新型WDR5蛋白Win site抑制剂的合理设计、合成及其抗肿瘤活性研究

WDR5作为一种表观调控因子，尤其通过Win site与组蛋白甲基转移酶MLL1相互作用，参与众多肿瘤的发生、发展过程。但WDR5 Win site抑制剂研究尚处于起步阶段，目前没有药物进入临床研究。本项目拟以申请者前期筛选获得的新骨架WDR5 Win site抑制剂—雷贝拉唑为苗头化合物，深度解析苗头化合物与Win site的结合模式，分区域对苗头化合物进行合理结构优化，探讨构效关系，获得结构新颖、活性优异、成药性良好的WDR5抑制剂；探索抑制剂对WDR5-MLL1相互作用的调控功能，阐明作用机制；应用活性优异的抑制剂扩大对肿瘤细胞株的抗增殖活性筛选；最后构建抑制剂敏感的肿瘤细胞裸鼠移植瘤模型，探索抑制剂的体内抗肿瘤活性。该研究不仅丰富了WDR5 Win site小分子抑制剂的化学结构类型，还为WDR5作为新型抗肿瘤靶标的成药性提供理论依据，同时发掘质子泵抑制剂潜在的老药新用临床用途。

WDR5 is an epigenetic regulator that has received considerable attention as a cancer target. The most obvious route to pharmacologically inhibit WDR5 is via the Win site. Although the functions of the Win site are not fully understood, it is clear that it plays an important role in the HMT activity of complexes carrying the MLL1 protein. However, only few chemical structure types of Win site inhibitors were reported, which leads to the unclarity binding mode analysis between blockers and WDR5 protein. To date, the inhibitors have not entered clinical studies and even lack in vivo efficacy studies. Here, Rabeprazole, discovered as a WDR5 Win site inhibitor by our group using cellular-based method and fluorescence polarization-based screening, is chosen as a hit compound for further optimization. The X-ray co-crystal structure analysis or the docking study reveals the binding interactions between Rabeprazole and WDR5 at the Win site, which contributes to the optimization of structure-based drug design approach to obtain novel scaffold compounds with high affinities, high cellular activities against MLL fusion leukemia cell lines and favorable physicochemical properties. The analysis of structure-activity and structure-property relationships is informative for the subsequent development of small molecule blockers. Then we will verify whether the inhibitors are able to engage the Win site of WDR5 in cells and specifically block interaction of MLL1-WDR5 protein-protein interaction, and modulate the HMT activity of MLL1 complex and downstream genes. Next, we will further assess whether blocking the Win site of WDR5 by a small molecule can inhibit the proliferation of other cancer cells, such as leukemia cells containing different p53 status. We would further examine the metabolic stability of inhibitors in vitro and pharmacokinetic profiles. Finally, compounds with the potent inhibitory activity and drug-like properties both in vitro and in vivo, are further assessed in xenograft model to examine their antitumor efficacy and the mechanism in vivo. This project not only enriches the chemical structure library of WDR5 small molecule inhibitors, but also provides theoretical basis for WDR5 serving as a new anti-tumor target. This study also provides new insight for the drug reposition of proton pump inhibitors.