Abstract
The present study aimed to investigate whether VEGF was involved in bisphosphonate (BP)-induced apoptosis and differentiation of osteoblasts. Murine MC3T3-E1 osteoblasts were stimulated with zoledronic acid (ZA) for 7 days. VEGF mRNA and protein expression levels were determined via reverse transcription-quantitative PCR and western blot analysis, respectively. Cell viability was evaluated using Cell Counting Kit-8 assay. In addition, the cell apoptotic rate and the expression levels of apoptosis-related proteins were measured using a TUNEL staining kit and western blot analysis, respectively. To evaluate mineralization, cells were stained with alizarin red, while the secretion levels of alkaline phosphatase (ALP) were measured using the corresponding assay kit. Finally, the expression levels of differentiation-related proteins and proteins of the Nod-like receptor family pyrin domain-containing 3 (NLRP3)/caspase 1/gasdermin D (GSDMD) pyroptosis pathway were measured by western blot analysis. VEGF expression level was notably decreased in ZA-stimulated MC3T3-E1 cells. However, the viability of these cells was enhanced following VEGF addition. Furthermore, VEGF attenuated apoptosis, promoted mineralization and increased ALP activity in ZA-stimulated MC3T3-E1 cells. The ZA-mediated decrease in the protein expression of the osteogenic genes osteopontin, osteocalcin and runt-related transcription factor 2 was restored after MC3T3-E1 cell treatment with 10 ng/ml VEGF. The present study demonstrated that VEGF could attenuate BP-induced apoptosis and differentiation of MC3T3 cells by regulating the NLRP3/caspase 1/GSDMD pathway.