title: Expression of p16 in oral cancer and premalignant lesions.
abstract: BACKGROUND
  Expression of p16 has been proposed as a marker for malignant transformation. This study aimed to evaluate p16 expression in oral squamous cell carcinoma (OSCC) and premalignant lesions including oral leukoplakia (OL) with and without dysplasia.
  
  
  METHODS
  Expression of p16 was investigated in 56 samples including OSCC, OL with and without dysplasia, and normal oral mucosa. Expression of p16 was identified by immunohistochemistry, using the CINtecTM p16INK4a Histology Kit. Both nuclear and/or cytoplasmic staining of the keratinocytes were considered to be positive and the percentage of positive cells was calculated.
  
  
  RESULTS
  Expression of p16 was detected in 3/16 (18.75%) cases of OSCC, in 4/15 (26.7%) cases of OL without dysplasia, and in none of OL with dysplasia and normal mucosa. No significant differences in p16 expression prevalence were found among OSCC, OL with and without dysplasia and normal mucosa. The percentages of positive cells in OSCC and OL without dysplasia were 0.89 and 0.17, respectively. No significant difference in the percentage of positive keratinocytes was found.
  
  
  CONCLUSIONS
  As a marker, p16 is not reliable for oral mucosal dysplasia and malignant transformation.
authors.affiliation: Department of Oral Medicine, Faculty of Dentistry, Mahidol University, Bangkok, Thailand. dtwbj@mahidol.ac.th
authors.forename: Waranun
authors.initials: W
authors.lastname: Buajeeb
authors.forename: Sopee
authors.initials: S
authors.lastname: Poomsawat
authors.forename: Jirapa
authors.initials: J
authors.lastname: Punyasingh
authors.forename: Sirima
authors.initials: S
authors.lastname: Sanguansin
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D002467:Cell Nucleus / Q000473:pathology; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000032:analysis*; D003593:Cytoplasm / Q000473:pathology; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D019942:Genes, p16; D006801:Humans; D015603:Keratinocytes / Q000473:pathology; D007972:Leukoplakia, Oral / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009061:Mouth Mucosa / Q000473:pathology; D009062:Mouth Neoplasms / Q000473:pathology*; D011230:Precancerous Conditions / Q000473:pathology*; D025803:Tumor Suppressor Protein p14ARF / Q000032:analysis*
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D025803:Tumor Suppressor Protein p14ARF