Androgen Receptor Gene Expression in Prostate Cancer is Directly Suppressed by the Androgen Receptor Through Recruitment of Lysine Specific Demethylase 1

Androgen receptor (AR) is reactivated in castration resistant prostate cancer (CRPC) through mechanisms including marked increases in AR gene expression. We identify an enhancer in the AR second intron contributing to increased AR expression at low androgen levels in CRPC. Moreover, at increased androgen levels the AR binds this site and represses AR gene expression through recruitment of lysine specific demethylase 1 (LSD1) and H3K4me1,2 demethylation. AR similarly represses expression of multiple genes mediating androgen synthesis, DNA synthesis and proliferation, while stimulating genes mediating lipid and protein biosynthesis. Androgen levels in CRPC appear adequate to stimulate AR activity on enhancer elements, but not on suppressor elements, resulting in increased expression of AR and AR repressed genes that contribute to cellular proliferation. Custom Agilent 44K whole human genome expression oligonucleotide microarrays were used to profile pre-castrated androgen dependent, 4d-post-castrated, and relapsed castration resistant VCaP xenograft tumors in 3 mice. Total RNA was isolated and amplified prior to hybridization against a common reference pool of prostate tumor cell lines.