CDX-2 and HER-3 expression in canine gastric and colorectal adenocarcinomas.

CDX-2 is used as a specific cell marker for human intestinal adenocarcinoma. In human studies, HER-3 overexpression predicts poor survival for patients with various cancers including gastric cancer. Gastrointestinal adenocarcinoma is less common in dogs than in man and the expression of immunological markers by the canine tumours has not yet been extensively studied. CDX-2 and HER-3 expression was determined in 18 canine gastrointestinal adenocarcinomas: 13 were of colorectal origin and five were of gastric origin. CDX-2 expression was predominantly observed in the nuclei of normal colonic epithelium and in neoplastic epithelium and neoplastic gastric epithelial cells that which had metastasized to the gastric lymph node. CDX-2 was expressed in 11 of 13 (84.6%) colorectal adenocarcinomas and in all five (100%) gastric adenocarcinomas. HER-3 was consistently expressed in the cytoplasm of neoplastic epithelial cells. HER-3 expression was detected in 12 of 13 (92.3%) colorectal and in all five (100%) gastric adenocarcinomas. CDX-2 and HER-3 may be useful markers for canine gastrointestinal adenocarcinoma.