While estrogens are important in prostate growth and play a role in benign prostatic hyperplasia (BPH), no current therapies directly target estrogen action. Estrogens act primarily via estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ). Using a mouse model, we evaluated the relative contribution of these receptors to bladder complications of BPH. We also evaluated prevention of these bladder complications by selective estrogen receptor modulators (SERMs), raloxifene and tamoxifen (ERα selective antagonists) and (R,R)-5,11-Diethyl-5,6,11,12-tetrahydro-2,8-chrysenediol (R,R-THC, ERβ selective antagonist).
Materials and Methods
Adult male C57bl/6 mice received implants of 25 mg testosterone (T) and 2.5 mg 17β-estradiol (E2) slow release pellets and untreated controls underwent sham surgery. We used ERα and ERβ knockout (KO) mice compared to their respective wild type (WT) littermates to probe contributions of ER subtypes. WT mice treated with T+E2 were compared to mice treated with T+E2 and 25 mg SERM to evaluate prevention of BPH complications with SERMs.
While ERαWT and ERβWT littermates treated with T+E2 developed large bladders with urinary retention, ERαKO mice treated with T+E2 did not. ERβKO mice treated with T+E2 developed large bladders with urinary retention and increased bladder mass. Co-treatment with the ERα antagonist raloxifene resulted in decreased bladder mass compared to WT mice treated with T+E2, while bladders from mice treated with the ERβ antagonist R,R-THC were similar to T+E2-treated mice.
ERα, but not ERβ, is a key mediator of bladder complications of BPH, and is a potential target for future therapies.