Medulloblastoma and Metastases

描述（由申请人提供）：脑肿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）是最常见的小儿脑肿瘤。MB通过脑脊液的扩散（转移）在覆盖脑和脊髓的软脑膜上播种。MB中的转移对治疗是难治的，基本上定义为患有不可治愈的肿瘤的儿童。我们在由Sonic Hedgehog（Shh）信号传导驱动的MB基因工程小鼠模型中动员转座因子睡美人（SB），并观察到稳健的转移。匹配的原发性和转移性病变的遗传分析表明，肿瘤经历平行的演变和港口独特的，克隆选择的突变产生的转座。这是第一个能够识别驱动转移的基因的小鼠模型。我们假设SB可以揭示克隆组织和基因的进展/转移，这些数据将告知人类MB。我们提出的实验表征配对的原发性和转移性肿瘤患者MB。我们还提出了额外的SB为基础的实验，以确定转移基因在一个新的MYCN驱动的模型MB产生很大程度上独立于Shh信号，并模型经典（60%的人MB）和大细胞，间变性病理（10%的人MB）。因为经典的人MB可以由myc或p53缺失驱动，我们也将动员p53缺陷小鼠中的SB。使用3种模型最大限度地减少了背景造成的生物效应，表征了广泛的甲基溴遗传子集，并有助于识别和优先考虑：1）。在MB的3种不同模型中驱动转移的基因。2）。人MB中改变的候选转移基因。3）。潜在的治疗靶点。这些数据对治疗具有深远的意义，治疗假设转移与原发性肿瘤在生物学上相似。A.1.在两种模型中从匹配的原发性/转移性GEM MB中回收转座子插入位点序列，以鉴定对MB发病机制重要的基因和途径。A.2.验证通过SB插入鉴定的候选转移基因的功能重要性。A.3.使用人类基因组数据以及配对肿瘤和人类MB转移，评价对软脑膜扩散重要的分级结构、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，目前的治疗方法通常无效。MB通过脑脊液的局部扩散（转移）基本上定义了不可治愈的MB。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因子睡美人（SB），以剖析恶性进展和软脑膜转移的克隆组织和遗传基础，从而为人类MB提供信息。该提案的成功完成确定了转移基因和转移性MB儿童的新治疗靶点。

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.