The Role of BRCA1/2-Mutated Tumor Microenvironment in Breast Cancer

SIMPLE SUMMARY: The link between BRCA1/2 mutations and high susceptibility to breast cancer development has been well-established for years. However, the potential impact of BRCA1/2 mutations on the individual cell populations within the unique tumor microenvironment and their relation to breast cancer has been understudied. This review aims to provide significant insights into up-to-date knowledge about the role of BRCA1/2-mutated tumor microenvironment and possible mechanisms by which it interacts with and promotes breast cancer development and progression. Uncovering and exposing these mechanisms of the aberrant microenvironment might provide more effective strategies for treatment of germline mutation-carrying breast cancer patients. ABSTRACT: Taking into account the factors of high incidence rate, prevalence and mortality, breast cancer represents a crucial social and economic burden. Most cases of breast cancer develop as a consequence of somatic mutations accumulating in mammary epithelial cells throughout lifetime and approximately 5–10% can be ascribed to monogenic predispositions. Even though the role of genetic predispositions in breast cancer is well described in the context of genetics, very little is known about the role of the microenvironment carrying the same aberrant cells impaired by the germline mutation in the breast cancer development and progression. Based on the clinical observations, carcinomas carrying mutations in hereditary tumor-suppressor genes involved in maintaining genome integrity such as BRCA1/2 have worse prognosis and aggressive behavior. One of the mechanisms clarifying the aggressive nature of BRCA-associated tumors implies alterations within the surrounding adipose tissue itself. The objective of this review is to look at the role of BRCA1/2 mutations in the context of breast tumor microenvironment and plausible mechanisms by which it contributes to the aggressive behavior of the tumor cells.