Ochratoxin A: induction of (oxidative) DNA damage, cytotoxicity and apoptosis in mammalian cell lines and primary cells.
Ochratoxin A (OTA) is a nephrotoxic/-carcinogenic mycotoxin, produced by several Aspergillus- and Penicillium-strains. Humans are exposed to OTA via food contamination, a causal relationship of OTA to human endemic Balkan nephropathy is still under debate. Since DNA-adducts of OTA or its metabolites could not be identified unambiguously, its carcinogenic effectiveness might be related to secondary effects, such as oxidative cell damage or cell proliferation. In this study, OTA mediated induction of (oxidative) DNA damage, cytotoxicity (necrosis, growth inhibition, apoptosis) and modulation of glutathione were investigated in cell lines (V79, CV-1) and primary rat kidney cells. After 24 h incubation, viability of V79 cells was strongly decreased by OTA concentrations >2.5 micromol/L, whereas CV-1 cells were clearly less sensitive. Strong growth inhibition occurred in both cell lines (IC(50) approximately 2 micromol/L). Apoptosis, detected with an immunochemical test and with flow cytometry, was induced by >1 micromol/L OTA. Oxidative DNA damage, detected by comet assay after additional treatment with repair enzymes, was induced in all cell systems already at five-fold lower concentrations. Glutathione in CV-1 cells was depleted after 1 h incubation (>100 micromol/L). In contrast, an increase was measured after 24 h incubation (>0.5 micromol/L). In conclusion, OTA induces oxidative DNA damage at low, not yet cytotoxic concentrations. Oxidative DNA damage might initiate cell transformation eventually in connection with proliferative response following cytotoxic cell death. Both events might represent pivotal factors in the chain of cellular events leading into nephro-carcinogenicity of OTA.
Kamp
Hennicke G
HG
Department of Chemistry, Division of Food Chemistry and Environmental Toxicology, University of Kaiserslautern, Erwin Schroedinger Strasse 52, D-67663 Kaiserslautern, Germany.
Eisenbrand
Gerhard
G
Schlatter
Josef
J
Würth
Kirsten
K
Janzowski
Christine
C
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002273:Carcinogens / Q000633:toxicity; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002522:Chlorocebus aethiops; D020552:Comet Assay; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000187:drug effects*; D004249:DNA Damage; D043382:DNA-Formamidopyrimidine Glycosylase / Q000494:pharmacology; D004720:Endonucleases / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000187:drug effects; D008297:Male; D009793:Ochratoxins / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar
D002273:Carcinogens; D009793:Ochratoxins; C025589:ochratoxin A; D004247:DNA; D004720:Endonucleases; D043382:DNA-Formamidopyrimidine Glycosylase; D005978:Glutathione