title: Bortezomib suppresses focal adhesion kinase expression via interrupting nuclear factor-kappa B.
abstract: OBJECTIVE
  Bortezomib is a potent proteasome inhibitor currently used to treat various malignancies with promising results. To explore the role of bortezomib in reducing cancer cell migration and inducing apoptosis, we evaluated the effects of bortezomib on the expression of focal adhesion kinase (FAK).
  
  
  METHODS
  Various types of cancer cells including lung cancer A549, H1299; a breast cancer MCF7; a hepatocellular carcinoma Huh7, and a tongue squamous cell carcinoma SCC-25 were treated with different concentrations of bortezomib or MG-132 as indicated for 24h. Protein and mRNA levels were determined by Western blotting and real-time PCR. Apoptosis was analyzed by caspase 3 cleavage and activity. FAK promoter and NFkappaB binding activities were measured by luciferase-reporter method. NFkappaB subunit p65 binding capacity was determined by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) analysis.
  
  
  RESULTS
  Both bortezomib and another proteasome inhibitor, MG-132, significantly reduced FAK expression, suppressed cancer cell migration and increased cell apoptosis. Results of real-time PCR and promoter activity assay revealed that bortezomib decreased FAK expression through transcriptional inactivation. Results of FAK promoter activity and ChIP assays in A549 and H1299 cells indicated that bortezomib suppressed FAK activity through a p53-independent pathway. Furthermore, reduction of NFkappaB binding capacity demonstrated by EMSA and ChIP assay suggested that NFkappaB plays an important role in bortezomib suppressing FAK expression.
  
  
  CONCLUSIONS
  These results suggested that FAK is downregulated by bortezomib through a proteasome-dependent NFkappaB inhibitory mechanism. Thus, FAK could be a potential molecular target of bortezomib for therapeutic strategy.
authors.affiliation: Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan, Miaoli County 35053, Taiwan.
authors.forename: Bor-Sheng
authors.initials: BS
authors.lastname: Ko
authors.forename: Tzu-Ching
authors.initials: TC
authors.lastname: Chang
authors.forename: Chien-Hung
authors.initials: CH
authors.lastname: Chen
authors.forename: Chia-Chia
authors.initials: CC
authors.lastname: Liu
authors.forename: Cheng-Chin
authors.initials: CC
authors.lastname: Kuo
authors.forename: Chiun
authors.initials: C
authors.lastname: Hsu
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Shen
authors.forename: Tang-Long
authors.initials: TL
authors.lastname: Shen
authors.forename: Vita M
authors.initials: VM
authors.lastname: Golubovskaya
authors.forename: Chung-Che
authors.initials: CC
authors.lastname: Chang
authors.forename: Song-Kun
authors.initials: SK
authors.lastname: Shyue
authors.forename: Jun-Yang
authors.initials: JY
authors.lastname: Liou
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects*; D015536:Down-Regulation; D024202:Electrophoretic Mobility Shift Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D006801:Humans; D020287:In Situ Nick-End Labeling; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D061988:Proteasome Inhibitors; D011719:Pyrazines / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000970:Antineoplastic Agents; D001897:Boronic Acids; D004791:Enzyme Inhibitors; D016328:NF-kappa B; D061988:Proteasome Inhibitors; D011719:Pyrazines; D000069286:Bortezomib; D051416:Focal Adhesion Protein-Tyrosine Kinases