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pubmed:abstractText |
The glycoproteins granule membrane protein 140 (GMP140), endothelial-leukocyte adhesion molecule 1 (ELAM-1), and Leu-8 are members of a family of glycoprotein receptors (selectins or LEC-CAMs) that play an important role in adhesive interactions between circulating leukocytes and vascular endothelium. Recently it has been reported that ELAM-1 is able to mediate the binding of the colon carcinoma cell line HT-29 to cytokine-activated vascular endothelium, suggesting that tumor cell adhesion to vascular endothelium, a prerequisite for tumor extravasation and metastasis, is in part the result of adhesive interactions between blood-borne tumor cells and cell surface proteins expressed by vascular endothelium. Here, using an approach in which soluble immunoglobulin chimeras of the GMP140 and ELAM-1 receptors were prepared and used to carry out immunohistological studies, we establish that GMP140 binds to tumor cells in a variety of human carcinoma tissue sections (colon, lung, and breast), whereas ELAM-1 binds exclusively to tumor cells in colon carcinoma tissue sections. In addition, GMP140 was found to bind to the cell surface of a number of cell lines derived from various carcinomas but not from melanomas, whereas ELAM-1 bound only colon carcinoma cell lines. We further investigated the nature of the ligands of GMP140 and ELAM-1 on the surface of the carcinoma cells and found that the GMP140 ligand on the surface of tumor cells appears to be distinct from that expressed on the myeloid cell line HL-60. Neuraminidase treatment of a breast carcinoma cell line does not affect, or in some instances increases, GMP140 binding, whereas it completely abolishes GMP140 binding to HL-60 cells. On the other hand, the ligand of ELAM-1 on both the colon carcinoma and HL-60 cells is neuraminidase sensitive in accord with its identification as sialyl-CD15. Parallel results were obtained with neuraminidase-treated frozen carcinoma tissue sections. The present findings form the basis for investigating the role of GMP140 in tumor invasiveness and metastasis.
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