title: Effects of defined mixtures of persistent organic pollutants (POPs) on multiple cellular responses in the human hepatocarcinoma cell line, HepG2, using high content analysis screening.
abstract: Persistent organic pollutants (POPs) are toxic substances, highly resistant to environmental degradation, which can bio-accumulate and have long-range atmospheric transport potential. Most studies focus on single compound effects, however as humans are exposed to several POPs simultaneously, investigating exposure effects of real life POP mixtures on human health is necessary. A defined mixture of POPs was used, where the compound concentration reflected its contribution to the levels seen in Scandinavian human serum (total mix). Several sub mixtures representing different classes of POPs were also constructed. The perfluorinated (PFC) mixture contained six perfluorinated compounds, brominated (Br) mixture contained seven brominated compounds, chlorinated (Cl) mixture contained polychlorinated biphenyls and also p,p'-dichlorodiphenyldichloroethylene, hexachlorobenzene, three chlordanes, three hexachlorocyclohexanes and dieldrin. Human hepatocarcinoma (HepG2) cells were used for 2h and 48h exposures to the seven mixtures and analysis on a CellInsight™ NXT High Content Screening platform. Multiple cytotoxic endpoints were investigated: cell number, nuclear intensity and area, mitochondrial mass and membrane potential (MMP) and reactive oxygen species (ROS). Both the Br and Cl mixtures induced ROS production but did not lead to apoptosis. The PFC mixture induced ROS production and likely induced cell apoptosis accompanied by the dissipation of MMP. Synergistic effects were evident for ROS induction when cells were exposed to the PFC+Br mixture in comparison to the effects of the individual mixtures. No significant effects were detected in the Br+Cl, PFC+Cl or total mixtures, which contain the same concentrations of chlorinated compounds as the Cl mixture plus additional compounds; highlighting the need for further exploration of POP mixtures in risk assessment.
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Jodie
authors.initials: J
authors.lastname: Wilson
authors.affiliation: Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Hanne Friis
authors.initials: HF
authors.lastname: Berntsen
authors.affiliation: Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Karin Elisabeth
authors.initials: KE
authors.lastname: Zimmer
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Caroline
authors.initials: C
authors.lastname: Frizzell
authors.affiliation: Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Steven
authors.initials: S
authors.lastname: Verhaegen
authors.affiliation: Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Erik
authors.initials: E
authors.lastname: Ropstad
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Northern Ireland, United Kingdom. Electronic address: l.connolly@qub.ac.uk.
authors.forename: Lisa
authors.initials: L
authors.lastname: Connolly
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D045424:Complex Mixtures / Q000633:toxicity; D004785:Environmental Pollutants / Q000633:toxicity*; D005466:Fluorocarbons / Q000633:toxicity; D056945:Hep G2 Cells; D057166:High-Throughput Screening Assays; D006801:Humans; D006842:Hydrocarbons, Brominated / Q000633:toxicity; D006843:Hydrocarbons, Chlorinated / Q000633:toxicity; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008930:Mitochondria, Liver / Q000187:drug effects / Q000648:ultrastructure; D009930:Organic Chemicals / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D045424:Complex Mixtures; D004785:Environmental Pollutants; D005466:Fluorocarbons; D006842:Hydrocarbons, Brominated; D006843:Hydrocarbons, Chlorinated; D009930:Organic Chemicals; D017382:Reactive Oxygen Species
keywords: Cytotoxicity; High content analysis; Mixtures; Persistent organic pollutants