Effects of Liriopis Tuber Water Extract on RANKL-induced Osteoclast Differentiation / 체질인류학회지

ABSTRACT

Increased formation and activation of osteoclast lead to unwanted bone resorption. Several natural products which have inhibitory effects on osteoclast differentiation and function are under investigation to prevent and treat the osteoporotic bone disease. Liriopis tuber has been used in Oriental medicine for the suppression of cough, expectoration, thirst, and has been used for sthenia, diuresis, blood glucose regulation, treatment of xerostomia, and constipation. Also, recently it has been reported that Liriopsis tuber has anti-inflammatory, anti-thrombic, anti-adhesive activities. The purpose of this study was to evaluate the effects of Liriopis tuber on osteoclast differentiation and was to evaluate of its mechanism. Water extract of Liriopis tuber significantly inhibited receptor activator of nuclear factor-kappaB ligand (RANKL)-induced osteoclast differentiation in bone marrow macrophages (BMMs) in a dose dependent manner. However, water extract of Liriopis tuber did not affect cytotoxicity when compared with control. The mRNA expression of c-Fos, NFATc1, tartrate resistant-acid phosphatase (TRAP), and cathepsin K induced by RANKL was inhibited by water extract of Liriopis tuber treatment. Also, water extract of Liriopis tuber inhibited the protein expression of c-Fos and NFATc1 expression in BMMs treated with RANKL. Among the signal pathways, water extract of Liriopis tuber suppressed the phosphorylation of p38 induced by RANKL. In summary, Liriopis tuber exerted inhibitory effects on osteoclast diffentiation via suppression of c-Fos and NFATc1 which are essential gene to osteoclastogenesis. Taken together, these results suggest that Liriopis tuber may be a useful candidate in the treatment of osteoporosis without special toxicity.