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J Biol Chem. 2014 Sep 19;289(38):26417-29. doi: 10.1074/jbc.M114.553818. Epub 2014 Aug 1.

Selectively targeting the DNA-binding domain of the androgen receptor as a prospective therapy for prostate cancer.

Author information

1
From the Vancouver Prostate Centre, University of British Columbia, Vancouver, British Columbia V6H 3Z6, Canada and kdalal@prostatecentre.com.
2
From the Vancouver Prostate Centre, University of British Columbia, Vancouver, British Columbia V6H 3Z6, Canada and.
3
the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455.

Abstract

The androgen receptor (AR) is a transcription factor that has a pivotal role in the occurrence and progression of prostate cancer. The AR is activated by androgens that bind to its ligand-binding domain (LBD), causing the transcription factor to enter the nucleus and interact with genes via its conserved DNA-binding domain (DBD). Treatment for prostate cancer involves reducing androgen production or using anti-androgen drugs to block the interaction of hormones with the AR-LBD. Eventually the disease changes into a castration-resistant form of PCa where LBD mutations render anti-androgens ineffective or where constitutively active AR splice variants, lacking the LBD, become overexpressed. Recently, we identified a surfaced exposed pocket on the AR-DBD as an alternative drug-target site for AR inhibition. Here, we demonstrate that small molecules designed to selectively bind the pocket effectively block transcriptional activity of full-length and splice variant AR forms at low to sub-micromolar concentrations. The inhibition is lost when residues involved in drug interactions are mutated. Furthermore, the compounds did not impede nuclear localization of the AR and blocked interactions with chromatin, indicating the interference of DNA binding with the nuclear form of the transcription factor. Finally, we demonstrate the inhibition of gene expression and tumor volume in mouse xenografts. Our results indicate that the AR-DBD has a surface site that can be targeted to inhibit all forms of the AR, including enzalutamide-resistant and constitutively active splice variants and thus may serve as a potential avenue for the treatment of recurrent and metastatic prostate cancer.

KEYWORDS:

Androgen Receptor; DNA-binding Protein; Drug Discovery; Nuclear Receptor; Prostate Cancer

PMID:
25086042
PMCID:
PMC4176249
DOI:
10.1074/jbc.M114.553818
[Indexed for MEDLINE]
Free PMC Article

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