Characteristics of carcinoembryonic antigen (CEA) expressed in different cell types: evidence that CEA can function as an adhesion molecule and as a repulsion molecule.

The characteristics of carcinoembryonic antigen (CEA) molecules expressed by different cell types have been examined using cDNA transfection into cells of epithelial, neuroectodermal and hematopoietic origin. Variability in the CEA molecules was observed in terms of monoclonal antibody binding, apparent molecular weight and sialic acid content, although this was not cell type specific. CEA was found to mediate homotypic as well as heterotypic intercellular adhesion independently of the cell type and despite differences in the sialic acid content. Although CEA was shown to function as a homophilic cell adhesion molecule in most cells, expression of CEA in one cell line led to a reduction in both homotypic and heterotypic cell adhesion, suggesting that it can under certain circumstances also function as a repulsion molecule.