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

Abstract

Abstract. 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 RANKLmediated ROS production by Nrf2-mediated up-regulation of phase II antioxidant enzymes.

Genistein Inhibits Osteoclastic Differentiation of RAW 264.7 Cells via Regulation of ROS Production and Scavenging

“…Previous studies have reported that the intracellular ROS level increases during RANKL-induced osteoclast differentiation, and this ROS generation can be attenuated by several antioxidants, including curcumin and fisetin [29,30]. Our previous study also showed that the intracellular ROS level in RANKL-stimulated Raw 264.7 cells increased to its largest value within two days and then declined [28].…”

“…Treatment with genistein reduced the number of multinucleated TRAP-positive cells and TRAP activity in a dose-dependent manner (Figure 2B,C). The inhibitory effects of natural flavonoids, such as luteolin [24], baicalein [25], resveratrol [26], epigallocatechin-3-gallate [27], scopoletin [28], curcumin [29] and fisetin [30], as potent antioxidants on osteoclast differentiation from osteoclastic precursors through controlling ROS generation, have also been reported. The suppressive effect on osteoclastogenesis via attenuating ROS production in RANKL-treated RAW 264.7 cells was observed in luteolin, which showed potent cellular antioxidant activity in rat C6 astroglioma cells [22,24].…”

“…Scopoletin at 1–10 µM also alleviated general ROS and superoxide anions produced in RANKL-treated RAW 264.7 cells to inhibit osteoclastic differentiation [28]. In addition, fisetin inhibited osteoclastogenesis through the prevention of RANKL-induced ROS production by nuclear transcription factor-erythroid 2-related factor 2 (Nrf2)-mediated upregulation of phase II antioxidant enzymes [30]. Thus, this study’s data support the hypothesis that the suppressive effect of genistein on RANKL-induced osteoclast differentiation may be closely related with its intracellular antioxidant activity.…”

Rab27A Regulates Transport of Cell Surface Receptors Modulating Multinucleation and Lysosome-Related Organelles in Osteoclasts

“…siRNA experiments in OCLs were performed as described previously48. The target sequence of murine Rab27A siRNA was: GGACUUAAUCAUCTAAGAGAAUGGAA (Rab27A siRNA).…”

Isolation of Fisetin from Elaeagnus indica Serv. Bull. (Elaeagnaceae) with antioxidant and antiproliferative activity

“…Recently, several researchers worked on the antioxidant potential of fisetin by performing various tests. [18][19][20] Wherein Phenolic hydroxyl groups are prone to donate a hydrogen atom to free radicals and extend conjugated aromatic system to delocalize an unpaired electron. 21 DPPH radical scavenging activity guided isolation of acetone extract of E. indica yielded a flavonol compound, i.e.…”