Different involvement of radical species in irradiated and bystander cells.
OBJECTIVE
To examine whether nitric oxide (NO) and other radical species are involved in radiation-induced bystander effects in normal human fibroblasts.


METHODS
Bystander effects were modeled by co-culture of non-irradiated cells with X-irradiated cells, and induction levels of micronuclei in co-cultured non-irradiated cells were examined. Three types of radical scavenger, 2-(4-carboxyphenyl)-4,4,5,5- tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), dimethylsulfoxide (DMSO) and ascorbic acid phosphoric ester magnesium salt (APM), were used to discover which types of radicals are involved in bystander responses.


RESULTS
When irradiated cells were treated with c-PTIO, known to be an NO scavenger, the induction of micronuclei in non-irradiated bystander cells was suppressed. On the other hand, bystander effects were most effectively suppressed when non-irradiated bystander cells were treated with ascorbic acid, known to be a scavenger of long lived radicals.


CONCLUSIONS
These results suggest that NO participates in bystander signal formation in irradiated cells but not in bystander cells that are receiving bystander signals.
Harada
Tadayuki
T
Division of Radiation Biology, Department of Radiology and Radiation Biology, Course of Life Sciences and Radiation Research, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
Kashino
Genro
G
Suzuki
Keiji
K
Matsuda
Naoki
N
Kodama
Seiji
S
Watanabe
Masami
M
D024201:Bystander Effect / Q000187:drug effects / Q000528:radiation effects*; D002460:Cell Line; D018920:Coculture Techniques; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D016166:Free Radical Scavengers / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism*; D006801:Humans; D009569:Nitric Oxide / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
D016166:Free Radical Scavengers; D005609:Free Radicals; D017382:Reactive Oxygen Species; D009569:Nitric Oxide