[Insulin-like growth factor 1 regulates expression of stem cell factor through ERKMAPK signaling pathway in gastric...

To explore the effect and the intracellular signal transduction pathway of insulin-like growth factor 1 (IGF-1) on the expression of stem cell factor (SCF) in gastric smooth muscle cells (SMC).

Gastric SMC from SD rats were cultured by enzymolysis and identified by α-actin immunofluorescence methods. Western blot and quantitative reverse transcription-polymerase chain reaction were used to examine the expression of SCF in gastric SMC:(1) The level of SCF after gastric SMC were cultured with IGF-1. (2) The level of SCF after IGF-1 receptor (IGF-1Rα) monoclonal antibody were added. (3) Another SMC were pretreated with specific mitogen-activated protein kinase (MEK) inhibitor PD-98059 and phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor LY-294002, and investigate expression of SCF in gastric SMC.

A very low level of SCF was expressed in gastric SMC cultured in bovine serum free medium. A low concentration of IGF-1 (5 and 10 µg/L) had no effect on the expression of SCF (both P>0.05), but the expressions of SCF mRNA and protein increased in IGF-1 at a higher concentration (50, 100 and 150 µg/L) (2.79, 5.51 and 5.35-fold in protein respectively, 1.81, 2.54 and 2.38-fold in mRNA respectively, all P<0.05), and IGF-1 in 100 µg/L may be the effective final concentration (all P<0.05). The peak of SCF increment was at the 16th hour with IGF-1 (2.36-fold in protein, 5.51-fold in mRNA, all P<0.05). The expression of SCF could be inhibited by IGF-1 receptor monoclonal antibody in a dose-dependent manner (all P<0.05). The IGF-1-induced SCF expression was reduced significantly by a pretreatment of PD-98059 (23% in protein and 48% in mRNA, P<0.05). And LY-294002 had no effect on the expression of SCF (P>0.05).

The SCF expression in gastric SMC is stimulated by IGF-1 in both dose- and time-dependent manners through IGF-1R in which ERKMAPK signal transduction may play an important role.