Altered ß-catenin expression in oral mucosal dysplasia: a comparative study.

OBJECTIVE: The current study aimed to investigate the ß-catenin expression in oral leukoplakia (OL) with different degrees of epithelial dysplasia and normal oral mucosa. MATERIAL AND METHODS: Formalin-fixed, paraffin-embedded tissue samples of 39 OL (mild dysplasia n=19, moderate dysplasia n=13, and severe dysplasia n=7), and 10 normal oral mucosa (control group) were submitted to immunohistochemical reactions to anti-ß-catenin primary antibody. A qualitative ß-catenin analysis was performed based on the percentage of positive cells. The cellular location and the epithelial layer were also considered. The Chi-square test and the Fisher's exact test were used to verify possible differences in the ß-catenin expression among the OL groups. A p-value of <0.05 was considered statistically significant. RESULTS: Membranous expression of ß-catenin in parabasal and basal layers was gradually lost in the higher degrees of epithelial dysplasia. In normal oral mucosa, ß-catenin was detected only in the cytoplasmic membrane. However, a significant increase in cytoplasmic ß-catenin could be observed between mild and moderate dysplasia (Fisher Exact test - p<0.001) and between mild and severe dysplasia (p<0.001). CONCLUSIONS: The ß-catenin cytoplasmic expression observed in this study may represent the initial stage of modifications in the E-cadherin-catenin complex, along with morphological cellular changes.