NADPH oxidase 1 plays a critical mediating role in oncogenic Ras-induced vascular endothelial growth factor expression
NADPH oxidase 1 plays a critical mediating role in oncogenic Ras-induced vascular endothelial growth factor expression
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DOI：
10.1038/onc.2008.102
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发表时间：
2008-08-01
期刊：
影响因子：
8
通讯作者：
Kamata, T.
中科院分区：
文献类型：
--
作者：
Komatsu, D.;Kato, M.;Kamata, T.
活性氧簇(ROS)产生酶Nox1在RAS转化表型的诱导中起重要作用，但目前尚不清楚Nox1是否参与RAS诱导的血管内皮生长因子(VEGF)的上调，血管内皮生长因子是肿瘤血管生成的有力刺激因子。在此，我们描述了在K-RAS转化的正常大鼠肾(KNRK)细胞中，用Nox1小干扰RNAs(SiRNAs)或二苯基碘(DPI)阻断Nox1活性，抑制了VEGF蛋白和VEGFmRNAs的合成。Nox1siRNAs和DPI抑制依赖于细胞外信号调节激酶(ERK)的转录因子Sp1和Sp1与VEGF启动子结合的磷酸化。此外，来自转Nox1siRNA的KNRK细胞的肿瘤显著减少了新生血管。与KNRK细胞一样，Nox1活性是人结肠癌Caco-2细胞产生血管内皮生长因子所必需的。然而，由于Nox1在正常大鼠肾细胞中的过度表达不能诱导血管内皮生长因子的表达，因此仅有Nox1的活性不足以上调血管内皮生长因子的表达，这表明与先前提出的模型不同，Nox1可能与整合到RAS网络中的其他效应物协同作用。我们认为，Nox1通过依赖Ras-ERK的Sp1磷酸化来激活Sp1，从而介导RAS诱导的VEGF表达上调和血管生成。
Reactive oxygen species (ROS)-generating enzyme Nox1 is important in the induction of oncogenic Ras transformation phenotypes, but it is not defined whether Nox1 is involved in Ras-induced upregulation of vascular endothelial growth factor (VEGF), a potent stimulator of tumor angiogenesis. Here we describe that ablation of the Nox1 activity by Nox1 small-interference RNAs (siRNAs) or diphenylene iodonium (DPI) inhibited synthesis of both VEGF proteins and VEGF mRNAs in K-Ras transformed normal rat kidney (KNRK) cells. Nox1siRNAs and DPI suppressed extracellular signal-regulated kinase (ERK)dependent phosphorylation of a transcription factor Sp1 and Sp1 binding to a VEGF promoter. Furthermore, tumors derived from Nox1siRNA-transfected KNRK cells markedly decreased neovascularization. The Nox1 activity was required for VEGF production in human colon cancer CaCO-2 cells, as in the case of KNRK cells. However, since overexpression of Nox1 in normal rat kidney cells failed to induce VEGF, the Nox1 activity alone was not sufficient to upregulate VEGF expression, which suggests that unlike the previously proposed model, Nox1 may act in concert with other effectors integrated into the Ras network. We propose that Nox1 mediates oncogenic Ras-induced upregulation of VEGF and angiogenesis by activating Sp1 through Ras-ERK-dependent phosphorylation of Sp1.