title: Claudins 1, 4, 5, 7 and occludin in ameloblastomas and developing human teeth.
abstract: BACKGROUND
  To analyze the distribution pattern of claudins 1, 4, 5, 7 and occludin in benign and malignant ameloblastomas and developing human teeth.
  
  
  METHODS
  Paraffin-embedded tissue specimens of 25 benign and four malignant ameloblastomas and two developing human teeth were examined immunohistochemically using antibodies against claudins 1, 4, 5, 7 and occludin.
  
  
  RESULTS
  In ameloblastomas strongest expression was seen for claudins 1 and 7 while claudin 4 was expressed less frequently. Claudin 5 and occludin were seen only in a minority of cases. There were no evident differences in the expression of claudins or occludin neither between different histologic subtypes of ameloblastomas nor between benign or malignant cases. The strongest expression for claudins was present in the central stellatum reticulum-like cells surrounding the microcysts and in the areas with squamous differentiation of the ameloblastomas. In developing teeth both claudin 1 and 7 stained strongly in the enamel epithelium, ameloblasts, and enamel matrix, but staining for claudin 4 was relatively weak. Claudin 5 was preferentially expressed only in vessels, and occludin staining ranged from negative to weak in ameloblastomas and teeth germs.
  
  
  CONCLUSIONS
  There were no clear differences in the expression levels between benign and malignant ameloblastic tumors. The overexpression of claudins in the areas with microcyst formation may indicate their attempt to maintain the interepithelial cohesion of the cells. The strong immunoreactivity of ameloblasts and newly synthesized enamel matrix for claudins 1 and 7 indicates that they may be involved in cell signaling influencing enamel formation.
authors.affiliation: Department of Diagnostics and Oral Medicine, Institute of Dentistry, University of Oulu, Oulu, Finland.
authors.forename: Ibrahim O
authors.initials: IO
authors.lastname: Bello
authors.forename: Ylermi
authors.initials: Y
authors.lastname: Soini
authors.forename: Pieter J
authors.initials: PJ
authors.lastname: Slootweg
authors.forename: Tuula
authors.initials: T
authors.lastname: Salo
mesh_terms: D000564:Ameloblastoma / Q000473:pathology*; D000565:Ameloblasts / Q000473:pathology; D000566:Amelogenesis / Q000502:physiology; D002454:Cell Differentiation; D062445:Claudin-1; D062506:Claudin-4; D062507:Claudin-5; D057167:Claudins; D003743:Dental Enamel / Q000473:pathology; D004658:Enamel Organ / Q000473:pathology; D004848:Epithelium / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000032:analysis*; D062793:Occludin; D009805:Odontogenesis / Q000502:physiology*; D016612:Paraffin Embedding; D019108:Tight Junctions / Q000473:pathology*; D014083:Tooth Germ / Q000473:pathology*
chemical_list: C568108:CLDN1 protein, human; C568157:CLDN4 protein, human; C107466:CLDN5 protein, human; C473255:CLDN7 protein, human; D062445:Claudin-1; D062506:Claudin-4; D062507:Claudin-5; D057167:Claudins; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin