PMID- 28565963 OWN - NLM STAT- MEDLINE DCOM- 20171010 LR - 20220716 IS - 1362-3095 (Electronic) IS - 0955-3002 (Print) IS - 0955-3002 (Linking) VI - 93 IP - 10 DP - 2017 Oct TI - Genomic instability induced in distant progeny of bystander cells depends on the connexins expressed in the irradiated cells. PG - 1182-1194 LID - 10.1080/09553002.2017.1334980 [doi] AB - PURPOSE: To examine the time window during which intercellular signaling though gap junctions mediates non-targeted (bystander) effects induced by moderate doses of ionizing radiation; and to investigate the impact of gap junction communication on genomic instability in distant progeny of bystander cells. MATERIALS AND METHODS: A layered cell culture system was developed to investigate the propagation of harmful effects from irradiated normal or tumor cells that express specific connexins to contiguous bystander normal human fibroblasts. Irradiated cells were exposed to moderate mean absorbed doses from 3.7 MeV alpha particle, 1000 MeV/u iron ions, 600 MeV/u silicon ions, or (137)Cs gamma rays. Following 5 h of co-culture, pure populations of bystander cells, unexposed to secondary radiation, were isolated and DNA damage and oxidative stress was assessed in them and in their distant progeny (20-25 population doublings). RESULTS: Increased frequency of micronucleus formation and enhanced oxidative changes were observed in bystander cells co-cultured with confluent cells exposed to either sparsely ionizing ((137)Cs gamma rays) or densely ionizing (alpha particles, energetic iron or silicon ions) radiations. The irradiated cells propagated signals leading to biological changes in bystander cells within 1 h of irradiation, and the effect required cellular coupling by gap junctions. Notably, the distant progeny of isolated bystander cells also exhibited increased levels of spontaneous micronuclei. This effect was dependent on the type of junctional channels that coupled the irradiated donor cells with the bystander cells. Previous work showed that gap junctions composed of connexin26 (Cx26) or connexin43 (Cx43) mediate toxic bystander effects within 5 h of co-culture, whereas gap junctions composed of connexin32 (Cx32) mediate protective effects. In contrast, the long-term progeny of bystander cells expressing Cx26 or Cx43 did not display elevated DNA damage, whereas those coupled by Cx32 had enhanced DNA damage. CONCLUSIONS: In response to moderate doses from either sparsely or densely ionizing radiations, toxic and protective effects are rapidly communicated to bystander cells through gap junctions. We infer that bystander cells damaged by the initial co-culture (expressing Cx26 or Cx43) die or undergo proliferative arrest, but that the bystander cells that were initially protected (expressing Cx32) express DNA damage upon sequential passaging. Together, the results inform the roles that intercellular communication play under stress conditions, and aid assessment of the health risks of exposure to ionizing radiation. Identification of the communicated molecules may enhance the efficacy of radiotherapy and help attenuate its debilitating side-effects. FAU - de Toledo, Sonia M AU - de Toledo SM AD - a Department of Radiology , RUTGERS New Jersey Medical School Cancer Center , Newark , NJ , USA. FAU - Buonanno, Manuela AU - Buonanno M AD - a Department of Radiology , RUTGERS New Jersey Medical School Cancer Center , Newark , NJ , USA. FAU - Harris, Andrew L AU - Harris AL AD - b Pharmacology and Physiology and Neuroscience , RUTGERS New Jersey Medical School Cancer Center , Newark , NJ , USA. FAU - Azzam, Edouard I AU - Azzam EI AD - a Department of Radiology , RUTGERS New Jersey Medical School Cancer Center , Newark , NJ , USA. AD - b Pharmacology and Physiology and Neuroscience , RUTGERS New Jersey Medical School Cancer Center , Newark , NJ , USA. LA - eng GR - P01 CA049062/CA/NCI NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural PT - Research Support, U.S. Gov't, Non-P.H.S. DEP - 20170615 PL - England TA - Int J Radiat Biol JT - International journal of radiation biology JID - 8809243 RN - 0 (Connexins) SB - IM MH - Alpha Particles/adverse effects MH - Bystander Effect/*radiation effects MH - Connexins/*metabolism MH - DNA Damage MH - Dose-Response Relationship, Radiation MH - Fibroblasts/cytology/radiation effects MH - Gap Junctions/metabolism/radiation effects MH - Gene Expression Regulation/*radiation effects MH - Genomic Instability/*radiation effects MH - Humans MH - Intracellular Space/metabolism/radiation effects MH - Oxidation-Reduction/radiation effects MH - Permeability/radiation effects PMC - PMC9233304 MID - NIHMS1501382 OTO - NOTNLM OT - Bystander effects OT - channel permeability OT - gap junctions OT - genomic instability OT - non-targeted effects OT - radiation quality COIS- DISCLOSURES The authors declare that they have no competing or conflicting interests. EDAT- 2017/06/02 06:00 MHDA- 2017/10/11 06:00 PMCR- 2022/06/25 CRDT- 2017/06/02 06:00 PHST- 2017/06/02 06:00 [pubmed] PHST- 2017/10/11 06:00 [medline] PHST- 2017/06/02 06:00 [entrez] PHST- 2022/06/25 00:00 [pmc-release] AID - 10.1080/09553002.2017.1334980 [doi] PST - ppublish SO - Int J Radiat Biol. 2017 Oct;93(10):1182-1194. doi: 10.1080/09553002.2017.1334980. Epub 2017 Jun 15.