title: Proteasome inhibitor MG-132 induces C6 glioma cell apoptosis via oxidative stress.
abstract: OBJECTIVE
  Proteasome inhibitors have been found to suppress glioma cell proliferation and induce apoptosis, but the mechanisms are not fully elucidated. In this study we investigated the mechanisms underlying the apoptosis induced by the proteasome inhibitor MG-132 in glioma cells.
  
  
  METHODS
  C6 glioma cells were used. MTT assay was used to analyze cell proliferation. Proteasome activity was assayed using Succinyl-LLVY-AMC, and intracellular ROS level was evaluated with the redox-sensitive dye DCFH-DA. Apoptosis was detected using fluorescence and transmission electron microscopy as well as flow cytometry. The expression of apoptosis-related proteins was investigated using Western blot analysis.
  
  
  RESULTS
  MG-132 inhibited C6 glioma cell proliferation in a time- and dose-dependent manner (the IC(50) value at 24 h was 18.5 μmol/L). MG-132 (18.5 μmol/L) suppressed the proteasome activity by about 70% at 3 h. It induced apoptosis via down-regulation of antiapoptotic proteins Bcl-2 and XIAP, up-regulation of pro-apoptotic protein Bax and caspase-3, and production of cleaved C-terminal 85 kDa PARP). It also caused a more than 5-fold increase of reactive oxygen species. Tiron (1 mmol/L) effectively blocked oxidative stress induced by MG-132 (18.5 μmol/L), attenuated proliferation inhibition and apoptosis in C6 glioma cells, and reversed the expression pattern of apoptosis-related proteins.
  
  
  CONCLUSIONS
  MG-132 induced apoptosis of C6 glioma cells via the oxidative stress.
authors.affiliation: Department of Neurosurgery, 1st Bethune Hospital of Jilin University, Changchun 130021, China.
authors.forename: Wen-hai
authors.initials: WH
authors.lastname: Fan
authors.forename: Yi
authors.initials: Y
authors.lastname: Hou
authors.forename: Fan-kai
authors.initials: FK
authors.lastname: Meng
authors.forename: Xiao-fei
authors.initials: XF
authors.lastname: Wang
authors.forename: Yi-nan
authors.initials: YN
authors.lastname: Luo
authors.forename: Peng-fei
authors.initials: PF
authors.lastname: Ge
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005910:Glioma / Q000188:drug therapy* / Q000473:pathology; D020128:Inhibitory Concentration 50; D007976:Leupeptins / Q000008:administration & dosage / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D061988:Proteasome Inhibitors; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D061988:Proteasome Inhibitors; D017382:Reactive Oxygen Species; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde