Résumé
Ras-associated domain family 1 [RASSF1A] and hypermethylated in cancer [HIC1] genes are methylated more frequently in breast cancer. Genetic factors that alter the DNA methylation levels in normal and tumor tissues could therefore influence the susceptibility to this tumor phenotype. We determined the frequency of aberrant methylation of HIC1 and RASSF1A gene promoters and their association with methylene tetrahydrofolate dehydrogenase [MTHFD1] G1958A polymorphism and major clinical and pathological features of breast cancer in Iranian women. DNA was extracted from 81 primary breast tumors and 100 control blood samples. Gene promoter methylation was analyzed by methylationspecific polymerase chain reaction. Eighty four percent of the breast cancer samples showed total methylation in at least one of two tested loci. We detected HIC1 hypermethylation in 79% of invasive and metastasis tumors and RASSF1A gene hypermethylation in 51% of them. We found no association between HIC1 and RASSF1A gene hypermethylation and MTHFD1 G1958A polymorphism, but a significant correlation between methylation of HIC1 and RASSF1A promoters was indicated [r = 0.24, P = 0.02]. There was a combination between hypermethylation of HIC1 locus and nodal involvement in the studied population [p=0.03]. We found a significant association between total methylation and nodal involvement [P=0.01] as well as tumor size more than 2 cm in all cases [P=0.02]. Methylation of HIC1 and RASSF1A promoters can be used as epigenetic markers to detect the malignant progression of breast carcinoma in Iranian women patients