Novel Compounds to Inactivate Oncogenic Fusion Proteins

描述（由申请人提供）：化疗耐药白血病和肉瘤含有肿瘤特异性染色体易位，这些染色体易位编码融合蛋白，这些融合蛋白仅在肿瘤中表达。融合蛋白提供了显著的肿瘤靶向特异性，并增加了靶向融合蛋白的新疗法既有效又缺乏非特异性毒性的可能性。许多具有转录因子功能的肿瘤特异性融合蛋白是无序蛋白。无序蛋白质缺乏基于结构的药物设计所需的刚性α -螺旋或β -薄片结构。虽然无序蛋白质需要更多的经验方法来发现小分子蛋白质-蛋白质相互作用抑制剂，无序蛋白质的生化特性实际上可能有利于蛋白质-蛋白质相互作用抑制剂的成功。我们将开发一种新的模式来抑制致癌融合蛋白的蛋白-蛋白相互作用。尤文氏肉瘤家族肿瘤（ESFT）包含特征性易位t(11:22)，导致致癌融合蛋白转录因子EWS-FLI1的产生。使EWS-FLI1失活的治疗方法可能解决患者复发性疾病的重大问题。由于EWS-FLI1缺乏内在的酶活性，并且是一种无序蛋白，我们将创建新的蛋白-蛋白相互作用抑制剂来阻止EWS-FLI1与关键蛋白伴侣的结合。我们发现RNA解旋酶A （RHA, p150）是DEAD/H家族成员，可调节基因表达，是EWS-FLI1的关键合作伙伴。EWS-FLI1结合到RHA的一个独特区域，该区域不参与非恶性RHA转录调节。该结合区域的肽模拟物抑制EWS- FLI1与RHA的结合，我们已经发现了一个先导化合物NSC635437，它与肽模拟物具有显著的结构同源性。NSC635437衍生物小分子YK-4-279阻断RHA与EWS-FLI1的结合，诱导ESFT细胞凋亡。我们假设RHA与EWS- FLI1的相互作用产生了一个有效的转录激活因子/辅激活因子复合物，该复合物放大了这两种蛋白的功能并驱动了ESFT的恶性表型。我们的方法将开发阻止EWS-FLI1与RHA结合的试剂，既解决了我们的假设，又创造了一种新的治疗剂。我们将通过研究阻断RHA增强EWS-FLI1功能的作用来实现我们的目标，首先使用肽，然后使用小分子蛋白质-蛋白质相互作用抑制剂。我们将与备受尊敬的药物化学家米尔顿·布朗博士合作，对我们的先导化合物进行化学优化。我们的工作对更大范围的肿瘤具有广泛的适用性，为发育治疗提供了新的范例。这种创建EWS-FLI1小分子抑制剂的范例可用于其他易位定义的恶性肿瘤，如化疗耐药癌、肉瘤和白血病。因此，未来的工作将对许多难以治疗的肿瘤患者产生积极影响，从而降低死亡率和发病率。

DESCRIPTION (provided by applicant): Chemotherapy-resistant leukemias and sarcomas contain tumor-specific chromosomal translocations that encode fusion-proteins and these fusion-proteins are expressed only in the tumor. A fusion-protein provides significant tumor target specificity and increases the likelihood that novel therapies targeting the fusion-protein will be both effective and lack non-specific toxicity. Many of the tumor-specific fusion-proteins that function as transcription factors are disordered proteins. Disordered proteins lack the rigid alpha-helical or beta sheet structures required for structure-based drug design. While disordered proteins require a more empiric approach to the discovery of small molecule protein-protein interaction inhibitors, the biochemical properties of disordered proteins may actually favor the success of protein-protein interaction inhibitors. We will develop a novel paradigm to inhibit the protein-protein interaction of an oncogenic fusion protein. The Ewing's Sarcoma Family of Tumors (ESFT) contains a characteristic translocation, t(11:22), which leads to the oncogenic, fusion-protein, transcription factor EWS-FLI1. Therapies that inactivate EWS-FLI1 might address the significant problem of recurrent disease for patients. Since EWS-FLI1 lacks intrinsic enzymatic activity, and is a disordered protein, we will create novel protein-protein interaction inhibitors to block EWS-FLI1 binding to critical protein partners. We identified RNA Helicase A (RHA, p150), a DEAD/H family member that modulates gene expression, as a critical partner of EWS-FLI1. EWS-FLI1 binds to a unique region of RHA that is NOT involved in non-malignant RHA transcriptional modulation. A peptide mimic of this binding region inhibits EWS- FLI1 binding to RHA and we have discovered a lead compound, NSC635437, which has significant structural homology with the peptide mimic. A derivative small molecule of NSC635437, YK-4-279, blocks RHA binding to EWS-FLI1 and induces apoptosis in ESFT cells. We hypothesize that the interaction of RHA with EWS- FLI1 results in a potent transcriptional activator/coactivator complex, which amplifies the functions of both proteins and drives the malignant phenotype of ESFT. Our approach will develop reagents that prevent the binding of EWS-FLI1 to RHA, both to address our hypothesis and create a new therapeutic agent. We will accomplish our objectives by examining the effects of blocking RHA from enhancing EWS-FLI1 function, first using a peptide and then with small molecule protein-protein interaction inhibitors. We will work together with Dr. Milton Brown, a highly regarded medicinal chemist, to chemically optimize our lead compound. Our work has broad applicability to a larger group of tumors, serving as a new paradigm for developmental therapeutics. This paradigm to create small molecule inhibitors of EWS-FLI1 could be used for other translocation-defined malignancies such as chemotherapy-resistant carcinomas, sarcomas and leukemias. Therefore, future work would have a strong potential for a positive impact upon many patients with difficult to treat tumors leading to reduced mortality and morbidity.