ADHESION OF HUMAN UROEPITHELIAL CELLS TO E-SELECTIN - POSSIBLE INVOLVEMENT OF SIALOSYL LEWIS(A)-GANGLIOSIDE

In a previous study we showed that tumorigenic and invasive human uroe pithelial cell lines are characterized by the presence of sialosyl Le( a) (sLe(a)) ganglioside. Our data suggested that expression of this gl ycolipid correlated with acquisition of the malignant phenotype by hum an urothelial cells. To evaluate the postulated adhesion function of s Le(a) antigen, we studied the adherence of 6 human urothelial cell lin es with different expressions of this carbohydrate structure to E-sele ctin-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 bin ding to E-selectin-expressing CHO cells; (ii) removal of sialic acid f rom 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 trea ted 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-select in or on binding of 19-9 MAb to the cell surface. Our data suggest tha t (i) protein-bound sLe(a) oligosaccharides represent only a minor por tion of whole sLe(a) antigen produced by uroepithelial cells; (ii) eff ective binding to E-selectin occurs when sLe(a) oligosaccharide presen t on cell-surface glycosphingolipids is expressed in high density sinc e the cell lines with moderate expression of sLe(a) ganglioside did no t bind to E-selectin-transfected CHO cells. (C) 1996 Wiley-Liss, Inc.