Molecular dissection of pancreatic ductal adenocarcinoma

胰腺癌是美国癌症相关死亡率的主要原因， 每年有32,000人死亡。KRAS 2癌基因的激活突变，AKT 2癌基因的扩增， 以及TP 53、INK 4A和MADH 4肿瘤抑制基因的缺失，通常发生在这种疾病中。然而，在这方面， 由于这些遗传变化而发生的精确信号扰动仍然很差， 明白例如，尽管KRAS 2癌基因中的激活突变发生在大约90%的人中， 胰腺导管腺癌，各种Ras刺激信号的相对贡献 途径  由Raf、PI 3-激酶和RalGEF介导的蛋白质与疾病的发病机制的关系尚不清楚。 因此，本申请描述了胰腺导管腺癌的新型小鼠模型的用途 （PDAC），通过将编码癌基因的鸟类逆转录病毒体细胞导入到体内而产生 表达禽逆转录病毒受体TVA的转基因小鼠的胰腺， 导管上皮，以确定K-Ras刺激的信号通路对肿瘤起始的相对贡献， 维持和进步。 该建议旨在回答以下问题：1）躯体和精神疾病的后果是什么？ 胰腺导管上皮细胞中Ras信号的零星激活？2)不同的角色是什么 Ras激活的PDAC信号通路？和3）与哪些基因相关的基因表达特征 胰腺肿瘤中Ras调节的信号通路的激活？ 确定胰腺导管上皮细胞（PDEC）中Kras基因激活的直接后果 以及单个下游效应子途径、编码激活的Kras等位基因的病毒或 Kras等位基因，优先导致激活个别下游途径，将被引入到 PDECs和对细胞增殖和凋亡的影响。此外，肿瘤将在体内诱导 通过将编码K-Ras或K-Ras效应突变体的病毒引入TVA转基因小鼠的胰腺中， 小鼠，并通过组织学、免疫染色和生化方法分析肿瘤表型。 此外，通过使用小分子抑制剂和RNA干扰方法， 持续肿瘤细胞增殖和存活的特异性Ras刺激信号通路将被 确立了习最后，将进行基因表达谱分析以鉴定：（i）基因表达变化 与K-Ras介导的胰腺导管上皮细胞转化的早期步骤相关;（ii）A基因 与K-Ras诱导的胰腺导管肿瘤相关的表达特征;和（iii）基因表达 与特定Ras刺激的下游通路的激活相关的特征。这样的基因 表达签名可以潜在地用作诊断工具，以及响应的替代标记。 有针对性的治疗干预。胰腺癌每年夺去32，000名美国人的生命;因此了解其机制 导致这种疾病的发生和发展是至关重要的。通过使用小说 胰腺癌的小鼠模型，本申请旨在了解激活Kras的后果 胰腺导管上皮细胞中的基因突变，以及介导这些效应的下游途径。 这些研究将显著提高对胰腺癌的认识，并可能导致 开发新的治疗策略，从而减少这种疾病对公共卫生的影响。

Pancreatic cancer is a leading cause of cancer-related mortality in the United States with an estimated 32,000 deaths annually. Activating mutations in the KRAS2 oncogene, amplification of the AKT2 oncogene, and loss of the TP53, INK4A, and MADH4 tumor suppressor genes, commonly occur in this disease. However, the precise signaling perturbations that occur as a consequence of these genetic changes are still poorly understood. For example, although activating mutations in the KRAS2 oncogene occur in approximately 90% of pancreatic ductal adenocarcinomas, the relative contributions of the various Ras-stimulated signaling pathways  mediated by Raf, PI3-kinase, and RalGEFs - to the pathogenesis of the disease are unknown. Therefore, this application describes the use of a novel mouse model for pancreatic ductal adenocarcinoma (PDAC), generated through the somatic introduction of oncogene-encoding avian retroviruses into the pancreata of transgenic mice expressing the avian retroviral receptor, TVA, specifically within the pancreatic duct epithelium, to identify the relative contributions of K-Ras-stimulated signaling pathways to tumor initiation, maintenance, and progression. This proposal seeks to answer the following questions: 1) What are the consequences of somatic and sporadic activation of Ras signaling in the pancreatic duct epithelium? 2) What are the roles of the various Ras-activated signaling pathways in PDAC? And 3) What are the gene expression signatures associated with the activation of Ras-regulated signaling pathways in pancreatic tumors? To identify the immediate consequences of Kras gene activation in pancreatic duct epithelial cells (PDECs) and the roles played by individual downstream effector pathways, viruses encoding an activated Kras allele, or Kras alleles that preferentially lead to the activation of individual downstream pathways, will be introduced into PDECs and the effect on cell proliferation and apoptosis determined. In addition, tumors will be induced in vivo by the introduction of viruses encoding K-Ras or K-Ras effector mutants into the pancreata of TVA transgenic mice, and the tumor phenotypes analyzed by histology, immunostaining and biochemical methods. Furthermore, through the use of small molecule inhibitors and RNA interference methods, the requirement for specific Ras-stimulated signaling pathways for sustained tumor cell proliferation and survival will be established. Finally, gene expression profiling will be performed to identify: (i) Gene expression changes associated with the early steps of K-Ras-mediated transformation of pancreatic duct epithelial cells; (ii) A gene expression signature associated with K-Ras-induced pancreatic ductal tumors; and (iii) Gene expression signatures associated with the activation of specific Ras-stimulated downstream pathways. Such gene expression signatures may potentially be used as diagnostic tools, as well as surrogate markers for response to targeted therapeutic interventions. Pancreatic cancer claims the lives of 32,000 Americans annually; therefore understanding the mechanisms that contribute to the initiation and progression of this disease is of vital importance. Through the use of a novel mouse model for pancreatic cancer, this application seeks to understand the consequences of activating Kras gene mutations in pancreatic duct epithelial cells, and the downstream pathways that mediate these effects. These studies will significantly enhance the understanding of pancreatic cancer, and may lead to the development of novel therapeutic strategies, thereby reducing the impact of this disease on public health.