1. Combined effects of okadaic acid and cadmium on lipid peroxidation and DNA bases modifications (m5dC and 8-(OH)-dG) in Caco-2 cells.
- Author
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Traoré A, Ruiz S, Baudrimont I, Sanni A, Dano SD, Guarigues P, Narbonne JF, and Creppy EE
- Subjects
- 5-Methylcytosine analogs & derivatives, 8-Hydroxy-2'-Deoxyguanosine, Caco-2 Cells drug effects, Caco-2 Cells metabolism, Chromatography, High Pressure Liquid, Cytosine analogs & derivatives, Cytosine metabolism, DNA metabolism, Deoxyguanosine analogs & derivatives, Deoxyguanosine metabolism, Drug Synergism, Humans, Leucine metabolism, Malondialdehyde metabolism, Protein Synthesis Inhibitors toxicity, Cadmium toxicity, Carcinogens toxicity, DNA drug effects, Enzyme Inhibitors toxicity, Lipid Peroxidation drug effects, Okadaic Acid toxicity
- Abstract
Okadaic acid (OA) is a marine toxin, a tumour promoter and an inducer of apoptosis. It mainly inhibits protein-phosphatases, protein synthesis and enhances lipid peroxidation. Cadmium (Cd) is known to be carcinogenic in animals and humans (group 1 according to the International Agency for Research on Cancer (IARC) classification). Cd also induces oxidative stress in living organisms. Since they are sometimes found simultaneously in mussels, we have evaluated in the present investigation, the lipid peroxidation, as malondialdehyde (MDA) production, in the variation of the ratios of 8-(OH)-dG/10(5)dG and m5dC/(dC + m5dC) induced by OA and/or Cd in Caco-2 cells. When cells were treated exclusively by OA (15 ng/ml) or Cd (0.625 and 5 microg/ml) for 24 h, protein synthesis was inhibited (by 42 +/- 5%, 18 +/- 13%, and 90 +/- 4% respectively) while MDA production was 2,235 +/- 129, 1710 +/- 20, and 11,496 +/-1,624 pmol/mg protein respectively. In addition, each toxicant induced modified bases in DNA; increases in oxidised bases and methylated dC. The combination of OA and cadmium was more cytotoxic and caused more DNA base modifications; the ratio m(5)dC/(m(5)dC + dC) was increased from 3 +/- 0.15 to 9 +/- 0.15 and the ratio 8-(OH)-dG/10(5) dG also (from 36 +/- 2 to 76 +/- 6). The combination of OA and Cd also increased the level of MDA (1,6874 +/- 2,189 pmole/mg protein). The present results strongly suggest that DNA damage resulting from the oxidative stress induced by these two toxicants may significantly contribute to increasing their carcinogenicity via epigenetic processes.
- Published
- 2000
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