The BET-inhibitor PFI-1 diminishes AR/AR-V7 signaling in prostate cancer cells

The bromodomain and extra-terminal (BET) family of proteins provides a scaffolding platform for the recruitment and tethering of transcription factors to acetylated chromatin, thereby modulating gene expression. In this study, we evaluated the efficacy of the BET-inhibitor PFI-1 to diminish AR/AR-V7 signaling and proliferation in castration-resistant prostate cancer cells.

Prostate-specific antigen and androgen receptor (AR) protein were quantified by means of two commercial ELISAs. Transactivation of the AR, AR-V7 and Q641X was determined by reporter gene assays. Cell proliferation was measured using a colorimetric MTT-assay.

PFI-1 dose-dependently inhibited transactivation of full-length AR (non- mutated, i.e., wild-type or point-mutated/promiscuous forms) without affecting their cellular protein levels. Moreover, PFI-1 was active against C-terminally truncated constitutively active ARs like AR-V7 and Q641X. Prostate cancer cells exhibiting a transcriptionally active AR-signaling complex (LNCaP, 22Rv1) were more susceptible to the growth-inhibitory effects than the AR-negative PC-3 cells.

The quinazolinone PFI-1 is a highly efficient inhibitor of AR-signaling-competent prostate cancer cells in vitro. PFI-1 could serve as a lead compound for the development of new therapeutics able to block AR/AR-V7 signaling in advanced prostate cancer.

World journal of urology. 2018 Jun 22 [Epub ahead of print]

Marie C Hupe, M Raschid Hoda, Friedemann Zengerling, Sven Perner, Axel S Merseburger, Marcus V Cronauer

Department of Urology, University Hospital Schleswig-Holstein, Campus Lübeck, Ratzeburger Allee 160, 23538, Lübeck, Germany., Department of Urology, University of Ulm, 89075, Ulm, Germany., Pathology of the University Hospital Schleswig-Holstein, Campus Lübeck and Research Center Borstel, Leibniz Center for Medicine and Biosciences, Borstel, Germany., Department of Urology, University Hospital Schleswig-Holstein, Campus Lübeck, Ratzeburger Allee 160, 23538, Lübeck, Germany. .

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