Hazard assessment of air pollutants: The transforming ability of complex pollutant mixtures in the Bhas 42 cell model.

Stefania Serra

doi:10.14573/altex.1812173

Abstract

The use of in vitro alternative methods is a promising approach to characterize the hazardous properties of environmental chemical mixtures, including urban airborne particulate matter (PM). The aim of this study was to examine seasonal differences in the toxic and transforming potential of PM samples, by using the in vitro cell transformation assay in Bhas 42 cells for the prediction of potential carcinogenic effects. Bhas 42 cells are already initiated, and the v-Ha-ras transfection, together with genetic modification following the immortalization process, makes them a valuable model to study the late steps of cellular transformation leading to the acquisition of the malignant phenotype. Exposure to organic extracts of PM1 and PM2.5 induced dose-related effects. The transforming and cytotoxic properties are related to the amount of PM collected during the sampling campaign and associated with the concentrations of polycyclic aromatic hydrocarbons (PAHs) in the samples. All the samples induced cell transformation following prolonged exposure of 2 weeks. Our results support the utility of the in vitro top-down approach to characterise the toxicity of real mixtures, thereby supporting regulators in the decision-making process. The results also identify the need for appropriate assay selection within the in vitro testing strategy to address the complexity of the final adverse outcomes.

Highlights

Air pollution is known to increase the risk for a wide range of adverse health outcomes (Landrigan et al, 2018; WHO, 2016)
Frozen Bhas 42 cells were rapidly thawed and cultured in M10F up to about 70% confluence and cultured in Dulbecco’s modified Eagle’s medium/Ham’s F12 supplemented with 100 units/ml of penicillin, 100 μg/ml of streptomycin, and 5% fetal bovine serum (FBS) (DF5F) to let cells reach about 70% confluence again, before seeding them for the cell transformation assay (CTA)
Even though the CTA cannot be used as a stand-alone test for predicting carcinogenesis, it can address both genotoxic and some non-genotoxic carcinogenic modes of action

Summary

Introduction

Air pollution is known to increase the risk for a wide range of adverse health outcomes (Landrigan et al, 2018; WHO, 2016). In 2013, the International Agency for Research on Cancer (IARC) classified outdoor air pollution and particulate matter (PM) from outdoor air pollution as carcinogenic to humans (Group 1) (Loomis et al, 2013; IARC, 2016). This evaluation is based on sufficient evidence of carcinogenicity in humans and experimental animals (IARC, 2016). Epidemiological studies have demonstrated a clear association between lifetime exposure to PM and lung cancer (Gharibvand et al, 2017; Hamra et al, 2014) This evidence is supported by strong mechanistic data, demonstrating the induction of mutagenic and genotoxic effects in humans and experimental systems (IARC, 2016). PM can play a role in the non-genotoxic origin of cancer, through the induction of oxidative stress-sustained inflammation (IARC, 2016)

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