SOMATIC CELL TRANSFER TO MODEL MEDULLOBLASTOMA IN MICE

描述(申请人提供)：这项研究的临床重点是髓母细胞瘤(MB)，一种发生在儿童小脑的恶性脑瘤。目前治疗的主要局限是抗癌药物对发育中的大脑造成的附带损害。对在不阻碍神经发育的情况下干扰肿瘤细胞生长的新治疗方法的洞察将来自对MB基本生物学的更多了解。这项研究的总体目标是使用我们使用RCAS/TV-a系统创建的MB的遗传定义的小鼠模型，以确定MB形成中的关键信号蛋白。该系统利用来源于A亚群禽白血病病毒(ALV-A)的逆转录病毒载体(RCAS)和在Nestin基因启动子控制下表达TVA(ALV-A受体)的转基因小鼠系(NTV-a)。Nestin基因编码一种中间丝蛋白，由神经前体细胞在承诺向神经元或神经胶质分化之前表达。这使得有可能将外源基因的表达靶向于小脑中表达巢蛋白的神经前体细胞--MB的起源细胞。具体目标1是通过使用RCAS/TV-a系统来转移刺激神经前体细胞增殖、阻止分化和抑制凋亡的基因组合，从而建立MB的体内小鼠模型。具体目的2是从RCAS介导的基因转移产生的MBS建立细胞系。利用这些细胞系，我们将从药理学上阻断逆转录病毒基因转移激活的单个信号通路，以评估增殖、分化和凋亡对肿瘤生长的相对贡献。这项研究的结果将为促进MB生长的信号转导途径提供见解。这些信息可用于确定分子治疗靶点，并促进化疗药物临床前测试模型的开发。

DESCRIPTION (provided by applicant): The clinical focus of this research is medulloblastoma (MB), a malignant brain tumor that arises in the cerebellum in children. The main limitation to current therapy is collateral damage to the developing brain by anti-cancer agents. Insights into new treatments that interfere with tumor cell growth without impeding neural development will come from an increased understanding of the basic biology of MB. The overall objective of this research is to use a genetically defined, mouse model of MB, which we created using the RCAS/tv-a system, to identify key signaling proteins in MB formation. This system utilizes a retroviral vector (RCAS), derived from avian leukosis virus, subgroup A (ALV-A), and a transgenic mouse line (Ntv-a) that expresses TVA (the receptor for ALV-A) under control of the nestin gene promoter. The nestin gene encodes an intermediate filament protein expressed by neural progenitor cells prior to their commitment to neuronal or glial differentiation. This makes it possible to target expression of exogenous genes specifically to nestin-expressing neural progenitors in the cerebellum - the cells-of-origin for MB. Specific aim 1 is to generate in vivo mouse models of MB by using the RCAS/tv-a system to transfer combinations of genes that stimulate proliferation, block differentiation, and inhibit apoptosis in neural progenitor cells. Specific aim 2 is to establish cell lines from MBs generated by RCAS-mediated gene transfer. Using these cell lines, we will pharmacologically block the individual signaling pathways activated by retroviral gene transfer in order to assess the relative contribution of proliferation, differentiation, and apoptosis to tumor growth. The results of this study will provide insights into signal transduction pathways that promote MB growth. This information can be used to identify molecular therapeutic targets and facilitate development of preclinical testing models for chemotherapeutic agents.