Expression of Wnt pathway components frizzled and disheveled in colon cancer arising in patients with inflammatory bowel disease

Abstract

Mutations in apc which lead to activation of the Wnt signaling pathway are a hallmark of sporadic colon cancers but occur infrequently in colon cancers arising in patients with inflammatory bowel disease (IBD). There is evidence, however, that other components of the Wnt pathway may be altered in IBD-related colon cancer. In this study, we examined the expression the Wnt pathway components frizzled (Fz), the cell surface receptor, and disheveled (DVL), a family of cytoplasmic signal transduction molecules, in IBD and IBD-related colon cancer. Paraffin sections of normal and malignant colon tissues were obtained from patients with a history of ulcerative colitis and from controls with sporadic colon cancer. Tissue sections were stained with antibodies directed against Fz1/2 receptors and DVL1, DVL2 and DVL3 and antigen expression visualized by immunohistochemistry. Fz1/2 receptors were minimally expressed in normal IBD mucosa, were not expressed in IBD colon cancer, but exhibited strong expression in dysplastic tissues adjacent to the cancers. DVL1 was not expressed in IBD normal mucosa or normal mucosa from non-IBD patients, but was expressed in all cancers. DVL2 and DVL3 were expressed in all normal mucosa samples tested, and in sporadic colon cancer, but were not expressed in colon cancers arising in IBD patients. The characteristics of Fz and DVL expression in IBD tissues reported herein provides evidence of the importance of Wnt signaling in IBD and IBD-related colon cancer and, specifically, the significance of non-APC components of this pathway. Fz may serve as a marker for dyspasia in IBD patients and DVL1 is a potential therapeutic target for IBD-related colon cancer.