The role of fibronectin in adhesion of metastatic melanoma cells to endothelial cells and their basal lamina

Abstract

Vascular endothelial cells synthesize an extracellular matrix or basal lamina composed of collagens, proteoglycans and glycoproteins such as fibronectin (FN). Using affinity-purified anti-FN, we have examined the role of FN in adherence of metastatic B16 melanoma cells to endothelial cell monolayers which lack FN on apical cell surfaces and to their basal lamina which contains FN. B16 melanoma cells, which do not contain significant amounts of FN, attached at much higher rates to endothelial basal lamina and polyvinyl-immobilized FN compared with intact endothelial cell monolayers. Anti-FN failed to inhibit attachment of melanoma sublines of low (B16-F1) or high (B16-F10) metastatic potential to intact endothelial cell monolayers, inhibited slightly B16 cell attachment to basal lamina and completely abolished attachment of B16 cells to polyvinyl-immobilized FN. The antibiotic tunicamycin which inhibits glycosylation of B16 cell surface glycoproteins and blocks experimental metastasis [18] inhibited B16 attachment to endothelial cells, basal lamina and immobilized FN. The results suggest that FN mediates, only in part, the adhesion of B16 melanoma cells to basal lamina through glycoprotein receptors on B16 cells.