Late ROS accumulation and radiosensitivity in SOD1-overexpressing human glioma cells.
This study investigates the hypothesis that CuZn superoxide dismutase (SOD1) overexpression confers radioresistance to human glioma cells by regulating the late accumulation of reactive oxygen species (ROS) and the G(2)/M-checkpoint pathway. U118-9 human glioma cells (wild type, neo vector control, and stably overexpressing SOD1) were irradiated (0-10 Gy) and assayed for cell survival, cellular ROS levels, cell-cycle-phase distributions, and cyclin B1 expression. SOD1-overexpressing cells were radioresistant compared to wild-type (wt) and neo vector control (neo) cells. Irradiated wt and neo cells showed a significant increase (approximately twofold) in DHE fluorescence beginning at 2 days postirradiation, which remained elevated at 8 days postirradiation. Interestingly, the late accumulation of ROS was suppressed in irradiated SOD1-overexpressing cells. The increase in ROS levels was followed by a decrease in cell growth and viability and an increase in the percentage of cells with sub-G(1) DNA content. SOD1 overexpression enhanced radiation-induced G(2) accumulation within 24 h postirradiation, which was accompanied by a decrease in cyclin B1 mRNA and protein levels. These results support the hypothesis that long after radiation exposure a "metabolic redox response" regulates radiosensitivity of human glioma cells.
Gao
Zhen
Z
Free Radical and Radiation Biology Program, Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242, USA.
Sarsour
Ehab H
EH
Kalen
Amanda L
AL
Li
Ling
L
Kumar
Maneesh G
MG
Goswami
Prabhat C
PC
D015153:Blotting, Western; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D056744:Cyclin B1; D004591:Electrophoresis, Polyacrylamide Gel; D005434:Flow Cytometry; D016195:G2 Phase / Q000528:radiation effects; D005910:Glioma / Q000378:metabolism / Q000532:radiotherapy*; D006801:Humans; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000378:metabolism; D011836:Radiation Tolerance; D017382:Reactive Oxygen Species / Q000378:metabolism* / Q000528:radiation effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000378:metabolism*; D000072105:Superoxide Dismutase-1
C534699:CCNB1 protein, human; D019926:Cyclin B; D056744:Cyclin B1; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C000606290:SOD1 protein, human; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1
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