Project 4: The BRCA Network in Medulloblastoma Responses to Replication Stress

项目 4：髓母细胞瘤中 BRCA 网络对复制压力的反应

• 批准号: 10396611
• 负责人: Zhiyuan Shen
• 金额: $ 42.25万
• 依托单位: RBHS -CANCER INSTITUTE OF NEW JERSEY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-01 至 2023-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10396611
• 关键词: Aftercare; BRCA mutations; BRCA1 gene; BRCA2 gene; Binding; Brain Neoplasms; C-terminal; CDKN1A gene; Cells; Cessation of life; Characteristics; Chromosomal Breaks; Chromosomes; Code; Complex; DNA Binding Domain; DNA Damage; DNA Repair; DNA Repair Gene; DNA biosynthesis; DNA replication fork; DNA strand break; Data; Defect; Development; Down-Regulation; Embryo; Epigenetic Process; Exhibits; Functional disorder; Genes; Genome; Genomics; Germ-Line Mutation; Glial Fibrillary Acidic Protein; Goals; Health; Human; Hypersensitivity; In Vitro; Individual; Malignant Childhood Neoplasm; Malignant Neoplasms; Mammary gland; Mediating; Modeling; Molecular; Mus; Mutation; Organ; Ovary; PALB2 gene; Pancreas; Patients; Pediatric Neoplasm; Penetration; Pharmaceutical Preparations; Play; Progression-Free Survivals; Prostate; Proteins; Radiation; Recurrence; Risk; Role; Signal Transduction; Site; Structure; Testing; Time; Topoisomerase; Treatment Protocols; Ursidae Family; Ustilago; base; brca gene; cancer predisposition; chemotherapy; conditional knockout; efficacy validation; gene network; genome-wide; genomic biomarker; genomic signature; high risk; homologous recombination; inhibitor; irinotecan; knock-down; medulloblastoma; medulloblastoma cell line; neoplastic cell; novel therapeutic intervention; novel therapeutics; preclinical study; promoter; recruit; replication stress; response; stem cells; success; targeted treatment; therapeutic development; treatment response; tumor; tumorigenesis

The BRCA Network in Medulloblastoma Responses to Replication Stress (Project-4) Abstract: BRCA1 and BRCA2 are critical genes for the repair of DNA strand breaks (DSB) via homologous recombination (HR). PALB2 functions to bridge BRCA1 with BRCA2. Due to the intimate relationship between BRCA1, PALB2, and BRCA2, these genes and their coded proteins are considered the core of a “BRCA network.” Cancers with BRCA mutations display unique molecular features of “BRCAness,” including hypersensitivity to replication stress drugs. In addition to the core BRCA proteins, defects of other BRCA1/2- associated genes often share the “BRCAness” characteristics. Brain tumors are the leading cause of childhood cancer-related deaths, and medulloblastomas (MBs) account for more than 60% of pediatric tumors. Current treatments of MBs mainly rely on local control by radiation in combination with generic chemotherapy. Targeted therapy has not been vigorously considered for MBs. Recently, it has been recognized that germline mutations in BRCA2 and PALB2, two of the core genes in the “BRCA Network,” are among the top causes of MBs. Furthermore, widespread basal activation of DNA damage signaling and excessive replication stress were common among different groups of MBs. Based on genomic signatures, 20-30% of sporadic MBs, including those from MB groups 2, 3, and 4, likely bear HR defects (HRD). These recent developments raise an important question of whether DNA damage repair defects and replication stress represent common vulnerabilities of MBs to new therapeutic developments targeting HRD. If so, how to efficiently identify the individual cases with HRD remains an issue. In the preliminary studies, we established conditional knockouts of Brca1, Palb2, and Brca2 in embryonic multi-potential stem and progenitor cells using the glial fibrillary acidic protein (GFAP) promoter-driven Cre expression. For the first time, we demonstrated that conditional loss of Palb2 and Brca1 are effective inducers of MBs, with a similar potency as that of Brca2 loss. An initial genomic characterization of these MBs exhibiting “BRCAness” had identified several unique structural features that can be used to define the HRD status. By treating the de novo MBs with a developing topoisomerase 1 inhibitor, we found it to be very effective to extend the survival of mice with MBs. Thus, we hypothesize that MBs originated from BRCA defects have unique genomic signatures to define the MBs with HRD, and targeted therapy of MBs with HRD will be more effective than the current treatment regimens. In Project-4, we take advantage of our recent success in establishing BRCA-related mouse MB models and strive to identify the genomic signatures associated with HRD and to validate the MB “BRCAness” response to replication stress drugs. Aim 1 will identify the structural and chromosome-context signatures that accurately reflect the HDR status in MBs exhibiting “BRCAness”. Aim 2 will experimentally target the vulnerability of HRD in MBs and investigate the potential mechanism of tumor recurrence after the treatment. The success of this study would effectively establish a new remedy for MB treatment.

