# Metabolic activation of nitroarenes and Nrf2-Keap1

> **NIH NIH R01** · UNIVERSITY OF PENNSYLVANIA · 2021 · $468,766

## Abstract

ABSTRACT
METABOLIC ACTIVATION OF NITROARENES AND NRF2-KEAP1
Diesel exhaust contains unique nitroarenes (NO2-PAH) that contribute to the incidence of lung cancer caused
by air pollution. Only a subset of individuals exposed to air pollutants succumbs to lung cancer suggesting that
a significant gene-environment interaction exists. Individual susceptibility to NO2-PAH may be driven by intrinsic
genotypes, non-synonymous single nucleotide polymorphisms (nsSNPs) that change the function of genes
involved in their metabolic activation, while acquired susceptibility may be driven by persistent (transcriptomic)
changes in the expression of the same genes. Identification of these genes is thus of paramount importance to
risk stratify individuals for lung cancer screening. Genes most implicated in the metabolic activation of NO2-PAH
are those that exhibit nitroreductase activity e.g. NADPH-Quinone Oxidoreductase (NQO1). However, our
preliminary data shows that human Aldo-Keto Reductases (AKR1C1-AKR1C3) exhibit nitroreductase activity
and may be involved in the metabolic activation of NO2-PAH. NQO1 is a prototypic Nrf2-regulated gene, but the
AKR1C1 genes are among the most upregulated by Nrf2-Keap1 in humans yet the least studied. Induction of
these genes by air pollutants, and by the electrophiles and reactive oxygen species they generate, could create
a vicious circle whereby NO2-PAH exacerbate their own genotoxicity. Our hypothesis is that AKRs are
involved in the metabolic activation of NO2-PAH; that the induction of NQO1 and AKR1C genes by Nrf2
increases NO2-PAH derived DNA adduct formation; that intrinsic susceptibility to NO2-PAH is dependent
upon common AKR1C nsSNPs and that acquired susceptibility to NO2-PAH is determined by a
hyperactive Nrf2-Keap1 pathway. Our hypothesis will be tested as follows: In Aim 1, we will test whether AKRs
catalyze the nitroreduction of a panel of nitroarenes found in diesel exhaust e.g. 3-nitrobenzanthrone (3-NBA),
6-nitrochrysene (6-NC), 1-nitropyrene and 1,8-dinitropyrene. Product profiling will be performed by UPLC-ion
trap mass spectrometry. In Aim 2, we will test whether upregulation of NQO1 and AKRs by Nrf2 activators and
air pollutants exacerbate NO2-PAH activation in normal human bronchial epithelial (HBEC-kt) cells. We will
determine whether increases in 3-NBA and 6-NC derived DNA adducts, measured by stable-isotope dilution
liquid chromatography tandem mass spectrometry, are mediated by NQO1 and AKR1C induction. In Aim 3, we
will determine: a) whether common allelic variants in AKR1C genes result in reduced nitroreductase activity to
lower intrinsic susceptibility to NO2-PAH; b) whether acquired susceptibility to NO2-PAH is dependent upon
hyperactive Nrf2 by measuring NO2-PAH derived DNA adducts in human lung adenocarcinoma (A549) cells in
which the KEAP1 promoter is hypermethylated, and in A549 cells in which Nrf2 has been knocked-down by
CRISPR/ Cas9; and c) whether HBEC-kt cells that are sensitive to Nrf...

## Key facts

- **NIH application ID:** 10178027
- **Project number:** 5R01ES029294-03
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** KARAM E EL-BAYOUMY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $468,766
- **Award type:** 5
- **Project period:** 2019-05-08 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10178027

## Citation

> US National Institutes of Health, RePORTER application 10178027, Metabolic activation of nitroarenes and Nrf2-Keap1 (5R01ES029294-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10178027. Licensed CC0.

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