CD44 is a cellular adhesion molecule expressed in many different types of cells that may be a receptor for hyaluronic acid, laminin, collagen or fibronectin. In this study, we determined whether CD44 participated in the adhesion of three human colorectal carcinoma cell lines (KM-12c, CCL 188 and MIP-101) to laminin, collagen and hyaluronic acid. All lines were positive for the epithelial form of CD44 (CD44E) with a molecular weight of approximately 160 kD. All of them bound significantly to laminin and type IV collagen but not to hyaluronic acid in a solid phase adhesion assay. Three monoclonal antibodies to CD44 (Hermes 1, Hermes 3 and J173) significantly blocked the binding of colorectal carcinoma lines to laminin and collagen whereas another antibody to CD44 (50B4) bound to cells but did not inhibit adhesion. Only Hermes 1 completely abolished the binding to hyaluronic acid by a human B lymphoblastoid cell line, JY, that expressed the 90 kD haematopoietic form of CD44. Soluble hyaluronate inhibited the adhesion of JY cells to solid phase hyaluronate but did not inhibit adhesion to laminin and collagen by the colorectal carcinoma lines. Thus, (a) CD44E participates in the adhesion of colorectal carcinoma cells to laminin and type IV collagen and (b) the binding site for laminin and collagen on CD44E is different from the site for hyaluronic acid.
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