Androgen receptor overexpression alters binding dynamics of the receptor to chromatin and chromatin structure

BACKGROUND Castration-resistant prostate cancers (CRPCs) overexpress often androgen receptor (AR). Here, we investigated the effect of AR overexpression on the dynamics of AR loading and RNA polymerase II (RNA Pol II) recruitment to chromatin. Acetylation of histone 3 (AcH3) on lysines 9 and 14 (K9 and K14) was also studied. METHODS We used an LNCaP-based AR overexpression cell line model that includes a control line and two sublines, LNCaP-ARmo and LNCaP-ARhi, which overexpress AR twofold to threefold and fourfold to fivefold, respectively. Cells were exposed to 1 or 100?nM of dihydrotestosterone (DHT). Chromatin immunoprecipitation (ChIP) on the promoters and enhancers of prostate specific antigen (PSA) and transmembrane protease, serine 2 (TMPRSS2) genes was performed. qRT-PCR was used to measure the levels of PSA and TMPRSS2 transcripts. RESULTS Upon stimulation with 1?nM DHT, AR and RNA Pol II were recruited onto PSA and TMPRSS2 enhancer regions to a greater extent (P?