Study Of Endostatin And Its Mimic-peptides In Inhibiting Angiogenesis

Endostatin, a 20-kDa proteolytic fragment of collagen XVIII, is a potent inhibitor of angiogenesis and tumor growth. The anti-angiogenic effects of endostatin include inhibition of endothelial cell migration and proliferation, and inhibition of the activity of MMP2. Structure–function analysis of endostatin that implies this contravention function buried in separate fragments of endostatin introduces new issues into the understanding of the structure–function relationship of endostatin. We developed and characterized a novel murine McAb 4E7, against human endostatin, which antagonizes the function of endostatin. As we showed here, McAb 4E7 blocked the anti-migration/adhesion effects of endostatin in vitro and the anti-angiogenesis effect in vivo. So, the anti-proliferation and anti-migration function of endostatin may be related with distinct structural bases. Endostatin was discovered as a potent inhibitor of angiogenesis. Systematic administration of recombinant endostatin resulted in regression of various tumors in an xenograft model without any development of resistance. On the cellular level, endostatin was shown to inhibit endothelial cell proliferation and migration, and to induce endothelial cell apoptosis. But the phase I and II clinical trial of recombinant endostatin showed that its significant anti-cancer effect was exhibited only in a few patients with tumors. Meanwhile, Structure–function analysis of endostatin implies that the contravention function buried in different fragments of endostatin. The next step we used this novel monoclonal antibody to biopan the phage displayed random 15 peptides library and got a conservative sequence, which mimic the bioactivity of endostatin. This endo-mimic peptide was ready for design and synthesis of small molecular chemical drugs. Despite its potent antiangiogenic activity in vivo and in vitro, the molecular mechanisms of endostatin-mediated anti-angiogenesis and tumor regression have not been clear as yet. We selected the mice cornea as an animal model of angiogenesis. Corneal neovascularization is a sight-threatening complication of corneal infections, chemical injury and keratoplasty. It may become clinical useful for a variety of ocular diseases involving in neovascularization which is still pharmacologically untreatable. In order to understand the mechanism of endostatin in corneal angiogenesis, we measured the changes of VEGF and MMPs, which were important in the corneal wound healing and angiogenesis, by real time PCR and immunohistochemistry. Topical application of endostatin led to a significant reduction of alkaline-burn-induced corneal neovascularization. VEGF, MMP-2 and MMP-9 mRNA and protein content in cornea were increased by endostatin treatment. Endostatin can significantly inhibit the corneal neovascularization, meanwhile, endostatin delay the corneal wound healing induced by alkaline burn. These findings in the current study provide the first evidence that some undesirable effects on corneal wound healing from the use of endostatin as an anti-angiogenesis drug may be secondary to the over-expression of the metalloproteinases.