Fucosylation of disaccharide precursors of sialyl Lewis(X) inhibit selectin-mediated cell adhesion

We showed previously that HL-60 and F9 mouse embryonal carcinoma cells will take up and deblock per-acetylareal Galβ1-4GlcNAcβ-O- naphthalenemethanol (Galβ1-4GlcNAc-NM) and use the disaccharide as a primer of oligosaccharide chains (Sarkar, A. K., Fritz, T. A., Taylor, W. H., and Esko, J. D. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 3323-3327). We now report that another disaccharide, acetylated GlcNAcβ1-3Gal- naphthalenemethanol (GlcNAcβ1-3Gal-NM), has even greater potency and that both compounds will inhibit sialyl Lewis(X) (sLe(x))-dependent cell adhesion. When fed to U937 cells, acetylated forms of Galβ1-4GlcNAc-NM and GlcNAcβ1- 3Gal-NM primed oligosaccharides in a dose-dependent manner. Analysis of compounds assembled on Galβ1-4GlcNAc-NM showed only one product, namely Galβ1-4(Fucα1-3)GlcNAc-NM. In contrast, Glc-NAcβ1-3Gal-NM generated Galβ1-4GlcNAcβ1-3Gal-NM, Galβ1-4(Fucα1-3)GlcNAβ1-3Gal-NM, NeuAcα2- 3Galβ-1-4GlcNAcβ1-3Gal-NM, and NeuAcα2-3Galβ1-4(Fucα1-3)GlcNAcβ1-3Gal- NM. Both compounds decreased the incorporation of [³H]fucose into cellular glycoconjugates, without affecting the incorporation of [³H]mannosamine, a precursor of sialic acid residues. Moreover, the overall extent of sialylation was not affected based on the reactivity of cells to fluorescein isothiocyanate-conjugated Maackia amurensis lectin. Priming inhibited expression of sLe(x) on cell surface glycoconjugates, which reduced E- selectin-dependent cell adhesion to tumor necrosis factor-α-activated human umbilical vein endothelial cells. GlcNAcβ1-3Gal-NM and Galβ1-4GlcNAc-NM represent starting points for making enzyme-specific, site-directed inhibitors of glycosyltransferases that could act in living cells.