BRIP1 overexpression is correlated with clinical features and survival outcome of luminal breast cancer subtypes.

In Oman, breast cancer is most common, representing approximately more than 25% of all cancers in women. Relatively younger populations of patients (25-40 years) present surprisingly with an aggressive phenotype and advanced tumor stages. In this study, we investigated differential gene expressions in Luminal A, Luminal B, triple-negative and Her2+ breast cancer subtypes and compared data to benign tumor samples. We identified a potential candidate gene BRIP1, showing differential expression in the four breast cancer subtypes examined, suggesting that BRIP1 has the profile of a useful diagnostic marker, suitable for targeted therapeutic intervention. RT-qPCR and Western blotting analysis showed higher BRIP1 expression in luminal samples as compared to triple-negative subtype patient's samples. We further screened BRIP1 for eventual mutations/SNPs/deletions by sequencing the entire coding region. Four previously identified polymorphisms were detected, one within the 5'-UTR region (c. 141-64G > A) and three in the BRCA-binding domain (c. 2755T > C, c. 2647G > A and c. 3411T > C). Kaplan-Meier analysis revealed that patients with overexpression of BRIP1 displayed a poor survival rate (P < 0.05). BRIP1 has a dual function of an oncogene and a tumor suppressor gene in addition to its role as a potential biomarker to predict survival and prognosis. Data obtained in this study suggest that BRIP1 can plausibly have an oncogenic role in sporadic cancers.