Nucleotide Excision Repair Is Not Induced in Human Embryonic Lung Fibroblasts Treated with Environmental Pollutants

Pavel Rossner,Radim J Sram,Katerina Uhlirova,Alena Milcova,Helena Libalova,Jan Topinka,Andrea Rossnerova,Jana Schmuczerova,Andrea Mrhalkova,Milada Spatova,Rory Edward Morty

doi:10.1371/journal.pone.0069197

Abstract

The cellular response to genotoxic treatment depends on the cell line used. Although tumor cell lines are widely used for genotoxicity tests, the interpretation of the results may be potentially hampered by changes in cellular processes caused by malignant transformation. In our study we used normal human embryonic lung fibroblasts (HEL12469 cells) and tested their response to treatment with benzo[a]pyrene (B[a]P) and extractable organic matter (EOM) from ambient air particles <2.5 µm (PM2.5) collected in two Czech cities differing in levels and sources of air pollution. We analyzed multiple endpoints associated with exposure to polycyclic aromatic hydrocarbons (PAHs) including the levels of bulky DNA adducts and the nucleotide excision repair (NER) response [expression of XPE, XPC and XPA genes on the level of mRNA and proteins, unscheduled DNA synthesis (UDS)]. EOMs were collected in the winter and summer of 2011 in two Czech cities with different levels and sources of air pollution. The effects of the studied compounds were analyzed in the presence (+S9) and absence (–S9) of the rat liver microsomal S9 fraction. The levels of bulky DNA adducts were highest after treatment with B[a]P, followed by winter EOMs; their induction by summer EOMs was weak. The induction of both mRNA and protein expression was observed, with the most pronounced effects after treatment with B[a]P (–S9); the response induced by EOMs from both cities and seasons was substantially weaker. The expression of DNA repair genes was not accompanied by the induction of UDS activity. In summary, our results indicate that the tested compounds induced low levels of DNA damage and affected the expression of NER genes; however, nucleotide excision repair was not induced.

Highlights

Particulate matter (PM) is a ubiquitous air pollutant that originates in the environment either as primary particles emitted directly into the atmosphere, or as secondary particles formed as a result of chemical reactions between gaseous pollutants or reactions between gases and primary particles [1]
Air Sampling and Chemical Analysis of extractable organic matter (EOM) Air sampling was conducted in two locations: in Prague, the capital of the Czech Republic, and in Ostrava, an industrial city in Northeastern Moravia characterized by high concentrations of PM2.5 and polycyclic aromatic hydrocarbons (PAHs) pollution in the ambient air (Table 1, 2)
Chemical analysis of eight selected PAHs revealed that the concentrations of these compounds in EOMs differed (Table 2): total PAH concentrations were significantly higher in the Ostrava-winter than in the Praguewinter EOM and in the Ostrava-summer than in the Praguesummer EOM (p,0.001)

Summary

Introduction

Particulate matter (PM) is a ubiquitous air pollutant that originates in the environment either as primary particles emitted directly into the atmosphere, or as secondary particles formed as a result of chemical reactions between gaseous pollutants or reactions between gases and primary particles [1]. Human exposure to PM is associated with increased mortality, due to cardiovascular and respiratory diseases, including cancer [2,3]. The major components of PM are organic compounds including polycyclic aromatic hydrocarbons (PAHs), quinones, transition metals, reactive gases, biological material, and minerals [2]. The carcinogenic properties of PM2.5 are namely associated with the presence of known carcinogens, including PAHs, arsenic, chromium, and nickel, other constituents of PM2.5 may play a role in tumor induction by this mixture [4]

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