title: Selective up-regulation of claudin-1 and claudin-2 in colorectal cancer.
abstract: BACKGROUND
  To understand the molecular and morphological alterations in the tight junction in colorectal cancer (CRC) tissues, the expression of eight tight junction proteins in normal and cancer colorectal tissues were compared.
  
  
  METHODS
  Adenocarcinoma tissues and paired normal mucosa were resected from surgical specimens of CRC patients. The expression of occludin, ZO-1, ZO-2, and claudin-1 -5 was analyzed at the mRNA level by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by immunohistochemistry.
  
  
  RESULTS
  The expression of claudin-1 and claudin-2 in cancer tissues was upregulated 40- and 49.2-fold, respectively, at the mRNA level, as compared with that in normal tissues. The up-regulation of these two claudins was also observed at the protein level and it appeared to depend on the depth of tumor invasion.
  
  
  CONCLUSIONS
  Claudin-1 and claudin-2 were found to be overexpressed in CRC tissues. They may be useful as tumor markers and targets for the treatment of colorectal cancer.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Fukuoka University, Fukuoka, Japan. t-kinu@fukuoka-u.ac.jp
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Kinugasa
authors.forename: Qun
authors.initials: Q
authors.lastname: Huo
authors.forename: Daijiro
authors.initials: D
authors.lastname: Higashi
authors.forename: Hirotomo
authors.initials: H
authors.lastname: Shibaguchi
authors.forename: Motomu
authors.initials: M
authors.lastname: Kuroki
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Tanaka
authors.forename: Kitarou
authors.initials: K
authors.lastname: Futami
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Ken
authors.initials: K
authors.lastname: Hachimine
authors.forename: Shinichi
authors.initials: S
authors.lastname: Maekawa
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nabeshima
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwasaki
authors.forename: Masahide
authors.initials: M
authors.lastname: Kuroki
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D062445:Claudin-1; D057167:Claudins; D015179:Colorectal Neoplasms / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008875:Middle Aged; D062793:Occludin; D010750:Phosphoproteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019108:Tight Junctions / Q000378:metabolism*; D015854:Up-Regulation; D062826:Zonula Occludens-1 Protein
chemical_list: D014408:Biomarkers, Tumor; C568108:CLDN1 protein, human; C491875:CLDN2 protein, human; D062445:Claudin-1; D057167:Claudins; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; D012333:RNA, Messenger; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein