The in vitro invasiveness and interactions with laminin of K-1735 melanoma cells. Evidence for different laminin-binding affinities in high and low metastatic variants.

The invasive and metastatic characteristics of cloned cells derived from the K-1735 murine melanoma were investigated. Cell lines which are highly metastatic in mice were found to be invasive in vitro, and to show an enhanced attachment to, spreading on and migration toward laminin. As attachment, spreading and directional migration are thought to be receptor-mediated events, the binding of laminin to these cells was studied. Biotinylated laminin was used to evaluate receptor binding by fluorescence activated cell sorting (FACS) and this method was compared with that in which the binding of radioactive laminin is measured. Both studies revealed that metastatic K-1735 cells (a) have more receptors for laminin compared with non-metastatic cells and (b) exhibit a second population of low-affinity binding sites not present on the non-metastatic cells. The differences in receptor number and type may account for the greater interaction of metastatic cells with laminin and their invasive phenotype.