title: Effect of gap junctional intercellular communication on radiation responses in neoplastic human cells.
abstract: Gap junctional intercellular communication (GJIC) is an important function of metazoan cells and is believed to have beneficial effects in anti-tumor therapy. In this study, we found that, when neoplastic human salivary gland (HSG) cells were irradiated with a 100 keV/microm carbon-ion beam, micronuclei, G(2)/M-phase arrest, and cell killing were induced and that their induction increased with dose. Treatment of confluent HSG cells with 8-Br-cAMP increased GJIC between cells. After release from this treatment, the cell cycle progress and the formation of binucleated cells were still similar to those of untreated cells. However, radiation-induced cellular damage, including micronucleus (MN) formation and G(2)/M-phase arrest of that cAMP-treated population, was less than that of the untreated population and that the surviving fraction was slightly enhanced by cAMP treatment, suggesting that increased GJIC protects HSG cells from lethal radiation damage. Moreover, when confluent HSG cells were treated with 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO), a scavenger of nitric oxide (NO) free radical, MN induction and cell killing in the irradiated population were increased. Our results indicate that NO may be involved in GJIC-mediated radioprotection of HSG cells, which may have implications for radiotherapy.
authors.affiliation: Institute of Radiation Medicine, Fudan University, Shanghai 200032, China. clshao@shmu.edu.cn
authors.forename: Chunlin
authors.initials: C
authors.lastname: Shao
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Furusawa
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Yan
authors.initials: Y
authors.lastname: Pan
authors.forename: Ping
authors.initials: P
authors.lastname: Xu
authors.forename: Honghong
authors.initials: H
authors.lastname: Chen
mesh_terms: D002450:Cell Communication / Q000187:drug effects / Q000528:radiation effects*; D002453:Cell Cycle / Q000528:radiation effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology; D003497:Cyclic N-Oxides / Q000494:pharmacology; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D012468:Salivary Gland Neoplasms / Q000378:metabolism* / Q000473:pathology* / Q000532:radiotherapy
chemical_list: D003497:Cyclic N-Oxides; D007093:Imidazoles; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; D000242:Cyclic AMP