粪便中MGMT，p16INK4A及ECAD基因启动子甲基化检测在结直肠癌诊断中的价值

目的：探讨粪便中p16INK4A、ECAD及MGMT基因启动子甲基化在结直肠癌诊断中的应用价值。方法选择我院老年病科2014年2月至2015年11月收治的65岁以上老年健康者50例(对照组)、结直肠镜检查证实良性结直肠疾病者41例(良性肠病组)和结直肠癌患者46例(肠癌组)为研究对象。采用表观遗传学方法应用甲基化特异PCR对上述患者粪便中p16INK4A、MGMT和ECAD基因启动子DNA甲基化进行检测，判断上述标本中各基因启动子的甲基化水平。根据p16INK4A、MGMT和ECAD基因启动子DNA甲基化水平，评价其作为诊断结直肠癌的敏感性和特异性。结果对照组、良性肠病组和肠癌组p16INK4A基因启动子DNA甲基化率分别为14.0%、24.4%和71.7%；MGM基因甲基化率分别为16.0%、14.6%和54.3%；ECAD基因甲基化率分别为12.0%、19.5%和65.2%。上述基因启动子甲基化率在肠癌组明显高于对照组和良性肠病组，差异均有统计学意义(P<0.05)；p16INK4A、MGMT和ECAD诊断肠癌的敏感性分别为0.72、0.54和0.65，特异性分别为0.76、0.75和0.80。结论 p16INK4A、MGMT和ECAD基因启动子甲基化发生率在肠癌患者粪便中显著增高，可作为肠癌诊断的分子标志物。

Clinical value of MGMT,p16INK4A and ECAD gene promoter methylation in the diagnosis of colorectal cancer

Objective To investigate the clinical value of MGMT, p16INK4A and ECAD gene promoter methylation in the diagnosis of colorectal cancer. Methods Fifty healthy people of more than 65 years old (control group), 41 patients of benign colorectal disease (benign colorectal disease group) and 46 patients with colorectal cancer (colorectal cancer group) in Department of Geriatrics from February 2014 to November 2015 were included in this study. The methylation levels of p16INK4A, MGMT, ECAD gene promoter in the stool of the three groups were assayed by methylation specific PCR. The diagnostic value of the p16INK4A, MGMT and ECAD methylation were calculated according to the Baye's equation. Results The methylation rates were 14.0%, 24.4%and 71.7%for p16INK4A gene in the three groups, 16.0%, 14.6% and 54.3% for MGMT gene, and 12.0%, 19.5% and 65.2% for ECAD gene respectively, with statistically significant difference between colorectal cancer group and benign colorectal disease group, control group (P<0.05). The diagnostic sensitivity was 0.72, 0.54 and 0.65, respectively, and the specificity was 0.76, 0.75 and 0.80 for p16INK4A, MGMT and ECAD, respectively. Conclusion The methylation rate of p16INK4A, MGMT and ECAD gene promoter in colorectal cancer patients' stool are significantly increased, which can be used as a molecular marker for colorectal cancer diagnosis.