Free radical generation in chronic infection and its implication in carcinogenesis

慢性感染中自由基的产生及其在致癌作用中的意义

• 批准号: 11138244
• 负责人: MAEDA Hiroshi
• 金额: $ 4.8万
• 依托单位: Kumamoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas (A)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11138244/
• 关键词: free radical; nitric oxide; peroxynitrite; genomic mutation; viral pathogenesis; carcinogenesis; nitroguanosine

Excessive production of free radicals such as superoxide (O_2^<・->) and nitric oxide (NO) as well as their reaction product, peroxynitrite (ONOO^-) are known to occur during infection and inflammation. These reactive species cause oxidation and nitration of vital molecules including DNA, and hence may involve in mutagenesis and carcinogenesis. In the present study, we investigated the reaction between ONOO- and nucleic acid, particularly the products of damaged nucleic acids. We further studied the impact of ONOO^- on genomic mutation by using Sendai virus (SeV) constracted green fluorescent protein (GFP) as a marker of mutation. High performance liquid chromatography analysis showed that ONOO^- clearly nitrates guanine residues in nucleoside, RNA and DNA.Efficacy of guanine nitration in RNA was as high as that in nucleoside, and 10 times higher than that in DNA.Interestingly, nitroguanosine thus formed was found to produce O_2^<・-> to a significant extent, comparably higher than that by mitomycin C, catalyzed by cytochrome reductase system. These findings suggest that nitration of guanosine by ONOO^- further enhance cellular oxidative stress due to its potential to produce O_2^<・->. Exposure of GFP/SeV to physiologically releavant concentration of ONOO^- (0.8 μM) markedly facilitated the mutation rate of GFP/SeV compared to control GFP/SeV without ONOO^- exposure. Furthermore, in vivo mutation rate of GFP/SeV was also found to depend on NO production during infection as revealed by using NO synthase knock-out mice model. All these findings suggest that reactive nitrogen species may play an important role in infection-associated carcinogensis due to, at least in part, its genotoxic potentials.

已知在感染和炎症过程中会产生过多的自由基，例如超氧化物 (O_2^<·->) 和一氧化氮 (NO) 及其反应产物过氧亚硝酸盐 (ONOO^-)。这些活性物质会导致氧化和炎症。包括DNA在内的重要分子的硝化，因此可能涉及诱变和致癌作用。在本研究中，我们进一步研究了ONOO-与核酸之间的反应，特别是受损核酸的产物。利用仙台病毒（SeV）构建的绿色荧光蛋白（GFP）作为突变标记，研究了ONOO^-对基因组突变的影响。高效液相色谱分析表明，ONOO^-在核苷、RNA和DNA中具有清晰的鸟嘌呤残基。 .RNA中鸟嘌呤硝化的功效与核苷中一样高，比DNA中高10倍。有趣的是，由此形成的硝基鸟苷被发现在细胞色素还原酶系统的催化下显着程度地产生O_2^<·->，相对高于丝裂霉素C。这些发现表明ONOO^-对鸟苷的硝化进一步增强了细胞氧化应激。其产生 O_2^<·-> 的潜力 将 GFP/SeV 暴露于生理相关浓度的 ONOO^- (0.8)。与没有暴露于 ONOO^- 的对照 GFP/SeV 相比，GFP/SeV 的突变率显着提高。此外，通过使用 NO 合酶敲除揭示，GFP/SeV 的体内突变率也依赖于感染期间的 NO 产生。所有这些发现表明，活性氮可能在感染相关的致癌作用中发挥重要作用，至少部分是由于其潜在的遗传毒性。

项目成果

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