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

血管抑素(AG)是纤溶酶原(PL)等具有克林格尔结构的凝血因子被裂解的产物。据报道，银杏叶提取物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的作用机制和临床应用。在所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。人巨噬细胞金属酯酶是裂解酶的候选酶之一，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，并加入纯化的AG。从人血浆中提纯PL，然后用弹性酶切割，再进行纯化。采用胶原酶灌流和Percoll离心法纯化大鼠肝内皮细胞。AG抑制内皮细胞生长，其作用依赖于bFGF途径。在另一项研究中，通过Western blotting判断，30%的肝细胞癌患者的血浆中有AG。我们尝试对肝癌细胞系进行免疫染色，发现HepG2细胞可能表达ATP合成酶，该酶已被报道为AG的表面受体。我们将利用该细胞检测AG可以抑制恶性表型转变，如钙粘附素E向N型的转变。

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.