title: Down-regulation of CD9 in human ovarian carcinoma cell might contribute to peritoneal dissemination: morphologic alteration and reduced expression of beta1 integrin subsets.
abstract: Peritoneal dissemination is one of the main causes of death in cancer patients. Pathophysiology of metastasis has been well investigated, but the mechanism of diffuse spread of tumor colonies in the peritoneal cavity is not fully understood. CD9 is a member of tetraspanin and its down-regulation is known to be involved in poor prognosis. To investigate the significance of the down-regulation of CD9, HTOA, an ovarian carcinoma cell line that highly expressed CD9, was transiently transfected with small interfering RNA (siRNA) against CD9, and CD9-negative cells (HTOA(CD9-)) were purified. HTOA(CD9-) showed altered adhesion patterns on Matrigel, collagen, fibronectin, and laminin compared with those of control siRNA-transfected HTOA (control-HTOA). Flow cytometry and fluorescence cytostainings revealed that the expression levels of integrins beta1, alpha2, alpha3beta1, alpha5, and alpha6 were lower in HTOA(CD9-) than those of control-HTOA. HTOA(CD9-) showed altered expression of junctional and cytoskeletal molecules. By time-lapse video microscopy, control-HTOA showed solid adhesion to extracellular matrix and formed cobblestone pattern, whereas HTOA(CD9-) showed weaker adhesion and were distributed as diffuse spots. To examine whether the expression level of CD9 change during tumor dissemination, HTOA-P, a highly disseminative subclone of HTOA, was established. HTOA-P showed distinctive down-regulation of CD9 at mRNA and protein levels, and showed similar morphologic alteration as HTOA(CD9-) did. These findings indicate that the down-regulation of CD9 may be an acquired event in the process of tumor dissemination. Down-regulated CD9 may attenuate the expression of several integrins and rearrange junctional and cytoskeletal molecules that might contribute to dissemination of ovarian carcinomas.
authors.affiliation: Department of Molecular Pathology, Chiba University Graduate School of Medicine, Chiba, Japan. furuya@faculty.chiba-u.ac.jp
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Furuya
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kato
authors.forename: Norihiro
authors.initials: N
authors.lastname: Nishimura
authors.forename: Isamu
authors.initials: I
authors.lastname: Ishiwata
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ikeda
authors.forename: Ryoko
authors.initials: R
authors.lastname: Ito
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshiki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishikura
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics; D045744:Cell Line, Tumor; D003094:Collagen; D003599:Cytoskeleton / Q000378:metabolism; D015536:Down-Regulation; D004338:Drug Combinations; D005260:Female; D005353:Fibronectins; D006801:Humans; D019012:Integrin beta1 / Q000096:biosynthesis*; D007797:Laminin; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010051:Ovarian Neoplasms / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D010534:Peritoneal Neoplasms / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000556:secondary*; D011509:Proteoglycans; D034741:RNA, Small Interfering / Q000737:chemistry / Q000235:genetics; D060245:Tetraspanin 29; D019108:Tight Junctions / Q000378:metabolism; D014162:Transfection
chemical_list: D015703:Antigens, CD; C554869:CD9 protein, human; C554870:Cd9 protein, mouse; D004338:Drug Combinations; D005353:Fibronectins; D019012:Integrin beta1; D007797:Laminin; D008562:Membrane Glycoproteins; D011509:Proteoglycans; D034741:RNA, Small Interfering; D060245:Tetraspanin 29; C059485:matrigel; D003094:Collagen