EMSY copy number variation in male breast cancers characterized for BRCA1 and BRCA2 mutations

Male breast cancer (MBC) is a rare disease that shares some similarities with female breast cancer (FBC). Like FBC, genetic susceptibility to MBC can be referred to mutations in BRCA1 and, particularly, BRCA2 genes. However, only about 10 % of MBCs are caused by BRCA1/2 germ-line mutations, while the largest part are sporadic cancers and may derive from somatic alterations. EMSY, a BRCA2 inactivating gene, emerged as a candidate gene involved in the pathogenesis of sporadic FBC, and its amplification was suggested to be the somatic counterpart of BRCA2 mutations. Considering the relevant role of BRCA2 in MBC, we aimed at investigating the role of EMSY gene copy number variations in male breast tumors.

EMSY copy number variations were analyzed by quantitative real-time PCR with TaqMan probes in a selected series of 75 MBCs, characterized for BRCA1/2 mutations.

We reported EMSY amplification in 34.7 % of MBCs. A significant association emerged between EMSY amplification and BRCA1/2 mutations (p = 0.03). We identified two amplification subgroups characterized by low and high amplification levels, with BRCA2-related tumors mostly showing low EMSY amplification.

Our results show a high frequency of EMSY amplification in MBC, thus pointing to a role of EMSY in the pathogenesis of this disease. EMSY amplification may be a new feature that might uncover underlying molecular pathways of MBCs and may allow for the identification of MBC subgroups with potential clinical implication for targeted therapeutic approaches.