Induction of cell death through alteration of oxidants and antioxidants in lung epithelial cells exposed to high energy protons.
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.
Department of Biology, Molecular Toxicology Laboratory, Center for Biotechnology and Biomedical Sciences, Norfolk State University, Norfolk, Virginia 23504, USA.
Sudhakar
S
Baluchamy
Prabakaran
P
Ravichandran
Adaikkappan
A
Periyakaruppan
Vani
V
Ramesh
Joseph C
JC
Hall
Ye
Y
Zhang
Olufisayo
O
Jejelowo
Daila S
DS
Gridley
Honglu
H
Wu
Govindarajan T
GT
Ramesh
D000818:Animals; D000975:Antioxidants / Q000737:chemistry*; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D016923:Cell Death; D002470:Cell Survival; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000166:cytology*; D005978:Glutathione / Q000737:chemistry; D008168:Lung / Q000166:cytology*; D016877:Oxidants / Q000737:chemistry*; D011522:Protons; D051381:Rats; D017382:Reactive Oxygen Species
D000975:Antioxidants; D016877:Oxidants; D011522:Protons; D017382:Reactive Oxygen Species; D053148:Caspase 3; D053181:Caspase 8; D005978:Glutathione