反义survivin-脂质体复合物对肝癌细胞生长凋亡和细胞周期的影响

The effect of antisense survivin-liposome complex on cell growth, apoptosis and cell cycle in hepatocellular carcinoma cells

目的探讨反义survivin-脂质体复合物(survivin-ASODN)对肝癌细胞系HepG2的生长抑制作用及其机制,为肝癌及survivin阳性肿瘤的治疗提供理论依据。方法用脂质体介导survivin-ASODN转染肝癌细胞系HepG2细胞;通过RT-PCR和Westernblot检测survivin表达水平;以MTT法测量细胞生长情况;以流式细胞术测定caspase-3活性及凋亡率,电镜观察细胞形态学变化,并应用流式细胞仪同步分析survivin-ASODN对肝癌细胞系HepG2增殖周期的影响。结果surviving-ASODN可有效下调survivin表达水平,并呈剂量依赖关系,其IC50值为250nmol/L,最大效应浓度为600nmol/L;可抑制细胞生长,激活caspase-3活性,诱导细胞凋亡,使其出现凋亡形态学变化,如胞浆空泡变性、核浓缩和核碎裂。细胞周期的同步分析显示,surviving-ASODN对HepG2细胞增殖周期有明显影响,HepG2先出现细胞周期阻滞,紧接着出现细胞凋亡;低浓度处理后,可将细胞先后阻滞在S期和G2/M期;高浓度时,S期阻滞被加强,可快速诱导细胞凋亡,并且,细胞凋亡率随着药物浓度的增加和作用时间的延长明显上升。结论surviving-ASODN对肝癌细胞有强的生长抑制效应,其机制是与阻断细胞周期及诱导细胞凋亡有关。

Objective To investigate the effects and the mechanisms of cell growth inhibition in hepatocellular carcinoma cells after induction with antisense survivin-liposome （LIP） complex, and to provide evidence in treatment for hepatocellular carcinoma and tumors expressing survivin. Methods Survivin ODNs was transfected into HepG2 cells mediated by LiP reagent. The expression of survivin mRNA and protein was detected by RT-PCR and Western blot. MTr assay was applied to determine cell proliferation in HepG2 cells. Active caspase-3 and apoptosis rate were evaluated by flow cytometric analysis. The morphological changes were assessed by electron microscopy. Cell cycle was analyzed by flow cytometry in the cell cycle - synchronized hepatocellular carcinoma cells treated with the antisense compound. Results Antisense compound efficiently down-regulated survivin expression （ mRNA and protein） in a dose-dependent manner with an IC50 of 250 nmol/L. Its maximal effect was achieved at a concentration of 600 nmol/L, when expression levels were down-regulated by 80%, as revealed by gradually increase of caspase-3-like protease activity and apoptosis rate in a time-dependent manner. Morphological apoptotic changes such as membrane blebbing, loss of microvilli, cytoplasmic vacualization, condensation of cytoplasm and nucleus, chromatin fragmentation, and apoptosis and cell growth inhibition were observed. In the cell cycle-synchronized hepatocellular carcinoma cells, antisense compound induced cell cycle arrest followed by apoptosis. After treated with low concentration of compound, the cell cycle was arrested at S phase or G2/M phase ; while at high concentration, the cell cycle was mainly arrested at S phase. Apoptosis was obviously observed and the rate of apoptosis was increased in a time and concentration-dependent manner. Conclusion Antisense survivin has significant inhibitory effect on growth of hepatocellular carcinoma cells in vitro. This is associated with cell cycle arrest and apoptosis.