Druggable Genetic Lesions in Pediatric Astrocytoma

我们和其他人最近发现，激活丝氨酸/苏氨酸激酶BRAF的突变可能是 在所有儿童低级别星形细胞瘤(LGA)中发现多达一半。这些计划的首要目标是 研究的目的是确定突变的BRAF在这些肿瘤中的作用，并确定驱动这些肿瘤的其他突变 儿童低级别和高级别星形细胞瘤的形成。具体来说，我们建议： 目的一：使用新的“石蜡友好”基因组技术来鉴定肺癌的致癌基因突变 儿童星形细胞瘤。审问甲醛固定、石蜡包埋的档案组织的能力 将这些少见的儿科肿瘤的可用样本集扩大了十倍或更多 新鲜的冷冻肿瘤收藏品。我们将使用这些技术来治疗一组独特的1000多个存档肿瘤 样本以解决该领域中两个重要的悬而未决的问题。具体地说，(I)经常性开支是多少？ 缺乏BRAF突变的儿童星形细胞瘤的突变或扩增？和(Ii)什么是 与BRAF突变共存的突变？ 目标二：使用功能方法识别与激活的BRAF协同作用的突变 儿童星形细胞瘤。与在BRAF突变黑色素瘤中发现的类似，我们预计 在儿童星形细胞瘤中，其他突变与突变的BRAF协同作用。我们将同时使用候选项和 通过转化神经前体细胞来识别这种突变的无偏见的方法。 目标三：确定在BRAF上下游发挥作用的“可下药”信号发生器 N个转化的神经前体细胞。随着时间的推移，可以使用BRAF的小分子抑制剂。 用于治疗BRAF突变的儿科LGA。然而，多种蛋白激酶已被证明是 在高级别成人胶质瘤中共激活，在突变的BRAF转化中也可能是这种情况 儿童星形细胞瘤。在这个目标中，我们将进行全基因组范围的基因筛选，寻找能够 替代激活的BRAF，以失调正常神经前体细胞的增殖。这 信息将有助于定义可能导致缺乏BRAF突变的儿童星形细胞瘤的基因以及 明确了抵抗BRAF抑制的潜在机制。 这三个具体目标都得到了创新的神经病理学核心和共享的支持 项目二和项目三的技术和试剂。 相关性(请参阅说明)： 许多儿童脑肿瘤最初可以通过手术、化疗和/或放射治疗来治疗。然而， 这些治疗对成长中的儿童的临床副作用可能是显著的。而且，这些肿瘤 经常复发，并最终对标准治疗方案无效。因此，迫切需要 对这些肿瘤进行靶向治疗。该项目将确定和描述有希望的目标， 为患有儿童脑肿瘤的儿童开发有针对性的治疗方法的翻译研究已经成熟。

We and others have recently found that activating mutations in the serine/threonine kinase BRAF may be found in as many as half of all pediatric low grade astrocytomas (LGA). The overarching goals of these studies are to characterize the role of mutant BRAF in these tumors and to identify other mutations that drive the formation of both low- and high-grade pediatric astrocytomas. Specifically, we propose to: Aim One: Use new "paraffin-friendly" genomic technologies to identify oncogenic mutations in pediatric astrocytomas. The ability to interrogate formaldehyde-fixed, paraffin-embedded archival tissues expands the available sample sets of these infrequent pediatric tumors by a factor of ten or more relative to fresh frozen tumor collections. We will use these technologies on a unique set of over 1000 archival tumor samples to address two important unresolved questions in the field. Specifically, (i) what are the recurrent mutations or amplifications in pediatric astrocytomas that lack BRAF mutations? and (ii) What are the mutations that co-occur with BRAF mutations? Aim Two: Use functional approaches to identify mutations that cooperate with activated BRAF in pediatric astrocytomas. Similarto what has been found in BRAF-mutant melanoma, we anticipate that other mutations cooperate with mutated BRAF in pediatric astrocytomas. We will use both candidate and unbiased approaches to identify such mutations through the transformation of neural progenitor cells. Aim Three: identify "druggable" signal generators that function upstream and downstream of BRAF n transformed neural progenitors. In the fullness of time, small molecule inhibitors of BRAF may be used for the treatment of BRAF mutant pediatric LGAs. However, multiple protein kinases have been shown to be co-activated in high-grade adult gliomas, and this is also likely to be the case in mutant BRAF-transformed pediatric astrocytomas. In this Aim, we will conduct kinome-wide genetic screens for kinases that can substitute for activated BRAF to dysregulate the proliferation of normal neural progenitor cells. This information will help define genes that may drive pediatric astrocytomas that lack BRAF mutations as well as defining potential mechanisms of resistance to the inhibition of BRAF. All three specific aims are supported by an Innovative Neuro Pathology Core and by shared technologies and reagents from Projects Two and Three. RELEVANCE (See instructions): Many pediatric brain tumors can be initially treated by surgery, chemotherapy and/or radiotherapy. However, the clinical side-effects ofthese treatments in growing children can be significant. Moreover, these tumors frequently recur and eventually fail to respond to standard treatment protocols. Thus, there is an urgent need for targeted therapeutics for these tumors. This project will identify and characterize promising targets that are ripe for translational studies to develop targeted therapeutics for children with pediatric brain tumors.