Mox 1: A Novel Mitogenic Oxidase

描述（由申请人提供）：nadph氧化酶Nox1产生活性氧（ROS），通过各种信号通路激活有丝分裂生长和血管生成。Nox1在60-70%的早期人类结肠癌中过表达，大量数据表明它在肿瘤发生中起作用。引入突变激活的K-Ras导致Nox1 mRNA的显著诱导，抗氧化剂和siRNA对Nox1的诱导可以阻止K-Ras诱导的细胞生长。我们提出，人类结肠癌中Nox1的过表达可能是由RasV12激活Nox1转录引起的。本课题拟在人类肿瘤样本中研究突变激活的K-Ras与Nox1过表达的相关性，并研究导致Nox1转录激活表达的信号通路。为了评估K-Ras致癌突变、Nox1过表达与肠道肿瘤之间的因果关系，我们建立了Nox1过表达和Nox1敲除小鼠。这些也将用于验证Nox1在由突变失活的APC和突变激活的K-Ras组成的遗传背景诱导的肠道肿瘤中起因果作用的假设。这些研究为Nox1作为治疗靶点提供了概念验证数据。在一个新提出的目标中，我们将使用药物化学方法来改善我们在高通量筛选Nox1调节蛋白过程中发现的Nox1抑制剂。提出了新的策略来提高亲和力和异构体选择性，从而开发单独靶向Nox1和Nox2的抑制剂。在最初的目标中，这些抑制剂将用于增强细胞生物学方法，并且还将评估它们作为nox导向药物的潜力。这些研究将提供关于Nox1在胃肠道癌症中的作用的新信息，并可能提供一种重要的新治疗方式。

DESCRIPTION (provided by applicant): The NADPH-oxidase Nox1 generates reactive oxygen species (ROS) that function through various signaling pathways to activate mitogenic growth and angiogenesis. Nox1 is overexpressed in ~ 60-70% of early human colon cancers, and considerable data point to a role in tumorigenesis. Introduction of mutationally activated K-Ras results in marked induction of Nox1 mRNA, and K-Ras-induced cell growth is prevented by antioxidants and by siRNA to Nox1. We propose that overexpression of Nox1 in human colon cancers can result from activation of Nox1 transcription by RasV12. This grant proposes to investigate the correlation of mutationally activated K-Ras and Nox1 overexpression in human tumor samples, and to investigate the signaling pathways leading to transcriptional activation of Nox1 expression. To evaluate the causal relationship between K-Ras oncogenic mutation, Nox1 overexpression, and intestinal neoplasia, Nox1 overexpressing and Nox1 knockout mice have been developed. These will also be used to test the hypothesis that Nox1 plays a causal role in intestinal tumors induced in a genetic background consisting of mutationally inactivated APC and mutationally activated K-Ras. These studies are providing proof-of-concept data for Nox1 as a therapeutic target. In a newly proposed aim, we will use medicinal chemistry approaches to improve inhibitors of Nox1 that we identified during high throughput screening of a Nox1 regulatory protein. Novel strategies are presented to improve affinity as well as isoform selectivity, so as to develop inhibitors that individually target Nox1 and Nox2. These inhibitors will be used to augment cell biological approaches in the original aims, and will also be evaluated for their potential as Nox-directed drugs. These studies will provide novel information regarding the role of Nox1 in GI cancers and may provide an important new treatment modality. PUBLIC HEALTH RELEVANCE: Free radicals that are made from oxygen have recently been found to be overproduced in several types of cancers, including those of the digestive tract. The major source of these radicals has recently been discovered to be a type of enzyme called a "Nox", and one of these, Nox1, is overproduced in colon cancer. This grant studies the way in which the gene for Nox1 is turned on to overproduce oxygen radicals and the role of these radicals as signals that cause cancer cells to divide and recruit new blood vessels. A new goal of the grant is to develop inhibitor molecules that will act on Nox1 to turn off the production of these free radicals. Such inhibitors will have potential in the treatment of several types of diseases, including cancer, cardiovascular diseases, and shock lung.