Basic Fibroblast Growth Factor Regulates Gene and Protein Expression Related to Proliferation, Differentiation, and Matrix Production of Human Dental Pulp Cells

Abstract

Introduction: Basic fibroblast growth factor (bFGF) plays differential effects on the proliferation, differentiation, and extracellular matrix turnover in various tissues. However, limited information is known about the effect of bFGF on dental pulp cells. The purposes of this study were to investigate whether bFGF influences the cell differentiation and extracellular matrix turnover of human dental pulp cells (HDPCs) and the related gene and protein expression as well as the role of the mitogen-activated protein kinase (MEK)/extracellular-signal regulated kinase (ERK) signaling pathway. The expression of fibroblast growth factor receptors (FGFRs) in HDPCs was also studied.

Methods: The expression of FGFR1 and FGFR2 in HDPCs was investigated by reverse-transcription polymerase chain reaction. HDPCs were treated with different concentrations of bFGF. Cell proliferation was evaluated using the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Cell differentiation was evaluated using alkaline phosphatase (ALP) staining. Changes in messenger expression of cyclin B1 and tissue inhibitor of metalloproteinase (TIMP) 1 were determined by reverse-transcription polymerase chain reaction. Changes in protein expression of cdc2, TIMP-1, TIMP-2, and collagen I were determined by Western blotting. U0126 was used to clarify the role of MEK/ERK signaling.

Results: HDPCs expressed both FGFR1 and FGFR2. Cell viability was stimulated by 50-250 ng/mL bFGF. The expression and enzyme activities of ALP were inhibited by 10-500 ng/mL bFGF. At similar concentrations, bFGF stimulates cdc2, cyclin B1, and TIMP-1 messenger RNA and protein expression. bFGF showed little effect on TIMP-2 and partly inhibited collagen I expression of pulp cells. U0126 (a MEK/ERK inhibitor) attenuated the bFGF-induced increase of cyclin B1, cdc2, and TIMP-1.

Conclusions: bFGF may be involved in pulpal repair and regeneration by activation of FGFRs to regulate cell growth; stimulate cdc2, cyclin B1, and TIMP-1 expression; and inhibit ALP. These events are partly associated with MEK/ERK signaling.

Keywords: Alkaline phosphatase; basic fibroblast growth factor; cell proliferation; dental pulp cells; proliferation; signal transduction; tissue inhibitor of metalloproteinase 1.