A549/Taxol-R细胞IC₅₀的变化;流式细胞术检测细胞凋亡水平;Western blot检测凋亡相关蛋白Bax、Bcl-2和Caspase-3的表达。结果：白藜芦醇对A549/Taxol-R细胞增殖的抑制率具有浓度和时间的双重依赖性（P均 < 0.05）。白藜芦醇处理后,紫杉醇对A549/Taxol-R细胞的IC₅₀值下降,从（17.50±1.24）μg/mL降低至（4.18±0.62）μg/mL。白藜芦醇和紫杉醇联合干预的A549/Taxol-R细胞凋亡率、坏死率高于单独干预组（P < 0.05）,联合干预组A549/Taxol-R细胞的Bax、Caspase-3的表达较单独干预组上调,而Bcl-2的表达则相对下调（P < 0.05）。结论：白藜芦醇可能通过促进细胞的凋亡来增强人肺腺癌紫杉醇耐药细胞对紫杉醇的敏感性,其机制可能和促进Bax、Caspase-3的表达,下调Bcl-2的表达有关。     

下调CK2α基因表达抑制肺腺癌A549细胞的增殖和凋亡

目的:探讨下调CK2α基因表达后对肺腺癌A549细胞的影响.方法:构建pSilencerTM4.1-shCK2α-eGFP慢病毒表达载体,建立稳定干扰CK2α表达的A549细胞株.利用MTT、克隆形成、凋亡实验检测干扰CK2α基因表达后,A549细胞的增殖和凋亡的能力.利用Western blot检测细胞凋亡相关蛋白Caspase-3、Caspase-8、Bcl-xl、Bcl-2的表达.结果:下调CK2α基因表达后肺腺癌A549细胞增殖能力减低,促进细胞凋亡.细胞凋亡相关蛋白Caspase-3、Caspase-8上调,但Bcl-xl、Bcl-2蛋白明显下调.结论:下调CK2α基因表达后抑制肺腺癌A549细胞增殖、促进凋亡.     

榄香烯乳对人肺腺癌 A549 细胞株凋亡蛋白表达的影响

目的:探讨榄香烯乳对人肺腺癌A549细胞株凋亡蛋白表达的影响.方法:体外培养人肺腺癌A549细胞株,四甲基偶氮唑蓝比色试验法(MTT法)测定不同浓度榄香烯乳在不同作用时间下对A549细胞株的生长抑制作用.IC软件计算10％的细胞抑制浓度(IC10).免疫细胞化学染色观察榄香烯乳作用24h后A549细胞的Bcl-2、Bax、Survivin及VEGF蛋白的表达变化.结果:榄香烯乳对人肺腺癌A549细胞株增殖具有明显抑制作用,呈时间和剂量依赖性.榄香烯乳作用24h后IC10为43.49μg/ml,Bax蛋白表达增加,细胞质着色增强;Bcl-2蛋白表达下降,细胞质着色减弱;增殖蛋白Survivin和VEGF的表达下降,且具有药物浓度相关性.结论:榄香烯乳对人肺腺癌A549细胞株有明显的抑制作用,榄香烯乳可上调凋亡相关蛋白表达、诱导凋亡.     

Croton Tiglium Extract Induces Apoptosis via Bax/Bcl-2 Pathways in Human Lung Cancer A549 Cells

Objective: To investigate the impact of a Croton tiglium extract on cellular proliferation and apoptosis in a non-small cell lung cancer cell line (A549) in vitro. Methods: A Croton tiglium seed methanol extract was prepare and assessed for effects on A549 cells regarding cellular proliferation, apoptotic rates, and expression of apoptosis related genes and proteins using real-time PCR and immunofluorescence. Results: The tested Croton tiglium extract inhibited A549 cell proliferation in a dose- and time-dependent manner, with significant elevation of apoptotic indexes at various concentrations after 24 h. In addition, rates in both early and late stages were higher in treated than untreated groups, the 100 μg/ml dose causing the highest levels of apoptosis. RT-PCR showed that A549 cells treated with 100 μg/ml Croton tiglium extract for 24 h has markedly higher Bax mRNA expression levels and obviously lower Bcl-2 expression levels than controls, equivalent results being observed for proteins by immunofluorescence. However, the mRNA expression levels of Fas and caspase-8 were not significantly altered. Conclusion: A Croton tiglium extract can inhibit proliferation of A549 cells and promote apoptosis though Bax/Bcl-2 pathways.     

