PRODUCTION OF ALTERNATIVE FGF RECEPTOR FORMS IN TUMORS

描述(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，预后仍然很差。尽管近年来我们对伴随胶质细胞恶性病变的遗传和生化变化的了解有所提高，但很少有研究探讨RNA剪接异常变化的影响和机制。由于以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开发的新领域。我们关注成纤维细胞生长因子受体1基因(FGFR1)，因为在GBM中，由于表达改变和RNA剪接，FGFR1的高亲和力形式的水平显著升高。我们已经将FGFR1RNA的异常剪接与多功能RNA结合蛋白，即多嘧啶结合蛋白(PTB)的表达上调联系在一起。这一观察结果导致了一种假设，即正常RNA剪接中与GBM相关的变化，包括但不限于FGFR1，有助于胶质瘤的启动或生长。我们提出了以下具体目标：(1)明确FGFR1D1环(包括在正常剪接中)在受体信号转导中的作用；(2)确认异常的FGFR1剪接在胶质细胞恶性肿瘤中的功能作用；(3)确定PTB在胶质细胞恶性肿瘤中的表达需求并确定PTB作用的特异性靶点；(4)建立PTB介导的肿瘤发生的小鼠模型。AIMS 1-3将使用新的实验工具，允许特定纠正异常的RNA剪接，有针对性地去除基因产物，并应用全基因组范围的外显子表达谱。AIM 4将使用经过验证的转基因方法来建立PTB的星形胶质细胞特异性表达。由此产生的数据将显示FGFR1RNA剪接或PTB反式作用因子表达的变化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过程，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.