glioma Through Genomics and Transgenic Mouse Model

描述（由申请方提供）：胶质瘤是最常见的原发性脑恶性肿瘤。胶质瘤的最高级形式，也是最具侵袭性的，是胶质母细胞瘤或GBM，其占所有胶质瘤的50-60%。GBM患者的中位生存期不到一年。只有大约20%的患者对治疗有反应，并且在初步诊断后存活超过1.5年。在过去二十年中的深入研究已经证明，癌症随着遗传和分子改变的积累而进展，所述遗传和分子改变使得细胞能够获得至少六种能力（Hanahan和温伯格，细胞100：57-70，2000）。已经积累了来自体外和体内模型系统的证据，在基因表达水平上鉴定了其中的一些事件。包括转基因和敲除模型在内的动物模型已被用于测试体内环境中一些鉴定的分子事件的重要性（货车Dyke和Jacks，2002）。例如，EGFR的表达（Holland等人，1998）、PDGF（Dai等人，2002）、K-ras与akt的组合（Holland等人，2000），已经显示在转基因模型中诱导神经胶质瘤，这对于整理肿瘤形成和肿瘤表型中的关键事件是什么是非常有价值的。一些模型，例如由Holland和Varmus开发的神经胶质特异性小鼠模型（RCAS/tv-a系统）（Holland等人，1998）允许在一个实验环境中转基因表达多个基因，因此可以评估基因组合的效果。使用基因组学和信息学方法，我们已经分析了不同级别的神经胶质瘤中的基因表达，并鉴定了在GBM中独特过表达的基因，例如胰岛素样生长因子结合蛋白2（IGFBP 2）（Fuller et al.，1999年）。我们的导入实验表明IGFBP 2过表达的细胞更具侵袭性。IGFBP 2还与GBM中缩短的存活相关（Sallinen等人，2000年，以及我们未公布的数据）。这些研究使我们假设IGFBP 2是导致GBM细胞侵袭和GMB患者生存期短的关键分子。我们还假设IGFBP 2过表达在胶质瘤进展为GBM中起积极作用。在这个项目中，我们建议使用RCAS/tv-a小鼠模型来检验假设。 我们进一步假设，在小鼠中开发的GBM与人GBM同源，这可以通过比较基因表达谱以及集中的基因集来评估。这三个具体目标是：（1）测试IGFBP 2是否增强GBM发育，缩短GBM小鼠的存活，并增加体内GBM细胞侵袭。(2)研究IGFBP 2是否在低级别胶质瘤向GBM的进展中起重要作用。(3)利用基因表达谱对小鼠胶质瘤进行表征。通过这个项目，我们希望丰富我们对IGFBP 2通路的知识，这些通路可能对胶质瘤的发展和进展很重要;我们还希望使用基因组学方法来评估小鼠胶质瘤是否在基因表达水平上忠实地代表人类胶质瘤。

DESCRIPTION (provided by applicant): Glioma represents the single most frequent primary brain malignancy. The most advanced form of glioma, also the most invasive, is glioblastoma or GBM that comprises 50-60% of all gliomas. The median survival for GBM patients is less than a year. Only about 20% of patients respond to therapy and live for more than 1.5 years following initial diagnosis. Intensive research during the last two decades has demonstrated that cancer progresses with an accumulation of genetic and molecular alterations that enables cells to acquire at least six capabilities (Hanahan and Weinberg, Cell 100:57-70, 2000). Evidence from in vitro and in vivo model systems has been accumulated that identifies some of those events at gene expression level. Animal models including transgenic and knockout models have been used to test the importance of some of the identified molecular events in in vivo setting (van Dyke and Jacks, 2002). For example, expression of EGFR (Holland et al., 1998), PDGF (Dai et al., 2002), K-ras in combination with akt (Holland et al., 2000), have been shown to induce gliomas in transgenic models, which has been highly valuable to sort out what the key events are in tumor formation and tumor phenotypes. Some models, such as the glial-specific mouse model (the RCAS/tv-a system) developed by Holland and Varmus (Holland et al., 1998) permit transgenic expression of multiple genes in one experimental setting thus the effect of gene combination can be evaluated. Using genomics and informatics approaches, we have profiled gene expression in different grades of gliomas and identified genes, such as insulin-like growth factor binding protein 2 (IGFBP2), that are uniquely overexpressed in GBM (Fuller et al., 1999). Our in intro experiments showed that IGFBP2 overexpressing cells was more invasive. IGFBP2 was also associated with shortened survival in GBMs (Sallinen et al., 2000, and our unpublished data). These studies led us to hypothesize that IGFBP2 is a key molecule that contributes to invasion of GBM cells and short survival of GMB patients. We also hypothesize that IGFBP2 overexpression plays a positive role in glioma progression to GBMs. In this project, we propose to test the hypotheses using the RCAS/tv-a mouse model. We further hypothesize that GBMs developed in mice are homologous to human GBMs and this can be evaluated by comparative gene expression profiling as well as focused set of genes. The three specific aims are: (1) To test whether IGFBP2 enhances GBM development shortens survival of GBM mice, and increases GBM cell invasion in vivo. (2) To examine whether IGFBP2 plays an important role in progression from low-grade glioma to GBM. (3) To characterize mouse gliomas using gene expression profiling. Through this program, we want to enrich our knowledge of IGFBP2 pathways that are likely important for glioma development and progression; we also want to use genomics approach to evaluate whether mouse gliomas faithfully represent human gliomas at gene expression levels.