Genetic evidence and multi-omics characterization of DEHP-relevant detoxification and metabolic heterogeneity in hepatocellular carcinoma

Background: Human evidence linking di(2-ethylhexyl) phthalate (DEHP) exposure to hepatocellular carcinoma (HCC) is limited, and it remains unclear whether DEHP-relevant detoxification biology captures clinically meaningful HCC heterogeneity. Methods: We integrated two-sample Mendelian randomization, proteomic and phosphoproteomic subtyping, bulk, single-cell and spatial transcriptomics, computational candidate prioritization, molecular docking, and cell-based assays. Genetically proxied MECPP and MEHHP were evaluated for associations with HCC and liver-related outcomes. DPTS-related molecular, cellular, spatial, and experimental patterns were then characterized. Results: MR did not support a causal association of genetically proxied MECPP or MEHHP with HCC. In 165 CPTAC tumors, consensus clustering identified two detoxification-phosphorylation tumor subtypes. Compared with DPTS1, DPTS2 showed coordinated suppression of xenobiotic metabolism, bile acid metabolism, fatty-acid oxidation, phase II conjugation, and transport programs. A transcriptomically projected DPTS2-like state was associated with poorer overall survival in TCGA-LIHC, but this association was not replicated in ICGC-LIRI-JP. Single-cell and spatial analyses localized these programs mainly to hepatocyte-like compartments and showed modest spatial coordination with nine prioritized genes, including ALDH2, EHHADH, and PCK2. LINCS-based screening and molecular docking prioritized PD-0325901, trametinib, and regorafenib, but these predictions did not demonstrate binding or efficacy, and the compounds were not tested experimentally. Basal qPCR and DEHP-treatment experiments showed cell-line-specific expression and phenotypic responses. Conclusion: DPTS defines a DEHP-relevant, detoxification-suppressed HCC molecular phenotype rather than an exposure-defined or DEHP-induced subtype. These findings provide a bounded framework for future mechanistic validation of metabolic vulnerability in HCC.