Fisetin Inhibits Osteoclastogenesis Through Prevention of RANKL-Induced ROS Production by Nrf2-Mediated Up-regulation of Phase II Antioxidant Enzymes

• Published in: Journal of Pharmacological Sciences Vol. 121; no. 4; pp. 288 - 298
• Main Authors: Sakai, Eiko, Shimada-Sugawara, Megumi, Yamaguchi, Yu, Sakamoto, Hiroshi, Fumimoto, Reiko, Fukuma, Yutaka, Nishishita, Kazuhisa, Okamoto, Kuniaki, Tsukuba, Takayuki
• Format: Journal Article
• Language: English
• Published: Japan Elsevier B.V 2013; The Japanese Pharmacological Society; Elsevier
• Subjects: Animals; Bone Resorption - prevention & control; Cell Differentiation - drug effects; Cell Differentiation - genetics; Dose-Response Relationship, Drug; fisetin; Flavonoids - pharmacology; Gene Expression Regulation, Developmental - drug effects; Heme Oxygenase-1 - metabolism; Heme Oxygenase-1 - physiology; Macrophage Colony-Stimulating Factor - physiology; Macrophages - cytology; Male; Mice; Mice, Inbred BALB C; NF-E2-Related Factor 2 - metabolism; NF-E2–related factor 2 (Nrf2); NFATC Transcription Factors - metabolism; nuclear factor of activated T cells cytoplasmic-1 (NFATc1); osteoclast; Osteoclasts - cytology; Osteoclasts - physiology; reactive oxygen species (ROS); Reactive Oxygen Species - metabolism; Receptor Activator of Nuclear Factor-kappa B - antagonists & inhibitors; Receptor Activator of Nuclear Factor-kappa B - physiology; Up-Regulation; fisetin; reactive oxygen species (ROS); osteoclast; NF-E2–related factor 2 (Nrf2); nuclear factor of activated T cells cytoplasmic-1 (NFATc1)
• ISSN: 1347-8613; 1347-8648
• DOI: 10.1254/jphs.12243FP

Osteoclasts (OCLs) are multinucleated bone-resorbing cells that are differentiated by stimulation with receptor activator of nuclear factor kappa-B ligand (RANKL) and macrophage colony-stimulating factor. We recently demonstrated that regulation of heme-oxygenase 1 (HO-1), a stress-induced cytoprotective enzyme, also functions in OCL differentiation. In this study, we investigated effects of fisetin, a natural bioactive flavonoid that has been reported to induce HO-1 expression, on the differentiation of macrophages into OCLs. Fisetin inhibited the formation of OCLs in a dose-dependent manner and suppressed the bone-resorbing activity of OCLs. Moreover, fisetin-treated OCLs showed markedly decreased phosphorylation of extracellular signal-regulated kinase, Akt, and Jun N-terminal kinase, but fisetin did not inhibit p38 phosphorylation. Fisetin up-regulated mRNA expression of phase II antioxidant enzymes including HO-1 and interfered with RANKL-mediated reactive oxygen species (ROS) production. Studies with RNA interference showed that suppression of NF-E2–related factor 2 (Nrf2), a key transcription factor for phase II antioxidant enzymes, rescued fisetin-mediated inhibition of OCL differentiation. Furthermore, fisetin significantly decreased RANKL-induced nuclear translocation of cFos and nuclear factor of activated T cells cytoplasmic-1 (NFATc1), which is a transcription factor critical for osteoclastogenic gene regulation. Therefore, fisetin inhibits OCL differentiation through blocking RANKL-mediated ROS production by Nrf2-mediated up-regulation of phase II antioxidant enzymes.