Low Colony Formation in Vivo and in Culture as Exhibited by Metastatic Melanoma Cells Selected for Reduced Homotypic Aggregation

Abstract

A subpopulation of cells unable to aggregate in the presence of a high concentration of asialofetuin (400 µg/ml) has been isolated from the murine B16-F1 melanoma cells which aggregate readily at low asialofetuin concentrations (>0.3 µg/ml). Cells of this variant cell line, designated B16-F1-NA, exhibited also a reduced tendency to undergo homotypic aggregation in the presence of syngeneic serum. In culture, the B16-F1-NA cells spread on solid substrata more than the B16-F1, formed more focal contacts, and proliferated at a slower exponential rate. The pattern of the major cell surface proteins and glycoproteins was similar in the parental and variant cells except for a minor glycoprotein with a molecular weight of 150,000 which was labeled more intensely on the B16-F1 than on the B16-F1-NA cells. Colony formation in semisolid medium and the development of experimental metastases in the lungs of syngeneic mice were markedly reduced in the B16-F1-NA as compared with the parental cells. It is suggested that the ability to undergo aggregation in the presence of glycoproteins is an important property of malignant cells which may influence anchorage-independent growth and the formation of metastases.