二甲双胍影响人结直肠癌细胞增殖和凋亡的机制研究

目的 探讨二甲双胍对人结直肠癌细胞增殖、凋亡的影响及其作用机制.方法 二甲双胍处理体外常规培养人结直肠癌细胞HCT-15、COLO205,通过MTT检测结直肠癌细胞的生长活力;流式细胞仪检测细胞的周期及凋亡;Western blot检测凋亡相关蛋白Bad、Bcl-2、Cleaved caspase-3及信号通路蛋白Akt、p-Akt、mTOR、p-mTOR、S6K、p-S6K的表达变化.结果 不同浓度的二甲双胍作用HCT-15、COLO205细胞72 h后细胞活力明显受到抑制,并呈现浓度依赖性;经流式细胞术分析,二甲双胍能够促使细胞停滞于G0/G1期,同时上调细胞早期及晚期凋亡所占比率;Western blot分析发现,Bad、cleaved caspase-3表达量随着二甲双胍浓度的升高而上调,Bcl-2表达量随着二甲双胍浓度升高而下降;同时,p-Akt及p-mTOR、p-S6K的表达量均明显被抑制,但Akt、mTOR、S6K总蛋白表达量无明显变化.结论 二甲双胍能够抑制结直肠癌细胞增殖,促进细胞凋亡;而具体机制可能与抑制Akt及mTOR通路活性有关.

Mechanism of metformin on the cell proliferation and apoptosis of human colorectal cancer cells

Objective To study the effect of metformin on cell proliferation and apoptosis of human colorectal cancer and to explore the potential mechanism. Methods Human colorectal cancer cell HCT-15 and COLO205 were cultured and treated with metformin in vitro. The cell viability was assessed by MTT assay, and the cell cycle and apopto-sis were tested by flow cytometry. Western blot assay was performed to analyze the changed expression of apoptosis-re-lated proteins (Bad, Bcl-2, cleaved caspase-3), Akt, p-Akt, mTOR, p-mTOR, S6K, p-S6K. Results MTT assay showed metformin could significantly inhibit cell proliferation of HCT-15 cells and COLO205 cells in a dose-dependent manner after 72 h. Meanwhile, metformin could induce G0/G1 arrest, and increase the rate of apoptosis cell. The results of Western blot showed that the expression of Bad and cleaved caspase-3 were significantly increased by metformin treatment, and the expression of Bcl-2 was significantly decreased. Furthermore, the phosphorylation of AKT, mTOR and S6K (p-Akt, p-mTOR, p-S6K) were significantly inhibited, but the total protein expression of AKT, mTOR and S6K were not significantly changed. Conclusion Metformin could inhibit the proliferation of human colorectal cancer cell, and induce the apoptosis via inhibiting the activity of Akt and mTOR.