Metabolomic Fingerprints of PAH Exposure - Identifying Toxicological Biomarkers in Dynamically Cultured 3D Cell Spheroids

Environmental exposure to polycyclic aromatic hydrocarbons (PAHs) causes metabolic dysfunction, but reliable biomarkers are still needed to assess human health effects. This study used 21-day matured human HepG2 spheroids, a metabolically competent three-dimensional (3D) liver model, to assess metabolic responses to graded, non-cytotoxic concentrations of benzo[a]pyrene (BaP) and benzo[b]fluoranthene (BBF) after 24- and 96-h exposure. Untargeted liquid chromatography-mass spectrometry (LC–MS) metabolomics, combined with multivariate and network analyses, identified compound- and time-specific metabolic signatures. At 24 hours, no metabolites showed significant changes. In contrast, at 96 hours, both PAHs consistently altered seven robust metabolites linked to polyamine metabolism, membrane dynamics, mitochondrial energy, and DNA-repair pathways. Network analysis showed BBF caused broader and more connected changes than BaP, indicating distinct toxicodynamics. These findings underscore the importance of extended exposure in revealing metabolic disruption and support a set of candidate biomarkers for future low-dose studies and improved risk assessment of airborne toxicants. ### Competing Interest Statement The authors have declared no competing interest. European Commission, https://ror.org/00k4n6c32, 101057497, 10050740 Croatian Science Foundation, https://ror.org/03n51vw80, MOBODL-2023-12-5502, MOBDOK-2023-1077 Slovenian Research Agency, https://ror.org/059bp8k51, P1-0245