HTLV I Tax1 protein chemosensitization of p53 mutant tumors

描述（由申请人提供）：我们对人类T细胞白血病病毒I（HTLV I）的研究表明，当将癌蛋白Tax引入p53缺失细胞时，暴露于紫外线损伤后会导致细胞凋亡，导致细胞死亡增加。税收诱导的DNA损伤敏感性揭示了一种消除p53突变体肿瘤抗性的方法。p53突变型肿瘤仍然是人类癌症中最难治疗的肿瘤之一，因为它们对治疗诱导的细胞凋亡具有固有的抗性。p53在大多数人类癌症中突变，包括许多儿科肿瘤。耐药p53突变肿瘤的治疗策略是临床肿瘤学中最重要的问题之一。我们团队的长期目标是研究基因组不稳定性，以了解细胞反应的基本机制及其对临床问题的重要性。Kupfer博士是一位医学科学家，他的实验室专注于利用范可尼贫血模型研究基因组不稳定性和DNA损伤超敏反应。Semmes博士的研究重点是HTLV-1生物学，他在证明Tax诱导的基因组不稳定性作为ATL发展模型方面发挥了重要作用。对基因组不稳定性的共同兴趣促进了这种合作。本申请的目的是了解Tax如何在化疗增敏中发挥作用。这将通过在具有功能上不同的p53背景的模型系统中测试Tax对致敏的作用、以p53非依赖性方式探测Tax诱导的细胞凋亡的机制以及定义这种作用所需的最小结构域来探索。这项研究的中心假设是Tax激活了p53突变细胞中的促凋亡途径，同时促进了p53野生型细胞的耐药性。该提案的基本原理是，通过揭示Tax实现这些功能的机制，我们将揭示用于开发更有效的癌症治疗的靶分子。总之，我们在转化研究方面拥有丰富的经验，并对将实验室观察转移到临床应用方面有着坚实的认识。在目的1中，我们将确定Tax在p53突变细胞中诱导的DNA损伤敏感性谱。这些研究将确定哪种类型的DNA损伤描述了税收效应。此外，我们将确定哪些p53突变体易受这种方法的影响，并缩小负责其影响的特定税收结构域。接下来，我们将测试与包含化学增敏作用的Tax结构域对应的合成肽的使用。接下来，在目标2中，我们将展示Tax在人类癌症小鼠模型中的应用。首先，我们将使用诱导表达Tax的Jurkat细胞作为肿瘤外植体模型来测试Tax的体内效应。接下来，我们将使用在目标1中验证的肽用于对抗p53 -/-小鼠中产生的自发性肿瘤。我们的工作有可能极大地改善治疗耐药癌症的方法。 公共卫生相关性：p53突变常见于肿瘤，是标准化疗耐药的主要原因。因此，p53介导的化学抗性是一个主要的临床肿瘤学问题。在我们对HTLV I Tax蛋白的研究中，我们观察到Tax在p53突变体抗性细胞系中的表达导致对DNA损伤的敏感性增加。在我们提出的工作中，我们假设Tax可以作为一种临床工具，用作化疗增敏剂，以使标准化疗在耐药肿瘤中更有效。我们将证明Tax在细胞系和小鼠肿瘤外植体模型中的使用，作为临床前原则证明，预计将进行最终的临床试验。

DESCRIPTION (provided by applicant): Our work on human T cell leukemia virus I (HTLV I) has revealed that the oncoprotein Tax, when introduced into p53 null cells, causes apoptosis upon exposure to UV damage, resulting in increased cell death. Tax-induced sensitization to DNA damage reveals an approach to abrogate p53 mutant tumor resistance. p53 mutant tumors remain among the most difficult to treat in human cancer because of their inherent resistance to therapy-induced apoptosis. p53 is mutated in a majority of all human cancer, including many pediatric tumors. Development of strategies to treat resistant p53 mutant tumors is one of the most important problems in clinical oncology. The long-term goal of our team is to study genomic instability in order to understand both basic mechanisms of cellular response as well as its importance to clinical problems. Dr. Kupfer is a physician-scientist whose laboratory has focused on genomic instability and DNA damage hypersensitivity utilizing the Fanconi anemia model. A major focus in Dr. Semmes' research is HTLV-1 biology and he was instrumental in demonstrating Tax-induced genomic instability as a model for development of ATL. The common interest in genomic instability has facilitated this collaboration. The objective of this application is to understand how Tax functions in chemosensitization. This will be explored by testing for the Tax effect upon sensitization in model systems with functionally distinct p53 backgrounds, probing for the mechanism of Tax- induced apoptosis in a p53 independent fashion, and defining the minimal domain necessary for such an effect. The central hypothesis for the proposed research is that Tax activates a pro- apoptotic pathway in p53 mutant cells, while promoting resistance in p53 wild type cells. The rationale for this proposal is that by uncovering the mechanism by which Tax accomplishes these functions we will reveal target molecules for the development of more effective cancer therapy. Together, we have extensive experience in translational research and a solid appreciation for moving bench observation to clinical utilization. In Aim 1, we will determine the spectrum of DNA damage sensitivity induced by Tax in p53 mutant cells. These studies will define which types of DNA damage delineate the Tax effect. In addition we will identify which p53 mutants are susceptible to this approach as well as narrow down the specific domain of Tax responsible for its effect. Next, we will test the use of a synthesized peptide corresponding to the domain of Tax that contains the chemosensitization effect. Next, in Aim 2, we will demonstrate the use of Tax in mouse models of human cancer. First we will use Jurkat cells that inducibly express Tax as a tumor explant model to test the Tax effect in vivo. Next we will use the peptides validated in Aim 1 for use against spontaneous tumors arising in p53 -/- mice. Our work has the potential to dramatically improve the approach to treating resistant cancer. PUBLIC HEALTH RELEVANCE: p53 mutations are commonly found in tumors and are a major cause of resistance to standard chemotherapy. Thus, p53 mediated chemoresistance is a major clinical oncology problem. In our work on HTLV I Tax protein, we have observed that expression of Tax in a p53 mutant resistant cell lines results in increased sensitivity to DNA damage. In our proposed work, we hypothesize that Tax could serve as a clinical tool to use as a chemosensitization agent in order to make standard chemotherapy more effective in resistant tumors. We will demonstrate the use of Tax in cell line and mouse tumor explant models as preclinical proof of principle in anticipation of working toward an eventual clinical trial.