Soeda S, Kozako T, Iwata K, Shimeno H
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, 814-0180, Fukuoka, Japan.
Biochim Biophys Acta. 2000 Jun 2;1497(1):127-34. doi: 10.1016/s0167-4889(00)00052-5.
We have previously demonstrated that chemically oversulfated fucoidan (OSF) but not native fucoidan (NF) effectively suppresses the tube structure formation by human umbilical vein endothelial cells (HUVEC) on the basement membrane preparation, Matrigel. In this study, using more defined systems where basic fibroblast growth factor (bFGF) induces the tube formation by HUVEC on collagen gel, we investigated the mechanism responsible for the inhibition of angiogenesis by OSF in vitro. Unlike NF and desulfated fucoidan (desF), OSF potently inhibited the bFGF-induced HUVEC migration and tube formation. ELISA for tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) in the culture media indicated that OSF increased the bFGF-induced release of PAI-1 antigen, but not of t-PA antigen. Analyses of the binding of bFGF to HUVEC surfaces and the following protein tyrosine phosphorylation revealed that OSF could promote the cell binding and autophosphorylation of 140 and 160 kDa receptors. In heparitinase-treated HUVEC, contrarily, the bFGF binding and PAI-1 release were decreased by OSF. These results suggest that OSF is a highly sulfated unique polysaccharide that can promote the binding of bFGF to the heparan sulfate molecules required for binding to the high affinity receptors with tyrosine kinase activity. The resultant increase in PAI-1 release may play a key role for the prevention of cell migration accompanied by matrix proteolysis.
我们之前已经证明，化学过硫酸化岩藻依聚糖（OSF）而非天然岩藻依聚糖（NF）能有效抑制人脐静脉内皮细胞（HUVEC）在基底膜制剂基质胶上形成管状结构。在本研究中，我们使用更明确的系统，即碱性成纤维细胞生长因子（bFGF）诱导HUVEC在胶原凝胶上形成管状结构，来研究体外OSF抑制血管生成的机制。与NF和去硫酸化岩藻依聚糖（desF）不同，OSF能有效抑制bFGF诱导的HUVEC迁移和管状结构形成。对培养基中组织型纤溶酶原激活物（t-PA）和纤溶酶原激活物抑制剂-1（PAI-1）进行酶联免疫吸附测定（ELISA）表明，OSF增加了bFGF诱导的PAI-1抗原释放，但未增加t-PA抗原释放。对bFGF与HUVEC表面结合以及随后的蛋白酪氨酸磷酸化进行分析发现，OSF可促进140和160 kDa受体的细胞结合和自身磷酸化。相反，在经肝素酶处理的HUVEC中，OSF可降低bFGF结合和PAI-1释放。这些结果表明，OSF是一种高度硫酸化的独特多糖，可促进bFGF与硫酸乙酰肝素分子结合，而硫酸乙酰肝素分子是与具有酪氨酸激酶活性的高亲和力受体结合所必需的。由此导致的PAI-1释放增加可能在预防伴随基质蛋白水解的细胞迁移中起关键作用。
