PTCH1基因甲基化在胃癌发病中的作用

Role of PTCH1 gene hypermethylation in tumorigenesis of gastric cancer

目的:探讨PTCH1基因甲基化在胃癌发生中的作用及去甲基化试剂5-氮杂-2′-脱氧胞苷(5-Aza-dC)对胃癌的治疗作用。方法:选取10例胃癌组织及其癌旁正常组织和胃癌细胞株AGS,抽提组织和细胞的总RNA和基因组DNA。实时定量QRT-PCR检测PTCH1基因的mRNA表达,MSP(methylation specific PCR)分析PTCH1基因启动子区甲基化变化。用5-Aza-dC处理AGS细胞株,流式细胞术检测细胞周期和凋亡并观察PTCH1基因甲基化水平的改变。结果:胃癌组织、癌旁正常组织和胃癌细胞株AGS中PTCH1基因表达和启动子甲基化水平呈负相关,相关系数为-0.591(P=0.006);5-Aza-dC的处理可引起胃癌细胞AGS细胞发生凋亡和G0/G1期阻滞,PTCH1基因发生去甲基化变化并表达增加。结论:PTCH1基因启动子区高甲基化是胃癌细胞PTCH1低表达主要原因之一,5-Aza-dC能逆转PTCH1基因甲基化状态,调控其表达,对胃癌具有一定的治疗作用。

Objective：To study the effect of PTCH1 methylation on gastric carcinogenesis and the therapeutic effect of methylation inhibitor,5-aza-2′-deoxyeytidine （5-aza-dC）, for treatment of gastric cancer.Methods： The total RNAs were extracted from 10 gastric cancer tissues,their corresponding adjacent normal tissues, and gastric cancer cell line AGS.The PTCH1 mRNA expression was detected by Quantitative real-time PCR （QRT-PCR） and the methylation of the promoter was examined by methylation specific PCR （MSP）.AGS cells were treated by 5-Aza-dC; the cell cycle and apoptosis were examined by flow cytometry,and the methylation level was also observed.Results： PTCH1 expression was negatively correlated with promoter methylation in gastric cancer tissues,their corresponding adjacent normal tissues, and gastric cancer cell line AGS（r=-0.591,P=0.006）.5-Aza-dC treatment caused apoptosis and G0/G1 phase arrest of AGS cells,and also induced demethylation of PTCH1 and increased its expression.Conclusion： Hypermethylation of PTCH1 gene promoter region is one of the main causes of low PTCH1 expression in AGS cells.Demethylation agent 5-Aza-dC can reverse this methylation status of PTCH1 and regulate the expression of PTCH1,suggesting a role for it in gastric cancer treatment.