Detection by 32P-postlabelling of 8-oxo-7,8-dihydro-2'-deoxyguanosine in DNA as biomarker of microcystin-LR- and nodularin-induced DNA damage in vitro in primary cultured rat hepatocytes and in vivo in rat liver.
Microcystin-LR (MCYST-LR) and nodularin (NOD) produced by cyanobacteria are potent and specific hepatotoxins. The induction of free-radical formation, reduction of glutathione levels and induction of DNA damage are three major events found in rat hepatocytes treated with these hepatotoxins. However, the mechanism of MCYST-LR- and NOD-mediated induction of oxidative DNA damage has not been fully elucidated. The objective of this study was to determine whether MCYST-LR and NOD increase the formation of a DNA oxidative damage marker such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) in vitro in primary rat hepatocytes and in vivo in rat liver cells. Rat hepatocytes were exposed to MCYST-LR or NOD at low doses (2 and 10 ng/ml), at which there is no evidence of morphologically apparent cytotoxic effects, as well as an induced dose- and time-dependent formation of 8-oxo-dG. Moreover, MCYST-LR treatment of rats (50 microg/kg, ip) resulted in a significant increase of 8-oxo-dG in liver DNA, at 24 h after treatment before decreasing at 48 h. However, NOD-induced DNA damage was increased both at 24 and 48 h, in contrast to the MCYST-LR-induced effect. The effects on this oxidative DNA damage marker indicates that MCYST-LR and NOD do evoke oxidative stress, which may contribute, at least in part, to their liver toxicity and carcinogenicity during long-term exposure.
Maatouk
Imed
I
Laboratoire Raymond Latarjet, Institut Curie-Section Recherche, Bâtiment 112, Centre Universitaire, 91405 Orsay Cedex, France.
Bouaïcha
Noureddine
N
Plessis
Marie José
MJ
Périn
François
F
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D015415:Biomarkers; D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry / Q000187:drug effects*; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000633:toxicity; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic / Q000633:toxicity*; D010761:Phosphorus Radioisotopes / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D015415:Biomarkers; D004791:Enzyme Inhibitors; D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; D010761:Phosphorus Radioisotopes; C063998:nodularin; D000080242:8-Hydroxy-2'-Deoxyguanosine; D004247:DNA; C057862:cyanoginosin LR; D003849:Deoxyguanosine