Mcl-1 siRNA对TRAIL诱导胃癌细胞凋亡的影响

摘要

Objective To explore the effect of Mcl-1 small interference RNA ( siRNA) on tumor necrosis factor-re-lated apoptosis-inducing ligand ( TRAIL)-induced apoptosis in gastric cancer HGC-27 cells. Methods The apop-totic rates of cells treated with TRAIL and pan-caspase inhibitor ( z-VAD-fmk) alone or combination were measured by propidium iodide (PI) method using flow cytometry. The activation of caspase-3, cleavage of PARP-1, as well as the protein level of anti-apoptotic Bcl-2 proteins Bcl-2, Bcl-XL and Mcl-1 before and after TRAIL treatment were monitored by Western blot analysis. Transfection of Mcl-1 siRNA was performed using Lipofectamine 2000 reagent. The efficiency of gene silencing was quantified by Western blot and the effect of Mcl-1 siRNA on TRAIL-induced apoptosis was measured using PI method. Results HGC-27 cells were resistant to TRAIL-induced apoptosis, and z-VAD-fmk pretreatment could block apoptosis nearly completely. Activation of caspase-3 and cleavage of PARP-1 occurred in the late stage of apoptosis. The expression levels of Bcl-2, Bcl-XL and Mcl-1 were not altered after exposure to TRAIL. Transfection with Mcl-1 siRNA could obviously downregulate the expression evel of Mcl-1 in HGC-27 cells and enhanced the sensitivity of cells to TRAIL-induced apoptosis. Conclusion Overexpression of Mcl-1 may account for the resistance of HGC-27 cells to TRAIL.ownregulation of Mcl-1 by siRNA can effectively enhance the sensitivity of HGC-27 cells to TRAIL-induced apoptosis.%目的 探讨转染髓样细胞白血病( Mcl-1 ) siRNA特异性沉默Mcl-1 基因对肿瘤坏死因子相关的凋亡诱导配体( TRAIL)诱导胃癌细胞HGC-27 凋亡的影响. 方法 采用碘化丙啶( PI)染色法流式细胞术分析TRAIL单独作用的细胞凋亡率以及广谱caspase抑制剂z-VAD-fmk对细胞凋亡的抑制作用;Western blot法分析TRAIL处理前后半胱天冬酶-3(caspase-3)和聚腺苷二磷酸核糖聚合酶-1(PARP-1)的活化以及抗凋亡的Bcl-2、Bcl-XL 及Mcl-1的蛋白表达情况;采用Lipofectamine 2000 转染 Mcl-1 siRNA 入 HGC-27 细胞, Western blot 法验证基因沉默效果,流式细胞术分析转染后细胞凋亡率的变化. 结果 HGC-27细胞对TRAIL不敏感, 48 h的凋亡率仅为( 20. 65 ± 3. 23 )%, z-VAD-fmk能几乎完全阻止TRAIL诱导的凋亡;TRAIL作用晚期caspase-3活化、PARP-1裂解,Bcl-2、Bcl-XL 及Mcl-1在TRAIL处理前后没有明显的变化;Mcl-1 siRNA转染后能显著降低细胞中 Mcl-1的蛋白表达水平,且细胞转染Mcl-1 siRNA后再加入TRAIL处理,细胞凋亡率明显增加. 结论 Mcl-1的高表达可能与HGC-27细胞对TRAIL抵抗有关,Mcl-1 siRNA沉默Mcl-1基因能增加HGC-27细胞对TRAIL的敏感性.