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，并继续与预后不良相关。虽然近年来我们对伴随胶质细胞恶性肿瘤的遗传和生化变化的理解有所提高，但很少有研究探讨RNA剪接异常变化的影响和机制。由于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，因此这是一个有希望的治疗开发新领域。我们关注成纤维细胞生长因子受体1基因（FGFR 1），因为由于表达和RNA剪接的改变，GBM中FGFR 1的高亲和力形式的水平显著升高。我们已经将异常剪接的FGFR 1 RNA与多功能RNA结合蛋白（称为聚嘧啶束结合蛋白（PTB））表达的显著上调联系起来。这一观察结果导致了这样的假设，即正常RNA剪接中的GBM相关改变，包括但不限于FGFR 1，起到促进神经胶质肿瘤起始或生长的作用。我们提出以下具体目标：（1）定义FGFR 1 D1环的作用（包括通过正常剪接）在受体信号传导中的作用，（2）证实异常FGFR 1剪接在胶质细胞恶性肿瘤中的功能作用，（3）证实胶质细胞恶性肿瘤中PTB表达的需要并定义PTB作用的特异性靶标，（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，允许特异性纠正异常RNA剪接，靶向消融基因产物，并应用全基因组外显子表达谱。目的4将采用已证实的转基因方法来建立PTB的星形胶质细胞特异性表达。所得数据将显示FGFR 1 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起作用。更好地了解这一过程可能有助于了解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.