亚砷酸诱导肺腺癌A549细胞凋亡及对MAPK／ERK信号通路的影响

目的探讨亚砷酸对肺腺癌A549细胞凋亡、MAPK／ERK信号通路的影响及其作用机制。方法体外培养肺腺癌A549细胞,实验组采用不同浓度(1、3、6 μmol／L)亚砷酸处理,对照组加入等体积的二甲基亚砜(DMSO),MTT法检测细胞增殖率,FMC法检测细胞周期分布与细胞凋亡率,Hoechst 33342观察凋亡小体,Western blotting检测Bcl 2、Bax、p53、Caspase 3及MAPK／ERK信号通路相关蛋白表达水平,RT PCR检测PCNA、CDK2、CyclinA1表达量。结果实验组肺腺癌A549细胞增殖率、凋亡率、凋亡小体数量随着亚砷酸处理时间延长而降低,且存在剂量反应效应(P<005);Western blotting结果显示，实验组肺腺癌A549细胞中Bax、p53、Caspase 3、p JNK／JNK及p38蛋白水平高于对照组,而Bcl 2、p ERK／ERK蛋白含量低于对照组,均呈剂量依赖性,差异均有统计学意义(P<005);RT PCR结果显示实验组肺腺癌A549细胞PCNA、CDK2、CyclinA1表达量低于对照组,均呈剂量依赖性,差异均有统计学意义(P<005)。结论亚砷酸可以通过下调细胞周期基因水平、上调细胞凋亡相关因子含量、降低MAPK／ERK信号传导,来诱导肺腺癌A549细胞凋亡。     

miR-194-5p调控LMNB1抑制肺腺癌细胞的生长转移

目的:探究miR-194-5p调控LMNB1对肺腺癌细胞生长转移的作用。方法:实时荧光定量PCR（qRT-PCR）实验检测肺腺癌组织和癌旁组织中miR-194-5p、LMNB1表达水平。体外培养肺腺癌细胞A549,分为对照组、miR-194-5p mimics阴性对照组、miR-194-5p mimics组。转染处理后,CCK-8实验检测各组A549细胞增殖情况,比较各组细胞活力;流式细胞实验检测各组A549细胞凋亡率;细胞划痕及Transwell小室侵袭实验分别检测各组A549细胞迁移、侵袭力,比较各组细胞迁移、侵袭数;免疫印迹实验检测各组A549细胞凋亡蛋白caspase-3、Bax和上皮间质转化（epithelial-mesenchymal transition,EMT）相关蛋白E-cadherin、Vimentin表达;qRT-PCR实验及免疫印迹实验分别检测各组A549细胞miR-194-5p、LMNB1 mRNA表达及LMNB1蛋白表达。结果:相比癌旁组织,肺腺癌组织中miR-194-5p表达水平明显降低（P＜0.05）,LMNB1表达水平明显升高（P＜0.05）。相比对照组,miR-194-5p mimics组A549细胞活力、细胞迁移数、细胞侵袭数、LMNB1 mRNA表达水平、Vimentin和LMNB1蛋白表达水平显著降低（P＜0.05）,细胞凋亡率、miR-194-5p表达、caspase-3、Bax和E-cadherin蛋白表达水平显著升高（P＜0.05）。miR-194-5p mimics阴性对照组A549细胞上述各指标与对照组相比差异无统计学意义（P＞0.05）。结论:miR-194-5p可下调LMNB1表达,抑制肺腺癌细胞增殖,促进其凋亡,并降低其迁移及侵袭能力。     

