Invasion in colorectal liver metastases

The death receptor CD95 does not only signal apoptosis but is also able to signal invasion in colorectal liver metastasis formation through activation of the cofilin pathway. It seems that in a subset of colorectal tumors the invasion signal of CD95 is mediated through the tyrosine kinase receptor PDGF. PDGF is expressed by epithelial colorectal cancer cells when transitioned to a more migration prone mesenchymal phenotype. Stimulation of the PDGF receptor on colorectal tumor cells which underwent epithelial to mesenchymal transition enhances the efficiency of liver metastasis formation. With the development of a new intravital imaging window it was shown that migration and invasion is a rate limiting step in the initial, single cell, phase of colorectal liver metastases formation. This stage was termed the pre-micrometastasis stage. The newly developed intravital abdominal imaging window can be utilized for the observation of liver metastasis formation and many other physiological and pathological processes in the, until now, black box of the abdomen.