title: Dual inhibitor of phosphoinositide 3-kinase/mammalian target of rapamycin NVP-BEZ235 effectively inhibits cisplatin-resistant urothelial cancer cell growth through autophagic flux.
abstract: OBJECTIVE
  Therapeutically induced autophagic cell death has been proven to be effective in cases of solid tumors. The dual phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin (mTOR) inhibitor NVP-BEZ235 possesses antitumor activity against solid tumors. Inhibition of mTOR has been shown to elicit autophagy. In this study, we examined the antiproliferation and autophagic activities of NVP-BEZ235 in parental and cisplatin-resistant urothelial carcinoma (UC) cells.
  
  
  METHODS
  Two UC cell lines, NTUB1 and a cisplatin-resistant subline N/P(14), were applied to examine the cytotoxic effect of NVP-BEZ-235. The cell death mechanism was also evaluated.
  
  
  RESULTS
  NVP-BEZ235 was effective in inhibiting the growth of UC cells including parental and cisplatin-resistant cells on flow cytometry assay and Western blot. Although NVP-BEZ235 did not induce LC3-II conversion, it did elicit acidic vesicular organelle (AVO) development on flow cytometry. On Western blot, NVP-BEZ235 decreased p62 and phospho-Rb expressions in a concentration-dependent manner. GFP-LC3 conversion and the appearance of cleaved-GFP following NVP-BEZ235 treatment were demonstrated on Western blot. In addition, lysosomotropic inhibition of autophagy by chloroquine (CQ), an agent that is currently in clinical use and a known antagonist of autophagy, resulted in proliferation of UC cells. Thus, inhibition of autophagic flux by CQ appears to be a survival mechanism that counteracts the anticancer effects of NVP-BEZ235.
  
  
  CONCLUSIONS
  We demonstrated that NVP-BEZ235 inhibits UC cell proliferation by activating autophagic flux and cell cycle arrest, but does not induce apoptotic cell death. Our findings suggest that the anticancer efficacy of NVP-BEZ235 is due to autophagic flux and co-treatment with CQ counteracts the cytotoxic effect.
authors: Institute of Medicine, Chung Shan Medical University, Taiwan.
authors: Jian-ri
authors: JR
authors: Li
authors: Chen-Li
authors: CL
authors: Cheng
authors: Chi-Rei
authors: CR
authors: Yang
authors: Yen-Chuan
authors: YC
authors: Ou
authors: Ming-Ju
authors: MJ
authors: Wu
authors: Jiunn-Liang
authors: JL
authors: Ko
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D015153:Blotting, Western; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D005434:Flow Cytometry; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011804:Quinolines / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology
chemical_list: D002945:Cisplatin; D007093:Imidazoles; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011804:Quinolines; D058570:TOR Serine-Threonine Kinases; C546842:MTOR protein, human; C531198:dactolisib