Cell fate decisions in Merkel cell carcinoma initiation and maintenance

默克尔细胞癌发生和维持的细胞命运决定

• 批准号: 9973721
• 负责人: ANDRZEJ A. DLUGOSZ
• 金额: $ 53.15万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-20 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9973721
• 关键词: Adult; Aggressive behavior; Alleles; Antigen Targeting; Antigens; Behavior; Biological; Cancer Etiology; Cancer Model; Cell Line; Cell Lineage; Cells; Collection; Coupled; Development; Doxycycline; Genetically Engineered Mouse; Grant; Growth; Human; Immune; Large T Antigen; Maintenance; Malignant Epithelial Cell; Malignant Neoplasms; Merkel Cells; Merkel cell carcinoma; Messenger RNA; Mitotic; Modeling; Molecular; Mus; Neuroendocrine Cell; Neuroendocrine Tumors; Neurosecretory Systems; Pathogenesis; Phenotype; Play; Polyomavirus; Polyomavirus Transforming Antigens; Pre-Clinical Model; Production; Proliferating; Property; Resistance; Role; Skin; Skin Cancer; Small T Antigen; Suspensions; TP53 gene; Testing; Touch sensation; Transcript; Transplantation; Variant; Viral; Viral Oncogene; Virus; Work; base; cell type; cellular engineering; epidermal stem cell; experimental study; in vivo; insight; keratinocyte; knock-down; loss of function; mouse model; neoplastic cell; neuroendocrine phenotype; novel strategies; progenitor; stem cells; transcription factor; transcriptome; transgene expression; tumor; tumor progression; tumorigenesis; tumorigenic

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin cancer that frequently carries an integrated copy of Merkel cell polyomavirus (MCPyV) and expresses viral transforming antigens (TAgs) that likely play a key role in tumorigenesis. MCC tumor cells also express transcripts detected in normal, post- mitotic Merkel cells residing in skin, including a set of mRNAs encoding lineage-specific transcription factors implicated in neuroendocrine cell fate. Work from our lab and others established that MCPyV small T antigen (sTAg), +/- truncated large T antigen (tLTAg), is sufficient to drive transformation in vivo, but MCC-like tumors were not detected in any of these models despite TAg targeting to various potential tumor progenitor. The lack of a viable mouse model of MCC has been a major impediment to progress in this field. Normal Merkel cells arise from epidermal progenitors in specialized cellular compartments called touch domes, but the cell of origin of MCC is unknown. In an effort to override the apparent resistance of multiple cell types to MCPyV TAg-driven MCC development in genetically-engineered mice, we generated mice co- expressing the Merkel cell transcription factor Atoh1, together with MCPyV TAgs, in epidermal keratinocytes. These mice developed small collections of proliferating MCC-like tumor cells, and when coupled with deletion of one copy of p53, yielded gross tumors strikingly similar to human MCCs based on multiple criteria. Given the pivotal role of Atoh1 in MCC tumorigenesis we performed complementary loss-of-function studies, and discovered that Atoh1 knock-down converts human MCC cells from their typical neuroendocrine phenotype and growth in suspension, to cells with adherent growth, loss of neuroendocrine markers, and more aggressive behavior in vivo. We thus hypothesize that Atoh1 and other transcription factors governing Merkel cell fate play a pivotal role in MCC pathogenesis as well as maintenance of the neuroendocrine tumor phenotype. We propose the following aims to test this hypothesis. 1) Generate and characterize MCC-like tumors driven by MCPyV TAg expression targeted to candidate MCC progenitor cells. 2) Determine whether MCPyV TAg expression is required for mouse MCC maintenance. 3) Examine the role of Merkel cell lineage transcription factors in governing neuroendocrine cell fate and biological behavior of human MCC cell lines. These studies will yield new insights into the molecular basis of MCC and validate a much-needed mouse model of MCC.

默克尔细胞癌 (MCC) 是一种罕见的侵袭性神经内分泌皮肤癌，通常携带 默克尔细胞多瘤病毒 (MCPyV) 的整合副本并表达病毒转化抗原 (TAgs) 可能在肿瘤发生中发挥关键作用。 MCC 肿瘤细胞也表达在正常、术后检测中检测到的转录本。 存在于皮肤中的有丝分裂默克尔细胞，包括一组编码谱系特异性转录因子的 mRNA 与神经内分泌细胞的命运有关。我们实验室和其他人的工作证实 MCPyV 小 T 抗原 (sTAg)，+/-截短的大T抗原(tLTAg)，足以驱动体内转化，但类似于MCC 尽管TAg针对各种潜在的肿瘤祖细胞，但在这些模型中均未检测到肿瘤。 缺乏可行的 MCC 小鼠模型一直是该领域进展的主要障碍。 正常的默克尔细胞起源于称为触摸的特殊细胞区室中的表皮祖细胞 圆顶，但 MCC 的起源细胞未知。为了克服多个明显的阻力 细胞类型到 MCPyV Tag 驱动的基因工程小鼠 MCC 发育，我们生成了小鼠共同 在表皮角质形成细胞中表达默克尔细胞转录因子 Atoh1 以及 MCPyV TAgs。 这些小鼠产生了少量的增殖性 MCC 样肿瘤细胞，并且当与缺失相结合时 根据多项标准，p53 的一个拷贝产生了与人类 MCC 惊人相似的肉眼肿瘤。给定 Atoh1 在 MCC 肿瘤发生中的关键作用我们进行了补充功能丧失研究，并且 发现 Atoh1 敲低使人类 MCC 细胞从其典型的神经内分泌表型转变 和悬浮生长，细胞贴壁生长，神经内分泌标记物丢失，更具攻击性 体内行为。 因此，我们假设Atoh1和其他控制默克尔细胞命运的转录因子发挥着关键作用 MCC 发病机制以及神经内分泌肿瘤表型的维持。我们建议 以下旨在检验这一假设。 1) 生成并表征由 MCPyV TAg 驱动的 MCC 样肿瘤 针对候选 MCC 祖细胞的表达。 2) 判断MCPyV TAg表达是否为 鼠标 MCC 维护所需。 3) 检查默克尔细胞谱系转录因子在 控制人类 MCC 细胞系的神经内分泌细胞命运和生物学行为。这些研究将产生 对 MCC 分子基础的新见解并验证了急需的 MCC 小鼠模型。