Radiation-induced double strand breaks and subsequent apoptotic DNA             fragmentation in human peripheral blood mononuclear cells.
In case of accidental radiation exposure or a nuclear incident, physical             dosimetry is not always complete. Therefore, it is important to develop tools             that allow dose estimates and determination that are based on biological markers             of radiation exposure. Exposure to ionizing radiation triggers a large-scale activation             of specific DNA signaling and repair mechanisms. This includes the phosphorylation             of γH2AX in the vicinity of a double-strand break (DSB). A DNA DSB is a cytotoxic             form of DNA damage, and if not correctly repaired can initiate genomic instability,             chromosome aberrations, mutations or apoptosis. Measurements of DNA DSBs and their             subsequent repair after in vitro irradiation has been suggested to be of potential             use to monitor cellular responses. The bone marrow and the blood are known to             be the most radiosensitive tissues of the human body and can therefore be of particular             importance to find radiation-induced biological markers. In the present study,             changes in H2AX phosphorylation and apoptosis of irradiated human peripheral blood             mononuclear cells (PBMCs) were analyzed. Freshly isolated PBMCs from healthy donors             were irradiated with X-rays (0.1, 0.25, 0.5, 1, 2 and 4 Gy). The phosphorylation             of γH2AX was measured at different time points (0, 0.25, 1, 2, 4, 6 and 24 h)             after irradiation. We detected a linear dose-dependency of γH2AX phosphorylation             measured by γH2AX foci scoring using immunofluorescence microscopy as well as             by γH2AX fluorescence detection using flow cytometry. Apoptosis was detected by             measuring DNA fragmentation at different time points (0, 24, 48, 72, 96 h) after             X-irradiation using DNA ladder gel electrophoresis. The apoptotic DNA fragmentation             increased in a dose-dependent manner. In conclusion, DNA DSBs and subsequent apoptotic             DNA fragmentation monitoring have potential as biomarkers for assessing human             exposure in radiation biodosimetry.
Radiobiology Unit, Molecular and Cellular Biology, Belgian Nuclear                     Research Centre, SCK•CEN, B-2400 Mol, Belgium.
Myriam
M
Ghardi
Marjan
M
Moreels
Bernard
B
Chatelain
Christian
C
Chatelain
Sarah
S
Baatout
D017209:Apoptosis / Q000528:radiation effects*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D053938:DNA Fragmentation / Q000528:radiation effects*; D006657:Histones / Q000378:metabolism*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D010766:Phosphorylation / Q000528:radiation effects; D014965:X-Rays
C468783:H2AX protein, human; D006657:Histones; D004247:DNA