Stem Cell Factor induces cell migration through PI3K and MEK/ERK

Objectives: Stem cell factor (SCF) is considered a crucial cytokine in the regulation of a variety of cell functions, such as proliferation, differentiation, survival, and migration.  In this study, we sought to determine the effects and molecular mechanisms of SCF on the migration of dental pulp cells (hDPs). Methods: For this study, human dental pulp cells were isolated and characterized. Chemotaxis assays were performed in order to investigate the migratory response of hDPs in the presence of 0, 20, 50, 100, 150, and 200ng/ml SCF.  PI3K and MEK/ERK pathway inhibitors LY294002 (20µM for 1 hour) and UO126 (20µM for 1 hour) were used to detect the activation of phospho-AKT and phospho-ERK after SCF stimulation (100ng/ml) by western blotting.  In addition, RhoA expression levels and cytoskeletal changes in response to SCF were identified by immunoblotting and rhodamine-phalloidin staining, respectively.  Results: Application of SCF at increasing levels resulted in increased percent numbers of migratory cells from 143.85±52.27% at 20ng/ml to 265.22±66.37% at 150ng/ml compared to control (P<0.05).  SCF induced phosphorylation of both ERK1/2 and AKT as evidenced by western blot. There was a peak in the ERK1/2 and AKT phosphorylation response after 5 minutes and 3 minutes, respectively; and highest levels of phosphorylation were achieved after application of 100-150ng/ml SCF.  Inhibition of PI3K and MEK/ERK activity by LY294002 and UO126 was paralleled by a marked reduction of migration (P<0.05) and RhoA expression in the presence or absence of SCF compared to the SCF treated groups. In addition, application of SCF at a concentration of 100ng/ml for 4 hours resulted in cytoskeletal rearrangement and depolarization of hDPs.  Conclusion: These studies suggest that SCF promotes hDP migration and rapid PI3K and MAPK/ERK pathway activation in a dose-dependent manner. Funding by NIDCR grant DE019463 to XL is gratefully acknowledged.