Mechanisms of tumorigenesis in Brg1 mutant lung cancer

Brg1突变型肺癌的肿瘤发生机制

• 批准号: 10225305
• 负责人: Carla F. Kim
• 金额: $ 65.01万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-20 至 2023-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10225305
• 关键词: ATP phosphohydrolase; Affect; Aftercare; Bioavailable; Cancer Etiology; Cancer Patient; Cancer cell line; Cell Line; Cessation of life; Clinic; Complex; DNA; DNA Double Strand Break; DNA Repair; Data; Defect; Disease; Double Strand Break Repair; EZH2 gene; Epigenetic Process; Etoposide; Genes; Genetic; Genetically Engineered Mouse; Human; Human Engineering; Immune system; Individual; KRAS oncogenesis; KRAS2 gene; Laboratories; Lung Adenocarcinoma; Lung Neoplasms; Malignant Neoplasms; Malignant neoplasm of lung; Maps; Modality; Modeling; Mus; Mutate; Mutation; Non-Small-Cell Lung Carcinoma; Nonhomologous DNA End Joining; Oral; Patients; Pharmaceutical Preparations; Pharmacology; Polycomb; Role; SMARCA4 gene; STK11 gene; SWI/SNF Family Complex; Squamous Cell Lung Carcinoma; Topoisomerase II; Topoisomerase II inhibition; Topoisomerase-II Inhibitor; Tumor-infiltrating immune cells; United States; VP 16; Work; cohort; helicase; homologous recombination; in vivo; inhibitor/antagonist; insight; loss of function; lung cancer cell; lung tumorigenesis; mouse model; mutant; neoplastic cell; patient derived xenograft model; phase I trial; pre-clinical; precision medicine; preclinical study; preclinical trial; standard of care; targeted treatment; transcriptional reprogramming; tumor; tumor-immune system interactions; tumorigenesis

Summary/Abstract Lung cancer is the leading cause of cancer-related deaths both worldwide and in the United States. It is also one of the most genetically complex diseases – the two major subtypes of non-small cell lung cancer (NSCLC), which are lung squamous cell carcinoma and lung adenocarcinoma rank 2nd and 3rd for the most mutations per megabase of DNA in a study of 21 different tumor types. Efforts to map these mutations to genetic regions have demonstrated that mutations in the BRG1-Associated Factor (BAF) complex, also known as the mammalian SWI/SNF complex, are common. Inactivating mutations in BRG1, which encodes the ATPase and helicase of the BAF complex, are present in 8-20% of NSCLCs. BRG1 (also known as SMARCA4) is often co- mutated with KRAS, and there are no targeted therapies for this genetic subtype of lung cancer. The BAF complex has long been known to be the epigenetic antagonist of the EZH2-containing Polycomb Repressive Complex 2 (PRC2), but exactly how these complexes interact in the cancer setting is not well understood. Recently, we demonstrated that EZH2 inhibitors synergize well with Topoisomerase II (TopoII) inhibitors such as etoposide in BRG1 mutant NSCLCs. Our data suggest that a key role for BRG1 in lung cancer cells involves facilitating TopoII complex function. Furthermore, our data suggest that combination of EZH2 inhibition and TopoII inhibition uncovers the vulnerabilities of BRG1 mutant tumor cells to DNA repair defects. In order to understand the mechanistic basis of the interactions between EZH2, BRG1 and TopoII, we propose to use a panel of human and mouse isogenic models in which the only difference is the presence or absence of BRG1. In Aim 1 we will identify mechanisms of DNA repair defects that occur with BRG1 deficiency in isogenic murine and human lung cancer cell lines by assessing markers of double strand break repair mechanisms, non- homologous end joining (NHEJ) and homologous recombination (HR). We will also determine if defects in DNA repair cause the sensitivity of BRG1 mutant lung tumors to dual EZH2i/etoposide treatment. In Aim 2 we will use mouse models to examine the preclinical effects of combination of EZH2 inhibition and etoposide against BRG1-null lung tumors. Genetically engineered mice and patient derived xenograft (PDX) models will be used to determine if the combination of EZH2 and TopoII inhibition is superior to standard of care therapies in place for BRG1-mutant lung cancers. In Aim 3 we will characterize the immune microenvironment of BRG1-deficient tumors and we will assess the impact of EZH2 inhibition with etoposide treatment on tumor immune cells. The potential impact of these studies is large because BRG1 is one of the most commonly mutated genes in NSCLC and there is currently no targeted therapy for this genetic subtype. In addition, EZH2 inhibitors have moved to Phase I trials for other tumor types, and the combination of EZH2 inhibition and orally bioavailable etoposide (VP-16) could rapidly move to trials if these preclinical studies suggest efficacy.

