Characterizing TP53 and PPM1D mutations as resistance drivers to radiation therapy in Diffuse Intrinsic Pontine Gliomas

摘要 被诊断为弥漫性桥脑胶质瘤(DIPGs)的儿童面临着100%的死亡率。这个 目前的护理标准是放射治疗。尽管取得了初步的反应，但肿瘤很快就表现出来了 抵抗，并开始再次增长。我们在一项全国性的测试中占据了领先地位，DIPG-BATS，这已经 评价儿童DIPGs的常规活检。我们试图利用通过 DIPG-BATS试验以了解DIPG的遗传基础及其对治疗反应的影响。我们 还要设法确定足以防止获得辐射抵抗力的治疗组合。 在目标1中，我们建议分析迄今为止最大的DIPG全基因组集。我们将结合排序 在DIPG-BATS试验中收集的数据来自新诊断的患者，除了之前 已公布的基因组。在目标2中，我们将评估PPM1D突变在产生辐射抗性中的作用 心理治疗。我们对蝙蝠活组织的初步分析显示，超过50%的DIPG基因组包含突变 在PPM1D或TP53中，这些突变是相互排斥的。PPM1D的特征是 TP53的负调节因子，它是辐射敏感性的关键促进剂。在目标3中，我们将使用这两个假设- 基于和不偏不倚的方法，以确定与放射治疗的组合，以提高疗效。我们 将利用遗传和药理学方法结合辐射抑制PPM1D和MDM2 在具有TP53突变的患者来源的DIPG系中。我们还将进行全基因组CRISPR-Cas9筛查 目的：鉴定DIPG相关细胞系中选择性增强辐射反应的抑制基因。这些 实验将解决至少三个关于DIPG对放射治疗的抵抗力的核心问题： 驾驶员基因组改变的特征和对辐射抗性的鉴定 治疗，确定P53信号的改变如何赋予辐射抵抗力，以及评估 PPM1D作为一种新的治疗靶点。

Abstract Children diagnosed with Diffuse Intrinsic Pontine Gliomas (DIPGs) are faced with a mortality rate of 100%. The current standard of care is radiation therapy. Despite achieving initial responses, tumors quickly exhibit resistance and start to grow again. We have taken leading positions in a national trial, DIPG-BATs, that has evaluated routine biopsy of DIPGs in children. We seek to take advantage of the tissue obtained through the DIPG-BATs trial to understand the genetic underpinnings of DIPG and their impact on therapeutic response. We also seek to identify therapeutic combinations that are sufficient to prevent the acquisition of radiation resistance. In Aim 1, we propose to analyze the largest set of DIPG whole genomes to date. We will combine sequencing data collected on the DIPG-BATs trial with those from newly diagnosed patients, in addition to previously published genomes. In Aim 2, we will evaluate the role of PPM1D mutations in generating resistance to radiation therapy. Our initial analysis of BAT biopsies has revealed that over 50% of DIPG genomes contain mutations in either PPM1D or TP53, and that these mutations are mutually exclusive. PPM1D has been characterized as a negative regulator of TP53, a critical facilitator of radiation sensitivity. In Aim 3, we will use both hypothesis- based and unbiased approaches to identify therapeutic combinations with radiation that increase efficacy. We will utilize genetic and pharmacological methods of inhibiting PPM1D and MDM2 in combination with radiation in patient-derived DIPG lines with TP53 mutations. We will also perform a genome-wide CRISPR-cas9 screen to identify genes whose suppression selectively increase radiation response in DIPG-relevant cell lines. These experiments will address at least three central questions regarding resistance to radiation therapy in DIPG: characterization of driver genomic alterations and identification of those that confer resistance to radiation therapy, determination of how alterations in p53 signaling confer resistance to radiation, and evaluation of PPM1D as a novel therapeutic target.