高表达p21增加5-Fu对胃癌细胞的杀伤作用及机制

High expression of p21 increases killing effect of 5-Fu on gastric cancer cells

目的:p21是一种重要的细胞周期负性调控因子,目前其在胃癌化疗中的作用上不清楚.本课题主要观察p21蛋白转染胃癌细胞后,研究其对5-氟尿嘧啶(5-fluorouracil,5-Fu)作用于胃癌细胞的敏感性影响及其可能的作用机制.方法:采用脂质体转染技术改变人胃癌细胞BGC823、SGC7901中p21蛋白变化,应用免疫印迹鉴定p21蛋白表达;CCK8比色法检测p21蛋白转染后BGC823、SGC7901细胞株对5-Fu敏感性的变化;采用流式细胞术分析细胞周期分布.结果:将p21质粒转染胃癌细胞后,细胞中p21蛋白表达量明显增高,与空载对照组比较具有统计学意义(P<0.05).p21高表达的胃癌细胞株对5-Fu敏感性明显增强,与空载对照组、阴性对照组比较,均具有统计学意义(P<0.01).p21高表达的细胞株处于G0/G1期比例明显增加,而S、G2/M期细胞比例明显减少;计算出细胞增殖指数(proliferation index,pI),与空载对照组、阴性对照组比较,均具有统计学意义(P<0.01).同时p21下游的周期蛋白依赖性激酶蛋白CDK2、Cyclin E均明显降低,与空载对照组、阴性对照组比较,均具有统计学意义(P<0.01).结论:p21蛋白能增加胃癌细胞珠对5-Fu的敏感性,其作用可能是通过使细胞周期发生G0/G1期阻滞及下调CDK2、Cyclin E的表达来实现的.

AIM： To investigate the effect of p21 expression on the sensitivity of gastric cancer cells to 5-fluo- rouracil （5-Fu） and the possible mechanisms in- volved. METHODS： A p21 expression plasmid was transfected into two gastric cancer cell lines, BGC803 and SGC7901, using liposomes, and Western blot was used to detect the expression of p21. After transfection, the CCK8 colorimet-ric method was used to detect the proliferation of the two gastric cancer cell lines treated with 5-Fu. Flow cytometry was used to test the change of the cell cycle. RESULTS： After transfection, p21 expression was significantly up-regulated in the SGC7901 and BGC803 cells compared with control cells （P 〈 0.05）. The cells with p21 overexpression were highly sensitive to 5-Fu （P 〈 0.05）. Cell cycle analysis showed that the cells with p21 overexpression had a significantly increased G0/G1 population （P 〈 0.01）. Western blot assay showed down-regulation of expression of CDK2 and Cyclin E （P 〈 0.01）. CONCLUSION： Overexpression of p21 protein increases the sensitivity of gastric cancer cells to 5-Fu, possibly via mechanisms associated with inducing G0/G1 arrest and down-regulation of CDK2 and Cyclin E expression.