中文摘要：

目的探讨在石英刺激的人胚肺成纤维细胞（human embryo lung fibroblasts，HELF）中Ku80蛋白表达的变化及Ku80／p53通路在石英诱导的细胞周期改变中的作用。方法RNAi技术抑制Ku80蛋白表达，流式细胞技术检测细胞周期，免疫印迹技术检测Ku80、p53、p21蛋白的表达及p53-ser15磷酸化水平，并用Image—Proplus 6．0软件对条带光强度进行半定量分析。结果Ku80蛋白表达与石英刺激呈剂量-反应和时间-反应关系；石英刺激阴性对照H—NC细胞，G1期细胞所占比例从89．28％±2．19％下降到68．93％＋3．79％；抑制Ku80蛋白表达的HELF细胞（H—Ku80）的G。期细胞所占比例进一步减少，从85．16％±3．73％下降到59．92％±3．31％，差异均有统计学意义（P〈0．05）；抑制Ku80蛋白表达后，石英引起的p53、p21蛋白及p53-ser15磷酸化水平增高受抑制。结论Ku80对p53、p21蛋白表达及p53-ser15磷酸化水平起调节作用，Ku80／p53通路可能参与了石英诱导的细胞周期改变。

英文摘要：

Objective To study the roles of Ku80/p53 pathway in silica-induced cell cycle changes in human embryo lung fibroblasts （HELF）. Methods Ku80 siRNA expression vectors were transfected into HELF by lipofectamine. Flow cytometry was used to detect the distributions of cell cycle and western blot assay was used to determine the expression level of Ku80, p53 and p21 proteins or the phosphorylation levels of p53- ser15 after cells were exposed to silica. Results The expression levels of Ku80 protein increased in concentration-dependent and time-dependent manners after cells were exposed to silica. The proportion of G1 phases in H-NC cells （controls） decreased from 89.28%±2.19% to 68.93%±3.79% after exposure to silica, and the proportion of Gt phases in HELF cells （H-Ku80） decreased from 85.16%±3.73% to 59.92%±3.31% after exposure to silica （P〈0.05）. The expression levels of Ku80, p53 protecns or p21 proteins or phosphorylation level of p53-ser15 were obviously suppressed in H-Ku80, as compared with H-NC. Conclusion Ku80/p53 pathway plays a role in the cell cycle charges induced by silica in human embryo lung fibroblasts.