熊果酸诱导人结肠癌细胞HT29凋亡机制的研究

Mechanism of Apoptosis Induced by Ursolic Acid in Human Colon Carcinoma HT29 Cells

目的探讨熊果酸（ursolicacid，uA）对人结肠癌细胞系HT29增殖凋亡的作用及机制。方法采用MTF和双染实验检测uA对HT29细胞的增殖和凋亡；流式细胞术（FCM）检测UA对细胞周期和细胞凋亡率的影响；Western blot（WB）法检测uA作用后HT29细胞内cyt—c、caspase-3及Livin蛋白表达水平的变化。结果UA对HT29细胞的增殖抑制作用呈明显的浓度和时间依赖性。荧光显微镜观察UA作用后细胞呈凋亡特征改变。FCM检测发现，UA可将HT29细胞阻滞于G1期，随着UA浓度的增加，细胞凋亡率和凋亡峰值逐渐增高。WB结果显示随着UA浓度的增加，Livin蛋白和caspase-3酶原的表达逐渐下降，而caspase-3活性片段及cyt—c的表达逐渐升高。结论UA对人结肠癌细胞系HT29有较强的抑制增殖和诱导凋亡作用，其作用机制与激活线粒体凋亡途径及下调凋亡抑制蛋白Livin的表达有关。

Objective To investigate mechanism of apoptosis induced by ursolic acid in human colon carcinoma HT29 cells. Methods The inhibitory effects of UA on proliferation and apoptosis of HT29 were evaluated by MTT and double dye experiment. Effects of UA on cell cycle and apoptosis rate were detected by flow cytometry （FCM）. The expressions of cyt - c, caspase - 3 and Livin were assessed by Western blot （WB） after exposure to UA. Results UA inhibited HT29 proliferation in a time - and dose - dependent manner. Apoptosis characteristics changed after exposure to UA by fluorescence microscope after treated with UA. UA could block HT29 cycle in G1 phase by FCM analy- sis. Apoptosis rate and peak value raised gradually with increasing concentration of UA. The expression of Livin and caspase - 3 decreased, active fragments of caspase - 3 as well as expression of cyt - c increased gradually with increasing concentration of UA. Conclusion UA can inhibit the proliferation and induce apoptosis of HT29, the mechanisms of which are associated with activating apoptosis pathway of mitochondria and reduce the expression of Livin.