The Development of HGF Mimetics Using Human Antibodies with Agonist Effect Against c-Met

Abstract

Human Hepatocyte Growth Factor (HGF) is known to play important roles in various tissues such as the liver, lung, kidney, and nervous system. HGF binds to its receptor c-Met, and activates a signal cascade that leads to proliferation, differentiation, motility, and survival of the cell. As such, the HGF/c-Met signaling system plays crucial roles in organogenesis during embryonic development and tissue regeneration. It was also observed that administration of human recombinant HGF on animal models with degenerative diseases leads to better prognosis. HGF is in its natural form fairly unstable, with serum levels dropping drastically several minutes after administration, making it difficult to use as a therapeutic molecule. To overcome these obstacles, we have identified and characterized antibodies A8 and A11 that bind to the HGF receptor, c-Met, with agonist properties that are able to induce the same signaling cascades. The identification of the antibody binding to c-Met was done by phage display screening and verified through ELISA and flow cytometry. The inducing of phosphorylation signals at catalytic and docking sites and the activation of Akt and Erk signals was seen when treated with A8 and A11 alone, indicating agonist properties of the antibodies. Proliferation was observed, proof that the induction of signals results in direct effect on the cells. We could also verify through adipose-derived mesenchymal stem cell culture that A8 and A11 could substitute the role of HGF in maintaining multipotency. We have thus verified c-Met agonist antibodies that hold the potential of being used as a substitute for HGF in mesenchymal stem cell culture for therapeutic purpose and possibly in treatments for chronic and degenerative diseases.