非小细胞肺癌中hMLH1启动子的甲基化

Methylation of Promoter for hMLH1 in Non-small Cell Lung Cancer

目的探讨在非小细胞肺癌(NSCLC)中DNA修复基因hMLH1启动子甲基化与基因转录失活的关系,观察5-Aza-CdR的干预作用。方法甲基化特异的PCR(methyl-specificPCR,MSP)和RT-PCR法分别测定基因的甲基化率和转录水平。结果NSCLC癌/癌旁组织中的甲基化率分别是hM-LH1为55%和14%;>65岁组hMLH1甲基化率明显高于≤65岁组(P<0.01),hMLH1甲基化率随吸烟指数增高而升高(P<0.05或P<0.01);hMLH1的甲基化率随TNM临床分期进展而逐渐增加(P<0.05或P<0.01)。甲基化的NSCLC标本hMLH1基因mRNA转录下降或失活,在细胞株水平5-Aza-CdR处理后hMLH1恢复转录活性。结论启动子甲基化是调节hMLH1转录活性的重要机制,5-Aza-CDR具有逆转甲基化而恢复转录的作用。

Objective To understand the role of promoter methylation for hMLH1 in non-small cell lung cancer. Methods The methylation status was determined by MSP（methyl-specific PCR）, and RT-PCR was employed to measure mRNA level. Results The frequencies of methylation in NSCLC and corresponding non-neoplastic lung tissues were.. 55% and 14% for hMLH1. Methylation of hMLH1 was more frequent in %65 group（P〈0. 01）. Methylation of hMLH1 was more frequent in smoking group（（P〈 0. 05 or P〈0. 01）. Methylation of hMLH1 was more frequent with TNM stage advanced（P〈0. 05 or P 〈0. 01）. The samples with methylated status showed the decline or loss of hMLH1 mRNA transcription. 5-Aza-CdR could induce re-expression of the silenced methylated hMLH1. Conclusion Promoter methylation is the predominant mechanism in hMLH1 deregulation in NSCLC, but 5-Aza-CdR could reverse the gene transcriptional activity.