In vitro motility of BSp73 rat tumor cells with different metastatic ability

The highly metastatic and nonmetastatic variants of the rat tumor BSp73 have been tested for motility in vitro by a phagokinetic assay. Surprisingly, the nonmetastatic variant is locomotional, whereas the highly metastatic variant exhibited stationary motility only. Soluble factors of normal rat serum and medium conditioned by regenerating normal rat lung, or solid constituents of the extracellular matrix material which was exudated by normal rat lung fibroblasts or bovine cornea endothelial cells as well as collagen type III could not stimulate locomotory ability in these tumor cells. However, by contact to rat lung cells they acquired passive mobility. The significance of these cellular properties for their metastatic behavior is discussed.