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

MDM2和XIAP是肿瘤细胞中重要的细胞生存蛋白。MDM2作为一种癌蛋白，促进 肿瘤进展主要是通过抑制抑癌基因P53，而抗凋亡蛋白XIAP实现的 通过抑制治疗诱导的细胞凋亡，在耐药的形成中起关键作用。MDM2 已在多种人类癌症中检测到XIAP的过度表达和上调，但在正常人群中未检测到 细胞/组织，肿瘤细胞中MDM2和XIAP的高表达与疾病进展相关 以及糟糕的治疗结果。 我们以前的研究阐明了MDM2 C-末端环区的分子机制 与XIAP IRES mRNA相互作用，稳定MDM2蛋白，增强XIAP的翻译； 这导致MDM2和XIAP的表达同时增加，促进了癌症的进展和 抗药性。我们最近建立了一种用于高通量分析的荧光偏振(FP)分析 筛选(HTS)化学文库，并鉴定出与MDM2环区结合的化合物(MX69) 并阻断或中断其与XIAP IRES mRNA的相互作用。阻止这种交互会导致同时 抑制MDM2和XIAP，导致癌细胞凋亡和死亡。这项提案的总体目标是 目的是开发一种基于MX69支架的潜在靶向药物，以对抗过表达MDM2的肿瘤。 如上所述，这些肿瘤通常还以MDM2依赖的方式上调XIAP，导致 增强了抗药性。 具体地说，我们将基于MX69结构和迭代进行计算机辅助药物设计 优化MDM2结合和抗癌活性(目标1)。我们将定义分子和生物学上的 新型MX69类似物的作用机理(S)--解MDM2的X射线晶体结构 不同的MX69类似物以确认靶点上的MDM2/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)性质；评价其体内抗癌活性 人类小鼠癌症模型；并确定对正常细胞/组织的任何潜在毒性(目标3)。vt.在.的基础上 这个项目完成后，我们将确定MDM2/XIAP作为一种新的双靶向的可行性 治疗机制，并将开发出有希望的小分子抑制剂进一步临床前 评估，不仅是对白血病和神经母细胞瘤的研究，而且对其他癌症类型也是如此。

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.