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OBJECTIVE: To investigate the influences of rapamycin on proliferation and apoptosis of human osteosarcoma MG-63 cells and the mechanisms of action. MATERIALS AND METHODS: The human osteosarcoma MG-63 cells were randomly divided into Control group, Rapamycin group, and Rapamycin + Beclin-1 plasmid transfection group. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was adopted to detect the viability of MG-63 cells in each group, and the 5-Ethynyl-2'-deoxyuridine (EdU) staining and Hoechst staining were applied to determine the proliferation and apoptosis, respectively, of MG-63 cells in each group. The levels of B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) were measured using enzyme-linked immunosorbent assay (ELISA) kits, and the protein expression levels of Beclin-1 and Vps34 in each group of MG-63 cells were tested using the Western blotting. RESULTS: Compared with the Control group, Rapamycin group, and Rapamycin + Beclin-1 plasmid transfection group had markedly weakened the viability of MG-63 cells, inhibited cell proliferation, remarkably increased cell apoptosis rate, elevated Bax level, notably declined Bcl-2 level, and significantly raised the levels of Beclin-1 and Vps34 proteins in MG-63 cells. Besides, the effects in Beclin-1 plasmid transfection group were stronger. CONCLUSIONS: Rapamycin may decrease the viability, inhibit the proliferation, and promote the apoptosis of MG-63 cells by activating autophagy. [ABSTRACT FROM AUTHOR]

Purpose Drug resistance has been recognized to be a major obstacle to the chemotherapy for osteosarcoma. And the potential importance of hypoxia as a target to reverse drug resistance in osteosarcoma has been indicated, though the mechanism underlining such role is not clarified. The present study aims to investigate the role of hypoxia in the drug resistance in osteosarcoma cells via activating AMP-activated protein kinase (AMPK) signaling. Experimental design We investigated the promotion of the resistance to doxorubicin of osteosarcoma MG-63 and U2-os cells in vitro, and then determined the role of hypoxia-inducible factor-1 (HIF-1)α and HIF-1β, the activation and regulatory role of AMPK in the osteosarcoma U2-os cells which were treated with doxorubicin under hypoxia. Results It was demonstrated that hypoxia significantly reduced the sensitivity of MG-63 and U2-os cells to doxorubicin, indicating an inhibited viability reduction and a reduced apoptosis promotion. And such reduced sensitivity was not associated with HIF-1α, though it was promoted by hypoxia in U2-os cells. Interestingly, the AMPK signaling was significantly promoted by hypoxia in the doxorubicin-treated U2-os cells, with a marked upregulation of phosphorylated AMPK (Thr 172) and phosphorylated acetyl-CoA carboxylase (ACC) (Ser 79), which were sensitive to the AMPK activator, AICAR and the AMPK inhibitor, Compound C. Moreover, the promoted AMPK activity by AICAR or the downregulated AMPK activity by Compound C significantly reduced or promoted the sensitivity of U2-os cells to doxorubicin. Conclusion The present study confirmed the AMPK signaling activation in the doxorubicin-treated osteosarcoma cells, in response to hypoxia, and the chemical upregulation or downregulation of AMPK signaling reduced or increased the chemo-sensitivity of osteosarcoma U2-os cells in vitro. Our study implies that AMPK inhibition might be a effective strategy to sensitize osteocarcoma cells to chemotherapy. [ABSTRACT FROM AUTHOR]

Summary: Background: Osteosarcoma is a common malignant bone tumor which threatens the life of young people worldwide. To explore alternative strategy for combating osteosarcoma, a light-emitting diode (LED) that activates methylene blue (MB) was used in the present study to investigate cell death of osteosarcoma-derived UMR106 cells. Materials and methods: Photocytotoxicity in UMR106 cells was investigated 24h after photodynamic activation of MB using sulforhodamine B (SRB) assay and light microscopy. Apoptosis induction was observed 24h after photodynamic treatment using a confocal laser scanning microscopy (CLSM) with Hoechst 33342 staining. The change in mitochondrial membrane potential (MMP) was analyzed using a flow cytometry with rhodamine 123 staining. Results: MB under red light irradiation caused a drug-concentration (0–100μM) and light-dose (0–32J/cm2) dependent cytotoxicity in UMR106 cells. The SRB assay and light microscopy observed a significant decrease in the number of UMR106 cells attached to the bottom of culture well after LED light-activated MB (100μM, 32J/cm2). Nuclear shrinkage, chromatin condensation and fragmentation were found in the treated cells by nuclear staining. In addition, flow cytometry showed that the MMP in UMR106 cells was rapidly reduced by photo-activated MB (100μM, 32J/cm2). Conclusion: Photodynamic action of MB under LED irradiation could remarkably kill osteosarcoma cells and induce cell apoptosis as well as MMP collapse. [Copyright &y& Elsevier]

