title: Enhanced sensitivity to mitomycin C by abating heat shock protein 70 expression in human bladder cancer cell line of BIU-87.
abstract: BACKGROUND
  Bladder cancer is a relatively common tumor in the urinary system, in which mitomycin C (MMC)-based chemotherapy or combination chemotherapy has been mainly used to treat patients with advanced bladder cancer. The prognosis of patients with advanced bladder cancer is still extremely poor in spite of recent therapeutic advances. To improve the prognosis, the sensitivity of tumor cells to mitomycin C by the induction of apoptosis with the abating heat shock protein 70 (HSP70) expression in human bladder cancer cell lines of BIU-87 was investigated.
  
  
  METHODS
  HSP70 expression was abated in BIU-87 cells by HSP mRNA antisense oligomers. MTT assay and the clone-forming test were used for evaluating the sensitivity of cells to MMC. Apoptosis was assessed using both fluorescent microscopy after staining the cells with Hoechst 33258 and DNA fragment ladder agarose electrophoresis. Thirty-two male six-week-old BALB/c nude mice, at the beginning of the experiment, were used to evaluate the effect of antisense oligomers (ASO) on the tumor formation in vivo.
  
  
  RESULTS
  HSP70 expression in BIU-87 was effectively abated by HSP70 mRNA antisense oligomers. The percentage of apoptotic cells in ASO group was greater than in sense oligomers (SO) [P < 0.05, (18.31 +/- 2.89)% vs (1.89 +/- 0.74)%], nonsense oligomers (NO) [P < 0.05, (18.31 +/- 2.89)% vs (1.78 +/- 0.92)%] and blank groups [P < 0.05, (18.31 +/- 2.89)% vs (1.87 +/- 0.84)%], while the sensitivity of tumor cells to mitomycin C was enhanced. The in vivo tumor inhibition rate of ASO plus MMC (> 50%) was more than that of ASO or MMC group alone (all P < 0.05).
  
  
  CONCLUSIONS
  The abating level of HSP70 expression can strengthen the sensitivity of BIU-87 to MMC. One of this effect might be related to the induction of apoptosis by abating HSP70 expression.
authors.affiliation: Department of Urology, Peking University People's Hospital, Beijing 100044, China. hlf379@sohu.com
authors.forename: Ling-feng
authors.initials: LF
authors.lastname: He
authors.forename: Kao-peng
authors.initials: KP
authors.lastname: Guan
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yan
authors.forename: Hai-yun
authors.initials: HY
authors.lastname: Ye
authors.forename: Ke-xin
authors.initials: KX
authors.lastname: Xu
authors.forename: Liang
authors.initials: L
authors.lastname: Ren
authors.forename: Shu-kun
authors.initials: SK
authors.lastname: Hou
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D006801:Humans; D016685:Mitomycin / Q000494:pharmacology*; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology
chemical_list: D018840:HSP70 Heat-Shock Proteins; D020319:Oligodeoxyribonucleotides, Antisense; D012333:RNA, Messenger; D016685:Mitomycin