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

描述（由申请人提供）：肺癌是一种非常常见、破坏性和知之甚少的疾病，在美国每年造成约160，000例死亡，在全球每年造成140万例死亡。尽管其患病率和惊人的高死亡率，疾病的起源仍然知之甚少，治疗肺癌患者的治疗方法已被证明是无效的。晚期肺癌患者的预后令人沮丧，这凸显了迫切需要新的化疗方法来治疗这种疾病。该研究计划的总体长期目标是帮助制定合理的治疗策略来治疗肺癌患者，完全雅阁国家癌症研究所的中心使命。本研究的近期目标是探讨Ras激活的RAF->MEK->ERK MAP激酶信号转导通路在肺癌发生、发展和治疗中的作用。由于在原发性患者标本和人肺癌衍生细胞系中观察到的编码EGF受体、KRAS或BRAF的基因突变的普遍性，该途径直接涉及肺癌细胞的异常生理学。这项拨款提案的中心假设是致癌KRasG 12 D或BRAfV 600 E可以通过激活RAF->MEK->ERK通路在人肺癌小鼠模型中启动和维持肿瘤发生。因此，我们将使用基因工程KRasLSL和BRafCA小鼠，其中癌基因表达是通过感染表达Cre重组酶的腺病毒在肺上皮中启动的，以深入探索致癌KRasG 12 D或BRafV 600 E在肺肿瘤发生、进展和治疗中的作用。在目标1中，我们将在KRasG 12 D和BRafV 600 E诱导的肺肿瘤发生之间进行头对头比较，以确定为什么前者进展为腺癌，而后者没有。接下来，为了测试RAF->MEK->ERK信号传导在KRasG 1/2 D诱导的肺肿瘤发生下游的重要性，我们将使用肺肿瘤发生的KRasLSL小鼠模型测试RAF（SB 590885）或MEK 1/2（PD 0325901）的有效、特异性和选择性药理学抑制剂的抗肿瘤作用。在目的2中，我们将使用小鼠以及人和小鼠肺癌衍生细胞系来检验以下假设：Ink 4a/Arf、Pten或Trp 53肿瘤抑制基因的缺失可以影响KRasG 12 D或BRafV 600 E诱导的肺肿瘤对RAF或MEK的药理学抑制的反应。最后，在目标3中，我们将利用我们最近衍生的BRAfFA小鼠，其中致癌BRAfV 600 E表达由Flp重组酶启动，以评估致癌基因激活和肿瘤抑制基因沉默的时间解离如何影响肿瘤的发生，进展和衰老。虽然这项建议主要集中在肿瘤抑制基因和癌基因作用对肿瘤生物学的作用以及肺癌小鼠模型中药物反应机制的研究，但这项研究在设计和评估治疗肺癌患者的新靶向策略方面具有潜在的重要转化意义。

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.