Methods: cases of hyperplasia (n=15), mild dysplasia (n=12), moderate-to-severe dysplasia (n=11) and squamous cell carcinoma (n=22) were immunohistochemically stained with E-cadherin, beta-catenin and TGF-beta. Semiquantitative assessment of the membranous E-cadherin and beta-catenin and membranous and cytoplasmic TGF-beta stains was performed separately for the basal, middle and upper epithelial thirds. Results were expressed as the mean staining score per epithelial "third". In addition, the mean "total score", i.e., the sum of the points allocated to each third in each group, was computed. Differences in the mean staining scores were analyzed by ANOVA with repeated measures and correlations among mean "total scores" by Pearson.
Results: E-cadherin and beta-catenin in hyperplasia and dysplasia showed a similar pattern of significantly higher expression in the middle third compared to the basal and upper thirds (p<0.05). In carcinoma, E-cadherin level was significantly higher in the upper and basal thirds compared to the other groups (p<0.05). Within this group, a significant decrease in E-cadherin was observed from the upper to the basal third (p<0.001). TGF-beta showed an increase from the upper to the basal thirds in all study groups; expression in the carcinomas was significantly higher compared to all the other study groups in all "thirds" (p<0.001). Mean "total score" of E-cadherin correlated with that of beta-catenin and TGF-beta (p=0.009).
Conclusion: membranous expression of E-cadherin and beta -catenin in hyperplastic and dysplastic lesions is related to the epithelial strata. Overexpression of E-cadherin in carcinomas may be associated with the degree of differentiation and that of TGF-beta may reflect its tumor suppressor role.
Study was supported by the Vladimir Schreiber and Tivor Bilha funds, Sackler Faculty of Medicine, Tel Aviv University.