MicroRNA-15b-5p Modulates the Differentiation of Human Dental Pulp Stem Cells into Odontoblasts via Targeting IGF1

Objectives: The purpose of this study is to unveil the modulatory effect of microRNA (miRNA)-15b-5p on the differentiation of dental pulp stem cells (hDPSCs).Methods: Following the differentiation of hDPSCs into odontoblasts, qRT-PCR (quantitative reverse transcription-polymerase chain reaction) was used to determine miR-15b-5p expression in the cells. Dual-luciferase reporter (DLR) assay was adopted to confirm the downstream target gene of miR-15b-5p. Post transfection of miR-15b-5p mimic, inhibitor or si-insulin-like growth factor 1 (IGF1) into the differentiated cells, alkaline phosphatase (ALP) activity and mineralized nodule formation were eval-uated by a commercial assay kit and alizarin red staining. Differentiation-related protein levels were evaluated using Western blotting. Transwell and extracellular matrix adhesion cell assays were performed to observe the invasion and adhesion of differ-entiated cells.Results: Downregulation of miR-15b-5p was observed in odontoblasts. MiR-15b-5p targeted IGF1, and miR-15b-5p mimic repressed IGF1 expression. Additionally, miR-15b-5p inhibitor strengthened the ALP activity and mineralized nodule forma-tion, enhanced the invasion and adhesion of hDPSCs, and promoted the expression levels of dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), osteopontin (OPN), bone sialoprotein (BSP) and osteocalcin (OCN) during the differentiation of hDPSCs. However, the miR-15b-5p mimic exerted the effects opposite to the miR-15b-5p inhibitor. Besides, silencing of IGF1 reversed the effects of miR-15b-5p inhibitor on the above indexes.Conclusions: MiR-15b-5p regulates the differentiation of hDPSCs into odontoblasts by targeting IGF1.