Role of SMARCD3/BAF60C in neurodevelopment and medulloblastoma

项目总结/摘要 髓母细胞瘤（MB）是一种发生在小脑的快速生长和异质性脑肿瘤。第三组，一名 MB的四个亚组（WNT，SHH，第3组和第4组），是最具侵略性和恶性的类型在儿童。 第3组占所有MB的25%-30%，其特征在于诊断时频繁转移，并且最严重 预后虽然手术切除、放疗和化疗对消除某些形式有效， 第3组患者不能用常规疗法治愈，也面临着缺乏分子靶向治疗。 治疗本申请的总体目标是确定调节肿瘤的分子机制。 第3组为转移性播散。迫切需要候选途径，以提供合理的线索， 为患有MB的儿童提供新的有效疗法。初步研究表明，SMARD 3/BAF 60 C SWI/SNF染色质重塑复合物的核心组分SMARCD 3在哺乳动物中高度表达。 第3组MB和浦肯野细胞（PC）的发展小脑。此外，SMARD 3 表达与患者预后不良、MB转移表型和Reelin基因的激活相关。 在小脑发育过程中PC迁移和定位所需的信号通路。中央 本申请的假设是SMARCD 3相关的SWI/SNF染色质重塑复合物 在小脑发育过程中，Reelin信号通路调节PC迁移和定位;然而， 神经发育程序被劫持用于MB转移性传播。中心假设将被检验 通过追求两个具体目标：1）调查SMARD 3在PC迁移和定位中的作用， 小脑发育;和2）定义SMARD 3-Reelin信号传导与转移性胶质瘤的机制。 MB中的表型。在第一个目标下，将通过交叉Smarcd 3 flox/flox生成新的小鼠模型 用PC特异性基因启动子（L7/Pcp 2）驱动的Cre小鼠。SMARD 3相关的作用 SWI/SNF染色质重塑复合物在小脑发育中的作用将用这种小鼠进行研究 模型对于第二个目的，在人MB细胞系中的体外和体内获得/丧失功能的方法， 异种移植小鼠模型将用于测试SMARCD 3-Reelin信号传导介导的肿瘤转移 传播。此外，将进行ATAC和ChIP测序，以确定SMARD 3- 相关的SWI/SNF复合物调节Reelin信号通路。本申请中提出的研究 是创新的，因为它专注于理解SMARD 3在神经发育和 髓母细胞瘤，以及肿瘤细胞劫持神经发育信号导致转移的前景。 这项拟议的研究意义重大，因为它有望提供令人信服的功能证据， SMARCD 3和相关的SWI/SNF复合物参与小脑发育、肿瘤转移， 以及早期脑发育和肿瘤发生之间的分子联系。最终，这些知识 有可能为MB患者的创新疗法的开发提供新的理论基础。

Project Summary/Abstract Medulloblastoma (MB) is a fast-growing and heterogeneous brain tumor arising in the cerebellum. Group 3, one of four MB subgroups (WNT, SHH, Group 3, and Group 4), is the most aggressive and malignant type in children. Group 3, accounting for 25%-30% of all MB, is characterized by frequent metastasis at diagnosis and the worst prognosis. Although surgical resection, radiotherapy, and chemotherapy are effective at eliminating some forms, patients with Group 3 cannot be cured with conventional therapies and also face a paucity of molecularly targeted therapies. The overall objective in this application is to define the molecular mechanisms that regulate tumor metastatic dissemination in Group 3. Candidate pathways are critically needed to provide rational leads for enabling new and effective therapies for children with MB. Preliminary studies reveal that SMARCD3/BAF60C (SMARCD3 hereafter), a core component of SWI/SNF chromatin-remodeling complexes, is highly expressed in Group 3 MB and Purkinje cells (PCs) of the developing cerebellum. Furthermore, elevated SMARCD3 expression is associated with patient poor outcomes, MB metastatic phenotype, and activation of the Reelin signaling pathway that is required for PC migration and positioning in cerebellar development. The central hypothesis of this application is that the SMARCD3-associated SWI/SNF chromatin-remodeling complex regulates Reelin signaling pathway in PC migration and positioning during cerebellar development; however, this neurodevelopmental program is hijacked for MB metastatic dissemination. The central hypothesis will be tested by pursuing two specific aims: 1) investigate the role of SMARCD3 in PC migration and positioning during cerebellar development; and 2) define the mechanism linking SMARCD3-Reelin signaling to metastatic phenotype in MB. Under the first aim, a new mouse model will be generated by crossing the Smarcd3 flox/flox mouse with a PC-specific gene promoter (L7/Pcp2)-driven Cre mouse. The role of SMARCD3-associated SWI/SNF chromatin-remodeling complexes in cerebellar development will be investigated using this mouse model. For the second aim, in vitro and in vivo gain/loss-of-function approaches in human MB cell lines and xenograft mouse models will be used to test SMARCD3-Reelin signaling-mediated tumor metastatic dissemination. Additionally, ATAC- and ChIP-sequencing will be performed to determine how SMARCD3- associated SWI/SNF complexes regulate the Reelin signaling pathway. The research proposed in this application is innovative because it focuses on understanding the role of SMARCD3 in both neurodevelopment and medulloblastoma, and the prospect of tumor cells hijacking neurodevelopmental signaling resulting in metastasis. The proposed research is significant because it is expected to provide compelling functional evidence of SMARCD3 and the associated SWI/SNF complexes’ involvement in cerebellar development, tumor metastasis, and the molecular connections between early brain development and tumorigenesis. Ultimately, such knowledge has the potential of offering new rationales for the development of innovative therapies for patients with MB.