• Cichorium Pumilum was encapsulated by silica nanoparticles to support the photodynamic therapy. • Photodynamic therapy was applied on Osteosarcoma cells by activate the encapsulated Cichorium Pumilum. • Optimal CP-SiNPs concentration and exposure time were measured and compared with naked CP. Silica nanoparticles (SiNPs) have been promising vehicles for drug delivery. Cichorium Pumilum (CP), a natural photosensitizer (PS), has been reported to have many useful effects in cancer treatment. However, the poor water solubility and its low bioavailability have confined its use as a suitable photosensitizer for photodynamic therapy. Therefore, a subtle approach is required to overcome these drawbacks. We have synthesized a silica nanoparticles loaded with Cichorium Pumilum. The nanoparticles structural morphologies have been charectrized by Transmission Electron Microscopy (TEM). The cytotoxicity for different concentrations of naked and encapsulated CP was evaluated. Moreover, the optimal concentration of naked and encapsulated CP with exposure time to a light (Maximum intensity at 350nm ∼0.27mW/cm2) required to eliminate the used cells (Osteosarcoma cells) were also measured. The results showed that encapsulated CP in SiNPs exhibited relatively higher efficacy than the naked CP by + 157.14 % of exposure time efficacy and + 49.45% of concentration efficacy, and encapsulated CP was also confirmed to be effective in eradicating osteosarcoma cells. The engineered silica nanoparticles loaded with CP enhanced the photodynamic therapy by increasing the CP bioavailability. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Objective: This study investigated the effects of rh-TRAIL with or without chemotherapeutic drugs on the apoptosis of the osteosarcoma cell line, MG-63, and the influence of chemotherapeutic drugs on changes in the expression of DR5 and Yin Yang1(YY1) in MG- 63 cells. Methods: The effects of treatment with rh-TRAIL alone and/or chemotherapeutic drugs on MG-63 cell growth inhibition and apoptosis were measured using the MTT assay, FACS analysis of Annexin V labeled cells, and the mRNA changes of DR5 and YY1 were detected by RT-PCR. Results: Rh-TRAIL protein inhibited the growth of MG-63 cells, and this inhibition was increased by adriamycin and IFN-γ. Adriamycin and IFN-γ significantly facilitated the induction of the expression of DR5 and reduced the expression of YY1. Conclusion: The apoptosis-inducing effect of rh-TRAIL in MG-63 cells was enhanced by chemotherapeutic drugs. [Copyright &y& Elsevier]

Abstract: The special extract ERr 731® from the roots of Rheum rhaponticum is the major constituent of Phytoestrol® N which is used for the alleviation of menopausal symptoms. Recently, we demonstrated that ERr 731® and its aglycones trans-rhapontigenin and desoxyrhapontigenin as single test substances do not activate the estrogen receptor-α (ERα) in human endometrial adenoarcinoma cells. However, these substances together with the structurally related hydroxystilbenes cis-rhapontigenin, resveratrol and piceatannol activated the ERβ-dependent reporter gene activity. To investigate if these substances are tissue selective ER activators, ERr 731® and the single test substances were examined in bone-derived U2OS cells stably expressing ERα or transiently expressing ERβ. In the ERα expressing U2OS cells, a weak, but statistically significant ERα-coupled luciferase activity was detected with ERr 731® and desoxyrhapontigenin which was 10-times lower than with 10−8 M 17β-estradiol. In the ERβ test system, all test substances significantly induced the luciferase activity in a magnitude comparable to 17β-estradiol. All effects were abolished with the pure ER antagonist ICI 182 780, indicating an ER-specific effect. Intracellular actions were also examined with the glycosylated ERr 731® constituents rhaponticin and desoxyrhaponticin. Treatment of U2OS cells with defined mixtures of both glycosides resulted in a reporter gene activity comparable to that of ERr 731®, thereby providing evidence for the existence of cellular uptake mechanisms for glycosylated hydroxystilbenes. This report confirms the strong ERβ-dependent activity of ERr 731® and provides evidence for a tissue selective ER agonistic activity by ERr 731® and its aglycones, as demonstrated by the activation of ERα in bone cells but not in endometrial cells. [Copyright &y& Elsevier]