The Synergistic Effect of Reduced Graphene Oxide and Proteasome Inhibitor in the Induction of Apoptosis through Oxidative Stress in Breast Cancer Cell Lines.

Reduced graphene oxide (rGO) and a proteasome inhibitor (MG-132) are some of the most commonly used compounds in various biomedical applications. However, the mechanisms of rGO- and MG-132-induced cytotoxicity remain unclear. The aim of this study was to investigate the anticancer effect of rGO and MG-132 against ZR-75-1 and MDA-MB-231 breast cancer cell lines. The results demonstrated that rGO, MG-132 or a mix (rGO + MG-132) induced time- and dose-dependent cytotoxicity in ZR-75-1 and MDA-MB-231 cells. Apart from that, we found that treatment with rGO and MG-132 or the mix increased apoptosis, necrosis and induction of caspase-8 and caspase-9 activity in both breast cancer cell lines. Apoptosis and caspase activation were accompanied by changes in the ultrastructure of mitochondria in ZR-75-1 and MDA-MB-231 cells incubated with rGO. Additionally, in the analyzed cells, we observed the induction of oxidative stress, accompanied by increased apoptosis and cell necrosis. In conclusion, oxidative stress induces apoptosis in the tested cells. At the same time, both mitochondrial and receptor apoptosis pathways are activated. These studies provided new information on the molecular mechanisms of apoptosis in the ZR-75-1 and MDA-MB-231 breast cancer cell lines.

Effects of ubiquitin-proteasome inhibitor on the expression levels of TNF-α and TGF-ß1 in mice with viral myocarditis.

Effects of ubiquitin-proteasome system (UPS) inhibitor MG-132 on the expression levels of tumor necrosis factor-α (TNF-α) and transforming growth factor-ß1 (TGF-ß1) in mice with viral myocarditis were investigated to analyze the correlation of myocardial tissue score of mice between TNF-α and TGF-ß1. Eighty healthy male SPF mice aged 6 weeks were selected and 20 mice were randomly selected as the blank group. The blank group did not receive any intervention. Mortality rates of each group were recorded and compared on day 8 of modeling, and heart specimens from the remaining mice were histopathologically examined and the expression of mRNA and protein of TNF-α and TGF-ß1 in myocardial tissues were detected by western blot analysis. Correlation between mouse myocardial histopathologic scores and expression of protein of TNF-α and TGF-ß1 in myocardial tissues, as well as the expression of TNF-α and TGF-ß1 in myocardial tissue in VMC mice was analyzed. The expression levels of myocardial histopathological scores, mRNA and protein of TNF-α and TGF-ß1 in the blank and control group were significantly lower than those in the VMC and the MG-132 group. The myocardial histopathological scores, mRNA and TNF-α and TGF-ß1 protein in the MG-132 group were significantly lower than those in the VMC group (P<0.05). The expression of TNF-α and TGF-ß1 protein in myocardial tissues was positively correlated with the pathological score in myocardial tissue of mice (r=0.843, P<0.05; r=0.763, P<0.05), and there was a positive correlation between the expression of TNF-α and TGF-ß1 protein in myocardial tissues of VMC mice (r=0.672, P<0.05). UPS inhibitor MG-132, which can significantly alleviate the myocardial injury of VMC mice, reduced the expression of inflammatory factors in myocardial tissues, and improved the survival rate of mice, thus it is a potential new treatment for VMC.

Proteasome inhibitor MG132 induces thyroid cancer cell apoptosis by modulating the activity of transcription factor FOXO3a.

Proteasome inhibitors are promising antitumor drugs with preferable cytotoxicity in malignant cells and have exhibited clinical efficiency in several hematologic malignancies. P53-dependent apoptosis has been reported to be a major mechanism underlying. However, apoptosis can also be found in cancer cells with mutant-type p53, suggesting the involvement of p53-independent mechanism. Tumor suppressor forkhead Box O3 is another substrate of proteasomal degradation, which also functions partially through inducing apoptosis. The aim of this study was to explore the effect of proteasome inhibition on the expression and activity of forkhead Box O3 in thyroid cancer cells. Using flow cytometry, western blot, immunofluorescence staining and quantitative RT-PCR assays, we assessed proteasome inhibitor MG132-induced apoptosis in thyroid cancer cells and its effect on the expression and activity of forkhead Box O3. The resulted showed that MG132 induced significant apoptosis, and caused the accumulation of p53 protein in both p53 wild-type and mutant-type thyroid cancer cell lines, whereas the proapoptotic targets of p53 were transcriptionally upregulated only in the p53 wild-type cells. Strikingly, upon MG132 administration, the accumulation and nuclear translocation of transcription factor forkhead Box O3 as well as transcriptional upregulation of its proapoptotic target genes were found in thyroid cancer cells regardless of p53 status. Cell apoptosis was enhanced by ectopic overexpression while attenuated by silencing of forkhead Box O3. Altogether, we demonstrated that proteasome inhibitor MG132 induces thyroid cancer cell apoptosis at least partially through modulating forkhead Box O3 activity.

