Genetics of Rhabdomyosarcoma

描述(申请人提供)：肿瘤细胞的一个亚群具有独特的自我更新能力，并对复发负责。揭示控制自我更新的细胞类型和机制将是设计癌症治疗新疗法的当务之急。这项应用的重点是揭示胚胎横纹肌肉瘤(ERMS)-一种毁灭性的儿童肌肉癌-参与癌细胞自我更新的机制。在开发了一个强大的斑马鱼ERMS模型，准确地概括了这种疾病的分子基础，并鉴定了表达myf5的癌症启动细胞后，这里概述的实验将揭示自我更新的基本生物学，并确定MYF5是否是肿瘤生长和自我更新所必需的。我们假设ERMS是获得与MYF5基因程序相关的自我更新潜能的结果。目标1的目标将是观察胚胎横纹肌肉瘤的自我更新。利用共聚焦成像和在肌肉发育的不同阶段表达荧光蛋白的转基因报告系，我们现在有了前所未有的、不受限制的途径来可视化内源性利基中的肿瘤启动细胞。这样的实验从未在任何癌症模型中被描述过。Aim 1中概述的实验将确定自我更新是否仅限于与肿瘤生长相关的特定肿瘤区位，在不同的肿瘤发生阶段，自我更新癌细胞中发生不对称和对称细胞分裂的程度，以及ERMS细胞是否可以从更成熟的细胞群去分化为自我更新的myf5+肿瘤启动细胞。这些实验利用斑马鱼模型系统的独特属性，通过延时共聚焦和双光子成像直接显示体内的癌症过程。目标2将确定MYF5是否调节斑马鱼和人类ERM的自我更新潜力。微阵列表达谱显示，与肺泡型RMS和正常肌肉相比，MYF5在人类ERMS中高表达，表明MYF5+细胞在这一亚型疾病中丰富。使用斑马鱼ERMS癌症模型结合人类细胞培养实验，我们将评估MYF5是否是肿瘤生长和自我更新所必需的。同样，我们还将评估MYF5是否是癌基因，是否可以将细胞锁定在易于发生ERMS的自我更新的细胞状态中。总之，这项申请提供了一个全面的计划，以审问ERMS的自我更新，这项工作的长期目标是确定与自我更新和攻击性相关的分子途径，最终导致确定治疗ERMS的药物靶点。 公共卫生相关性：发现与自我更新相关的分子途径将为合理设计治疗癌症的药物提供新的药物靶点。我们的应用重点是确定胚胎横纹肌肉瘤自我更新的基本原理以及MYF5在控制这一过程中所起的作用。

DESCRIPTION (provided by applicant): A subset of tumor cells have the unique ability to self-renew and are responsible for relapse. Uncovering the cell types and mechanisms that govern self-renewal will be imperative for designing new therapies in the treatment of cancer. The focus of this application is to uncover the mechanisms involved in cancer cell self-renewal in embryonal rhabdomyosarcoma (ERMS) - a devastating pediatric cancer of muscle. Having developed a robust model of zebrafish ERMS that accurately recapitulates the molecular underpinnings of this disease and identified the myf5-expressing cancer-initiating cell, experiments outlined here will uncover the basic biology of self-renewal and determine if MYF5 is required for tumor growth and self-renewal. We hypothesize that ERMS results from acquisition of self- renewal potential that is associated with the MYF5 gene program. The goal of aim 1 will be to visualize self-renewal in embryonal rhabdomyosarcoma. Using confocal imaging and transgenic reporter lines that express fluorescent proteins in various stages of muscle development, we now have unprecedented and unfettered access to visualize tumor-initiating cells in their endogenous niche. Such experiments have never been described in any model of cancer. Experiments outlined in aim 1 will determine if self-renewal is confined to specific tumor niches associated with tumor growth, the extent to which asymmetric and symmetric cell division occurs in self-renewing cancer cells at various stables of tumorigenesis, and if ERMS cells can de-differentiate from more mature cell populations into self-renewing myf5+ tumor-initiating cells. These experiments capitalize on the unique attributes of the zebrafish model system to directly visualize cancer processes in vivo by time- lapse confocal and 2-photon imaging. Aim 2 will determine if MYF5 regulates self-renewal potential in both zebrafish and human ERMS. Microarray expression profiling shows that MYF5 is highly expressed in human ERMS when compared to alveolar RMS and normal muscle, suggesting that MYF5+ cells are abundant in this subtype of disease. Using the zebrafish ERMS cancer model in conjunction with human cell culture experiments, we will assess if MYF5 is required for tumor growth and self-renewal. Similarly, we will also assess if MYF5 is an oncogene and can lock cells in a self-renewing cell state that predisposes to ERMS. In total, this application provides a comprehensive plan to interrogate self-renewal in ERMS with the long-term goal of this work to identify molecular pathways associated with self- renewal and aggression, ultimately leading to the identification of drug targets for the treatment of ERMS. PUBLIC HEALTH RELEVANCE: Uncovering molecular pathways associated with self-renewal will provide new drug targets for rational drug design for the treatment of cancer. Our application centers on determining the basic tenets of self-renewal in embryonal rhabdomyosarcoma and the role that MYF5 elicits in controlling this process.