Enhancement of basic fibroblast growth factor-stimulated VEGF synthesis by Wnt3a in osteoblasts

It is currently recognized that the Wnt signaling pathway regulates bone mass. We have previously reported that the basic fibroblast growth factor (FGF-2) stimulates the synthesis of the vascular endothelial growth factor (VEGF) at least in part via the p44/p42 mitogen-activated protein (MAP) kinase and the stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK) in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of Wnt3a on FGF-2-stimulated VEGF synthesis in MC3T3-E1 cells. Wnt3a significantly augmented the FGF-2-stimulated VEGF release in a dose-dependent manner in the range between 1 and 30 ng/ml. Lithium chloride and SB216763, inhibitors of glycogen synthase kinase 3β (GSK3β), enhanced the FGF-2-stimulated VEGF release. Wnt3a did not affect the phosphorylation of the p44/p42 MAP kinase, SAPK/JNK, Akt, p38 MAP kinase or the p70 S6 kinase induced by FGF-2. Wnt3a and SB216763 increased the levels of VEGF mRNA expression induced by FGF-2. These results strongly suggest that Wnt3a enhances VEGF synthesis stimulated by FGF-2 via activation of the canonical Wnt/β-catenin pathway in osteoblasts.