Cross-talk between androgen receptor and pregnane and xenobiotic receptor reveals existence of a novel modulatory action of anti-androgenic drugs

Abstract

The androgen receptor (AR) is a member of nuclear receptor superfamily (NRs) and plays a critical role in prostate cancer development and progression. Therefore, anti-androgens that repress AR activity remain a critical mainstay for prostate cancer therapy. However, molecular mechanisms by which anti-androgens exert their therapeutic effects are not clearly elucidated and hence are a major area of scientific pursuit. Here, we demonstrate that another member of NRs, pregnane and xenobiotic receptor (PXR), not only acts as a molecular sensor of anti-androgens but also influences the outcome of therapeutic regimen with anti-androgenic drugs via a novel AR-PXR cross-talk. Using 'gain- and loss-of-function' studies, we identified a distinct role of PXR as a potent repressor of AR-regulated transcription. Our study implicates PXR as a key determinant of anti-androgen action since down-regulation of PXR diminishes the potency of the anti-androgenic drugs and enhances transcriptional actions of androgens. In addition, our subcellular localization studies revealed that ligand-activated AR induces nuclear localization of PXR and the two receptors colocalize at discrete sites in nucleus and mitotic chromatin. Finally, we report a distinct antagonist-induced interaction between AR and PXR defining a hitherto unidentified mode of action of AR antagonist. In this perspective, the study may help in designing and development of novel AR antagonists offering improved avenues in prostate cancer therapy.