Acidic extracellular and intracellular pH modifies benzo[a]pyrene induced DNA damage and repair
-
1
School for Nutrition and Translational Research in Metabolism at Maastricht University, Pharmacology & Toxicology, Netherlands
Chronic inflammation creates an acidic microenvironment, which may play an important role in cancer development. To investigate how a low pH may change the cellular response to the environmental carcinogen benzo[a]pyrene (B[a]P), we exposed human pulmonary epithelial cells (A549) to non-toxic doses of 1µM B[a]P at various extracellular pH’s (pHe = 7.8, 7.0, 6.5, 6.0 and 5.5) for 6, 24 and 48 hours. In most incubations (pHe 7.0- 6.5), the pH restored to pH 7.8 after 48 hours of exposure. However, at the lowest pH (pHe< 6.0), this recovery was imcomplete and only reached to pH 6.5 at t=48 h. Similar changes were observed for the intracellular pH (pHi). The acidic pH delayed the metabolism of B[a]P and at t=48 h, the concentrations of unmetabolised extracellular B[a]P was 60-fold higher at pHe 5.5 than at normal pH (pHe 7.8). However, the concentration of the pre-mutagenic metabolite B[a]P-7,8-diol was 955-fold increased at pHe 5.5 when compared to exposure to B[a]P at pHe 7.8 at 48 hours. Cytochrome P450 (CYP1A1) expression and its activity (assessed as ethoxyresorufin-O-deethylase (EROD) activity) were initially repressed at low pHe, but then significantly increased at later later time points (48 hours) when compared to normal pHe. In addition, the nucleotide excision repair (NER) capacity, assessed by a modified Comet assay, was ~80% inhibited at pH 5.5 at 6 hours after exposure to B[a]P. However at t=48 h, the NER capacity recovered to 100% of the initial repair activity observed at pHe=7.8. Eventually, 6 times higher B[a]P-DNA adduct levels were observed at low pHe than at pHe 7.8. Overall, our data suggest that acidic pH delayed the metabolism of B[a]P and inhibited DNA repair, which increased B[a]P induced DNA damage.
Keywords:
acidic ph,
benzo[a]pyrene,
Cytochrome P450 (CYP1A1),
DNA Adducts,
DNA Repair
Conference:
ICAW 2015 - 11th International Comet Assay Workshop, Antwerpen, Belgium, 1 Sep - 4 Sep, 2015.
Presentation Type:
Poster Presentation
Topic:
Clinical applications of the comet assay
Citation:
Shi
Q,
Maas
L,
Van Schooten
FJ and
Godschalk
R
(2015). Acidic extracellular and intracellular pH modifies benzo[a]pyrene induced DNA damage and repair.
Front. Genet.
Conference Abstract:
ICAW 2015 - 11th International Comet Assay Workshop.
doi: 10.3389/conf.fgene.2015.01.00002
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
23 Jun 2015;
Published Online:
23 Jun 2015.
*
Correspondence:
Dr. Roger Godschalk, School for Nutrition and Translational Research in Metabolism at Maastricht University, Pharmacology & Toxicology, Maastricht, 6200MD, Netherlands, r.godschalk@maastrichtuniversity.nl