Discovery and characterization of small molecules that target the GTPase Ral

摘要

通过Ras GTPase通道进行的信号传导在癌症中经常过度活跃,Ras通道的组成部分作为潜在癌症治疗目标也正在受到广泛研究。在这项研究中,Dan Theodorescu及同事采用一个基于结构的方法发现了能够选择性地以Ral GTPase (Ras信号传导的一个重要下游中介物）rn为目标的小分子抑制剂。这些抑制剂在Ral的不活跃状态与其结合,在细胞分析中和在小鼠中通过生化方式得到了表征。这些第一代抑制剂将是阐释Ras信号传导的宝贵工具,也将是朝着开发用于癌症治疗的Ral特异性药物的方向所迈出的一步。%The Ras-like GTPases RalA and RalB are important drivers of tumour growth and metastasis. Chemicals that block Ral function would be valuable as research tools and for cancer therapeutics. Here we used protein structure analysis and virtual screening to identify drug-like molecules that bind to a site on the GDP-bound form of Ral. The compounds RBC6, RBC8 and RBC10 inhibited the binding of Ral to its effector RALBP1, as well as inhibiting Ral-mediated cell spreading of murine embryonic fibroblasts and anchorage-independent growth of human cancer cell lines. The binding of the RBC8 derivative BQU57 to RalB was confirmed by isothermal titration calorimetry, surface plasmon resonance and ~1H-~(15)N transverse relaxation-optimized spectroscopy (TROSY) NMR spectroscopy. RBC8 and BQU57 show selectivity for Ral relative to the GTPases Ras and RhoA and inhibit tumour xenograft growth to a similar extent to the depletion of Ral using RNA interference. Our results show the utility of structure-based discovery for the development of therapeutics for Ral-dependent cancers.