Incadronate Amplifies Prostaglandin F2α-induced Vascular Endothelial Growth Factor Synthesis in Osteoblasts

• Published in: The Journal of biological chemistry Vol. 278; no. 21; p. 18930
• Main Authors: Haruhiko Tokuda, Atsushi Harada, Kouseki Hirade, Hiroyuki Matsuno, Hidenori Ito, Kanefusa Kato, Yutaka Oiso, Osamu Kozawa
• Format: Journal Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology 23.05.2003
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M209159200

We have previously reported that prostaglandin F 2 α (PGF 2 α ) activates p44/p42 mitogen-activated protein kinase (MAPK) through protein kinase C (PKC) in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the mechanism of vascular endothelial growth factor (VEGF) synthesis induced by PGF 2 α and the effect of incadronate on the VEGF synthesis in these cells. PGF 2 α significantly stimulated the VEGF synthesis in a dose-dependent manner between 1 p m and 10 μ m . Cycloheximide reduced the PGF 2 α effect. PGF 2 α increased the levels of mRNA for VEGF. Cloprostenol, a PGF 2 α -sensitive receptor agonist, potently induced the VEGF synthesis. Indomethacin, an inhibitor of cyclooxygenase, significantly reduced the PGF 2 α -induced VEGF synthesis. Bisindolylmaleimide, an inhibitor of PKC, reduced the PGF 2 α -induced VEGF synthesis. The VEGF synthesis induced by PGF 2 α was significantly attenuated in the PKC down-regulated cells. PGF 2 α elicited the translocation of PKCβI from cytosol to membrane fraction. PD98059 or U0126, inhibitors of MEK, suppressed the VEGF synthesis induced by PGF 2 α . Farnesyltransferase inhibitor failed to affect the PGF 2 α -induced VEGF synthesis. Incadronate enhanced the synthesis of VEGF induced by PGF 2 α . NaF-induced VEGF synthesis was also amplified by incadronate. PD98059 suppressed the enhancement by incadronate of PGF 2 α -induced VEGF synthesis. Incadronate markedly enhanced the phosphorylation of Raf-1, MEK1/2, and p44/p42 MAPK induced by PGF 2 α or 12- O -tetradecanoylphorbol-13-acetate, a PKC activator. Incadronate significantly enhanced the cloprostenol-increased level of VEGF concentration in mouse plasma in vivo . These results strongly suggest that PGF 2 α stimulates VEGF synthesis through the PKC-dependent activation of p44/p42 MAPK in osteoblasts and that the incadronate enhances the VEGF synthesis at the point between PKC and Raf-1.