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

联系PD/PI：Vaziri，Cyrus 摘要 在我们对癌细胞如何获得DNA损伤耐受性和 逃避化疗(称为“化疗耐药”)。我们在DNA损伤耐受性方面的知识差距(和 正常细胞和肿瘤细胞之间的区别)，限制了我们杀死肿瘤的能力，而不会产生副作用 对正常健康组织的毒性。我们的长期目标是解决肿瘤细胞如何 耐受治疗，识别新的分子脆弱性，可以专门针对这些脆弱性进行改进 治疗。这里的目标是定义一种新的肿瘤特异性化疗耐药机制，并 确定它的易操纵性作为治疗目标。值得注意的是，我们发现黑色素瘤抗原-A4 (MAGE-A4，一种癌症/睾丸抗原或CTA)是DNA修复蛋白的激活结合伙伴 RAD18(一种E3泛素连接酶)。MAGE-A4在所有正常体细胞中都不存在，但在病理上被激活 癌细胞中的DNA修复。MAGE-A4还激活E3连接酶TRIM69，该连接酶可抵抗有丝分裂 纺锤形毒药。MAGE-A4的表达与患者预后不良有关，但其对 在生理环境中，肿瘤对化疗的反应性未经测试。基于令人兴奋的和 令人信服的初步研究，我们将检验MAGE-A4在病理上重新编程的中心假设 肿瘤中泛素信号转导对基因毒素和纺锤体毒药的化疗耐药。其基本原理是 明确MAGE-A4对化疗耐药的贡献将允许非常特异的治疗 针对肿瘤细胞独特的分子脆弱性的策略。具体目标是：SA1定义 病理激活的DNA修复在体内化疗耐药中的作用。SA2建立化学物质 MAGE-A4/RAD18作为治疗靶点的可操作性。SA3机械地定义MAGE-A4/TRIM69 在有丝分裂进程中的作用和对纺锤体毒药的抵抗。在SA1中我们将使用一种新的转基因 建立小鼠和原位肺癌模型以确定MAGE-A4/RAD18对 体内化疗。在SA2中，我们将筛选多肽噬菌体展示文库，以确定 结合MAGE-A4并破坏MAGE-A4/RAD18的相互作用。MAGE-A4生物活性抑制物肽 进行了抗肿瘤活性测试。在SA3中，我们将定义MAGE-A4在调节TRIM69和 赋予对纺锤体毒物的抵抗力。我们将机械地定义MAGE-A4/TRIM69信令 途径，并确定其在治疗紫杉烷耐受中的作用。这些实验很可能会确定 MAGE-A4作为改善癌细胞化疗耐药性的可用药靶点，是一个重要的门户 在药物发现过程中。提出的想法和研究是创新的，因为它们是第一次 测试CTA生物活性如何影响癌症治疗的研究。拟议的工作意义重大 因为它将为病理性泛素信号传导导致的化疗耐药提供新的范例 直接用于化疗耐药癌症的新靶向治疗。 项目摘要/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