title: Claudin 4 Is differentially expressed between ovarian cancer subtypes and plays a role in spheroid formation.
abstract: Claudin 4 is a cellular adhesion molecule that is frequently overexpressed in ovarian cancer and other epithelial cancers. In this study, we sought to determine whether the expression of claudin 4 is associated with outcome in ovarian cancer patients and may be involved in tumor progression. We examined claudin 4 expression in ovarian cancer tissues and cell lines, as well as by immunohistochemical staining of tissue microarrays (TMAs; n = 500), spheroids present in patients' ascites, and spheroids formed in vitro. Claudin 4 was expressed in nearly 70% of the ovarian cancer tissues examined and was differentially expressed across ovarian cancer subtypes, with the lowest expression in clear cell subtype. No association was found between claudin 4 expression and disease-specific survival in any subtype. Claudin 4 expression was also observed in multicellular spheroids obtained from patients' ascites. Using an in vitro spheroid formation assay, we found that NIH:OVCAR5 cells treated with shRNA against claudin 4 required a longer time to form compact spheroids compared to control NIH:OVCAR5 cells that expressed high levels of claudin 4. The inability of the NIH:OVCAR5 cells treated with claudin 4 shRNA to form compact spheroids was verified by FITC-dextran exclusion. These results demonstrate a role for claudin 4 and tight junctions in spheroid formation and integrity.
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA; E-Mails: boyla002@umn.edu (K.L.M.B.); benjamin.misemer@gmail.com (B.M.); deryc004@umn.edu (M.S.D.); ande0555@umn.edu (J.D.A.); harr0750@umn.edu (K.M.H.); pambu001@umn.edu (S.E.P.).
authors.forename: Kristin L M
authors.initials: KL
authors.lastname: Boylan
authors.forename: Benjamin
authors.initials: B
authors.lastname: Misemer
authors.forename: Melissa S
authors.initials: MS
authors.lastname: De Rycke
authors.forename: John D
authors.initials: JD
authors.lastname: Andersen
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Harrington
authors.forename: Steve E
authors.initials: SE
authors.lastname: Kalloger
authors.forename: C Blake
authors.initials: CB
authors.lastname: Gilks
authors.forename: Stefan E
authors.initials: SE
authors.lastname: Pambuccian
authors.forename: Amy P N
authors.initials: AP
authors.lastname: Skubitz
mesh_terms: D001201:Ascites / Q000378:metabolism / Q000473:pathology; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D002277:Carcinoma / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D062506:Claudin-4 / Q000235:genetics / Q000378:metabolism*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D018874:Spheroids, Cellular / Q000378:metabolism* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D062506:Claudin-4