title: Curcusone D, a novel ubiquitin-proteasome pathway inhibitor via ROS-induced DUB inhibition, is synergistic with bortezomib against multiple myeloma cell growth.
abstract: BACKGROUND
  Ubiquitin-proteasome pathway (UPP) plays a very important role in the degradation of proteins. Finding novel UPP inhibitors is a promising strategy for treating multiple myeloma (MM).
  
  
  METHODS
  Ub-YFP reporter assays were used as cellular UPP models. MM cell growth, apoptosis and overall death were evaluated with the MTS assay, Annexin V/PI dual-staining flow cytometry, poly (ADP-ribose) polymerase (PARP) cleavage, and PI uptake, respectively. The mechanism of UPP inhibition was analyzed by western blotting for ubiquitin, in vitro and cellular proteasomal and deubiquitinases (DUBs) activity assays. Cellular reactive oxygen species (ROS) were measured with H2DCFDA.
  
  
  RESULTS
  Curcusone D, identified as a novel UPP inhibitor, causes cell growth inhibition and apoptosis in MM cells. Curcusone D induced the accumulation of poly-ubiquitin-conjugated proteins but could not inhibit proteasomal activity in vitro or in cells. Interestingly, the mono-ubiquitin level and the total cellular DUB activity were significantly downregulated following curcusone D treatment. Furthermore, curcusone D could induce ROS, which were closely correlated with DUB inhibition that could be nearly completely reversed by NAC. Finally, curcusone D and the proteasomal inhibitor bortezomib showed a strong synergistic effect against MM cells.
  
  
  CONCLUSIONS
  Curcusone D is novel UPP inhibitor that acts via the ROS-induced inhibition of DUBs to produce strong growth inhibition and apoptosis of MM cells and synergize with bortezomib.
  
  
  CONCLUSIONS
  The anti-MM molecular mechanism study of curcusone D will promote combination therapies with different UPP inhibitors against MM and further support the concept of oxidative stress regulating the activity of DUBs.
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Mei-Na
authors.initials: MN
authors.lastname: Cao
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China. Electronic address: ybzhou@mail.shcnc.ac.cn.
authors.forename: Yu-Bo
authors.initials: YB
authors.lastname: Zhou
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: An-Hui
authors.initials: AH
authors.lastname: Gao
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Jia-Yi
authors.initials: JY
authors.lastname: Cao
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Li-Xin
authors.initials: LX
authors.lastname: Gao
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Li
authors.initials: L
authors.lastname: Sheng
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Xu
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Ming-Bo
authors.initials: MB
authors.lastname: Su
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Xian-Chao
authors.initials: XC
authors.lastname: Cao
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Meng-Meng
authors.initials: MM
authors.lastname: Han
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
authors.forename: Ming-Kui
authors.initials: MK
authors.lastname: Wang
authors.affiliation: National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China. Electronic address: jli@mail.shcnc.ac.cn.
authors.forename: Jia
authors.initials: J
authors.lastname: Li
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001897:Boronic Acids / Q000627:therapeutic use*; D000069286:Bortezomib; D045744:Cell Line, Tumor; D004224:Diterpenes / Q000494:pharmacology*; D006801:Humans; D031286:Jatropha / Q000737:chemistry*; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000473:pathology; D061988:Proteasome Inhibitors / Q000494:pharmacology*; D011719:Pyrazines / Q000627:therapeutic use*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D064570:Ubiquitin-Specific Proteases / Q000037:antagonists & inhibitors*
chemical_list: D001897:Boronic Acids; D004224:Diterpenes; D061988:Proteasome Inhibitors; D011719:Pyrazines; D017382:Reactive Oxygen Species; C000589205:curcusone D; D000069286:Bortezomib; D064570:Ubiquitin-Specific Proteases
keywords: Bortezomib; Curcusone D; Deubiquitinase; Multiple myeloma; ROS; Ubiquitin–proteasome pathway