title: Expression of p63 and p16 in primary and recurrent pterygia.
abstract: BACKGROUND
  p63 and p16 have been described as stem-cell markers of squamous epithelium. In an attempt to obtain new insights into the pathogenesis of pterygium, this study aims to evaluate the relationship between p63 and p16 expression in primary and recurrent pterygia.
  
  
  METHODS
  Samples of primary (n=56) and recurrent (n=14) pterygia and normal bulbar conjunctival tissue (n=11) were submitted to immunohistochemical study to evaluate the expression of p63 and p16 in these tissues.
  
  
  RESULTS
  Most of the cells stained for p63 were located in the basal layer of the normal conjunctiva, in the lower two-thirds of the epithelium of primary pterygia, and throughout all epithelial layers of recurrent pterygia. In normal conjunctivae, p16 expression was rarely expressed. Primary and recurrent pterygium groups exhibited increased p16 expression, with cytoplasmic staining in the primary group, and cytoplasmic or nuclear staining in the recurrent group.
  
  
  CONCLUSIONS
  The overexpression of p63 and p16 observed in the present study reinforces likelihood of involvement of these genes in the pathogenesis of pterygium, perhaps related to the intense cellular turnover with substitution of superficial epithelial cells by less differentiated forms. This loss of normal cellular differentiation of the epithelial layers could explain the high rates of recurrence overall in the recurrent pterygia.
authors.affiliation: Department of Surgery and Anatomy, Faculty of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil. framalho@fmrp.usp.br
authors.forename: Fernando S
authors.initials: FS
authors.lastname: Ramalho
authors.forename: Claudia
authors.initials: C
authors.lastname: Maestri
authors.forename: Leandra N Z
authors.initials: LN
authors.lastname: Ramalho
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ribeiro-Silva
authors.forename: Erasmo
authors.initials: E
authors.lastname: Romão
mesh_terms: D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008875:Middle Aged; D011625:Pterygium / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D012008:Recurrence
chemical_list: C081876:CKAP4 protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D008565:Membrane Proteins