中文摘要：

采用克隆形成实验检测U0126对A549细胞的放射增敏作用；MTT法检测U0126联合X-射线对A549细胞的增殖抑制作用；流式细胞术检测U0126联合X-射线对A549细胞周期的影响；蛋白免疫印迹杂交法检测p-erk蛋白在A549细胞中的表达；衰老相关8．半乳糖苷酶染色检测A549细胞衰老的变化。结果显示，U0126使p-erk蛋白表达下降，能够增加A549细胞的放射敏感性，放射增敏比为1．18。单纯使用U0126能明显抑制A549细胞的增殖，诱导G1期细胞阻滞并具有时间依赖性和剂量依赖性。U0126联合X-射线也能抑制A549细胞的增殖，增强G1期细胞阻滞现象和细胞衰老现象。以上结果表明，U0126能增加A549细胞的放射敏感性，其作用机制可能与细胞周期阻滞及细胞衰老增强有关。

英文摘要：

The radiosensitizing effects of MEK inhibitor U0126 on A549 ceils were determined by colony forming assay. A549 cells were exposed to X-ray with or without U0126 treatment. MTT assay was used to evaluate the cell viability. Cell cycle distribution was analyzed by flow cytometry. Expression of p-erk protein was confirmed by Western Blot. SA-β-gal assay was used to measure the phenomenon of senescence. The results showed that U0126 could decrease the expression of p-erk protein while enhance the radiosensitivity of A549 ceils, and the SER was 1.18 ERK inhibition significantly suppressed cell viability and induced Gl-phase arrest. After treatment of U0126 combined with X-ray irradiation, the phenomenon of Gl-phase arrest and senescence appeared more obvious. U0126 can enhance the radiosensitivity of A549 cells. The radiosensitizing effects of U0126 on A549 cells may contribute to the increase in phenomenon of Gl-phase arrest and senescence.