Airborne polycyclic aromatic compounds contribute to the induction of the tumour-suppressing P53 pathway in wild double-crested cormorants

• Published in: Ecotoxicology and environmental safety 2018-04, Vol.150, p.176-189
• Main Authors: Wallace, S.J., de Solla, S.R., Thomas, P.J., Harner, T., Eng, A., Langlois, V.S.
• Format: Article
• Language: English
• Subjects: Birds; DNA methylation; Gene expression; Polycyclic aromatic compounds; Protein expression; Toxicity
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2017.12.028

Polycyclic aromatic compounds (PACs), including polycyclic aromatic hydrocarbons (PAHs) and PAH-like compounds are known or probable environmental carcinogens released into the environment as a by-product of incomplete combustion of fossil fuels and other organic materials. Studies have shown that exposure to PACs in the environment can induce both genotoxicity and epigenetic toxicity, but few studies have related PAC exposure to molecular changes in free ranging wildlife. Previous work has suggested that double-crested cormorants (Phalacrocorax auritus; DCCO) exhibited a higher incidence of genetic mutations when their breeding sites were located in heavily industrialized areas (e.g., Hamilton Harbour, Hamilton, ON, Canada) as compared to sites located in more pristine environments, such as in Lake Erie. The aim of this study was to determine if airborne PACs from Hamilton Harbour alter the tumour-suppressing P53 pathway and/or global DNA methylation in DCCOs. Airborne PACs were measured using passive air samplers in the Hamilton Harbour area and low-resolution mass spectrometry analysis detected PACs in livers of DCCOs living in Hamilton Harbour. Further hepatic and lung transcriptional analysis demonstrated that the expression of the genes involved in the DNA repair and cellular apoptosis pathway were up-regulated in both tissues of DCCOs exposed to PACs, while genes involved in p53 regulation were down-regulated. However, global methylation levels did not differ between reference- and PAC-exposed DCCOs. Altogether, data suggest that PACs activate the P53 pathway in free-ranging DCCOs living nearby PAC-contaminated areas. •Wild double-crested cormorants in Hamilton Harbour are exposed to airborne PACs.•PACs were detected at higher levels in liver tissue with higher PAC exposure.•Genes in the tumour-suppressing P53 pathway were altered in liver and lung tissue.•DNA repair and apoptopic pathways were upregulated with PAC exposure.•Global DNA methylation levels were variable and did not differ with PAC exposure.