Colon carcinoma cell glycolipids, integrins, and other glycoproteins mediate adhesion to HUVECs under flow

Abstract

This study was undertaken to investigate the molecular constituents mediating LS174T colon adenocarcinoma cell adhesion to 4-h TNF-α-stimulated human umbilical vein endothelial cells (HUVECs) under flow. At 1 dyn/cm2, ∼57% of cells rolled and then became firmly adherent, whereas others continuously rolled on endothelium. Initial cell binding was primarily mediated by endothelial E-selectin. By using neuraminidase, glycolipid biosynthesis inhibitor d,l-threo-1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol · HCl, trypsin, and flow cytometry, LS174T cells were shown to express sialyl Lewisx(sLex)- and di-sLex-decorated, but not sLea-decorated, glycolipid and glycoprotein ligands for E-selectin. The cells preferentially employed sialylated glycoproteins over glycolipids in adhesion as measured by conversion of rolling to firm adhesion, resistance to detachment by increased shear stress, and rolling velocity. However, a nonsialylated E-selectin counterreceptor also exists. Furthermore, LS174T α2, α6, and β1integrins support a minor pathway in adhesion to HUVECs. Finally, tumor cell attachment specifically increases HUVEC endocytosis of E-selectin. Altogether, the data indicate the complexity of carcinoma cell-endothelium adhesion via sialylated glycoconjugates, integrins, and their respective counterreceptors.