Critical role for BRCA1 expression as a marker of chemosensitivity response and prognosis.

Chemotherapy is still the leader option for cancer treatment. Nevertheless some patients develop chemotherapy resistance. One major research goal is to identify the critical genes involved in chemotherapy response to predict the best therapy option for patients. Germline mutations in the BReast Cancer susceptibility gene (BRCA1) are associated to increased risk of developing breast, ovarian and other types of cancers. However, due to harmful BRCA1 gene mutations are relatively rare in the general population, nowadays most researchers focused on BRCA1 expression downregulation and/or epigenetic inactivation in sporadic tumors as a prognosis tool for chemotherapy response in patients. Chemotherapy response can be dramatically different depending on BRCA1 expression status, tumor type and drug. Hence, the chemotherapy response could be dissimilar in breast, ovarian, uterine, prostate, esophageal, gastric and lung cancers. Additionally, differential BRCA1 expression in sporadic tumors shows different response to DNA-damaging agents, mitotic inhibitors or PARP inhibitors. In this review we will examine the response to different chemotherapy agents in several cancer types depending on BRCA1 expression status.