基于2-（取代三唑基）吡啶结构的选择性Raf激酶抑制剂的分子构建和抗肿瘤活性评价

Raf which belongs to serine/threonine protein family, plays an important role in the Ras/Raf/MEK/ERK signaling cascade, and is critical to the survival, growth and proliferation of cells. Overexpression or mutation of Raf kinase is found in several tumor types, and has become an attractive target in cancer therapy. Sorafenib is a multikinase inhibitor against Raf, VEGFR and PDGFR, it demonstrates outstanding inhibitions across a broad spectrum of tumor types and is widely used in clinic. However, its unsatisfactory bioavailability and adverse effects which are accompanied with the poor water-solubility and kinase selectivity limit the application to some extent. In our previous study, we have reported a series of 2-(4-(2-(dimethylamino)ethyl)-4H-1,2,4-triazol-3-yl)pyridine analogs, which demonstrated better antitumor potency than sorafenib in several cancer cells. Also, they possessed favorable kinase selectivity and water-solubility. In this research, we serve 2-triazolyl pyridine as a privileged fragment for the hinge-region binder, major efforts will focus on the optimization at 4-position, which is close to a protein groove. We will synthesize a series of novel compounds, and their biological activities will be evaluated. Through the research, we hope to further investigate the SARs of this series of compounds, and to discover selective Raf kinase inhibitors, which possess good activity, safety as well as pharmacokinetic properties.

Raf激酶是一种重要的丝/苏氨酸蛋白激酶，在Ras/Raf/MEK/ERK信号传导通路中发挥着重要作用，其过表达或突变会导致细胞的过度增殖，已被确认为肿瘤治疗的重要靶标。上市药物sorafenib具有广谱的抗肿瘤活性，但由于其分子水溶性小、激酶选择性差，在一定程度上导致了药物吸收较差、副作用较多，限制了其临床应用。前期研究中，课题组发现以2-（4-（二甲氨基乙基）-4H-1,2,4-三唑-3-基）吡啶为铰链区结合位点的衍生物对肿瘤细胞的增殖抑制作用明显优于sorafenib，并且具有良好的Raf激酶选择性和水溶性。在此基础上，本课题拟将2-三唑基吡啶作为铰链区结合位点的骨架结构开展深入的优化设计，重点在毗邻蛋白空腔的三唑环4位引入水溶性的侧基，寻找更佳的铰链区结合位点结构，并进一步修饰从而获得具有良好生物活性、成药性的选择性Raf激酶抑制剂，并为后续的创新药物研究奠定基础。

多靶点抑制剂sorafenib具有突出的、广谱的抗肿瘤作用，然而其药物吸收差、毒副作用明显的弊端在一定程度上限制了其应用。因此，针对其缺陷，开发更加安全有效的多靶点抑制剂具有重要意义。本项目在前期研究基础上，系统分析总结了sorafenib的构效关系，认为其结构应包含四个关键的结构区，依次为HRB区（铰链区结合位点）、“Linker”、HBR区（氢键结合区）以及HM区（疏水片段）。针对每个功能片段的结构特征，结合计算机辅助药物设计技术，课题组开展了大量的结构设计、合成工作。同时，课题组设计了多种实验模型来深入探讨化合物生物活性以及作用机制。通过化合物设计、合成、活性筛选、再设计合成、机制探讨的药物研发过程，课题组发现了多个具有进一步开发前景的化合物。当在2-三唑基吡啶结构中引入二乙氨基乙基时，化合物13i对c-Kit、Ret、Flt3激酶都具有显著的抑制活性，同时能有效抑制多种肿瘤细胞增殖，诱导HT-29细胞凋亡。当以1,2,3-三唑或双缩脲替换sorafenib的脲结构时，化合物仍具有显著的抗肿瘤活性。其中化合物8f有效抑制HT-29、MCF-7细胞增殖、抑制HT-29细胞克隆形成，并诱导其发生凋亡。4c和4h不仅具有高水平生物活性，在体外人肝微粒体共培育测试中表现出极高的稳定性。通过系统的结构修饰工作，我们初步明确了2-三唑基吡啶类化合物的构效关系，为进一步开发有效的抗肿瘤药物奠定了基础。