title: TSPAN8, identified by Escherichia coli ampicillin secretion trap, is associated with cell growth and invasion in gastric cancer.
abstract: BACKGROUND
  Gastric cancer (GC) is one of the most common human cancers. Genes expressed only in cancer tissue, especially on the cell membrane, will be useful biomarkers for cancer diagnosis and therapeutics.
  
  
  METHODS
  To identify novel genes encoding transmembrane protein specifically expressed in GC, we generated an Escherichia coli ampicillin secretion trap (CAST) library from diffuse-type GC cell line MKN-45. CAST is a survival-based signal sequence trap method that exploits the ability of mammalian signal sequences to confer ampicillin resistance to a mutant β-lactamase lacking the endogenous signal sequence.
  
  
  RESULTS
  By sequencing 1,536 colonies, we identified 23 genes encoding the transmembrane protein present in GC. Among these genes, TSPAN8 (also known as CO-029 and TM4SF3) gene, which encodes transmembrane protein tetraspanin 8, was emphasized as a candidate. Immunohistochemical analysis of tetraspanin 8 in human GC tissues revealed that 72 (34 %) of 210 GC cases were positive for tetraspanin 8, and microvessel density was significantly higher in tetraspanin 8-positive GC than in tetraspanin 8-negative GC. Furthermore, univariate and multivariate analyses revealed that tetraspanin 8 expression is an independent prognostic classifier of patients with GC. TSPAN8 knockdown by siRNA reduced the invasion of GC cell line. The reduction of invasiveness was retrieved by the tetraspanin 8-containing exosome.
  
  
  CONCLUSIONS
  These results suggest that tetraspanin 8 is involved in tumor progression and is an independent prognostic classifier in patients with GC.
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-Ku, Hiroshima, 734-0037, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Anami
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-Ku, Hiroshima, 734-0037, Japan.
authors.forename: Naohide
authors.initials: N
authors.lastname: Oue
authors.affiliation: Department of Gastrointestinal Surgery, Oita University Faculty of Medicine, 1-1 Hasamamachiidaigaoka, Yufu, 879-5503, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Noguchi
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-Ku, Hiroshima, 734-0037, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Sakamoto
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-Ku, Hiroshima, 734-0037, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sentani
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-Ku, Hiroshima, 734-0037, Japan.
authors.forename: Tetsutaro
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-Ku, Hiroshima, 734-0037, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Naito
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-Ku, Hiroshima, 734-0037, Japan.
authors.forename: Htoo Zarni
authors.initials: HZ
authors.lastname: Oo
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-Ku, Hiroshima, 734-0037, Japan. wyasui@hiroshima-u.ac.jp.
authors.forename: Wataru
authors.initials: W
authors.lastname: Yasui
mesh_terms: D000368:Aged; D000667:Ampicillin / Q000494:pharmacology; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004926:Escherichia coli / Q000235:genetics; D055354:Exosomes / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D015723:Gene Library; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D059470:Tetraspanins / Q000235:genetics* / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; C065609:TSPAN8 protein, human; D059470:Tetraspanins; D000667:Ampicillin
keywords: Gastric cancer; Neovascularization; Prognosis