Molecular Genetics, Diagnosis and Treatment of Breast Cancer: Review Article

Breast cancer is the most common cancer among women, and one out of 8 or 10 women is diagnosed with breast cancer. This type of cancer is an extremely heterogenous disease, which is classified into multiple categories including LCIS (Lobular carcinoma in situ), DCIS (Ductal carcinoma in situ), and invasive carcinoma. BRCA1 and BRCA2 are two major high-risk genes associated with hereditary breast cancer. Mutations in CHEK2 gene also contribute to a substantial fraction of familial breast cancer. Susceptibility alleles in other genes are also rare causes of breast cancer. More than 1000 mutations have been identified in BRCA1 and BRCA2, and molecular assays for detecting mutations in these genes are now well established. Mutations in BRCA1 and BRCA2 cause genomic instability, which leads to alterations in additional key genes including tumor suppressor genes and/or oncogenes. There is a promise of tailoring treatment programs for individual women in near future. The emergence of miRNAs as regulators of gene expression identifies them as a novel candidate for diagnostic and prognostic indicators and therapeutic targets. The ability of miRNAs to simultaneously regulates many target genes and makes them attractive candidates for regulating stem cell self-renewal and cell fate decisions. The involvement of miRNAs in the initiation and progression of human malignancy holds much potential for new developments in current diagnostic and therapeutic strategies in the management of patients with breast cancer. The identification of novel miRNAs, the elucidation of their mRNA targets, and an understanding of their functional effects will improve our knowledge of the roles of these novel biomarkers in carcinogenesis, including breast cancer, and open avenues for potential therapeutic intervention.