Abstract 3250: Computational drug repositioning and biochemical validation of piperlongumine as a potent therapeutic agent for neuroendocrine prostate cancer

Introduction and Objectives: Neuroendocrine prostate cancer (NEPC) is a highly lethal and drug-resistant variant of prostate cancer (PCa). We have used a genomics-based drug-repositioning approach and identified compounds with therapeutic activity against NEPC. One of the compounds- piperlongumine (PL) is a natural product constituent of the fruit of the Long pepper (Piper longum). The efficacy of this drug was tested in the NEPC cell line model NCI-H660 and compared to several other PCa cell lines in a modified WST-1 assay. Pre-clinical testing in mouse xenograft models of NEPC was also undertaken. Finally, the ability of piperlongumine to inhibit p-STAT3 signaling and promote apoptosis was measured by western blot analyses. Methods: PCa cell lines (LNCaP, 22Rv1, Du145, PC3, H660 and RWPE) were grown in complete media (RPM1 10%FBS, Advanced DMEM 5%FBS or Keratinocyte-SFM) and treated with piperlongumine for 3 or 7 days. IC50 values were generated from WST assay data using Prism6. Nude mice (n=5) were injected with 1.5x106 H660 cells on each flank, and intraperitoneally administered with either 2.5mg/kg PL (n=3) or DMSO (n=2) daily for 3 weeks after tumors formed 200mm3 in volume. Tumor volume was measured daily with calipers. Western blot analyses were performed on protein lysates extracted from tumors and PCa cells treated with 0-10 μM of drug. Results: PL was highly effective in inhibiting the growth of H660 cells (IC50 = 0.4 μM) compared to LNCaP, 22Rv1, Du145, PC3, and RWPE cells. This was consistent with an increased level of cPARP1 in H660 cells when compared to other prostate cancer cell lines. On average, the growth rate of untreated tumors was 2.7 times greater than those treated with PL. Similar to previous reports suggesting PL to inhibit STAT3 activity, treated H660 cells exhibited inhibition of STAT3 phosphorylation. Conclusions: Using computational drug repositioning approaches we have identified several lead compounds for NEPC. One of the compound piperlongumine, a water-soluble plant product with no known side effects inhibits the growth of the highly drug-resistant NEPC cell line H660. Source of Funding: Deane Prostate Health, Icahn School of Medicine at Mount Sinai. Both Shalini S Yadav and Kamlesh K Yadav are supported by the Prostate Cancer Foundation Young Investigator Awards. Research in Dudley9s lab is supported by grants from National Institutes of Health R01 DK098242 and U54 CA189201. Note: This abstract was not presented at the meeting. Citation Format: Kamlesh Kumar Yadav, Khader Shameer, Ben Readhead, Jennifer A. Stockert, Cordelia Elaiho, Shalini S. Yadav, Benjamin S. Glicksberg, Kipp W. Johnson, Christine Becker, Andrew Kasarskis, Ashutosh K. Tewari, Joel T. Dudley. Computational drug repositioning and biochemical validation of piperlongumine as a potent therapeutic agent for neuroendocrine prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3250. doi:10.1158/1538-7445.AM2017-3250