Merkel cell polyomavirus T antigens in tumorigenesis

默克尔细胞多瘤病毒 T 抗原在肿瘤发生中的作用

基本信息

批准号：
8833939
负责人：
ANDRZEJ A. DLUGOSZ
金额：
$ 35.52万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-01-01 至 2019-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8833939
关键词：
Adult Animal Model Animals Antigen Targeting Antigens Apoptosis Automobile Driving Binding Biological Brain Neoplasms C-terminal Cancer Etiology Carcinoma in Situ Cell Culture Techniques Cell Maintenance Cells Complex Cultured Cells DNA Damage Data Development Distant Metastasis Embryo Employee Strikes Epidermis Epithelial Epithelium Fibroblasts Gene Expression Profile Genetically Engineered Mouse Growth Human Human Papillomavirus Hyperplasia In Situ In Vitro Individual Infection Knowledge Large T Antigen Lead Length Lesion Light Link Maintenance Malignant Neoplasms Malignant neoplasm of cervix uteri Merkel Cells Merkel cell carcinoma Modeling Mus Mutagenesis Mutation Neoplastic Cell Transformation Neuroendocrine Tumors Neurosecretory Systems Oncogene Proteins Oncogenes Oncogenic Patients Phenotype Play Polyomavirus Polyomavirus Transforming Antigens Population Preclinical Testing Process Proliferating Property Protein Phosphatase 2A Regulatory Subunit PR53 Proteins RB1 gene Reporting Role SKP Cullin F-Box Protein Ligases Series Signal Pathway Simian virus 40 Skin Skin Cancer Skin Neoplasms Small T Antigen Squamous cell carcinoma Staging Survival Rate Testing Transgenic Mice Transgenic Organisms Tumor Suppressor Proteins Viral Viral Proteins Viral Tumor Antigens Virus Work Xenograft procedure advanced disease base cancer type cell transformation cellular targeting effective therapy in vivo insight keratinocyte knock-down mouse model neoplastic neoplastic cell new therapeutic target novel oral cavity epithelium outcome forecast overexpression postnatal preclinical study progenitor public health relevance research study response targeted treatment tool tumor tumorigenesis ubiquitin-protein ligase virus development

项目摘要

DESCRIPTION (provided by applicant): Merkel cell polyomavirus T antigens and neoplastic transformation in vivo Project Summary Merkel cell carcinoma (MCC) is a rare neuroendocrine skin tumor with a poor prognosis at advanced disease stages due to the unavailability of effective treatments. Most MCCs carry sequences from a novel polyomavirus, Merkel cell polyomavirus (MCPyV), and express two putative oncoproteins: MCPyV small T antigen (sTAg) and tumor-specific truncated large T antigen (tLTAg). Like other viral oncoproteins, MCPyV transforming antigens are predicted to interact with multiple cellular proteins including tumor suppressors: tLTAg targets RB1 while sTAg targets the PP2A complex. At least some knock-down studies in cultured cells and xenografts support a requirement for tLTAg and sTAg antigens in MCC tumor cell maintenance. In addition, overexpression studies in cultured fibroblasts point to stAg as the predominant transforming oncogene which, surprisingly, operates in a PP2A-independent manner. In contrast, sTAg-driven fibroblast transformation is strictly dependent on a recently-described domain that binds the Fbxw7 component of the SCF E3 ubiquitin ligase complex and leads to accumulation of LTAg and several cellular oncoproteins that are Fbxw7 substrates. These reports have provided valuable insight into the transforming potential of sTAg in cultured fibroblasts, but studies assessing whether MCPyV TAgs can function as oncogenic drivers in vivo have not yet been reported. In preliminary studies we show that MCPyV sTAg, but neither tLTAg nor full-length LTAg, is a potent transforming oncogene in skin and oral epithelia of transgenic mice, leading to striking hyperplasia, impaired terminal differentiation, a DNA damage response, and apoptosis. We propose a series of experiments to further study the in vivo transformation potential of individual MCPyV TAgs, and to test their functional interaction when co-expressed in inducible mouse models. To investigate the MCC tumor cell of origin, we will compare MCPyV TAg transforming potential when targeted to 1) proliferating versus differentiating cellular compartments of epidermis, and 2) Merkel cell progenitors versus differentiated Merkel cells. We will also isolate defined cell populations from conditional MCPyV TAg transgenic mice and study their response to TAg expression in cell culture, enabling functional studies aimed at defining mechanisms of transformation which can then be verified in vivo. The proposed studies are highly significant since they will help fill a critical gap in our knowledge by defining the biological activity of MCPyV TAgs in intact animals, providing a much-needed set of tools for studying factors contributing to the development and maintenance of MCPyV-associated cancer. In addition, these studies will help identify MCPyV TAg cellular targets whose deregulation via non-viral mechanisms may drive the development of virus-negative MCC, and may contribute more generally to the development of other types of cancer. Finally, the proposed work is likely to have direct translational relevance to MCC patients, as it may lead to the identification of new therapeutic targets and yield much-needed mouse models for functional studies and preclinical trials.

