(-)-Epigallocatechin gallate inhibits basic fibroblast growth factor-stimulated interleukin-6 synthesis in osteoblasts

• Published in: Hormone and metabolic research Vol. 40; no. 10; p. 674
• Main Authors: Tokuda, H, Takai, S, Hanai, Y, Matsushima-Nishiwaki, R, Yamauchi, J, Harada, A, Hosoi, T, Ohta, T, Kozawa, O
• Format: Journal Article
• Language: English
• Published: Germany 01.10.2008
• Subjects: Animals; Anthracenes - pharmacology; Catechin - analogs & derivatives; Catechin - pharmacology; Cells, Cultured; Fibroblast Growth Factor 2 - pharmacology; Interleukin-6 - biosynthesis; Mice; Mitogen-Activated Protein Kinase 3 - metabolism; Organic Chemicals - pharmacology; Osteoblasts - drug effects; Osteoblasts - enzymology; Osteoblasts - metabolism; p38 Mitogen-Activated Protein Kinases - metabolism; Phosphorylation - drug effects
• ISSN: 0018-5043
• DOI: 10.1055/s-2008-1073164

We previously showed that basic fibroblast growth factor (FGF-2) activates the mitogen-activated protein (MAP) kinase superfamily in osteoblast-like MC3T3-E1 cells and that p38 MAP kinase functions as a positive regulator in the FGF-2-stimulated synthesis of interleukin-6 (IL-6), a potent bone-resorptive agent, in these cells. In the present study, we investigated the exact mechanism of IL-6 and the effects of (-)-epi-gallocatechin gallate (EGCG), one of the major green tea flavonoids, on the synthesis of IL-6. PD98059, an inhibitor of MEK, but not SP600125, an inhibitor of stress-activated protein kinase/c-Jun N-terminal kinase, suppressed FGF-2-stimulated IL-6 synthesis. EGCG significantly reduced the IL-6 synthesis stimulated by FGF-2 in a dose-dependent manner. EGCG attenuated the FGF-2-induced phosphorylation of p44/p42 MAP kinase and p38 MAP kinase. These results strongly suggest that EGCG inhibits the FGF-2-stimulated synthesis of IL-6 at least partly via suppression of the p44/p42 MAP kinase pathway and the p38 MAP kinase pathway in osteoblasts.