Medulloblastoma and Metastases

描述(申请人提供)：脑瘤是最常见的实体恶性肿瘤，也是儿童癌症相关死亡的主要原因。髓母细胞瘤(MB)是儿童最常见的脑肿瘤。MB的传播(转移)通过脑脊液播撒覆盖大脑和脊髓的软脑膜。MB的转移是难于治疗的，基本上定义为患有无法治愈的肿瘤的儿童。我们在由Sonic Hedgehog(Shh)信号驱动的MB基因工程小鼠模型中动员了转座元件睡美人(SB)，并观察到了强劲的转移。对匹配的原发灶和转移灶的遗传分析表明，肿瘤经历了平行进化，并含有由转位产生的独特的、克隆选择的突变。这是首批能够识别驱动转移的基因的小鼠模型之一。我们假设SB可以发现克隆组织和潜在的进展/转移基因，这些数据将告知人类MB。我们建议对来自MB患者的原发瘤和转移瘤进行配对实验。我们还提出了额外的基于SB的实验，以确定一个新的MYCN驱动的MB模型中的转移基因，该模型在很大程度上独立于Shh信号，并同时模拟了经典的(60%的人类MB)和大细胞、间变性病理(10%的人类MB)。由于经典的人类MB既可以由myc驱动，也可以由p53缺失驱动，我们也将在p53缺陷小鼠中动员SB。3个模型的使用最大限度地减少了背景对生物的影响，表征了甲基溴的广泛遗传子集，并便于识别和确定优先顺序：1)。在3种不同的MB模型中，驱动转移的基因。2)。候选人转移了人类MB中改变的基因。3)。潜在的治疗靶点。这些数据对治疗有着深远的影响，因为治疗假设转移瘤在生物学上与原发肿瘤相似。A.1.从两种模型中匹配的原发/转移的GEM MB中恢复转座子插入位点序列，以确定MB发病的重要基因和途径。A2.验证通过SB插入确定的候选转移基因的功能重要性。A.3.利用人类基因组数据以及来自人类MB的成对肿瘤和转移，评估对软脑膜扩散很重要的层次结构、基因和途径。 公共卫生相关性：髓母细胞瘤(MB)是一种常见且经常致命的儿童肿瘤，目前的治疗方法往往无效。MB通过脑脊液局部传播(转移)基本上定义为不治之症。我们的长期目标是在三种不同的MB基因工程小鼠模型中动员转座元件睡美人(SB)，以剖析恶性进展和软脑膜转移的克隆组织和遗传基础，为人类MB提供信息。这项提案的成功完成确定了转移性MB儿童的转移基因和新的治疗目标。

DESCRIPTION (provided by applicant): Brain tumors are the most common solid malignancies and the leading cause of cancer- related death in children. Medulloblastoma (MB) is the most common pediatric brain tumor. Dissemination (metastasis) of MB through the cerebrospinal fluid seeds the leptomeningeal membranes that cover the brain and spinal cord. Metastases in MB are refractory to treatment, essentially defining children with incurable tumor. We mobilized the transposable element Sleeping Beauty (SB) in a genetically engineered mouse model of MB driven by Sonic Hedgehog (Shh) signaling and observed robust metastases. Genetic analyses of matched primary and metastatic lesions indicate that tumors undergo parallel evolution and harbor distinct, clonally selected mutations generated by transposition. This is among the first mouse models enabling identification of genes driving metastases. We hypothesize that SB can uncover clonal organization and genes underlying progression/metastasis, and that these data will inform human MB. We propose experiments characterizing paired primary and metastatic tumors from patients with MB. We also propose additional SB based experiments to identify metastases genes in a novel MYCN-driven model for MB which arises largely independently of Shh signaling and which models both classic (60% of human MB) and large cell, anaplastic pathologies (10% of human MB). Because classic human MB can be driven either by myc or by loss of p53, we will also mobilize SB in p53 deficient mice. The use of 3 models minimizes biological effects due to background, characterizes a broad genetic subset of MB, and facilitates identification and prioritization of: 1). Genes driving metastases in 3 distinct models for MB. 2). Candidates metastases genes altered in human MB. 3). Potential therapeutic targets. These data have profound implications for therapy, which assumes that metastases are biologically similar to the primary tumor. A.1.To recover transposon insertion site sequences from matched primary/metastatic GEM MB in two models in order to identify genes and pathways important for MB pathogenesis. A.2.To validate the functional importance of candidate metastases genes identified by SB insertion. A.3.To evaluate hierarchical structures, genes and pathways important for leptomeningeal dispersion using human genomic data, and paired tumors and metastases from human MB. PUBLIC HEALTH RELEVANCE: Medulloblastoma (MB) is a common and frequently lethal tumor of children, for which current therapies are often ineffective. Locoregional dissemination (metastasis) of MB through the cerebrospinal fluid essentially defines incurable MB. Our long term objective is to mobilize the transposable element Sleeping Beauty (SB) in three different genetically engineered mouse models of MB to dissect the clonal organization and genetic bases of malignant progression and leptomeningeal metastasis, to inform human MB. Successful completion of this proposal identifies metastases genes and new therapeutic targets for children with metastatic MB.