Intervention effect of proteasome inhibitor MG132 in rats with collagen-induced arthritis / 中国免疫学杂志

Objective:To explore the intervention effect of proteasome inhibitor MG132 in rats with collagen-induced arthritis(CIA),which resembles human rheumatoid arthritis(RA).Methods:Forty-eight female SD rats were randomly divided into three groups,including blank control group,CIA model group and MG132-treated group.There were sixteen rats in each group.Rats in CIA model group and MG132-treated model group were injected with type Ⅱ collagen to established CIA rats.21 days after the initial immunization,the rats in the MG132-treated model group were injected subcutaneously with 1 mg/kg MG132 once daily for 2 weeks.42 days after the initial immunization,the change of paw-swelling and the arthritis scores were determined.The synovial pathology examination was performed with HE staining.The 20S proteasome activity in synovial tissue was measured by fluorescence substrate assay.The expression of NF-κB/p65,IκBα in synovial tissue were analyzed by Western blot.Results:Proteasome inhibitor MG132 significantly attenuated the severity of arthritis and histopathological changes in CIA rats.Compared with the blank control group,the 20S proteasome activity was increased significantly in the CIA model group(P<0.05),and decreased after injection of MG132.Compared with CIA rats,the expression of NF-κB/p65 significantly decreased in rats treated with MG132(P<0.01).Compared with the blank control group,the expression of IκBα protein decreased in CIA model group.After injected with MG132,the protein was significantly increased(P<0.01).Conclusion:The proteasome inhibitor MG132 may attenuates the severity of arthritis and histopathological changes in CIA rats.These effects may be mediated through the inhibition of NF-κB activity.

Inhibitory effect of MG132 on proliferation, migration and epithelial-mesenchymal transition of human lens epithelial cells / 中华实验眼科杂志

Background The primary pathologic mechanism of posterior capsular opacification (PCO) is proliferation,migration and epithelial-mesenchymal transition (EMT) of residuary lens epithelial cells (LECs) after cataract extract surgery.Researches showed that MG132,a proteasome inhibitor,can attenuate the proliferation of bovine LECs,but its effect on human LECs remains unclear.Objective This study was to investigate the inhibitory effect of MG132 on proliferation,migration and differentiation of human LECs in vitro.Methods Human lens capsule were collected during the surgery.Human LECs were primarily cultured by explant method and passaged.The second or third generation of cells were incubated to 96-well plates at the density of 5×105/ml (200 μl/well) for 24 hours.Fibroblast growth factor-2 (FGF-2,10 mg/L),MG132 (10 μmol/L) or MG132+FGF-2 was added into the culture medium for 24 hours separately,and regular cultured cells served as the control group.The proliferation value (absorbance,A490) of the cells was assayed by MTT colorimetric method.A bare area was made by a sterile cotton swab in the cell layer,and migrated cell number in the blank zone was counted to evaluate the migration ability of the cells after 24 hours.Transforming growth factor-32(TGF-β2),MG132 or MG132+TGF-β2 was added into the culture medium for 24 hours separately,and the expression of fibronectin (FN) in the cells was detected using immunochemistry.Results The proliferation values (A490) of the cells were 0.582±0.020,0.723±0.010,0.434± 0.011 and 0.465±0.008 in the control group,FGF-2 group,MG132 group and MG132 + FGF-2 group,respectively,showing a significant difference among the groups (F =110.482,P＜0.01).The A value was significantly higher in the FGF-2 group and lower in the MG132 group and MG132+FGF-2 group than that of the control group (all at P＜ 0.05).The migrated cell number was 8.67 ± 1.08,11.58 ± 1.59,2.67 ± 0.09 and 2.75 ± 0.09 in the control group,FGF-2 group,MG132 group and MG132+FGF-2 group,respectively,with a significant difference among the groups (F=34.301,P＜0.01),and more cells in the blank zone were seen in the FGF-2 group and less cells were in the MG132 group and MG132+FGF-2 group in comparison with the control group (all at P＜0.05).Compared with the control group,the proliferative rate and migrating rate of the cells declined by 25.4％ and 75.0％ in the MG132 group as well as 20.1％ and 68.3％ in the MG132+FGF-2 group,but in the FGF-2 group,they increased by 24.2％ and 33.6％.The expressing levels (A value) of FN in the LECs were 1.242±0.023,2.329±0.113,1.043 ±0.021 and 1.163±0.018 in the control group,TGF-β2 group,MG132 group and MG132 +TGF-β2 group,respectively,with a significant difference among the groups (F =113.752,P＜0.01),a considerably increased expressing value was seen in the TGF-β2 group and decreased value was in the MG132 group and MG132+TGF-β2 group when compared with the control group (all at P＜0.05).Conclusions MG132 can effectively inhibit the proliferation,migration and differentiation of human LECs in vitro.