Division of Neuro-oncology, Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama.
Drug Discovery Division, Chemistry Department, Southern Research Institute, Birmingham, Alabama.
Cancer Res. 2021 Apr 15;81(8):2220-2233. doi: 10.1158/0008-5472.CAN-20-2858. Epub 2021 Feb 18.
The development of novel therapeutics that exploit alterations in the activation state of key cellular signaling pathways due to mutations in upstream regulators has generated the field of personalized medicine. These first-generation efforts have focused on actionable mutations identified by deep sequencing of large numbers of tumor samples. We propose that a second-generation opportunity exists by exploiting key downstream "nodes of control" that contribute to oncogenesis and are inappropriately activated due to loss of upstream regulation and microenvironmental influences. The RNA-binding protein HuR represents such a node. Because HuR functionality in cancer cells is dependent on HuR dimerization and its nuclear/cytoplasmic shuttling, we developed a new class of molecules targeting HuR protein dimerization. A structure-activity relationship algorithm enabled development of inhibitors of HuR multimer formation that were soluble, had micromolar activity, and penetrated the blood-brain barrier. These inhibitors were evaluated for activity validation and specificity in a robust cell-based assay of HuR dimerization. SRI-42127, a molecule that met these criteria, inhibited HuR multimer formation across primary patient-derived glioblastoma xenolines (PDGx), leading to arrest of proliferation, induction of apoptosis, and inhibition of colony formation. SRI-42127 had favorable attributes with central nervous system penetration and inhibited tumor growth in mouse models. RNA and protein analysis of SRI-42127-treated PDGx xenolines across glioblastoma molecular subtypes confirmed attenuation of targets upregulated by HuR. These results highlight how focusing on key attributes of HuR that contribute to cancer progression, namely cytoplasmic localization and multimerization, has led to the development of a novel, highly effective inhibitor. SIGNIFICANCE: These findings utilize a cell-based mechanism of action assay with a structure-activity relationship compound development pathway to discover inhibitors that target HuR dimerization, a mechanism required for cancer promotion.
新型治疗方法的开发利用了由于上游调节剂突变导致的关键细胞信号通路激活状态的改变，从而产生了个性化医学领域。这些第一代努力的重点是通过对大量肿瘤样本进行深度测序来识别可操作的突变。我们提出，通过利用导致肿瘤发生的关键下游“控制节点”，存在第二代机会，这些节点由于上游调节和微环境影响的丧失而被不当激活。RNA 结合蛋白 HuR 就是这样一个节点。由于 HuR 在癌细胞中的功能依赖于 HuR 二聚化及其核/细胞质穿梭，我们开发了一种靶向 HuR 蛋白二聚化的新型分子。结构活性关系算法使 HuR 多聚体形成抑制剂的开发成为可能，这些抑制剂具有可溶性、具有微摩尔活性并且可以穿透血脑屏障。这些抑制剂在基于细胞的 HuR 二聚化活性验证和特异性的稳健测定中进行了评估。符合这些标准的 SRI-42127 分子抑制了原发性患者来源的胶质母细胞瘤异种系 (PDGx) 中 HuR 的多聚体形成，导致增殖停滞、凋亡诱导和集落形成抑制。SRI-42127 具有良好的中枢神经系统穿透性，并抑制了小鼠模型中的肿瘤生长。对 SRI-42127 处理的 PDGx 异种系的 RNA 和蛋白质分析证实，HuR 上调的靶标受到抑制。这些结果强调了如何专注于导致癌症进展的 HuR 的关键属性，即细胞质定位和多聚化，从而开发出一种新型、高效的抑制剂。意义：这些发现利用基于细胞的作用机制测定和结构活性关系化合物开发途径来发现靶向 HuR 二聚化的抑制剂，这是促进癌症的必要机制。
