Cell adhesion and experimental metastasis: a study using the B16 malignant melanoma model system.

The adhesive properties of B16F1 and B16F10 cells have been studied following their rates of attachment to various substrates and by analysis of their rates of aggregation within the defined environment provided by a cone and plate viscometer. Contrary to previous reports, we found that the B16F10 cells (with significant lung-colonizing potential following tail vein injection) were less homotypically adhesive than B16F1 cells (which colonize lungs poorly). The adhesiveness of B16F10 cells approached that of B16F1 cells only under conditions (low shear, low cell number) where cell collisions were thought to be so few that quantitative differences in aggregation rate could not be determined. B16F1 cells also adhered more to lung cells than did B16F10 cells when assessed by aggregation rate. However, analysis of aggregate composition in which one cell type had been fluorescently labelled showed that B16F10 cells actually formed more mixed aggregates with lung cells than did B16F1 cells. There was no significant difference in the adhesiveness of B16F1 or B16F10 cells to liver cells as assessed by aggregation rate. Analysis of aggregate composition under these circumstances, however, showed that B16F10 cells formed fewer mixed aggregates with liver cells than did B16F1 cells. These results are consistent with the possibility that metastatic cells need to display poor homotypic adhesiveness in order to detach from the primary but enhanced heterotypic adhesiveness in order to colonize specific organs.