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.

总结 黑素细胞痣是黑素细胞的良性生长，自发启动，达到固定大小， 最终回归。虽然大多数痣是良性的，但它们很难与黑色素瘤区分开来， 许多正常痣的不必要切除。传统观点认为，痣通过以下方式抑制其生长： 当黑素细胞获得BRAF时， 突变后，黑素细胞的克隆群体复制固定数量的细胞周期，最终形成痣。 停止生长然而，痣中的所有细胞并不是真正衰老的;痣在部分切除后可以再生， 紫外线照射可以诱导痣生长，有些痣甚至可以演变成黑色素瘤。知之甚少 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 (MPM)成像和单细胞测序，以更好地了解BRAF突变黑素细胞痣的演变 在老鼠皮肤上。这些研究表明，痣是由两个群体的黑素细胞： 表达干细胞标志物的色素较少的群体（痣起始细胞-NI），以及良好的 充满黑色素的黑色素细胞的分化群体（痣停滞细胞-NA）。单细胞基因表达 分析显示NI细胞表达Wnt受体/ Wnt下游靶点，而NA细胞表达Wnt受体/ Wnt下游靶点。 分泌的Wnt抑制剂，确定了一个反馈回路，可以限制痣的生长。干细胞 群体还表达招募巨噬细胞的细胞因子，以及大量浸润的巨噬细胞。 在痣皮肤中观察到。这些观察使我们假设痣是从NI细胞发展而来的 1）产生色素后代，然后限制其生长; 2）招募巨噬细胞， 最终促进痣消退。在这个建议中，我们使用单细胞基因组学，活 成像、基因工程小鼠模型和存档的人体组织，以：1）确定痣是否 从表达干细胞标记痣起始细胞起始; 2）测试痣是否阻止其生长 继发于限制痣起始细胞群生长的Wnt抑制剂反馈环; 3） 测试痣是否消退继发于浸润的巨噬细胞。完成这些研究不仅将 有助于更好地了解黑素细胞痣的起源和演变，也有助于确定一组分子生物学机制。 这些标记物可用于识别需要切除的具有恶性潜能的痣。