斑蝥素诱导人肺癌A549细胞凋亡及其分子机制的研究

目的探讨斑蝥素诱导人肺癌A549细胞的凋亡作用及其分子机制。方法采用MTT法检测斑蝥素对A549细胞的增殖抑制作用;以光镜、电镜、流式细胞仪、Annexin V—FITC标记法和DNA凝胶电泳检测细胞凋亡;以蛋白印迹法分析斑蝥素对bcl-2、Bax和Survivin蛋白表达的影响。结果斑蝥素能抑制A549细胞的增殖;斑蝥素处理A549细胞后,光镜与电镜下可见到明显的凋亡细胞;细胞周期的G1期前有低于二倍体细胞的凋亡峰;Annexin V-FITC标记法的定量检测进一步证实了斑蝥素诱导细胞凋亡的作用;DNA凝胶电泳显示出典型的凋亡细胞特征;蛋白印迹检测表明斑蝥素可使Bax表达升高,bcl-2和Survivin表达下降。结论斑蝥素能显著抑制A549细胞增殖,诱导细胞凋亡,并主要通过调节Bax、bcl-2和Survivin等蛋白的表达来实现。     

番荔枝内酯单体squamocin诱导人肺腺癌A549细胞凋亡的实验研究

目的 观察番荔枝内酯单体squamocin对人肺腺癌A549细胞的体外增殖抑制及诱导凋亡的作用,并探讨squamocin诱导肿瘤细胞凋亡的机制。方法 MTT法检测不同浓度的squamocin对人肺腺癌A549细胞体外增殖的影响;流式细胞仪检测squamocin干预在不同时间点对人肺腺癌A549细胞凋亡率的影响;Western blotting检测squamocin干预前后细胞凋亡相关蛋白caspase-3、Bax和Bcl-2的表达情况。结果 MTT法显示,squamocin对人肺腺癌A549细胞的体外抑制作用随着squamocin浓度的增加和作用时间的延长而增强,24、48、72h半数抑制浓度（IC50）分别为16.54、9.28、6.17μg／ml;流式细胞仪检测显示,在24、48、72h实验组人肺腺癌A549细胞凋亡率之间及其与阴性对照组比较,差异均有统计学意义（P＜0.01）,其中实验组72h的细胞凋亡率最高,为（51.87±1.79）％Western blotting显示,squamocin干预后细胞凋亡相关蛋白caspase-3和Bax表达上调,Bcl-2表达明显下调。结论 squamocin可诱导人肺腺癌A549细胞凋亡,这可能与squamocin上调细胞凋亡相关蛋白caspase-3、Bax表达以及降低抑制细胞凋亡基因Bcl-2表达有关。     

Induction of Apoptosis and Cell Cycle Arrest by Dorema Glabrum Root Extracts in a Gastric Adenocarcinoma (AGS) Cell Line

Objective: Dorema glabrum Fisch. & C.A. Mey is a perennial plant that has several curative properties. Anti-proliferative activity of seeds of this plant has been demonstrated in a mouse fibrosarcoma cell line. The aim of the present study was to evaluate cytotoxicity of D. glabrum root extracts in a human gastric adenocarcinoma (AGS) cell line and explore mechanisms of apoptosis induction, cell cycle arrest and altered gene expression in cancer cells. Materials and Methods: The MTT assay was used to evaluate IC50 values, EB/AO staining to analyze the mode of cell death, and flow cytometry to assess the cell cycle. Quantitative real-time polymerase chain reaction (qRT-PCR) amplification was performed with apoptosis and cell cycle-related gene primers, for cyclin D1, c-myc, survivin, VEGF, Bcl-2, Bax, and caspase-3 to determine alteration of gene expression. Results: Our results showed that n-hexane and chloroform extracts had greatest toxic effects on gastric cancer cells with IC50 values of 6.4 μg/ml and 4.6 μg/ml, respectively, after 72 h. Cell cycle analysis revealed that the population of treated cells in the G1 phase was increased in comparison to controls. Cellular morphological changes indicated induction of apoptosis. In addition, mRNA expression levels of Bax and caspase-3 were increased, and of bcl-2 survivin, VEGF, c-myc and cyclin D1 were decreased. Conclusion: Our study results suggest that D. glabrum has cytotoxic effects on AGS cells, characterized by enhanced apoptosis, reduced cell viability and arrest of cell cycling.     

