Open Access
Wnt/FZD signaling and colorectal cancer morphogenesis
Falk Hlubek1,Simone Spaderna1,Otto Schmalhofer1,Andreas Jung1,Thomas Kirchner1,Thomas Brabletz1
Department of Pathology, University of Erlangen-Nürnberg, Krankenhausstr. 8-10, 91054 Erlangen, Germany
DOI: 10.2741/2075 Volume 12 Issue 2, pp.458-470
Published: 01 January 2007
(This article belongs to the Special Issue WntFZD signalling in cancer and disease)

Malignant progression of colorectal carcinomas is characterized by an epithelial-mesenchymal transition (EMT)-like de-differentiation of the invading tumor cells. However a re-differentiation towards an epithelial phenotype, resembling a mesenchymal-epithelial transition (MET), is detectable in metastases. This indicates that malignant progression is based on dynamic processes, which can not be explained solely by irreversible genetic alterations, but must be additionally regulated by the tumor environment. The main oncoprotein in colorectal cancer is the Wnt-pathway effector beta-catenin, which in most cases is overexpressed due to mutations in the adenomatous polyposis coli (APC) tumor suppressor. EMT of tumor cells is associated with a nuclear accumulation of the transcriptional activator beta-catenin, which is reversed in metastases. Nuclear beta-catenin is involved in two fundamental processes in embryonic development: EMT and stem cell formation. Accumulating data demonstrate that aberrant nuclear expression of beta-catenin can also confer these two abilities to tumor cells, indicating the crucial role of aberrant Wnt-signaling for malignant tumor progression.

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Falk Hlubek, Simone Spaderna, Otto Schmalhofer, Andreas Jung, Thomas Kirchner, Thomas Brabletz. Wnt/FZD signaling and colorectal cancer morphogenesis. Frontiers in Bioscience-Landmark. 2007. 12(2); 458-470.