Phenethyl isothiocyanate inhibits androgen receptor-regulated transcriptional activity in prostate cancer cells through suppressing PCAF

Scope: Androgen receptor (AR) signaling is critical for all aspects of prostate growth and tumorigenesis. The glucosinolate-derived phenethyl isothiocyanate (PEITC) has recently been demonstrated to reduce the risk of prostate cancer (PCa) and inhibit PCa cell growth. We previously reported that p300/CBP-associated factor (PCAF), a co-regulator for AR, is upregulated in PCa cells through suppression of the mir-17 gene. Here, we assessed the effects of PEITC on PCAF expression and AR-regulated transcriptional activity in PCa cells. Methods and results: Using AR-responsive LNCaP cells, we observed the inhibitory effects of PEITC on the dihydrotestosterone-stimulated AR transcriptional activity and cell growth of PCa cells. Interestingly, overexpression of PCAF attenuated the inhibitory effects of PEITC on dihydrotestosterone-stimulated AR transcriptional activity. Expression of PCAF was upregulated in PCa cells through suppression of miR-17. PEITC treatment significantly decreased PCAF expression and promoted transcription of miR-17 in LNCaP cells. Functional inhibition of miR-17 attenuated the suppression of PCAF in cells treated by PEITC. Conclusion: Our results indicate that PEITC inhibits AR-regulated transcriptional activity and cell growth of PCa cells through miR-17-mediated suppression of PCAF, suggesting a new mechanism by which PEITC modulates PCa cell growth.