MP83-07 N-TERMINAL TARGETING OF ANDROGEN RECEPTOR BY EPI-001 IN COMBINATION WITH AUTOPHAGY INHIBITORS ENHANCES THE ANTI-TUMOR EFFECT IN LNCAP PROSTATE CANCER CELLS

Abstract

You have accessJournal of UrologyProstate Cancer: Basic Research & Pathophysiology II1 Apr 2017MP83-07 N-TERMINAL TARGETING OF ANDROGEN RECEPTOR BY EPI-001 IN COMBINATION WITH AUTOPHAGY INHIBITORS ENHANCES THE ANTI-TUMOR EFFECT IN LNCAP PROSTATE CANCER CELLS Benedikt Kranzbühler, Souzan Salemi, Tullio Sulser, and Daniel Eberli Benedikt KranzbühlerBenedikt Kranzbühler More articles by this author , Souzan SalemiSouzan Salemi More articles by this author , Tullio SulserTullio Sulser More articles by this author , and Daniel EberliDaniel Eberli More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.2575AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Multiple androgen receptor (AR) dependent and independent resistance mechanisms limit the efficacy of current castration resistant prostate cancer (CRPC) treatment modalities. EPI-001 is a novel N-terminal domain (NTD) binding AR targeting component with the promising ability to block constitutively active splice variants; a major resistance mechanism in CRPC. Autophagy a conserved lysosomal degradation pathway, is a survival mechanism in cells exposed to anti-cancer treatment. We hypothesized that also a promising NTD-AR treatment may lead to up-regulation of autophagy, which can be targeted by a combination therapy with autophagy inhibitors. METHODS The human prostate cancer cell line LNCaP was cultured in steroid-free medium. Cells were treated with different concentrations of EPI-001 (10, 25, 50uM) and in combination with autophagy inhibitors chloroquine (CHQ, 20uM) or 3-methyladenine (3MA, 5mM). Viability was assessed by WST-1-assays after 1, 3 and 7 days. AnnexinV and Propidium Iodide were used to measure apoptosis and necrosis on day 7 after treatment. Autophagic activity was monitored on protein levels by western blot (WB) and immunocytochemistry for the expression of LC3-I/II, Atg5 and Beclin1. In addition, autophagosome increase was detected by Autodot staining. RESULTS Treatment with EPI-001 resulted in a dose dependent reduction of cell viability up to 50% with 50uM EPI-001 on day 7. At the same time apoptosis increased by 11.53% and necrosis by 3.74% compared to the control. Combination of 50 uM EPI-001 with autophagy inhibitors led to a further significant reduction of cell viability up to 40% for CHQ and 28% for 3MA. Assessment of autophagy levels in EPI-001 treated cells by WB showed an increase of LC3-II in a dose dependent manner. No Change in Beclin1 expression was seen. Immuncytochemistry detected a significant increase of Atg5 and pronounced LC3-II punctuation in EPI-001 treated cells. This was supported by an increase in autophagosome punctuation observed by Autodot staining. CONCLUSIONS Our data demonstrate that the treatment with EPI-001 leads to increased autophagic activity in LNCaP prostate cancer cells. Combination of N-terminal androgen receptor blockage with simultaneous autophagy inhibition increases the antitumor effect of EPI-001 in vitro. This may offer a promising strategy to overcome resistance mechanisms in castration resistant prostate cancer. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e1108 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Benedikt Kranzbühler More articles by this author Souzan Salemi More articles by this author Tullio Sulser More articles by this author Daniel Eberli More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...