Analysis of EMSY, a novel BRCA2-link protein, in primary breast tumors; a study using tissue microarray

Background: The EMSY gene has been anticipated as a driver of the third core of the 11q13-q14 amplicon that encodes a BRCA2-binding partner protein. Its over-expression can inhibitBRCA2 functions leading to BRCA2 inactivation in non-hereditary breast and ovariancancers. The amplification of EMSY has been associated with decreased survival as well asan increased risk of relapse in breast cancer patients.Material & Methods: The purpose of the current study was to examine the expression andlocalization of EMSY protein and to assess its prognostic value and patients outcome, in awell-characterized series of 116 unselected breast carcinomas using tissue microarray andimmunohistochemistry. The series included patients 79 years of age or less (mean = 52 years)with a long-term follow-up of 2-180 months (mean=47 months) whom diagnosed between1996 and 2010.Results: The expression of EMSY protein was detected in 76% of primary breast tumorslocalized to the nuclear (18%), cytoplasm (35%) or both cytoplasm and nuclear sites (23%).Univariate analysis revealed a significant association between expression of EMSY withlymph node metastases (p-value=0.035) and larger tumor size (p-value= 0.045), as well as arelative association with increased risk of recurrence (p-value=0.088), while no associationwith patients’ survival (log rank=0.482), tumor type or grade was observed.Conclusion: Amplification of EMSY inhibits activation of BRCA2 leading to impairment ofDNA damage repair. Therefore, expression of EMSY protein would be related to anincreased risk of lymph node metastasis and larger tumor size.