Dihydrotestosterone regulation of cyclooxygenase-2 expression in bovine endometrial epithelium cells by androgen receptor mediated EGFR/PI3K/ Akt pathway

Uterine prostaglandins F2 alpha (PGF2 alpha) is essential for implantation, initiation of luteolysis and delivery. Previous studies have demonstrated that the expression of Cyclooxygenase-2 (COX-2), an enzyme limiting PGF2 alpha rate, is regulated by steroid hormones, and also dihydrotestosterone (DHT) may be involved in regulating COX-2 expression both positively and negatively. However, it remains unclear how whether DHT regulates COX-2 expression and consequent PGF2 alpha release in bovine endometrial epithelial cells (EECs). In this study, we eval-uated the localization of the two isoforms of DHT synthetase 5 alpha-reductase (5 alpha-red1 and 5 alpha-red2) and androgen receptor (AR) in bovine endometria by immunohistochemistry, and investigated 5 alpha-red1, 5 alpha-red2, AR, and DHT levels at the different stages of endometria (follicle, early-, mid-, and late-pregnancy phases). The results showed that 5 alpha-red1, 5 alpha-red2 and AR all were expressed in endometria, and their expressions and the level of DHT significantly increased in the late-pregnancy phase compared with the mid-pregnancy phase. Moreover, we cultured EECs from the mid-pregnancy phase and the in vitro study showed that DHT dose-dependently increased COX-2 expression and PGF2a release, but AR antagonist (flutamide) inhibited the stimulating effect via DHT. In addition, the DHT-induced COX-2 expression and PGF2 alpha release were subjected to the regulation of both EGFR/ PI3K/Akt/NFkB signaling as the inhibitors of EGFR (AG1478) and PI3K/Akt (LY294002) and NFkB (QNZ) attenuated the DHT mediated effect. Taken together, the results demonstrated that DHT-induced COX-2 expression and consequent PGF2 alpha release in bovine EECs were mediated through AR-derived EGFR trans-activation and PI3K/Akt cascade leading to NFkB activation.

Automated summary

In this study, we investigated the regulation of DHT on COX-2 expression and PGF2 alpha release in bovine EECs, finding that DHT dose-dependently increased COX-2 expression and PGF2 alpha release. This effect was mediated through AR-derived EGFR trans-activation and the PI3K/Akt cascade leading to NFkB activation, as confirmed by EGFR, PI3K/Akt, and NFkB inhibitors attenuating the DHT-mediated effect.