N-linked sugar chains of mouse B16 melanoma cells and their low-metastasizing variant selected by wheat germ agglutinin

Abstract

The N-linked sugar chains of metastasizing mouse B16 melanoma cells (F1) and their wheat germ agglutinin-resistant variant (Wa4-b1) showing a dramatic decrease in metastasizing and tumorigenic potentials were liberated from their membrane glycoproteins by hydrazinolysis, and their structures were comparatively analysed. The results indicated that both cell lines contain high-mannose-type and bi-, tri- and tetraantennary complex-type oligosaccharides, and their ratios are similar. However, outer chain moieties of tri- and tetraantennary oligosaccharides of the variant are extensively fucosylated, resulting in the formation of X-antigenic determinants, Gal beta 1----4(Fuc alpha 1----3)GlcNAc. Oligosaccharides containing X-antigenic determinants amounted to 71% of the total complex-type oligosaccharides. Fucosylation occurs on every N-acetyllactosamine unit and the number of the determinants ranges from one to three in triantennary oligosaccharides and one to four in tetraantennary oligosaccharides. The determinants occur predominantly in non-sialylated forms, although some are in sialylated forms. Oligosaccharides containing non-sialylated X-antigenic determinants and those containing sialylated X-antigenic determinants are approximately in the ratio 6:1. Since no significant difference was found in the extent of branching of complex-type oligosaccharides of the two cell lines, it is suggested that non-fucosylated outer chains are important for the expression of metastasizing potential by the tumour cells.