中文摘要：

目的siRNA靶向沉默p53蛋白后，观察其对PCNA泛素化修饰及细胞凋亡的影响。方法将p53siRNA及阴性对照siRNA通过脂质体分别转染入HeLa细胞中；转染后48h，顺铂处理不同细胞系，Westernblot法检测p53低表达对细胞PCNA泛素化修饰（ubi-PCNA）及凋亡诱导基因Caspase-3的影响。结果siRNA可显著抑制p53的表达；Westernblot结果提示，与对照组比较，顺铂损伤后p53低表达细胞系其PCNA泛素化修饰蛋白表达增加，同时Caspase-3蛋白表达下降，细胞存活率升高。结论靶向沉默p53的表达，可促进顺铂损伤诱导的PCNA泛素化修饰，降低细胞凋亡率。

英文摘要：

Objective To investigate the effects of silencing p53 protein on the expression of ubiquitinated PCNA and cell apoptosis with RNA interference assay. Methods p53 siRNA and control sequence were transfected into HeLa cells. Then the cells were treated with DNA damaging agent cisplatin. The expressions of ubiquitinated PCNA and Caspase-3 were detected by Western blot. Results p53 siRNA sequence was successfully transfected into HeLa cells. The expression of ubiquitinated PCNA were increased significantly in siRNA interference cells when treated with cisplatin, yet the expression of Caspase-3 protein decreased. Conclusion p53 deficiency may stimulate the expression of ubiquitinated PCNA, thereby reducing the cell apoptosis treated with cisplatin.