Carbohydrate-binding protein 35 is the major cell-surface laminin-binding protein in colon carcinoma
E. C. Lee, H. J. Woo, C. A. Korzelius, G. D. Steele Jr and A. M. Mercurio
Laboratory of Cancer Biology, Deaconess Hospital, Harvard Medical School, Boston, Mass 02115.
The interaction of tumor cells with laminin is thought to be critical in
invasion and metastasis. We found that an endogenous lectin,
carbohydrate-binding protein 35 (CBP-35), is the major laminin-binding
protein on human colon carcinoma cells and that its surface expression
suggests involvement in metastasis. We identified CBP-35 by
laminin-affinity chromatography and immunoblotting. Surface expression of
CBP-35 on eight human colon carcinoma cell lines was compared by flow
cytometry. Poorly differentiated cell lines and DLD-2, a signet-ring
carcinoma cell line, expressed more surface CBP-35 than well-differentiated
cell lines. Poorly differentiated cell lines and DLD-2 are characterized as
aggressive cell lines because they adhere to and invade through
reconstituted basement membrane significantly better than
well-differentiated cell lines. These data suggest that CBP-35 is involved
in tumor cell-basement membrane interactions and that an increase in CBP-35
surface expression may facilitate metastatic potential of colon carcinoma
cells.
