Liu R, Buettner G R, Oberley L W
Radiation Research Laboratory, The University of Iowa, Iowa City, IA 52242-1101, USA.
Free Radic Biol Med. 2000 Apr 15;28(8):1197-205. doi: 10.1016/s0891-5849(00)00237-9.
In this study, the hypothesis that oxygen free radicals act as intracellular messengers is examined. Treatment of human oral carcinoma SCC-25 cells with 200 ng/ml human TNF-alpha for 6 h greatly increased manganese superoxide dismutase (MnSOD) gene expression as detected by western blotting, RT-PCR, and nuclear run-on experiments. In the presence of the oxygen free radical spin trapping reagent, 5,5-dimethyl pyrroline-N-oxide (DMPO), the induction of MnSOD gene expression by TNF-alpha was significantly reduced. Electron paramagnetic resonance experiments showed that the production of oxygen free radicals was enhanced in TNF-alpha treated cells. Taken together, these observations suggest that the induction of MnSOD expression by TNF-alpha is at least partially mediated by intracellular formation of oxygen free radicals, and that superoxide is most likely the initiating species involved in the mediation of MnSOD gene expression by TNF-alpha.
在本研究中，对氧自由基作为细胞内信使的假说进行了检验。用200 ng/ml人肿瘤坏死因子-α（TNF-α）处理人口腔癌SCC-25细胞6小时，通过蛋白质免疫印迹法、逆转录聚合酶链反应（RT-PCR）和细胞核转录实验检测发现，锰超氧化物歧化酶（MnSOD）基因表达显著增加。在氧自由基自旋捕获试剂5,5-二甲基吡咯啉-N-氧化物（DMPO）存在的情况下，TNF-α对MnSOD基因表达的诱导作用显著降低。电子顺磁共振实验表明，经TNF-α处理的细胞中氧自由基的产生增强。综上所述，这些观察结果表明，TNF-α对MnSOD表达的诱导作用至少部分是由细胞内氧自由基的形成介导的，并且超氧化物很可能是参与TNF-α介导MnSOD基因表达的起始物质。
