RESUMO
Background and purpose:Aberrant DNA methylation that leads to the inactivation of tumor suppressor genes plays important roles in development and progression of breast cancer. Clinically, related gene methylation is considered to be a promising biomarker for tumor diagnosis and prognosis. This study aimed to investigate the methylation status ofSox17 gene in breast cancer tissue and its corresponding plasma circulating DNA, as well as to investigate its value in breast cancer early diagnosis and prognosis.Methods:TheSox17 gene promoter methylation status was detected by MSP in 86 cases of breast cancer, 36 normal breast tissues and its paired plasma DNA, the results were analyzed with corresponding clinical and pathological features.Results:The frequency ofSox17 gene methylation rate among 86 breast cancer tissues was 77.9%(67/86), and was 61.6%(53/86)in plasma circulating DNA, however, noSox17 gene methylation was found in normal breast tissues.Sox17 gene promoter methylation in plasma circulating DNA was signiifcantly associated with the methylation status in tumor tissues (r=0.502,P=0.000). In breast cancer tissue specimens,Sox17 methylation status was significantly correlated with tumor stage (χ2=6.18,P=0.041) and lymph node metastasis (χ2=13.54,P=0.001);Sox17 gene methylation rate was signiifcantly correlated with tumor stage (χ2=27.06,P=0.000), tumor size (χ2=9.65,P=0.007) and lymph node metastasis (χ2=20.80,P=0.000) in plasma samples, and there was no signiifcant difference ofSox17 gene methylation between patient age, histological grade and ER, PR, HER-2/neu status.Conclusion:Sox17 gene promoter methylation plays an important role in the carcinogenesis and development of breast cancer, and may be associated with the prognosis of breast cancer. Furthermore, methylatedSox17 gene may be a useful tumor biomarker in plasma circulating DNA for breast cancer detection and disease monitoring.