The study of tumor vessel growth inhibiton Angiostatin, new mechanism of action and clinical application

血管抑制素（Angiostatin， AG）是一种具有褶皱结构的凝血因子，如纤溶酶原（Plasminogen， PL）被裂解的产物。据报道，AG在体内具有抑制癌细胞生长的能力。在本研究中，我们探讨了AG的机制和临床应用。在检测的人肝癌细胞系中，只有Huh-7细胞能够裂解纯化的PL，并产生AG。巨噬细胞金属酯酶是一种候选的切割酶，在所有细胞系中都有表达。接下来，我们使用原代肝内皮细胞培养并添加纯化AG。从人血浆中纯化PL，然后用弹性酶裂解，再纯化。采用胶原酶灌注和percoll离心纯化大鼠肝内皮细胞。AG对内皮细胞生长的抑制作用依赖于bFGF通路。在另一项研究中，30%的肝细胞癌患者经Western blotting检测血浆中存在AG。我们对肝癌细胞系进行免疫染色，发现HepG2细胞可能表达ATP合酶，而ATP合酶曾被报道为AG的表面受体。我们将研究AG可以抑制恶性表型变化，如钙粘蛋白E到N型，使用这种细胞。

Angiostatin (AG) is a product of which a coagulation factor with klingle structure, such as Plasminogen(PL) is cleaved. AG was reported to have capacity to inhibit the growth of cancer cells in vivo. In this study, we examine the mechanism and clinical application of AG. Among the human liver cancer cell lines examined, only Huh-7 cells can cleave purified PL, and produce AG. Human macrophage metalloesterase, a candidate of the cleaving enzyme, is expressed in all cell lines. We next used primary liver endothelial cell culture and add purified AG. From human plasma, PL was purified and then cleaved by elastase, and purified again. Rat liver endothelial cells were purified by collagenase perfusion and percoll centrifugation. AG inhibited endothelial cells growth and the effect depended on bFGF pathway. In another study, 30% of the patients of hepatocellular carcinoma had AG in their plasma judging by Western blotting. We tried immunological staining of liver cancer cell lines and found that HepG2 cells may express ATP synthase, which had been reported as a surface receptor of AG. We will examine that AG could inhibit malignant phenotypical change, such as cadherin E to N type, using this cells.