Level of alpha-catenin expression in colorectal cancer correlates with invasiveness, metastatic potential, and survival.

Decreased expression of the E-cadherin/alpha-catenin cell-cell adhesion complex is considered to elicit detachment of tumor cells from primary lesions and development of metastases. The immunohistochemical profile of alpha-catenin in colorectal cancer, as well as its correlation with differentiation, lymph node/liver metastasis and patient survival is presented in this study. Alpha-Catenin expression was investigated with immunohistochemistry technique, in 85 paraffin-embedded and 21 fresh frozen specimens, including 82 colon adenocarcinomas, 10 adenomas, 10 lymph nodes, and 3 liver metastases. Preserved alpha-catenin expression was considered for those tumors that demonstrated more than 90% alpha-catenin(+) cancer cells and reduced alpha-catenin expression for those tumors with less than 90% alpha-catenin(+) cancer cells. The chi2-test was used to calculate the statistical correlation of alpha-catenin expression with grade of differentiation and metastatic potential and the log-rank test for the correlation with survival rate. Normal mucosa, as well as 8/10 of the colon adenomas, showed strong membranous alpha-catenin expression. Reduced alpha-catenin expression was found in 32/82 (39%) colorectal cancers examined, which was associated with de-differentiation (P < 0.01), lymph node metastasis (P < 0.025), and poor clinical outcome (P < 0.012). Alpha-Catenin expression was preserved in 3 liver metastases and their corresponding primary tumors. By contrast, 6/10 of lymphogenous metastases showed decreased alpha-catenin expression. Our findings demonstrate a significant down-regulation of alpha-catenin expression in colorectal cancer which is associated with poor differentiation, higher metastatic potential and unfavorable prognosis. These preliminary results suggest that alpha-catenin may be a useful marker of invasiveness, metastatic potential, and survival in colorectal cancer patients.