Long-Chain Hexafluoropropylene Oxide Homologues Impair Trophoblast Function via Integrin-Mediated FAK/PI3K/Akt Suppression and Mitochondrial Dysfunction

Abstract Emerging per- and polyfluoroalkyl substance alternatives, including hexafluoropropylene oxide (HFPO) homologues, are increasingly detected in environmental and biological systems, yet their structure-dependent toxicity mechanisms remain poorly understood. Here, we demonstrate that long-chain HFPOs (HFPO-TA and HFPO-TeA), but not short-chain HFPO-DA or PFOA, induce pronounced toxicity in human trophoblast-like HTR-8/SVneo cells, characterized by suppressed proliferation, S-phase cell cycle arrest, and impaired migration and invasion. Transcriptomic profiling revealed selective disruption of integrin-mediated adhesion and focal adhesion signaling pathways, accompanied by activation of cellular stress responses. Consistently, long-chain HFPOs disrupted focal adhesion assembly and inhibited FAK/PI3K/Akt signaling, while simultaneously inducing mitochondrial dysfunction and excessive reactive oxygen species production. Molecular docking suggested preferential interactions between HFPO-TeA and integrin subunits, supporting a potential structure-dependent interaction mechanism. Pharmacological activation of FAK partially restored cytoskeletal organization, indicating a central role of adhesion signaling in mediating toxicity. Collectively, this study establishes a mechanistic framework linking fluorinated carbon chain length to integrin-centered adhesion signaling and mitochondrial dysfunction, advancing our understanding of how structural variation among PFAS alternatives drives cell type-specific toxicity and providing a basis for evaluating the developmental and reproductive risks of emerging PFAS substitutes.