Analysis of active enhancers and direct androgen receptor target genes in VCaP prostate cancer cells

Androgen receptor (AR) is typically overexpressed in castration-resistant prostate cancer (CRPC). CRPC-derived VCaP cells display an excessive number of chromatin AR-binding sites (ARBs). This study analyzed direct transcription programs of the AR, the prevalence of AR enhancers and the transcriptional regulators involved in the regulation of at the enhancer regions. The analysis utilized global nuclear run-on sequencing (GRO-seq). The GRO-seq data were integrated with the ARB and VCaP cell-specific transcription factor-binding data. Androgen in 30 min activated and repressed transcription of a large number of genes including novel AR targets IGF-1 receptor and EGF receptor. GRO-seq analysis also revealed that only a fraction of the ARBs resides at functional enhancers. Activation of AR bound enhancers was most potent at the sites that also bound PIAS1, ERG and HDAC3. Our genome-wide data provide new insights how AR can directly control growth-signaling pathways in CPRC cells. Overall design: ChIP-seq samples were collected from cells treated with vehicle (ethanol, EtOH) or 10 nM R1881 (synthetic androgen methyltrienolone). IgG sample was collected from EtOH- and R1881-treated cells and used as background control. Biological duplicate samples of the AR (R1881-treated) and CTCF (vehicle- and R1881-treated) ChIP-seq samples were analyzed by using Illumina HiSeq 2000 platform 1.9. Single IgG and H3K9me3 (R1881-treated) samples were analyzed with the same platform. GRO-seq was used to determine androgen-induced changes in nascent transcription in VCaP and LNCaP cells.

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Toropainen S, Niskanen EA, Malinen M, Sutinen P, Kaikkonen MU, Palvimo JJ