title: Expression of the cell cycle regulation proteins p53 and p21WAF1 in different types of non-dysplastic leukoplakias.
abstract: OBJECTIVE
  The aim of this study was to analyze the immunolabeling of two cell cycle protein regulators, p53 and p21WAF1, in non-dysplastic leukoplakias with different epithelial alterations: acanthosis, hyperkeratosis and acanthosis combined with hyperkeratosis, and compare them with dysplastic leukoplakias.
  
  
  METHODS
  This was a prospective cohort study involving 36 patients with oral homogeneous leukoplakias. excisional biopsies were performed and the patients remain under clinical follow-up. The leukoplakias were divided into four groups: 6 acanthosis, 9 hyperkeratosis, 10 acanthosis combined with hyperkeratosis, and 11 epithelial dysplasias. Paraffin-embebeded sections were immunostained for p53 and p21WAF1. Five hundred cells from the basal layer and 500 from the parabasal layer were counted to determine the percentage of positive cells. A qualitative analysis was also carried out to determine the presence or absence of immunohistochemical staining in the intermediate and superficial layers. Groups were compared with ANOVA (p<0.05). Pearson's correlation coefficient was used to test for associations between the two markers, p53 and p21WAF1.
  
  
  RESULTS
  No leukoplakia recurred and no malignant transformation was observed whitin a follow-up period of 3-6 years. The mean percentage of p53 staining in the basal and parabasal layers was similar in all groups. p21WAF1 staining differed between layers was as follows: in the basal, only 3 to 4% of cells were stained, while in the parabasal, between 16 and 28% of the epithelial cells were stained in the four different studied groups with no statistically significant difference (p>0.05).
  
  
  CONCLUSIONS
  Our findings failed to differentiate the non-dysplastic lesions by means of p53 and p21WAF1 immunostaining, notwithstanding similar profiles between non-dysplastic and dysplastic leukoplakias were observed.
authors.affiliation: Oral Pathology, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Visioli
authors.forename: Isabel Silva
authors.initials: IS
authors.lastname: Lauxen
authors.forename: Manoel
authors.initials: M
authors.lastname: Sant'ana Filho
authors.forename: Pantelis Varvaki
authors.initials: PV
authors.lastname: Rados
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000032:analysis*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000032:analysis* / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007972:Leukoplakia, Oral / Q000737:chemistry* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D016612:Paraffin Embedding; D011446:Prospective Studies; D016159:Tumor Suppressor Protein p53 / Q000032:analysis* / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016159:Tumor Suppressor Protein p53