Effect of Basic Fibroblast Growth Factor on Expression of Let-7 MicroRNA in Proliferation of Human Dental Pulp Cells

Abstract

Objective: Basic fibroblast growth factor (bFGF) plays a pivotal role in cell proliferation, differentiation and extracellular matrix turnover in various tissues. In human dental pulp cells (HDPCs), let-7 microRNA is involved in cell proliferation and differentiation. There is little information on the effect of bFGF-induced cell proliferation on let-7 microRNA in HDPCs. This study investigated the effect of bFGF on let-7g, let-7f, and let-7i microRNAs and some of the genes involved in cell proliferation including p53 and Ki67 in HDPCs.Material and Methods: HDPCs were cultured and treated with bFGF at 0, 1, and 5 ng/mL. Cell proliferation was examined using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay at 24 and 48 hours. Additionally, gene expressions of let-7g, let-7f, let-7i microRNAs, and p53 and Ki67 were examined by quantitative real-time polymerase chain reaction at 24 hours. All experiments were performed in triplicate.Results: The results showed that let-7g, let-7f, and let-7i microRNAs were expressed in HDPCs. MTT assays showed that bFGF induced greater cell proliferation than the controls at 24 and 48 hours (p-value<0.050). HDPCs treated with bFGF showed a decrease in p53 expression (p-value<0.001) while Ki67 expression increased (p-value<0.001). The expression of let-7g microRNA decreased under the influence of bFGF (p-value<0.050). However, bFGF had no effect on expression of let-7f and let-7i microRNAs (p-value>0.050).Conclusion: Our preliminary study showed that exogenous bFGF could decrease let-7g microRNA expression suggesting that let-7g microRNA may be involved in bFGF-induced HDPCs proliferation.