Truncated GLI1 In Glioblastoma

胶质母细胞瘤中 GLI1 截短

• 批准号: 9244862
• 负责人: HUI-WEN LO
• 金额: $ 42.34万
• 依托单位: WAKE FOREST UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-15 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9244862
• 关键词: Address; Adult; Affect; Alternative Splicing; Binding; Biology; Blood Vessels; Brain; Codon Nucleotides; DNA; Elements; Engineering; Exons; Family; GLI gene; Gene Expression; Gene Targeting; Genes; Genetic Transcription; Glioblastoma; Goals; Growth; Health; Heterogeneous-Nuclear Ribonucleoproteins; Human; Infiltration; Investigation; KDR gene; Knock-in; Knowledge; Laboratories; Ligands; Light; Malignant - descriptor; Malignant Neoplasms; Malignant neoplasm of brain; Mediating; Mediator of activation protein; Messenger RNA; Molecular; Monitor; Mus; Normal tissue morphology; Nuclear; Pathway interactions; Patients; Pattern; Phenotype; Process; RNA Binding; RNA Splicing; Ribonucleoproteins; Role; SHH gene; Signal Transduction; Specimen; Survival Rate; Testing; Tumor Tissue; Vascular Endothelial Growth Factors; Xenograft procedure; Zinc Fingers; angiogenesis; cis acting element; clinically relevant; gain of function; insight; knock-down; mRNA Precursor; malignant phenotype; mouse model; novel; nucleocytoplasmic transport; overexpression; promoter; public health relevance; transcription factor; tumor; tumor growth; vector control

DESCRIPTION (provided by applicant): Alternative splicing is observed in ~40-60% of human genes; however, its full impact on human cancers is still not well understood. In this proposal, we will functionally characterize a novel, alternatively spliced transcription factor discovered in the PI's laboratory, namely, tGLI1 (truncated glioma-associated oncogene homolog 1). Belonging to the GLI1 family of zinc finger transcription factors, tGLI1 has an in-frame deletion of entire exon 3 and part of exon 4 of the GLI1 gene. Like GLI1, tGLI1 responds to sonic hedgehog ligand, undergoes nuclear transport, and regulates known GLI1 target genes. However, our preliminary results showed that tGLI1 may differ from GLI1 in regulating tumor phenotypes, transcriptional targets and expression pattern. Glioblastoma multiforme (GBM) xenografts engineered to express tGLI1 appeared to be more aggressive in growth, invasiveness, and angiogenesis than those with GLI1. tGLI1 has gained the ability to enhance expression of several invasion- and angiogenesis-promoting genes. tGLI1 was highly expressed in nearly 50% of GBM specimens we had examined, but undetectable in normal brain or other normal tissues. These observations have led us to hypothesize that the novel tGLI1 transcription factor behaves as a gain-of-function GLI1 that regulates expression of a unique set of genes not targeted by GLI1, and that because of its overexpression in GBM and its ability to enhance genes important for tumor growth, invasion and angiogenesis, tGLI1 supports some of the predominant features of GBM, i.e. high degrees of proliferation, infiltration and vascularity. Three Specific Aims are proposed to test this hypothesis. (1) Determine whether tGLI1 mediates malignant phenotypes of GBM. There has been no systematic study that investigated the role of tGLI1 in distinctive GBM malignant phenotypes. Here, we will create intracranial GBM xenografts with differential levels of tGLI1 via knock-in and knock-down approaches, examine the xenografts for growth, invasiveness and angiogenesis, and monitor the xenograft-carrying mice for survival. (2) Elucidate the mechanisms by which tGLI1 regulates gene expression in GBM. tGLI1 has gained the ability to enhance expression of several genes; however, the underlying mechanisms for this unique ability is currently unknown. Here, we will investigate two potential mechanisms: a) tGLI1 binds to unique DNA elements, not recognized by GLI1, within its target gene promoters and thereby regulates genes not targeted by GLI1; and b) tGLI1 has gained the ability to interact with transcription regulators that do not interact with GLI1, thereb regulating genes not targeted by GLI1. (3) Investigate alternative splicing process that leads to tGLI1 mRNA synthesis in GBM. Alternative splicing process for tGLI1 mRNA synthesis is presently unknown. We will identify the cis-acting elements within the pre-mRNA and the RNA-binding splicing factors that together mediate alternative splicing for tGLI1 mRNA synthesis. Our study will be the first step towards defining tGLI1 as a novel mediator of GBM malignancy, and understanding the full spectrum of tGLI1 functionality and the molecular basis for tGLI1 mRNA synthesis.

描述（由申请人提供）：在约 40-60% 的人类基因中观察到选择性剪接；然而，它对人类癌症的全面影响仍不清楚。在本提案中，我们将从功能上表征一种新的、选择性剪接的转录因子 PI 的实验室，即 tGLI1（截短的神经胶质瘤相关癌基因同源物 1）。 tGLI1属于锌指转录因子GLI1家族，其GLI1基因的整个外显子3和部分外显子4的框内缺失。与 GLI1 一样，tGLI1 响应音刺猬配体，进行核转运，并调节已知的 GLI1 靶基因。然而，我们的初步结果表明，tGLI1 在调节肿瘤表型、转录靶点和表达模式方面可能与 GLI1 不同。表达 tGLI1 的多形性胶质母细胞瘤 (GBM) 异种移植物似乎比含有 GLI1 的异种移植物在生长、侵袭性和血管生成方面更具侵袭性。 tGLI1 具有增强多种侵袭和血管生成促进基因表达的能力。 tGLI1 在我们检查的近 50% GBM 标本中高度表达，但在正常大脑或其他正常组织中检测不到。这些观察结果使我们推测，新型 tGLI1 转录因子充当功能获得性 GLI1，调节 GLI1 未靶向的一组独特基因的表达，并且由于其在 GBM 中的过度表达及其增强对肿瘤生长、侵袭和血管生成重要的基因的能力，tGLI1 支持 GBM 的一些主要特征，即高度的 增殖、浸润和血管分布。提出了三个具体目标来检验这一假设。 (1)确定tGLI1是否介导GBM的恶性表型。目前还没有系统的研究调查 tGLI1 在独特的 GBM 恶性表型中的作用。在这里，我们将通过敲入和敲低方法创建具有不同水平 tGLI1 的颅内 GBM 异种移植物，检查异种移植物的生长、侵袭性和血管生成，并监测携带异种移植物的小鼠的存活情况。 (2)阐明tGLI1调节GBM基因表达的机制。 tGLI1 已获得增强多个基因表达的能力；然而，这种独特能力的潜在机制目前尚不清楚。在这里，我们将研究两种潜在的机制：a) tGLI1 在其靶基因启动子内结合到 GLI1 不识别的独特 DNA 元件上，从而调节 GLI1 不靶向的基因； b) tGLI1 已获得与不与 GLI1 相互作用的转录调节因子相互作用的能力，从而调节 GLI1 不靶向的基因。 (3) 研究导致 GBM 中 tGLI1 mRNA 合成的选择性剪接过程。 tGLI1 mRNA 合成的替代剪接过程目前尚不清楚。我们将鉴定前 mRNA 内的顺式作用元件和 RNA 结合剪接因子，它们共同介导 tGLI1 mRNA 合成的选择性剪接。我们的研究将是第一步，将 tGLI1 定义为 GBM 恶性肿瘤的新型介质，并了解 tGLI1 的全部功能和 tGLI1 mRNA 合成的分子基础。