唑来膦酸对肺癌95D细胞周期阻滞和诱导凋亡的作用机制

目的 研究唑来膦酸对肺癌95D细胞的细胞周期阻滞及诱导凋亡作用.方法 采用二苯基溴化四氮唑蓝法检测唑来膦酸对肺癌95D细胞增殖的影响;采用流式细胞仪检测唑来瞵酸作用后肺癌95D细胞的细胞周期和凋亡的变化,并在光镜和电镜下观察细胞凋亡的形态变化;采用Western blot和逆转录聚合酶链反应检测唑来膦酸对肺癌95D细胞凋亡相关基因ERK1/ERK2、bcl-2、bax和survivin表达水平的影响.结果 唑来膦酸对肺癌95D细胞的增殖抑制作用呈时间和浓度依赖性,94.0% μmol/L唑来膦酸作用6 d时,抑制率达89.8%.随着唑来膦酸作用时间的延长,G1期细胞数量增多,G2期和S期细胞减少,凋亡细胞的数最逐渐增多.光镜和电镜均观察到细胞出现了相应的凋亡形态学变化.细胞凋亡相关基因ERK、bcl-2和survivin的表达水平下降,bax的表达水平增高.结论 唑来膦酸对肺癌95D细胞的细胞周期有阻滞作用,并能诱导其凋亡.     

Piperine induces apoptosis of lung cancer A549 cells via p53-dependent mitochondrial signaling pathway

The aim of this study was to evaluate the cytotoxic and apoptotic effects of piperine on human lung cancer A549 cells and to explore its mechanisms. Piperine was found to exert the greatest cytotoxic effect against A549 cells in a dose-dependent manner, whereas it showed no effect on WI38 human lung fibroblasts. This cell growth-inhibitory effect might be attributed to cell DNA damage and cytotoxic effects. Besides, piperine had the ability to cause cell cycle arrest in G2/M phase and to activate caspase-3 and caspase-9 cascades in A549 cells. Furthermore, piperine-induced apoptosis could be blocked by the broad caspase inhibitor z-VAD-fmk in majority. In addition, piperine treatment decreased Bcl-2 protein expression, but increased Bax protein expression in A549 cells, which were positively correlated with an elevated expression of p53 compared to control. Taken together, these results suggested that piperine could induce p53-mediated cell cycle arrest and apoptosis via activation of caspase-3 and caspase-9 cascades, as well as increasing the Bax/Bcl-2 ratio. Thus, piperine could be developed as an effective antitumor agent in the prevention and treatment of lung cancer without toxicity to the host.     

Testin在非小细胞肺癌组织和细胞株中的表达及其对癌细胞恶性生物学行为的影响

目的:探讨Testin基因(TES)在非小细胞肺癌(NSCLC)组织和细胞株中的表达及其对人肺癌A549细胞增殖、迁移、侵袭和凋亡的影响.方法:收集2015年1月至2015年12月在华中科技大学同济医学院附属同济医院手术切除的27例NSCLC患者的癌组织及癌旁组织标本,用Western blotting法检测癌组织和癌旁组织,以及正常人胚肺成纤维细胞株MRC5和肺癌细胞株A427、A549、H1299、LK2、PC9和SW900中TES蛋白的表达水平.应用短发卡RNA(shRNA)瞬时转染肺癌细胞株A549干扰TES基因的表达,并进一步检测TES低表达对A549细胞增殖、迁移、侵袭以及凋亡的影响,同时检测凋亡相关蛋白Bax、Bcl-2和Cas-pase-3的表达.结果:在NSCLC组织和细胞株中TES蛋白的表达明显下降(均P＜0.05).shTES干扰A549细胞后,TES mRNA和蛋白表达水平均显著下降(均P＜0.05).抑制TES表达显著增强A549细胞的增殖[(2.75±0.04) vs (1.79±0.06),P＜0.05]、迁移[(52.3±2.6)％s(19.7±1.4)%,P＜0.05]和侵袭能力[(31.2±3.9)％vs(14.5±4.1)％,P＜0.05],同时降低了细胞凋亡率[(8.2±1.1)％s(23.1±1.7)％,P＜0.05].TES低表达使A549细胞Bax和Caspase-3蛋白表达明显下降(P＜0.05)、Bcl-2蛋白表达明显升高(P＜0.05).结论:TES在NSCLC组织中呈低表达,TES表达下调具有促进肺癌细胞的增殖、迁移、侵袭并抑制凋亡等生物学效应,其有可能成为肺癌治疗一个新靶点.     

