Immunohistological analysis of E-cadherin, alpha-, beta- and gamma-catenin expression in colorectal cancer: implications for cell adhesion and signaling.

Intercellular adhesion mediated by the E-cadherin/catenin complex is a prerequisite for epithelial integrity and differentiation. In carcinomas, E-cadherin function is frequently disturbed, and has been suggested to increase invasion and metastasis of tumour cells. beta-catenin has also been implicated in signaling pathways essential for tumour formation. We analysed the E-cadherin/catenin adhesion system of colorectal tumours at different clinical stages. In primary carcinomas (n = 91), there was a frequent reduction in E-cadherin (44%) and alpha-catenin expression (36%). In contrast, beta-catenin and gamma-catenin expression were seldom reduced (4% and 15%, respectively). Similar expression patterns were observed in liver metastases from unrelated colorectal tumours (n = 27). There was a significant relationship between loss of E-cadherin and alpha-catenin expression and poorly differentiated (G3-4) tumours. Our results suggest that reduction of E-cadherin/alpha-catenin expression is a frequent event in primary and metastatic colorectal carcinomas. Furthermore, beta-catenin expression remains normal in colorectal cancer, suggesting the essential role of beta-catenin in signaling pathways.