title: Expression of claudin-7 and loss of claudin-18 correlate with poor prognosis in gastric cancer.
abstract: BACKGROUND
  The purpose of this study was to evaluate the expression of claudin-3, claudin-7, and claudin-18 in gastric cancer and to determine the significance of these proteins for patient outcome.
  
  
  METHODS
  A total of 134 samples were obtained from surgically resected specimens from patients who were diagnosed with gastric carcinoma at a single institution. Paraffin tissue sections from tissue microarray blocks were examined with immunohistochemistry for the expression of claudin-3, claudin-7, and claudin-18.
  
  
  RESULTS
  In normal gastric tissues, positive immunoreactivity was detected for claudin-18 but not for claudin-3 or claudin-7. Claudin-3 and claudin-7 were expressed in 25.4% and 29.9% of the gastric cancer tissues, respectively. However, 51.5% of gastric cancer tissues exhibited reduced expression of claudin-18. Claudin-7 expression was significantly lower in cases with diffuse histologic type and positive lymphatic invasion. There was a significant inverse correlation between claudin-18 expression and perineural invasion. In the survival analysis, the overall survival time was shorter in patients with claudin-7 expression than in those without claudin-7 expression. However, the overall survival was longer in patients with claudin-18 expression than in those without claudin-18 expression.
  
  
  CONCLUSIONS
  Our data suggest that the up-regulation of claudin-3 and claudin-7 and the down-regulation of claudin-18 may play a role in the carcinogenesis of gastric cancer. Furthermore, the expression of claudin-7 and the loss of claudin-18 may be independent indicators of a poor prognosis in patients with gastric cancer.
authors: Department of Surgery, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea.
authors: Kyong-Hwa
authors: KH
authors: Jun
authors: Department of Surgery, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea.
authors: Ji-Hyun
authors: JH
authors: Kim
authors: Department of Hospital Pathology, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea. Electronic address: apjjh225@catholic.ac.kr.
authors: Ji-Han
authors: JH
authors: Jung
authors: Department of Hospital Pathology, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea.
authors: Hyun-Joo
authors: HJ
authors: Choi
authors: Department of Surgery, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea. Electronic address: hchin@catholic.ac.kr.
authors: Hyung-Min
authors: HM
authors: Chin
mesh_terms: D000368:Aged; D057167:Claudins / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D013274:Stomach Neoplasms / Q000378:metabolism*; D046888:Tissue Array Analysis
chemical_list: C486683:CLDN18 protein, human; C473255:CLDN7 protein, human; D057167:Claudins
keywords: Claudin-18; Claudin-3; Claudin-7; Gastric cancer