| Abstract: | Radiation affects several cellular and molecular processes, including double
strand breakage and modifications of sugar moieties and bases. In outer space,
protons are the primary radiation source that poses a range of potential health
risks to astronauts. On the other hand, the use of proton irradiation for tumor
radiation therapy is increasing, as it largely spares healthy tissues while
killing tumor tissues. Although radiation-related research has been conducted
extensively, the molecular toxicology and cellular mechanisms affected by proton
irradiation remain poorly understood. Therefore, in this study, we irradiated
rat lung epithelial cells with different doses of protons and investigated their
effects on cell proliferation and death. Our data show an inhibition of cell
proliferation in proton-irradiated cells with a significant dose-dependent
activation and repression of reactive oxygen species and antioxidants
glutathione and superoxide dismutase, respectively, compared with control cells.
In addition, the activities of apoptosis-related genes such as caspase-3 and -8
were induced in a dose-dependent manner with corresponding increased levels of
DNA fragmentation in proton-irradiated cells compared with control cells.
Together, our results show that proton irradiation alters oxidant and
antioxidant levels in cells to activate the apoptotic pathway for cell
death. |
