Abstract
Tissue-based biomarkers that identify women with increased breast cancer risk are needed for cancer prevention. Enhancer of zeste 2 (EZH2) and fatty acid synthase (FASN) are associated with breast cancer aggressiveness, but their expression in normal breast tissues and association with breast cancer risk factors are unclear. Further, there is a need to characterize healthy breast tissue cohorts for unbiased biomarker evaluation. In this study, we employed the Susan G. Komen healthy volunteer tissue bank to evaluate EZH2 and FASN expression and their relationship to breast cancer risk factors. Normal breast core biopsies from 40 healthy donors with low or high Gail scores (<11 or >20, respectively) and normal or obese body mass index (BMI, <25 kg/m 2 or >30 kg/m 2 , respectively) were stained for H&E, EZH2, and FASN and scored independently and blindly using the Allred method. We analyzed the associations between EZH2 and FASN with Gail score, BMI, menopausal status, hormone replacement therapy (HRT), and family history of breast cancer. None of the donors had BRCA1/2 mutations or developed breast cancer after 5 to 9 years. We found that premenopausal women had significantly higher expression of FASN and that EZH2 was higher with increasing Gail risk scores, compared with postmenopausal women. In postmenopausal women, increased EZH2 expression was associated with >5 years of HRT compared with <1 year or no HRT. No associations were found with BMI. This study provides validation of a healthy breast tissue cohort and initial characterization of EZH2 and FASN and their associations with breast cancer risk factors.