Classification and localisation of carcinoembryonic antigen (CEA) related antigen expression in normal oesophageal squamous mucosa and squamous carcinoma.

Using a panel of carcinoembryonic antigen (CEA) related antibodies in normal oesophageal squamous mucosa CEA expression is present on suprabasal 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 confined to cells in foci of squamous differentiation. A shift from membranous localisation to predominant cytoplasmic overexpression is shown between normal and malignant squames using confocal microscopy. The recognition of an adhesive role for CEA and a role in enhancing distant metastases in those tumours expressing CEA highlights the importance of recording CEA expression and changes in subcellular distribution between normal and malignant tissues; CEA expression in oesophageal squamous mucosa has not been well recognised previously and changes in expression may prove of great significance in the spread and dissemination of squamous carcinoma.