Abstract
Two of the more important steps in blood-borne tumor metastasis are attachment of the circulating malignant cells to the vascular endothelium and subsequent extravasation or invasion out of the blood vessel. A model for this process has been developed using cultured monolayers of vascular endothelial cells that synthesize a basal lamina or extracellular matrix (Kramer and Nicolson, Proc Natl Acad Sci USA 76:504, 1979). We have used this model to study metastatic tumor cell-endothelial cell interactions such as attachment to endothelial cells and their subsequent retraction and exposure of endothelial basal lamina as well as the interactions of metastatic tumor cells with the basal lamina leading to invasion and solubilization of this extracellular matrix. Morphological, immunological, and enzymological analysis of these steps in the metastatic process can be obtained using the vascular endothelial cell monolayer model for attachment and invasion.