title: Enhanced radiation sensitivity in prostate cancer by inhibition of the cell survival protein clusterin.
abstract: OBJECTIVE
  The purpose of this study is to evaluate the role of the cell survival gene clusterin in radiation-induced cell death in human LNCaP and PC-3 prostate cancer models.
  
  
  METHODS
  Radiation sensitivities were compared in parental and clusterin-overexpressing LNCaP cells and in PC-3 cells and tumors treated with antisense or mismatch clusterin oligonucleotides.
  
  
  RESULTS
  Clusterin-overexpressing LNCaP cells were less sensitive to irradiation with significantly lower cell death rates (23% after 8 Gy) compared with parental LNCaP cells (50% after 8 Gy) 3 days after irradiation. Clusterin expression in PC-3 cells after radiation was found to be up-regulated in a dose-dependent manner in vitro by 70% up to 12 Gy and in vivo by 84% up to 30 Gy. Inhibition of clusterin expression in PC-3 cells using antisense oligonucleotides (ASOs) occurred in a sequence- and dose-dependent manner and significantly enhanced radiation-induced apoptosis and decreased PC-3 cell growth rate and plating efficiency. Compared with mismatch control oligonucleotide treatment, clusterin ASO treatment enhanced radiation therapy and significantly reduced PC-3 tumor volume in vivo by 50% at 9 weeks. In addition, TUNEL staining revealed increased number of apoptotic cells in clusterin ASO-treated and irradiated PC-3 tumors, compared with treatment with mismatch control oligonucleotides plus radiation.
  
  
  CONCLUSIONS
  These findings support the hypothesis that clusterin acts as a cell survival protein that mediates radioresistance through the inhibition of apoptosis. In vivo results further suggest that inactivation of clusterin using ASO technology might offer a novel strategy to improve results of radiation therapy for prostate cancer patients.
authors.affiliation: The Prostate Centre, Vancouver General Hospital, Vancouver, British Columbia V6H 3Z6, Canada.
authors.forename: Tobias
authors.initials: T
authors.lastname: Zellweger
authors.forename: Kim
authors.initials: K
authors.lastname: Chi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Miyake
authors.forename: Hans
authors.initials: H
authors.lastname: Adomat
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kiyama
authors.forename: Kirsten
authors.initials: K
authors.lastname: Skov
authors.forename: Martin E
authors.initials: ME
authors.lastname: Gleave
mesh_terms: D000818:Animals; D017209:Apoptosis; D015152:Blotting, Northern; D002455:Cell Division; D051152:Clusterin; D003114:Colony-Forming Units Assay; D017931:DNA Primers / Q000737:chemistry; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008819:Mice, Nude; D018832:Molecular Chaperones / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000532:radiotherapy*; D012333:RNA, Messenger / Q000378:metabolism; D011836:Radiation Tolerance; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured / Q000528:radiation effects
chemical_list: C495242:CLU protein, human; C495243:Clu protein, mouse; D051152:Clusterin; D017931:DNA Primers; D006023:Glycoproteins; D018832:Molecular Chaperones; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger