Novel Compounds to Inactivate Oncogenic Fusion Proteins

描述(申请人提供)：化疗耐药白血病和肉瘤含有肿瘤特异的染色体易位，编码融合蛋白，这些融合蛋白只在肿瘤中表达。融合蛋白提供了显著的肿瘤靶点特异性，并增加了针对融合蛋白的新疗法既有效又缺乏非特异性毒性的可能性。许多发挥转录因子功能的肿瘤特异性融合蛋白都是无序蛋白。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-折叠结构。虽然无序蛋白质需要更经验性的方法来发现小分子蛋白质-蛋白质相互作用抑制剂，但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范例来抑制致癌融合蛋白的蛋白质-蛋白质相互作用。尤文氏肉瘤家族(ESFT)包含一个特征性易位，t(11：22)，导致致癌、融合蛋白、转录因子EWS-FLI1。灭活EWS-FLI1的治疗方法可能会解决患者复发这一重大问题。由于EWS-FLI1缺乏内在的酶活性，并且是一种无序蛋白质，我们将创造新的蛋白质-蛋白质相互作用抑制剂来阻止EWS-FLI1与关键蛋白质伙伴的结合。我们发现RNA解旋酶A(RHA，P150)是EWS-FLI1的关键合作伙伴，它是DEAD/H家族中调节基因表达的成员。EWS-FLI1与RHA的一个独特区域结合，该区域不参与非恶性RHA的转录调控。该结合区的模拟肽抑制EWS-FLI1与RHA的结合，我们发现了一个先导化合物NSC635437，它与模拟的肽具有显著的结构同源性。NSC635437的衍生小分子YK-4-279可阻断RHA与EWS-FLI1的结合并诱导ESFT细胞凋亡。我们假设RHA与EWS-FLI1的相互作用导致了一个强大的转录激活因子/辅助激活因子复合体，该复合体放大了这两种蛋白的功能，并推动了ESFT的恶性表型。我们的方法将开发防止EWS-FLI1与RHA结合的试剂，以解决我们的假设并创造一种新的治疗剂。我们将通过检测阻断RHA增强EWS-FLI1功能的效果来实现我们的目标，首先使用多肽，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，从化学上优化我们的先导化合物。我们的工作对更大的肿瘤群体具有广泛的适用性，为发育疗法提供了一个新的范例。这种创造EWS-FLI1小分子抑制剂的范例可以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，未来的工作将有很大的潜力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。公共卫生相关性：癌症患者需要新的靶向治疗，以提高存活率并减少治疗的副作用。尤文氏肉瘤家族肿瘤(ESFT)是发生在儿童、青少年和青壮年的高度恶性的骨和软组织肿瘤。肿瘤通常生长在靠近骨骼的地方，但也可以软组织肿块的形式出现。目前ESFT患者的标准治疗方案是五种药物方案，持续约9个月。出现局限性ESFT的患者有大约70%的无病存活率。尽管进行强化治疗，出现转移性ESFT的患者预后较差(无瘤存活率为20%)。这些临床应答率在过去十年中持续存在，即使在剂量强化化疗和骨髓移植之后也是如此。因此，我们需要找到新的治疗方法，既能减少治疗相关的发病率，又能提高总体生存率。幸运的是，ESFT包含一个理想的分子靶点。不幸的是，尽管人们知道灭活这个理想的靶点会导致ESFT细胞死亡，但灭活分子靶点的策略还没有带到临床上。该项目将具体解决对ESFT和大量具有染色体易位的相关恶性肿瘤的新靶向治疗的需求。

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. PUBLIC HEALTH RELEVANCE:New targeted therapies are needed for cancer patients that improve survival and decrease side-effects of therapy. Ewing's Sarcoma Family of Tumors (ESFT) are highly malignant tumors of bone and soft tissue that occur in children, adolescents, and young adults. The tumors often grow in close proximity to bone, but can occur as a soft-tissue mass. Current standard therapy for ESFT patients is a five-drug regimen that lasts for approximately 9 months. Patients who present with localized ESFT have approximately 70% disease-free survival. Patients who present with metastatic ESFT have a poor prognosis (20% disease-free survival) despite intensive therapy. These clinical response rates have persisted for the past decade, even after dose-intensifying chemotherapy and bone marrow transplantation. Therefore, we need to discover novel therapeutic approaches to both reduce treatment related morbidity and improve overall survival. Fortunately, ESFT contain an ideal molecular target. Unfortunately, despite knowledge that inactivation of this ideal target causes ESFT cell death, strategies to inactivate the molecular target have not been brought to the clinic. This project will specifically address the need for new targeted therapies for ESFT and a large number of related malignancies that have chromosomal translocations.