Selectin Ligand Expression Regulates the Initial Vascular Interactions of Colon Carcinoma Cells: THE ROLES OF CD44V AND ALTERNATIVE SIALOFUCOSYLATED SELECTIN LIGANDS

• Published in: The Journal of biological chemistry Vol. 282; no. 6; pp. 3433 - 3441
• Main Authors: Napier, Susan L, Healy, Zachary R, Schnaar, Ronald L, Konstantopoulos, Konstantinos
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 09-02-2007
• Subjects: Animals; Cell Line, Tumor; CHO Cells; Colonic Neoplasms - blood supply; Colonic Neoplasms - metabolism; Colonic Neoplasms - pathology; Cricetinae; Cricetulus; Fucose - metabolism; Humans; Hyaluronan Receptors - biosynthesis; Hyaluronan Receptors - genetics; Hyaluronan Receptors - metabolism; Hyaluronan Receptors - physiology; Ligands; Mutagenesis, Site-Directed; N-Acetylneuraminic Acid - metabolism; Neoplasm Metastasis - pathology; P-Selectin - metabolism; Protein Isoforms - genetics; Protein Isoforms - metabolism; Protein Isoforms - physiology; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M607219200

Selectin-mediated binding of tumor cells to platelets, leukocytes, and vascular endothelium may regulate their hematogenous spread in the microvasculature. We recently reported that CD44 variant isoforms (CD44v) on LS174T colon carcinoma cells possess selectin binding activity. Here we extended those findings by showing that T84 and Colo205 colon carcinoma cells bind selectins via sialidase-sensitive O-linked glycans presented on CD44v, independent of heparan and chondroitin sulfate. To assess the functional role of CD44v in selectin-mediated binding, we quantified the adhesion to selectins of T84 cell subpopulations sorted based on their CD44 expression levels and stable LS174T cell lines generated using CD44 short hairpin RNA. High versus low CD44-expressing T84 cells tethered more efficiently to P- and L-selectin, but not E-selectin, and rolled more slowly on P- and E-selectin. Knocking down CD44 expression on LS174T cells inhibited binding to P-selectin and increased rolling velocities over P- and L-selectin relative to control-transfected cells, without affecting tethering and rolling on E-selectin, however. Blot rolling analysis revealed the presence of alternative sialylated glycoproteins with molecular masses of ~170 and ~130 kDa, which can mediate selectin binding in CD44-knockdown cells. Heparin diminishes the avidity of colon carcinoma cells for P- and L-selectin, which may compromise integrin-mediated firm adhesion to host cells and mitigate metastasis. Our finding that CD44v is a functional P-selectin ligand on colon carcinoma provides a novel perspective on the enhanced metastatic potential associated with tumor CD44v overexpression and the role of selectins in metastasis.