You have accessJournal of UrologyProstate Cancer: Basic Research V1 Apr 2015MP66-14 IDENTIFYING NOVEL NUCLEAR TRANSPORTER OF AR AND AR(VARIANT) IN CRPC CELLS: POTENTIAL IMPLICATIONS IN THERAPY Mohammad Saleem, Badrinath Konety, Aijaz Parray, Hifzur Siddique, Robert Matusik, Mikihik Naito, and Alyssa Langfald Mohammad SaleemMohammad Saleem More articles by this author , Badrinath KonetyBadrinath Konety More articles by this author , Aijaz ParrayAijaz Parray More articles by this author , Hifzur SiddiqueHifzur Siddique More articles by this author , Robert MatusikRobert Matusik More articles by this author , Mikihik NaitoMikihik Naito More articles by this author , and Alyssa LangfaldAlyssa Langfald More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.2367AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The dismal outcome of androgen receptor (AR)-targeted therapies in Castration-resistant prostate cancer (CRPC) has been largely attributed to the activation of AR-variants in tumor cells. Although the nuclear carrier of full-length AR (ARFL) is known, the mechanism underlying the nuclear translocation of AR-variant (ARv) under castration conditions is not completely understood. Understanding such a mechanism could form the basis of future therapies to treat CRPC disease. We for the first time show that “cFLIP” protein acts a shuttling protein between cytoplasm and nucleus of cells, and acts as a conduit for ARFL and ARv7 in CRPC cells. METHODS We used human and mouse prostatic tissues, cell-models, immunoblot, immunoprecipitation, immunohistochemical, transfections, confocal-microscopy and luciferase-reporter techniques. RESULTS Previously, cFLIP was identified as an androgen-responsive gene. However, we show that cFLIP expression is increased in androgen-independent CaP cells. We provide evidence that (i) cFLIP-expressing CRPC cells exhibit higher proliferative index than cFLIP-deficient counterparts and (ii) cFLIP expression is high in prostatic tissues of castrated (ARR2.IκB-Myc) transgenic mice. The significance of cFLIP as an upstream of AR could be ascertained from the finding that suppressing cFLIP could decrease PSA levels and transcriptional activities of ARFL and ARv7 in CRPC cells. These data prompted to further investigate the correlation between Cflip, ARFL and ARv7. We show that cFLIP forms a complex with ARv-7 and ARFL in CRPC cells. We observed higher levels of cFLIP/ARv7 complex in nuclei than in cytoplasm suggesting the possibility of cFLIP as a protein-carrier. Using transfections with cFLIP-Long, cFLIP-short-variant and mutants (cFLIPL-435mt/472mt/439mt), two sequences on C-terminus were identified for nuclear translocation that confirmed its protein-transporter property. These data were validated in PC3 cells (in which ARv7 was ectopically expressed). Next, we observed that β-catenin is required for complex formation and subsequent nuclear translocation of cFLIP/ARv7 in cells. Finally, using a xenograft mouse model, we established the significance of cFLIP/ARv7 complex as a therapeutic target and show that simultaneous targeting (by using nanoparticle-loaded cFLIP-siRNA + ARv7-siRNA) significantly inhibits CRPC-type tumor growth and improves the outcome of docetaxel therapy. We also identified a novel inhibitor of cFLIP/ARv. CONCLUSIONS We identified a novel therapeutic approach of treating CRPC. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e820-e821 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Mohammad Saleem More articles by this author Badrinath Konety More articles by this author Aijaz Parray More articles by this author Hifzur Siddique More articles by this author Robert Matusik More articles by this author Mikihik Naito More articles by this author Alyssa Langfald More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...