Benzotriazole ultraviolet stabilizers impair trophoblast function at nanomolar concentrations via GPER signaling: implications for placental health.

Benzotriazole ultraviolet stabilizers (BUVSs) are ubiquitous emerging contaminants with documented multifaceted toxicity. However, their potential impacts on human placental development and underlying mechanisms remain poorly understood. This study investigated the effects of three representative BUVSs (UV-P, UV-326, and UV-328) on trophoblast function via G-protein-coupled estrogen receptor (GPER) pathway. Molecular dynamics simulations revealed that UV-328 binds to GPER with higher affinity than UV-P and UV-326, which even exceeds that of the native ligand 17β-estradiol (E2). Calcium influx assays demonstrated that all three BUVSs activated GPER signaling pathway in a concentration-dependent manner, with lowest observed effect concentrations (LOECs) of 10-100 nM. Each BUVS enhanced trophoblast proliferation-most potently by UV-328 (LOEC = 1 nM)-through GPER-mediated upregulation of Cyclin D1 and Ki-67, indicating promotion of cell cycle progression. Wound-healing and transwell assays showed that all three BUVSs promoted trophoblast migration and invasion with LOECs of 1-100 nM via GPER pathway. Furthermore, the three BUVSs opposing regulated expression between epithelial (down) and mesenchymal (up) markers and upregulated the expression of matrix metalloproteinases (MMP2/9) through activating GPER, indicating that GPER-mediated epithelial-mesenchymal transition and extracellular matrix remodeling should be key events in BUVSs-induced migration and invasion. UV-328 consistently exhibited the strongest effects on trophoblast functions, aligning with its superior GPER activation potency. Importantly, the LOECs for UV-328-induced trophoblast dysfunction fall within nanomolar ranges relevant to estimated human exposure levels. Together, these results reveal GPER-mediated mechanistic pathways through which BUVSs disrupt trophoblast function and highlight their potential risk in gestational disorders.