Modifiers of Tumor Susceptibility in Murine Neuroblastoma

神经母细胞瘤是一种起源于周围神经脊部的肿瘤，是一种常见的儿童致命性肿瘤，转录因子MYCN的扩增在该肿瘤中频繁发生，并与晚期 疾病。我们在酪氨酸羟基酶(TH)启动子的控制下，通过将MYCN转基因基因的表达引导到周围神经脊，产生了高危神经母细胞瘤的转基因小鼠模型。 遗传学分析证实了人类和小鼠肿瘤之间保守的遗传变化，并认为转基因TH-MYCN的小鼠代表了儿童神经母细胞瘤的重要遗传模型。我们假设，导致小鼠神经母细胞瘤形成的额外遗传和表观遗传损伤将与儿童神经母细胞瘤相关的基因有关。这项应用的长期目标是确定小鼠和人类神经母细胞瘤的遗传和表观遗传学变化。这项研究中发现的基因可能揭示与人类MYCN扩增的神经母细胞瘤相关的新机制和途径，最终导致新的治疗靶点。不同品系的小鼠对肿瘤的易感性不同。转TH-MYCN基因的FVB/N品系小鼠未发生肿瘤，129/SVJ品系转基因小鼠几乎全部在4月龄前死于肿瘤，129/SVJ FVB/N品系F1小鼠外显率为4%。这些观察表明，生殖系修饰基因的结构或表观遗传变化在不同菌株之间是不同的，与Mycn相互作用，并奠定了不同菌株之间敏感性差异的基础。这些菌株特异性的差异为鉴定在鼠和人神经母细胞瘤中都重要的继发遗传和表观遗传事件提供了重要的资源。我们建议动员一种强大的插入诱变剂，脊椎动物睡美人(SB)转座子，并将体细胞插入突变与比较基因组杂交和修饰遗传学相结合，以确定影响小鼠神经母细胞瘤肿瘤易感性的基因。目的1利用SB转座子为基础的插入突变来加速F1小鼠的致癌突变和增加肿瘤的穿透性。目标2应用基于数组的比较 基因组杂交以表征F1小鼠自发和转座子诱导的肿瘤中的拷贝数异常，表征品系特有的甲基化模式，并识别肿瘤中的表观遗传学变化。Aim 3在体外验证和表征候选基因 在体内，根据人类神经母细胞瘤中特定候选基因的参与情况进行优先排序。

Neuroblastoma, a tumor of peripheral neural crest origin, is a common and lethal tumor of childhood.Amplification of the transcription factor MYCN occurs frequently in this tumor, and correlates with advanced disease. We generated a transgenic mouse model for high-risk neuroblastoma by directing expression of a MYCN transgene to the peripheral neural crest, under control of the Tyrosine Hydroxylase (TH) promoter. Genetic analyses identified conserved genetic changes between human and murine tumors, and argue that mice transgenic for TH-MYCN represent an important genetic model for childhood neuroblastoma. We hypothesize that the additional genetic and epigenetic lesions which contribute to neuroblastoma formation in the mouse will be in genes relevant to neuroblastoma in children. The long term objective of this application is to identify genetic and epigenetic changes in murine and human neuroblastoma. Genes identified in this study may reveal novel mechanisms and pathways relevant to human MYCN-amplified neuroblastoma, ultimately leading to novel therapeutic targets. Strains of mice differ in susceptibility to tumors. Mice transgenic for TH-MYCN in strain FVB/N do not develop tumors, nearly all transgenic mice in strain 129/SvJ die of tumors by 4 months of age, and 129/SvJ FVB/N F1 mice show 4% penetrance. These observations suggest that structural or epigenetic changes in germ line modifier genes differ between strains, interact with Mycn, and underlie the differences in susceptibility between strains. These strain-specific differences provide a critical resource to identify secondary genetic and epigenetic events important in both murine and human neuroblastoma. We propose to mobilize a powerful insertional mutagen, the vertebrate Sleeping Beauty (SB) transposon, and to combine use of somatic insertional mutagenesis with comparative genomic hybridization and modifier genetics to identify genes that influence susceptibility to tumors in murine neuroblastoma. Aim 1 uses SB transposon-based insertional mutagenesis to accelerate oncogenic mutations and to increase penetrance of tumors in F1 mice. Aim 2 applies array-based comparative genomic hybridization to characterize copy-number abnormalities in both spontaneous and transposon-induced tumors in F1 mice, to characterize strain-specific methylation patterns, and to identify epigenetic changes in tumors. Aim 3 validates and characterizes candidate genes in-vitro and in-vivo, prioritizing based on the involvement of specific candidate genes in human neuroblastoma.