title: In vitro gene expression data supporting a DNA non-reactive genotoxic mechanism for ochratoxin A.
abstract: Ochratoxin A (OTA) is a mycotoxin often found in cereals and agricultural products. There is unequivocal evidence of renal carcinogenicity of OTA in male rats, although the mechanism of action is unknown. At present, available data support an epigenetic mechanism (DNA non-reactive) resulting from oxidative stress and cytotoxicity, because a direct OTA interaction with DNA has not been demonstrated. Genotoxic mechanism (DNA-reactive vs. DNA non-reactive) may have implications on human risk assessment. Therefore, the aim of the present work was to identify biological pathways modulated by OTA in vitro in a human renal cell line (HK-2) to contribute to the elucidation of the mechanism of OTA toxicity. For that purpose, cells were exposed to 50 microM OTA during 6 and 24 h, and gene expression profiles were analyzed using Affymetrix Human Genome U133 A 2.0 Gene Chips. Under the same experimental conditions, genotoxicity was evaluated by the modified comet assay using FPG and Endo III to detect oxidative DNA damage, and intracellular ROS level by the H(2)DCF assay. After 6 h, with slight cytotoxicity (83% survival), genes involved in mitochondrial electron transport chain were up-regulated; and after 24 h, with a more pronounced cytotoxicity (51% survival), genes implicated in oxidative stress response were also up-regulated. Increase in intracellular ROS level and oxidative DNA damage was evident at both exposure times being more pronounced with high cytotoxicity. On the contrary, up-regulation of genes implicated in DNA damage response, as cell cycle control or apoptosis, was not detected at any exposure time. In conclusion, these results support a DNA non-reactive mechanism of OTA genotoxicity.
authors.affiliation: Department of Food Sciences and Toxicology, Faculty of Pharmacy, University of Navarra, C/Irunlarrea 1, 31008 Pamplona, Spain.
authors.forename: Leire
authors.initials: L
authors.lastname: Arbillaga
authors.forename: Amaia
authors.initials: A
authors.lastname: Azqueta
authors.forename: Joost H M
authors.initials: JH
authors.lastname: van Delft
authors.forename: Adela
authors.initials: A
authors.lastname: López de Cerain
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D020552:Comet Assay; D004247:DNA / Q000187:drug effects / Q000235:genetics*; D004249:DNA Damage; D004579:Electron Transport / Q000187:drug effects; D005456:Fluorescent Dyes; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009153:Mutagens; D009793:Ochratoxins / Q000633:toxicity*; D020411:Oligonucleotide Array Sequence Analysis; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D005456:Fluorescent Dyes; D009153:Mutagens; D009793:Ochratoxins; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; C025589:ochratoxin A; D012313:RNA; D004247:DNA; D007770:L-Lactate Dehydrogenase; C022616:thiazolyl blue