CD44 PARTICIPATES IN THE ADHESION OF HUMAN COLORECTAL-CARCINOMA CELLSTO LAMININ AND TYPE-IV COLLAGEN

CD44 is a cellular adhesion molecule expressed in many different types of cells that may be a receptor for hyaluronic: acid. laminin, collag en or fibronectin. In this study, we determined whether CD44 participa ted in the adhesion of three human colorectal carcinoma cell lines (KM -12c, CCL 188 and MIP-101) to laminin, collagen and hyaluronic acid. A ll lines were positive for the epithelial form of CD44 (CD44E) with a molecular weight of approximately 160 kD. All of them bound significan tly to laminin and type IV collagen but not to hyaluronic acid in a so lid 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 CD 44 (50B4) bound to cells but did not inhibit adhesion. Only Hermes 1 c ompletely abolished the binding to hyaluronic acid by a human B lympho blastoid cell line, JY, that expressed the 90 kD haematopoietic form o f CD44. Soluble hyaluronate inhibited the adhesion of JY cells to soli d phase hyaluronate but did not inhibit adhesion to laminin and collag en by the colorectal carcinoma lines. Thus, (a) CD44E participates in the adhesion of colorectal carcinoma cells to laminin and type IV coll agen and (b) the binding site for laminin and collagen on CD44E is dif ferent from the site for hyaluronic acid.