title: Claudin-4-targeted therapy using Clostridium perfringens enterotoxin for prostate cancer.
abstract: BACKGROUND
  Clostridium perfringens enterotoxin (CPE) triggers lysis of epithelial cells through binding to tight-junction proteins claudin-3 (Cldn3) and Cldn4, which are over-expressed in prostate cancer. We investigated the potential of Cldn-targeted therapy using CPE.
  
  
  METHODS
  We investigated the expression levels and subcellular localization of Cldn3 and Cldn4 in primary human prostate cancer tissues, human prostate cancer cell lines (22Rv1, DU145, and PC3) and normal human prostate epithelial cells (PrECs). Cytotoxic effects of CPE on these cells were examined by colorimetric assay. We studied whether knockdown of Cldn3 and/or Cldn4 expression using RNA interference influenced CPE-mediated cytotoxicity. The therapeutic effect of CPE was evaluated in PC3 xenografts in athymic mice.
  
  
  RESULTS
  Cldn4 and Cldn3 were expressed in primary human prostate cancer tissues, 22Rv1, DU145, and PC3. Cldn4 protein was expressed in PrEC. Cldn4 was distributed along whole cell membranes of the cancer cell lines, whereas it was localized at tight junctions in PrEC. CPE-mediated cytotoxicity was greatly detected in PC3, but was hardly detectable in PrEC. Reduced expression of Cldn4, but not Cldn3, led to remarkable decreases of cytotoxicity in both PC3 and 22Rv1. The injection of CPE around PC3 xenografts significantly suppressed tumor growth.
  
  
  CONCLUSIONS
  CPE-mediated cytotoxicity was observed in human prostate cancer cell lines, but barely detected in normal human PrECs. The cytotoxic effect depended not only on the expression level of Cldn4 protein but also on its subcellular localization. These results suggest that Cldn4-targeted therapy using CPE may be a new treatment for prostate cancer.
authors.affiliation: Department of Pathology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Maeda
authors.forename: Masaki
authors.initials: M
authors.lastname: Murata
authors.forename: Hideki
authors.initials: H
authors.lastname: Chiba
authors.forename: Akira
authors.initials: A
authors.lastname: Takasawa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tanaka
authors.forename: Takashi
authors.initials: T
authors.lastname: Kojima
authors.forename: Naoya
authors.initials: N
authors.lastname: Masumori
authors.forename: Taiji
authors.initials: T
authors.lastname: Tsukamoto
authors.forename: Norimasa
authors.initials: N
authors.lastname: Sawada
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D062465:Claudin-3; D062506:Claudin-4; D057167:Claudins / Q000187:drug effects* / Q000378:metabolism*; D004768:Enterotoxins / Q000494:pharmacology* / Q000627:therapeutic use*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008819:Mice, Nude; D011467:Prostate / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D034622:RNA Interference; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism; D016896:Treatment Outcome; D023041:Xenograft Model Antitumor Assays
chemical_list: C568122:CLDN3 protein, human; C568157:CLDN4 protein, human; D062465:Claudin-3; D062506:Claudin-4; D057167:Claudins; C568123:Cldn3 protein, mouse; C568158:Cldn4 protein, mouse; D004768:Enterotoxins; C035598:enterotoxin, Clostridium