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目的研究人粪便中分泌型卷曲相关蛋白2(SFRP2)、增生性息肉蛋白(HPP1)和 O~6-甲基鸟嘌呤 DNA 甲基转移酶(MGMT)基因甲基化状态及其用于结直肠癌(CRC)筛查的可行性。方法从52例 CRC 患者、35例结直肠良性疾病患者和24名正常对照者粪便标本中提取 DNA,采用甲基化特异性 PCR(MSP)技术分析粪便 DNA 中 SFRP2、HPP1和 MGMT 基因甲基化状态。结果 CRC患者粪便 SFRV2、HPP1和MGMT 基因甲基化阳性率分别为94.2%、71.2%和48.1%;96.2%的 CRC和81.8%的癌前病变患者中至少存在1个基因的过甲基化。1例正常粪便标本 SFRP2甲基化阳性。联合3个基因诊断 CRC 和癌前病变的敏感度、特异度、阳性预测值和阴性预测值分别为93.7%、77.1%、84.3%和90.2%。结论联合分析 SFRP2、HPP1和 MGMT 基因甲基化是检测 CRC 及癌前病变的高敏感性方法。检测粪便基因甲基化有望成为 CRC 无创诊断或高风险人群筛查的一个新途径。
Objective To study the methylation status of secreted curly-associated protein 2 (SFRP2), proliferative polyploid protein (HPP1) and O-6-methylguanine DNA methyltransferase (MGMT) gene in human feces and its application in colorectal Feasibility of cancer screening. Methods DNA was extracted from stool specimens from 52 CRC patients, 35 colorectal benign disease patients and 24 normal controls. Methylation-specific PCR (MSP) was used to analyze the methylation of SFRP2, HPP1 and MGMT genes in stool DNA status. Results The methylation-positive rates of SFRV2, HPP1 and MGMT in stool samples of CRC patients were 94.2%, 71.2% and 48.1% respectively. There was at least one gene hypermethylation in 96.2% of CRC and 81.8% of precancerous lesions. One case of normal stool specimens SFRP2 methylation was positive. The sensitivity, specificity, positive predictive value and negative predictive value of combined 3 gene diagnosis of CRC and precancerous lesions were 93.7%, 77.1%, 84.3% and 90.2% respectively. Conclusions Combined analysis of methylation of SFRP2, HPP1 and MGMT genes is a highly sensitive method to detect CRC and precancerous lesions. Detection of stool gene methylation is expected to be a new way for noninvasive diagnosis of CRC or screening for high-risk populations.