脑胶质瘤MGMT、hMLH1和hMSH2基因启动子甲基化状态研究

目的：探讨脑胶质瘤患者O6-甲基鸟嘌呤-DNA甲基转移酶基因MGMT和错配修复基因hMLH1、hMSH2启动子CpG岛甲基化状态,及其在烷化剂化疗中的意义。方法：采用甲基化特异性PCR（MSP）方法检测39例脑胶质瘤和6例正常脑组织MGMT、hMLH1和hMSH2基因启动子区的甲基化状态,免疫组化方法测定蛋白表达。结果：脑胶质瘤患者组织MGMT、hMLH1和hMSH2基因启动子区甲基化发生率分别为46.2%、10.3%和20.5%,3种基因启动子未甲基化模式与其对应蛋白表达模式相似,并与患者性别、年龄、病理类型和病理分级无明显相关性。回顾性分析患者资料,显示39例脑胶质瘤患者中,MGMT基因甲基化的患者生存期显著高于MGMT基因未甲基化患者（P〈0.05,Log-rank检验）。结论：MGMT及错配修复基因甲基化是脑胶质瘤发生过程中常见的分子事件,可能与肿瘤的发生有关;检测MGMT、hMLH1和hMSH2基因启动子甲基化状态,在判断脑胶质瘤患者预后和预测烷化剂化疗耐药性中可能具有重要意义。

Investigation of Aberrantly Methylated Promoter CpG Islands of MGMT,hMLH1 and hMSH2 Genes in Glioblastoma Patients

Objective： To investigate the promoter CpG island methylation status of O6-methylguanine-DNA methyhransferase（MGMT） gene, mismatch repair genes hMLH1, hMSH2 in tumor of glioblastoma and its roles in alkylating agents chemotherapy. Methods： Methylation-specific PCR（MSP） was employed to detect promoter CpG island methylation of the MGMT, hMLH1 as well as hMSH2 genes in 39 surgical tumor tissue samples from glioblastoma patients and 6 normal tissue samples. Results： Promoter CpG island methylation of MGMT, hMLH1 and hMSH2 were detectable in 46.2%, 10.3% and 20.5% of glioblastoma tumor DNA; and in 61.5%, 87.2% and 76.9% of patients tissue three proteins were detected respectively. For the entire population of 39 glioblastoma patients who were enrolled in operating treatment combined with radiotherapy and chemotherapy with alkylating agents, there was a significant difference in overall survival between patients with methylated MGMT promoter and those with an unmethylated MGMT promoter（P〈0.05 by the Log-rank test）. Conclusion： Promoter CpG island methylation may be a frequent event in glioblastoma carcinogenesis. Detection of the methylated sequences of MGMT, hMLH1 and hMSH2 appears to be promising as a predictive factor in primary giloblastoma.