Zheng Chang-Qing, Ji Shou-Ping, Gong Feng, Li An-Ming, Tai Jun-Li, Zhang Yang-Pei
Department of Biochemistry and Molecular Biology, Institute of Transfusion Medicine, Academy of Military Medical Sciences, Beijing, 100850, P.R. China.
Ai Zheng. 2009 Jun;28(6):575-80.
Epigenetic silencing of the DNA repair gene, O6-methylguanine-DNA methyltransferase (MGMT), is associated with the therapeutic response to methylating agents. This study was to assess the value of detecting the promoter methylation of MGMT gene in chemotherapy for glioma.
Methylation-specific PCR (MSP) was employed to detect MGMT promoter CpG island methylation in 39 samples of glioma taken from surgery. Western blot and immunohistochemistry were used to detect protein expression. MTT were employed to detect the sensitivity of two glioma cell lines to alkylating agents, ACNU and TMZ. The Kaplan-Meier curve was adopted to estimate the overall survival according to the methylation status of the MGMT promoter.
Methylation of MGMT promoter CpG island was detectable in 46.2% of glioma tissues, but not in any normal tissues. The expression rate of MGMT protein was 61.5%. The status of MGMT methylation status was association with the protein level of MGMT (P<0.05). The MGMT gene was demethylated in glioma cell line SHG-44 following 5-Aza-CdR treatment; the expression of MGMT protein was restored and the resistance of SHG44 cells to alkylating agents was reversed. The overall survival was higher in patients with methylated MGMT promoter than in those with unmethylated MGMT promoter (P<0.05).
The status of MGMT promoter CpG island methylation is closely correlated to MGMT protein expression and sensitivity of cells to alkylating agents in glioma. Detection of the methylated sequences of MGMT may be used as a predictive factor for the treatment of glioma.
DNA修复基因O6-甲基鸟嘌呤-DNA甲基转移酶（MGMT）的表观遗传沉默与对甲基化剂的治疗反应相关。本研究旨在评估检测MGMT基因启动子甲基化在胶质瘤化疗中的价值。
采用甲基化特异性PCR（MSP）检测39例手术切除的胶质瘤样本中MGMT启动子CpG岛甲基化情况。采用蛋白质免疫印迹法和免疫组织化学法检测蛋白表达。采用MTT法检测两种胶质瘤细胞系对烷化剂ACNU和替莫唑胺（TMZ）的敏感性。采用Kaplan-Meier曲线根据MGMT启动子的甲基化状态评估总生存期。
46.2%的胶质瘤组织可检测到MGMT启动子CpG岛甲基化，而正常组织中均未检测到。MGMT蛋白表达率为61.5%。MGMT甲基化状态与MGMT蛋白水平相关（P<0.05）。5-氮杂-2'-脱氧胞苷（5-Aza-CdR）处理后，胶质瘤细胞系SHG-44中MGMT基因去甲基化；MGMT蛋白表达恢复，SHG44细胞对烷化剂的耐药性逆转。MGMT启动子甲基化的患者总生存期高于未甲基化的患者（P<0.05）。
MGMT启动子CpG岛甲基化状态与胶质瘤中MGMT蛋白表达及细胞对烷化剂的敏感性密切相关。检测MGMT甲基化序列可作为胶质瘤治疗的预测指标。
