Objective To explore the role of flurochloridone (FLC) on osteogenic differentiation and the potential mechanism of inhibiting bone formation, and to provide new insights into bone health risks associated with FLC pesticide exposure.

Methods Neonatal rat skull differentiation primary osteoblast model was used to investigate the effects of 1, 10 and 100 μmol·L^-1 FLC exposure on cell viability, osteogenic differentiation alkaline phosphatase (ALP) activity, and bone mineralization nodule formation, respectively. The potential mechanism underlying the inhibition of FLC on osteoblast differentiation was analyzed using osteogenic differentiation gene chip technique, and the expression of key genes and proteins in the pathway was validated using reverse transcription polymerase chain reaction (RT-PCR) and protein immunoblotting (Western blot) methods.

Results Exposure to FLC at a concentration of 100 μmol·L⁻¹ reduced cell proliferation, ALP activity, and the formation of mineralized nodules in primary osteoblasts. Gene chip analyses revealed that exposure to 10 μmol·L⁻¹ FLC induced 15 differentially expressed genes (DEGs). Among these, MMP9 and Tnf were up-regulated, while Nkx3⁃2, Tuft1, Bmp2, Col12a1, Pparg, Enam, Igf1, Bmp5, Bmp3, Calcr, Egf, Igfbp3, and Col14a1 were down-regulated. Results of protein-protein interaction analyses and gene ontology enrichment analyses indicated that FLC inhibited the BMP/SMAD pathway involved in osteogenic differentiation. FLC suppressed the protein expression of BMP2 and Osterix, as well as the expression of key genes critical for osteogenic differentiation and ossification, such as BMP2, Runx2, SMAD1, and SMAD5 in the BMP/SMAD pathway.

Conclusion FLC affects osteogenic differentiation and bone formation potential by regulating the BMP/SMAD axis and the expression of osteogenic genes, suggesting its potential risk in bone metabolism.