Growth stage-dependent sialylation of tumor-associated embryonic substances on mouse ascites tumor cells.

It has been reported that sera from tumor-regressor mice contain a class of sugar-binding proteins which specifically bind to the tumor cell surface antigens when terminal sugar residues are deleted from the glycoprotein molecules of the antigens and thus agglutinate free-cell type tumor cells in vitro. Using such agglutination of tumor cells with appropriate regressor sera, sialylation of cross-reacting tumor-associated embryonic substances on the surface of various ascites tumor cells of mice was studied. The result showed that sialylation of tumor-associated embryonic substances in all cases took place at specific stages of cell growth after transplantation of the cells, while sialylation of other cellular components in general occurred throughout the growth stages. Marked differences was observed between timing of sialylation of tumor-associated embryonic substances of hyperdiploid tumor cells and that of hypotetraploid tumor cells.