Fibroblast growth factor 2 promotes osteo/odontogenic differentiation in stem cells from the apical papilla by inhibiting PI3K/AKT pathway

Abstract Fibroblast growth factor 2 (FGF2) is a crucial factor in odontoblast differentiation and dentin matrix deposition, which facilitates pulpodentin repair and regeneration. Nevertheless, the specific biological function of FGF2 in odontoblastic differentiation remains unclear because it is controlled by complex signalling pathways. This study aimed to investigate the mechanism underlying the effect of FGF2 on osteo/odontogenic differentiation of stem cells from the apical papilla (SCAP). SCAP were pretreated with conditioned media containing FGF2 for 1 week, followed by culturing in induced differentiation medium for another week. RNA sequencing (RNA-seq) combined with quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to evaluate the pathways affected by FGF2 in SCAP. Osteo/odontogenic differentiation of SCAP was determined using Alizarin red S staining, alkaline phosphatase staining, RT-qPCR, and western blotting. Pretreatment with FGF2 for 1 week increased the osteo/odontogenic differentiation ability of SCAP. RNA-seq and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed that phosphatidylinositol 3-kinase (PI3K)/AKT signalling is involved in the osteogenic function of FGF2. RT-qPCR results indicated that SCAP expressed FGF receptors, and western blotting showed that p-AKT was reduced in FGF2-pretreated SCAP. The activation of the PI3K/AKT pathway partially reversed the stimulatory effect of FGF2 on osteo/odontogenic differentiation of SCAP. Our findings suggest that pretreatment with FGF2 enhances the osteo/odontogenic differentiation ability of SCAP by inhibiting the PI3K/AKT pathway.