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

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 Lewis^x(sLe^x)- and di-sLe^x-decorated, but not sLe^a-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 β₁, integrins 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.