ARv7 represses tumor suppressors genes in castration-resistant prostate cancer [ChIP-Seq]

Endocrine therapies in prostate cancer (PCa) treatment block androgen receptor (AR) function, but are palliative as tumors progress to a lethal, castration-resistant state (CRPC). CRPC remains dependent on AR signaling, which can act through the full-length AR (ARfl) or constitutively active splice variants, e.g. ARv7. We show here that both ARfl and ARv7 bind to the same genomic region and heterodimerize in a CRPC cell line model, but regulate distinct transcriptomes. ARv7, unlike ARfl, preferentially represses transcription and demonstrates an increased affinity for co-repressors, decreased chromatin residence time and lower dependence on FOXA1 binding. We identified a group of ARv7-repressed genes, including the UDP-galactosyltransferase B4GALT1 that are down-regulated during PCa progression and important for CRPC growth. In conclusion, we propose that ARv7 acts as a transcriptional repressor of genes that limit proliferation, a function that should be targeted in CRPC patients. Overall design: ChIP-seq from shRNA-mediated knock-down experiments in prostate cancer cell lines