Calycosin induces apoptosis via p38­MAPK pathway­mediated activation of the mitochondrial apoptotic pathway in human osteosarcoma 143B cells.

Previous studies have demonstrated that calycosin is a natural phytoestrogen with a similar structure to estrogen, which can inhibit cell proliferation and induce apoptosis in a variety of tumors. Calycosin exerts potential pharmacological effects on osteosarcoma cells by inducing apoptosis. The aim of the present study was to elucidate the specific molecular mechanism of calycosin­induced apoptosis in osteosarcoma cells. Cell proliferation was determined by an MTT assay. Annexin V/PI and JC­1 staining were used to detect apoptosis and mitochondrial dysfunction, respectively, by flow cytometry. Western blot analysis was used to detect the expression of caspases or mitochondrial proteins. The results revealed that calycosin reduced the cell viability of human osteosarcoma 143B cells, induced apoptosis and increased the loss of mitochondrial membrane potential (MMP). In addition, calycosin increased the expression of the proapoptotic antiapoptotic proteins cleaved caspase­3, cleaved caspase­9, cleaved poly(ADP­ribose) polymerase and Bcl­2­associated X protein (Bax), and decreased the expression of the antiapoptotic proapoptotic protein B­cell lymphoma­2 (Bcl­2), thus altering the Bax/Bcl­2 ratio. In addition, the expression levels of cytochrome c were markedly decreased in the mitochondria and increased in the cytoplasm following calycosin treatment. Furthermore, calycosin treatment induced p38­mitogen­activated protein kinase (MAPK) phosphorylation, whereas the p38­MAPK inhibitor BIRB 796 markedly reversed cell viability, apoptosis and loss of MMP in 143B cells. These results suggested that calycosin inhibited osteosarcoma 143B cell growth via p38­MAPK regulation of mitochondrial­dependent intrinsic apoptotic pathways.

Calycosin induces apoptosis in osteosarcoma cell line via ERß­mediated PI3K/Akt signaling pathways.

Previous studies have shown that calycosin, a natural phytoestrogen which is structurally similar to estrogen, inhibits proliferation and induces apoptosis in estrogen­dependent cancer types via the estrogen receptor (ER)ß­induced inhibition of PI3K/Akt. Therefore, the aims of the present study were to investigate the effects of calycosin on human osteosarcoma (OS), and to examine the molecular mechanisms associated with ERß. Human OS MG­63 cells were treated with various concentrations of calycosin, and MTT and flow cytometry assays were used to assess the effects of calycosin on cellular proliferation and apoptosis. In addition, protein expression levels of ERß, phosphorylated (p)­PI3K, p­Akt, cleaved poly (ADP­ribose) polymerase 1 (PARP) and cleaved caspase­3 were evaluated by western blot analysis. The present results suggested that calycosin inhibited proliferation and induced apoptosis in MG­63 cells. Furthermore, increased ERß expression was detected in OS MG­63 cells treated with calycosin, and an ERß inhibitor (PHTPP) reversed calycosin­induced cytotoxicity and apoptosis. Moreover, phosphorylation levels of PI3K and Akt were significantly downregulated after calycosin treatment, whereas PHTPP reversed their phosphorylation. ERß­mediated PI3K/Akt downstream signaling pathways were found to influence the activity of poly (ADP­ribose) polymerase 1 and caspase­3. Thus, the present results indicated that calycosin inhibited proliferation and induced apoptosis in OS MG­63 cells, and that these effects were mediated by ERß­dependent inhibition of the PI3K/Akt pathways.

Combining the mammalian target of rapamycin inhibitor, rapamycin, with resveratrol has a synergistic effect in multiple myeloma.

Rapamycin is known to inhibit the mammalian target of rapamycin complex (mTORC)1 signaling pathway, but it is unable to effectively inhibit mTORC2, resulting in activation of protein kinase B in multiple myeloma (MM) cell lines. Additionally, certain studies have suggested that resveratrol has an effect on human MM cells, and that rapamycin in combination with resveratrol may be useful in cancer therapy. The present study aimed to investigate the combined treatment effect of resveratrol and rapamycin on the MM MM1.S cell line. The results demonstrated that combined treatment with rapamycin and resveratrol effectively inhibited cell viability in the MM1.S cell line through inhibition of the mTORC1 and mTORC2 signaling pathways, compared with resveratrol or rapamycin monotherapy. In addition, cyclin D1 levels were decreased and the activation of caspase-3 and poly (ADP-ribose) polymerase was increased. These results suggested that downregulation of the mTOR signaling cascades is likely to be a crucial mediator in the impairment of viability and the induction of apoptosis resulting from combined therapy with resveratrol and rapamycin in MM1.S cells.