基于 MDM2-p53 结构的新型小分子抑制剂 LJ1019 的结构优化及 抗肿瘤活性研究

p53 is a powerful tumor suppressor and is an attractive cancer therapeutic target because it can be functionally activated to eradicate tumors. The gene encoding p53 protein is mutated or deleted in half of human cancers, which inactivates its tumor suppressor activity. In the remaining cancers, p53 retains its wild-type form but its activity is effectively inhibited through direct interaction with the human murine double minute 2 (MDM2) oncoprotein. Blocking the MDM2-p53 interaction to reactivate the p53 function is a promising cancer therapeutic strategy. In our preliminary work, an integrated virtual database screening strategy, which combined both pharmacophore based and structure based (docking) method, and SPR were employed to identify compound LJ1019 as MDM2-p53 interaction inhibitor with novel scaffold. Additionally, LJ1019 showed antiproliferative activity against HCT116, A549 and MCF7 cell lines possessing wild-type p53 with IC50 values was comparable to that of reference drug natlin-3a. Based on those preliminary results, in this proposal, LJ1019 was chosen as the hits compound, and structure-based hits optimization was carried on based on its docking pose in the binding pocket of MDM2 by using scaffold hopping and privileged structures-oriented method,in order to discover promising lead compounds with potent antiproliferative activity and superior physicochemical and ADMET profiles, and pave the way for the development of novel anticancer drugs.

p53是迄今发现与人肿瘤发生相关性最高的抑癌基因。MDM2蛋白与p53结合抑制其功能，导致肿瘤发生及转移，设计阻断两者作用的小分子具有非常重要的意义。本课题前期以此为靶点，使用CCAD联合SPR的方法筛选化合物库，得到先导物LJ1019，未见此类结构被报道具有抗肿瘤活性，经免疫共沉淀实验验证机制，细胞实验IC50值与阳性对照nutlin-3a相当，体内实验有效。LJ1019结构新颖，靶点明确，抗肿瘤活性确切，结构改造空间大。本项目根据LJ1019与MDM2蛋白对接构象，利用基于受体结构骨架跃迁及优势骨架导向的方法对其进行结构优化，设计合成6类全新骨架衍生物，力求提升活性及成药性。构建荧光偏振法快速、准确、定量评价衍生物抑制活性，使用小鼠乳腺癌转移瘤活体照相模型进行体内评价。以期得到基于MDM2-p53相互作用，活性更强，构效关系明确，药代优异，体内有效抑制肿瘤生长及转移的先导物。

p53是迄今发现与人肿瘤发生相关性最高的抑癌基因。MDM2蛋白与p53结合抑制其功能，导致肿瘤发生及转移，设计阻断两者作用的小分子具有非常重要的意义。本项目根据 LJ1019 与MDM2 蛋白的对接构象，利用基于受体结构，骨架跃迁及优势骨架导向的方法对LJ1019 进行结构优化，设计6 类具有全新骨架类型的化合物，用分子对接的方法对设计化合物进行虚拟筛选，择优进行化合物合成并进行构效关系研究。化合物1b活性最为优异，化合物抗肿瘤活性与靶蛋白亲和力具有相关性，验证了作用机制。综合构效关系及对接构象结果，进行新一轮计算机虚拟筛选，发现一类二芳基α, β不饱和酮类结构活性优异，以其为先导物进行两轮构效关系研究。项目共合成目标化合物212个，其中未见文献报道的新化合物158个，对得到的衍生物进行了系统活性研究，力求得到新型基于抑制MDM2-P53 结合的抗肿瘤先导物。结果显示化合物1、3、8、10、11、15和20对三种实验瘤株均显示出强抑制活性，活性较对照药Nutlin-3a提高50-960倍。化合物10与MDM2蛋白抑制活性ki达到纳摩尔水平，为阳性对照Nutlin-3a的50倍。化合物10的裸鼠体内HCT116细胞系抑瘤率分别为74.6%，略优于阳性对照药伊利替康的抑瘤率为70.2%，且动物耐受良好，体重下降明显低于伊立替康。化合物10抗肿瘤活性优异，作用机制明确，可以作为药物候选物进行后续研究。. 本项目完成了一个完整的研究过程，即包含化合物的设计合成、体外活性测试、体内毒性测试、体内活性以及相关作用机制的验证并确定其作用靶点的完整工作，最终得到的结果与初始的设计思想吻合。