Abstract
You have accessJournal of UrologyProstate Cancer: Basic Research III1 Apr 2010376 HEDGEHOG/GLI SUPPORTS ANDROGEN SIGNALING IN ANDROGEN DEPRIVED AND ANDROGEN INDEPENDENT PROSTATE CANCER CELLS Mengqian Chen, Elina Levina, Matthew Tanner, Alexandre de la Taille, Francis Vacherot, Stephane Terry, and Ralph Buttyan Mengqian ChenMengqian Chen Albany, NY More articles by this author , Elina LevinaElina Levina Albany, NY More articles by this author , Matthew TannerMatthew Tanner Albany, NY More articles by this author , Alexandre de la TailleAlexandre de la Taille Creteil, France More articles by this author , Francis VacherotFrancis Vacherot Creteil, France More articles by this author , Stephane TerryStephane Terry Creteil, France More articles by this author , and Ralph ButtyanRalph Buttyan Albany, NY More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.444AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Hedgehog (Hh) is a developmental cell signaling pathway that regulates Gli-mediated transcription. Previously we showed that androgen deprivation induces expression of Hh ligands and awakens autocrine Hh signaling in prostate cancer cells. Here we evaluated the effect of inhibitors of autocrine Hh or of hyperactive Gli on androgen signaling activity and cell growth in androgen deprived (AD) and androgen independent (AI) prostate cancer cells. METHODS LNCaP and AI variants (LNCaP-AI, C4-2B or LN3) or VCaP cells were cultured in androgen-free medium in the presence or absence of the Hh inhibitor, cyclopamine. Smoothened (Smo) siRNA was transfected into cells to mimic cyclopamine action. Gli1 and Gli2 expression vectors were transfected into LNCaP cells to mimic hyperactivity of Hh. Expression of androgen regulated genes were evaluated by real-time reverse-transcriptase PCR (qPCR). Luciferase (luc) reporter vectors promoted by the androgen-responsive probasin (PRB) or PGC gene promoters were transfected into cells to serve as a surrogate marker of AR activity. Cell growth was measured by cell counting and by a WST-assay. Human 293-FT cells were co-transfected with AR and myc-tagged Gli2 to identify interaction between AR and Gli2 by co-immunoprecipitation with anti-AR or anti-myc antibodies. RESULTS Cyclopamine treatment dose-dependently downregulated expression of KLK2, KLK3 and PGC and upregulated androgen-repressed SHH expression in all cell lines. Cyclopamine also downregulated expression of luc from PRB or PGC promoters. These responses were mimicked by Smo but not by control siRNAs. Gli1 and Gli2 overexpression in LNCaP cells upregulated KLK2, KLK3 and PGC expression in a bicalutamide-independent manner. Gli1 and Gli2 overexpression also confered AI growth on LNCaP cells. Gli2 co-immunoprecipitates with AR from 293-FT cell extracts. CONCLUSIONS Inhibition of autocrine Hh suppressed residual androgen signaling in AD and AI prostate cancer cells and blocked AI growth. Overexpression of Gli increased residual androgen signaling and conferred AI growth. We conclude that autocrine Hh signaling supports androgen action under low/no androgen conditions. Gli2 protein interacts with AR and this interaction might represent the point of cross-talk between Hh and androgen signaling in prostate cancer. © 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e149 Peer Review Report Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Mengqian Chen Albany, NY More articles by this author Elina Levina Albany, NY More articles by this author Matthew Tanner Albany, NY More articles by this author Alexandre de la Taille Creteil, France More articles by this author Francis Vacherot Creteil, France More articles by this author Stephane Terry Creteil, France More articles by this author Ralph Buttyan Albany, NY More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...
Highlights
Castration resistant prostate cancer (CRPC) develops as a consequence of hormone therapies used to deplete androgens in advanced prostate cancer patients
All experiments were done using a medium that was depleted for androgens that could be re-supplemented with androgen (R1881) to mimic androgen-stimulated conditions
For parental LNCaP cells grown in androgen supplemented medium (+R1881), the presence of cyclopamine had no significant effects on the expression of four model androgen-regulated genes; KLK2, KLK3 [PSA] and PGC, or SHH that is repressed by androgen (Figure 1A)
Summary
Castration resistant prostate cancer (CRPC) develops as a consequence of hormone therapies used to deplete androgens in advanced prostate cancer patients. Cells [6,7,8] and a variety of mechanisms may account for residual androgen signaling in a low androgen environment These include expression of variant forms of androgen receptor (AR) that are transcriptionally active without ligand [9,10], acquisition of an ability to endogenously synthesize androgens by the tumor cells themselves [11,12] or activation of aberrant AR transcriptional activity through cross-talk with alternate signaling pathways [6,13]. We describe findings that suggest that inhibitors of the Hedgehog/Gli signaling pathway, currently in clinical testing for a variety of cancers, might have a role for the treatment of castration resistant prostate cancer due to an ability to suppress reactivated androgen signaling in tumor cells
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