Ahmad Md Faiz, Huff Sarah E, Pink John, Alam Intekhab, Zhang Andrew, Perry Kay, Harris Michael E, Misko Tessianna, Porwal Suheel K, Oleinick Nancy L, Miyagi Masaru, Viswanathan Rajesh, Dealwis Chris Godfrey
Department of Pharmacology, School of Medicine, Case Western Reserve University , Cleveland, Ohio 44106, United States.
Department of Chemistry, Case Western Reserve University , Cleveland, Ohio 44106, United States.
J Med Chem. 2015 Dec 24;58(24):9498-509. doi: 10.1021/acs.jmedchem.5b00929. Epub 2015 Dec 9.
Ribonucleotide reductase (RR) catalyzes the rate-limiting step of dNTP synthesis and is an established cancer target. Drugs targeting RR are mainly nucleoside in nature. In this study, we sought to identify non-nucleoside small-molecule inhibitors of RR. Using virtual screening, binding affinity, inhibition, and cell toxicity, we have discovered a class of small molecules that alter the equilibrium of inactive hexamers of RR, leading to its inhibition. Several unique chemical categories, including a phthalimide derivative, show micromolar IC50s and KDs while demonstrating cytotoxicity. A crystal structure of an active phthalimide binding at the targeted interface supports the noncompetitive mode of inhibition determined by kinetic studies. Furthermore, the phthalimide shifts the equilibrium from dimer to hexamer. Together, these data identify several novel non-nucleoside inhibitors of human RR which act by stabilizing the inactive form of the enzyme.
核糖核苷酸还原酶（RR）催化脱氧核苷酸三磷酸（dNTP）合成的限速步骤，是一个已确定的癌症靶点。靶向RR的药物本质上主要是核苷类。在本研究中，我们试图鉴定RR的非核苷小分子抑制剂。通过虚拟筛选、结合亲和力、抑制作用和细胞毒性研究，我们发现了一类小分子，它们改变了RR无活性六聚体的平衡，从而导致其受到抑制。包括邻苯二甲酰亚胺衍生物在内的几个独特化学类别，显示出微摩尔级的半数抑制浓度（IC50）和解离常数（KD），同时表现出细胞毒性。一种活性邻苯二甲酰亚胺在靶向界面结合的晶体结构支持了动力学研究确定的非竞争性抑制模式。此外，邻苯二甲酰亚胺将平衡从二聚体转变为六聚体。总之，这些数据鉴定出了几种新型的人RR非核苷抑制剂，它们通过稳定酶的无活性形式发挥作用。
