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型(HTLV I)的研究表明，当将癌蛋白Tax引入P53缺失细胞时，会导致暴露在紫外线损伤下的细胞凋亡，导致细胞死亡增加。TAX诱导的DNA损伤敏感性揭示了一种消除p53突变肿瘤耐药性的方法。P53突变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抵抗力。P53在大多数人类癌症中都发生了突变，包括许多儿科肿瘤。开发治疗耐药的p53突变肿瘤的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的不稳定性，以了解细胞反应的基本机制及其对临床问题的重要性。库普费尔博士是一名内科科学家，他的实验室利用范科尼贫血模型专注于基因组不稳定性和DNA损伤过敏性。塞梅斯博士的主要研究重点是HTLV-1生物学，他在展示税收诱导的基因组不稳定作为ATL发展的模型方面发挥了重要作用。对基因组不稳定的共同兴趣促进了这种合作。本应用程序的目的是了解税收在化疗增敏中的作用。这将通过在具有不同P53功能背景的模型系统中测试税收对敏化的影响，以P53独立的方式探索税收诱导细胞凋亡的机制，并定义这种效应所需的最小结构域。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。这项提议的基本原理是，通过揭示税收实现这些功能的机制，我们将揭示开发更有效的癌症治疗的目标分子。总而言之，我们在转化性研究方面拥有丰富的经验，并对将台式观察转移到临床应用有着坚实的认识。在目标1中，我们将测定紫杉醇对突变型p53细胞DNA损伤敏感性的谱。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突变容易受到这种方法的影响，并缩小对其影响的特定税收领域。接下来，我们将测试与包含化学增敏作用的Tax结构域相对应的合成肽的使用。接下来，在目标2中，我们将演示TAX在人类癌症小鼠模型中的使用。首先，我们将使用可诱导表达TAX的Jurkat细胞作为肿瘤移植模型，在体内测试TAX效应。接下来，我们将使用在AIM 1中验证的多肽来治疗P53-/-小鼠的自发性肿瘤。我们的工作有可能极大地改进治疗耐药癌症的方法。 与公共卫生相关：P53突变在肿瘤中常见，是对标准化疗产生抗药性的主要原因。因此，P53介导的化疗耐药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突变耐药细胞系中的表达导致对DNA损伤的敏感性增加。在我们提议的工作中，我们假设TAX可以作为一种临床工具用作化疗增敏剂，以便使标准化疗对耐药肿瘤更有效。我们将展示TAX在细胞系和小鼠肿瘤移植模型中的应用，作为临床前的原则证据，以期最终进行临床试验。

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.