Enhanced sialylation of the K 562 cell surface membrane glycoconjugates induced by adriamycin.

ABSTRACT

The antitumor agent Adriamycin (ADM) increases the sialic acid content of K 562 cell plasma membrane glycoconjugates. Total and neuraminidase-sensitive sialic acid are enhanced 3 to 4 times when expressed per 10(6) cells. This fact is a consequence of an increase in cell surface and in plasma membrane sialic acid density. Protein-bound and lipid-bound sialic acid are increased in the same way and exhibit the same ratio 90/10. After external radiolabelling by periodide-borotritide and neuraminidase-galactose oxidase-borotritide treatment, only some quantitative changes can be observed. Fractionation of gangliosides by thin layer chromatography gives the same results. Further experiments lead to the following conclusions: the hypersialylation cannot be explained by a G2-block in the cell cycle induced by ADM; it is not a consequence of a differentiation process; it is not observed in a population of adriamycin-resistant K 562 cells and can therefore be considered as a metabolic event linked to the cytotoxic activity of ADM.