title: Analysis of the distribution and expression of claudin-1 tight junction protein in the oral cavity.
abstract: BACKGROUND
  Claudins are the main sealing proteins of the intercellular tight junctions and play an important role in cancer cell progression and dissemination. The authors have previously shown that overexpression of claudin-1 is associated with angiolymphatic and perineural invasion, consistent with aggressive tumor behavior and with advanced stage disease in oral squamous cell carcinomas (OSCCs). Our goal in this study was to examine claudin-1 expression in a tissue microarray of OSCCs taken from multiple sites within the oral cavity.
  
  
  METHODS
  This study examined and compared the expression of claudin-1 by immunohistochemistry in 60 tissue samples (49 OSCCs and 10 cases of non-neoplastic tissue, single core per case) were analyzed for claudin-1 expression by immunohistochemistry. The tumors included SCCs from the tongue (n=28), the cheek (n=9), gingival (n=4), lip (n=3), and oral cavity (n=5). Nonmalignant normal oral mucosa from the tongue (unmatched cases, n=2). Cancer adjacent tissue samples were taken from the tongue (n=6), gingival (n=2), and palate (n=1).
  
  
  RESULTS
  This study demonstrates the expression of claudin-1 protein across a sample of OSCCs originating from multiple locations in the oral cavity. The highest expression of claudin-1 was observed in well-differentiated OSCCs, whereas poorly differentiated OSCCs exhibited mostly negative staining for claudin-1. In addition, we hereby report differential pattern of expression among tumors of different sites within the oral cavity, and between benign and cancerous samples. Our understanding of the exact function and role of claudin-1 in tumorigenesis is expanding exponentially.
authors.affiliation: *Department of Pathology, College of Medicine, Alfaisal University †Department of Pathology, King Fahd Medical City, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Abderrahman
authors.initials: A
authors.lastname: Ouban
authors.forename: Atif
authors.initials: A
authors.lastname: Ahmed
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D016022:Case-Control Studies; D062445:Claudin-1 / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009055:Mouth / Q000378:metabolism* / Q000473:pathology; D009062:Mouth Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D019108:Tight Junctions / Q000378:metabolism* / Q000473:pathology; D046888:Tissue Array Analysis
chemical_list: C568108:CLDN1 protein, human; D062445:Claudin-1