ABSTRACT
DNA methylation of promoter regions is a common molecular mechanism for inactivation of tumor suppressor genes that participates in carcinogenesis. Determining the methylation status of genes in cancer and their association with clinical features play an essential role in early diagnosis, prognosis and determine appropriate treatment for patients. The purpose of the present study was to evaluate the methylation of tumor suppressor genes in patients with invasive ductal carcinoma (IDC). Furthermore, we evaluated the association between clinical parameters and DNA methylation as a biomarker in diagnostic IDC patients. The methylation-specific multiplex ligation dependent probe amplification (MS-MLPA) assay was used to analyze the methylation profile of 24 genes in formalin-fixed paraffin embedded (FFPE) tissue samples from 75 patients with IDC. Each of the patients showed a distinctive methylation profile. We observed higher methylation in the RASSF1 (48 %), CDH13 (44 %) and GSTP1 (36 %) genes. Some of the methylated genes were associated with clinical features. Methylation of GSTP1 (P=0.028) and RASSF1 (P=0.012) were related with lymph node metastasis. Methylation of GSTP1 (P=0.005) was associated with high histological grade. Moreover, concurrent methylation of GSTP1 and CDH13 was observed in IDC patients (p<0.001). Hierarchical cluster analysis based on the methylation profile revealed two main clusters of patients, the highly methylated cluster being significantly associated with high histological grade and lymph node metastasis. The results of this study indicate that the methylation status of RASSF1 and CDH13 and GSTP1 can be a prognostic marker to better management of IDC patients.
ABSTRACT
BACKGROUND: Promoter methylation of tumor suppressor genes is an important epigenetic alteration that occurs in the primary stages of human tumors, including breast cancer. Identification of methylated genes and their relationship to clinical features can contribute to the prognosis and early detection of tumors. In this study, we explored the methylation status of APC and BRCA1 genes and their relationship to clinical factors in breast cancer patients. METHODS: BRCA1 and APC promoter methylation was examined by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) assay in formalin-fixed paraffin embedded (FFPE) breast tissue from 75 patients. RESULTS: APC promoter methylation was detected in 30.67% breast cancer tissues and BRCA1 was methylated in 9.33% of breast tumors. Methylation of APC was associated with low histological grade (p = 0.006) and methylation of BRCA1 was related with lymph node metastasis (p = 0.017). CONCLUSIONS: These findings suggest that the methylation status of APC and BRCA1 can be a predictive marker for early detection and better management of breast cancer patients.
