Nongenomic effects and mechanistic study of butyl benzyl phthalate-induced thyroid disruption: Based on integrated in vitro, in silico assays and proteome analysis.

Based on in vitro and in silico assays as well as proteome analysis, this study explored the nongenomic mechanism for butyl benzyl phthalate (BBP)-induced thyroid disruption. Molecular docking simulations showed that BBP could dock into the Arg-Gly-Asp (RGD) domain of integrin αvβ3 and form hydrogen bonds with a docking energy of -35.80 kcal/mol. This chemical enhanced rat pituitary tumor cell (GH3) proliferation and exhibited thyroid hormone-disrupting effects at 5-10 μmol/L. Meanwhile, BBP upregulated β3 gene expression and activated the downstream mitogen-activated protein kinase (MAPK) pathway in GH3 cells. Interestingly, GH3 cell proliferation was attenuated by integrin αvβ3 inhibitor (RGD peptide) or ERK1/2 inhibitor (PD98059), suggesting that the disruptions might be partly attributed to its interaction with integrin αvβ3 and activation of MAPK. Furthermore, quantitative proteomic analysis of zebrafish embryos exposed to BBP at an environmentally relevant concentration of 0.3 μmol/L revealed that BBP perturbed proteins and pathways related to cell communication (e.g., integrin binding) and signal transduction (e.g., MAPK signaling pathway). Taken together, our results supported that the biological effects of BBP-activated integrin αvβ3 mediated by the nongenomic pathway play an important role in its thyroid disruption. CAPSULE: The nongenomic pathway plays a vital role in the thyroid disruption-inducing actions of BBP.