目的研究凋亡抑制蛋白Livin靶向RNA干扰MDA-MB-231对细胞增殖和凋亡的影响,探讨其可能的机制。方法构建3个靶向Livin的siRNA真核表达载体,分别转染乳腺癌细胞MDA-MB-231后,通过RT-PCR、Western blot技术检测干扰前后MDA-MB-231细胞Livin、Caspase-3和Smac/DIABLO在mRNA、蛋白水平的表达;采用MTT法检测对细胞增殖的抑制作用,流式细胞法测细胞周期,TUNEL法检测细胞凋亡以及观察细胞形态变化。结果成功构建了针对Livin基因的3个特异性siRNA表达载体。它们不同程度地抑制了MDA-MB-231细胞Livin基因的表达,以si-Livin2抑制效率最高,它对Livin的mRNA和蛋白的抑制率分别达76.4%,70.2%。si-Livin2转染48 h后,与未转染组相比,细胞增殖活力受到抑制,转染48 h抑制率达36.1%。细胞周期重新分布,G0/G1期上升为(71.75±1.31)%,S期下降为(18.06±1.46)%;细胞凋亡率上升为(13.28±1.65)%;电镜下可见典型的凋亡细胞特征。细胞内Caspase-3, Smac/DIABLO的mRNA、蛋白表达有所上升。结论 Livin靶向RNA干扰通过上调Caspase-3, Smac/DIABLO表达有效地抑制MDA-MB-231细胞增殖,促进凋亡。 Objective To investigate the effect of Livin targeting RNA interference on MDA-MB-231 cell proliferation and apoptosis, and to explore its possible mechanism. Methods Three siRNA targeting Livin siRNA eukaryotic expression vectors were constructed and transfected into breast cancer cells MDA-MB-231 respectively. The expression of Livin, Caspase-3 and Smac / DIABLO at mRNA and protein levels. MTT assay was used to detect the inhibitory effect on cell proliferation. Cell cycle was measured by flow cytometry. Apoptosis was detected by TUNEL assay and cell morphological changes were observed. Results Three specific siRNA expression vectors targeting Livin gene were successfully constructed. They inhibited the expression of Livin gene in MDA-MB-231 cells to varying degrees, and the inhibition rate of si-Livin2 was the highest. The inhibitory rates of Livin mRNA and protein were 76.4% and 70.2% respectively. After 48 h of si-Livin2 transfection, the cell proliferation activity was inhibited compared with untransfected cells, and the inhibition rate reached 36.1% 48 h after transfection. (71.75 ± 1.31)% in G0 / G1 phase and (18.06 ± 1.46)% in S phase, and the apoptotic rate increased to (13.28 ± 1.65)%. The typical apoptotic cells feature. Intracellular Caspase-3, Smac / DIABLO mRNA, protein expression increased. Conclusions Livin targeting RNA interference can effectively inhibit the proliferation and promote the apoptosis of MDA-MB-231 cells by up-regulating the expressions of Caspase-3 and Smac / DIABLO.