Project 4: NOX1 Involvement In Colon Cancer

NOX1氧化应激、RAS与结肠癌 NADPH-氧化酶Nox1产生活性氧(ROS)，通过信号转导发挥作用 激活有丝分裂生长和血管生成的途径。Nox1在早期人类中过表达-60%-70% 结肠癌，与肿瘤发生中的作用一致。基于细胞模型研究，我们假设 人类结肠癌中Nox1的过度表达可能是由激活的KRAS诱导Nox1转录所致。 人类肠道肿瘤与对照组织的特征将确定Nox1 过表达与K-RAS的致癌突变和/或肿瘤中的失活突变有关 抑制基因P53和ARC。肿瘤中Nox1过度表达与NFkappaB的关系 生长相关信号通路(MARK、PI3-)的激活、COX2过表达和激活 也将对其进行评估。直接评价K-RAS致癌因素之间的因果关系 突变、Nox1过表达和肠癌，我们之前发现Nox1过表达和 Nox1基因敲除小鼠。将Villin K-RasV12小鼠与Nox1基因敲除和Nox1过表达的小鼠杂交 动物，我们将测试Nox1是否介导V12-RAS导向的肿瘤发生。通过调查Nox1 肿瘤抑制基因(P53和ARC)的表达、突变和生长相关信号的激活 在肿瘤和邻近正常组织中的信号转导途径(Akt/PKB、ERK1、2、JNK)，我们将确定分子事件 与肿瘤的发生和发展有关。Nox1调节有丝分裂生长的机制将 通过评估核因子-kappaB的激活和COX2的诱导/激活来进一步研究。我们会 与其他项目合作评估Nox1在诱导DNA损伤反应中的作用 肿瘤的启动/进展途径。我们还将调查NOX1衍生的ROS的假设 通过抑制蛋白酪氨酸磷酸酶刺激有丝分裂生长，导致酪氨酸增加 重要的促有丝分裂调节蛋白的磷酸化水平。这些研究将为我们提供新的 关于Nox1在胃肠癌中的作用及其与肿瘤基因突变的关系的信息 K-RAS，以及RAS和NOX1利用的促有丝分裂信号系统。

Nox1 Oxidant Stress, Ras And Colon Cancer" The NADPH-oxidase Nox1 generates reactive oxygen species (ROS) that function through signaling pathways to activate mitogenic growth and angiogenesis. Nox1 is overexpressed in -60-70% of early human colon cancers, consistent with a role in tumorigenesis. Based on cell model studies, we hypothesize that Nox1 overexpression in human colon cancers can result from induction of Nox1 transcription by activated KRas. Human intestinal tumors vs. control tissue will be characterized to establish whether Nox1 overexpression is linked to oncogenic mutations in K-Ras and/or to inactivating mutations in the tumor suppressors p53 and ARC. The extent to which Nox1 overexpression in tumors is associated with NFkappaB activation, Cox2 overexpression and activation of growth-related signaling pathways (MARK, PI 3- kinase) will also be evaluated. To evaluate directly the causal relationships among K-Ras oncogenic mutation, Nox1 overexpression, and intestinal cancer, we previously developed Nox1-overexpressing and Nox1 -knockout mice. By crossing villin K-RasV12 mice with Nox1-knockout and Nox1-overexpressing animals, we will test whether Nox1 mediates V12-Ras-directed tumorigenesis. By investigating Nox1 expression, mutation of tumor suppressors (p53 and ARC) and activation of growth-associated signaling pathways (Akt/PKB, ERK1,2, JNK) in tumors and adjacent normal tissue, we will determine molecular events relevant to tumor initiation and progression. The mechanisms by which Nox1 regulates mitogenic growth will be further investigated by evaluating activation of NF-kappaB and the induction/activation of Cox2. We will evaluate collaboratively with other projects the role of Nox1 in the induction of the DNA damage response in the tumor initiation/progression pathway. We will also investigate the hypothesis that Nox1-derived ROS stimulates mitogenic growth by inhibiting protein tyrosine phosphatases, leading to a increased tyrosine phosphorylation levels of important mitogenic regulatory proteins. These studies will provide novel information regarding the role of Nox1 in gastrointestinal cancers, its relationship to oncogenic mutations in K-Ras, and the mitogenic signaling systems utilized by Ras and Nox1.