Toxicity and DNA repair in normal human keratinocytes co-exposed to benzo[a]pyrene and sunlight
Résumé
Skin has the potential to be exposed to both solar UV radiation and polycyclic aromatic hydrocarbons, especially
in occupational environments. In the present work, we investigated how benzo[a]pyrene (B[a]P) modulates
cellular phototoxicity and impacts formation and repair of pyrimidine dimers induced by simulated sunlight
(SSL) in normal human keratinocytes (NHK). We were especially interested in determining whether the aryl
hydrocarbon receptor (AhR) was involved since it was recently shown to negatively impact repair. Addition of
1 μM B[a]P after exposure to 2 minimal erythemal doses of SSL had little impact on NHK. The inverse protocol
involving incubation with B[a]P followed by irradiation led to a strong increase in phototoxicity. Repair of DNA
photoproducts was drastically impaired. Using agonists and antagonists of AhR allowed us to conclude that this
factor was not involved in these results. Observation of a strong increase in the level of the oxidative marker 8-
oxo-7,8-dihydroguanine in the protocol involving B[a]P treatment followed by exposure to SSL strongly suggested
that a photosensitized oxidative stress was responsible for cell death and inhibition of DNA repair.
Accordingly, both adverse effects were diminished with a lower concentration of B[a]P and a lower SSL dose,
leading to less oxidative stress.
Domaines
Biochimie [q-bio.BM]Origine | Fichiers produits par l'(les) auteur(s) |
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