| Abstract [eng] |
Breast cancer is the most prevalent malignancy of women in Lithuania and word-wide. The course of disease differ markedly among patients, therefore molecular characterisation of tumour is very important. However, current prognostic markers are mainly based on clinical parameters and do not enable a reliable selection of the patients with high risk of disease progression. Molecular characterisation of tumour through detection of changes in cancer-related genes can help to estimate the risk of cancer progression, detect the molecular targets for modern treatment strategies. In order to evaluate the suitability of epigenetic biomarkers for molecular characterisation of breast cancer we analysed promoter hypermethylation in a wide panel of regulatory genes involved in cell cycle control, signalling, apoptosis and DNA repair. 76 primary breast carcinomas of early stage (pT1-2) were selected for the study. Aberrant methylation in promoter regions of seven tumour suppressor genes (p16, p14, RARβ, RASSF1A, DAPK, GSTP1 and MGMT) was analysed by means of methylation-specific PCR. The “Real Time” PCR method was adapted for detection of epigenetic changes in circulating tumour DNA from plasma of cancer patients. Most of the early-stage breast tumours (63/76) exhibited hypermethylation in at least one gene involved in analysis. The overall sensitivity of the epigenetic biomarkers was 83%. Gene RASSF1A was the most frequently (56 of 76 cases) hypermethylated gene in breast tumours. Statistical analysis revealed significant associations between expression of hormonal receptors (ER and PR) and hypermethylation of gene RASSF1A, expression of HER-2 and hypermethylation of gene GSTP1, hypermethylation of gene RARβ and poor differentiation (G2-3) of the tumours. Our study shows a significant involvement of epigenetic changes in the early stage breast carcinomas. After thorough analysis in the bigger groups of patients a set of analysed biomarkers can be used as the molecular biomarkers of breast cancer. |
