The effect of insulin-like growth factor-I on production of vascular endothelial growth factor by amnion-derived (WISH) cells

Abstract

Objective. Our objective was to clarify the modulation of vascular endothelial growth factor (VEGF) by amniotic cells. Design. Amnion-derived (WISH) cells were cultured, and the effect of insulin-like growth factor (IGF), mitogen-activated protein (MAP) kinase kinase and/or extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitors (U0126), and phosphatidylinositol (PI) 3-kinase inhibitors (wortmannin) on the production of VEGF was examined. VEGF was assayed using ELISA. The activations of MAP kinase and akt, which is phosphorylated by PI 3-kinase, were detected by Western blot analysis using anti-phosphorylated MAP kinase antibody and anti-phosphorylated akt antibody. Results. In the time course of VEGF production following IGF-I treatment, VEGF production showed significant increases only at 16 and 32 h ( p<0.01). Also, IGF-I increased the production of VEGF by WISH cells in a dose-dependent manner. The MAP kinase and akt activities were recognized by treatment with IGF-I and suppressed by U0126 and wortmannin, respectively. When WISH cells were pretreated for 2 h with U0126 and wortmannin and then treated with IGF-I for 16 h, the production of VEGF was significantly decreased in a dose-dependent manner ( p<0.01, p<0.01, respectively). Conclusions. WISH cells appeared to produce VEGF via a mechanism involving tyrosine kinase interaction with IGF-I receptor, resulting in MAP kinase and PI 3-kinase activation. It is suggested that VEGF may contribute to the neovascularization and proliferation of the placenta and gestational tissue, and IGF-I may play an important role in the modulation of VEGF production in the placenta.