Androgen receptor (AR) inhibitors are used to treat multiple human diseases, including hirsutism, benign prostatic hypertrophy, and prostate cancer, but all available anti-androgens target only ligand binding, either by reduction of available hormone or by competitive antagonism. New strategies are needed, and could have an important impact on therapy. One approach could be to target other cellular mechanisms required for receptor activation. In prior work, we used a cell-based assay of AR conformation change to identify non-ligand inhibitors of AR activity. Here, we characterize 2 compounds identified in this screen: pyrvinium pamoate, a Food and Drug Administration-approved drug, and harmol hydrochloride, a natural product. Each compound functions by a unique, non-competitive mechanism and synergizes with competitive antagonists to disrupt AR activity. Harmol blocks DNA occupancy by AR, whereas pyrvinium does not. Pyrvinium inhibits AR-dependent gene expression in the prostate gland in vivo, and induces prostate atrophy. These results highlight new therapeutic strategies to inhibit AR activity.
Conflict of interest statement
Conflict of interest statement: Given the potential utility of pyrvinium and harmol as therapeutic agents, the University of California, San Francisco, has filed a novel use patent that claims these compounds. J.O.J. and M.I.D. are co-inventors on this patent, and will stand to profit if it is issued. To the extent that publication of this manuscript will increase the value of this patent, or the likelihood that it will be out-licensed, J.O.J. and M.I.D. have a potential conflict of interest.
By Jeremy O Jones, Eric C Bolton, Yong Huang, Clementine Feau, R Kiplin Guy, Keith R Yamamoto, Byron Hann & Marc I Diamond