基于KRAS-PDEδ蛋白作用的抗肿瘤药物设计、合成及生物活性研究

RAS is an important hub protein in several tyrosine kinase signaling pathways. Previous studies have shown that RAS was a notorious uncogene and was considered to be a driver in many cancer cells. However, due to its small size and protein-binder character, it is difficult to target by small moelcules. This proposal circumvents this with a novel approach, which is inhibition of the protein-protein interaction of RAS and PDEδ.Formation of this complex is a key step for the relocation of Ras protein in the cell membrane. Interferring this critical step will make Ras protein can't recruit other adapter proteins such as Grb2, and therefore interrupting the signaling transduction. Based on a research reported in Nature last year，the inhibitors blocking the formation of this complex effectively down-regulate the RAS signaling transduction, and will be useful for several RAS-dependent cancer therapy. Toward the aim of developing Ras-PDEδ inhbitors, we utilize two methods: 1, by integrating structural-based drug discovery with bioisostere, we will optimize the drug-like properties of known inhibitors; 2, we will also utilize our establised platforms on Fragment-based drug discovery to develop new scaffolds into bioactive inhibitors. By integrating these new drug discovery technologies, we can identify the hit compounds quickly, and optimized the compounds rationally. And we hope these effects can not only provide new treatment for RAS-dependent cancer, but also benefit other researchers for further RAS inhibitor development.

RAS蛋白是多条蛋白络氨酸激酶信号通路中的重要节点蛋白，研究表明它同多种肿瘤的发生、发展有着密切关联，其突变体也是早已确认的致癌基因。但由于RAS蛋白本身难以采用小分子靶向结合，其药物研发一直未取得重要的突破。本申请拟针对RAS-PDEδ这一关键复合物进行抑制剂研发。2013年Nature文章显示，对该复合物进行抑制将有效阻断RAS蛋白在细胞膜上的定位，从而使其无法招募下游蛋白，阻断了RAS进行信号传递的过程，达到抑制肿瘤生长的作用。对该环节的阻断将可能同时抑制多个信号通路，可以治疗多种RAS-依赖型肿瘤生长。为了更好地发现和优化先导化合物，我们将采用两种策略：一方面我们采用基于结构的药物设计结合常规的药物化学优化策略，对现有的小分子机制剂进行骨架改造，优化活性、成药性；另一方面采用我们建立的基于片段的研发平台，快速发现新结构类型，开展深入分子优化改造研究，从而研发Ras抑制剂。

RAS 蛋白是多条蛋白络氨酸激酶信号通路中的重要节点蛋白，研究表明它同多种肿瘤的发生、发展有着密切关联，其突变体也是早已确认的致癌基因。但由于RAS 蛋白本身难以采用小分子靶向结合，其药物研发一直未取得重要的突破。本项目实施中认真按照研究目标和研究方案开展，首先建立了PDEδ-RAS的分子及细胞检测平台，并不断完善现有的片段库，目前片段库的规模已达1500个分子。与此同时我们也开展了针对PDEδ的片段分子药物设计与发现研究，经NMR筛选发现多个片段分子。然后通过采用结构生物学方法获得了其中一个四氮唑片段分子的晶体结构，经结构分析，我们采用骨架跃迁方法获得可以进一步改造三氮唑环。然后经过多轮的分子设计、优化，最终获得了多个分子活性<30nM的化合物，并开展了深入的机制研究。通过片段库建立以及PDEδ-RAS的抑制剂，目前已申请专利2项，同时也发表了文章3篇，另有相关机制研究的工作有待整理发表。经过机制的研究探索，我们发现该靶点的成药性不高，导致分子和细胞活性之间差距较大，是后续研究需要进一步探究的关键所在。总体而言，我们顺利完成了相关的研究工作，并为后续针对KRAS突变的抗肿瘤药物的研究提供了新的方向和研究基础。