CEA

Abstract

Carcinoembryonic antigen (CEA) was first described in 1965 by Gold and Freedman (Gold and Freedman, J Exp Med 122:467–481, 1965a; J Exp Med 121:439–462, 1965b). This 180,000 Da glycoprotein earned its name due to its presence in neoplastic and embryonic gastrointestinal tissues (Martin et al., Cancer 37:62–81, 1976). CEA is overexpressed on most adenocarcinomas of the colon, rectum, stomach, and pancreas, as well as breast cancers and non-small cell lung cancers, and as such is a “tumor-associated antigen” (TAA) (Chevinsky, Semin Surg Oncol 7:162–166, 1991). It has also been identified in small amounts on normal adult colonic mucosa (Fritsche and Mach, Immunochemistry 14:119–127, 1977). The family belongs to the immunoglobulin superfamily and resides on the long arm of chromosome 19. CEA protein shares significant amino acid homology with a nonspecific cross-reacting antigen that is found on normal granulocytes (Engvall et al., Proc Natl Acad Sci U S A 75:1670–1674, 1978). As an intercellular adhesion molecule, CEA may contribute to the formation of metastasis; there is a correlation between serum CEA in patients with cancer and the incidence of hepatic metastases, but this could also simply reflect tumor burden (Steele et al., Ann Surg 196:162–169, 1982; Yeatman et al., Ann Surg 210:505–512, 1989). In normal colonic epithelium, CEA is localized to the luminal surface, an arrangement that suggests that it contributes to spatial orientation of colonocytes and that it may also function to preserve the adult gut mucosal barrier (Marshall, Oncology (Williston Park) 19:1557–1565, 2005). In tumor cells, however, CEA is irregularly distributed throughout the cell membrane.