title: Increased cyclooxygenase-2 expression in large flat colorectal tumors (laterally spreading tumors).
abstract: BACKGROUND
  Little is known about the molecular biological features of large flat tumors or laterally spreading tumors (LSTs) of the colon and rectum.
  
  
  METHODS
  The cyclooxygenase (COX)-2 protein expression level of LSTs was assessed immunohistochemically and compared with that of exophytic colorectal tumors. COX-2 expression in the dysplastic epithelial cells and the interstitial cells was evaluated independently.
  
  
  RESULTS
  Sixty-five LSTs and 65 exophytic tumors were randomly selected from the archives, and 61 and 59, respectively, were successfully analyzed. LSTs showed significantly more intense COX-2 protein expression in the dysplastic epithelial cells than the exophytic tumors ( P > 0.0001). COX-2-positive interstitial cells were also observed more frequently in LSTs than in the exophytic tumors ( P = 0.015).
  
  
  CONCLUSIONS
  Overexpression of COX-2 protein may play a crucial role in the tumorigenesis of colorectal LSTs. Chemoprevention, using nonsteroidal anti-inflammatory drugs (NSAIDs) or selective COX-2 inhibitors may be effective for treating this unique neoplasm, which sometimes defies endoscopic treatment.
authors.affiliation: First Department of Internal Medicine, Sapporo Medical University, Sapporo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamashita
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Arimura
authors.forename: Haruo
authors.initials: H
authors.lastname: Shimizu
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Takao
authors.initials: T
authors.lastname: Endo
authors.forename: Kohzoh
authors.initials: K
authors.lastname: Imai
authors.forename: Hiroo
authors.initials: H
authors.lastname: Yamano
mesh_terms: D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000473:pathology; D051546:Cyclooxygenase 2; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis*
chemical_list: D007527:Isoenzymes; D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases