Identifying a Suitable Human Hepatic In Vitro Model to Study Aryl Hydrocarbon Receptor-Mediated CYP1A1 and CYP1A2 Expression.

The aryl hydrocarbon receptor (AHR) is a central mediator of cellular responses to environmental exposures, including cigarette smoke. Appropriate selection of in vitro hepatic models is critical for investigating AHR-dependent induction of xenobiotic-metabolizing enzymes. Therefore, The aim of this study was to compare AHR-mediated induction of CYP1A1 and CYP1A2 across five human hepatic in vitro models to identify the most suitable model. Primary human hepatocytes (PHH), HepaRG, HepG2, HuH-7, and upcyte® hepatocytes were exposed to cigarette smoke extract and prototypical CYP inducers, responses were assessed at mRNA and enzyme activity levels. PHH confirmed their role as gold standard model, while HepaRG cells emerged as practical and ethical alternative for mechanistic studies. HepG2 and HuH-7 showed limited responsiveness. Upcyte® hepatocytes displayed strongly elevated fold changes, compared to other models. Overall, pronounced model-specific differences in AHR responsiveness emphasize the importance of informed in vitro model selection for exposure-relevant studies. By directly contrasting transcript and functional activity endpoints across five models, this work clarifies strengths and limitations that are often not apparent in single-model studies. Therefore, this work provides practical guidance for informed model selection in studies of the AHR signaling pathway.