Contribution of epigenetic alteration of BRCA1 and BRCA2 genes in breast carcinomas in Tunisian patients.

OBJECTIVE

The aim of this study was to evaluate the contribution of the BRCA1 and BRCA2 promoter methylation in the pathogenesis of sporadic breast cancer in Tunisian patients.

METHODS

Breast carcinoma tissues (n=117) and available paired normal breast tissues (n=65) from Tunisian women who had no family history were investigated for the methylation status of BRCA1 and BRCA2 promoters using methylation-specific PCR. Breast specimens from women without carcinoma (16 fibroadenomas and 5 mastopathies) were used as control.

RESULTS

Hypermethylation of BRCA1 and BRCA2 promoters was detected respectively in 60.7% and 69.2% of the carcinoma tissues, and in only 7.7% and 4.6% of the paired normal breast tissues. None of the fibroadenomas and mastopathies showed hypermethylation. Correlations were found between BRCA1 and BRCA2 hypermethylation and decrease in their mRNA expression (p=0.02 and p=0.009, respectively). Moreover, BRCA1 methylation correlates with patients age (p=0.01) and triple negative (ER-, PR-, HER2-) tumors (p=0.01). Patients with methylated BRCA1 and/or BRCA2 had a significant prolonged survivals compared to those with unmethylated tumors (p=0.002).

CONCLUSION

Our results suggest an important role of BRCA1 and BRCA2 promoter methylation in breast cancer development in the Tunisian population.