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|Section2= |Section3= }} 8-Oxo-2'-deoxyguanosine (8-oxo-dG) is an oxidized derivative of deoxyguanosine. 8-oxo-dG is one of the major products of DNA oxidation. Concentrations of 8-oxo-dG within a cell are a measurement of oxidative stress. ==8-oxo-dG in DNA== Steady-state levels of DNA damages represent the balance between formation and repair. Swenberg et al.〔Swenberg JA, Lu K, Moeller BC, Gao L, Upton PB, Nakamura J, Starr TB. (2011) Endogenous versus exogenous DNA adducts: their role in carcinogenesis, epidemiology, and risk assessment. Toxicol Sci. 120(Suppl 1):S130-45. PMID 21163908〕 measured average frequencies of steady state endogenous DNA damages in mammalian cells. The most frequent oxidative DNA damage normally present in DNA is 8-oxo-dG, occurring at an average frequency of 2,400 per cell. When 8-oxo-dG is induced by a DNA damaging agent it is rapidly repaired. For example, 8-oxo-dG was increased 10-fold in the livers of mice subjected to ionizing radiation, but the excess 8-oxo-dG was rapidly removed with a half-life of 11 minutes. As reviewed by Valavanidis et al. increased levels of 8-oxo-dG in a tissue can serve as a biomarker of oxidative stress. They also noted that increased levels of 8-oxo-dG are frequently found during carcinogenesis. In the figure shown in this section, the colonic epithelium from a mouse on a normal diet has a low level of 8-oxo-dG in its colonic crypts (panel A). However, a mouse likely undergoing colonic tumorigenesis (due to deoxycholate added to its diet〔) has a high level of 8-oxo-dG in its colonic epithelium (panel B). Deoxycholate increases intracellular production of reactive oxygen resulting in increased oxidative stress,〔Tsuei J, Chau T, Mills D, Wan YJ. Bile acid dysregulation, gut dysbiosis, and gastrointestinal cancer. Exp Biol Med (Maywood). 2014 Nov;239(11):1489-504. doi: 10.1177/1535370214538743. PMID 24951470〕〔Ajouz H, Mukherji D, Shamseddine A. Secondary bile acids: an underrecognized cause of colon cancer. World J Surg Oncol. 2014 May 24;12:164. doi: 10.1186/1477-7819-12-164. Review. PMID 24884764〕 and this leads to tumorigenesis and carcinogenesis. Of 22 mice fed the diet supplemented with deoxycholate, 20 (91%) developed colonic tumors after 10 months on the diet, and the tumors in 10 of these mice (45% of mice) included an adenocarcinoma (cancer).〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「8-Oxo-2'-deoxyguanosine」の詳細全文を読む スポンサード リンク
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