You have accessJournal of UrologyBladder Cancer: Basic Research & Pathophysiology II1 Apr 2016MP61-11 ENHANCED SENSITIVITY TO NVP-BEZ235 BY INHIBITION OF P62/SQSTM1 IN HUMAN BLADDER CANCER KOTCC-1 CELLS BOTH IN VITRO AND IN VIVO Bing Liu, Hideaki Miyake, and Masato Fujisawa Bing LiuBing Liu More articles by this author , Hideaki MiyakeHideaki Miyake More articles by this author , and Masato FujisawaMasato Fujisawa More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.885AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES To date, a number of studies have shown that activation of the cascade mediating mTOR signal transduction may play an important role in the progression of a wide variety of malignant tumors, including bladder cancer. However, several studies have shown the adaptive induction of autophagy by inhibitors of the PI3K/AKT/mTOR pathway, which promotes the survival of cancer cells, resulting in the potential limitation of their own efficacies. Therefore, we herein evaluated changes in the phenotypes of human bladder cancer KoTCC-1 cells both in vitro and in vivo after the RNA interference-mediated knockdown of the p62/SQSTM1 (p62), a multifunctional protein that has been implicated in selective autophagy, with a focus on the antitumor activity of NVP-BEZ235 (NVP), a recently developed dual PI3K/mTOR inhibitor. METHODS We established KoTCC-1 cells in which an expression vector containing short hairpin RNA (shRNA) targeting p62 was introduced (KoTCC-1/sh-p62). Antitumor activity of NVP in KoTCC-1/sh-p62 was compared with those in KoTCC-1 transfected with a control vector alone (KoTCC-1/C). RESULTS When cultured in standard medium, no significant difference was observed in growth patterns between KoTCC-1/sh-p62 and KoTCC-1/C; however, the sensitivity of KoTCC-1/sh-p62 to NVP was significantly higher than that of KoTCC-1/C, reducing the IC50 of NVP in KoTCC-1/sh-p62 by approximately 90% compared with that in KoTCC-1/C. A treatment with NVP strongly inactivated the PI3K/Akt/mTOR pathway in both cell lines. However, the treatment with NVP resulted in the activation of autophagy in KoTCC-1/C, but not in KoTCC-1/sh-p62, while the treatment of KoTCC-1/sh-p62 with NVP strongly induced apoptosis, which was accompanied by significantly lower amounts of c-IAP-1 and XIAP and larger amount of Bax than those in KoTCC-1/C. Despite the lack of a significant difference in the growth patterns of KoTCC-1/sh-p62 and KoTCC-1/C tumors without any treatment, the in vivo administration of NVP significantly inhibited the growth of KoTCC-1/sh-p62 tumors compared wioth that of KoTCC-1/C tumors, and the apoptotic index in KoTCC-1/sh-p62 tumors treated with NVP was significantly greater than that in KoTCC-1/C tumors. CONCLUSIONS These findings suggest that targeting p62 using shRNA interfering technology significantly enhanced the sensitivity of KoTCC-1 cells to NVP both in vitro and in vivo. Accordingly, the suppression of p62 in combination with NVP may be a promising therapeutic strategy for patients with muscle-invasive bladder cancer. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e807 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Bing Liu More articles by this author Hideaki Miyake More articles by this author Masato Fujisawa More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...