CDK9-mediated processive transcription in H3K27M+ diffuse intrinsic pontine glioma

提案摘要 弥漫性桥脑胶质瘤是一种侵袭性脑干肿瘤，目前尚无有效治疗方法 available. DIPG是由组蛋白3基因（H3 K27 M）中的复发性突变驱动的。这种替代 赋予调节募集的组蛋白翻译后修饰（PTM）广泛的失调 和转录机制的启动。进行性转录，或RNA Pol II的机制，因为它积极 跨染色质转录，既依赖于染色质状态，又积极传播染色质状态，如动态 可及性和转录相关的PTM（tPTM）。转录动力学紊乱 在癌症发展中表现出致病作用，抑制转录机制是一种有效的 在这些模型中。我们最近发现H3 K27 M突变激活了 转录延伸，包括CDK 9。我们已经证明，抑制CDK 9依赖性 转录延伸是DIPG的有效治疗方法，但进行性转录对DIPG的贡献是有限的。 致癌转化是未知的。该提议的总体假设是H3 K27 M突变 促进CDK 9依赖的新生转录，这反过来又有助于建立一个 致癌染色质状态以及对标准护理放射疗法的适应性反应。使用 CRISPR编辑的模型系统、患者来源的培养物以及患者来源的异种移植物和异种移植物两者的组合 同基因工程小鼠模型，我们将测试这一假设，1）定义的作用，进行性 2）确定CDK 9抑制对H3 K27 M介导的肿瘤发生的进行性转录的影响， 转录，和3）表征转录诱导在响应电离辐射中的作用。 成功完成该提案将使我们能够全面绘制H3 K27 M突变的影响 新生的转录环境。这些数据将使我们能够定义一个新的转录框架， 了解DIPG的染色质介导的肿瘤发生，它将展示如何利用这一点， 可以利用转录依赖性来改善源自放射治疗的患者益处。 拟议的职业发展计划利用这些研究提供高级培训， 严格的假设驱动的研究，转录调控的分子研究，和代表性的预- 临床癌症建模。导师团队反映了国家认可的资深科学家，他们拥有 在这些研究领域的专业知识，以及对我的职业发展的坚定承诺。培训 计划概述了我将如何通过教学课程工作，重点研讨会， 国家会议和指导。总的来说，这个培训平台将有助于我过渡到 作为一个基本的翻译研究人员的独立性，长期目标是应用新的染色质和 基于转录的策略可改善DIPG中的患者结局。

PROPOSAL SUMMARY Diffuse intrinsic pontine gliomas (DIPGs) are aggressive brainstem tumors in children with no curative therapies available. DIPGs are canonically driven by recurrent mutations in the histone 3 gene (H3K27M). This substitution imparts broad dysregulation of the histone post-translational modifications (PTMs) that regulate the recruitment and initiation of transcriptional machinery. Processive transcription, or the mechanics of RNA Pol II as it actively transcribes across chromatin, is both dependent on and actively propagates chromatin states such as dynamic accessibility and transcription-associated PTMs (tPTMs). Disorders of transcription dynamics have demonstrated pathogenic roles in cancer development, and inhibition of transcription machinery is an effective therapy in these models. We have recently shown that the H3K27M mutation activates regulators of transcriptional elongation, including CDK9. We have demonstrated that inhibition of CDK9-dependent transcriptional elongation is an effective therapy in DIPG, but the contribution of processive transcription to DIPG oncogenic transformation is unknown. The overall hypothesis of this proposal is that the H3K27M mutation promotes CDK9-dependent nascent transcription, which in turn contributes to both the establishment of an oncogenic chromatin state as well as the adaptive response to standard-of-care radiation therapy. Using a combination of CRISPR-edited model systems, patient derived cultures, and both patient-derived xenograft and syngeneic engineered mouse models, we will test this hypothesis by 1) defining the role of processive transcription in H3K27M-mediated oncogenesis, 2) determining the impact of CDK9 inhibition on processive transcription, and 3) characterizing the role of transcriptional induction in response to ionizing radiation. Successful completion of the proposal will allow us to comprehensively map the impact of the H3K27M mutation on the nascent transcriptional landscape. This data will enable us to define a novel transcriptional framework for understanding DIPG’s chromatin-mediated oncogenesis, and it will demonstrate how exploiting this transcriptional dependence may be leveraged to improve the patient benefit derived from radiation therapy. The proposed career development plan leverages these studies to provide advanced training in the conduct of rigorous hypothesis-driven research, the molecular study of transcriptional regulation, and representative pre- clinical cancer modeling. The mentorship team reflects nationally-recognized senior scientists who possess both focused expertise in these areas of study as well as a strong commitment to my career development. The training plan outlines how I will refine my expertise through a combination of didactic course work, focused workshops, national meetings, and mentorship guidance. Collectively, this training platform will facilitate my transition to independence as a basic-translational researcher with a long-term goal of applying novel chromatin- and transcription-based strategies to improve patient outcomes in DIPG.