Fucosylation of Disaccharide Precursors of Sialyl LewisX Inhibit Selectin-mediated Cell Adhesion

We showed previously that HL-60 and F9 mouse embryonal carcinoma cells will take up and deblock peracetylated 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 LewisX(sLex)-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, GlcNAcβ1–3Gal-NM generated Galβ1–4GlcNAcβ1–3Gal-NM, Galβ1–4(Fucα1–3)GlcNAcβ1–3Gal-NM, NeuAcα2–3Galβ1–4GlcNAcβ1–3Gal-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 sLex 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.