期刊
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
卷 58, 期 3, 页码 851-861出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.ijrobp.2003.10.022
关键词
MnSOD; ascorbate; reactive oxygen species; spin trap
资金
- NCI NIH HHS [1-R01-CA83876] Funding Source: Medline
- NINDS NIH HHS [F05, NS043922] Funding Source: Medline
Purpose: To determine whether increased expression of manganese superoxide dismutase (MnSOD) protects cells from irradiation by preventing the production of reactive oxygen species (ROS), a new approach to detecting free radical intermediates using ascorbate as an endogenous spin trap was used. Materials and Methods: Cells from the 32D cl 3 hematopoietic cell line or a subclone overexpressing MnSOD (2C6) were incubated with dehydroascorbate for 30 min and irradiated to doses from 0 to 50 Gy. Radical intermediates reacting with spin traps or ascorbate were measured by electron spin resonance spectroscopy. Results were compared to irradiation-induced changes in thiol levels, irradiation survival curves, and accumulation of 8-OHdG as a measurement of DNA oxidative damage. Results: Manganese superoxide dismutase-overexpressing 2C6 cells maintained higher levels of ascorbate (5.4 +/- 0.5 and 2.6 +/- 0.5 nmol/10(6) cells, respectively) and thiols (14.0 +/- 0.1 and 11.1 +/- 0.2 nmol/10(6) cells) compared to 32D cl 3 parent cells. Cells overexpressing MnSOD produced lower levels of ROS than did the parental 32D cl 3 cells, as evidenced by lower expenditure of ascorbate and GSH after irradiation. Increased ascorbate levels protected both 32D cl 3 and 2C6 cells from irradiation killing, as demonstrated by an increased shoulder on survival curves and decreased DNA 8-OHdG accumulation. Conclusions: Manganese superoxide dismutase overexpression protects 2C6 cells from irradiation damage by scavenging ROS that readily interact with major endogenous antioxidants-ascorbate and GSH-in nontransfected hematopoietic 32D cl 3 cells. (C) 2004 Elsevier Inc.
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