E-cadherin and β-catenin expression in canine colorectal adenocarcinoma.

E-cadherin and its associated cytoplasmic proteins, including β-catenin, have been examined as potential oncogenic markers due to the significant correlation between tumour dedifferentiation and the invasive capacity of epithelial tumours. The purpose of this study was to evaluate the expression of E-cadherin and β-catenin in canine colorectal cancer using immunohistochemistry and to examine the relationship between this expression and various clinicopathological variables. The expression pattern of E-cadherin and β-catenin was investigated in 44 colorectal canine carcinomas. In the intestinal mucosa of noncancerous areas, epithelial cells demonstrated equally strong membranous expression of E-cadherin and β-catenin localised to the cell-cell junctions. Reduced expression of E-cadherin and β-catenin was demonstrated in 75% and 81.8% of the colorectal carcinoma cases, respectively. The down-regulation of both E-cadherin and β-catenin was correlated with decreased differentiation and increased tumour grade. In addition, the expression of β-catenin was correlated with tumour size. These results suggest that dysfunction of the E-cadherin-catenin complex starts in the early stages of carcinogenesis and that the disruption of the tissue architecture is progressively associated with the invasion of the tumour.