Role of ERβ in Triple-Negative Breast Cancer Associated with p53 and Androgen Receptor

In triple-negative breast cancer (TNBC), the clinicopathological significance of the expression of a second estrogen receptor, ERβ, remains unclear. Further, although the clinicopathological significance of mutant p53 and androgen receptor (AR) has been investigated in TNBC, they have not been established as therapeutic targets. Experimental studies reported the importance of cross-talk between ERβ and p53 or AR in TNBC. In this study, we immunohistochemically examined ERβ expression in surgical specimens of TNBC obtained from postmenopausal patients who underwent surgery without neoadjuvant therapy and investigated the relationship between ERβ expression and various clinicopathological factors, including clinical outcome, while also considering p53 and AR. No significant difference in clinical outcome was noted according to the ERβ status alone (p = 0.2908). However, the ERβ status did affect the relationship between the clinical outcome and p53 or AR status; p53-positive or AR-positive group exhibited significantly more favorable clinical outcomes than p53-negative or AR-negative group, respectively, in the ERβ-positive group (p53, p = 0.0265; AR, p = 0.0285), but not in the ERβ-negative group (p53, p = 0.7228; AR, p = 0.7734). This may be the result of a functional interaction between ERβ and p53 or AR. The role of ERβ in TNBC will be elucidated in further complex studies considering multiple molecules.