SUV39H2和G9a选择性可转换抑制剂的设计与合成

Design and synthesis of chemical probes targeting histone modification enzymes can help people to understand how "histone code" regulates the biochemical process such as transcriptional activation or repression and DNA repair and the development of diseases such as cancer, neuropathy and immunodeficiency. Based on the discovry of chemical probes,the new drugs targeting these enzymes could be developed. Considering H3K9 methyltransferases SUV39H2 and G9a with structural related SET domain, Application of the targeted design strategy to create selectivity switchable small molecule inhibitors or probes and the following research such as anti-tumor test is our proposal. According to the preliminary test results, we found two structural different small molecules which both inhibit SUV39H2 and G9a with a little selectivity. One is peptide substrate competitive inhibitor and the other one is cofactor SAM competitive inhibitor. Furthermore, The docking models of SUV39H2/G9a and the small molecules confirmed our hypothesis that it could be plausible to switch the selectivity between SUV39H2 and G9a via structural modifications of the inhibitors. By using combinatorial chemistry strategy, we will optimize the hits via iterative design, synthesis and assessment in biochemical or cellular assays to create SUV39H2 and G9a chemical probes with well defined pharmacological profiles.

设计和合成以组蛋白修饰酶为靶点的化学探针，可以帮助人们深入了解"组蛋白密码"如何激活或抑制基因转录、DNA修复等生化过程以及如何影响肿瘤、神经疾病、免疫缺陷等相关疾病的形成和发展，从而进一步研发出以这些酶为靶点的新药。本项目拟以SET 结构域相近的组蛋白H3K9甲基化转移酶SUV39H2和G9a为靶点，设计并合成选择性可转换小分子抑制剂或探针,然后开展抗肿瘤活性等相关研究。通过前期的活性测试结果，我们发现有两类结构迥异的小分子均能抑制SUV39H2和G9a的活性，并且有一定的选择性；其中一类是与底物竞争的抑制剂，另一类是与辅因子SAM竞争的抑制剂。小分子和蛋白质之间相互作用的计算模拟结果显示，通过对抑制剂结构上的改造可以达到对SUV39H2和G9a抑制选择性的转换。我们将以组合化学为手段，设计和合成小分子化合物，然后根据其构效关系，进一步优化和发展出SUV39H2和G9a小分子探针。

以组蛋白H3K9甲基化转移酶SUV39H2和G9a为靶点，基于高通量筛选发现的两个结构迥异的先导化合物，即含有8-羟基喹啉骨架和喹唑啉母核的小分子，进行结构改造和优化，以期提高小分子的活性和选择性。结合虚拟对接模型，采用组合化学的合成策略，从商品化的原料出发，通过几步经典的反应即可得到一系列类似物，然后采用Thioglo-based Assay方法对小分子进行酶活性筛选，发现一系列8-羟基喹啉类化合物能很好的抑制SUV39H2的活性，酶动力学竞争实验表明，这些小分子是与辅因子SAM竞争的抑制剂，尽管这一类化合物在酸性条件下不太稳定；而基于喹唑啉母核的一系列化合物，对SUV39H2均没有明显的抑制活性。整合G9a小分子抑制剂的药效团（喹唑啉骨架）作为HDAC抑制剂的封端基团；基于此，设计和合成了一些G9a/HDACs小分子双抑制剂，然后进行了初步的体外抗恶性血液病研究，发现这些化合物对多种恶性血液病细胞株均有剂量依赖抑制效果。本项目的研究成果及所设计和合成的小分子抑制剂对深入了解那些与H3K9甲基化相关疾病的形成发展机制及进一步研发治疗药物有着重要的意义。