VARIATIONS IN THE SIALIC-ACID COMPOSITIONS IN GLYCOPROTEINS OF MOUSE ASCITES TUMOR-CELL SURFACES

Sialic acid removable by Vibrio cholerae neuraminidase from four TA3 mammary carcinoma ascites sublines of the strain A mouse and six TA3-Ha/A.CA hybrid cell lines, in ascites form, resulting from fusion of TA3-Ha cells and normal fibroblasts of the A.CA mouse and adapted for growth in the strain A mouse [Klein, G., et al. (1972) J. Exp. Med. 135, 839], consisted of mixtures of N-acetyl-neuraminic acid and N-glycolylneuraminic acid (NeuNGl). Total cell-surface sialic acid (μg/109 cells) and proportion of NeuNGl (%) averaged, respectively, as follows: TA3-St, 270 μg, 20%; TA3-Ha, 620 μg, 7%; TA3-MM/1, 850 μg, 12%; TA3-MM/2,1200 μg, 12%; TA3-Ha/A.CA/3B, 700 μg, 13%; TA3-Ha/A.CA/4, 870 μg, 19%; TA3-Ha/A.CA/6, 1180 μg, 17%; TA3-Ha/A.CA/7, 910 μg, 38%; TA3-Ha/A.CA/10, 470 μg, 17%; and TA3-Ha/A.CA/11, 850 μg, 6%. Fractions of effluents obtained by gel filtration chromatography of glycopeptides cleaved from viable cells by proteolysis were analyzed for carbohydrate composition and proportion of NeuNGl. Glycopeptide fractions from the same cells possessed markedly different proportions of NeuNGl. The proportion of NeuNGl increased consistently with the percent of mannose in the carbohydrate moiety and decreased with the percent of N-cetylgalactosamine and with the apparent molecular weights (by gel filtration). It was concluded that, in the TA3 tumor system, the proportion of NeuNGl in the sialic acid of cell surface glycoproteins of an ascites cell line correlates directly with the proportion of N-glycosyl-linked carbohydrate chains in the glycoproteins. © 1979, American Chemical Society. All rights reserved.