Epigenetic Effect of the Microenvironment on Stem Cell Plasticity and Function

干细胞与其微环境之间存在着一种动态的、复杂的关系，这在 在细胞命运决定中的作用。确定干细胞可塑性的分子机制的关键是 理解微环境对细胞表型产生的独特表观遗传作用。 我们实验室以前的研究发现，转移性人类黑色素瘤 细胞表达多种细胞表型及其各自的前体细胞，提示去分化 具有干细胞表型特征的癌细胞。支持这一概念的其他证据 肿瘤细胞可塑性包括：人转移性黑色素瘤细胞形成血管生成 具有同时表达内皮特异性基因的网络；发展嵌合体血液 小鼠肢体缺血模型中的血管；以及启动斑马鱼胚胎组织的形成 模特。此外，最近的初步发现表明转移性黑色素瘤的强大影响。 诱导正常黑素细胞转分化为侵袭性黑素细胞的微环境 当暴露在这种转移环境中时，肿瘤细胞表型。最有趣的是，初步发现 人胚胎干细胞(HESCs)在转移性微环境中的分化 向高度迁移的表型转变；而与hESCs相关的微环境则恢复为无性贫血 转移性黑色素瘤细胞向黑素细胞样表型转化，并伴有色素沉着。因此，基于这些 耐人寻味的观察是，我们建议检验中心假设，即微环境与 干细胞--人类胚胎干细胞的代表。癌症干细胞和正常的表皮干细胞--包含 有可能对细胞的表观遗传学和表型进行重新编程的信息线索 暴露在它身上。使用唯一的。3-D器官模型和斑马鱼胚胎，以及功能 分析、成像、激光显微解剖。和全球基因分析，我们建议：目标1：确定 与肿瘤干细胞hESCs相关的三维微环境的表观遗传效应比较 (主要是黑色素瘤)和正常的表皮干细胞，以了解它们重新编程基因和 特定干细胞群体的表型。目标2：确定表观遗传学的分子基础 不同3-D暴露对受影响干细胞群体的基因和表型的重新编程 微环境。目的3：研究胚胎、肿瘤和正常组织的发育可塑性 斑马鱼胚胎模型中的表皮干细胞--确定关键的生物学相关性 参与控制细胞表型和细胞命运决定的调控通路。在 这些研究的完成，我们期望对归纳性质的差异有新的见解。 这些干细胞各自的微环境(S)可以被翻译成新的治疗靶点。

A dynamic, complex relationship exists between stem cells and their microenvironment, which plays a pivotal role in cell fate determination. Key to identifying the molecular mechanisms underlying stem cell plasticity, is understanding the unique epigenetic role of the microenvironment on the emergence of cell phenotype. Previous studies from our laboratory have revealed the unexpected finding that metastatic human melanoma cells express multiple cellular phenotypes and their respective precursor cells, suggesting a dedifferentiated cancer cell with a phenotype characteristic of stem cells. Additional evidence supporting the concept of tumor cell plasticity includes: the demonstration of human metastatic melanoma cells forming vasculogenic- like networks with the simultaneous expression of endothelial-specific genes; developing chimeric blood vessels in an ischemic mouse limb model; and initiating the formation of tissues in an embryonic zebrafish model. Furthermore, recent preliminary findings indicate the powerful influence of a metastatic melanoma microenvironment with respect to inducing transdifferentiation of normal melanocytes into an aggressive tumor cell phenotype ~ when exposed to this metastatic milieu. Most interestingly, preliminary findings with human embryonic stem cells (hESCs) exposed to a metastatic microenvironment reveal their differentiation to a highly migratory phenotype; while the microenvironment associated with hESCs reverts amelanotic metastatic melanoma cells to a melanocyte-like phenotype with pigmentation. Therefore, based on these intriguing observations, we propose to test the central hypothesis that the microenvironment associated with stem cells -- representative of hESCs. cancer stem cells, and normal epidermal stem cells -- contains informational cues with the potential to epigeneticallv reprogram the genotype and phenotype of cells exposed to it. Using unique. 3-D organotypic models and zebrafish embryos, together with functional analysis, imaging, laser microdissection. and global gene analysis, we propose to: Aim 1: Determine the comparative epigenetic effects of the 3-D microenvironments associated with hESCs, cancer stem cells (primarily melanoma), and normal epidermal stem cells for their potential to reprogram the genotype and phenotype of specific stem cell populations. Aim 2: Identify the molecular basis for the epigenetic reprogramming of the genotype and phenotype of the affected stem cell populations exposed to various 3-D microenvironments. Aim 3: Investigate the developmental plasticity of the embryonic, cancer and normal epidermal stem cells in an embryonic zebrafish model - to determine the biological relevance of key regulatory pathways involved in the control of cellular phenotype and cell fate determinations. At the completion of these studies, we expect to gain novel insights into the differences in inductive properties of the respective microenvironment(s) of these stem cells that could be translated for novel therapeutic targets.