Project description:In castration-resistant prostate cancer (CRPC), clinical response to androgen receptor (AR) antagonists is limited mainly due to AR-variants expression and restored AR signaling. The metabolite spermine is most abundant in prostate and it decreases as prostate cancer progresses, but its functions remain poorly understood. Here, we show spermine inhibits full-length androgen receptor (AR-FL) and androgen receptor splice variant 7 (AR-V7) signaling and suppresses CRPC cell proliferation by directly binding and inhibiting protein arginine methyltransferase PRMT1. Spermine reduces H4R3me2a modification at the AR locus and suppresses AR binding as well as H3K27ac modification levels at AR target genes. Spermine supplementation restrains CRPC growth in vivo. PRMT1 inhibition also suppresses AR-FL and AR-V7 signaling and reduces CRPC growth. Collectively, we demonstrate spermine as an anticancer metabolite by inhibiting PRMT1 to transcriptionally inhibit AR-FL and AR-V7 signaling in CRPC, and we indicate spermine and PRMT1 inhibition as powerful strategies overcoming limitations of current AR-based therapies in CRPC.
Project description:The ligand-activated androgen receptor is a transcription factor that drives prostate cancer growth. Blocking androgen-activation of androgen receptor via androgen deprivation therapy is the default treatment for metastatic prostate cancer. Despite initial remissions, androgen deprivation invariably fails and prostate cancer progresses to castration-recurrent disease, which still relies on aberrantly activated androgen receptor. Alternative approaches are needed to inhibit androgen receptor action in prostate cancer that has failed androgen deprivation therapy. Our laboratory has been exploring the therapeutic potential of a non-canonical androgen receptor signaling mechanism wherein androgen receptor stimulates another transcription factor, Serum Response Factor. Serum Response Factor-mediated androgen receptor action correlates with prostate cancer progression and is enriched in castration-recurrent prostate cancer. Inhibiting Serum Response Factor-dependent androgen receptor action may be an effective treatment strategy following failure of androgen deprivation therapy but remains poorly understood. We have recently isolated UPF1 and RCOR1 as putative novel mediators of Serum Response Factor-dependent androgen receptor action. Here, we perform RNA-Seq assays to determine the contribution of UPF1 and RCOR1 to the androgen response of prostate cancer cells.