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）：Merkel细胞多瘤病毒T抗原和体内项目摘要Merkel细胞癌（MCC）是一种罕见的神经内分泌皮肤肿瘤，由于有效治疗的不可证明性，在晚期疾病阶段的预后较差。大多数MCC携带新型多瘤病毒，默克尔细胞多瘤病毒（MCPYV）和表达两种推定的癌蛋白的序列：MCPYV小型T抗原（Stag）和肿瘤特异性截短的大T抗原（TLTAG）。与其他病毒癌蛋白一样，MCPYV转化的抗原被预计会与包括肿瘤抑制剂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。至少在培养细胞和异种移植物中进行的一些敲低研究支持对MCC肿瘤细胞维持中TLTAG和Stag抗原的需求。此外，在培养的成纤维细胞中的过表达研究指向雄鹿是转化癌基的主要转化，令人惊讶地以PP2A独立的方式运行。相比之下，Stag驱动的成纤维细胞转化严格取决于最近描述的结构域，该结构结合了SCF E3泛素连接酶复合物的FBXW7分量，并导致LTAG和几种细胞肿瘤蛋白的积累，这些细胞是FBXW7 substrates。这些报告为培养的成纤维细胞中雄鹿的转变潜力提供了宝贵的见解，但是评估MCPYV标签是否可以作为体内的致癌驱动器的研究尚未报道。在初步研究中，我们表明，MCPYV雄鹿，但TLTAG也不是全长LTAG，是转化的转化性癌基因，在皮肤和转基因小鼠的口服上皮中，导致增生，导致急性末端分化，DNA损伤反应受损，端粒体受损和凋亡。我们提出了一系列实验，以进一步研究个体的体内转化潜力 MCPYV标签，并在诱导小鼠模型中共表达时测试其功能相互作用。为了研究原始的MCC肿瘤细胞，我们将比较MCPYV TAG在靶向1）增殖与分化表皮的细胞隔室以及2）Merkel细胞祖细胞与分化的默克尔细胞时的增殖。我们还将与有条件的MCPYV TAG转基因小鼠分离出定义的细胞群，并研究它们对细胞培养中TAG表达的反应，从而实现旨在定义转化机制的功能研究，然后可以在体内验证。拟议的研究非常重要，因为它们将通过定义完整动物中MCPYV标签的生物学活性来帮助填补我们的知识的关键空白，从而提供了一套急需的工具，以研究有助于MCPYV相关癌症的发展和维持的因素。此外，这些研究将有助于确定MCPYV标记细胞靶标的靶标的靶标，这些靶标通过非病毒机制进行放松管制可能会推动病毒阴性MCC的发展，并可能对其他类型的癌症的发展产生更大的贡献。最后，提议的工作可能与MCC患者具有直接的翻译相关性，因为它可能导致鉴定新的治疗靶标，并产生急需的小鼠模型进行功能研究和临床前试验。