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

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.

Seventy malignant melanomas were analysed by immunohistochemistry and evaluated by image analysis as staining density, i.e. light permeability (LP).

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 (chi2=12.854; p=0.005).

Changes in E-cadherin and beta-catenin levels have important roles in melanoma and could be used as molecular markers of disease progression.