Effects and mechanisms of pesticide carbendazim on osteogenic differentiation

BackgroundCarbendazim (CBZ), a widely used benzimidazole fungicide, has raised increasing concerns regarding the health risks associated with its residues. However, the toxic effects and associated mechanisms of CBZ on the skeletal system have not been reported.ObjectiveTo elucidate the effects of carbendazim on osteogenic differentiation and its underlying mechanisms.MethodsMC3T3-E1 mouse pre-osteoblastic cells were treated with 1, 10, and 100 μmol·L−1 CBZ for 24 h to examine cell viability, alkaline phosphatase (ALP) activity, bone nodule formation, reactive oxygen species (ROS) level, malondialdehyde (MDA) content, and nitric oxide synthase (NOS) activity. Transcriptomics was used to identify differentially expressed genes (DEGs) in osteoblasts exposed to CBZ. Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis (GSEA) were employed to analyze the potential biological pathways of DEGs. Real-time polymerase chain reaction (RT-PCR) and Western blot were used to validate changes in gene and protein expression.ResultsExposure to 10 and 100 μmol·L−1 CBZ significantly reduced osteoblast viability, ALP activity, bone nodule formation, and NOS activity, while increasing intracellular ROS levels. CBZ at 100 μmol·L−1 concentration significantly elevated MDA level (P < 0.05). The transcriptomic analysis revealed that 1 μmol·L−1 CBZ treatment resulted in 385 significantly DEGs. The KEGG enrichment analysis revealed that CBZ significantly affects hormone regulation pathways (including parathyroid hormone, growth hormone, dopamine, and oxytocin), mitogen-activated protein kinase (MAPK) and cyclic GMP-dependent protein kinase G (cGMP-PKG) signaling pathways, focal adhesion and adherens junction, as well as the NOD-like receptor signaling pathway and the mRNA surveillance (NMD) pathway. The results of GSEA showed that CBZ significantly inhibited the bile acid metabolism and the Wnt/β-catenin pathway in osteoblasts. The validation results demonstrated that CBZ significantly suppressed the mRNA expression of Wnt3a and β-catenin, as well as the protein expression of Runx2 and Osterix in the Wnt/β-catenin pathway.ConclusionCBZ exposure exhibits potential skeletal toxicity, and its mechanism is through promoting oxidative stress, interfering with the Wnt/β-catenin pathway in osteogenic differentiation, thereby inhibiting the bone formation function of osteoblasts.