人参皂甙20(R)-Rg3对人胶质瘤U87细胞凋亡的影响

Effects of 20(R)-Ginsenoside Rg3on Apoptosis of Human Glioma U87 Cells

目的探讨人参皂甙20(R)-Rg3对人胶质瘤U87细胞凋亡作用的影响。方法应用MTT法及流式细胞术观察不同浓度的Rg3对U87细胞凋亡的影响,采用细胞吖啶橙/溴乙锭荧光观察凋亡形态学改变,采用Western Blot技术检测细胞Bcl-2、Bax、p-Akt及t-Akt蛋白表达。结果 Rg3显著抑制U87细胞增殖,Rg3呈剂量依赖性诱导肿瘤细胞凋亡。不同浓度Rg3作用U87细胞24h,U87细胞中Bax表达逐渐增高,Bcl-2表达降低,Bax/Bcl-2呈浓度依赖性升高,细胞p-Akt蛋白表达降低,而t-Akt蛋白未见改变。结论 Rg3通过抑制PI3K/Akt信号转导通路中的Akt磷酸化,影响胶质瘤U87细胞系Bcl-2蛋白表达降低,促凋亡Bax蛋白表达增加,调控胶质瘤细胞的凋亡。

Objective To examine the effects of 20（R）-ginsenoside Rg3 on apoptosis of human glioma U87 cells. Methods The cytotoxic effect of Rg3 on human glioma U87 ceils was determined with varying concentration of Rg3 by MTT assay and flow-cytometric analysis. Morphological characteristics of apoptosis was measured by acridine organe/ethidium bromide assays. Alterations in signaling events were determined with Western Blot analysis probing for Bcl-2,Bax, p-Akt and t-Akt. Results Using the human glioma U87 cell line, Rg3 treatment resulted in dose-dependent and time-dependent inhibition of cellular proliferation and the Rg3 treatment resulted in induction of apoptosis in dose-dependent manner. As shown by PI and annexin V method, we found that Rg3 caused a dosage dependent increase in U87 cell apoptosis. As shown by immunoblot analysis, Rg3 could cause the down- regulation of p-Akt protein expression without an effect on total t-Akt expression and also result in a dose-dependent decrease in antiapoptotic Bcl-2 and a concomitant increase in proapoptic Bax proteins. The ratio of Bax/Bcl 2 was significantly increased in a dose-dependent manner with Rg3 treatment. Conclusion The study suggests that Rg3 causes an inhibition of phosphatidylinositol 3-kinase/Akt activation that, in turn, results in modulatons in Bcl-2 family proteins in sueh a way that the apoptosis of U87 cells are regulated.