MP37-01 GLI3 EXPRESSION INFLUENCES ANDROGEN RECEPTOR ACTIVITY AND FUNCTION IN ANDROGEN GROWTH-INDEPENDENT PROSTATE CANCER

Abstract

You have accessJournal of UrologyProstate Cancer: Basic Research I1 Apr 2015MP37-01 GLI3 EXPRESSION INFLUENCES ANDROGEN RECEPTOR ACTIVITY AND FUNCTION IN ANDROGEN GROWTH-INDEPENDENT PROSTATE CANCER Na Li, Sarah Truong, Mannan Nouri, and Ralph Buttyan Na LiNa Li More articles by this author , Sarah TruongSarah Truong More articles by this author , Mannan NouriMannan Nouri More articles by this author , and Ralph ButtyanRalph Buttyan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.1264AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Progression to castrate resistant prostate cancer (CRPC) is associated with hyperactive androgen receptor (AR) signaling and with a shift of AR transcriptional targeting towards genes that regulate the G2/M-phase of cell growth (M phase Regulatory Genes [MRGs]). Previously, we showed that Gli2, a member of the Gli transcription factor family that mediates Hedgehog signaling, can bind and co-activate full-length [FL-] and splice truncated [t-] ARs. Here we show that Gli3 also has AR co-activation activity and provide evidence that Gli3 specifically affects AR target gene selection in androgen growth-independent (AI) prostate cancer (PCa) cells. METHODS Gli3 or AR were immunoprecipitated (IP) from PCa cell extracts and IP proteins were evaluated for co-IP of the non-precipitated protein by Western blot. Gli3 was tested for FL- and t-AR co-activation using an AR reporter strategy or by transfection into FL- or t-AR expressing PCa cell lines. Expression of Gli1/2 or 3 in a variety of PCa cell lines was measured by qPCR. Processing of Gli3 protein to its repressor form was evaluated in extracts of LNCaP or LNCaP-AI cells by Western blot. Expression of differentiation genes [KLK2 and KLK3] or MRGs [UBE2C, CDK1, CDC20 and CCNA2] in LNCaP and LNCaP-AI cells were measured by qPCR in control or stable Gli3 overexpressing cells or in cells treated with Gli inhibitors (GANT-61 and HPI-1) or Gli3 siRNA. Growth of LNCaP-AI cells was measured after treatment with Gli inhibitors or Gli3 siRNA and compared to vehicle- or control-siRNA treated cells. RESULTS Gli3 co-IPs with AR from PCa cell extracts and it co-activated FL- or t-ARs in all our assays. Gli3 mRNA is expressed at 100-times or higher levels than Gli1 or 2 in all PCa cell lines assayed. Gli3 protein was processed to its repressor form in LNCaP cells but not in LNCaP-AI cells. Exogenous Gli3 overexpression in LNCaP-AI cells that naturally overexpress MRGs reduced expressions of differentiation genes while further increased expressions of MRGs. Likewise, treatment of LNCaP-AI cells with Gli inhibitors or Gli3 siRNA significantly suppressed their growth and increased expressions of differentiation genes and lowered MRG gene expressions. CONCLUSIONS Gli3 can bind and co-activate AR. It is naturally expressed at much higher levels in PCa cell lines than its homologues (Gli1/2) and the Gli3 protein is differentially processed in androgen dependent vs androgen independent LNCaP cells. Finally, Gli3 expression and activity affects selection of AR transcription targets in a manner that supports androgen independent growth. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e437-e438 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Na Li More articles by this author Sarah Truong More articles by this author Mannan Nouri More articles by this author Ralph Buttyan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...