Novel NFAT1-MDM2 inhibitor for Breast Cancer Therapy

该项目的长期目标是开发一种新的双靶向治疗策略(MDM2和 NFAT1)用于治疗晚期乳腺癌。晚期乳腺癌患者，特别是那些 对于三阴性乳腺癌(TNBC)，无法从最近开发的靶向治疗中受益。 越来越多的证据表明，几个关键信号通路的功能障碍，包括 NFAT1-MDM2通路与预后不良和化疗/放射耐药有关，为临床提供了新的研究方向 乳腺癌治疗的分子靶点。MDM2癌基因是P53和P53的主要负调控基因 也具有不依赖于P53的致癌活性。它已被认为是一个有效的乳房分子靶点。 癌症治疗。到目前为止，大多数mdm2的小分子抑制剂(SMI)都被设计成 阻断MDM2与P53的结合，因此它们的抗癌活性依赖于 癌细胞中野生型P53的表达。然而，大多数TNBC含有突变型p53，并具有高水平的 MDM2，因此现有的MDM2 SMI预计对这一亚型乳房的疗效很低或没有效果 癌症。因此，发现和开发具有直接作用的新型MDM2抑制剂是非常有必要的 并发挥其抗癌活性，而不依赖于癌细胞的P53状态。激活 NFAT1在乳腺癌中也很常见，特别是在TNBC中，促进了 侵袭性、高级别和晚期肿瘤表型。因此，申请者提议将NFAT1作为一部小说 以此为靶点开发抗乳腺癌药物。到目前为止，还没有特效的NFAT1抑制剂 是为癌症治疗而开发的。具体到这项提案，申请人最近发现，NFAT1 上调MDM2的表达，并促进癌细胞和癌组织中MDM2的过度表达， 包括乳腺癌。根据新生成的初步数据，申请者同时提出 靶向NFAT1和MDM2作为晚期乳腺癌的一种有前景的治疗策略。申请者 最近完成了对基于天然产物的文库的高通量筛选，并识别了 一系列对NFAT1和MDM2都有很强抑制作用的二倍半萜候选化合物。其中一个 先导化合物，日本产甲素(JAPA)，已显示出显著的体外活性、体内效力和最小宿主 乳腺癌模型的毒性。在机制上，JAPA与MDM2和NFAT1蛋白直接结合 高亲和力，并诱导MDM2和NFAT1蛋白不稳定。它还抑制NFAT1介导的MDM2 通过破坏NFAT1与MDM2 P2启动子的结合而转录。这种一流的MDM2抑制剂是 与所有现有的MDM2抑制剂不同。在这份修订后的提案中，申请者将以JAPA为先导 化合物以检验中心假设，即双靶向MDM2和NFAT1代表有效和 晚期乳腺癌治疗的安全策略。假设驱动的三个具体目标是 建议：1)证明JAPA对晚期乳腺癌的治疗潜力；2)阐明 JAPA作为特异性NFAT1-MDM2双链诱导抗乳腺癌作用的分子机制 3)对JAPA的药理和毒理性质进行表征。在完成后 拟议的研究、预期结果将提供有关治疗效果的关键信息和 JAPA的安全性及同时靶向MDM2和NFAT1治疗乳腺癌的价值。这个项目是 非常重要，具有很高的翻译潜力，并将产生一种新的乳腺癌临床候选 这将对病人护理和公共卫生产生重大影响。

The long-term objective of this project is to develop a novel dual-targeting therapeutic strategy (MDM2 and NFAT1) for the treatment of advanced breast cancer. Patients with advanced breast cancer, especially those with triple negative breast cancer (TNBC), cannot benefit from the recently-developed targeted therapies. Accumulating evidence has demonstrated that the dysfunction of several key signaling pathways, including NFAT1-MDM2 pathway, is associated with a poor prognosis and chemo-/radio-resistance, providing novel molecular targets for breast cancer therapy. The MDM2 oncogene is a major negative regulator of p53 and also has p53-independent oncogenic activity. It has been suggested to be a valid molecular target for breast cancer therapy. To date, the majority of small molecule inhibitors (SMIs) of MDM2 have been designed to block the binding of MDM2 to p53, and their anticancer activity was therefore dependent on the expression of wild-type p53 in the cancer cells. However, the majority of TNBC harbors mutant p53 and has high levels of MDM2, so the existing MDM2 SMIs are expected to have low or no efficacy against this subtype of breast cancer. Therefore, it is highly desirable to discover and develop novel MDM2 inhibitors that have direct effects on MDM2 and exert their anticancer activity independent of the p53 status of the cancer cells. The activation of NFAT1 is also commonly observed in breast cancers, especially in TNBC, promoting the development of an invasive, high-grade, and late-stage tumor phenotype. Therefore, the applicants propose NFAT1 as a novel target for the development of anti-breast cancer agents. Thus far, there has been no specific NFAT1 inhibitors developed for cancer therapy. Specific to this proposal, the applicants have recently discovered that NFAT1 up-regulates MDM2 expression and contributes to MDM2 overexpression in cancer cells and cancer tissues, including breast cancer. Based on newly-generated preliminary data, the applicants propose simultaneously targeting NFAT1 and MDM2 as a promising therapeutic strategy for advanced breast cancer. The applicants have recently accomplished a high-throughput screening of a natural product-based library, and have identified a series of disesquiterpenoid candidates with potent inhibitory effects on both NFAT1 and MDM2. One of the lead compounds, Japonicone A (JapA), has shown significant in vitro activity, in vivo efficacy, and minimal host toxicity in breast cancer models. Mechanistically, JapA directly binds to the MDM2 and NFAT1 proteins with high affinity, and induces MDM2 and NFAT1 protein instability. It also inhibits NFAT1-mediated MDM2 transcription by disrupting the binding of NFAT1 to the MDM2 P2 promoter. This first-in-class MDM2 inhibitor is distinct from all of the existing MDM2 inhibitors. In this revised proposal, the applicants will use JapA as a lead compound to test the central hypothesis that the dual targeting MDM2 and NFAT1 represents an effective and safe strategy for the treatment for advanced breast cancer. Three hypothesis-driven specific aims are proposed: 1) To demonstrate the therapeutic potential of JapA for advanced breast cancer; 2) To elucidate the molecular mechanisms by which JapA elicits anti-breast cancer activity as a specific NFAT1-MDM2 dual inhibitor; and 3) To characterize the pharmacological and toxicological properties of JapA. Upon completion of the proposed studies, the anticipated results will provide critical information about the therapeutic efficacy and safety of JapA and the value of simultaneously targeting MDM2 and NFAT1 in breast cancer. This project is highly significant, has high translational potential, and will generate a novel clinical candidate for breast cancer therapy, which would have a major impact on patient care and public health.