Inhibition of Osteoclastogenesis and Bone Resorption in vitro and in vivo by a prenylflavonoid xanthohumol from hops

Jing Li,Juan Xie,Xueyun Ma,Zhiying Yue,Jian Luo,Mingyao Liu,Chunbing Zheng,Xiushan Wu,Li Zeng,Huayun Deng

doi:10.1038/srep17605

Abstract

Excessive RANKL signaling leads to superfluous osteoclast formation and bone resorption, is widespread in the pathologic bone loss and destruction. Therefore, targeting RANKL or its signaling pathway has been a promising and successful strategy for this osteoclast-related diseases. In this study, we examined the effects of xanthohumol (XN), an abundant prenylflavonoid from hops plant, on osteoclastogenesis, osteoclast resorption, and RANKL-induced signaling pathway using both in vitro and in vivo assay systems. In mouse and human, XN inhibited osteoclast differentiation and osteoclast formation at the early stage. Furthermore, XN inhibited osteoclast actin-ring formation and bone resorption in a dose-dependent manner. In ovariectomized-induced bone loss mouse model and RANKL-injection-induced bone resorption model, we found that administration of XN markedly inhibited bone loss and resorption by suppressing osteoclast activity. At the molecular level, XN disrupted the association of RANK and TRAF6, resulted in the inhibition of NF-κB and Ca2+/NFATc1 signaling pathway during osteoclastogenesis. As a results, XN suppressed the expression of osteoclastogenesis-related marker genes, including CtsK, Nfatc1, Trap, Ctr. Therefore, our data demonstrated that XN inhibits osteoclastogenesis and bone resorption through RANK/TRAF6 signaling pathways. XN could be a promising drug candidate in the treatment of osteoclast-related diseases such as postmenopausal osteoporosis.

Highlights

Osteoclast are the only cells for bone-resorbing in mammals[1]
In order to determine the effect of XN on osteoclastogenesis, we employed three standard in vitro osteoclast differentiation models, mouse BMMs with RANKL and macrophage-colony stimulating factor (M-CSF) stimulation model, RAW264.7 cells with RANKL stimulation model, and human peripheral blood mononuclear cells (PBMCs) cells with RANKL and M-CSF stimulation model
Our results demonstrate that XN inhibited osteoclastogenesis maximally when added from the beginning with RANKL stimulation (Fig. 1D)

Summary

Introduction

Osteoclast are the only cells for bone-resorbing in mammals[1]. Many pathological bone diseases, including postmenopausal osteoporosis, periodontitis, rheumatoid arthritis, lytic bone metastasis, and Paget’s disease, are characterized by progressive and excessive bone resorption[2]. A number of osteoclast-related marker gene, including tartrateresistant acid phosphatase (Trap), calcitonin receptor (Ctr), cathepsin K (Ctsk), and nuclear factor of activated T cells (Nfatc1), are upregulated. XN is the most abundant prenylflavonoid from hops plant, with a content of 0.1–1% (dry weight)[11] This compound has attracted much interest due to its proven pharmacologic safety[12] and its multiple bioactivities, including anti-cancer[13], anti-diabetes[14], anti-inflammatory[11], anti-bacteria and parasite[11], and hepatic protection[11]. In the present study, using multiple in vitro osteoclast differentiation and bone resorption approaches, we demonstrated that XN suppressed RANKL-induced osteoclast formation and function within non-growth inhibitory concentrations. Our data demonstrate that XN suppresses osteoclastogenesis and osteoporosis in vitro and in vivo through RANK/TRAF6 signaling pathways

Methods

Results

Conclusion