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

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)-negative and 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. Copyright © 2013 by TUMOR.