RUNX3 DNA methylation as a novel biomarker for PFAS-induced genotoxicity: Insights into 6:2 FTSA-mediated epigenetic dysregulation.

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) represent a persistent class of environmental contaminants associated with adverse health outcomes, though their genotoxic mechanisms remain poorly characterized.

METHODS

This study investigated dose-response relationships and molecular pathways linking PFAS exposure to DNA damage in 168 healthy individuals without occupational exposure, focusing on the role of RUNX3 DNA methylation. Among 23 PFAS analyzed, 21 were quantifiable in serum.

RESULTS

Higher PFAS concentrations correlated significantly with elevated Tail DNA% (P < 0.05) and increased RUNX3 DNA methylation. Bayesian Kernel Machine Regression (BKMR) model revealed that PFAS mixture at the 75th percentile, compared to the 50th, were associated with a 3.115 (95% CI: 0.765, 5.465) increase in Tail DNA% and a 0.834 (95% CI: 0.265, 1.403) increase in RUNX3 DNA methylation. Of all PFAS components, 6:2 fluorotelomer sulfonate (6:2 FTSA) showed the strongest associations with DNA damage (PIP = 0.69) and RUNX3 methylation (PIP = 0.99). Mediation analysis indicated that 6:2 FTSA influenced RUNX3 DNA methylation partly through DNA damage, accounting for 11.6% of the total effect (P < 0.05). Molecular docking suggested 6:2 FTSA may interact with DNA methyltransferase (DNMT1, DNMT3A/B). These population-level findings were further supported by in vitro experiments in primary peripheral blood mononuclear cells (PBMCs), where 6:2 FTSA exposure dose-dependently increased DNA damage and reduced RUNX3 mRNA expression via DNA hypermethylation.

CONCLUSIONS

Overall, our results implicate RUNX3 hypermethylation plays a key role in PFAS-induced genotoxicity, with 6:2 FTSA identified as a key contributor. RUNX3 methylation may therefore serve as a sensitive epigenetic biomarker for early detection of PFAS-associated DNA damage, particularly relevant for monitoring emerging compounds such as 6:2 FTSA.