Characterization, expression and function of c-Met in canine spontaneous cancers

Aberrant expression of the proto-oncogene c-Met has been noted in a variety of human cancers. To better define the potential role of Met dysregulation in canine cancer, the canine Met, hepatocyte growth factor (HGF) and HGF activator were cloned. Inappropriate expression of Met was present in canine tumour cell lines derived from a wide variety of cancers. Furthermore, both HGF and HGF activator were also expressed in several of these cell lines, providing evidence of a possible autocrine loop of Met activation. Stimulation of tumour cell lines with recombinant human HGF induced Met autophosphorylation, as well as activation of the downstream signalling elements Gab-1, Akt and Erk1/2. Scattering of tumour cells and migration across a defect occurred in response to HGF stimulation. The Met inhibitor PHA665752 blocked both HGF-induced phosphorylation of canine Met and HGF-mediated cell cycling, scattering and migration. These studies provide evidence that Met dysregulation may play a role in the biology of canine cancer and lay the groundwork for future studies employing Met inhibitors.