Lab of Translational Medicine, Gachon University of Medicine and Science, Lee Gil Ya Cancer and Diabetes Institute, Songdo-dong 7-45, Yeonsu-gu, Incheon, Republic of Korea.
Biochem Pharmacol. 2011 Jan 1;81(1):111-22. doi: 10.1016/j.bcp.2010.08.023. Epub 2010 Sep 9.
Reactive oxygen species (ROS) attack guanine bases in DNA and form 8-hydroxydeoxyguanosine (8-OHdG), which has been regarded simply as an oxidative mutagenic by-product. On the other hand, our previous report showed paradoxically ROS attenuating action of generated 8-OHdG. In the current study, both in vitro and in vivo experiments were executed in order to document anti-oxidative and anti-inflammatory actions of 8-OHdG in cell model and to elucidate the therapeutic efficacy against water immersion restraint stress (WIRS)-induced gastritis animal model. Electron spin resonance measurements showed that 8-OHdG at >5μg/ml completely scavenged OH(-) radicals, which was further confirmed by checking 2'-7'-dichlorodihydrofluorescein diacetate (DCFDA) spectroscopy. On molecular assay, 8-OHdG antagonized the action of GTP on Rac, a small GTP binding protein, without affecting Rac-guanosine exchange factor (GEF) or phosphoinositide 3-kinases (PI3K) activity. In Raw264.7 cells, 8-OHdG was found to be associated with marked attenuations of NOX1, NOXO1, and NOXA1 accompanied with the decreased expressions of LPS-induced inflammatory mediators including COX-2, iNOS, IL-1β, and IL-6. Similarly, 8-OHdG attenuated hypoxia-induced angiogenesis and platelet endothelial cell adhesion molecule-1 (PECAM-1), COX-2, iNOS, IL-8, and VEGF expressions in HUVEC cells. At transcriptional level, 8-OHdG inhibited the nuclear translocation of NF-κB, inhibitory κB kinase (IKK) β kinase activation, and decreased phospho-IκBα levels. 8-OHdG efficiently ameliorated WIRS-induced gastric mucosal injury as evidenced with improvement of gross lesion index and attenuation of engaging mediators. Taken together, exogenous 8-OHdG can be a functional molecule regulating oxidative stress-induced gastritis through either antagonizing Rac-GTP binding or blocking the signals responsible for gastric inflammatory cascade.
活性氧 (ROS) 攻击 DNA 中的鸟嘌呤碱基，并形成 8-羟基脱氧鸟苷 (8-OHdG)，它一直被简单地视为氧化致突变的副产物。另一方面，我们之前的报告显示，ROS 出人意料地具有减弱生成的 8-OHdG 的作用。在本研究中，我们进行了体外和体内实验，以记录 8-OHdG 在细胞模型中的抗氧化和抗炎作用，并阐明其对水浸束缚应激 (WIRS) 诱导的胃炎动物模型的治疗效果。电子自旋共振测量表明，8-OHdG 在 >5μg/ml 时完全清除了 OH(-)自由基，这通过检查 2'-7'-二氯二氢荧光素二乙酸酯 (DCFDA) 光谱得到了进一步证实。在分子测定中，8-OHdG 拮抗了 GTP 对 Rac 的作用，Rac 是一种小 GTP 结合蛋白，而不影响 Rac-鸟苷交换因子 (GEF) 或磷酯酰肌醇 3-激酶 (PI3K) 活性。在 Raw264.7 细胞中，发现 8-OHdG 与 NOX1、NOXO1 和 NOXA1 的表达明显减弱有关，同时伴有 LPS 诱导的炎症介质如 COX-2、iNOS、IL-1β 和 IL-6 的表达减少。同样，8-OHdG 减弱了缺氧诱导的血管生成和血小板内皮细胞粘附分子-1 (PECAM-1)、COX-2、iNOS、IL-8 和 VEGF 在 HUVEC 细胞中的表达。在转录水平上，8-OHdG 抑制了 NF-κB 的核转位、抑制性 κB 激酶 (IKK)β 激酶的激活，并降低了磷酸化 IκBα 的水平。8-OHdG 有效地改善了 WIRS 诱导的胃黏膜损伤，表现为大体病变指数的改善和抑制参与的介质。总之，外源性 8-OHdG 可以通过拮抗 Rac-GTP 结合或阻断负责胃炎症级联反应的信号来调节氧化应激诱导的胃炎。
