多基因联合提高结直肠癌甲基化检测阳性率的研究

Multi-gene methylation detection increases positive methylation rate in colorectal cancer

目的探讨联合检测Vimentin、sFRP1和HPP1基因甲基化对提高结直肠癌甲基化阳性率的意义。方法收集90例结直肠癌（结直肠癌组）和60例腺瘤性息肉（腺瘤组）患者及20例结直肠正常组织（正常对照组）标本，提取组织标本的DNA，采用甲基化特异性PCR（MSP）检测Vimentin、sFRP1和HPP1基因甲基化状态。分析其与结直肠癌的关系及甲基化阳性率。结果结直肠癌组Vimentin、sFRP1和HPP1基因甲基化率分别为66．7％（60／90）、68．9％（62／90）和72．2％（65／90）；腺瘤组则分别为53.3％（32／60）、55．0％（33／60）和50．0％（30／60）；正常对照组分别为0、0和5．0％（1／20）。结直肠癌组3个基因甲基化阳性率均高于腺瘤组和正常对照组（P〈O．05）。3个基因甲基化联合检测诊断结直肠癌和腺瘤的阳性率分别为93．3％（84／90）和76．7％（46／60），高于单个基因检测的甲基化阳性率（P〈0．05）。3个基因甲基化状态与本组结直肠癌患者的性别、年龄、肿瘤部位、淋巴结转移、远处转移及TNM分期无关（P〉0．05）。结论Vimentin、sFRP1和HPP1基因启动子甲基化水平在结直肠癌组织中升高．其联合检测明显提高了结直肠癌甲基化检测阳性率．有可能成为结直肠癌早期诊断的甲基化检测方案。

Objective To study whether combined detection of the methylation status of vimentin, sFRP1, and HPP1 gene can increase the positive methylation rate in colorectal cancer. Methods Tissue samples were collected from 90 patients with colorectal cancer, 60 patients with adenomatous polyp, and 20 heathy controls. DNA was extracted and the methylation status of vimentin, sFRP1, and HPP1 gene was detected by Methylation-specific PCR （MSP）. The relationship between clinicopathologic features of colorectal cancer and gene methylation was analyzed. Results The methylation rates of vimentin, sFRP1, and HPP1 were 66.7%, 68.9%, and 72.2% in colorectal cancer, 53.3%, 55.0%, and 50.0% in colorectal adenomas, and O, 0, and 5.0% in healthy controls, respectively. The methylation of each of the three genes in eolorectal cancer tissues was higher than colorectal adenomas and healthy controls （P〈O.05）. The diagnostic sensitivity by combining three methylation markers was 93.3% in colorectal cancer, 76.7% in colorectal adenomas, which was higher than the sensitivity using single gene testing （P〈0.05）. No significant associations existed between the methylation status of the three genes and clinical characteristics including sex, age, tumor location, lymph node metastases, distant metastasis, and TNM stage （P〉0.05）. Conclusions DNA methylation levels of vimentin, sFRP1 and HPP1 are significantly higher in colorectal cancer tissue. Combined detection significantly improves the positive rate of methylation, and may be used as early diagnosis method for colorectal cancer.