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， 整合拷贝的默克尔细胞多瘤病毒（MCPyV），并表达病毒转化抗原（TAg）， 可能在肿瘤发生中起关键作用。MCC肿瘤细胞也表达在正常、移植后 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 与神经内分泌细胞命运有关。我们实验室和其他实验室的工作确定了MCPyV小T抗原 （sTAg），+/-截短的大T抗原（tLTAg），足以驱动体内转化，但MCC样抗原， 尽管TAg靶向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表皮祖细胞，它们位于称为触觉的特殊细胞区室中 圆屋顶，但MCC的起源细胞未知。在努力克服多个明显的阻力 细胞类型与基因工程小鼠中MCPyV TAg驱动的MCC发育，我们产生了小鼠共 在表皮角质形成细胞中表达默克尔细胞转录因子Atoh 1以及MCPyV标签。 这些小鼠产生了增殖的MCC样肿瘤细胞的小集合，当与缺失相结合时， 的一个拷贝的p53，产生的大体肿瘤惊人的相似，人类MCC基于多个标准。给定 Atoh 1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， 发现Atoh 1基因敲低可将人类MCC细胞从其典型的神经内分泌表型转化为 和悬浮生长，以贴壁生长的细胞，神经内分泌标志物的损失，更积极的 体内行为 因此，我们假设Atoh 1和其他调控默克尔细胞命运的转录因子在细胞凋亡中起着关键作用 MCC发病机制以及维持神经内分泌肿瘤表型。我们建议 下面我们来验证一下这个假设。1)生成并表征由MCPyV TAg驱动的MCC样肿瘤 靶向候选MCC祖细胞的表达。2)确定MCPyV TAg表达是否为 用于鼠标MCC维护。3)检查默克尔细胞谱系转录因子在 控制人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 新的见解MCC的分子基础，并验证了急需的MCC小鼠模型。