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Objective: To investigate the effect of inhibition and activation of MAPK-ERK1/2 pathway on the expression of osteogenic genes and proliferation of rat osteoblasts in vitro., Methods: Primarily cultured rat osteoblasts, identified by cell morphology studies and ALP staining, were exposed to 1% or 5% rat serum for 24 h or to the specific MAPK-ERK1/2 inhibitor PD0325901. The downstream molecules of MAPK-ERK1/2 pathway including p-ERK1/2 and ERK1/2, osteogenic genes such as Runx2 and Type I collagen, and proliferating cell nuclear antigen (PCNA) were detected by Western Blotting, and alkaline phosphatase activities were analyzed quantitatively., Results: Compared with 1% rat serum-treated cells, exposure of the cells to a higher concentration (5%) of rat serum caused a significantly increased phosphorylation level of p-ERK1/2 (P<0.05) and obviously enhanced expressions of the osteogenic genes (Runx2, type I collagen and ALP) and PCNA (P<0.05). Inhibition of the MAPK-ERK1/2 pathway with PD0325901 resulted in suppressed expressions of the osteogenic genes and PCNA., Conclusion: The activation of MAPK-ERK1/2 pathway promotes the expression of osteogenic genes such as Runx2, type I collagen and ALP and enhances the proliferative activity of the osteoblasts, while inhibition of this pathway suppresses the expressions of these genes and the cell proliferation, suggesting that this pathway may potentially serve as a therapeutic target for osteoporosis.

Background/Aims: Bone marrow-derived mesenchymal stem cells (MSCs) are responsible for new bone formation during adulthood. Accumulating evidences showed that Osthole promotes the osteogenic differentiation in primary osteoblasts. The aim of this study was to investigate whether Osthole exhibits a potential to stimulate the osteogenic differentiation of MSCs and the underlying mechanism. Methods: MSCs were treated with a gradient concentration of Osthole (6.25 μM, 12.5 μM, and 25 μM). Cell proliferation was assessed by western blotting with the proliferating cell nuclear antigen (PCNA) and Cyclin D1 antibodies, fluorescence activated cell sorting (FACS), and cell counting kit 8 (CCK8). MSCs were cultured in osteogenesis-induced medium for one or two weeks. The osteogenic differentiation of MSCs was estimated by Alkaline Phosphatase (ALP) staining, Alizarin red staining, Calcium influx, and quantitative PCR (qPCR). The underlying mechanism of Osthole-induced osteogenesis was further evaluated by western blotting with antibodies in Wnt/β-catenin, PI3K/Akt, BMPs/ smad1/5/8, and MAPK signaling pathways. Results: Osthole inhibited proliferation of rat MSCs in a dose-dependent manner. Osthole suppressed osteogenic differentiation of rat MSCs by down-regulating the activities of Wnt/β-catenin and Erk1/2-MAPK signaling. Conclusions: Osthole inhibits the proliferation and osteogenic differentiation of rat MSCs, which might be mediated through blocking the Wnt/β-catenin and Erk1/2-MAPK signaling pathways. [ABSTRACT FROM AUTHOR]

Background/Aims: Cartilage destruction is thought to be the major mediator of osteoarthritis. Recent studies suggest that inhibition of subchrondral bone loss by anti-osteoporosis (OP) drug can protect cartilige erosion. Osthole, as a promising agent for treating osteoporosis, may show potential in treating osteoarthritis. The purpose of this study was to investigate whether Osthole affects the proliferation and catabolism of rat chondrocytes, and the degeneration of cartilage explants. Methods: Rat chondrocytes were treated with Osthole (0 μM, 6.25 μM, 12.5 μM, and 25 μM) with or without IL1-ß (10ng/ml) for 24 hours. The expression levels of type II collagen and MMP13 were detected by western Blot. Marker genes for chondrocytes (A-can and Sox9), matrix metalloproteinases (MMPS), aggrecanases (ADAMTS5) and genes implicated in extracellular matrix catabolism were evaluated by qPCR. Cell proliferation was assessed by measuring proliferating cell nuclear antigen (PCNA) expression and fluorescence activated cell sorter. Wnt7b/ß-catenin signaling was also investigated. Cartilage explants from twoweek old SD rats were cultured with IL-1ß, Osthole and Osthole plus IL-1ß for four days and glycosaminoglycan (GAG) synthesis was assessed with toluidine blue staining and Safranine O/Fast Green FCF staining, collagen type II expression was detected by immunofluorescence. Results: Osthole reduced expression of chondrocyte markers and increased expression of MMP13, ADAMTS5 and MMP9 in a dose-dependent manner. Catabolic gene expression levels were further improved by Osthole plus IL-1ß. Osthole inhibited chondrocyte proliferation. GAG synthesis and type II collagen were decreased in both the IL-1ß groups and the Osthole groups, and significantly reduced by Osthole plus IL-1ß. Conclusions: Our data suggested that Osthole increases the catabolism of rat chondrocytes and cartilage explants, this effect might be mediated through inhibiting Wnt7b/ß-catenin pathway. [ABSTRACT FROM AUTHOR]

Aims: The purpose of this study was to investigate how Osthole affects glioma cell proliferation, apoptosis, invasion and migration. Methods: Rat glioma cells were treated with different concentrations of Osthole (0 µM, 25 µM, 50 µM, and 100 µM). Cell proliferation was assessed by measuring PCNA expression and CCK8 assay at different time points. Apoptosis was evaluated by measuring the expression of pro-apoptotic protein including Bax, Bcl2, PARP, and cleaved Caspase3, and of anti-apoptotic protein Survivin. Cell migration and invasion were assessed using different methods. Signaling pathways such as PI3K/Akt and MAPK, which are involved in the development of glioma cells, were also investigated in this study. Results: Treatment with Osthole markedly inhibits glioma cell proliferation, as assessed by western blot with the PCNA antibody. Osthole also induces cell apoptosis by upregulating the expression of pro-apoptotic proteins, and by reducing the expression of anti-apoptotic factors. Moreover, C6 cell migration and invasion were efficiently inhibited in groups treated with Osthole, compared to the control group. Additionally, inhibition of PI3K/Akt and MAPK signaling pathway was also observed in C6 cells treated with Osthole. Conclusions: Our findings showed an anti-cancer effect of Osthole on glioma cells, including the proliferation inhibition, apoptosis induction, and migration/invasion inhibition. Further investigation in C6 glioma cells implicated the role of Osthole in essential pathways controlling glioma cell progression. Taken together, our data suggested that Osthole may have a potential application in glioma therapy. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]