Markers of melanocytic tumour progression.

Melanoma progression markers can be defined as molecules with a preferential expression in one or a few stages of melanocytic tumour development. These molecules include growth factors, growth factors receptors, adhesion molecules, proteases and related components. Immunohistochemical studies suggest that some of these molecules are useful as prognostic markers in melanoma patients. In cutaneous melanocytic lesions, the distribution of E-cadherin, a member of a family of cell adhesion molecules that mediate cell-cell interactions by means of Ca2+ dependent, homophilic interactions, appears to be complex. Although a decrease of E-cadherin would be expected with invasive tumour growth in advanced primary melanoma and eventually in metastasis, surprisingly an increase is found, whereas alpha- and beta-catenin, (cytoplasmic) molecules functionally associated with E-cadherin, are detected in all benign and malignant lesions. A possible interpretation includes a difference in the morphogenesis and function of melanocytic cells, compared with epithelial cells. Further research is needed to clarify the role of E-cadherin/catenin during melanoma progression.