Sheu J R, Lin C H, Peng H C, Huang T F
Pharmacological Institute, College of Medicine, National Taiwan University, Taipei.
Peptides. 1994;15(8):1391-8. doi: 10.1016/0196-9781(94)90114-7.
Triflavin, a 7.5-kDa cysteine-rich polypeptide purified from Trimeresurus flavoviridis snake venom, belongs to a family of RGD-containing peptides, termed disintegrins, that have been isolated from the venoms of various vipers and shown to be potent inhibitors of platelet aggregation. The interaction of tumor cells with extracellular matrices such as fibronectin, vitronectin, and collagen has been shown to be mediated through a family of cell surface receptors that specifically recognize an arginine-glycine-aspartic acid (RGD) sequence within each adhesive protein. In this study, we show that triflavin dose-dependently inhibited adhesion of human cervical carcinoma (HeLa) cells to extracellular matrices (ECMs; i.e., fibronectin, fibrinogen, and vitronectin). On the other hand, triflavin exerted a limited inhibitory effect on cell adhesion to laminin and collagen (type I and IV). On a molar basis, triflavin is approximately 800 times more potent than Gly-Arg-Gly-Asp-Ser (GRGDS) at inhibiting cell adhesion. When immobilized on plate, triflavin significantly promoted HeLa cell adhesion, and this attachment was inhibited by GRGDS. Furthermore, FITC-conjugated triflavin bound to cells in a saturable manner and its binding was inhibited by GRGDS. In addition, triflavin did not affect [3H]thymidine uptake of HeLa cells during a 3-day incubation. These results suggest that triflavin probably binds to integrin receptors expressed on HeLa cell surface via its RGD sequence within its molecule, thereby inhibiting the adhesion of extracellular matrices to HeLa cells.
竹叶青毒素是一种从竹叶青蛇毒中纯化得到的7.5 kDa富含半胱氨酸的多肽，属于含RGD的肽家族，即去整合素，这类物质已从多种蝰蛇毒液中分离出来，并被证明是血小板聚集的有效抑制剂。肿瘤细胞与细胞外基质（如纤连蛋白、玻连蛋白和胶原蛋白）的相互作用已被证明是通过一类细胞表面受体介导的，这类受体能特异性识别每种黏附蛋白中的精氨酸-甘氨酸-天冬氨酸（RGD）序列。在本研究中，我们发现竹叶青毒素能剂量依赖性地抑制人宫颈癌（HeLa）细胞与细胞外基质（ECM；即纤连蛋白、纤维蛋白原和玻连蛋白）的黏附。另一方面，竹叶青毒素对细胞与层粘连蛋白和胶原蛋白（I型和IV型）的黏附具有有限的抑制作用。以摩尔计，竹叶青毒素在抑制细胞黏附方面的效力比甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸（GRGDS）强约800倍。当固定在平板上时，竹叶青毒素能显著促进HeLa细胞黏附，而这种黏附可被GRGDS抑制。此外，异硫氰酸荧光素（FITC）标记的竹叶青毒素以饱和方式与细胞结合，其结合可被GRGDS抑制。此外，在3天的孵育过程中，竹叶青毒素不影响HeLa细胞的[3H]胸腺嘧啶核苷摄取。这些结果表明，竹叶青毒素可能通过其分子内的RGD序列与HeLa细胞表面表达的整合素受体结合，从而抑制细胞外基质与HeLa细胞的黏附。