描述（由申请人提供）：默克尔细胞多瘤病毒T抗原和体内肿瘤转化项目摘要默克尔细胞癌（MCC）是一种罕见的神经内分泌皮肤肿瘤，由于无法获得有效的治疗，在疾病晚期阶段预后较差。大多数 MCC 携带新型多瘤病毒——默克尔细胞多瘤病毒 (MCPyV) 的序列，并表达两种假定的癌蛋白：MCPyV 小 T 抗原 (sTAg) 和肿瘤特异性截短大 T 抗原 (tLTAg)。与其他病毒癌蛋白一样，MCPyV 转化抗原预计会与包括肿瘤抑制因子在内的多种细胞蛋白相互作用：tLTAg 靶向 RB1，而 sTAg 靶向 PP2A 复合物。至少一些培养细胞和异种移植物的敲低研究支持 MCC 肿瘤细胞维持中需要 tLTAg 和 sTAg 抗原。此外，培养成纤维细胞的过度表达研究表明 stAg 是主要的转化癌基因，令人惊讶的是，它以不依赖 PP2A 的方式发挥作用。相比之下，sTAg 驱动的成纤维细胞转化严格依赖于最近描述的一个结构域，该结构域结合 SCF E3 泛素连接酶复合物的 Fbxw7 成分，并导致 LTAg 和作为 Fbxw7 底物的几种细胞癌蛋白的积累。这些报告为 sTAg 在培养的成纤维细胞中的转化潜力提供了有价值的见解，但评估 MCPyV TAg 是否可以在体内充当致癌驱动因素的研究尚未报道。在初步研究中，我们表明，MCPyV sTAg（但不是 tLTAg 和全长 LTAg）是转基因小鼠皮肤和口腔上皮中的有效转化癌基因，导致显着增生、终末分化受损、DNA 损伤反应和细胞凋亡。我们提出了一系列实验来进一步研究个体的体内转化潜力 MCPyV 标签，并测试它们在诱导型小鼠模型中共表达时的功能相互作用。为了研究 MCC 肿瘤细胞的起源，我们将比较针对 1) 增殖与分化的表皮细胞区室，以及 2) 默克尔细胞祖细胞与分化的默克尔细胞时的 MCPyV TAg 转化潜力。我们还将从有条件的 MCPyV TAg 转基因小鼠中分离出确定的细胞群，并研究它们对细胞培养物中 TAg 表达的反应，从而实现旨在确定转化机制的功能研究，然后可以在体内进行验证。拟议的研究非常重要，因为它们将通过定义完整动物中 MCPyV 标签的生物活性来帮助填补我们知识中的一个关键空白，为研究有助于 MCPyV 相关的发展和维持的因素提供一套急需的工具。癌症。此外，这些研究将有助于确定 MCPyV TAg 细胞靶点，其通过非病毒机制解除管制可能会推动病毒阴性 MCC 的发展，并可能更广泛地促进其他类型癌症的发展。最后，拟议的工作可能与 MCC 患者具有直接的转化相关性，因为它可能导致新治疗靶点的识别，并产生功能研究和临床前试验急需的小鼠模型。