Human colon cancer cells express multiple glycoprotein ligands for E-selectin

The interaction between the colon tumor cell surface and the endothelial ce ll layer is an important component of tumor intravasation, extravasation, a nd metastasis. Multiple studies suggest that tumor cells may bind to E-sele ctin expressed on endothelial cells during these processes. To identify pos sible E-selectin ligands on tumor cells that may participate in this mechan ism, we used E-selectin-Ig chimera affinity chromatography to isolate glyco proteins from the human colon cancer cell line Colo-205. Binding of these c ells to E-selectin was specific, required the presence of calcium, and coul d be blocked by antibodies against E-selectin. We identified LAMP-1 (lysoso mal membrane glycoprotein-l), LAMP-2, and two high molecular weight glycopr oteins (>400 kDa and 300 kDa) as the main E-selectin ligands on Cole-205 ce lls. Treatment of the cells with N-glycanase and O-sialoglycoprotease aboli shed their binding to E-selectin. The high MW glycoproteins contained sialy l Lewis X and/or sialyl Lewis A glycoconjugates, and appeared to be either alternatively spliced or alternatively glycosylated forms of MUC-1 (mucin-1 ).