MAGIC-FACTOR, A PARTIAL AGONIST OF MET, ACTS AS A SAFE HEPATOTROPHIC CYTOKINE

Background and Aims: Hepatocyte growth factor (HGF) is the most powerful hepatotropic cytokine. However the ability of HGF to promote tumor cell “scattering” and “invasion” raises some concern about its therapeutic safety. We have already reported that Metron factor-1, an engineered cytokine derived from HGF and macrophage stimulating protein, is as effective as HGF at preventing liver injury and at promoting hepatocyte regeneration, but therapeutically safer than HGF (Hepatology, 2008). Here we report the newly engineered agonist of Met, MAGIC factor (Met-Activating Genetically Improved Chimeric Factor) that contains two Met-binding domains repeated in tandem, and tried to elucidate its biological function in the liver. Methods: CHO cells were transduced MAGIC factor, and the medium was purified through chelate column to obtain MAGIC factor. For in vitro study we used mouse hepatocytes, human HCC cell lines (HepG2, Huh-1) and human umbilical vessel epithelial cells (HUVECs). Signaling pathway of AKT and ERK, and cell cycle-related protein, Cyclin D1 and CDK4, were examined by Western Blot. Mitogenic and apoptotic activity was determined by BrdU incorporation and cell death detection kit, respectively. Cell migration and invasion activity were examined through transwell chambers. ECM remodeling of HUVECs was determined by the length of pseudopodia. Results: MAGIC stimulation as well as HGF caused increased expression of phospho-AKT and phospho-ERK, Cyclin D1,and CDK-4 in hepatocytes. BrdU incorporation was increased by MAGIC factor at 2.0 folds, almost as much as HGF. Fas-mediated apoptosis in hepatocytes was protected by 80% by HGF, and 70% by MAGIC. Matrigel invasion assay of HCC cells and migration assay of HUVECs showed the increased cells at 2.2 folds and 2.5 folds by HGF respectively, by but not by MAGIC factor. Tube length of HUVECs was also stimulated at 2.4 folds by HGF, but not by MAGIC factor. Conclusions: MAGIC factor has mitogenic and anti-apoptotic ability on hepatocytes but lacks proangiogenic and invasive activity. MAGIC factor may act as a safe hepatotropic cytokine.