title: Biphasic effects of nitric oxide radicals on radiation-induced lethality and chromosome aberrations in human lung cancer cells carrying different p53 gene status.
abstract: OBJECTIVE
  The aim of this study was to clarify the effects of nitric oxide (NO) on radiation-induced cell killing and chromosome aberrations in two human lung cancer cell lines with a different p53 gene status.
  
  
  METHODS
  We used wild-type (wt) p53 and mutated (m) p53 cell lines that were derived from the human lung cancer H1299 cell line, which is p53 null. The wtp53 and mp53 cell lines were generated by transfection of the appropriate p53 constructs into the parental cells. Cells were pretreated with different concentrations of isosorbide dinitrate (ISDN) (an NO donor) and/or 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) (an NO scavenger) and then exposed to X-rays. Cell survival, apoptosis, and chromosome aberrations were scored by use of a colony-forming assay, Hoechst 33342 staining assay and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP [deoxyuridine triphosphate] nick end labeling) assay, and chromosomal banding techniques, respectively.
  
  
  RESULTS
  In wtp53 cells the induction of radioresistance and the inhibition of apoptosis and chromosome aberrations were observed in the presence of ISDN at low 2- to 10-mumol/L concentrations before X-irradiation. The addition of c-PTIO and ISDN into the culture medium 6 h before irradiation almost completely suppressed these effects. However, at high concentrations of ISDN (100-500 mumol/L), clear evidence of radiosensitization, enhancement of apoptosis, and chromosome aberrations was detected. However, these phenomena were not observed in mp53 cells at either concentration range with ISDN.
  
  
  CONCLUSIONS
  These results indicate that low and high concentrations of NO radicals can choreograph inverse radiosensitivity, apoptosis, and chromosome aberrations in human lung cancer cells and that NO radicals can affect the fate of wtp53 cells.
authors.affiliation: Department of Radiation Medicine, Fourth Military Medical University, Xi'an, China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Su
authors.forename: Akihisa
authors.initials: A
authors.lastname: Takahashi
authors.forename: Guozhen
authors.initials: G
authors.lastname: Guo
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Mori
authors.forename: Noritomo
authors.initials: N
authors.lastname: Okamoto
authors.forename: Ken
authors.initials: K
authors.lastname: Ohnishi
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Takeo
authors.initials: T
authors.lastname: Ohnishi
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects; D001565:Benzoates / Q000008:administration & dosage / Q000494:pharmacology; D045744:Cell Line, Tumor / Q000187:drug effects; D002470:Cell Survival; D002869:Chromosome Aberrations / Q000187:drug effects*; D002871:Chromosome Banding / Q000379:methods; D016158:Genes, p53 / Q000235:genetics*; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D007548:Isosorbide Dinitrate / Q000008:administration & dosage / Q000494:pharmacology; D008175:Lung Neoplasms / Q000235:genetics / Q000532:radiotherapy*; D009569:Nitric Oxide / Q000502:physiology; D020030:Nitric Oxide Donors / Q000008:administration & dosage / Q000494:pharmacology*; D011836:Radiation Tolerance / Q000187:drug effects* / Q000235:genetics; D014410:Tumor Stem Cell Assay / Q000379:methods
chemical_list: D001565:Benzoates; D007093:Imidazoles; D020030:Nitric Oxide Donors; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; D009569:Nitric Oxide; D007548:Isosorbide Dinitrate