A multi-omics approach reveals PFHxS as an environmental driver of gastric cancer via KEAP1 downregulation.

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants increasingly linked to human disease. Perfluorohexanesulfonic acid (PFHxS), a widespread PFAS detected in human serum, has an uncharacterized role in gastric cancer (GC), one of the leading causes of cancer mortality worldwide. Here, we employed an integrated multi-omics approach combining network toxicology, large-scale transcriptomic analyses from TCGA and GEO cohorts, single-cell RNA sequencing, and molecular simulations, followed by in vitro and in vivo validation at environmentally relevant concentrations. We identified 667 common targets of PFHxS and GC and developed an 11-gene gradient boosting machine (GBM) prognostic signature that robustly stratified patient survival across independent cohorts and correlated with distinct tumor immune microenvironments. Mechanistically, PFHxS was predicted and experimentally confirmed to directly bind Kelch-like ECH-associated protein 1 (KEAP1), a key regulator of oxidative stress. Chronic low-dose PFHxS exposure downregulated KEAP1 protein expression, disrupted KEAP1/NRF2 antioxidant signaling, and promoted GC cell proliferation, migration, invasion, and tumor growth in vivo. Together, these findings provide the first molecular evidence that PFHxS acts as an environmental driver of GC progression by targeting KEAP1, while also delivering a clinically relevant prognostic tool. This work highlights a previously unrecognized environmental risk factor for gastric cancer and offers new perspectives for risk assessment, prevention, and therapeutic intervention.