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Reduction in antioxidant defenses may contribute to ochratoxin A toxicity and carcinogenicity

Christophe Cavin1, Thierry Delatour, Maricel Marin-Kuan

  • 1Quality and Safety Department, Nestlé Research Center, CH-1000 Lausanne 26, Switzerland. christophe.cavin@rdls.nestle.com

Toxicological Sciences : an Official Journal of the Society of Toxicology
|November 18, 2006
PubMed

Insights

Ochratoxin A (OTA) inhibits the protective Nrf2 pathway, leading to oxidative DNA damage. This mechanism may explain OTA's kidney toxicity and carcinogenicity in rodents.

Area of Science:

  • Toxicology
  • Molecular Biology
  • Carcinogenesis

Background:

  • Ochratoxin A (OTA) is a known renal carcinogen in rodents, but its human health impact is uncertain.
  • Previous studies indicated reduced Nrf2-dependent gene expression in rat kidneys exposed to OTA.
  • Nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) is crucial for regulating detoxification and antioxidant responses.

Purpose of the Study:

  • To investigate the biological significance of OTA-induced changes in Nrf2-dependent gene expression in the kidney.
  • To elucidate the mechanism underlying OTA nephrotoxicity and carcinogenicity.
  • To assess the role of Nrf2 inhibition in OTA-mediated cellular damage.

Main Methods:

  • Analysis of Nrf2-regulated protein markers in rat kidneys in vivo.
  • Reproduction of OTA effects in NRK renal cells and primary hepatocytes.
  • In vitro assays (electrophoretic mobility shift, luciferase reporter assays) to assess Nrf2 activity.
  • Evaluation of oxidative DNA damage (abasic sites).

Main Results:

  • OTA decreased Nrf2-regulated protein expression in rat kidneys.
  • OTA inhibited Nrf2 activity in vitro, confirmed by reporter assays.
  • Reduced Nrf2 activity led to oxidative DNA damage in vitro and in vivo.
  • Nrf2 inducer pretreatment prevented OTA-mediated effects.

Conclusions:

  • OTA inhibits cellular defense mechanisms against oxidative stress by suppressing Nrf2 activity.
  • Nrf2 inhibition is a plausible mechanism for OTA nephrotoxicity and carcinogenicity.
  • Understanding this pathway is critical for assessing human health risks associated with OTA exposure.

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