962 CLUSTERIN KNOCKDOWN ENHANCES ANTITUMOR ACTIVITY OF A NOVEL AKT INHIBITOR, AZD5363, THROUGH INHIBITION OF AUTOPHAGY IN PROSTATE CANCER

Abstract

You have accessJournal of UrologyProstate Cancer: Basic Research V1 Apr 2012962 CLUSTERIN KNOCKDOWN ENHANCES ANTITUMOR ACTIVITY OF A NOVEL AKT INHIBITOR, AZD5363, THROUGH INHIBITION OF AUTOPHAGY IN PROSTATE CANCER Masafumi Kumano, Fan Zhang, Masaki Shiota, Claire Crafter, Barry Davies, Amina Zoubeidi, and Martin Gleave Masafumi KumanoMasafumi Kumano Vancouver, Canada More articles by this author , Fan ZhangFan Zhang Vancouver, Canada More articles by this author , Masaki ShiotaMasaki Shiota Vancouver, Canada More articles by this author , Claire CrafterClaire Crafter Macclesfield, United Kingdom More articles by this author , Barry DaviesBarry Davies Macclesfield, United Kingdom More articles by this author , Amina ZoubeidiAmina Zoubeidi Vancouver, Canada More articles by this author , and Martin GleaveMartin Gleave Vancouver, Canada More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.1061AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Biologically rational co-targeting strategies are increasingly required to circumvent acquired treatment resistance in cancer. Both clusterin (CLU), a stress-induced cytoprotective chaperone, and the AKT signalling pathway, play important roles in castrate resistant prostate cancer (CRPC) progression. While we found that the novel Akt inhibitor, AZD5363, inhibited CRPC progression, CLU and autophagy were induced which may function as cytoprotective responses that undermine anti-cancer effects of Akt inhibition. Since CLU and autophagy are activated by cancer treatment stress as adaptive responses to block treatment-induced cell death, their inhibition may increase cell death in combination with cancer therapy. Recently we found that CLU enhances autophagy, and therefore hypothesize that inhibition of AZD5363-induced autophagic flux using the CLU inhibitor, OGX-011, will synergistically enhance treatment-induced prostate cancer cell death and inhibit tumor growth in vitro and in vivo. METHODS Induction of CLU mRNA and protein levels was measured by real-time RT-PCR and immunoblot assays, while autophagic flux was assessed using expression levels of LC3II and by counting LC3 puncta. Effects of single agent vs combination therapy using AZD5363 +/-OGX-011 were evaluated in vitro on PC3 and LNCaP cell growth and apoptotic rates, and in vivo in athymic mice bearing PC3 xenografts. RESULTS In prostate cancer cells, CLU expression was induced by several autophagy inducers, including serum starvation, rapamycin, and AZD5363. Autophagic flux also increased in parallel with CLU induction. Targeted suppression of CLU using siRNA or OGX-011 inhibited stress-induced autophagy induced by AZD5363 and several other autophagy inducers. OGX-011 synergistically enhanced the activity of AZD5363 on cell growth and apoptosis with increased sub-G1 fraction and PARP cleavage in both PC3 and LNCaP cells. Furthermore, in vivo, OGX-011 combined with AZD5363 significantly inhibited PC3 tumor growth by 60% compared to AZD5363 alone. CONCLUSIONS AZD5363-mediated induction of CLU and autophagy can be attenuated by CLU knockdown. Since OGX-011 and Akt inhibitors are both in clinical development, defining the role of stress-induced autophagy treatment resistance and as an anti-cancer strategy are critical. OGX-011 may serve as a novel inhibitor of stress-induced autophagy in cancer and guide rational co-targeting combination strategies associated with autophagy activation, like AZD5363. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e392 Peer Review Report Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Masafumi Kumano Vancouver, Canada More articles by this author Fan Zhang Vancouver, Canada More articles by this author Masaki Shiota Vancouver, Canada More articles by this author Claire Crafter Macclesfield, United Kingdom More articles by this author Barry Davies Macclesfield, United Kingdom More articles by this author Amina Zoubeidi Vancouver, Canada More articles by this author Martin Gleave Vancouver, Canada More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...