title: Tumor necrosis factor α stimulates Her-2 cleavage by activated caspase-8.
abstract: OBJECTIVE
  Her-2 over-expression has been correlated with a poor prognosis in patients with breast cancer. Now, we explored the effect of TNF-α treatment and/or NFĸB activation on Her-2 expression in MCF-7 breast adenocarcinoma cells.
  
  
  METHODS
  Stably transfected MCF-7 cell lines with pcDNA3.0, IĸBα MT, c-FLIP/control shRNA were established by FuGENE with the supplementation of G418 (500 µg /ml). Western blot and Real-time PCR were applied to assess the expression levels of protein and mRNA of target gene. In addition, caspase-8 activity was evaluated by the incubation with a caspase-8 fluorogenic substrate, Ac-IEPD-AMC using a spectrofluorometer.
  
  
  RESULTS
  It was uncovered that Her-2 was a new substrate for caspase-8 and that tumor necrosis factor α (TNF-α) stimulation resulted in a caspase-8-dependent Her-2 cleavage in MCF-7 breast adenocarcinoma cells defective for nuclear factor ĸB (NFĸB) activation. We demonstrated that the antiapoptotic transcription factor NFĸB counteracted this cleavage through the induction of caspase-8 inhibitor, c-FLIP.
  
  
  CONCLUSIONS
  we propose a novel mechanism in which NFĸB functions as a new antiapoptotic factor by counteracting TNF-α-triggered Her-2 cleavage.
authors.affiliation: Department of Oncosurgery, First Affiliated Hospital of Medical College of Xi'an Jiao Tong University, Xi'an, PR China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ning
authors.initials: N
authors.lastname: Du
authors.forename: Hong
authors.initials: H
authors.lastname: Ren
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D017209:Apoptosis; D001940:Breast / Q000276:immunology / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000276:immunology; D053181:Caspase 8 / Q000276:immunology*; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology*; D015854:Up-Regulation
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D053181:Caspase 8; D016328:NF-kappa B; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D014409:Tumor Necrosis Factor-alpha; C506386:CFLAR protein, human