Kirenol stimulates osteoblast differentiation through activation of the BMP and Wnt/β-catenin signaling pathways in MC3T3-E1 cells

Kirenol has been reported to possess anti-oxidant, anti-inflammatory, anti-allergic, anti-adipogenic, and anti-arthritic activities; however, its effect on osteoblast differentiation has not yet been reported. The aim of the present study was to evaluate the effect of kirenol on osteoblast differentiation through activation of the bone morphogenetic protein (BMP) and Wnt/β-catenin signaling pathways in MC3T3-E1 cells. Kirenol markedly promoted alkaline phosphatase (ALP) activity and mineralization. Kirenol not only increased the expression of osteoblast differentiation markers, such as ALP, type I collagen (ColA1), and osteopontin (OPN), but also increased the expression of osteoprotegerin/receptor activator of nuclear factor kappa B ligand (OPG/RANKL) ratio. The effects of kirenol on osteoblast differentiation were accompanied by stimulating the expression of the BMP and Wnt/β-catenin signaling pathways, including BMP2, runt-related transcription factor 2 (Runx2), osterix (Osx), low density lipoprotein receptor related protein 5 (LRP5), disheveled 2 (DVL2), β-catenin, cyclin D1 (CCND1), and phosphorylated glycogen synthase kinase 3β (GSK3β). In addition, kirenol up-regulated the expression of β-catenin, CCND1, ALP, and ColA1 which were down-regulated by siRNA knockdown of β-catenin. Overall, these results demonstrate that kirenol is capable of promoting osteoblast differentiation in MC3T3-E1 cells through activation of the BMP and Wnt/β-catenin signaling pathways, suggesting that it is a potential candidate target for treating or preventing osteoporosis.