Identification of targetable pathways of prognostic relevance involved in the biology of atypical teratoid/rhabdoid tumors (AT/RT).

非典型畸胎瘤/横纹肌样瘤是一种主要影响幼儿的恶性脑肿瘤。尽管采取了积极的治疗方法，但AT/RT的预后仍然令人沮丧。导致SMARCB1或SMARCA4功能丧失的遗传改变是特征性的。这些基因是进化上高度保守的atp依赖性SWI/SNF染色质重塑复合体的成员，在细胞增殖和分化的表观遗传调控中起关键作用。然而，对于SMARCB1失活或SMARCA4失活所涉及的可靶向下游通路，我们知之甚少。因此，我们认为研究下游信号通路对于更好地理解AT/RT的分子发病机制至关重要。大部分AT/RT显示SMARCB1缺失。基于我们之前在smarcb1缺陷果蝇模型中的结果，我们将进一步研究已确定的候选基因在AT/RT生物学中的作用。具体来说，我们有兴趣了解为什么merlin、kibra和expanded基因的功能对于snr1 （SMARCB1的苍蝇同源物）敲低相关的表型至关重要。为此，我们将利用报告基因检测和基因表达谱研究黑腹果蝇的信号通路，并确认所鉴定的通路在人类smarcb1缺陷横纹肌样肿瘤细胞系中的作用。一些AT/RT显示SMARCB1功能保留，但遗传改变导致SMARCA4功能丧失。因此，我们还旨在确定与SMARCA4缺乏的有害影响有关的途径。为了实现这一目标，我们将利用brm敲除蝇建立SMARCA4缺陷蝇模型。使用修饰子筛选和超过1000个表达不同siRNA结构的果蝇菌株，我们将确定与brm敲低相关的表型相关的功能基因。通过探索siRNA沉默和药物抑制对肿瘤细胞增殖和迁移的影响，确定候选基因在人smarca4缺陷人横纹肌肿瘤细胞系中的功能作用。在确认了小鼠异种移植模型中已鉴定的基因和通路的重要性，以及通过欧洲横纹肌样肿瘤登记处EU-RHAB获得的人类AT/RT样本中它们的表达对预后和治疗反应的影响后，我们将能够为靶向治疗提供新的途径。从长远来看，我们的目标是为更好地治疗AT/RT儿童提供先决条件。我们的研究结果也可能有助于更好地治疗其他显示SMARCB1或SMARCA4功能丧失的肿瘤实体。

Atypical teratoid/rhabdoid tumors (AT/RT) are malignant brain tumors mainly affecting young children. Despite aggressive therapeutic approaches, the prognosis of AT/RT remains dismal. Genetic alterations resulting in functional loss of SMARCB1 or SMARCA4 are characteristic. These genes are members of the evolutionarily highly conserved ATP-dependent SWI/SNF chromatin remodeling complex, which plays a key role in the epigenetic regulation of cell proliferation and differentiation. Little is known, however, on targetable downstream pathways involved in the oncogenic effects of SMARCB1 inactivation or SMARCA4 inactivation. We thus assume that investigation of downstream signaling pathways is essential for a better understanding of the molecular pathogenesis of AT/RT. The majority of AT/RT shows SMARCB1 deficiency. Based on our previous results in a fly model of SMARCB1-deficiency, we will therefore further investigate the role of identified candidate genes in the biology of AT/RT. Specifically, we are interested to learn why the function of the genes merlin, kibra and expanded is essential for the phenotype associated with knockdown of snr1, the fly homolog of SMARCB1. To this end, we will investigate signaling pathways using reporter assays and gene expression profiling in Drosophila melanogaster and confirm the role of identified pathways in human SMARCB1-deficient rhabdoid tumor cell lines. Some AT/RT show retained SMARCB1 function, but genetic alterations causing functional loss of SMARCA4. We therefore also aim to identify pathways involved in the detrimental effects of SMARCA4 deficiency. To achieve this goal, we will establish a fly model of SMARCA4 deficiency using brm knockdown flies. Using a modifier screen and more than 1000 fly strains expressing various siRNA constructs, we will identify those genes functionally involved in the phenotype associated with brm knockdown. The functional role of identified candidate genes will be confirmed in human SMARCA4-deficient human rhabdoid tumor cell lines by exploring the effect of siRNA silencing and pharmacological inhibition on tumor cell proliferation and migration.After confirming the importance of identified genes and pathways in a mouse xenograft model as well as examining the consequences of their expression on prognosis and therapy response in human AT/RT samples obtained through the European Rhabdoid Tumor Registry EU-RHAB, we will be able to provide novel avenues for targeted therapies. In the long-term, our goal is to provide the prerequisites for a better treatment of children with AT/RT. Our results might also contribute to better treatment of other tumor entities showing functional loss of SMARCB1 or SMARCA4.