SOMATIC CELL TRANSFER TO MODEL MEDULLOBLASTOMA IN MICE

描述（由申请人提供）：本研究的临床重点是髓母细胞瘤（MB），一种发生于儿童小脑的恶性脑肿瘤。目前治疗的主要限制是抗癌药物对发育中的大脑造成附带损害。对MB基本生物学的进一步了解将有助于对干扰肿瘤细胞生长而不阻碍神经发育的新治疗方法的深入了解。本研究的总体目标是使用基因定义的MB小鼠模型，我们使用RCAS/tv-a系统创建，以识别MB形成中的关键信号蛋白。该系统利用来自禽白血病病毒亚群a （ALV-A）的逆转录病毒载体（RCAS）和在巢蛋白基因启动子控制下表达TVA （ALV-A受体）的转基因小鼠系（Ntv-a）。巢蛋白基因编码一种中间丝蛋白，由神经祖细胞在向神经元或胶质细胞分化之前表达。这使得将外源基因特异性地表达到小脑中表达巢蛋白的神经祖细胞（MB的起源细胞）成为可能。具体目的1是通过使用RCAS/tv-a系统，在神经祖细胞中转移刺激增殖、阻断分化和抑制凋亡的基因组合，生成MB的体内小鼠模型。特异性目的2是利用rcas介导的基因转移产生的MBs建立细胞系。利用这些细胞系，我们将在药理学上阻断由逆转录病毒基因转移激活的个体信号通路，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发展。

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.