CLASSIFICATION AND LOCALIZATION OF CARCINOEMBRYONIC ANTIGEN (CEA) RELATED ANTIGEN EXPRESSION IN NORMAL ESOPHAGEAL SQUAMOUS MUCOSA AND SQUAMOUS CARCINOMA

Using a panel of carcinoembryonic antigen (CEA) related antibodies in normal oesophageal squamous mucosa CEA expression is present on suprab asal squames localised to the cell membrane. Immunoblotting shows that this positivity is predominantly due to a glycoprotein of around 180 kDa representing CEA itself. Positivity in squamous carcinomas is conf ined to cells in foci of squamous differentiation. A shift from membra nous localisation to predominant cytoplasmic overexpression is shown b etween normal and malignant squames using confocal microscopy. The rec ognition of an adhesive role for CEA and a role in enhancing distant m etastases in those tumours expressing CEA highlights the importance of recording CEA expression and changes in subcellular distribution betw een normal and malignant tissues; CEA expression in oesophageal squamo us mucosa has not been well recognised previously and changes in expre ssion may prove of great significance in the spread and dissemination of squamous carcinoma.