中文摘要：

目的：观察5-氮杂脱氧胞苷酸（5-Aza-dC）对ERα、ERβ阴性细胞株MDA-MB-435的ERα、ERβ的恢复表达作用。方法：采用不同终浓度（1、2.5、5、10、20μmol/L）5-Aza-dC处理ERα、ERβ阴性细胞株MDA-MB-435 96h,通过逆转录PCR（Reverse transcript PCR,RT-PCR）方法检测5＇-Aza-dC处理后ER阴性MDA-MB-435乳腺癌细胞株DNMT1、ERα、ERβmRNA变化情况。结果：不同浓度5-Aza-dC均可明显抑制DNMT1 mRNA表达,20μmol/L的5-Aza-dC对DNMT1 mRNA抑制作用最为明显;采用不同浓度5-Aza-dC处理MDA-MB-435细胞96h后,ERα、ERβmRNA表达水平随5-Aza-dC浓度增大而增加,差别具有显著性（P〈0.05）。结论：DNMT抑制剂5-Aza-dC可以浓度依赖性地恢复ER阴性细胞中ERα,ERβmRNA表达,说明ERα,ERβ基因启动子甲基化是引起ERα、ERβ蛋白失表达的重要机制之一。

英文摘要：

Objective：To investigate the effect of 5-Aza-2＇-deoxycytidine inducing ERα,ERβ re-expression in ERα,ERβ negative MDA-MB-435 breast cancer cell line.Methods：The level of DNMT1,ERα and ERβ mRNA in ERα,ERβ negative MDA-MB-435 breast cancer cell line before or after treated with 5-Aza-dC were tested by RT-PCR.Results： Compared with vehical group,cells treated with different concentration of 5-Aza-dC（1,2.5,5,10,20μmol/L） DNMT1 mRNA expression decreased.After been exposed to 2.5,5,10,20μmol/L 5-Aza-dC respectively ERα,ERβ mRNA expression were resorted in a dose dependent manner,there was statistically diffrence（P〈0.05）.Conclusion： The expression of ERα,ERβ mRNA in ERα,ERβ negative breast cancer cell line coud be resorted by 5-Aza-dC in a dose dependent manner.So,aberrant methylation was one of the main mechanisms of inducing the loss of ERα,ERβ expression.