乳腺癌患者外周血清中APC基因启动子甲基化异常的检测及其意义

背景与目的:检测肿瘤患者外周血中肿瘤相关标志物是当前肿瘤研究的热点之一,恶性肿瘤患者外周血中存在游离的肿瘤相关DNA已引起肿瘤学界的极大关注,人们曾在多种肿瘤患者血清中发现与原发肿瘤相同的DNA变异.本研究以APC(adenomatous polyposis coli)基因启动子甲基化作为肿瘤标志物,探讨乳腺癌患者外周血清中游离的肿瘤相关DNA与肿瘤组织及临床病理参数的相关性.方法:采用甲基化特异性PCR(methylation specific-PCR,MSP)方法,分别检测84例乳腺癌组织、癌旁正常腺体组织及外周血清中游离DNA APC基因启动子甲基化状况.结果:84例乳腺癌组织APC基因启动子甲基化频率为45.2%(38/84),相应外周血清中同样DNA变异阳性检出率为31.0%(26/84).外周血清中DNA甲基化变异与肿瘤组织的甲基化状况显著相关(r=0.977,P=0.002).检测外周血清中APC基因甲基化的敏感性为68.4%,特异性为97.8%.肿瘤组织及外周血清中游离DNA甲基化异常与临床分期、病理类型、肿块大小及受体状况无相关性(P＞0.05).肿瘤组织未检测到甲基化患者的血清中及健康人血清中均未检测到该基因甲基化变异.结论:乳腺癌患者外周血清中肿瘤相关DNA甲基化与肿瘤组织中相同基因的变异显著相关.

Detection and significance of APC gene promoter hypermethylation in serum of breast cancer patients

BACKGROUND & OBJECTIVE:Detection of circulating tumor markers is one of current hot spots in tumor research.Free tumor DNA may exist in the peripheral blood of malignant tumor patients.Identical DNA mutations existing in both peripheral serum and primary tumor are found in many kinds of malignant tumors.This study used adenomatous polyposis coli(APC) gene promoter hypermethylation as a tumor marker to investigate the correlations of free tumor DNA to primary tumor and clinicopathologic features of breast cancer.METHODS:The methylation status of APC gene in tumor tissue,paracancer normal tissue,and paired peripheral serum from 84 patients with breast cancer and 10 patients with benign breast diseases were detected by methylation-specific polymerase chain reaction(MSP).RESULTS:The detection rate of APC gene promoter hypermethylation was 45.2% in tumor tissues and 31.0% in paired peripheral sera.APC gene hypermethylation in peripheral serum was significantly correlated to that in tumor tissue(r=0.977,P=0.002).The sensitivity of detecting APC gene hypermethylation in peripheral serum was 68.4%;the specificity was 97.8%.The aberrant methylation of APC gene in tumor tissue and peripheral serum had no correlation to patients' age,tumor stage,tumor size,histological type,and receptor status(P>0.05).No aberrant methylation of APC gene was found in the serum samples from healthy control and the patients without gene methylation in tumor tissue.CONCLUSION:The aberrant tumor gene methylation in peripheral serum of breast cancer patients is significantly correlated to that in primary tumor.