乳腺癌患者外周血DNA中PTPRO基因甲基化异常的检测及其临床意义

Detection of aberrant PTPRO gene methylation in peripheral blood and its clinical significance in breast cancer patients

目的 :研究膜结合受体型蛋白酪氨酸磷酸酶O(protein tyrosine phosphatase receptor-type O,PTPRO)基因启动子在乳腺癌组织及其相应的外周血DNA中的甲基化状况,并探讨乳腺癌患者外周血中游离的肿瘤相关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 speciic-PCR,MSP)法检测乳腺癌组织、癌旁正常腺体组织及外周血中游离DNA中PTPRO基因启动子甲基化状况,并结合其临床病理特性进行分析。结果 :98例乳腺癌组织中PTPRO基因启动子的甲基化率为55.1%(54/98),与其相应外周血DNA中PTPRO基因启动子的甲基化率为33.7%(33/98),而对照组正常乳腺组织中无1例有PTPRO基因启动子的甲基化。外周血中PTPRO基因启动子的甲基化与肿瘤组织的该基因的甲基化状况显著相关(r=17.083,P=0.000)。甲基化率与患者肿瘤分期(r=9.649,P=0.001)、组织学分级(r=2.476,P=0.035)、淋巴结转移(r=3.400,P=0.003)、ErbB2阳性呈正相关(r=4.912,P=0.000);雌激素受体(estrogen receptor,ER)阴性及孕激素受体(progestogen receptor,PR)阴性的肿瘤组织中PTPRO基因启动子甲基化率增高,但差异无统计学意义。肿瘤组织中未检测到甲基化的患者及健康人血浆中均未检测到该基因甲基化变异。结论 :PTPRO基因启动子甲基化在乳腺癌的发生和发展中起着重要作用,可能与乳腺癌的预后相关,外周血中PTPRO基因甲基化的检测可作为一种无创性的乳腺癌临床诊断分子生物学指标。

Objective： To study the methylation status of PTPRO （protein tyrosine phosphatase receptor-type O） gene as a potential biomarker in the detection of breast cancer, and to analyze its association with clincopathologic features. Methods＇- The PTPRO gene promoter methylation status in primary human breast tumors, normal breast tissues and peripheral blood were detected by MSP （methylation specific-PCR）, and the results were analyzed with corresponding clinico pathological data. Results： The frequency of PTPRO gene mehtylation among 98 breast cancer tissues were 55.1% （54/98）, and 33.7% （33/98） in peripheral blood, however no PTPRO gene mehtylation was found in normal breast tissues. PTPRO gene methylation in peripheral blood was significantly correlated to that in tumor tissue （r = 17.083, P = 0.000）. PTPRO methylation was associated with tumor stage （r = 9.649, P = 0.001）, histological grade （r = 2.476, P = 0.035）, lymph node metastasis （r = 3.400, P = 0.003） and ErbB2-positive （r = 4.912, P = 0.000）. Patients with ER （estrogen receptor）-negativeand PR （progestogen receptor）-negative had more PTPRO methylation, but the difference was not statistically significant. No aberrant methylation of PTPRO gene was found in the plasma samples from healthy control and the patients without gene methylation in tumor tissues. Conclusion： PTPRO gene promoter mehtylation may play an important role in the carcinogenesis and development of breast cancer. It might be used to predict the prognosis of breast cancer patients. Furthermore, this is the first report of methylated PTPRO as a noninvasive tumor biomarker in peripheral blood of breast tumor patients for detection and disease monitoring.