Protective effects of vitamin A against the genotoxicity of NNK, a nicotine-derived N-nitrosamine

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A General Method for Detecting Nitrosamide Formation in the In Vitro Metabolism of Nitrosamines by Cytochrome P450s
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A General Method for Detecting Nitrosamide Formation in the In Vitro Metabolism of Nitrosamines by Cytochrome P450s

Published on: September 25, 2017

M A Alaoui-Jamali1, G Rossignol, A Castonguay

  • 1Laboratory of Cancer Etiology and Chemoprevention, School of Pharmacy, Laval University, Quebec, Canada.

Carcinogenesis
|March 1, 1991
PubMed

Insights

Vitamin A supplementation reduces genotoxic damage in rat liver caused by NNK (4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone). This is linked to decreased NNK metabolism and fewer DNA strand breaks, highlighting vitamin A

Area of Science:

  • Toxicology
  • Nutritional Biochemistry
  • Carcinogenesis Research

Background:

  • 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent carcinogen that induces genotoxic damage.
  • Vitamin A plays a crucial role in cellular processes and may influence the metabolism and toxicity of xenobiotics.
  • Understanding the interplay between vitamin A status and NNK-induced liver damage is vital for cancer prevention strategies.

Purpose of the Study:

  • To investigate the effect of vitamin A on NNK-induced genotoxicity in rat liver.
  • To correlate vitamin A's effect with alterations in NNK metabolism and DNA single strand breaks (DNA-SSBs).
  • To elucidate the role of cell proliferation in NNK-induced genotoxicity.

Main Methods:

  • Rats were fed vitamin A-deficient or supplemented diets, followed by NNK administration and partial hepatectomy.
  • Micronucleus (MN) formation was assessed as a marker of genotoxicity.
  • NNK metabolism and DNA-SSBs were evaluated in isolated hepatocytes.

Main Results:

  • Vitamin A supplementation significantly decreased NNK-induced micronucleus formation in partially hepatectomized rats compared to vitamin A-deficient rats.
  • Hepatocytes from vitamin A-supplemented rats showed reduced NNK metabolism, specifically inhibiting the activation pathway (alpha-carbon hydroxylation).
  • Vitamin A supplementation led to a reduction in NNK-induced DNA single strand breaks in isolated hepatocytes.

Conclusions:

  • Vitamin A deficiency exacerbates NNK-induced genotoxicity in rat liver, likely by enhancing NNK metabolism and DNA damage.
  • Vitamin A supplementation offers a protective effect against NNK-induced liver damage by modulating NNK metabolism and reducing DNA strand breaks.
  • Cell proliferation is essential for micronucleus formation following NNK exposure.

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