Leonurine hydrochloride promotes osteogenic differentiation and increases osteoblastic bone formation in ovariectomized mice by Wnt/ß-catenin pathway.

Leonurine hydrochloride (LH) is a synthetic chemical compound derived from leonurine that can be extracted from Leonurus sibiricus and possesses antioxidant, anti-apoptosis, and neuroprotective activities. In previous studies, LH has been demonstrated to attenuate osteoclast activity and prevent bone loss. However, it is unknown whether LH accelerates bone formation and promotes osteogenic differentiation. We systematically examined the effects of LH on ovariectomized-induced osteoporotic mice and the MC3T3-E1 osteoblastic cell line. The results revealed that LH enhanced differentiation of MC3T3-E1 cells, with a dose-dependent increase in alkaline phosphatase (ALP) activity. Moreover, LH upregulated osteogenesis-related gene expression, including osterix, alpha 1 type 1 collagen, runt-related transcription factor 2 (Runx2) and ALP, as shown by quantitative reverse transcription-polymerase chain reaction analysis. At the same time, elevated expression of low-density lipoprotein receptor-related protein 5 and ß-catenin mRNA was detected in the Wnt/ß-catenin pathway. A western blot analysis revealed that LH dose-dependently increased the expression of Runx2 and ß-catenin, and promoted phosphorylation of glycogen synthase kinase-3ß in vitro. The in vivo results showed that administering LH (15 mg/kg/d) for 8 weeks alleviated destruction of the trabecular microstructure caused by osteoporosis. LH increased the bone mineral density and trabecular number, decreased trabecular separation according to a micro-computed tomography scan. In addition, LH enhanced the expression of ß-catenin and Runx2 in vivo. In conclusion, LH promoted osteogenic differentiation and bone formation in vivo and in vitro, which alleviated osteoporosis through activation of the Wnt/ß-catenin pathway.

Arbutin promotes MC3T3­E1 mouse osteoblast precursor cell proliferation and differentiation via the Wnt/ß­catenin signaling pathway.

Arbutin is a natural compound extracted from various plants, including bearberry leaves, that exerts multiple effects including skin whitening, anti­inflammatory and oxidative stress­protective properties. However, the effects of arbutin on osteoblasts remain unknown. The aim of the present study was to investigate the function and the mechanisms of arbutin on the proliferation and differentiation of MC3T3­E1 mouse osteoblast precursor cells in vitro. The proliferation of MC3T3­E1 cells treated with arbutin was assessed using a Cell Counting Kit­8 assay and a 5­ethynyl­2'­deoxyuridine labeling assay. Additionally, cell cycle and apoptosis were examined using flow cytometry analysis. The effects of arbutin on osteoblast differentiation were investigated using alkaline phosphatase (ALP) staining and by examining the mRNA expression levels of collagen type I α1 chain (COL1A1), bone γ­carboxyglutamate protein (BGLAP) and Sp7 transcription factor (SP7). To further investigate the molecular mechanism underlying arbutin function in promoting osteogenesis, the mRNA and protein expression levels of runt­related transcription factor 2 (RUNX2) and ß­catenin were analyzed by reverse transcription­quantitative polymerase chain reaction and western blotting. Arbutin significantly promoted MC3T3­E1 cell proliferation and increased the ratio of cells in S­phase. Treatment with arbutin increased ALP activity and the mRNA expression levels of COL1A1, BGLAP and SP7 in MC3T3­E1 cells. Furthermore, the protein and the mRNA expression levels of RUNX2 and ß­catenin increased significantly following treatment with arbutin. Collectively, the present findings suggested that arbutin was able to promote proliferation and differentiation of MC3T3­E1 cells via the Wnt/ß­catenin signaling pathway.