Substrate competitive inhibitors of IGF-1 receptor kinase
Substrate competitive inhibitors of IGF-1 receptor kinase
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DOI：
10.1021/bi001516y
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发表时间：
2000-12-26
期刊：
影响因子：
2.9
通讯作者：
Levitzki, A
中科院分区：
文献类型：
--
作者：
Blum, G;Gazit, A;Levitzki, A
IGF-1及其受体在许多癌症中起着关键作用，因此，IGF-1R是设计抑制剂的有吸引力的靶标。在这篇文章中，我们报告了一些分离的IGF-1R激酶抑制剂的先导化合物。这些化合物的搜索利用了两种新的体外试验，并通过胰岛素受体激酶结构域的三维结构的知识，这是84%同源的IGF-1R激酶结构域的帮助。在这些试验中发现的最有效的抑制剂是酪氨酸磷酸化抑制剂AG 538，IC 50 = 400 nM。在计算机建模中，AG 538被置于胰岛素受体的激酶结构域中，并且能够取代酪氨酸1158和1162，其经历自磷酸化。实验上确实发现AG 538不与ATP竞争，但与IGF-1R底物竞争。我们制备了I-OMe AG 538，其比AG 538更疏水且对氧化更不敏感。AG 538和I-OMe AG 538均以剂量依赖性方式抑制完整细胞中的IGR-1R自磷酸化，但I-OMe-AG 538更优，可能是因为其增强的疏水性质。两种化合物均抑制下游靶点PKB和Erk2的活化。这些结果表明AG 538和I-OMe-AG 538可作为开发IGF-IR底物竞争性抑制剂的先导化合物，并讨论了底物竞争性抑制剂相对于ATP竞争性抑制剂的可能优势。
IGF-1 and its receptor play a pivotal role in many cancers, and therefore, IGF-1R is an attractive target for the design of inhibitors. In this communication, we report on a number of lead compounds for inhibitors of the isolated IGF-1R kinase. The search for these compounds utilized two novel in vitro assays and was aided by the knowledge of the three-dimensional structure of the insulin receptor kinase domain, which is 84% homologous to the IGF-1R kinase domain. The most potent inhibitor found in these assays was tyrphostin AG 538, with an IC50 = 400 nM. In computer modeling, AG 538 was placed in the kinase domain of the insulin receptor and was able to sit in place of tyrosines 1158 and 1162, which undergo autophosphorylation. Experimentally it is indeed found that AG 538 does not compete with ATP but competes with the IGF-1R substrate. We prepared I-OMe AG 538, which is more hydrophobic and less sensitive to oxidation than AG 538. Both AG 538 and I-OMe AG 538 inhibit IGR-1R autophosphorylation in intact cells in a dose-dependent manner but I-OMe-AG 538 is superior, probably because of its enhanced hydrophobic nature. Both compounds inhibit the activation of the downstream targets PKB and Erk2. These findings suggest that AG 538 and I-OMe-AG 538 can serve as a lead compound for the development of substrate competitive inhibitors of the IGF-IR. The possible advantage of substrate competitive inhibitors vis-g-vis ATP competitive inhibitors is discussed.