title: Rescue effects in radiobiology: unirradiated bystander cells assist irradiated cells through intercellular signal feedback.
abstract: Mammalian cells respond to ionization radiation by sending out extracellular signals to affect non-irradiated neighboring cells, which is referred to as radiation induced bystander effect. In the present paper, we described a phenomenon entitled the "rescue effects", where the bystander cells rescued the irradiated cells through intercellular signal feedback. The effect was observed in both human primary fibroblast (NHLF) and cancer cells (HeLa) using two-cell co-culture systems. After co-culturing irradiated cells with unirradiated bystander cells for 24h, the numbers of 53BP1 foci, corresponding to the number of DNA double-strand breaks in the irradiated cells were less than those in the irradiated cells that were not co-cultured with the bystander cells (0.78±0.04foci/cell vs. 0.90±0.04foci/cell) at a statistically significant level. Similarly, both micronucleus formation and extent of apoptosis in the irradiated cells were different at statistically significant levels if they were co-cultured with the bystander cells. Furthermore, it was found that unirradiated normal cells would also reduce the micronucleus formation in irradiated cancer cells. These results suggested that the rescue effects could participate in repairing the radiation-induced DNA damages through a media-mediated signaling feedback, thereby mitigating the cytotoxicity and genotoxicity of ionizing radiation.
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong, Hong Kong.
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: W
authors.initials: W
authors.lastname: Han
authors.forename: S K
authors.initials: SK
authors.lastname: Chiu
authors.forename: L
authors.initials: L
authors.lastname: Zhu
authors.forename: L
authors.initials: L
authors.lastname: Wu
authors.forename: K N
authors.initials: KN
authors.lastname: Yu
mesh_terms: D000512:Alpha Particles; D017209:Apoptosis / Q000528:radiation effects; D024201:Bystander Effect / Q000528:radiation effects*; D002450:Cell Communication / Q000528:radiation effects*; D002478:Cells, Cultured; D018920:Coculture Techniques; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects; D025461:Feedback, Physiological / Q000528:radiation effects*; D005347:Fibroblasts / Q000378:metabolism / Q000528:radiation effects; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D048629:Micronuclei, Chromosome-Defective / Q000528:radiation effects; D015162:Micronucleus Tests; D018613:Microscopy, Confocal; D011853:Radiobiology / Q000295:instrumentation / Q000379:methods; D015398:Signal Transduction / Q000528:radiation effects*; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C498301:TP53BP1 protein, human; D000071857:Tumor Suppressor p53-Binding Protein 1