The role of HOXD13 in controlling Ewing sarcoma cell plasticity and metastasis

项目摘要 尤文肉瘤是一种侵袭性骨肿瘤，在儿童和青少年中发病率最高。系统性 化疗和局部控制措施提高了局部肿瘤患者的生存率 然而，患有转移性疾病的患者的存活率是令人沮丧的。尤文肉瘤的定义是肿瘤- 启动EWS-ETS融合蛋白，最常见的是EWS-FLI 1，它们仍然是不可药用的，突出了 需要新的策略和治疗机会来提高患者生存率。 EWS-ETS融合蛋白通过增强子劫持基因调控网络诱导恶性转化 重新编程假定的起源细胞是来源于神经嵴的间充质干/祖细胞 或中胚层谱系。除了EWS-FLI 1融合蛋白，尤文肉瘤肿瘤很少与其他肿瘤一起出现。 复发性突变，但存在临床异质性。肿瘤异质性已经成为一个重要的 癌症研究中的概念，用于研究转移和治疗反应。其他儿科肿瘤研究 已经证明肿瘤细胞的表观遗传和转录组状态及其固有的可塑性反映了 生物学表型的差异，这是转移性进展所必需的。 发育程序的异常表达和调节是明显的，并可以部分解释 尤因瘤的未分化特征。同源异型盒（HOX）基因是进化上保守的转录因子 在身体形成和胚胎发生中起重要作用的因素。我们已经证明，后HOXD 基因表达在尤文肉瘤中广泛失调。特别是，我们的研究结果显示HOXD 13是 相对于正常和其他恶性组织在肿瘤样品中过表达，并且对于尤文肉瘤至关重要 致瘤性 我的初步数据显示HOXD 13表达通过EWS-FLI 1依赖性增强子维持 HOXD 13的重编程和调节导致神经和间充质谱系的相反转变 程序，支持HOXD 13作为细胞状态决定因素的作用。工作假设是HOXD 13 调节尤文肉瘤细胞的表观基因组和转录组转变，这些分子转变 驱动更多增殖性和转移性细胞状态之间的表型转变。这一假设将得到检验 两个目标。在目标1中，我将确定HOXD 13是否以及如何调节尤文肉瘤细胞状态。目标2将定义 尤文瘤细胞状态对转移表型的贡献。细胞状态的功能表征 转变，以及这些转变背后的机制，将产生新的见解尤因生物学 肉瘤转移，并为治疗的发展提供新的机会。

Project Summary Ewing sarcoma is an aggressive bone tumor that has a peak incidence in children and adolescents. Systemic chemotherapy and local control measures have improved survival rates for patients with localized tumors however, survival rates for patients with metastatic disease are dismal. Ewing sarcoma is defined by tumor- initiating EWS-ETS fusion proteins, most commonly EWS-FLI1, that have remained undruggable, highlighting a need for new strategies and therapeutic opportunities to improve patient survival. EWS-ETS fusions induce malignant transformation by hijacking gene regulatory networks via enhancer reprogramming. The putative cell of origin is a mesenchymal stem/progenitor cell derived from the neural crest or mesoderm lineage. Aside from EWS-FLI1 fusion proteins, Ewing sarcoma tumors rarely present with other recurrent mutations, however present with clinical heterogeneity. Tumor heterogeneity has become an important concept in cancer research for studying metastasis and treatment response. Studies of other pediatric tumors have demonstrated that the epigenetic and transcriptomic state of tumor cells and their inherent plasticity reflects differences in biologic phenotypes, of which are required for metastatic progression. Abnormal expression and regulation of developmental programs is evident and may in part explain the undifferentiated features of Ewing tumors. Homeobox (HOX) genes are evolutionarily conserved transcription factors that play essential roles in body patterning and embryogenesis. We have shown that posterior HOXD gene expression is widely deregulated in Ewing sarcoma. In particular, our findings revealed HOXD13 to be overexpressed in tumor samples relative to normal and other malignant tissues and critical for Ewing sarcoma tumorigenicity. My preliminary data reveal HOXD13 expression is maintained through EWS-FLI1-dependent enhancer reprogramming and modulation of HOXD13 leads to opposing shifts in neural and mesenchymal lineage programs, supporting the role of HOXD13 as a determinant of cell state. The working hypothesis is that HOXD13 regulates epigenomic and transcriptomic transitions in Ewing sarcoma cells and that these molecular transitions drive phenotypic transitions between more proliferative and metastatic cell states. This hypothesis will be tested in two aims. In Aim 1, I will determine if and how HOXD13 regulates Ewing sarcoma cell state. Aim 2 will define the contribution of Ewing tumor cell state to the metastatic phenotype. Functional characterization of cell state transitions, and the mechanisms underlying these transitions, will generate new insights into the biology of Ewing sarcoma metastasis and provide novel opportunities for the development of therapies.