ROS-generating oxidases Nox1 and Nox4 contribute to oncogenic Ras-induced premature senescence
ROS-generating oxidases Nox1 and Nox4 contribute to oncogenic Ras-induced premature senescence
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DOI：
10.1111/gtc.12015
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发表时间：
2013-01-01
期刊：
影响因子：
2.1
通讯作者：
Kamata, Tohru
中科院分区：
文献类型：
--
作者：
Kodama, Ryo;Kato, Masayoshi;Kamata, Tohru
激活的癌基因导致细胞过早衰老，这是一种在原始啮齿动物和人类成纤维细胞中永久的增殖停滞状态。最近的研究表明，活性氧物种(ROS)的产生参与了RAS诱导的致癌早衰。然而，控制这种氧化剂介导的不可逆生长停滞的信号机制还不完全清楚。在这里，我们发现通过RAS/MEK途径，RAS癌基因上调了大鼠REF52细胞中超氧化物歧化酶、NOX1和原代人肺TIG-3细胞中NOX4的表达，导致细胞内ROS水平的增加。用小干扰RNA(SiRNAs)阻断NOX1和NOX4可以阻断RasV12的衰老表型，包括β-半乳糖苷酶活性、生长停滞和肿瘤抑制因子如p53和p16(Ink4a)的积累。这表明，NOx产生的ROS通过激活p53和p16(INK4A)途径来转导衰老信号。此外，NOX1和NOX4 siRNAs同时抑制RAS诱导的DNA损伤反应和p38MAPK的激活，而过表达NOX1和NOX4单独能够诱导衰老。Nox1基因敲除小鼠的胚胎成纤维细胞也证实了Nox1参与RAS诱导的衰老。综上所述，这些发现表明，NOX1和NOX4产生的ROS在RAS诱导的早衰过程中起着重要作用，这可能涉及DNA损伤反应和p38MAPK信号通路。
Activated oncogenes induce premature cellular senescence, a permanent state of proliferative arrest in primary rodent and human fibroblasts. Recent studies suggest that generation of reactive oxygen species (ROS) is involved in oncogenic Ras-induced premature senescence. However, the signaling mechanism controlling this oxidant-mediated irreversible growth arrest is not fully understood. Here, we show that through the Ras/MEK pathway, Ras oncogene up-regulated the expression of superoxide-generating oxidases, Nox1 in rat REF52 cells and Nox4 in primary human lung TIG-3 cells, leading to an increase in intracellular level of ROS. Ablation of Nox1 and Nox4 by small interfering RNAs (siRNAs) blocked the RasV12 senescent phenotype including beta-galactosidase activity, growth arrest and accumulation of tumor suppressors such as p53 and p16(Ink4a). This suggests that Nox-generated ROS transduce senescence signals by activating the p53 and p16(Ink4a) pathway. Furthermore, Nox1 and Nox4 siRNAs inhibited both Ras-induced DNA damage response and p38MAPK activation, whereas overexpression of Nox1 and Nox4 alone was able to induce senescence. The involvement of Nox1 in Ras-induced senescence was also confirmed with embryonic fibroblasts derived from Nox1 knockout mice. Together, these findings suggest that Nox1- and Nox4-generated ROS play an important role in Ras-induced premature senescence, which may involve DNA damage response and p38MAPK signaling pathways.