The Roles of MicroRNAs in Glioblastoma

描述（由申请人提供）：胶质母细胞瘤（GBM）是成人中最常见和侵袭性最强的原发性脑肿瘤，目前无法治愈，平均生存期略高于最初诊断的一年。尽管在了解与GBM进展相关的遗传变化方面取得了重大进展，但在基于从病理特征和患者预后后果之间的分子联系分析中收集的信息开发出更好的治疗方法之前，还需要了解更多。在这方面，我们研究了与CD133+胶质瘤干细胞/肿瘤起始细胞（GSCs）对缺氧条件反应相关的microrna表达谱的变化。我们的初步数据表明，CD133+ GSCs在缺氧培养条件下，一组microrna的表达谱发生了显著变化，这表明它们可能在这些细胞对缺氧应激的生物学反应中发挥作用。此外，通过对该组中选定的少数mirna的表达进行操作，可以导致CD133+ GSCs接种到裸鼠颅内环境中的异种移植物生长以及培养中它们的生长和神经球形成发生显著变化，这表明这些mirna调节了这些细胞的特定病理活性。同时，我们获得了缺氧诱导miRNA加工调控的证据，揭示了缺氧引起miRNA表达谱变化的信号通路的分子性质。为了进一步探索这些发现，我们提出了三个具体目标：1。继续确定一些microrna的功能作用和作用机制，这些microrna的表达与GSCs中的缺氧反应相关。2. 利用已建立的转基因小鼠模型探索这些鉴定出的mirna在肿瘤形成/进展中的作用。3. 研究在GSCs缺氧反应中，通过Drosha复合物调节miRNA加工的调节机制。我们将采用细胞培养和小鼠模型来实现这些目标。

DESCRIPTION (provided by applicant): Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults that is currently incurable with an average survival of slightly more than one year past the initial diagnosis. Although significant progress has been made in understanding the genetic changes associated with the progression of GBM, much more needs to be learned before better treatment for this disease can be developed based on information gathered from analysis of molecular links between pathological features and prognostic consequences of patients. In this regard, we have examined changes in the expression profiles of microRNAs associated with responses to hypoxic conditions by CD133+ glioma stem/tumor initiating cells (GSCs). Our preliminary data indicated that a set of microRNAs exhibits significant alterations in their expression profile in response to hypoxic culturing conditions by the CD133+ GSCs, suggesting that they may play roles in the biological responses of these cells to the hypoxic stress. Furthermore, manipulation on the expression of a selected few miRNAs from this group led to significant changes in the xenograft growth of CD133+ GSCs inoculated into the intracranial environment in nude mice, as well as their growth and neurosphere formation in culture, indicating that those miRNAs modulate specific pathological activities of those cells. In the meantime, we have obtained evidence indicative of hypoxia-induced regulation of miRNA processing, uncovering new insights into the molecular nature of the signaling pathway by which hypoxia acts to elicit changes in miRNA expression profile. To further explore these findings, we propose three specific aims: 1. Continue the determination of the functional roles and acting mechanisms of a selected number of microRNAs whose expression is correlated with hypoxic response in GSCs. 2. Explore the roles of those identified miRNAs on tumor formation/progression using an established transgenic mouse model. 3. Examine the regulatory mechanisms that modulate miRNA processing by the Drosha complex in response to hypoxia in GSCs. We will employ both cell culture and mouse models to accomplish these objectives.