目的：研究5氮杂2′脱氧胞苷(5AzaCdR)在卵巢癌细胞系SKOV3中对核苷酸切除交叉修复互补基因1（excision repair cross complementation group 1, ERCC1）表达的影响及可能的机制。方法：设计特异性针对DNA甲基转移酶1(DNA methyltransferase 1, DNMT1)基因的shRNA转染入人卵巢癌细胞系SKOV3细胞中，Western blotting检测SKOV3细胞DNMT1以及ERCC1的表达变化；利用不同浓度5AzaCdR于不同时间点处理卵巢癌SKOV3细胞，Western blotting检测DNMT1和ERCC1蛋白在处理前后的变化，利用亚硫酸氢钠法检测ERCC1基因启动子区域甲基化水平。结果：0.5、1.0、2.0、4.0 μmol/L的5AzaCdR作用于SKOV3细胞后，DNMT1表达水平呈浓度依赖性降低，而ERCC1表达水平呈浓度依赖性升高；使用终浓度为1.0 μmol/L的5AzaCdR处理SKOV3细胞12、24、36 h后，DNMT1表达水平呈时间依赖性降低，而ERCC1表达水平呈时间依赖性升高，亚硫酸氢钠法检测示药物处理前ERCC1启动子区域处于高甲基化水平，在用1.0 μmol/L的5AzaCdR处理后，其启动子发生了去甲基化。结论：5AzaCdR通过DNMT1调控卵巢癌SKOV3细胞中ERCC1基因的甲基化及其表达水平。

Objective:Objective: To investigate the effects of 5AzaCdR on expression of excision repair cross complementation group 1 (ERCC1) in ovarian cancer cell line SKOV3 and its possible mechanism.Methods: shRNA that specifically targeting DNA methyltransferase 1 (DNMT1) was constructed and transfected into SKOV3 cells. Western blotting was applied to determine the expressions of DNMT1 and ERCC1 in SKOV3 cells; Ovarian cancer cell line SKOV3 was treated with 5AzaCdR of various concentrations for different time courses, and Western blotting was used to determine the protein changes of DNMT1 and ERCC1 before and after the treatment; and the methylation level of ERCC1 promoter was tested by Sodium Bisulfite method. Results: After being treated with 5AzaCdR (at the concentrations of 0.5, 1.0, 20, 4.0 μmol/L), the expression of DNMT1 protein in SKOV3 cells was decreased in a dosedependent manner while the ERCC1 protein was increased in a timedependent manner; With the treatment of 5AzaCdR (concentration of 1.0 μmol/L) for 12, 24 and 36 h, the expression of DNMT1 protein was decreased and the ERCC1 protein was increased in SKOV3 cells, and the expression both changed in a timedependent manner. Sodium Bisulfite method indicated that the methylation of ERCC1 promoter was at high level before the treatment; However, after the treatment of 5AzaCdR at concentration of 1.0 μmol/L, the promoter of ERCC1 showed demethylation．Conclusion: 5AzaCdR regulates the methylation of ERCC1 promoter and its expression in SKOV3 cells via.