Pathway and Time-Resolved Benzo[a]pyrene Toxicity on Hepa1c1c7 Cells at Toxic and Subtoxic Exposure

Abstract

Benzo[a]pyrene (B[a]P) is an environmental contaminant mainly studied for its toxic/carcinogenic effects. For a comprehensive and pathway orientated mechanistic understanding of the effects directly triggered by a toxic (5 μM) or a subtoxic (50 nM) concentration of B[a]P or indirectly by its metabolites, we conducted time series experiments for up to 24 h to study the effects in murine hepatocytes. These cells rapidly take up and actively metabolize B[a]P, which was followed by quantitative analysis of the concentration of intracellular B[a]P and seven representative degradation products. Exposure with 5 μM B[a]P led to a maximal intracellular concentration of 1604 pmol/5 × 10(4) cells, leveling at 55 pmol/5 × 10(4) cells by the end of the time course. Changes in the global proteome (>1000 protein profiles) and metabolome (163 metabolites) were assessed in combination with B[a]P degradation. Abundance profiles of 236 (both concentrations), 190 (only 5 μM), and 150 (only 50 nM) proteins were found to be regulated in response to B[a]P in a time-dependent manner. At the endogenous metabolite level amino acids, acylcarnitines and glycerophospholipids were particularly affected by B[a]P. The comprehensive chemical, proteome and metabolomic data enabled the identification of effects on the pathway level in a time-resolved manner. So in addition to known alterations, also protein synthesis, lipid metabolism, and membrane dysfunction were identified as B[a]P specific effects.

Environmental carcinogenesis and pH homeostasis: Not only a matter of dysregulated metabolism

“…At these high concentrations, the p53 pathway would be predominant due to important DNA damages. This illustrates that different signaling pathways are triggered at different B[a]P concentrations, thus resulting in different mechanisms for toxicity as also reported by others [109,171].…”

Metabolomic analysis to define and compare the effects of PAHs and oxygenated PAHs in developing zebrafish

“…However, the exact mechanism by which PAHs alter the aa-tRNA pathway was not identified. Shen and Yu (2008) and Kalkhof et al (2014) found that a similar decreased in protein synthesis was associated with exposure to with B[a]P and a B[a]P metabolite. Their results showed that most subunits of eukaryotic translation initiation factors (EIFs) and involved proteins were down-regulated after 24 h of exposures.…”

Prospects and challenges of multi-omics data integration in toxicology

“…Several multi-omics studies, particularly dual-omics studies, for toxicological research questions have been published, e.g., on nanomaterials (Scala et al 2018 (Kalkhof et al 2015). The diXA project has assembled a set of toxicogenomics studies from diverse sources, which in part comprise multi-omics data (Hendrickx et al 2015).…”

“…Transcriptome data were measured with Affymetrix GeneChips by Michaelson et al (2011). SILAC-based proteomics and targeted metabolomics data were conducted by Kalkhof et al (2015). All experiments were generated from different replicates.…”