Novel mechanisms of oncogenic transformation in lung cancer

描述(申请人提供)：在美国，死于肺癌的人数比死于乳腺癌、前列腺癌和结肠癌的总和还要多。特定的癌基因，如信号GTPase KRAS的生长因子，在肺癌中发生突变并具有结构性活性。尽管癌基因蛋白可以推动肺癌的发展，但对导致这一过程以及肺癌的发生和发展的分子和遗传事件尚不完全了解。MicroRNA(MiRNA)是一种调节蛋白质表达的非编码RNA，与参与肿瘤发生和发展的细胞过程有关。我们推测，在肺癌中过度表达的特定miRNA可能作为癌基因本身发挥作用，或者与已知的癌基因协同作用，启动肺癌的发生。为了确定特定的miRNA在肺腺癌中是否具有致癌作用，我们研究了miRNA的表达。在肺腺癌中检测到特定miRNA水平的变化，其中一种特定miRNA在一组肺腺癌细胞系中过表达，该细胞系也包含KRAS的激活突变。值得注意的是，在人类肺腺癌患者样本中检测到这种miRNA水平升高，这与疾病分期有关。这种miRNA在未转化的人肺上皮细胞中过表达导致了增殖和非锚定生长的增加。在人肺腺癌细胞中抑制这种miRNA可以抑制异种移植模型中的增殖和过表达诱导的肿瘤形成。重要的是，在一种新产生的小鼠模型中，这种miRNA在肺部的可诱导表达迅速导致了增生和腺瘤的发展。我们还发现了多个RAS信号通路的负调控因子作为这个miRNA的靶标。因此，我们假设这个miRNA是通过调节RAS癌信号通路而启动肺腺癌的一个新的驱动因素，并且它与突变的KRAS在肺癌的发生发展中具有协同作用。我们建议用三个具体的目标来检验这一假设。在目标1中，我们将使用新的肺特异性可诱导miRNA小鼠来评估这种miRNA表达增加在肺癌发生中的作用及其在突变的KRAS驱动的肺癌中的作用。在目标2中，我们将研究致癌RAS途径的负调控因子作为特定miRNA的靶点，并寻找在腺癌发生和发展过程中导致肺早期和晚期变化的新靶点。在目标3中，我们将确定人类肺癌中的基因突变以及调节这种miRNA表达的信号通路。在这一应用中提出的小鼠模型、患者样本、分子生物学、生物化学和细胞生物学的集成将显著增加对miRNA在肺腺癌中的作用以及导致这种致命疾病的分子事件的理解。这些研究的结果也可能确定肺腺癌的新治疗靶点和诊断和预后标记物。

DESCRIPTION (provided by applicant): More people in the US die from lung cancer than from breast, prostate and colon cancer combined. Specific oncogenes, such as the growth factor signaling GTPase KRAS, are mutated and constitutively active in lung cancers. Although it is clear oncogenic proteins can drive lung cancer development, there is incomplete understanding of the molecular and genetic events that result in this process and in the initiation and progression of lung cancers. microRNA (miRNA), non-coding RNA that regulate protein expression, have been linked to cellular processes involved in tumor development and progression. We postulated that specific miRNA that are overexpressed in lung cancer may function as oncogenes themselves or cooperate with known oncogenes in the initiation of this malignancy. To determine whether specific miRNA have an oncogenic role in lung adenocarcinoma, the most common lung cancer, we investigated miRNA expression. Altered levels of specific miRNA were detected in lung adenocarcinoma, and one particular miRNA was overexpressed in a panel of lung adenocarcinoma cells lines that also contained activating mutations of KRAS. Notably, elevated levels of this miRNA were detected in human lung adenocarcinoma patient samples and this correlated with disease stage. Overexpression of this miRNA in untransformed human lung epithelial cells resulted in increased proliferation and anchorage-independent growth. Inhibition of this miRNA in human lung adenocarcinoma cells suppressed proliferation and overexpression induced tumor formation in a xenograft model. Importantly, in a novel, newly generated mouse model, inducible expression of this miRNA in the lungs rapidly led to hyperplasia and adenoma development. We have also identified multiple negative regulators of RAS pathway signaling as targets of this miRNA. Therefore, we hypothesize this miRNA is a novel driver of lung adenocarcinoma initiation through modulation of the RAS oncogenic signaling pathway and that it cooperates with mutant KRAS in lung cancer development. We propose to test this hypothesis with three Specific Aims. In Aim 1, we will use the novel lung specific inducible miRNA mouse to evaluate the effects of increased expression of this miRNA on lung cancer initiation and its contribution to mutant KRAS-driven lung cancer. In Aim 2, we will investigate the negative regulators of the oncogenic RAS pathway as targets of the specific miRNA, and we will identify novel targets that contribute to early and late changes in the lung during adenocarcinoma initiation and progression. In Aim 3, we will determine the genetic mutations in human lung cancer and the signaling pathways that regulate the expression of this miRNA. The integration of mouse models, patient samples, molecular biology, biochemistry, and cell biology proposed in this application will significantly increase understanding of the contribution of miRNA to lung adenocarcinoma and the molecular events that lead to the initiation of this deadly disease. Results from these studies are also likely to identify novel therapeutic targets and diagnostic and prognostic markers for lung adenocarcinoma.