Carcinoembryonic Antigen (CEA {M}) Description
The CEA gene family belongs to the immunoglobulin gene superfamily (IgSF) and comprises a large number of genes. The cell surface associated CEA proteins are heavily glycosylated, abundantly expressed and multifunctional. The human carcinoembryonic antigen (CEA) family can be divided into two subgroups according to the means of anchorage of member glycoproteins to the cell membrane: glycophosphatidyl inositol (GPI) linkage and transmembrane linkage. GPI-linked CEA family members include CEA (CD66e), non-specific cross-reacting antigen (NCA, CD66c), CEA gene-family members 6 (CGM6, CD66b) and 2 (CGM2). Transmembrane-linked members include biliary glycoprotein (BGP, Human C-CAM-L and C-CAM-S, CD66a), CGM1(CD66d) and CGM7. Recent evidence suggests the GPI-linked members tend to be up-regulated in human tumors, whereas the transmembrane-linked members tend to be down-regulated. The CEA (CD66e) COL-1 clone shows no detectable reactivity for other CEA family members such as NCA or BGP. COL-1 is useful in detecting early foci of gastric carcinoma and distinguishing pulmonary adenocarcinomas from mesothelioma. It stains many types of adenocarcinoma, but does not stain benign glands, stroma, or malignant prostatic cells. Normal colon, without colon disease, is unreactive, but a weak reactivity appears in mucosa several centimeters remote from colon cancer.