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Osteoporosis is characterized by the progressive loss of bone mass and the micro-architectural deterioration of bone tissue, leading to bone fragility and an increased risk of fracture. Gallium has demonstrated efficacy in the treatment of several diverse disorders that are characterized by accelerated bone loss. Osteoblasts orchestrate bone degradation by expressing the receptor activator of NF-κB ligand (RANKL), however they additionally protect the skeleton by secreting osteoprotegerin (OPG). Therefore, the relative concentration of RANKL and OPG in bone is a key determinant of bone mass and strength. The current study demonstrated that gallium nitrate (GaN) is able to counteract bone loss in an experimental model of established osteoporosis. Ovariectomized (OVX) rats exhibited significantly increased bone mineral density following GaN treatment for 4 and 8 weeks by 19.3 and 37.3%, respectively (P<0.05). The bone volume of the OVX + GaN group was increased by 40.9% (P<0.05) compared with the OVX group. In addition, the current study demonstrated that GaN stimulates the synthesis of OPG however has no effect on the expression of RANKL in osteoblasts, as demonstrated by RT-qPCR, western blotting and ELISA, resulting in an increase in the OPG/RANKL ratio and a reduction in osteoclast differentiation in vivo and in vitro. [ABSTRACT FROM AUTHOR]

Malignant gliomas are a common type of primary tumor of the central nervous system. In spite of current intensive therapy, the prognosis of patients with malignant glioma remains poor, hence the development of novel therapeutic modalities is necessary. Cell apoptosis is a frequent target in the development of anti-cancer drugs. Fatsioside A, a novel baccharane-type triterpenoid glycoside, is extracted from the fruits of Fatsia japonica. Previous studies have shown that Fatsioside A induces growth inhibition, cell cycle arrest and apoptosis in C6 rat glioma cells and U251 human glioma cells. However, to the best of our knowledge, no detailed studies have reported its effect on U87MG glioma cells and its exact mechanisms remain unknown. In the current study, the growth inhibitory effect of Fatsioside A on U87MG cells was evaluated and the underlying molecular mechanisms were explored. Through the use of flow cytometry and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, it was determined that Fatsioside A markedly inhibits the growth of U87MG cells. Mechanistic studies demonstrated that Fatsioside A induces growth inhibition of U87MG cells via the induction of endoplasmic reticulum (ER) stress, which was supported by the upregulation of ER stress markers, including elevated levels of phosphorylation of PERK and eIF2α, the increased expression levels of CHOP and the accelerated cleavage of caspase-4. The downregulation of CHOP via CHOP-specific siRNA reduced the growth-inhibitive effect of Fatsioside A on U87MG cells, further confirming the role of the ER stress response in mediating Fatsioside A-induced growth inhibition. In conclusion, Fatsioside A inhibits glioma cell growth via the induction of ER stress-mediated apoptosis. This may provide a molecular basis for the development of Fatsioside A into a drug candidate for the treatment of malignant glioma. [ABSTRACT FROM AUTHOR]