Clinical significance of PDEF factor expression and its relation to androgen receptor in ER- breast cancer.

ABSTRACT

AIMS: The mechanism of androgen receptor (AR) promoting tumour growth in oestrogen receptor-negative (ER- ) breast cancer (BC) is undetermined. Prostate-derived ETS factor (PDEF) is highly restricted to the hormone-regulated tissues of epithelial cells, such as those in the prostate, breast and other tissues. It has been demonstrated that PDEF expression is associated with AR in prostate cancer. In this research, we aimed to investigate the relationship between PDEF and AR in ER- BC. METHODS AND RESULTS: We immunohistochemically evaluated the correlation between PDEF and AR expression in 246 cases of ER- invasive BC, and investigated their relationship in ER- BC cell lines. The expression of PDEF was associated with the positive expression of AR (P < 0.001) and a worse survival rate (P = 0.006). PDEF+ tumours were significantly more often AR+ (P < 0.001). AR and PDEF were more often co-expressed and the series of AR+ PDEF+ (126 of 246, 51.2%) had a poor survival rate (P = 0.046). In Cox models, PDEF expression (P = 0.028) was an independent predictor for overall survival (OS). At the cellular protein and mRNA levels, our experiments also showed a statistically significant positive correlation between PDEF and AR, and that PDEF may be regulated by AR. CONCLUSIONS: PDEF is associated with markers of bad prognosis, supporting its role as a growth promoter in ER- BC. Our findings also provide evidence that PDEF is strongly correlated with AR expression in ER- breast cancer; it may be a downstream target gene of AR and a potential prognostic factor in ER- BC.