Neotuberostemonine inhibits osteoclastogenesis via blockade of NF-κB pathway

Osteoporosis has been attributed to low bone mass arising from cellular communications between bone formation and bone resorption. Osteoclastogenesis is induced by M-CSF and RANKL in hematopoietic lineage cells. Once RANK/RANKL complex is formed, TRAF6 is recruited and triggers the activation of NF-κB pathway and the expression of osteoclast-related genes including NFATc1. Neotuberostemonine (NTS) is an active compound isolated from Stemona tuberosa Lour. Pharmacologically, NTS has been known to possess antitussive, anti-fibrotic and anti-inflammatory activities through regulation of macrophage. However, the influence of NTS to osteoclastogenesis has not been reported. The purpose of this study is to investigate whether NTS can modulate the osteoclastogenesis induced by RANKL or cancer cells. We found that NTS inhibits RANKL- or cancer cell-mediated osteoclastogenesis via blockade of TRAF6 and NF-κB activation. NTS also impairs the formation of F-actin ring structure, an important feature of osteoclast differentiation and function. These results indicate that NTS can be a preventive and therapeutic candidate for bone-related disease and that NTS provides insights underlying molecular mechanisms that influence osteoclastogenesis.