Patterns of alpha- and beta-catenin and E-cadherin expression in colorectal adenomas and carcinomas.

Previous in vitro and in vivo model studies have shown that when E-cadherin expression in carcinoma cells is reduced, invasive behaviour ensues. The situation in human cancer in vivo, however, appears to be more complex, as immunohistochemically determined E-cadherin expression in various carcinomas, including colorectal cancer, does not always correlate with invasive growth. Loss of cell adhesion during invasion in spite of E-cadherin expression might be associated with a defective cadherin-catenin complex. The expression of alpha- and beta-catenin in comparison with E-cadherin was therefore examined in colorectal adenomas and carcinomas and in lymph node and liver metastases. In normal colonic mucosa, alpha- and beta-catenin immunoreactivity occurred along the lateral plasma membranes of the epithelial cells, in a pattern identical to E-cadherin staining. A similar pattern was found in colorectal adenomas and in most malignancies. In general, in neoplastic epithelia, the majority of the cancer cells displayed a normal (matching) pattern of E-cadherin and catenin expression. It is concluded that the patterns of expression of E-cadherin and alpha- and beta-catenin are very similar in colorectal neoplasms. This observation indicates that invasion in colorectal cancer is not paralleled by consistent loss of expression of the components of the cadherin-catenin complex.