Genetic dissection of oncogenic RAS-driven tumor initiation in vivo

项目摘要/摘要 RAS家族由KRAS、NRAS和HRAS组成，是人类最常见的突变癌基因 癌症。尽管有50多种可能的致癌RAS突变，但每种癌症类型都有特定的和 通常是这些突变的唯一子集。RAS突变通常发生在肿瘤发生的早期，如果不是 作为启动突变，这些突变模式反映了潜在的基础生物学过程 肿瘤的起源。因此，阐明导致RAS突变模式的机制将解决 癌症生物学中的一个基本问题--癌症是如何起源的。鉴于此，最能提供信息的方法是 询问这些模式是为了研究RAS突变何时在活体内的正常细胞中首次发生 布景。试图追溯到从一个发起突变的细胞中捕获一个基因中的一个随机突变事件 癌症在表现为一种疾病之前几十年对人类来说是具有挑战性的。然而，有两只小鼠 允许精确定义启动RAS突变的模型系统，因此可以进行研究 RAS突变模式。一是致癌，这特别适合于询问突变是如何发生的 这一过程产生了RAS突变模式。突变等位基因在空间和空间上的遗传激活 时间受限的方式，这是理想的研究正常细胞中已定义的RAS突变的反应。我们 因此建议利用这两种不同模型的各自优势来阐明其机制 通过这种突变模式，在体内肿瘤形成的一开始，正常细胞中就建立了RAS突变模式。 具体地说，在目标1中，我们将通过监测突变来确定特定的ras突变是如何产生肿瘤的。 在致癌物暴露后立即发生，此后在改变RAS突变模式的遗传背景中发生。 在目标2中，我们将确定不同正常细胞在遗传诱导下的信号和细胞反应。 不同致癌基因的RAS突变体。因此，这项建议的完成将阐明 在人类癌症中选择特定的RAS突变，以及更广泛地说，癌症是如何起源的，这已经 早期发现和预防的临床意义。

PROJECT SUMMARY/ABSTRACT The RAS family comprised of KRAS, NRAS, and HRAS are the most commonly mutated oncogenes in human cancer. Despite there being over 50 possible oncogenic RAS mutations, each cancer type has a specific and often unique subset of these mutations. As RAS mutations typically occur early during tumorigenesis, if not being the initiating mutation, these mutational patterns reflect fundamental biology underlying the process of tumor initiation. Elucidating the mechanisms giving rise to RAS mutation patterns would therefore address a foundational question in cancer biology- how cancer originates. Given this, the most informative approach to interrogate these patterns is to study RAS mutations when they 1) first occur in 2) normal cells in an 3) in vivo setting. Trying to backtrack to catch that one random mutagenic event in one gene from one cell that initiates cancer decades before manifesting as a disease is challenging in humans. There are, however, two murine model systems that allow an initiating RAS mutation to be precisely defined, and hence are amenable to studying RAS mutation patterns. One, carcinogenesis, which is particularly well suited to interrogate how the mutagenic process gives rise to RAS mutation patterns. Two, genetic activation of mutant alleles in a spatially and temporally restricted fashion, which is ideal to study the response of defined Ras mutations in normal cells. We thus propose to capitalize on the individual strengths of these two different models to elucidate the mechanisms by which RAS mutation patterns are laid down in normal cells at the very onset of tumorigenesis in vivo. Specifically, in aim 1 we will determine how tumors arise by a specific Ras mutation by monitoring mutagenesis immediately after carcinogen exposure and thereafter in genetic backgrounds that alter RAS mutation patterns. In aim 2 we will determine the signaling and cellular responses of different normal cells upon genetic induction of different oncogenic Ras mutants. Completion of this proposal will thus elucidate the principles underlying the selection for specific RAS mutations in human cancers, and more broadly, how cancers originate, which has clinical implications for early detection and prevention.