Role of Ascl1 in glioma

描述（申请人提供）：原发性恶性胶质瘤是一种无法治愈的脑肿瘤，每年影响成千上万的人。虽然癌基因和肿瘤抑制基因的改变已被描述为胶质瘤的发病机制，但对胶质瘤发展的生物学或肿瘤形成和进展所必需的遗传机制知之甚少。Ascl1是一种碱性螺旋-环-螺旋（bHLH）转录因子，在许多癌症中异常上调，包括具有神经内分泌特征的肺癌和恶性星形细胞瘤。恶性星形细胞瘤的小鼠模型最近表明神经祖细胞可能是胶质瘤的起源细胞。鉴于Ascl1在发育过程中的神经祖细胞和成人大脑中表达，并且最近被证明直接调节细胞周期调节因子，假设Ascl1在胶质瘤形成中起重要作用。该项目的初步证据表明，Ascl1在恶性星形细胞瘤小鼠模型的早期脑肿瘤细胞亚群和终末期脑肿瘤周围细胞中高度表达。该计划的目标包括在小鼠大脑中诱导和直接可视化肿瘤发展的遗传策略，描述肿瘤多个发展阶段Ascl1表达的免疫组织化学，以及使用荧光激活细胞分选（FACS）在体外和体内分离和表征表达Ascl1的肿瘤细胞的致瘤特性。最后，我们将通过条件删除Ascl1直接检测该小鼠胶质瘤模型中肿瘤形成和进展对Ascl1的需求。这项研究的高潮将

DESCRIPTION (provided by applicant): Primary malignant gliomas are incurable brain tumors that affect thousands of people every year. Although alteration of oncogenes and tumor suppressors genes have been described to contribute to the pathogenesis of gliomas, very little is known about the biology of glioma development or the genetic mechanisms that are essential for tumor formation and progression. Ascl1, a basic-helix-loop-helix (bHLH) transcription factor, is aberrantly upregulated in a number of cancers, including lung cancers with neuroendocrine features and malignant astrocytoma. Mouse models of malignant astrocytoma recently indicated that neural progenitors may be the cells of origin for glioma. Given that Ascl1 is expressed in neural progenitors during development as well as in the adult brain, and was recently shown to directly regulate cell cycle regulators, it is hypothesized that Ascl1 plays an important role in gliomagenesis. Preliminary evidence for the proposed project demonstrates that Ascl1 is highly expressed in a subset of cells of an early stage brain tumor and in cells at the periphery of a terminal stage brain tumor of a mouse model of malignant astrocytoma. The aims of the proposed project include genetic strategies to induce and directly visualize tumor development in the brains of mice, immunohistochemistry to describe the expression of Ascl1 in tumors at multiple stages of development, and use of fluorescence activated cell sorting (FACS) to isolate and characterize the tumorigenic properties of Ascl1-expressing tumor cells in vitro and in vivo. Finally, the requirement for Ascl1 for tumor formation and progression in this mouse model of glioma will be directly tested by conditional deletion of Ascl1. The culmination of this study will provide new insights into the heterogeneity and molecular mechanisms of glioma tumors.