Significance of Carbohydrate Antigen Sialyl-Lewis X, Sialyl-Lewis A, and Possible Unknown Ligands to Adhesion of Human Urothelial Cancer Cells to Activated Endothelium

Abstract

Objective: To assess the contribution of the carbohydrate antigens, sialyl-Lewis X (sLe^x) and sialyl-Lewis A (sLe^a), which are known to be ligands for E-selectin, to the adhesion between human urothelial cancer cells and cytokine-activated human endothelial cells. Materials and Methods: We studied the expression of sLe^x and sLe^a antigens of three bladder cancer cell lines (JTC 30, JTC 32, and T24) by flow cytometry and the adherence to interleukin 1β-activated human umbilical vein endothelial cells (HUVEC). Results: JTC 30 and JTC 32 cells expressed both sLe^x and sLe^a antigens, and showed adhesion to activated HUVEC, which was completely abolished by anti-E-selectin antibody. T24 cells expressed neither sLe^x nor sLe^a antigen, and did not adhere to activated HUVEC. Each of anti-sLe^a or anti-sLe^x antibody partially blocked the attachment of JTC 30 cells to activated HUVEC, and combination of these antibodies almost completely blocked the adhesion. The combination of antibodies did not significantly influence the adhesion of JTC 32 cells. Conclusion: These results indicate that both sLe^a and sLe^x carbohydrate antigens are involved in E-selectin-mediated adhesion of some urothelial cancers, and that there might be unknown ligands for E-selectin on urothelial cancer cells.