Role of Ascl1 in glioma

描述（由申请人提供）：原发性恶性神经胶质瘤是一种无法治愈的脑肿瘤，每年影响数千人。虽然癌基因和肿瘤抑制基因的改变已被描述为有助于神经胶质瘤的发病机制，但对神经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。Ascl 1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。最近的恶性星形细胞瘤小鼠模型表明，神经祖细胞可能是胶质瘤的起源细胞。考虑到Ascl1在发育过程中以及在成人脑中在神经祖细胞中表达，并且最近显示直接调节细胞周期调节剂，假设Ascl1在胶质瘤发生中起重要作用。该项目的初步证据表明，Ascl1在早期脑肿瘤的细胞亚群和恶性星形细胞瘤小鼠模型的终末期脑肿瘤的外周细胞中高度表达。该项目的目的包括遗传策略，以诱导和直接可视化肿瘤在小鼠脑中的发展，免疫组化描述Ascl1在肿瘤中的表达在多个发展阶段，并使用荧光激活细胞分选（FACS）分离和表征Ascl1表达肿瘤细胞在体外和体内的致瘤特性。最后，在该胶质瘤小鼠模型中肿瘤形成和进展对Ascl 1的需求将通过Ascl 1的条件性缺失直接测试。这项研究的结果将 为神经胶质瘤的异质性和分子机制提供了新的见解。

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.