Kringle 1–4 of Hepatocyte Growth Factor Inhibits Proliferation and Migration of Human Microvascular Endothelial Cells

Abstract

NK4 composed of the N-terminal hairpin and subsequent four-kringle domains of Hepatocyte growth factor (HGF) is bifunctional, acting as a competitive antagonist for HGF and an angiogenesis inhibitor. In this study, we determined whether or not four-kringle domains of HGF (K1–4) have anti-angiogenic activity. For this purpose, we prepared recombinant K1–4 and NK4, using the baculovirus expression system. Although NK4 antagonized HGF-induced DNA synthesis of rat hepatocytes, cell scattering of MDCK cells and the c-Met/HGF receptor tyrosine phosphorylation in endothelial cells, K1–4 failed to antagonize HGF-induced DNA synthesis, cell scattering and the c-Met/HGF receptor tyrosine phosphorylation in endothelial cells, thus, indicating that K1–4 lacks HGF-antagonist activity. However, endothelial proliferation and migration induced by HGF was inhibited by K1–4, similar to the case seen with NK4. Furthermore, K1–4 inhibited the proliferation and migration of human dermal microvascular endothelial cells induced by vascular endothelial growth factor or by basic fibroblast growth factor. We propose that kringle 1–4 of HGF inhibits angiogenic responses in endothelial cells, independently of HGF-c-Met signaling pathways.