E-cadherin and β-catenin expression patterns in malignant melanoma assessed by image analysis

Background: We investigated the expression of E-cadherin and beta-catenin in melanoma. Both proteins are components of adherens junctions but also play signalling roles in the wnt signal transduction pathway. Materials and methods: Seventy malignant melanomas were analysed by immunohistochemistry and evaluated by image analysis as staining density, i.e. light permeability (LP). Results: Comparison of mean values of relative LP for E-cadherin and beta-catenin in tumor tissue shows that levels of E-cadherin protein are significantly lower (259.67-116.23; t = 22.7; p = 0.000). The comparison of mean values of the relative LP of E-cadherin in melanoma to the LP in the adjacent normal skin also shows that the expression of E-cadherin in tumor is significantly lower (256.06-169.87; t = 11.55, p = 0.000). beta-catenin was observed in the cytoplasm in 30.6% of patients, in 24.2% in the cell membrane, in 21% in both the cytoplasm and membrane, in 1.6% in the membrane and nucleus and in 4.8% in the cytoplasm and nucleus, whereas in 17.7% of patients beta-catenin could not be observed. Patients with Clark 4 and 5 had significantly less beta-catenin than patients with Clark 2 and 3 (chi(2) = 12.854; p = 0.005). Conclusions: Changes in E-cadherin and beta-catenin levels have important roles in melanoma and could be used as molecular markers of disease progression.