PRODUCTION OF ALTERNATIVE FGF RECEPTOR FORMS IN TUMORS

描述（由申请人提供）：多形性胶质母细胞瘤（GBM）是迄今为止最常见的中枢神经系统肿瘤，并且预后不佳。尽管近年来我们对神经胶质细胞恶性肿瘤的遗传和生化变化的理解有所提高，但很少有研究检查RNA剪接异常变化的影响和机制。因为先前的研究已经证明了与GBM相关的许多基因的异常RNA剪接，这是一个有希望的治疗发展的新领域。我们之所以关注成纤维细胞生长因子受体1基因（FGFR1），是因为FGFR1的高亲和力形式在GBM中由于表达和RNA剪接的改变而显著升高。我们已经将异常剪接FGFR1 RNA与多功能RNA结合蛋白（称为多嘧啶束结合蛋白（PTB））的表达显著上调联系起来。这一观察结果导致了一种假设，即gbm相关的正常RNA剪接改变，包括但不限于FGFR1，可以促进胶质肿瘤的起始或生长。我们提出以下具体目的：(1)确定FGFR1 d1环（包括正常剪接）在受体信号传导中的作用，(2)确认FGFR1异常剪接在胶质细胞恶性肿瘤中的功能作用，(3)确认PTB在胶质细胞恶性肿瘤中的表达要求，并确定PTB作用的具体靶点，(4)建立PTB介导的肿瘤发生的小鼠模型。目标1 - 3将采用新的实验工具，允许对异常RNA剪接进行特异性纠正，基因产物的靶向消融，以及全基因组外显子表达谱的应用。目的4将采用成熟的转基因方法来建立星形细胞特异性表达PTB。结果数据将显示FGFR1 RNA剪接或PTB反式作用因子表达的改变是否在胶质细胞恶性肿瘤中发挥作用。更好地了解这一过程可能有助于揭示星形胶质细胞的转化，并为抑制其恶性生长提供新的靶点。

DESCRIPTION (provided by applicant): Glioblastoma multiforme (GBM) are by far the most common tumor of the central nervous system and continue to be associated with a dismal prognosis. Although our understanding of genetic and biochemical changes accompanying glial cell malignancy has improved in recent years, few studies have examined the impact and mechanisms responsible for aberrant changes in RNA splicing. Because previous studies have demonstrated the aberrant RNA splicing of numerous genes associated with GBM, this is a promising new area for therapeutic development. We have focused on the fibroblast growth factor receptor 1 gene (FGFR1) because the level of a high-affinity form of FGFR1 is dramatically elevated in GBM as a result of altered expression and RNA splicing. We have linked the aberrant splicing FGFR1 RNA to a dramatic upregulation in the expression of the multifunctional RNA-binding protein, known as polypyrimidine tract binding protein (PTB). This observation led to the hypothesis that GBM-associated alterations in normal RNA splicing, including but not limited to FGFR1, act to facilitate either initiation or growth of glial tumor either initiation or growth. We propose the following Specific Aims: (1) to define the role of the FGFR1 D1-loop (included by normal splicing) in receptor signaling, (2) to confirm a functional role of aberrant FGFR1 splicing in glial cell malignancy, (3) to confirm a requirement for PTB expression in glial cell malignancy and define the specific targets of PTB action, (4) to develop a mouse model for PTB- mediated oncogenesis. Aims 1 - 3 will employ new experimental tools that allow for the specific correction of aberrant RNA splicing, the targeted ablation of gene products, and the application of genome-wide exon expression profiling. Aim 4 will employ proven transgenic approaches to establish astrocyte-specific expression of PTB. The resulting data will show whether alterations in FGFR1 RNA splicing or PTB trans-acting factor expression play a role in glial cell malignancy. A better understanding of this process may shed light on the transformation of astrocytes and provide new targets for suppressing their malignant growth.