Studying the initiation, progression and therapy of lung cancer in mouse models

描述(申请人提供)：肺癌是一种极其常见、破坏性极强、且知之甚少的疾病，每年在美国造成约16万人死亡，在全球每年导致140万人死亡。尽管它的发病率和惊人的高死亡率，疾病的起源仍然鲜为人知，治疗肺癌患者的治疗方法被证明令人失望地无效。晚期肺癌患者悲惨的预后强调了迫切需要新的化疗方法来治疗这种疾病。这项研究计划的总体、长期目标是帮助开发合理的治疗策略来治疗肺癌患者，这与国家癌症研究所的中心使命完全一致。然而，这项建议的近期目标是探讨RAS激活的RAF-&GT；MEK-&GT；ERK-MAP-KK信号转导通路在肺癌的发生、发展和治疗中的作用。由于在原发患者标本和人肺癌细胞系中观察到编码EGF受体、KRAS或BRAF的基因突变，这一途径直接与肺癌细胞的异常生理有关。这项拨款提案的中心假设是致癌的KrasG12D或BRafV600E可以通过激活RAF-&GT；MEK-&GT；ERK途径来启动和维持人类肺癌小鼠模型的肿瘤形成。因此，我们将使用基因工程KRasLSL和BRafCA小鼠，其中癌基因的表达是通过感染表达Cre重组酶的腺病毒在肺上皮细胞中启动的，以深入探讨致癌基因KrasG12D或BRafV600E在肺癌发生、发展和治疗中的作用。在目标1中，我们将对KrasG12D和BRafV600E诱导的肺肿瘤形成进行面对面的比较，以确定前者进展为腺癌而后者不进展为腺癌的原因。接下来，为了测试RAF-&GT；MEK-&GT；ERK信号在KrasG12D诱导的肺肿瘤形成过程中的重要性，我们将使用KRasLSL小鼠肺肿瘤形成模型来测试有效的、特异的和选择性的药物抑制剂RAF(SB590885)或MEK1/2(PD0325901)的抗肿瘤效果。在目标2中，我们将使用小鼠以及人和小鼠肺癌衍生细胞株来验证Ink4a/Arf、Pten或Trp53抑癌基因的缺失可以影响KrasG12D或BRafV600E诱导的肺癌对RAF或MEK的药理抑制的反应的假设。最后，在目标3中，我们将利用我们最近衍生的BRafFA小鼠，在其中致癌基因BRafV600E的表达是由FLP重组酶启动的，以评估癌基因激活和肿瘤抑制基因沉默的时间分离如何影响肿瘤的启动、进展和衰老。虽然这项建议主要集中在肿瘤抑制和癌基因作用在肿瘤生物学中的作用以及在小鼠肺癌模型中药物反应的机制的研究，但这项研究在设计和评估新的靶向治疗肺癌患者的策略方面具有潜在的重要翻译意义。与公共卫生相关：肺癌是一种非常常见、破坏性很强的疾病，在美国每年造成约16万人死亡，全球每年导致140万人死亡。在这里，我们建议使用先进的基因工程小鼠癌症模型和新的靶向药物抑制细胞信号通路，以探索肿瘤抑制基因和癌基因在肺癌发生、发展和治疗中的重要性。这些实验的长期目标是开发新的、合理设计的策略，以更有效地治疗肺癌患者。

DESCRIPTION (provided by applicant): Lung cancer is an extraordinarily common, devastating and poorly understood disease responsible for ~160,000 deaths/year in the USA and 1.4 million deaths/year worldwide. Despite its prevalence and strikingly high mortality rates, the origins of the disease remain poorly understood and therapeutic approaches to treat lung cancer patients have proven disappointingly ineffective. The dismal prognosis for patients with advanced lung cancer emphasizes the urgent need for new chemotherapeutic approaches to treat this disease. The overarching, long-term goal of this research program is to aid development of rational therapeutic strategies to treat lung cancer patients, in full accord with the central mission of the National Cancer Institute. However, the immediate objective of this proposal is to explore the role of the Ras-activated RAF->MEK->ERK MAP kinase signal transduction pathway in the initiation, progression and therapy of lung cancer. This pathway is directly implicated in the aberrant physiology of lung cancer cells due to the prevalence of mutations in genes encoding the EGF receptor, KRAS or BRAF observed in primary patient specimens and human lung cancer derived cell lines. The central hypothesis of this grant proposal is that oncogenic KRasG12D or BRafV600E can initiate and maintain tumorigenesis in mouse models of human lung cancer through activation of the RAF->MEK->ERK pathway. Consequently we shall use genetically engineered KRasLSL and BRafCA mice, in which oncogene expression is initiated in the lung epithelium by infection with an adenovirus expressing Cre recombinase, to conduct an in-depth exploration of the role of oncogenic KRasG12D or BRafV600E in lung tumor initiation, progression and therapy. In Aim 1 we will conduct a head-to-head comparison between KRasG12D- and BRafV600E-induced lung tumorigenesis to determine why the former progresses to adenocarcinoma while the latter does not. Next, to test the importance of RAF->MEK->ERK signaling downstream of KRasG12D-induced lung tumorigenesis, we will test the anti-tumor effects of potent, specific and selective pharmacological inhibitors of either RAF (SB590885) or MEK1/2 (PD0325901) using the KRasLSL mouse model of lung tumorigenesis. In Aim 2 we will test the hypothesis that the loss of the Ink4a/Arf, Pten or Trp53 tumor suppressor genes can influence the response of KRasG12D- or BRafV600E-induced lung tumors to pharmacological inhibition of RAF or MEK using mice, and human and mouse lung cancer derived cell lines. Finally, in Aim 3, we will utilize our recently derived BRafFA mice, in which oncogenic BRafV600E expression is initiated by Flp recombinase, to assess how temporal dissociation of oncogene activation and tumor suppressor gene silencing influences tumor initiation, progression and senescence. Although this proposal is focused primarily on studies of the role of tumor suppressor and oncogene action on tumor biology and on mechanisms of drug response in mouse models of lung cancer, this research has potentially important translational significance in the design and evaluation of new targeted strategies to treat lung cancer patients. PUBLIC HEALTH RELEVANCE: Lung cancer is a remarkably common, devastating and poorly understood disease responsible for ~160,000 deaths/year in the USA and 1.4 million deaths/year worldwide. Here, we propose the use of sophisticated genetically engineered mouse models of cancer and new targeted pharmacological inhibitors of cell signaling pathways to explore the importance of tumor suppressors and oncogenes in lung cancer initiation, progression and therapy. The long-term goal of these experiments is the development of new and rationally designed strategies to more effectively treat lung cancer patients.