Increasing evidence suggests that AR (androgen receptor) acetylation is critical for prostate cancer cell growth. In the present study, we identified Pro-B3 (procyanidin B3) as a specific HAT (histone acetyltransferase) inhibitor. Pro-B3 selectively inhibited the activity of HATs, but not other epigenetic enzymes. Pro-B3 substantially inhibited the p300-mediated AR acetylation, both in vitro and in vivo. Pro-B3 inhibited both p300-dependent and agonist-induced AR transcription. We demonstrate that the p300-mediated AR acetylation is critical for the hormone responsiveness of AR. Interestingly, B3 treatment efficiently enhanced the antagonist activity of flutamide through suppression of p300 HAT activity, demonstrating that relative p300 activity is critical for the antagonist action. Finally, Pro-B3 treatment inhibited acetylation-dependent prostate cell proliferation and expression of cell-cycle control genes, subsequently increasing cell death, indicating the functional importance of AR acetylation for prostate cancer cell growth.
Key words: acetylation, androgen receptor, histone acetyltransferase, procyanidin b3, prostate cancer.
Abbreviations used: aa, amino acids; AR, androgen receptor; ARE, androgen-response element; CBP, CREB (cAMP-response-element-binding protein)-binding protein; ChIP, chromatin immunoprecipitation; DHT, dihydrotestosterone; DTT, dithiothreitol; EGCG, epigallocatechin-3-gallate; FBS, fetal bovine serum; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; GFP, green fluorescent protein; GST, glutathione transferase; HAT, histone acetyltransferase; HATi, HAT inhibitor(s); HDAC, histone deacetylase; HEK, human embryonic kidney; HMT, histone methyltransferase; IP, immunoprecipitation; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide; NE, nuclear extract; PCAF, p300/CBP-activating factor; Pro-B3, procyanidin B3; PSA, prostate-specific antigen; RT, real-time; siRNA, small interfering RNA.
1These authors contributed equally to the present study.
2Correspondence may be addressed to either of these authors (email email@example.com or firstname.lastname@example.org).
Received 2 July 2010/29 September 2010; accepted 18 October 2010
Published as BJ Immediate Publication 18 October 2010, doi:10.1042/BJ20100980
© The Authors Journal compilation © 2011 Biochemical Society