title: Chemosensitization of gemcitabine-resistant human bladder cancer cell line both in vitro and in vivo using antisense oligonucleotide targeting the anti-apoptotic gene, clusterin.
abstract: OBJECTIVE
  To characterize changes in clusterin (sCLU-2) expression in bladder cancer cells after continuous treatment with gemcitabine and to determine whether knockdown of sCLU-2 can re-introduce sensitivity of gemcitabine-resistant cells to treatment with gemcitabine.
  
  
  METHODS
  A human bladder cancer cell line, UM-UC-3, was continuously exposed to increasing doses of gemcitabine in vitro, and a gemcitabine-resistant cell line UM-UC-3R was developed. The role of sCLU-2 in chemoresistant phenotype acquired in both in vitro and in vivo was then analysed using antisense oligonucleotide targeting the sCLU-2 gene (OGX-011).
  
  
  RESULTS
  Treatment of parental UM-UC-3 cells (UM-UC-3P) with gemcitabine induced transient up-regulation of sCLU-2 protein. There was a sustained increase in sCLU-2 expression levels in UM-UC-3R compared with UM-UC-3P cells (6.4-fold). Treatment of UM-UC-3R cells with OGX-011 resulted in a dose-dependent and sequence- specific inhibition in sCLU-2 expression. Furthermore, OGX-011 chemo-sensitized UM-UC-3R cells to gemcitabine in vitro with a reduction in the concentration that reduces the effect by 50% (IC50) from 100 nm to 10 nm. Tumour volume and the incidence of metastasis in nude mice injected with UM-UC-3R cells was significantly greater than those of nude mice injected with UM-UC-3P cells; however, systemic administration of OGX-011 plus a low dose of gemcitabine significantly suppressed tumour volume and the incidence of metastasis in both groups.
  
  
  CONCLUSIONS
  These findings suggest that sCLU-2 plays a significant role in the acquisition of chemoresistant phenotype in bladder cancer cells and the knockdown of sCLU-2 using OGX-011 combined with a chemotherapeutic agent could be an attractive approach for advanced bladder cancer through the enhancement of chemosensitivity.
authors.affiliation: The Prostate Centre, Vancouver General Hospital, Vancouver, British Columbia, Canada.
authors.forename: Mototsugu
authors.initials: M
authors.lastname: Muramaki
authors.forename: Alan
authors.initials: A
authors.lastname: So
authors.forename: Norihiro
authors.initials: N
authors.lastname: Hayashi
authors.forename: Richard
authors.initials: R
authors.lastname: Sowery
authors.forename: Hideaki
authors.initials: H
authors.lastname: Miyake
authors.forename: Masato
authors.initials: M
authors.lastname: Fujisawa
authors.forename: Martin E
authors.initials: ME
authors.lastname: Gleave
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D051152:Clusterin / Q000235:genetics / Q000378:metabolism*; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008819:Mice, Nude; D009362:Neoplasm Metastasis; D016376:Oligonucleotides, Antisense; D013873:Thionucleotides / Q000008:administration & dosage; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000235:genetics; D000093542:Gemcitabine
chemical_list: D051152:Clusterin; C503781:OGX-011; D016376:Oligonucleotides, Antisense; D013873:Thionucleotides; D003841:Deoxycytidine; D000093542:Gemcitabine