Developmental studies to inform clinical stratification and targeting of SHH MB

 描述(申请人提供)：最近的全基因组分析已经改变了髓母细胞瘤(MB)的诊断，这是儿童最常见的恶性脑瘤。现在已经清楚的是，MB不是一种单一的小脑疾病，而是包括一系列具有不同临床表现、组织学和途径激活、起源细胞和癌症遗传学的疾病亚组。鉴于甲基溴的复杂性，为每个患者量身定做的针对性治疗的开发将需要更深入地了解导致这种疾病的主要途径，并进一步细分目前的4个患者亚组。Sonic Hedgehog(SHH)亚型约占MBS的30%，预后中等，可由SHH引起的颗粒细胞前体细胞(GCP)增殖而产生。MB的SHH亚型在所有水平上都是不同的，每个因素都可能影响预后，并对治疗至关重要。亏损额 功能突变见于抑制SHH信号的基因(Ptch1)，激活受体SMO的突变(例如SmoM2)，以及与TP53丢失相关的效应基因GLI2及其靶点的扩增。目前的HH抑制剂只对一小部分MBS有效，所有患者都会产生耐药性。我们推测，SHH-MBS中的某些肿瘤间异质性是由于它们来自不同的细胞谱系、不同的时间和CB的不同解剖区域。此外，细胞和转录 从不同来源的细胞继承的状态在成熟的肿瘤中保持不变，可能是治疗的靶点。因此，小鼠模型的基本研究方法是翻译研究的基础。20年来，我们一直在研究哺乳动物发育中的SHH-GLI途径，重点是CB。最近，我们建立了ptch1或Smo突变的散发性MB模型。值得注意的是，在每种模型的肿瘤进展过程中都可以看到可复制但不同的组织结构。此外，大多数早期发现的病变退化，并具有与进展为MB的病变不同的细胞表型。目的：1.对两个发育阶段和谱系的ptch1和SmoM2模型进行标记分析和纵向增强磁共振成像(Turnbull)，找出影响SHH-MBS进展的候选内源基因(RNA-seq图谱)。目的2.定义微环境并检测肿瘤相关的小胶质细胞和巨噬细胞如何影响SHH-MB进展。目的3.确定AIMS 1/2、mTOR信号或NR2F2中确定的候选基因是否会改变SHH-MB进展，并将结果与人类SHH-MB数据集(Taylor)和肿瘤样本进行比较。我们在小鼠模型上进行的MB进展的实验研究将与人类MB研究协同，并应有助于SHH亚组患者的分层，其中可以测试针对推动MB进展的基本途径的新疗法，从而改善幸存者的预后和生活质量。

 DESCRIPTION (provided by applicant): Recent genome-wide analyses have changed the diagnosis of medulloblastoma (MB), the most common malignant brain tumor in children. It is now clear that MB is not a single disease of the cerebellum (CB), but encompasses a range of disease subgroups with diverse clinical presentations, histology, and pathway activation, cells of origin and cancer genetics. Given the complexity of MB, development of targeted therapies tailored to each patient will require deeper insight into the major pathways fueling the disease and further subdivision of the current 4 subgroups of patients. The sonic hedgehog (SHH) subgroup represents ~30% of MBs, has intermediate prognosis, and can arise from granule cell precursors (GCPs) that proliferate in response to SHH. The SHH subgroup of MB is diverse at all levels, and each factor is likely to influence prognosis and be critical for treatment. Loss-of function mutations are seen in genes that inhibit SHH signaling (PTCH1), activating mutations in the receptor SMO (e.g. SmoM2) and amplifications of the effector gene GLI2 and its targets associated with loss of TP53. Current HH inhibitors are only effective in a small percentage of MBs, and all patients develop resistance. We hypothesize that some of the intertumoral heterogeneity within SHH-MBs is due to their arising from different cell lineages, at different times, and in different anatomic regions of the CB. Additionally, that cellular and transcriptional states inherited from distinct cells of origin are maintained in the mature tumor, and could represent targets for therapy. Basic research approaches in mouse models are thus necessary as a foundation for translational studies. We have studied the SHH-GLI pathway in mammalian development for 20 years, with a focus on the CB. Recently we developed sporadic MB models with mutations in Ptch1 or Smo. Significantly, reproducible yet distinct histologies are seen during tumor progression in each model. Moreover, the majorities of lesions seen at early stages regresses and have different cellular phenotypes to lesions that progress to MB. We propose to: Aim 1. Marker analysis and longitudinal Mn-Enhanced MRI (Turnbull) of Ptch1 and SmoM2 models initiated at 2 developmental stages and lineages, and identify candidate intrinsic genes that influence progression of SHH-MBs (RNA-seq profiling). Aim 2. Define the microenvironment and test how tumor associated microglia and macrophages influence SHH-MB progression. Aim 3. Determine whether select candidate genes identified in Aims 1/2, mTOR signaling or NR2F2 alter SHH- MB progression and compare the results to human SHH-MB data sets (Taylor) and tumor samples. Our experimental studies of MB progression in mouse models will synergize with human MB studies and should aid in stratification of SHH subgroup patients, wherein new therapies targeted to essential pathways driving MB progression can be tested, improving both prognosis and quality of life for survivors.