title: Pre-exposure to 50 Hz magnetic fields modifies menadione-induced genotoxic effects in human SH-SY5Y neuroblastoma cells.
abstract: BACKGROUND
  Extremely low frequency (ELF) magnetic fields (MF) are generated by power lines and various electric appliances. They have been classified as possibly carcinogenic by the International Agency for Research on Cancer, but a mechanistic explanation for carcinogenic effects is lacking. A previous study in our laboratory showed that pre-exposure to ELF MF altered cancer-relevant cellular responses (cell cycle arrest, apoptosis) to menadione-induced DNA damage, but it did not include endpoints measuring actual genetic damage. In the present study, we examined whether pre-exposure to ELF MF affects chemically induced DNA damage level, DNA repair rate, or micronucleus frequency in human SH-SY5Y neuroblastoma cells.
  
  
  RESULTS
  Exposure to 50 Hz MF was conducted at 100 µT for 24 hours, followed by chemical exposure for 3 hours. The chemicals used for inducing DNA damage and subsequent micronucleus formation were menadione and methyl methanesulphonate (MMS). Pre-treatment with MF enhanced menadione-induced DNA damage, DNA repair rate, and micronucleus formation in human SH-SY5Y neuroblastoma cells. Although the results with MMS indicated similar effects, the differences were not statistically significant. No effects were observed after MF exposure alone.
  
  
  CONCLUSIONS
  The results confirm our previous findings showing that pre-exposure to MFs as low as 100 µT alters cellular responses to menadione, and show that increased genotoxicity results from such interaction. The present findings also indicate that complementary data at several chronological points may be critical for understanding the MF effects on DNA damage, repair, and post-repair integrity of the genome.
authors: Department of Environmental Science, University of Eastern Finland, Kuopio, Finland. Jukka.Luukkonen@uef.fi
authors: Jukka
authors: J
authors: Luukkonen
authors: Anu
authors: A
authors: Liimatainen
authors: Anne
authors: A
authors: Höytö
authors: Jukka
authors: J
authors: Juutilainen
authors: Jonne
authors: J
authors: Naarala
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects; D006801:Humans; D008280:Magnetics; D008741:Methyl Methanesulfonate / Q000633:toxicity; D015162:Micronucleus Tests; D009153:Mutagens / Q000633:toxicity*; D009447:Neuroblastoma / Q000473:pathology*; D024483:Vitamin K 3 / Q000633:toxicity*
chemical_list: D009153:Mutagens; D024483:Vitamin K 3; D008741:Methyl Methanesulfonate