Adhesion of human uroepithelial cells to E-selectin: Possible involvement of sialosyl LewisA-ganglioside

In a previous study we showed that tumorigenic and invasive human uroepithelial cell lines are characterized by the presence of sialosyl Le^a (sLe^a) ganglioside. Our data suggested that expression of this glycolipid correlated with acquisition of the malignant phenotype by human urothelial cells. To evaluate the postulated adhesion function of sLe^a antigen, we studied the adherence of 6 human urothelial cell lines with different expressions of this carbohydrate structure to E-selectin-expressing CHO cells. The only cell line that bound specifically to E-selectin was Hu 1703He, which expressed the highest level of sLe^a antigen. The involvement of carbohydrate-E-selectin interaction in the adhesion of Hu 1703He cells was indicated by the following facts: (i) anti-E-selectin monoclonal antibody (MAb) completely abolished binding to E-selectin-expressing CHO cells; (ii) removal of sialic acid from Hu 1703He cells highly decreased the adhesion. Adhesion correlated with the presence of several sLe^a-carrying glycoproteins, which was shown by immunoblotting of Hu 1703He cell lysate with anti-sLe^a MAb 19-9. The binding of antibody was abolished when cell lysate was treated with O-sialoglycoprotein endopeptidase, suggesting that sLe^a is present on O-linked oligosaccharides. However, incubation of Hu 1703He cells with O-sialoglycoprotease had no effect on adhesion to E-selectin or on binding of 19-9 MAb to the cell surface. Our data suggest that (i) protein-bound sLe^a oligosaccharides represent only a minor portion of whole sLe^a antigen produced by uroepithelial cells; (ii) effective binding to E-selectin occurs when sLe^a oligosaccharide present on cell-surface glycosphingolipids is expressed in high density since the cell lines with moderate expression of sLe^a ganglioside did not bind to E-selectin-transfected CHO cells. © 1996 Wiley-Liss, Inc.