Posted: 20 Dec 2004 05:10
Subject: Ochratoxin A: induction of (oxidative) DNA damage, cytotoxic

Volume 206, Issue 3 , 31 January 2005, Pages 413-425

Copyright © 2004 Elsevier Ireland Ltd All rights reserved.
Ochratoxin A: induction of (oxidative) DNA damage, cytotoxicity and apoptosis in mammalian cell lines and primary cells

Hennicke G. Kampa, Gerhard Eisenbranda, Josef Schlatterb, Kirsten Würtha and Christine Janzowskia, ,

aDepartment of Chemistry, Division of Food Chemistry and Environmental Toxicology, University of Kaiserslautern, Erwin Schroedinger Straße 52, D-67663 Kaiserslautern, Germany
bSwiss Federal Office of Public Health, Food Toxicology Section, Stauffacherstrasse 101, CH-8004 Zürich, Switzerland

Received 24 May 2004; revised 2 August 2004; accepted 2 August 2004. Available online 15 September 2004.

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 μmol/L, whereas CV-1 cells were clearly less sensitive. Strong growth inhibition occurred in both cell lines (IC50 2 μmol/L). Apoptosis, detected with an immunochemical test and with flow cytometry, was induced by >1 μmol/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 μmol/L). In contrast, an increase was measured after 24 h incubation (>0.5 μmol/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.