结直肠癌患者粪便p16INK4a、MGMT、RASSF1A基因甲基化状态观察

摘要

目的 观察结直肠癌(CRC)患者粪便p16INK4a、MGMT、RASSF1A基因甲基化状态.方法 CRC患者50例(肿瘤组)、结直肠良性病变者50例(良性组)、健康体检者50例(正常组),采用甲基化特异度PCR的方法检测各组粪便p16INK4a、MGMT、RASSF1A基因甲基化检出率,并分析其与CRC临床病理参数的关系.根据肠镜病理诊断结果进行验证,比较粪便p16INK4a、MGMT、RASSF1A单独及联合检测诊断CRC的敏感度和特异度.结果 肿瘤组、良性组、正常组粪便p16INK4a基因甲基化检出率分别为74%、28%、14%,MGMT基因甲基化检出率分别为56%、24%、12%,RASSF1A基因甲基化检出率分别为72%、20%、10%,肿瘤组分别与正常组、良性组比较,P均<0.05.p16INK4a基因甲基化状态与CRC分化程度、TNM分期、淋巴结转移相关,MGMT基因甲基化状态与CRC淋巴结转移相关,RASSF1A基因甲基化状态与CRC分化程度、TNM分期、淋巴结转移相关,P均<0.05.三者联合检测诊断CRC的敏感度为95.8%,特异度为83.4%,ROC曲线下面积为0.816(95%CI 0.739%~0.894%).结论 CRC患者粪便p16INK4a、MGMT、RASSF1A基因甲基化检出率明显高于结直肠良性病变者及健康体检者,联合检测上述指标有助于CRC患者的早期诊断及其生物学行为的判断.%Objective To observe the gene promoter methylation of p16INK4a, MGMT, and RASSF1A in stool of patients with colorectal cancer (CRC).Methods Fifty healthy examined people (control group), 50 patients with benign colorectal disease (benign colorectal disease group) and 50 CRC patients (CRC group) were enrolled in the study.The p16INK4a, MGMT and RASSF1A promoter methylation detection rates in stool were detected by metilylation specific PCR (MSP).The correlation between p16INK4a, MGMT and RASSF1A promoter methylation levels and clinical parameters were analyzed by using statistic method.The sensitivity and specificity of p16INK4a, MGMT, and RASSF1A alone and in combination for the diagnosis of CRC were compared by using Bay''''s equation on the basis of pathological diagnosis.Results The detection rates for p16INK4a methylation were 74%, 28%, and 14% in the CRC group, benign colorectal disease group, and control group, 56%, 24%, and 12% for MGMT gene, and 72%, 20%, and 10% for RASSF1A gene, respectively.Statistically significant difference was found between the control group, benign colorectal disease group, and CRC group (all P<0.05).Additionally, correlation analysis showed that both p16INK4a and RASSF1A gene methylation was significantly associated with differentiated degree of CRC, TNM stage, and lymph node metastasis, while MGMT was correlated with lymph node metastasis (all P<0.05).The diagnostic sensitivity and specificity for combination of p16INK4a, MGMT, and RASSF1A was 95.8% and 83.4%, respectively.The ROC area under curve was 0.816 (95%CI: 0.739%-0.894%).Conclusions The methylation levels of p16INK4a, MGMT and RASSF1A in stool from CRC patients are significantly higher than those of patients with benign colorectal disease and healthy people.The combined detection of these three genes in stool is useful for early diagnosis of CRC and prediction of biological function of CRC.