Role of Ascl1 in glioma

描述(申请人提供)：原发恶性胶质瘤是一种无法治愈的脑瘤，每年影响数千人。虽然癌基因和抑癌基因的改变已被描述为脑胶质瘤的发病机制，但对脑胶质瘤发生发展的生物学机制或肿瘤形成和发展所必需的遗传机制知之甚少。ASCL1是一种碱性螺旋-环-螺旋转录因子，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，神经前体细胞可能是胶质瘤的起源细胞。由于Ascl1在发育过程中的神经前体细胞和成人脑中都有表达，并且最近被证明直接调节细胞周期调节，因此推测Ascl1在神经胶质瘤的发生中发挥重要作用。该项目的初步证据表明，Ascl1在早期脑瘤的一部分细胞中高度表达，在恶性星形细胞瘤小鼠模型的晚期脑瘤的外围细胞中高度表达。该项目的目标包括采用基因策略诱导和直接可视化小鼠脑内肿瘤的发展，免疫组织化学方法描述Ascl1在肿瘤多个发育阶段的表达，以及使用荧光激活细胞分选(FACS)来分离和表征体外和体内表达Ascl1的肿瘤细胞的致瘤特性。最后，在这个胶质瘤小鼠模型中，Ascl1对肿瘤形成和进展的需求将通过有条件地删除Ascl1来直接测试。这项研究的结果将是 为胶质瘤肿瘤的异质性和分子机制提供新的见解。

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.