title: Expression of claudin-5, claudin-7 and occludin in oral squamous cell carcinoma and their clinico-pathological significance.
abstract: BACKGROUND
  Claudin and occludin are the important tight junctions protein in human. The downregulation or upregulation of claudins and occludin might have a role in cancer development. The objective of this study was to investigate the expression of claudin-5, claudin-7 and occludin in oral squamous cell carcinoma (OSCC) and their relationships with the prognostically-related clinico-pathologic features.
  
  
  METHODS
  Standard indirect immunohistochemical technique using anti-claudin-5, anti-claudin-7 and anti-occludin was performed in formalin-fixed paraffin-embedded tissue sections of 66 OSCC samples from Faculty of Dentistry, Chulalongkorn University. The positive cases were divided into 2 groups, the low expression group (cases with less than 50% of positive cancer cells) and the high expression group for statistical analysis. Categorical analysis of the clinico-pathologic parameters together with univariate analysis using the Kaplan-Meier method and the log rank test were performed.
  
  
  RESULTS
  There were 22 male and 23 female patients enrolled in this study, with a mean age of 65.82+12.10 years. The claudin-5 immunoreactivity was observed in 26.6% of cases. The positive immunoreactivity of claudin-7 is more noted (93.3%). Only 4 cases showed occludin immunoreactivity (8.9%) and all of them show positivity less than 25% of cancer cells. Only loss of claudin-7 expression was associated with the high pathologic grade, advanced TNM staging, large tumor size, the presence of microscopic perineural, vascular invasions and regional lymph node involvement. There is a tendency towards the association of the higher claudin-7 expression and a longer survival time (P=0.012).
  
  
  CONCLUSIONS
  The results showed expression of claudin-5, claudin-7 and low expression of occludin in OSCC. Only claudin-7 expression showed impact on clinic-pathological parameter of OSCC.
  
  
  BACKGROUND
  Claudin, occludin, oral squamous cell carcinoma, tight junctions, oral cancer.
authors.affiliation: DDS, PhD, Assistant Professor. Department of Oral Pathology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Ekarat
authors.initials: E
authors.lastname: Phattarataratip
authors.affiliation: DDS, PhD, Assistant Professor. Faculty of Dental Medicine, Rangsit University, Thailand.
authors.forename: Kraisorn
authors.initials: K
authors.lastname: Sappayatosok