Perfluorobutanoic acid: a short-chain perfluoroalkyl substance exhibiting estrogenic effects through the estrogen-related receptor γ pathways

Perfluorobutanoic acid (PFBA) is an emerging contaminant that was demonstrated to exhibit estrogen effects via action on classic estrogen receptors (ERs) in a low-activity manner. The purpose of the present study is to reveal the estrogen disruption effect and mechanism of PFBA via estrogen-related receptors γ (ERRγ) pathways. In vivo experiment indicated that PFBA accumulated in zebrafish ovary and caused ovarian injury, with disturbing sex hormone levels and interfering gene expression related to estrogen synthesis and follicle regulation. In vitro, with cell proliferation assay, PFBA could promote estrogen-sensitive endometrial cancer cell Ishikawa proliferation at lowest observed effective concentrations (LOEC) 10 nM, which was close to human exposure levels. And cell proliferation was inhibited by ERRγ antagonist GSK5182. By fluorescence competitive binding assay, molecular docking and luciferase reporter gene assays, it demonstrated that PFBA could directly bind with ERRγ and activate ERRγ transcriptional activities with a LOEC of 10 nM. Furthermore, PFBA up-regulated the proliferation-related factors downstream of ERRγ and inhibited by PI3K/Akt inhibitor LY294002, which also suppressed the cell proliferation induced by PFBA. Taken together, the results revealed that PFBA had estrogen effects at the human-related exposure concentration, and demonstrated a new estrogen effects mechanism of PFBA via ERRγ pathway.