白花檵木对肺腺癌A549细胞增殖的抑制作用

目的 探讨白花檵木粗提物对肺腺癌A549细胞体外增殖的影响.方法 CCK-8法检测不同浓度白花檵木粗提物对A549细胞增殖的影响;集落形成实验检测白花檵木粗提物对A549细胞克隆生长能力的影响;流式细胞Annexin V-APC/PI双染法检测白花檵木粗提物诱导A549细胞凋亡的情况;免疫印迹法检测白花檵木粗提物处理后...     

西咪替丁对人肺腺癌A549细胞增殖和凋亡的影响

摘要：目的研究西咪替丁对其增殖及凋亡的影响并探讨其可能的机制。方法分别以不同浓度的西咪替丁处理A549细胞48 h后,采用MTT法测细胞存活率,流式细胞术测细胞凋亡率,Western blot测Bcl-2和Bax蛋白表达水平情况,观察西咪替丁对A549细胞增殖和凋亡的影响。结果经西咪替丁干预48 h后,A549细胞的增殖受到明显抑制,凋亡增加,且该抑制呈药物浓度依赖性增加。Western blot检测显示随着西咪替丁浓度增加,Bcl-2蛋白的表达减少,而Bax蛋白的表达增加。结论西咪替丁预处理能抑制A549细胞的增殖,促进其凋亡,其机制可能与其下调细胞Bcl-2蛋白表达,上调Bax蛋白表达有关。     

Apoptotic effect of citrus fruit extract nobiletin on lung cancer cell line A549 in vitro and in vivo

Lung cancer is the leading cause for cancer-related death worldwide and the effectiveness of current treatments is very limited. Here we reported that Nobiletin, an effective component of citrus fruit, has antiproliferative activity on lung cancer cells both in vitro and in vivo. Cell viability and clonogenic assay showed that Nobiletin dose-dependently suppressed the proliferation of human lung adenocarcinoma cell line A549 cells, while has having a minimal effect on human umbilical vein endothelial cell line ECV-304 cells. DNA fragment assay and comet assay demonstrated that Nobiletin induced A549 cell apoptosis. Nobiletin-induced cell cycle arrest at G(2)/M phase was detected by Flow cytometric analysis. In addition, Western blot analysis revealed that A549 cells pretreated with Nobiletin showed decreased Bcl-2 and increased Bax protein expression, which were positively correlated with elevated expression of p53 compared to control. Furthermore, Nobiletin had overt inhibitory effect on the tumor growth in nude mice model was observed in vivo. Taken together, these results suggest that Nobiletin could induce p53-mediated cell cycle arrest and apoptosis via modulated the Bax:Bcl-2 protein ratio, is effective as a potent antitumor agent on lung tumors.     

Ponicidin, an ent-kaurane diterpenoid derived from a constituent of the herbal supplement PC-SPES, Rabdosia rubescens, induces apoptosis by activation of caspase-3 and mitochondrial events in lung cancer cells in vitro

Ponicidin, an ent-kaurane diterpenoid derived from a constituent of the herbal supplement PC-SPES, Rabdosia rubescens, is recently reported to have anti-tumor effects on a large variety of cancers. In this study, we demonstrate that ponicidin exhibits cytotoxicity, induces apoptosis, disrupts the mitochondrial membrane potential, and triggers the activation of caspase-3, -8 and -9 in lung cancer A549 and GLC-82 cells. Ponicidin treatment of lung cancer cells caused downregulation of anti-apoptotic protein Bcl-2 and survivin as well as upregulaton of pro-apoptotic protein Bax in a time dependent manner when apoptosis ocurred. Ponicidin induced activation of caspase-3 can be blocked by a caspase-3-specific inhibitor z-DEVD-FMK Furthermore, the caspase-8-specific inhibitor z-IETD-FMK could block the ponicidin-induced activation of caspase-3, PARP cleavage, and prevented the release of cytochrome c from mitochondria into the cytoplasm. This indicate that activated caspase-8 initiates the release of cytochrome c during ponicidin-induced apoptosis. We therefore conclude that ponicidin has significant apoptosis-inducing effects by activation of caspase-3 -8, and -9 as well as downregulation of anti-apoptotic protein Bcl-2, survivin and upregulation of pro-apoptotic protein Bax, with caspase-8 acting as an upstream activator. The data offer a potential mechanism for ponicidin-induced apoptosis in lung cancer cells, suggesting that ponicidin may severve as an effective reagent for the treatment of lung cancer, and that in vivo anti-cancer effects as well as its potential clinical effectiveness need further investigation.     

