Mp05-13 Testosterone Decreases Programmed Death Ligand-1 (Pdl-1) Level in Prostate Cancer

You have accessJournal of UrologyProstate Cancer: Basic Research & Pathophysiology I (MP05)1 May 2024MP05-13 TESTOSTERONE DECREASES PROGRAMMED DEATH LIGAND-1 (PDL-1) LEVEL IN PROSTATE CANCER Sanjeev Shukla, Teruko Osumi, Mohammed Al-Toubat, Samuel Serrano, and KC Balaji Sanjeev ShuklaSanjeev Shukla , Teruko OsumiTeruko Osumi , Mohammed Al-ToubatMohammed Al-Toubat , Samuel SerranoSamuel Serrano , and KC BalajiKC Balaji View All Author Informationhttps://doi.org/10.1097/01.JU.0001008740.27639.cc.13AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Whereas immune checkpoint inhibitors (ICI) PDL-1 and PD-1 monoclonal antibodies are effective in several solid human cancers, ICI is ineffective in most men with advanced prostate cancer (APC). The expression of PDL-1 is a well-studied classical biomarker of resistance to ICI. Most men with APC are treated with androgen deprivation therapy (ADT), which is known to be immunosuppressive. We hypothesized that ADT contributes to inefficacy of ICI and testosterone replacement despite castration would improve sensitivity to ICI in men with APC. In parallel, we discovered that Protein Kinase D (PKD) is a novel androgen sensitive family of proteins and shown to be involved in PDL-1 expression. PKD family has 3 isoforms, and the charter member PKD1 interacts and putatively phosphorylates Cyclin Dependent Kinase 12 (CDK12). CDK12 mutated (CDK12 m) prostate cancer (PC) is a recognized distinct aggressive variant of PC. Therefore, we studied the effect of ADT and testosterone replacement on PDL-1 expression, and whether PKD/CDK12 signaling may have a role in testosterone induced suppression of PDL-1. METHODS: We used state of the art molecular and gene editing tools in regularly authenticated phenotypically characterized PC cell lines, cell viability assay, western blot, bimolecular fluorescence complementation (BIFC) assay, site directed mutagenesis, RT-PCR, Compound 10 and THZ 531, a selective PKD and CDK12 inhibitors respectively. In addition, we mined publicly available databases for gene expression profiling. We used a patient derived xenograft (PDX) mice model to study tolerability of C10 in vivo for potential pre-clinical development. RESULTS: ADT and testosterone replacement increased and decreased PDL-1 expression and protein levels respectively in APC cell lines. Mining of RNA-sequencing data from the TCGA consortium database confirmed significantly increased PDL-1 expression in castration resistant prostate cancer (CRPC) presumably due to ADT compared to non-metastatic disease. Similar in silico mining also demonstrated that PKD1 and CDK12 are in the same signaling pathway. Immunoprecipitation and BIFC demonstrated that PKD1 and CDK12 directly interact. Mutation of PKD1 putative phosphorylation sites in CDK12 s681a and s681a/s685a resulted in decreased CDK12 substrate phosphorylation of RNA polymerase Ii heptapeptide repeats YSPTSPS at S2 and 5 and decreased global gene expression including key DNA damage and oncogenes. Testosterone treatment of PC cells altered the protein levels of PKD isoforms. Treatment of PC cells with C10 or THZ 531 decreased cell viability, C10 decreased PDL-1 protein levels and C10 was well tolerated in PDX mice. CONCLUSIONS: Testosterone replacement reverses castration induced increases in PDL-1 levels. Mechanistically, PKD/CDK12 signaling may be involved in testosterone induced suppression of PDL-1. The findings could be leveraged for improving efficacy of ICI in men with APC. Source of Funding: N/A © 2024 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 211Issue 5SMay 2024Page: e47 Advertisement Copyright & Permissions© 2024 by American Urological Association Education and Research, Inc.Metrics Author Information Sanjeev Shukla More articles by this author Teruko Osumi More articles by this author Mohammed Al-Toubat More articles by this author Samuel Serrano More articles by this author KC Balaji More articles by this author Expand All Advertisement PDF downloadLoading ...