中文摘要：

目的探讨胃癌细胞中抑癌基因PTEN5’启动子区CpG岛甲基化状态与其蛋白表达的关系。方法采用甲基化特异性聚合酶链反应（MSP）方法检测不同分化程度的胃癌细胞（HGC-27，MGC-803，BGC-823，SGC-7901）中PTEN基因启动子区域甲基化状态。并通过Western blot法检测该4种细胞中PTEN蛋白的表达。结果除SGC-7901外，其他三种胃癌细胞PTEN基因都有不同程度的甲基化，并随着胃癌细胞分化程度的降低。PTEN启动子区甲基化逐渐增强（P〈0．01）；PTEN蛋白表达逐渐减弱（P〈0．01）。PTEN蛋白表达与其启动子区高甲基化之间呈负相关。结论PTEN基因启动子区异常甲基化可能导致该基因失活，使其蛋白表达减少甚至缺失，这可能是导致胃癌发生、发展的重要机制之一。

英文摘要：

Objective： To investigate the relationship between methylation status of 5＇ CpG island located in the promoter region of PTEN gene in gastric cancer cells and its protein expression. Methods： Methylation status of PTEN gene in different differentiation gastric cancer cell lines （HGC-27, MGC-803, BGC-823, SGC-7901） and their proteins expression were detected by methylation-specific PCR （MSP） and Western blot technique. Results： All cells except for SGC-7901 had different level of hypermethylation of PTEN gene, and hypermethylation of PTEN became stronger （P〈0. 01） and protein expression became weaken gradually with differentiation decreaseing （P〈0. 01）. PTEN protein expression and hypermethylation in its promoter region negatively correlated. Conclusions： Hypermethylation can inactivate PTEN and reduce its protein expression. It may be a mechanism which leads to oncogenesis, metastasis of gastric carcinoma.