Current pharmacotherapies for symptomatic benign prostatic hyperplasia (BPH), an androgen receptor (AR) driven, inflammatory disorder affecting elderly men, include 5α-reductase (5AR) inhibitors (i. e. dutasteride and finasteride) to block the conversion of testosterone to the more potent AR ligand dihydrotestosterone (DHT). Since DHT is the precursor for estrogen receptor β (ERβ) ligands, 5AR inhibitors could potentially limit ERβ activation, which maintains prostate tissue homeostasis. We have uncovered signaling pathways in BPH-derived prostate epithelial cells (BPH-1) that are impacted by 5AR inhibition. The induction of apoptosis and repression of the cell-adhesion protein E-cadherin by the 5AR inhibitor, dutasteride, requires both ERβ and TGFβ. Dutasteride also induces cyclooxygenase type 2 (COX-2), which functions in a negative-feedback loop in TGFβ and ERβ signaling pathways as evidenced by the potentiation of apoptosis induced by dutasteride or finasteride upon pharmacological inhibition or shRNA-mediated ablation of COX-2. Concurrently, COX-2 positively impacts ERβ action through its effect on the expression of a number of steroidogenic enzymes in the ERβ-ligand metabolic pathway. Therefore, effective combination pharmacotherapies, which have included non-steroidal anti-inflammatory drugs, must take into account biochemical pathways affected by 5AR inhibition and opposing effects of COX-2 on the tissue protective action of ERβ.
The Journal of biological chemistry. 2016 May 13 [Epub ahead of print]
Teresa T Liu, Melanie J Grubisha, Krystle A Frahm, Stacy G Wendell, Jiayan Liu, William A Ricke, Richard J Auchus, Donald B DeFranco
University of Pittsburgh, United States;, University of Pittsburgh, United States;, University of Pittsburgh, United States;, University of Pittsburgh, United States;, University of Michigan, United States;, University of Wisconsin-Madison, United States., University of Michigan, United States;, University of Pittsburgh, United States; .