Biological and enzymatic features of human melanoma clones with different invasive potential.

Cell clones derived from a human melanoma metastasis selected for different integrin profiles were examined in vitro for invasive potential and biological and biochemical features potentially related to this process. Clones which expressed high levels of integrins showed high invasive potential, extracellular matrix degradation, and adhesion to gelatin-coated substrates. A correlation was also found between invasiveness and intracellular and extracellular plasminogen activator activity. Heparanase and collagenase type IV activities were apparently unrelated to invasiveness. gamma-Glutamyl transferase (GGT) activity was high in highly invasive clones, whereas melanin content was high in slightly invasive clones. Heterogeneity was also observed in cellular parameters such as cell dimensions, growth features and DNA index. The intrinsic biological and biochemical heterogeneity of a cell population derived from a single metastasis may be responsible for the different behaviour of clones, regardless of their invasive potential. Since slightly invasive cells are more differentiated than highly invasive cells, malignancy and differentiation are inversely correlated in such human melanoma clones.