Role of EGFR in DNA Repair and Radiation Response in Non Small Cell Lung Cancer

EGFR 在非小细胞肺癌 DNA 修复和放射反应中的作用

• 批准号: 7825271
• 负责人: Chaitanya Suresh Nirodi
• 金额: $ 26.06万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7825271
• 关键词: Address; Binding; Cell Line; Cell Nucleus; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; DNA Repair Pathway; DNA-PKcs; DNA-dependent protein kinase; Defect; Diagnosis; Dose; Double Strand Break Repair; Ectopic Expression; Employee Strikes; Enzymes; Epidermal Growth Factor Receptor; Erlotinib; Exhibits; Gefitinib; Genetic; Goals; Ionizing radiation; KRAS2 gene; Kinetics; Link; Malignant Epithelial Cell; Malignant neoplasm of lung; Mediating; Molecular; Mutate; Mutation; Neoplasms; Non-Small-Cell Lung Carcinoma; Nonhomologous DNA End Joining; Nuclear Import; Nuclear Localization Signal; Nuclear Translocation; Pathway interactions; Patients; Phenotype; Preparation; Protein Kinase Interaction; Radiation; Radiation Induced DNA Damage; Radiation Tolerance; Radiation therapy; Radioprotection; Reagent; Reporting; Resistance; Role; Simulate; Site; Survival Rate; TP53 gene; Testing; Tyrosine Kinase Domain; Tyrosine Kinase Inhibitor; chemotherapy; lung Carcinoma; mutant; nucleocytoplasmic transport; prevent; public health relevance; receptor; receptor binding; repaired; response; small molecule; tool; tumor

DESCRIPTION (provided by applicant): Radiotherapy, either alone, or in combination with chemotherapy, is frequently used in the treatment of patients with non-small cell lung carcinoma. However, tumor responses to ionizing radiation vary considerably and radiotherapy is not always effective in NSCLC patients. The epidermal growth factor receptor is an important determinant of radioresponse, whose elevated expression and activity frequently correlates with radioresistance in NSCLC tumors. We recently identified a subset of patient- derived NSCLC cell lines that exhibit marked sensitivity to radiation. A consistent feature among these NSCLCs is that they all harbor somatic, activating mutations in the tyrosine kinase domain (TKD) of the EGFR, that have also been linked to tumor sensitivity to small molecule tyrosine kinase inhibitors, gefitinib and erlotinib. We have assembled multiple lines of evidence that support a potential mechanism underlying mutant EGFR-associated radiosensitivity. The evidence reveals that, unlike the wild type EGFR, receptors with activating mutations in the TKD are not only defective in radiation- induced translocation to the nucleus but also fail to bind the catalytic and regulatory subunits of the DNA-dependent protein kinase (DNA-PK). Consequently, NSCLCs with TKD-mutated EGFR exhibit significant delays in the repair of DNA double strand break repair and poor clonogenic survival in response to radiation. A crucial finding is that ectopic expression of TKD-mutated forms of EGFR can radiosensitize different cell lines with diverse genetic backgrounds, including radioprotective mutations in KRAS and p53. Our study has identified a subset of naturally occurring EGFR mutations that abrogate a critical radioprotective function of EGFR. We will use these as tools to address three specific aims of our proposal: (1) To confirm that NSCLCs with mutations in the tyrosine kinase domain of EGFR are defective in repair of radiation-induced DNA damage (2) To test the hypothesis that mutations in the tyrosine kinase domain of EGFR block radiation-induced nuclear translocation of EGFR and compromise DSB repair and clonogenic survival (3) To test the hypothesis that mutations in the tyrosine kinase domain of EGFR prevent radiation-induced EGFR-DNA-PK interactions and compromise DSB repair and clonogenic survival. The long term goal is to develop a molecular rationale for a radiotherapeutic strategy in NSCLC patients that simulates the radiosensitizing effects of TKD- mutated EGFR. Public Health Relevance: Nearly 75% of all lung cancers manifest as non-small lung carcinoma. The median five-year survival rate for patients diagnosed with non-small lung cancer (NSCLC) is estimated at barely 14%. Radiotherapy is the first and sometimes only line of treatment for patients with NSCLCs. However, tumor resistance to ionizing radiation presents a major challenge to radiotherapeutic control of NSCLCs. Efficient DNA repair pathways in radioresistant tumors are frequently augmented by molecular determinants of radioresponse such as the epidermal growth factor receptor (EGFR). One of the critical radioprotective functions of EGFR involves radiation induced nuclear transport and interactions with key enzymes in DNA repair pathways. The immediate objective is to elucidate mechanisms underlying the radiosensitivity associated with a biologically distinct class of NSCLCs that harbor mutations in the tyrosine kinase domain (TKD) of EGFR. The long term goal is to develop a radiotherapeutic strategy that simulates the radiosensitizing effects of TKD-mutated EGFR in NSCLC patients.

