Possible function of CEA as cell-contact inhibitory molecule.

Ever since it was discovered that CEA, as member of the CEA-gene family, is part also of the Ig-supergene family, to which molecules involved in cell interactions like cell adhesion or cell recognition belong, great efforts were made to prove that CEA is also an adhesion molecule. At present this seems to be an accepted fact. In the present study we advance a different theory which is based on the expression pattern of CEA during ontogeny and in malignancy and which is suggestive of CEA functioning more as a signal protein prohibiting further cell/cell contact rather than as an adhesion molecule. In the malignant state the expression of this molecule on the surface of tumor cells would facilitate migration and motility, i.e., metastases formation. Furthermore it would prevent a tight contact between cytotoxic effector cells and CEA expressing target cells.