title: Small interfering RNA targeting heat shock protein 70 enhances chemosensitivity in human bladder cancer cells.
abstract: OBJECTIVE
  To evaluate the expression levels of heat shock protein 70 (HSP70) in human urothelial cancer of the bladder and to assess the therapeutic effects of treatment with small interfering RNA (siRNA) targeting HSP70 on human bladder cancer KoTCC-1 cells.
  
  
  METHODS
  HSP70 expression in bladder cancer specimens obtained from 235 patients were evaluated by immunohistochemical staining. We then analyzed changes in the growth and chemosensitivity of KoTCC-1 cells following treatment with HSP70 siRNA.
  
  
  RESULTS
  Expression levels of HSP70 protein in bladder cancer specimens were significantly related to major prognostic indicators, including pathologic stage and tumor grade. Treatment of KoTCC-1 with HSP70 siRNA resulted in a dose-dependent inhibition of HSP70 expression. HSP70 siRNA significantly inhibited the growth of KoTCC-1 compared with that after treatment with scrambled control siRNA. Among several chemotherapeutic agents, the most powerful synergistic cytotoxic effect was observed when KoTCC-1 was treated with gemcitabine plus HSP70 siRNA, which induced more than 50% reduction in the IC50 of gemcitabine. Furthermore, a significant increase in the subG0-G1 fraction of KoTCC-1 and the DNA fragmentation was observed only after combined treatment with HSP70 siRNA and sublethal doses of gemcitabine, but not after treatment with either agent alone. Similarly, caspase-3 and caspase-9, but not caspase-8, in KoTCC-1 were synergistically activated by combined treatment with gemcitabine and HSP70 siRNA.
  
  
  CONCLUSIONS
  Silencing of HSP70 expression using siRNA could be an attractive therapeutic strategy for bladder cancer by inducing inhibition of tumor growth as well as enhancing chemosensitivity.
authors: Division of Urology, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Hosny M
authors: HM
authors: Behnsawy
authors: Hideaki
authors: H
authors: Miyake
authors: Yuji
authors: Y
authors: Kusuda
authors: Masato
authors: M
authors: Fujisawa
mesh_terms: D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D045744:Cell Line, Tumor; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D034741:RNA, Small Interfering / Q000378:metabolism*; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism*; D019459:Urothelium / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D018840:HSP70 Heat-Shock Proteins; D034741:RNA, Small Interfering