The expression of CD66a and possible roles in colorectal adenoma and adenocarcinoma

The aim of our study was to analyze the expression and possible role of CD66a in colorectal adenoma and adenocarcinoma and the relationship between its expression and pre-operation serum carcinoembryonic antigen (CEA) level and tumor stage in patients with colorectal adenocarcinomas.

Paraffin-embedded sections from 184 patients including 42 colorectal adenomas with low-grade dysplasia, 43 adenomas with high-grade dysplasia, and 99 adenocarcinomas were collected for this study. Immunohistochemical analysis was performed, and the expression and the location of CD66a were evaluated and were correlated with beta-catenin nuclear expression.

The expression of CD66a was found not only in the apical membrane of neoplastic glands but also in secretion within the lumen of the neoplastic glands including adenomas and adenocarcinomas. Expressions of secreted CD66a were of higher level in adenocarcinoma than in adenoma with high-grade dysplasia and adenoma with low-grade dysplasia (p < 0.0001). High expression of secreted CD66a was also associated with tumor stage, invasion, and pre-operation serum CEA level of patients with colorectal adenocarcinoma.

This study implied that CD66a can function both as an epithelial cell adhesion protein or alternatively as secreted CD66a. In addition, a high expression of CD66a was significantly correlated with tumor invasion, stage, and pre-operation serum CEA level.