title: Low-dose gamma irradiation enhances superoxide anion production by nonirradiated cells through TGF-β1-dependent bystander signaling.
abstract: We show here that low-dose gamma irradiation substantially increase in extracellular superoxide anion production in oncogenically transformed cells and tumor cells but not by nontransformed cells. The transfer of only a few cells from an irradiated culture to nonirradiated control cells was sufficient for the transmission of a signal to induce superoxide anion production in the nonirradiated cells. The number of irradiated cells that was necessary for the successful induction of superoxide anion production in the nonirradiated cells depended on radiation dose. When irradiated cells were allowed to incubate for 1 h before transmission to the nonirradiated cultures, nearly all of the cells from the irradiated cell population were able to communicate the inducing signal to nonirradiated cells. siRNA-dependent knockdown and reconstitution experiments showed that TGF-β1 was sufficient to mediate the bystander effect triggered by low-dose radiation in this experimental system. A kinetic analysis demonstrated that the enhanced superoxide anion production was substantially reduced before the release of the bystander signal by activated TGF-β.
authors: Abteilung Virologie, Institut für Medizinische Mikrobiologie und Hygiene, Universität Freiburg, Germany.
authors: Jennifer
authors: J
authors: Temme
authors: Georg
authors: G
authors: Bauer
mesh_terms: D000818:Animals; D024201:Bystander Effect / Q000528:radiation effects*; D005720:Gamma Rays; D006801:Humans; D006834:Hydrazines / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology; D051381:Rats; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000502:physiology*
chemical_list: D006834:Hydrazines; D053773:Transforming Growth Factor beta1; D013481:Superoxides; D009569:Nitric Oxide; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; D013482:Superoxide Dismutase