Genotoxicity but not the AhR-mediated activity of PAHs is inhibited by other components of complex mixtures of ambient air pollutants

Abstract

In this study, we compared the genotoxicity and aryl hydrocarbon receptor (AhR)-dependent transcriptional changes of selected target genes in human lung epithelial A549 cells incubated for 24 h, either with extractable organic matter (EOMs) from airborne particles <2.5 μm (PM2.5) collected at four localities from heavily polluted areas of the Czech Republic or two representative toxic polycyclic aromatic hydrocarbons (PAHs) present in EOMs, benzo[a]pyrene (B[a]P) and benzo[k]fluoranthene (B[k]F). Genotoxic effects were determined using DNA adduct analysis or analysis of expression of selected AhR-related genes involved in bioactivation of PAHs (CYP1A1, CYP1B1) and transcriptional repression (TIPARP). Sampled localities differing in the extent and source of air pollution did not exhibit substantially different genotoxicity. DNA adduct levels induced by three subtoxic EOM concentrations were relatively low (1-5 adducts/10(8) nucleotides), compared to levels induced by similar concentrations of B[a]P, while B[k]F gave very low DNA adduct levels. Here, we compared genotoxicity and gene deregulation induced by complex mixtures containing PAHs with the effects of the comparable concentrations of individual PAHs. Our results suggested inhibition of formation of B[a]P-induced DNA adducts compared to individual B[a]P, probably attributable to competitive inhibition by other non-genotoxic EOM components. In contrast, induction of AhR target genes appeared not to be antagonized by the components of complex mixtures, as induction of CYP1A1, CYP1B1 and TIPARP transcripts reached maximum levels induced by PAHs.

Analysis of gene expression changes in A549 cells induced by organic compounds from respirable air particles

“…In our previous studies, we have focused on comparison of genotoxic dose-responses (determined as DNA adduct formation) with induction of AhR activation in A549 cells [7] and global gene expression in human lung fibroblasts HEL cells treated with the same set of EOM samples [6]. Here, we attempted to identify gene expression changes induced in human alveolar carcinoma A549 cells by a complex mixture of air pollutants adsorbed on PM2.5, and to compare the effects of EOMs originating from distinct localities and sources.…”

“…In this study numerous biological processes and signaling pathways have been found to be deregulated in response to various organic extracts from PM2.5, and the key role of the activated AhR has been identified. In a follow-up study, performed in human lung epithelial adenocarcinoma cells A549, we have further observed that EOM-induced DNA adduct levels are relatively low, as compared to levels induced by similar concentrations of benzo[a]pyrene (B[a]P) [7]. We suggested that this might be due to competitive inhibitory effects of some non-genotoxic EOM components requiring identical enzymatic activities for their metabolism as genotoxic PAHs, which are mostly responsible for DNA adduct formation by EOM [8].…”

“…PM collection, extraction of organic matter and chemical characterization has been extensively described in our previous studies [6,7]. The basic characteristics of PM2.5 sampling are shown in Table 3.…”

Combined exposure to nano-silica and lead induced potentiation of oxidative stress and DNA damage in human lung epithelial cells

“…Human lung cell lines are routinely used to assess the toxicities of PM and mixture of ambient air pollutants (Deng et al, 2014;Líbalová et al, 2014;Michael et al, 2013;Yu et al, 2015). However, effects of exposure to a combination of Pb, a typical air pollutant, and silica, a typical UFP, are unclear.…”

Cytotoxicity properties of PM2.5 collected in Wrocław agglomeration

“…This fact is the reason that the colour of the samples can disturb results of spectrophotometer reading at wavelength 340 nm. Described problem is not presented in publications conducted by other authors on A549 cell line, but the testing procedure in this cases is different from PAN-I instruction [12][13][14].…”