关键词: 食管癌, MGMT, 甲基化, 循环DNA

Abstract: BACKGROUND AND AIM:To analyze whether promoter methylation of O6-methylguanine-DNA methyltransferase (MGMT) gene is associated with the risk for esophageal squamous cell carcinoma(ESCC), and to evaluate the clinical significance in the screening and early diagnosis of ESCC. MATERIALS AND METHODS: 91 patients with newly diagnosed, untreated esophageal cancer were recruited in the present study. Esophageal cancer tissues, tissues adjacent to the tumors and peripheral blood were collected to determine CpG island hypermethylation of the promoter. Methylation specific PCR(MSP) was used to examine the methylation status of MGMT gene, total mRNA was extracted from esophageal cancer tissues and tissues adjacent to the tumors, expression levels of MGMT gene were measured by quantitative real-time reverse transcription-PCR. RESULTS:The risk for ESCC showed significant correlation to promoter hypermethylation of MGMT gene (OR=7.750, 95％CI=2.736～21.955). There was no significant correlation between methylation status and mRNA level. Hypermethylation of MGMT gene in plasma from ESCC patients was significantly correlated to that in tumor tissue(P<0.01). The detection rate of CpG island hypermethylation of MGMT promoter in plasma was moderately correlated with that in tumor tissue(Kappa=0.603, P<0.01). CONCLUSION: This study suggested that CpG island hyper- methylation of MGMT gene was associated with an enhanced risk for ESCC. Detection of the aberrant methylation in the promoter of MGMT gene from ESCC patient plasma might provide valuable information for the screening and early diagnosis of ESCC.

Key words: esophageal cancer, O6-methylguanine-DNA methyltransferase;methylation;circulating DNA