Stilbene induced inhibition of androgen receptor dimerization: implications for AR and AR?LBD-signalling in human prostate cancer cells.

ABSTRACT:

Background

Advanced castration resistant prostate cancer (CRPC) is often characterized by an increase of C-terminally truncated, constitutively active androgen receptor (AR) variants. Due to the absence of a ligand binding domain located in the AR-C-terminus, these receptor variants (also termed AR?LBD) are unable to respond to all classical forms of endocrine treatments like surgical/chemical castration and/or application of anti-androgens.

Methodology

In this study we tested the effects of the naturally occurring stilbene resveratrol (RSV) and (E)-4-(2, 6-Difluorostyryl)-N, N-dimethylaniline, a fluorinated dialkylaminostilbene (FIDAS) on AR- and AR?LBD in prostate cancer cells. The ability of the compounds to modulate transcriptional activity of AR and the AR?LBD-variant Q640X was shown by reporter gene assays. Expression of endogenous AR and AR?LBD mRNA and protein levels were determined by qRT-PCR and Western Blot. Nuclear translocation of AR-molecules was analyzed by fluorescence microscopy. AR and AR?LBD/Q640X homo-/heterodimer formation was assessed by mammalian two hybrid assays. Biological activity of both compounds in vivo was demonstrated using a chick chorioallantoic membrane xenograft assay.

Results

The stilbenes RSV and FIDAS were able to significantly diminish AR and Q640X-signalling. Successful inhibition of the Q640X suggests that RSV and FIDAS are not interfering with the AR-ligand binding domain like all currently available anti-hormonal drugs. Repression of AR and Q640X-signalling by RSV and FIDAS in prostate cancer cells was caused by an inhibition of the AR and/or Q640X-dimerization. Although systemic bioavailability of both stilbenes is very low, both compounds were also able to downregulate tumor growth and AR-signalling in vivo.

Conclusion

RSV and FIDAS are able to inhibit the dimerization of AR and AR?LBD molecules suggesting that stilbenes might serve as lead compounds for a novel generation of AR-inhibitors.

SUBMITTER: Streicher W 

PROVIDER: S-EPMC4041728 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature