The role of the Kras4A isoform in epithelial carcinogenesis

描述(申请人提供)：大约30年前，RAS家族的基因在人类癌症中被发现发生突变，该项目的长期目标是加深对这些基因导致恶性转化的机制的理解。KRAS基因是最常见的突变家族成员，特别是在胰腺癌、结肠癌和肺癌中。这些肿瘤加在一起，每年在全世界造成数十万人死亡。利用基因工程小鼠模型，该实验室表明Kras的一个微小亚型(Kras4A)对于Kras突变肿瘤的发展是必不可少的。缺乏这种异构体的小鼠对Kras突变的肺部或皮肤肿瘤的发展具有高度的抵抗力，这表明抑制Kras4A的功能可能会为患者带来治疗益处。这个项目涉及到对由这种特定形式的Kras蛋白激活的信号通路的全面分析。许多新的方法将被用来理解Kras4A是如何在细胞和组织内发出信号的。最近开发的一种新的成像方法(光激活定位显微镜，或Palm)将成像Kras4A单分子在细胞中的位置，并找出突变的Kras4A蛋白和野生型Kras4A蛋白之间是否存在相互作用。在缺乏Kras4A或同时缺乏Kras4A和4B的细胞中，将研究通过典型的RAS通路组件进行的信号传递，以确定这些细胞中缺失的任何特定信号通路。最后，使用新的基因表达网络分析工具，将开发一个关于Kras信号在小鼠肺部活体的无偏见观点。比较易患肺癌的小鼠的基因表达网络和由于Kras4A缺失而产生抗性的小鼠的基因表达网络，可能会发现以前与RAS不相关的途径，这些途径可能解释了Kras4A在转化中的关键作用。利用小鼠体内模型，将研究Kras4A在干细胞损伤后再生肺上皮中的可能作用，并将开发新的模型，其中Kras4A可以被诱导的shRNA抑制，以研究该蛋白在携带突变的Kras基因的肿瘤的增殖和维持中的作用。

DESCRIPTION (provided by applicant): Genes of the RAS family were found to be mutated in human cancers around 30 years ago, and the long term goal of this project is to develop a deeper understanding of the mechanisms by which these genes cause malignant transformation. The KRAS gene is the most commonly mutated family member, particularly in carcinomas of the pancreas, colon and lung. Together, these tumors account for hundreds of thousands of deaths worldwide each year. Using genetically engineered mouse models, this laboratory showed that a minor isoform of Kras (Kras4A) is essential for development of Kras mutant tumors. Mice deficient in this isoform are highly resistant to development of lung or skin tumors with Kras mutations, suggesting that inhibition of the function of Kras4A could result in therapeutic benefit for patients. This project involves a comprehensive analysis of the signaling pathway that is activated by this specific form of the Kras protein. A number of novel approaches will be used to understand how Kras4A signals within cells and tissues. A recently developed new imaging approach (Photo-activated localization microscopy, or PALM) will image the location of single molecules of Kras4A in cells, and find out whether there is an interaction between mutant and wild type Kras4A proteins. Signaling through canonical RAS pathway components in cells lacking Kras4A or both Kras4A and 4B, will be investigated in order to identify any specific signaling pathways that are deficient in these cells. Finally, an unbiased view of Kras signaling in vivo in mouse lungs will be developed, using novel gene expression network analysis tools. Comparison of gene expression networks from mice that are susceptible to lung cancer with those that are resistant due to deletion of Kras4A may identify pathways not previously associated with Ras that may account for the critical role of Kras4A in transformation. Using mouse models in vivo, the possible function of Kras4A in regeneration of lung epithelium from stem cells after damage will be studied, and new models in which Kras4A can be inhibited using inducible shRNA will be developed to investigate the role of this protein in the propagation and maintenance of tumors with mutant Kras genes.