title: MLN4924 sensitizes monocytes and maturing dendritic cells for TNF-dependent and -independent necroptosis.
abstract: OBJECTIVE
  MLN4924 prevents the formation of active cullin-RING ubiquitin ligase complexes and thus inhibits NF-κB signalling. Here, we evaluated the effects of this compound on monocytes and dendritic cells (DCs).
  
  
  METHODS
  Monocytes and DCs were challenged with TNF or LPS in the presence and absence of MLN4924. The effects of MLN4924 on cellular viability, pro-inflammatory gene induction and DC maturation were investigated using the MTT assay, elisa and FACS analysis. Mechanisms of cell death induction were evaluated by using inhibitors of caspases, RIPK1 and MLKL.
  
  
  RESULTS
  MLN4924 inhibited NF-κB activation and sensitized monocytes and immature DCs (iDCs) for TNFR1-induced cell death. Neither the caspase inhibitor zVAD-fmk, the RIPK1 inhibitor necrostatin-1 (nec-1) nor the MLKL inhibitor necrosulfonamide (NSA) alone prevented TNF-induced cell death. A combination of zVAD-fmk and nec-1 or NSA, however, rescued monocytes and iDCs from MLN4924/TNF-induced cell death indicating that MLN4924 affects anti-apoptotic and anti-necrotic activities in TNFR1 signalling. MLN4924 also converted the response of iDCs to LPS from maturation to cell death. LPS-induced cell death in MLN4924-treated iDCs was again only effectively blocked by cotreatment with zVAD-fmk and nec-1 or NSA. Noteworthy, MLN4924/LPS-induced cell death was almost completely independent of endogenous TNF. MLN4924 also strongly inhibited maturation and activation of iDCs that were rescued from cell death by zVAD-fmk and nec-1.
  
  
  CONCLUSIONS
  Our data reveal a strong dual suppressive effect of MLN4924 on DC activity. The targeting of NAE by MLN4924 could be a new way to treat inflammatory diseases.
authors.affiliation: Division of Molecular Internal Medicine, Department of Internal Medicine II, University Hospital Würzburg, Würzburg, Germany; Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: El-Mesery
authors.forename: Axel
authors.initials: A
authors.lastname: Seher
authors.forename: Thorsten
authors.initials: T
authors.lastname: Stühmer
authors.forename: Daniela
authors.initials: D
authors.lastname: Siegmund
authors.forename: Harald
authors.initials: H
authors.lastname: Wajant
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D003517:Cyclopentanes / Q000737:chemistry / Q000494:pharmacology*; D003713:Dendritic Cells / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009000:Monocytes / Q000187:drug effects*; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D009336:Necrosis / Q000188:drug therapy*; D011743:Pyrimidines / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D003517:Cyclopentanes; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011743:Pyrimidines; D014409:Tumor Necrosis Factor-alpha; C539933:pevonedistat