描述（由申请人提供）：放射疗法，无论是单独使用，还是与化疗联合使用，经常用于治疗非小细胞肺癌患者。然而，肿瘤对电离辐射的反应差异很大，放疗对 NSCLC 患者并不总是有效。表皮生长因子受体是放射反应的重要决定因素，其表达和活性升高通常与 NSCLC 肿瘤的放射抗性相关。我们最近鉴定了一个源自患者的 NSCLC 细胞系子集，它们对辐射表现出明显的敏感性。这些 NSCLC 的一个一致特征是，它们都在 EGFR 酪氨酸激酶结构域 (TKD) 中存在体细胞激活突变，这些突变也与肿瘤对小分子酪氨酸激酶抑制剂吉非替尼和厄洛替尼的敏感性有关。我们收集了多种证据，支持突变型 EGFR 相关放射敏感性的潜在机制。证据表明，与野生型 EGFR 不同，TKD 中具有激活突变的受体不仅在辐射诱导的细胞核易位方面存在缺陷，而且无法结合 DNA 依赖性蛋白激酶 (DNA-PK) 的催化和调节亚基。因此，具有 TKD 突变 EGFR 的 NSCLC 在 DNA 双链断裂修复方面表现出显着延迟，并且响应辐射的克隆存活率较差。一个重要的发现是，TKD 突变形式的 EGFR 异位表达可以使具有不同遗传背景的不同细胞系放射敏感，包括 KRAS 和 p53 的放射防护突变。我们的研究已经确定了自然发生的 EGFR 突变的子集，这些突变消除了 EGFR 的关键放射防护功能。我们将使用这些作为工具来实现我们提案的三个具体目标：(1) 确认 EGFR 酪氨酸激酶结构域突变的 NSCLC 在修复辐射诱导的 DNA 损伤方面存在缺陷 (2) 检验 EGFR 酪氨酸激酶结构域突变阻断辐射诱导的 EGFR 核易位并损害 DSB 修复和克隆存活的假设 (3) 检验以下假设：EGFR 酪氨酸激酶结构域的突变可阻止辐射诱导的 EGFR-DNA-PK 相互作用并损害 DSB 修复和克隆存活。长期目标是为 NSCLC 患者的放射治疗策略开发分子原理，模拟 TKD 突变 EGFR 的放射增敏作用。公共健康相关性：所有肺癌中近 75% 表现为非小肺癌。诊断为非小细胞肺癌 (NSCLC) 的患者的中位五年生存率估计仅为 14%。放射治疗是非小细胞肺癌患者的首选治疗方法，有时也是唯一的治疗方法。然而，肿瘤对电离辐射的抵抗对非小细胞肺癌的放射治疗控制提出了重大挑战。放射抗性肿瘤中的有效 DNA 修复途径经常被放射反应的分子决定因素（例如表皮生长因子受体 (EGFR)）增强。 EGFR 的关键辐射防护功能之一涉及辐射诱导的核运输以及与 DNA 修复途径中关键酶的相互作用。近期目标是阐明与一类生物学上不同的 NSCLC 相关的放射敏感性的潜在机制，这些 NSCLC 中存在 EGFR 酪氨酸激酶结构域 (TKD) 突变。长期目标是开发一种放射治疗策略，模拟 NSCLC 患者中 TKD 突变 EGFR 的放射增敏作用。