Establishing MAGE-A4/RAD18 as a novel cancer-specific chemotherapeutic target

联系PD/PI：Vaziri、Cyrus 总结 我们对癌细胞如何获得DNA损伤耐受性的理解存在根本性的差距， 避免化疗（称为“化疗耐药”）。我们对DNA损伤耐受性的知识缺口（以及 它在正常细胞和肿瘤细胞之间的区别），限制了我们杀死肿瘤而不引起副作用的能力 对正常健康组织的毒性。我们的长期目标是解决肿瘤细胞 耐受治疗，并确定新的分子脆弱性，可以专门针对改善 治疗本研究的目的是确定一种新的肿瘤特异性化疗耐药机制， 确立了其作为治疗靶点的易处理性。值得注意的是，我们发现黑色素瘤抗原A4 （MAGE-A4，癌症/睾丸抗原或'CTA'）是DNA修复蛋白的活化结合配偶体 RAD 18（E3泛素连接酶）。MAGE-A4不存在于所有正常体细胞中，但在病理学上激活 癌细胞中的DNA修复MAGE-A4还激活E3连接酶TRIM 69，其赋予对有丝分裂的抗性。 纺锤体毒素MAGE-A4表达与患者预后不良相关，但其对患者预后的潜在影响 在生理环境中肿瘤对化疗的反应性尚未测试。基于令人兴奋和 令人信服的初步研究，我们将测试中心假设，MAGE-A4病理重编程 肿瘤中的泛素信号传导以赋予对基因毒素和纺锤体毒物的化学抗性。其基本原理是 确定MAGE-A4对化疗耐药性的贡献将允许非常特异性的治疗， 针对肿瘤细胞独特的分子脆弱性的策略。具体目标是：SA 1定义 病理激活的DNA修复对体内化学抗性的贡献。SA 2建立化学品 MAGE-A4/RAD 18作为治疗靶点的易处理性。SA 3机械定义MAGE-A4/TRIM 69 在有丝分裂进程和对纺锤体毒素的抗性中起作用。在SA 1中，我们将使用新的转基因 小鼠和原位肺癌模型，以确定MAGE-A4/RAD 18如何影响对 体内化疗。在SA 2中，我们将筛选肽噬菌体展示文库以鉴定 结合MAGE-A4并破坏MAGE-A4/RAD 18相互作用。生物活性MAGE-A4抑制剂肽将被 进行抗肿瘤活性测试。在SA 3中，我们将定义MAGE-A4在调节TRIM 69和TRIM 68中的新作用。 赋予对纺锤体毒素的抗性。我们将机械地定义MAGE-A4/TRIM 69信号传导 途径，并确定其在治疗性紫杉烷耐受性中的作用。这些实验可能会建立 MAGE-A4作为改善癌细胞化疗耐药性的药物靶点，作为关键的门户 在药物发现过程中。提出的想法和研究是创新的，因为它们是第一个 研究以测试CTA的生物活性如何影响癌症治疗。拟议的工作意义重大 因为它将为由于病理性泛素信号传导导致的化学抗性提供新的范例， 直接用于治疗耐药癌症的新型靶向疗法。 项目总结/摘要

Contact PD/PI: Vaziri, Cyrus SUMMARY There are fundamental gaps in our understanding of how cancer cells acquire DNA damage-tolerance and evade chemotherapy (termed ‘chemoresistance’). The gaps in our knowledge of DNA damage tolerance (and how it differs between normal and neoplastic cells), limit our ability to kill tumors without causing side effect toxicities to normal healthy tissues. Our long-term goals are to solve the problem of how neoplastic cells tolerate therapy, and identify new molecular vulnerabilities that can be specifically targeted for improved treatment. The objective here is to define a novel tumor-specific mechanism of chemoresistance and to establish its tractability as a therapeutic target. Remarkably, we discovered that Melanoma Antigen-A4 (MAGE-A4, a Cancer/Testes Antigen or 'CTA') is an activating binding partner of the DNA repair protein RAD18 (an E3 ubiquitin ligase). MAGE-A4 is absent from all normal somatic cells but pathologically activates DNA repair in cancer cells. MAGE-A4 also activates the E3 ligase TRIM69 which confers resistance to mitotic spindle poisons. MAGE-A4 expression is associated with poor patient prognosis yet its potential impact on the responsiveness of tumors to chemotherapy in a physiological setting is untested. Based on exciting and compelling preliminary studies, we will test the central hypothesis that MAGE-A4 pathologically reprograms ubiquitin signaling in tumors to confer chemoresistance to genotoxins and spindle poisons. The rationale is that defining the contribution of MAGE-A4 to chemoresistance will allow extraordinarily specific therapeutic strategies that target a unique molecular vulnerability of neoplastic cells. The Specific Aims are: SA1 Define contribution of pathologically-activated DNA repair to chemoresistance in vivo. SA2 Establish chemical tractability of MAGE-A4/RAD18 as a therapeutic target. SA3 Mechanistically define MAGE-A4/TRIM69 functions in mitotic progression and resistance to spindle poisons. In SA1 We will use a new transgenic mouse and orthotopic lung cancer models to determine how MAGE-A4/RAD18 impacts responses to chemotherapy in vivo. In SA2 we will screen peptide phage display libraries to identify sequence motifs that bind MAGE-A4 and disrupt the MAGE-A4/RAD18 interaction. Bioactive MAGE-A4 inhibitor peptides will be tested for anti-neoplastic activity. In SA3 we will define a novel role of MAGE-A4 in regulating TRIM69 and conferring resistance to spindle poisons. We will mechanistically define the MAGE-A4/TRIM69 signaling pathway and establish its role in tolerance of therapeutic taxanes. These experiments will likely establish MAGE-A4 as a druggable target for ameliorating chemoresistance in cancer cells, serving as a crucial gateway in the drug discovery process. The proposed ideas and research are innovative because they are the first studies to test how biological activities of CTAs affect cancer therapy. The proposed work is significant because it will provide new paradigms for chemoresistance due to pathological ubiquitin signaling leading directly to novel targeted therapies for chemoresistant cancer. Project Summary/Abstract