摘要/摘要 肺癌是全世界和美国癌症相关死亡的主要原因。这也是 遗传最复杂的疾病之一——非小细胞肺癌（NSCLC）的两种主要亚型， 肺鳞癌和肺腺癌的突变最多，分别排名第二和第三。 对 21 种不同肿瘤类型的研究中的 DNA 兆碱基。将这些突变映射到遗传区域的努力 已经证明 BRG1 相关因子 (BAF) 复合物（也称为 哺乳动物的 SWI/SNF 复合体很常见。编码 ATPase 的 BRG1 突变失活 BAF 复合物的解旋酶存在于 8-20% 的 NSCLC 中。 BRG1（也称为 SMARCA4）通常共同 KRAS 突变，目前尚无针对这种肺癌基因亚型的靶向治疗方法。 BAF 复合物长期以来被认为是含有 EZH2 的 Polycomb Repressive 的表观遗传拮抗剂 复合物 2 (PRC2)，但这些复合物在癌症环境中如何相互作用尚不清楚。 最近，我们证明 EZH2 抑制剂与拓扑异构酶 II (TopoII) 抑制剂具有良好的协同作用，例如 作为 BRG1 突变 NSCLC 中的依托泊苷。我们的数据表明 BRG1 在肺癌细胞中发挥着关键作用 涉及促进 TopoII 复合体功能。此外，我们的数据表明 EZH2 抑制的组合 TopoII 抑制揭示了 BRG1 突变肿瘤细胞对 DNA 修复缺陷的脆弱性。为了 为了了解 EZH2、BRG1 和 TopoII 之间相互作用的机制基础，我们建议使用 一组人类和小鼠同基因模型，其中唯一的区别是 BRG1 的存在或不存在。 在目标 1 中，我们将确定同基因小鼠中因 BRG1 缺陷而发生的 DNA 修复缺陷的机制 和人类肺癌细胞系，通过评估双链断裂修复机制的标记，非 同源末端连接（NHEJ）和同源重组（HR）。我们还将确定 DNA 是否存在缺陷 修复导致 BRG1 突变型肺肿瘤对 EZH2i/依托泊苷双重治疗敏感。在目标 2 中，我们将 使用小鼠模型来检查 EZH2 抑制和依托泊苷联合治疗的临床前效果 BRG1 缺失的肺部肿瘤。将使用基因工程小鼠和患者来源的异种移植（PDX）模型 确定 EZH2 和 TopoII 抑制的组合是否优于现有的标准护理疗法 用于 BRG1 突变型肺癌。在目标 3 中，我们将描述 BRG1 缺陷的免疫微环境 我们将评估依托泊苷治疗抑制 EZH2 对肿瘤免疫细胞的影响。这 这些研究的潜在影响很大，因为 BRG1 是最常见的突变基因之一 NSCLC，目前尚无针对这种基因亚型的靶向治疗。此外，EZH2 抑制剂还具有 进入其他肿瘤类型的 I 期试验，并将 EZH2 抑制与口服生物利用度相结合 如果这些临床前研究表明有效，依托泊苷 (VP-16) 可能会迅速进入试验阶段。