Study of APC and betha-catenin protein expression in polyps and colorectal adenocarcinoma

ABSTRACT

OBJECTIVE: To study part of the Wnt signaling pathway for carcinogenesis in colorectal cancer and polyps, through adenomatous polyposis coli (APC) and β-catenin protein expression. METHODS: We studied the immunoexpression of APC protein and β-catenin in the adenocarcinoma and polyps (adenoma) from ninety-one patients who underwent resection of sporadic colorectal cancer (CRC) with curative intent from 1993 to 2004 at the Hospital do Câncer de Barretos (Brazil). Each patient was resected within a period 3 months before or after diagnosis. The polyps or adenocarcinoma was considered positive for APC when more than 10% of the cells showed cytoplasmic staining and for β-catenin when more than 5% of the cells showed nuclear stainning. RESULTS: Among the 91 patients, we found association among APC protein expression in the polyps and in the respective colorectal adenocarcinoma (p = 0.014). Similarly, there were significant association with nuclear expressions (p = 0.001) of β-catenin in the polyps and colorectal adenocarcinoma. Nuclear β-catenin expression was associated with villous adenoma (86%, p = 0.042). There was no association among APC and β-catenin expression and any other histological finding. CONCLUSION: There is an association of APC and β-catenin protein expression in polyps and in colorectal adenocarcinoma. This finding allows us to speculate that in the same patient the same WNT pathway or another is activated in both lesions; polyp and adenocarcinoma. Villous adenomas occur most frequently via the Wnt signaling pathway.