重楼皂甙Ⅰ对肺腺癌细胞株PC9增殖及凋亡的影响

[目的]评价重楼皂甙Ⅰ对肺腺癌细胞株PC9增殖和凋亡的影响.[方法]以体外培养的肺腺癌细胞株PC9为研究对象,MTT法检测重楼皂甙Ⅰ对PC9细胞增殖的抑制作用,流式细胞仪检测重楼皂甙Ⅰ对PC9细胞周期的影响,Annexin-V-FITC/PI双染法检测重楼皂甙Ⅰ对PC9细胞凋亡的影响,Western blot法检测重楼皂甙Ⅰ对PC9细胞Bcl-2、Bax、caspase-3蛋白表达的影响.[结果]不同浓度重楼皂甙Ⅰ能有效抑制PC9细胞的增殖,且呈时间浓度依赖性(P＜0.01).2.5.μg/ml重楼皂甙Ⅰ作用PC9细胞12h、24h、48h后,出现G2/M期阻滞.2.5μg/ml重楼皂甙Ⅰ作用PC9细胞24h、48h后,细胞凋亡率明显增加,与对照组相比,具有统计学差异(P＜0.01).2.5μg/ml重楼皂甙Ⅰ作用PC9细胞48h后,Bcl-2蛋白表达降低、Bax及caspase-3蛋白表达增加,与对照组相比,亦具有统计学差异(P＜0.01).[结论]重楼皂甙Ⅰ能抑制PC9细胞的体外增殖,且抑制作用表现出时效和量效关系,其机制可能与G2/M期阻滞、促进细胞凋亡、降低Bcl-2蛋白表达、增加Bax及caspase-3蛋白表达有关.     

Tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis is inhibited by Bcl-2 but restored by the small molecule Bcl-2 inhibitor, HA 14-1, in human colon cancer cells.

PURPOSE: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent that induces apoptosis in multiple tumor cell types while sparing most normal cells. We determined the effect of ectopic Bcl-2 expression on TRAIL-induced apoptosis and whether the small molecule Bcl-2 inhibitor, HA14-1, could increase TRAIL sensitivity. EXPERIMENTAL DESIGN: SW480 human colon cancer cells were stably transfected with the PC3-Bcl-2 plasmid or vector alone. Cells were incubated with recombinant human TRAIL +/- HA14-1 or caspase-9 inhibitor (Z-LEHD-FMK). Apoptosis was analyzed by Annexin V-fluorescein isothiocyanate labeling and DNA fragmentation factor 45 (DFF45) cleavage. Clonigenic survival was also studied. Caspase activation was determined by immunoblotting or colorimetric assay. The cytosolic expression of Bid, Bax, and XIAP and release of cytochrome c and Smac/DIABLO were determined by immunoblotting. RESULTS: Bcl-2 overexpression partially protected SW480 cells from a dose-dependent induction of apoptosis by TRAIL, as did a caspase-9 inhibitor, and increased their clonogenic survival. Bcl-2 overexpression attenuated TRAIL-induced cleavage of caspase-8, indicating its activation upstream and downstream of mitochondria, as well as cleavage of Bid and caspase-3. Bcl-2 inhibited TRAIL-induced Bax translocation, cytosolic release of cytochrome c and Smac/DIABLO, and the downstream cleavage of XIAP and DFF45. Coadministration of HA14-1 and TRAIL increased apoptosis in SW480/Bcl-2 cells by restoring Bax redistribution and cytochrome c release. CONCLUSIONS: Bcl-2 confers apoptosis resistance to TRAIL by inhibiting a mitochondrial amplification step and by inactivating downstream XIAP in SW480 cells. HA14-1 reversed Bcl-2-mediated TRAIL resistance, suggesting a novel strategy for increasing TRAIL sensitivity in Bcl-2-overexpressing colon cancers.