Comparative transcriptomic points of departure analysis of pesticides in human Caco-2 and Hep G2 cells.

Transcriptomic data capture early molecular perturbations and can be used to derive transcriptomic points of departure (tPODs) as potential alternatives to apical points of departure (PODs) from animal studies. This study aimed to derive tPODs for 19 pesticides of environmental concern using two human cell lines relevant to oral exposure, Caco-2 and Hep G2, and to compare the results with in vivo toxicity data and regulatory thresholds. tPODs were successfully obtained for all pesticides, ranging from 0.032 to 880 µM. Pathway analysis indicated more stress-related responses in Caco-2 cells, whereas more metabolic pathways were identified in Hep G2 cells. Following mass balance modeling and in vitro-in vivo extrapolation, tPODs were converted to human administered equivalent doses (t-AEDs). In Hep G2 cells, approximately 70% of t-AEDs were within one order of magnitude of corresponding PODs from chronic animal studies, suggesting moderate concordance. Transcriptomic reference values (t-TRVs) were derived from t-AEDs to compare with regulatory thresholds. Although correlations were weak, the overall trends suggest that short-term in vitro tPODs may provide conservative estimates relative to apical endpoints. Overall, this workflow demonstrates the potential of in vitro transcriptomics to generate quantitative and mechanistic data to support chemical screening and prioritization in risk assessment.