线粒体促凋亡蛋白促进化疗药物诱导膀胱癌细胞凋亡的分子学机理研究

Molecular mechanism of Smac gene enhancing the induction of chemotherapeutic drug on bladder cancer apoptosis

目的 探讨线粒体促凋亡蛋白 (Smac)促进化疗药物诱导膀胱癌细胞凋亡的分子学机理。 方法 脂质体介导Smac基因转染膀胱癌T2 4细胞 3d后 ,低剂量丝裂霉素诱导凋亡启动 ,MTT比色分析检测癌细胞生长活性 ,流式细胞术检测细胞凋亡 ;免疫组织化学法和逆转录聚合酶链反应检测Smac、XIAP、caspase 3的表达。 结果 各组癌细胞在低剂量丝裂霉素诱导下均出现凋亡 ,0 .0 5mg/ml、0 .0 0 5mg/ml丝裂霉素处理的T2 4细胞凋亡率分别为 18.84 %、10 .72 % ,转染Smac后经 0 .0 5mg/ml、0 .0 0 5mg/ml丝裂霉素处理的T2 4细胞凋亡率分别为 33.5 2 %、2 6 .2 4 % ,差异有显著性意义 (P1<0 .0 5、P2 <0 .0 1) ;同组凋亡相关基因XIAP表达下降、caspase 3表达上调 ,其表达差异均有统计学意义 (P <0 .0 5 )。 结论 Smac在癌细胞中的活化表达可以明显增强细胞在刺激信号下的凋亡 ,其作用机理是通过抑制凋亡抑制蛋白IAPs ,解除了对凋亡下游效应半胱氨酸蛋白酶caspase的抑制活性。

Objective To investigate the enhancing effect and molecular mechanism of Smac gene on the apoptosis induced by chemotherapeutic drug in the bladder cancer cell line T24. Methods The Smac gene was transfected into bladder cancer cell line T24 through the induction of liposome.The intrinsic Smac,XIAP,caspase 3 expression levels were detected by immunocytochemistry and RT PCR.The in vitro cellular growth activities were assayed by MTT colorimetry; the apoptosis rate was assayed by the flowcytometry. Results In comparison with the control cells, the apoptosis rate of T24 cells induced by mitomycin C was enhanced by transfected Smac gene.The apoptosis rates of T24 cells were 18.84% and 10.72% by treatment of 0.05 mg/ml and 0.005 mg/ml mitomycin C;while after Smac gene transfection the rates were 33.52%and 26.24%. There were significant differences between the transfected groups and the control groups ( P 1<0.05, P 2<0.01).Accordingly the level of XIAP was down regulated and caspase 3 was up regulated.The differences were significant ( P <0.05). Conclusions The Smac can inhibit IAPs,enhance caspase activity and the apoptosis rate of T24 cells induced by mitomycin C,which provides useful experimental evidence for bladder cancer therapy.