Immunohistochemical study of the canonical and non-canonical Wnt signaling pathway in colorectal carcinoma and non-neoplastic mucosa^*

Estudo imunoistoquímico da via de sinalização canônica e não canônica da proteína Wnt em carcinoma colorretal e em mucosa não neoplásica

ABSTRACT

Colorectal cancer is linked to several signaling pathways such as Wnt pathway. Our objective is to detect and verify the integrity of protein members of Wnt signaling pathway in colorectal carcinoma and non-neoplastic colorectal tissue. Sixty-four patients with colorectal carcinoma provided samples of colorectal neoplasia and non-neoplastic tissues, which were prepared in tissue microarray blocks and subjected to immunohistochemical analysis. The primary antibodies used were Wnt-1, Wnt-2, Wnt-5a Frizzled-1, Frizzled-5 and axin. Immunoexpression of Wnt-2 protein was significantly lower in colorectal tumor tissue and axin protein immunoexpression was significantly higher in tumor tissue. There was no significant difference in the expression of Wnt-1, Wnt-5a, Frizzled-1 and Frizzled-5 proteins in both tissues. The higher expression of Wnt-2 protein in non-neoplastic colorectal tis- sue suggests the participation during the hyperproliferative stage of colorectal mucosa. The increased axin protein immunoexpression in colorectal tumor suggests a decrease in the formation of the β-catenin destructor complex.

Keywords:
Colorectal neoplasms; Wnt proteins; Frizzled receptors; Axin signaling complex; Immunohistochemistry