INHIBITION OF METASTASIS BY A DIALYZABLE FACTOR IN FETAL BOVINE SERUMIN B16 MELANOMA-CELLS

Fetal bovine serum (FBS) supplemented to the culture medium inhibited the metastasis of B16BL6 melanoma cells in a dose-dependent manner. Th is metastasis-inhibiting activity was accompanied by growth-promoting activity, up to the concentration of 10% FBS, However, among the clone s isolated from B16BL6 cells, there were clones in which FBS significa ntly inhibited the metastasis without promoting their growth. Dialysis (cutoff M.W, 8000 Da) removed the metastasis-inhibiting activity but not the growth-promoting activity from FBS. These results indicate tha t FBS has metastasis-inhibiting activity which is independent of growt h-promoting activity, and that the metastasis-inhibiting activity is c arried by molecules removed by dialysis.