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: 7524320
• 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/7524320
• 关键词: Address; Binding; Cell Line; Cell Nucleus; Cells; Class; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; DNA Repair Pathway; DNA-PKcs; DNA-dependent protein kinase; Defect; Diagnosis; Disruption; 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; Numbers; Pathway interactions; Patients; Phenotype; Preparation; Protein Kinase Interaction; Public Health; 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; lung small cell carcinoma; mutant; nucleocytoplasmic transport; prevent; 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）：放射治疗，无论是单独或与化疗联合，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，放射治疗在NSCLC患者中并不总是有效的。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。我们最近发现了一个患者来源的非小细胞肺癌细胞系的子集，表现出显着的放射敏感性。这些NSCLC的一个一致特征是，它们都在EGFR的酪氨酸激酶结构域（TKD）中携带体细胞激活突变，这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。我们已经收集了多条证据支持突变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中存在缺陷，而且不能结合DNA依赖性蛋白激酶（DNA-PK）的催化和调节亚基。因此，具有TKD突变的EGFR的NSCLC在DNA双链断裂修复的修复中表现出显著延迟，并且响应于辐射的克隆形成存活率差。一个重要的发现是，TKD突变形式的EGFR的异位表达可以使具有不同遗传背景的不同细胞系放射增敏，包括KRAS和p53的放射防护突变。我们的研究已经确定了一个自然发生的EGFR突变的子集，消除了EGFR的关键辐射防护功能。我们将利用这些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在辐射诱导的DNA损伤修复中存在缺陷（2）检验EGFR酪氨酸激酶结构域突变阻断辐射诱导的EGFR核转位并损害DSB修复和克隆生存的假设（3）检验EGFR酪氨酸激酶结构域突变阻止辐射诱导的EGFR-DNA-PK相互作用并损害DSB修复和克隆生存的假设。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。公共卫生相关性：近75%的肺癌表现为非小细胞肺癌。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%。放疗是NSCLC患者的第一线治疗，有时也是唯一的一线治疗。然而，肿瘤对电离辐射的抗性对NSCLC的辐射控制提出了主要挑战。放射抗性肿瘤中有效的DNA修复途径经常被放射反应的分子决定因素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转运以及与DNA修复途径中的关键酶的相互作用。近期目标是阐明与EGFR酪氨酸激酶结构域（TKD）突变的生物学上不同的一类NSCLC相关的放射敏感性的潜在机制。长期目标是开发一种放射治疗策略，模拟TKD突变EGFR在NSCLC患者中的放射增敏作用。