Uncovering the Origin and Growth Regulation of Melanocytic Nevi

揭示黑素细胞痣的起源和生长调节

• 批准号: 10013693
• 负责人: Anand K Ganesan
• 金额: $ 47.84万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-24 至 2021-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10013693
• 关键词: Animals; Archives; BRAF gene; Benign; Benign Melanocytic Nevus; Cell Cycle; Cells; Collection; Evolution; Excision; Feedback; Gene Expression Profiling; Genetically Engineered Mouse; Genomics; Growth; Human; Image; Immune system; In Situ Hybridization; Lead; LoxP-flanked allele; Malignant - descriptor; Mediating; Melanins; Melanocytic nevus; Modeling; Mole the mammal; Morphology; Mus; Mutation; Nature; Neurons; Nevi and Melanomas; Nevus; Nevus Cell; Oncogenes; Oncogenic; Pigments; Population; Regulation; Secondary to; Signal Transduction; Skin; Stem cells; Testing; Time; Transgenic Mice; Work; cytokine; density; human tissue; imaging approach; in vivo; inhibitor/antagonist; insight; life history; macrophage; melanocyte; melanoma; microscopic imaging; molecular marker; mouse model; multiphoton microscopy; mutant; nerve stem cell; novel; overexpression; receptor; recruit; response; senescence; single cell sequencing; single-cell RNA sequencing; stem-like cell; ultraviolet irradiation

SUMMARY Melanocytic nevi are benign growths of melanocytes that initiate spontaneously, reach a fixed size, and eventually regress. While most nevi are benign, they can be difficult to distinguish from melanoma, leading to the unnecessary excision of many normal nevi. Conventional wisdom suggests that nevi arrest their growth by a mechanism called “oncogene-induced senescence”- nevi initiate when melanocytes acquire a BRAF mutation, this clonal population of melanocytes replicate for a fixed number of cell cycles, and eventually nevi just stop growing. All cells in nevi, however, cannot be truly senescent; nevi can regrow after partial excision, can be induced to grow with UV irradiation, and some nevi can even evolve into melanoma. Little is known about how this growth arrest is achieved in vivo. We recently used a combination of multiphoton microscopy (MPM) imaging and single cell sequencing to better understand the evolution of BRAF mutant melanocytic nevi in mouse skin. These studies revealed that nevi are composed of two populations of melanocytes: a population with less pigment that expresses stem cell markers (nevus-initiating cells-NI), and a well- differentiated population of melanocytes full of melanin (nevus arrested cells-NA). Single cell gene expression analysis revealed that NI cells expressed Wnt receptors/ Wnt downstream targets while NA cells expressed secreted Wnt inhibitors, identifying a feedback loop that could restrict nevus growth. The stem cell like population also expressed cytokines that recruit macrophages, and large numbers of infiltrating macrophages were observed in nevus skin. These observations led us to hypothesize that nevi develop from a NI cells that: 1) generates pigmented progeny that then restricts their growth; 2) recruits macrophages that ultimately facilitate nevus regression. In this proposal, we use a combination of single cell genomics, live imaging, genetically engineered mouse models, and archived human tissues to: 1) determine whether nevi initiate from a nevus initiating cell that expresses stem cell markers; 2) test whether nevi arrest their growth secondary to a Wnt inhibitor feedback loop that restricts the growth of the nevus initiating cell population; 3) test whether nevi regress secondary to infiltrating macrophages. Completion of these studies will not only lead to a better understanding of the origin and evolution of melanocytic nevi, but also define a set of molecular markers that can be used to identify those nevi with malignant potential that need to be removed.

摘要 黑色素细胞痣是黑素细胞的良性生长，自发开始，达到固定大小，并且 最终会倒退。虽然大多数痣是良性的，但它们很难与黑色素瘤区分开来，导致 对许多正常痣进行不必要的切除。传统智慧认为，nevi通过以下方式阻止它们的生长 当黑素细胞获得BRAF时，一种称为癌基因诱导衰老的机制-nevi启动 突变，这种黑素细胞的克隆性群体复制固定数量的细胞周期，最终形成色素痣。 别再长了。然而，痣中的所有细胞都不可能真正衰老；痣在部分切除后可以再生， 可在紫外线照射下诱导生长，一些痣甚至可演变为黑色素瘤。鲜为人知 关于这种生长停滞是如何在体内实现的。我们最近使用了多光子显微镜的组合 MPM成像和单细胞测序更好地了解BRAF突变型黑色素细胞痣的演变 在老鼠的皮肤里。这些研究表明，色素痣由两组黑素细胞组成：a 表达干细胞标记物的色素较少的群体(痣启动细胞-NI)，以及 分化的充满黑色素的黑素细胞群(雀斑抑制细胞-NA)。单细胞基因表达 分析表明，NI细胞表达Wnt受体/Wnt下游靶点，而NA细胞表达 分泌Wnt抑制物，识别可能限制雀斑生长的反馈回路。干细胞就像 人群还表达了募集巨噬细胞的细胞因子，以及大量浸润性巨噬细胞 在雀斑皮肤中观察到。这些观察结果使我们假设nevi是从ni细胞发展而来的。 这：1)产生色素沉着的后代，然后限制它们的生长；2)招募巨噬细胞， 最终促进雀斑的消退。在这项提案中，我们使用了单细胞基因组学的组合，LIVE 成像、基因工程小鼠模型和存档的人体组织：1)确定雀斑是否 从表达干细胞标记物的雀斑启动细胞启动；2)测试雀斑是否阻止它们的生长 次级于Wnt抑制物反馈环，该反馈环限制了痣起始细胞群的生长；3) 检测色素痣是否继发于浸润性巨噬细胞。这些研究的完成不仅将 有助于更好地了解黑色素细胞痣的起源和进化，也定义了一套分子 可用于识别那些具有恶性潜在性且需要移除的痣的标志物。