Approved Abstracts

Interaction mechanisms of Polycyclic Aromatic Hydrocarbons in fish primary hepatocyte cell: from molecular to genotoxic toxic effects



Author(s): Bramatti IC; Matos B; Figueiredo N; Branco V; Martins M;
Presenter: Isabella Calvo Bramatti

Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous contaminants existing as complex mixtures in aquatic ecosystems. These organic compounds can be metabolized or bioactivated via specific cytochrome P450 (CYP) enzymes and be conjugated to glutathione by cytosolic glutathione S- transferases (GSTs), a family of isoenzymes distributed predominantly in the liver. However, during this PAH metabolism, more reactive metabolites could be formed, and some of which can damage DNA and proteins. The individual PAHs may hold very distinct mechanisms of toxicity, regardless of chemical similarities among the class. Moreover, the integrations effects between them are poorly understood, compromising the ecological realism and the environmental quality guidelines which are based on the toxicity of single PAHs. Fish are widely used as a biological model for the evaluation of ecotoxicity and environmental risk. Hence, in vitro relevant models arise as important tools for mechanistic screening before validation in vivo. The present work aimed at understanding the interaction effects between carcinogenic and non-carcinogenic PAHs in primary hepatocytes of S. aurata, considering ecologically-relevant mixture and concentrations of benzo[a]pyrene, benzo[b]fluoranthene and phenanthrene. After 24h and 48h of exposure, responses related to detoxification (e.g. induction of CYP1A, Glutathione -S-Transferase activity, transcriptional responses, e.g. epoxihydrolase) and their correlation to genotoxicity, were assessed in primary hepatocyte cells. The results showed that, for all treatments, there was a time- and concentration dependent increase of CYP1A expression and GST activity. Genotoxicity was related with the processes of detoxification. Moreover, PAHs interactions yield toxicological responses that are difficult to assess by single PAH exposures, and may greatly alter the final outcome. Thus, these results showed the importance of disclose interaction effects of these anthropogenic pollutants in order to improve the environmental quality guidelines.

This work was supported by PAHMIX project - Mixtures of Environmental Carcinogens: a molecular approach to improve environmental risk assessment strategies (PTDC/CTA-AMB/29173/2017) and the Marine and Environmental Sciences Centre —MARE (UIDB/04292/2020; UIDP/04292/2020), both financed by national funds from Fundação para a Ciência e Tecnologia (FCT; www.fct.pt). Vasco Branco is financed by national funds via FCT, I.P. through Norma Transitória -DL57/2016/CP1376/CT002. Marta Martins is financed through FCT, I.P., under the Scientific Employment Stimulus—Institutional Call (CEECINST/00102/2018).

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