启动子DNA甲基化调节胃癌中PDX1基因表达  

DNA methylation of the promoter regulating PDX1 gene expression in gastric cancer

作　　者：马娟[1] 廖山婴[1] 王蓓蓓[1] 沙卫红[1] 王启仪[1] 刘庆华[2] 

机构地区：[1]广东省人民医院//广东省医学科学院消化科,广东广州510080 [2]中山大学附属第一医院肾内科,广东广州510080

出　　处：《解剖学研究》2013年第6期422-426,共5页Anatomy Research

基　　金：国家自然科学基金(81001112);广州市科技局珠江科技新星项目(2012J2200019)

摘　　要：目的明确PDX1启动子DNA甲基化,探讨启动子甲基化对PDX1在胃癌中表达的调节作用。方法收集3例胃癌活检组织,免疫组化检测PDX1蛋白表达;吉西他滨处理3株胃癌细胞,RT-PCR检测不同药物剂量和作用时间下PDX1mRNA表达;构建PDX1报告基因,检测启动子活性及吉西他滨处理前后启动子活性的变化;甲基化特异性PCR(MSP)检测3株胃癌细胞和8对配对胃癌组织中PDX1启动子甲基化状态。结果免疫组化结果显示胃癌中PDX1表达低于正常胃黏膜;RT-PCR显示吉西他滨使PDX1 mRNA重获表达,且随剂量和时间依赖性。F383有最强启动子活性,吉西他滨显著增加了PDX1启动子活性(P<0.05)。F383在AGS、BCG823、SGC7901中呈DNA完全甲基化状态;87.5%的胃癌组织出现F383部分甲基化,12.5%出现完全甲基化,癌旁正常组织仅有37.5%出现F383部分甲基化,未出现完全甲基化,两者比较有显著性差异(P<0.05)。结论PDX1启动子存在DNA高甲基化,抑制了胃癌中PDX1的表达。Objective This study aims to determine the regulation of promoter＇s DNA methylation for PDX1 expression in gastric cancer. Methods Gastric cancerous tissues were used for PDX1 protein expression by immunochemistry. Three gastric cancer cell lines were used for PDX1 mRNA expression with or without 5＇-aza-2＇-deoxycytidine （5＇-aza-dC） treatment by RT- PCR. PDX1 reporters constructed were used for detection of PDX1 promoter activity with and without 5＇-aza-dC treatment. The three gastric cancer cells and 8 pairs of gastric cancer tissues were also used for identification of promoter hypermethylation by methylation-specific PCR. Results PDX1 protein was positive in normal gastric mucosa and weakly in cancer tissues. PDX1 expression was up-regulated after 5＇-aza-dC treatment in AGS,BCG823 and SGC7901 ceils, with dose dependency and time dependency. F383 was indentified with the strongest promoter activity, significantly increased by 5＇-aza-dC （P〈O.05）. Total hypermethylation of F383 was found in three cancer cell lines.Promoter methylation of caner tissues was higher than that of paired normal tissues （P〈0.05）. Conclusion DNA hypermenthylation in the promoter inhibits PDX1 expression in gastric cancer.

关 键 词：胰十二指肠同源异型基因1 胃癌 启动子活性 DNA甲基化 

分 类 号：R735.2[医药卫生—肿瘤]