Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium.
Mol Cancer Ther. 2012 Apr;11(4):817-29. doi: 10.1158/1535-7163.MCT-11-0738. Epub 2012 Feb 1.
5'-O-Tritylinosine (KIN59) is an allosteric inhibitor of the angiogenic enzyme thymidine phosphorylase. Previous observations showed the capacity of KIN59 to abrogate thymidine phosphorylase-induced as well as developmental angiogenesis in the chicken chorioallantoic membrane (CAM) assay. Here, we show that KIN59 also inhibits the angiogenic response triggered by fibroblast growth factor-2 (FGF2) but not by VEGF in the CAM assay. Immunohistochemical and reverse transcriptase PCR analyses revealed that the expression of laminin, the major proteoglycan of the basement membrane of blood vessels, is downregulated by KIN59 administration in control as well as in thymidine phosphorylase- or FGF2-treated CAMs, but not in CAMs treated with VEGF. Also, KIN59 abrogated FGF2-induced endothelial cell proliferation, FGF receptor activation, and Akt signaling in vitro with no effect on VEGF-stimulated biologic responses. Accordingly, KIN59 inhibited the binding of FGF2 to FGF receptor-1 (FGFR1), thus preventing the formation of productive heparan sulphate proteoglycan/FGF2/FGFR1 ternary complexes, without affecting heparin interaction. In keeping with these observations, systemic administration of KIN59 inhibited the growth and neovascularization of subcutaneous tumors induced by FGF2-transformed endothelial cells injected in immunodeficient nude mice. Taken together, the data indicate that the thymidine phosphorylase inhibitor KIN59 is endowed with a significant FGF2 antagonist activity, thus representing a promising lead compound for the design of multitargeted antiangiogenic cancer drugs.
5'-O-三苯甲基肌苷（KIN59）是血管生成酶胸苷磷酸化酶的别构抑制剂。先前的观察结果表明，KIN59 能够消除胸苷磷酸化酶诱导的以及在鸡绒毛尿囊膜（CAM）试验中的发育性血管生成。在这里，我们表明 KIN59 还抑制了由成纤维细胞生长因子-2（FGF2）触发的血管生成反应，但在 CAM 试验中不抑制血管内皮生长因子（VEGF）。免疫组织化学和逆转录 PCR 分析表明，在对照以及胸苷磷酸化酶或 FGF2 处理的 CAM 中，KIN59 给药下调了血管基底膜的主要糖胺聚糖层粘连蛋白的表达，但在 VEGF 处理的 CAM 中则没有。此外，KIN59 在体外消除了 FGF2 诱导的内皮细胞增殖、FGF 受体激活和 Akt 信号转导，而对 VEGF 刺激的生物学反应没有影响。因此，KIN59 抑制了 FGF2 与 FGFR1（FGFR1）的结合，从而防止了有功能的硫酸乙酰肝素蛋白聚糖/FGF2/FGFR1 三元复合物的形成，而不影响肝素的相互作用。与这些观察结果一致，KIN59 的全身给药抑制了 FGF2 转化的内皮细胞注射到免疫缺陷裸鼠中诱导的皮下肿瘤的生长和新生血管形成。总之，这些数据表明，胸苷磷酸化酶抑制剂 KIN59 具有显著的 FGF2 拮抗剂活性，因此代表了设计多靶向抗血管生成癌症药物的有前途的先导化合物。
