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的、毁灭性的、鲜为人知的疾病，在美国每年造成约16万人死亡，在全球每年造成140万人死亡。尽管它的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令人失望的无效。晚期肺癌患者的惨淡预后强调了迫切需要新的化疗方法来治疗这种疾病。这个研究项目的首要和长期目标是帮助开发合理的治疗策略来治疗肺癌患者，这完全符合国家癌症研究所的中心使命。然而，本提案的直接目的是探索ras激活的RAF->MEK->ERK MAP激酶信号转导通路在肺癌的发生、进展和治疗中的作用。由于在原发性患者标本和人肺癌衍生细胞系中观察到编码EGF受体、KRAS或BRAF的基因突变的普遍存在，该途径直接与肺癌细胞的异常生理有关。本课题的中心假设是，致癌基因KRasG12D或BRafV600E可以通过激活RAF->MEK->ERK通路，在人肺癌小鼠模型中启动并维持肿瘤发生。因此，我们将利用基因工程KRasLSL和BRafCA小鼠，通过感染表达Cre重组酶的腺病毒在肺上皮中启动癌基因表达，深入探索致癌KRasG12D或BRafV600E在肺肿瘤的发生、发展和治疗中的作用。在Aim 1中，我们将对KRasG12D-和brafv600e诱导的肺肿瘤发生进行正面比较，以确定为什么前者进展为腺癌，而后者不会。接下来，为了测试RAF->MEK->ERK信号在krasg12d诱导的肺肿瘤发生下游的重要性，我们将使用KRasLSL小鼠肺肿瘤发生模型测试RAF （SB590885）或MEK1/2 （PD0325901）的强效、特异性和选择性药理抑制剂的抗肿瘤作用。在Aim 2中，我们将使用小鼠、人和小鼠肺癌衍生细胞系测试Ink4a/Arf、Pten或Trp53肿瘤抑制基因的缺失会影响KRasG12D-或brafv600e诱导的肺肿瘤对RAF或MEK药理学抑制的反应。最后，在Aim 3中，我们将利用我们最近获得的BRafFA小鼠，其中致癌BRafV600E表达是由Flp重组酶启动的，来评估癌基因激活的时间解离和肿瘤抑制基因沉默如何影响肿瘤的发生、进展和衰老。虽然本研究主要关注肿瘤抑制因子和癌基因在肿瘤生物学中的作用以及肺癌小鼠模型中药物反应机制的研究，但本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。公共卫生相关性：肺癌是一种非常常见的、毁灭性的、鲜为人知的疾病，在美国每年造成约16万人死亡，在全世界每年造成140万人死亡。在这里，我们建议使用复杂的基因工程小鼠癌症模型和新的靶向药物细胞信号通路抑制剂来探索肿瘤抑制因子和癌基因在肺癌发生、进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.