title: Claudin-4 activity in ovarian tumor cell apoptosis resistance and migration.
abstract: Claudin-4 is a transmembrane protein expressed at high levels in the majority of epithelial ovarian tumors, irrespective of subtype, and has been associated with tumor cells that are both chemoresistant and highly mobile. The objective of this study was to determine the functional role that claudin-4 plays in apoptosis resistance and migration as well as the therapeutic utility of targeting claudin-4 activity with a small mimic peptide.
  
  
  
  We examined claudin-4 activity in human ovarian tumor cell lines (SKOV3, OVCAR3, PEO4) using in vitro caspase and scratch assays as well as an in vivo mouse model of ovarian cancer. Claudin-4 activity was disrupted by treating cells with a small peptide that mimics the DFYNP sequence in the second extracellular loop of claudin-4. Claudin-4 expression was also altered using shRNA-mediated gene silencing.
  
  
  
  Both the disruption of claudin-4 activity and the loss of claudin-4 expression significantly increased tumor cell caspase-3 activation (4 to 10-fold, respectively) in response to the apoptotic inducer staurosporine and reduced tumor cell migration by 50 %. The mimic peptide had no effect on cells that lacked claudin-4 expression. Female athymic nude mice bearing ZsGreen-PEO4 ovarian tumors showed a significant decrease in ovarian tumor burden, due to increased apoptosis, after treatment with intraperitoneal injections of 4 mg/kg mimic peptide every 48 h for three weeks, compared to control peptide treated mice.
  
  
  
  Claudin-4 functionally contributes to both ovarian tumor cell apoptosis resistance and migration and targeting extracellular loop interactions of claudin-4 may have therapeutic implications for reducing ovarian tumor burden.
authors.affiliation: Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Denver, Anschutz Medical Campus, Mail Stop 8613, 12700 E. 19th Avenue, Aurora, Colorado, 80045, USA.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Hicks
authors.affiliation: Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Denver, Anschutz Medical Campus, Mail Stop 8613, 12700 E. 19th Avenue, Aurora, Colorado, 80045, USA.
authors.forename: Carly E
authors.initials: CE
authors.lastname: Galimanis
authors.affiliation: Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Denver, Anschutz Medical Campus, Mail Stop 8613, 12700 E. 19th Avenue, Aurora, Colorado, 80045, USA.
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Webb
authors.affiliation: Texas Oncology, Sammons Cancer Center, Baylor University Medical Center, 3410 Worth Street, Dallas, Texas, 75246, USA.
authors.forename: Monique A
authors.initials: MA
authors.lastname: Spillman
authors.affiliation: Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Denver, Anschutz Medical Campus, Mail Stop 8613, 12700 E. 19th Avenue, Aurora, Colorado, 80045, USA.
authors.forename: Kian
authors.initials: K
authors.lastname: Behbakht
authors.affiliation: Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Denver, Anschutz Medical Campus, Mail Stop 8613, 12700 E. 19th Avenue, Aurora, Colorado, 80045, USA.
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Neville
authors.affiliation: Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Denver, Anschutz Medical Campus, Mail Stop 8613, 12700 E. 19th Avenue, Aurora, Colorado, 80045, USA. Heidi.Wilson@ucdenver.edu.
authors.forename: Heidi K
authors.initials: HK
authors.lastname: Baumgartner
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics*; D002470:Cell Survival / Q000235:genetics; D062506:Claudin-4 / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D064593:Heterografts; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D047368:Tumor Burden
chemical_list: D062506:Claudin-4; D034741:RNA, Small Interfering; D053148:Caspase 3
keywords: Apoptosis; Claudin-4; Motility; Ovarian cancer