胃癌中多基因甲基化状态及其表达的研究

Detection of multiple gene methylation and expression in gastric carcinoma

目的了解胃癌中p16、E-cadherin、Runx3、DAPK和CHFR基因启动子CpG岛的甲基化状态,并探讨基因异常甲基化与mRNA表达的关系及其意义。方法采用甲基化特异性PCR(MSP)技术检测12例胃癌患者癌组织及其相应的癌旁正常组织中5种基因的甲基化状态,以12例胃镜活检的正常胃组织作为对照,采用RT-PCR方法相应检测了5种基因的mRNA表达水平。并分析每种基因甲基化程度与表达水平之间的关系。结果胃癌组织中,p16、E-cadherin、Runx3、DAPK和CHFR基因的甲基化率分别为41.7%、8.3%、58.3%、33.3%和58.3%,相应的癌旁正常组织中,p16、E-cadherin、Runx3、DAPK和CHFR基因的甲基化率分别为8.3%、0.0%、8.3%、8.3%和16.7%,且75%的胃癌组织中至少有一种基因甲基化,显著高于癌旁正常组织25%(P<0.05),而健康对照组织中无基因甲基化,在甲基化的胃癌组织中均无p16、E-cadherin和DAPKmRNA表达,而癌旁正常组织、非甲基化的癌组织中均有其表达。结论胃癌中多基因启动子CpG岛高甲基化是一个频繁的事件,并且基因启动子高甲基化与其mRNA表达缺失有关,这可能参与了胃癌的发生发展。

Objective To study the promoter hypermethylation status of p16,E-cadherin,Runx3,DAPK and CHFR genes in gastric carcinoma and its impact on the mRNA expression.Methods Methylation-specific polymerase chain reaction（MSP）was used to detect promoter methylation status of the p16,E-cadherin,Runx3,DAPK and CHFR genes in tumor tissues,corresponding adjacent normal tissues and of 12 patients with gastric carcinoma,and normal gastric biopsy samples of 12 healthy people was also collected as control.The mRNA expressions were investigated by RT-PCR.Results Nomal gastric cancinoma has no genes methylation.The methylation rates of p16,E-cadherin,Runx3,DAPK and CHFR were 41.7%,8.3%,58.3%,33.3% and 58.3%,respectively,in gastric cancer tissues and 8.3%,0.0%,8.3%,8.3% and 16.7%,respectively,in adjacent normal tissues.Methylation of one or more of the genes was found in the tissue of 75% gastric cancer,which was significantly higher than that in adjacent normal tissue（25%,P〈0.05）.In contrast,no aberrant methylation was found in normal gastric biopsy samples of 12 healthy people.None of p16,E-cadherin and DAPK mRNA was expressed in all the gastric cancer tissues with gene promoter having hypermethylation,whereas it was expressed in adjacent normal tissues and gastric cancer tissues without hypermethylation.Conclusion Multiple gene methylation is a frequent event during gastric cancer progression,and may be a predominant cause of down-regulation or loss of the gene expression.