BRCA网络在髓母细胞瘤复制应激反应中的作用（项目-4） 摘要： BRCA 1和BRCA 2是通过同源性DNA修复DNA链断裂（DSB）的关键基因。 重组（HR）。PALB 2用于桥接BRCA 1和BRCA 2。由于他们之间的亲密关系， BRCA 1、PALB 2和BRCA 2基因及其编码蛋白被认为是“BRCA”的核心 网络”。具有BRCA突变的癌症显示出独特的“BRCA阴性”分子特征，包括 对复制应激药物过敏。除了核心BRCA蛋白，其他BRCA 1/2- 相关基因通常具有“BRCAness”特征。 脑肿瘤是儿童癌症相关死亡的主要原因，髓母细胞瘤（MB）占 超过60%的儿科肿瘤。目前MB的治疗主要依赖于局部控制， 与一般化疗联合。尚未积极考虑MB的靶向治疗。 最近，人们已经认识到，BRCA 2和PALB 2的生殖系突变，这两个核心基因在肿瘤的发生和发展中起着重要作用。 “BRCA网络”是MB的主要原因之一。此外，DNA的广泛基础激活 损伤信号和过度复制应激在不同MB组中很常见。基于 基因组特征，20-30%的散发性MB，包括来自MB组2、3和4的MB，可能携带HR 缺陷（HRD）。这些最新的进展提出了一个重要的问题，即DNA损伤修复是否 缺陷和复制压力代表了MB对新治疗发展的共同脆弱性 目标是人权捍卫者如果是这样，如何有效地查明与人力资源开发有关的个案仍然是一个问题。 在前期研究中，我们建立了Brca 1、Palb 2和Brca 2的条件性敲除， 使用胶质细胞酸性蛋白（GFAP）启动子驱动的Cre的多潜能干细胞和祖细胞 表情我们首次证明了Palb 2和Brca 1的条件性缺失是有效的诱导剂， MBs，具有与Brca 2缺失相似的效力。这些MB的初始基因组表征表现出 “BRCAness”确定了可用于界定人力资源开发状况的若干独特结构特征。通过 用一种正在发展的拓扑异构酶1抑制剂治疗新生MB，我们发现， 延长了患有心肌梗塞的小鼠的存活时间。因此，我们假设起源于BRCA缺陷的MB 独特的基因组特征来定义HRD MB，HRD MB的靶向治疗将更加重要。 比目前的治疗方法更有效。在项目-4中，我们利用我们最近的成功， 建立BRCA相关的小鼠MB模型，并努力识别与BRCA相关的基因组特征， HRD和验证MB“BRCAness”对复制应激药物的反应。目标1将确定结构 以及准确反映表现出“BRCAness”的MB中的HDR状态的染色体背景特征。 目标2将实验性地针对MBs中HRD的脆弱性，并研究其潜在机制。 治疗后肿瘤复发。这项研究的成功将有效地建立一种新的补救办法， MB处理。