Dual inhibition of MDM2 and XIAP as a therapeutic strategy in cancer

MDM 2和XIAP是肿瘤细胞中重要的细胞存活蛋白。MDM 2作为一种癌蛋白， 肿瘤进展主要通过抑制肿瘤抑制因子p53，而抗凋亡蛋白XIAP 通过抑制治疗诱导的细胞凋亡，在治疗抗性的发展中起关键作用。MDM2 已经在各种人类癌症中检测到过表达和上调的XIAP，但在正常人中未检测到。 肿瘤细胞中MDM 2和XIAP表达升高与疾病进展相关 治疗效果差。 我们以前的研究阐明了MDM 2 C-末端RING结构域的分子机制， 与XIAP IRES mRNA相互作用，导致MDM 2蛋白的稳定和XIAP翻译的增强; 这导致MDM 2和XIAP的表达同时增加，促进癌症进展， 耐药性我们最近建立了一种用于高通量检测的荧光偏振（FP）检测法。 筛选（HTS）化学文库并鉴定结合MDM 2 RING结构域的化合物（MX69 并阻断或破坏其与XIAP IRES mRNA的相互作用。阻止这种相互作用会导致同时 MDM 2和XIAP的抑制，导致癌细胞凋亡和死亡。本提案的总体目标是 目的是开发一种基于MX69支架的潜在新型靶向药物，用于治疗过表达MDM 2的肿瘤。 如上所述，这些肿瘤通常还以MDM 2依赖性方式上调XIAP，导致肿瘤细胞凋亡。 增强耐药性。 具体来说，我们将基于MX69结构进行计算机辅助药物设计，并迭代 优化MDM 2结合和抗癌活性（目的1）。我们将从分子和生物学的角度 通过解析MDM 2与以下物质复合的X射线晶体结构，研究新型MX69类似物的作用机制： 不同的MX69类似物，以确认靶向MDM 2/XIAP抑制，并评估任何潜在的非特异性 效果（目标2）。我们将进行临床前研究，以评估化合物的稳定性、药代动力学（PK）和 最佳MX69类似物的药效学（PD）特性;使用 人类癌症小鼠模型;并确定对正常细胞/组织的任何潜在毒性（目的3）。后 完成这个项目后，我们将确定双重靶向MDM 2/XIAP作为一种新的治疗方法的可行性。 治疗机制，并将开发有前途的小分子抑制剂，用于进一步的临床前研究。 评估，不仅是白血病和神经母细胞瘤的研究在这个建议，而且在其他癌症类型。

MDM2 and XIAP are important cell-survival proteins in tumor cells. MDM2 acts as an oncoprotein, promoting cancer progression mainly through inhibition of the tumor suppressor p53, while the anti-apoptotic protein XIAP plays a critical role in development of resistance to treatment via inhibition of therapy-induced apoptosis. MDM2 overexpression and upregulated XIAP have been detected in various human cancers but not in normal cells/tissues, and elevated MDM2 and XIAP expression in tumor cells is associated with disease progression and poor treatment outcomes. Our previous studies elucidated a molecular mechanism by which the MDM2 C-terminal RING domain interacts with XIAP IRES mRNA resulting in stabilization of MDM2 protein and enhanced translation of XIAP; this led to concomitantly increased expression of both MDM2 and XIAP, contributing to cancer progression and drug resistance. We have recently established a fluorescence polarization (FP) assay for use in high-throughput screening (HTS) of chemical libraries and identified a compound (MX69) that binds to the MDM2 RING domain and blocks or disrupts its interaction with XIAP IRES mRNA. Blocking this interaction results in simultaneous inhibition of both MDM2 and XIAP, leading to cancer cell apoptosis and death. The overall goal of this proposal is to develop a potential novel targeted agent based on the MX69 scaffold against tumors overexpressing MDM2. As discussed above, these tumors also typically upregulate XIAP in an MDM2-dependent manner, resulting in enhanced drug resistance. Specifically, we will perform computer-aided drug design based on the MX69 structure and iteratively optimize MDM2 binding and anticancer activity (Aim 1). We will define the molecular and biological mechanism(s) of action of novel MX69 analogs by solving the X-ray crystal structures of MDM2 in complex with diverse MX69 analogs to confirm on-target MDM2/XIAP inhibition and to evaluate any potential nonspecific effects (Aim 2). We will perform preclinical studies to assess compound stability, pharmacokinetic (PK), and pharmacodynamic (PD) properties of the best MX69 analogs; to evaluate their anticancer activity in vivo using human cancer-in-mouse models; and to determine any potential toxicity to normal cells/tissues (Aim 3). Upon completion of this project, we will have determined the feasibility of dual targeting MDM2/XIAP as a novel therapeutic mechanism, and will have developed promising small molecule inhibitors for further preclinical evaluations, not only for leukemia and neuroblastoma as studied in this proposal, but also in other cancer types.