Dataset Information

Evidence for the aldo-keto reductase pathway of polycyclic aromatic trans-dihydrodiol activation in human lung A549 cells.

ABSTRACT: Polycyclic aromatic hydrocarbons (PAHs) are tobacco carcinogens implicated in the causation of human lung cancer. Metabolic activation is a key prerequisite for PAHs to cause their deleterious effects. Using human lung adenocarcinoma (A549) cells, we provide evidence for the metabolic activation of (+/-)-trans-7,8dihydroxy-7,8-dihydrobenzo[a]pyrene (B[a]P-7,8-trans-dihydrodiol) by aldo-keto reductases (AKRs) to yield benzo[a]pyrene-7,8-dione (B[a]P-7,8-dione), a redox-active o-quinone. We show that B[a]P-7,8-trans-dihydrodiol (AKR substrate) and B[a]P-7,8-dione (AKR product) lead to the production of intracellular reactive oxygen species (ROS) (measured as an increase in dichlorofluorescin diacetate fluores-cence) and that similar changes were not observed with the regioisomer (+/-)-trans-4,5-dihydroxy-4,5-dihydrobenzo[a]pyrene or the diol-epoxide, (+/-)-anti-7,8-dihydroxy-9alpha,10beta-epoxy-7,8,9,10-tetrahydro-B[a]P. B[a]P-7,8-trans-dihydrodiol and B[a]P-7,8-dione also caused a decrease in glutathione levels and an increase in NADP(+)/NADPH ratios, with a concomitant increase in single-strand breaks (as measured by the comet assay) and 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dGuo). The specificity of the comet assay was validated by coupling it to human 8-oxo-guanine glycosylase (hOGG1), which excises 8-oxo-Gua to yield single-strand breaks. The levels of 8-oxo-dGuo observed were confirmed by an immunoaffinity purification stable isotope dilution ([(15)N(5)]-8-oxo-dGuo) liquid chromatography-electrospray ionization/multiple reaction monitoring/mass spectrometry (LC-ESI/MRM/MS) assay. B[a]P-7,8-trans-dihydrodiol produced DNA strand breaks in the hOGG1-coupled comet assay as well as 8-oxo-dGuo (as measured by LC-ESI/MRM/MS) and was enhanced by a catechol O-methyl transferase (COMT) inhibitor, suggesting that COMT protects against o-quinone-mediated redox cycling. We conclude that activation of PAH-trans-dihydrodiols by AKRs in lung cells leads to ROS-mediated genotoxicity and contributes to lung carcinogenesis.

SUBMITTER: Park JH

PROVIDER: S-EPMC2383938 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Evidence for the aldo-keto reductase pathway of polycyclic aromatic trans-dihydrodiol activation in human lung A549 cells.

Park Jong-Heum JH Mangal Dipti D Tacka Kirk A KA Quinn Amy M AM Harvey Ronald G RG Blair Ian A IA Penning Trevor M TM

Proceedings of the National Academy of Sciences of the United States of America 20080512 19

Polycyclic aromatic hydrocarbons (PAHs) are tobacco carcinogens implicated in the causation of human lung cancer. Metabolic activation is a key prerequisite for PAHs to cause their deleterious effects. Using human lung adenocarcinoma (A549) cells, we provide evidence for the metabolic activation of (+/-)-trans-7,8dihydroxy-7,8-dihydrobenzo[a]pyrene (B[a]P-7,8-trans-dihydrodiol) by aldo-keto reductases (AKRs) to yield benzo[a]pyrene-7,8-dione (B[a]P-7,8-dione), a redox-active o-quinone. We show t ...[more]

PMID: 18474869

Similar Datasets

Project description:Aldo-keto reductases (AKRs) are phase I metabolising enzymes that catalyse the reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H)-dependent reduction of carbonyl groups to yield primary and secondary alcohols on a wide range of substrates, including aliphatic and aromatic aldehydes and ketones, ketoprostaglandins, ketosteroids and xenobiotics. In so doing they functionalise the carbonyl group for conjugation (phase II enzyme reactions). Although functionally diverse, AKRs form a protein superfamily based on their high sequence identity and common protein fold, the (alpha/beta) 8 -barrel structure. Well over 150 AKR enzymes, from diverse organisms, have been annotated so far and given systematic names according to a nomenclature that is based on multiple protein sequence alignment and degree of identity. Annotation of non-vertebrate AKRs at the National Center for Biotechnology Information or Vertebrate Genome Annotation (vega) database does not often include the systematic nomenclature name, so the most comprehensive overview of all annotated AKRs is found on the AKR website (http://www.med.upenn.edu/akr/). This site also hosts links to more detailed and specialised information (eg on crystal structures, gene expression and single nucleotide polymorphisms [SNPs]). The protein-based AKR nomenclature allows unambiguous identification of a given enzyme but does not reflect the wealth of genomic and transcriptomic variation that exists in the various databases. In this context, identification of putative new AKRs and their distinction from pseudogenes are challenging. This review provides a short summary of the characteristic features of AKR biochemistry and structure that have been reviewed in great detail elsewhere, and focuses mainly on nomenclature and database entries of human AKRs that so far have not been subject to systematic annotation. Recent developments in the annotation of SNP and transcript variance in AKRs are also summarised.

Project description:Aldo-keto reductase (AKR) 1C15, a member of the AKR superfamily, was recently identified and cloned, and reported to alleviate oxidative stress in endothelial cells in rodent lungs. However, its expression and role in the brain and ischemic brain diseases have not been investigated. AKR1C15 expression was detected with real-time PCR. Mouse ischemic stroke and ischemic preconditioning (IPC) were established with middle cerebral artery occlusion (MCAO) for 1 h or 12 min, respectively. Recombinant AKR1C15 was administered intraperitoneally, and stroke outcome was evaluated with neurobehavioral tests and infarct volumes. Rat primary brain cell cultures were subjected to oxygen-glucose deprivation (OGD) to mimic ischemic injury. Cell survival or in vitro blood-brain barrier (BBB) permeability was measured, and nitric oxide (NO) release was detected. Immunostaining and Western blotting were used to evaluate oxidative-stress-related protein expression. AKR1C15 administration decreased the infarct volume and neurological deficits 2d post-stroke, and its early (1-h) administration after IPC abolished the protection of IPC against stroke. In rat primary brain cell cultures, AKR1C15 was most abundantly expressed in brain microvascular endothelial cells (BMVECs) and microglia. Its expression decreased upon OGD in most cell types except for BMVECs and microglia. In primary neuronal cultures, AKR1C15 treatment prevented OGD-induced cell death accompanied by decreased levels of 4-hydroxynonenal, 8-hydroxy-2'-deoxyguanosine, and heme oxygenase-1. In BMVEC cultures, AKR1C15 treatment protected against OGD-induced cell death and in vitro BBB leakage. In primary microglial cultures, AKR1C15 reduced the release of NO upon proinflammatory stimulation. Our results provide a characterization of the novel antioxidant AKR1C15 and demonstrate its protective role against ischemic injury, both in vivo and in vitro. AKR1C15 may be a promising agent for ischemic stroke treatment.

Dataset Information

Evidence for the aldo-keto reductase pathway of polycyclic aromatic trans-dihydrodiol activation in human lung A549 cells.

Publications

Evidence for the aldo-keto reductase pathway of polycyclic aromatic trans-dihydrodiol activation in human lung A549 cells.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets