熊果酸诱导胃癌细胞BGC-823凋亡机制的研究

目的:探讨熊果酸(UA)对胃癌细胞BGC-823增殖抑制和诱导凋亡的作用机制。方法:采用MTT法检测UA对BGC-823细胞的增殖抑制效应;用琼脂糖凝胶电泳观察DNA凋亡片段;流式细胞仪检测UA作用后BGC-823细胞的周期分布和凋亡率;用Fas单克隆抗体检测BGC-823细胞表面Fas的表达;Western blot检测BGC-823细胞Bcl-2的表达及caspase-3和caspase-8的活性。结果:UA对BGC-823细胞具有增殖抑制效应,并呈浓度和时间依赖性。UA作用24 h时半数抑制浓度(IC50)为43.10μmol/L。当UA浓度为50和60μmol/L时,琼脂糖凝胶电泳可呈现DNA凋亡梯带。随着UA浓度从20μmol/L递增到60μmol/L,周期检测发现BGC-823细胞出现亚G1峰逐步增高,S期阻滞增加,G1期下降。细胞内Bcl-2表达下降,caspase-3和caspase-8活性增加。BGC-823细胞表面未发现Fas的表达。结论:UA对BGC-823细胞有较强的增殖抑制和诱导凋亡作用,下调Bcl-2的表达及激活caspase-3、caspase-8可能是其诱导凋亡的机制。

Mechanism of Apoptosis Induced by Ursolic Acid in Gastric Carcinoma BGC-823 Cells

Objective: To investigate ursolic acid(UA) proliferation inhibiting and apoptosis inducing effect on human gastric carcinoma cell line BGC-823.Methods: Cell proliferation inhibition was detected by MTT assay.DNA fragmentation was determined by DNA electrophoresis.Cell cycle and apoptosis rate were analyzed by flow cytometry(FCM).Fas antigen expression on BGC-823 cell surface was detected with Fas monoclonal antibody and then analyzed by FCM.The expression of Bcl-2 and activity of caspase-8 and -3 were detected by Western blot.Results: UA can inhibit proliferation of BGC-823 cells effectively in a dose- and time-dependent manner.After BGC-823 was treated by UA for 24 h,the IC_(50) value was 43.10 μmol/L.When UA concentration was 50 or 60 μmol/L,DNA ladder of apoptosis was observed by gel electrophoresis.While UA concentration was increased from 20 μmol/L to 60 μmol/L,cells in sub-G_(1) phase and S-phase were increased in cell cycle,but decreased in G_(1)-phase.UA decreased Bcl-2 protein levels and increased the activation of caspase-3 and caspase-8.The Fas expression on BGC-823 cells was not found.(Conclusion:) UA has inhibitory and apoptosis inducing effects on BGC-823 cells.Down-regulation of the expression of Bcl-2 and induction of activation of caspase-8 and -3 may contribute to its apoptosis effects.