CDX1 PROTEIN EXPRESSION IN NORMAL, METAPLASTIC, AND NEOPLASTIC HUMAN ALIMENTARY-TRACT EPITHELIUM

Background & Aims: CDX1 is an intestine-specific transcription factor expressed early in intestinal develop ment that may be involved in reg ulation of proliferation and differentiation of intestinal epithelial cells, We examined the pattern of CDX1 protein expression in metaplast ic and neoplastic tissue to provide insight into its possible role in abnormal differentiation. Methods: Tissue samples were stained by immu nohistochemistry using an affinity-purified, polyclonal antibody again st a peptide epitope of CDX1. Results: Specific nuclear staining was f ound in epithelial cells of the small intestine and colon. Esophagus a nd stomach did not express CDX1 protein; however, adjacent areas of in testinal metaplastic tissue intensely stained for CDX1, Adenocarcinoma s of the stomach and esophagus had both positive and negative nuclear staining for CDX1, Colonic epithelial cells in adenomatous polyps and adenocarcinomas had a decreased intensity of staining compared with no rmal colonic crypts in the same specimen, Conclusions: CDX1 may be imp ortant in the transition from normal gastric and esophageal epithelium to intestinal-type metaplasia. The variability in expression of CDX1 in gastric and esophageal adenocarcinomas suggests more than one pathw ay in the develop ment of these carcinomas. The decrease of CDX1 in co lonic adenocarcinomas may indicate a role for CDX1 in growth regulatio n and in the maintenance of the differentiated phenotype.