title: Vorinostat-induced apoptosis in mantle cell lymphoma is mediated by acetylation of proapoptotic BH3-only gene promoters.
abstract: OBJECTIVE
  Mantle cell lymphoma (MCL) is an aggressive B-cell neoplasm with generally poor prognosis, for which current therapies have shown limited efficacy. Vorinostat is a histone deacetylase inhibitor (HDACi) that has been approved for the treatment of cutaneous T-cell lymphoma. Our purpose was to describe the molecular mechanism whereby vorinostat induces apoptosis in MCL with particular emphasis on the role of proapoptotic BH3-only proteins.
  
  
  METHODS
  The sensitivity to vorinostat was analyzed in eight MCL cell lines and primary cells from 10 MCL patients. Determination of vorinostat mechanism of action was done by flow cytometry, immunoblotting, HDAC activity assay kit, quantitative reverse transcription PCR, chromatin immunoprecipitation, and siRNA-mediated transfection.
  
  
  RESULTS
  Vorinostat inhibited total histone deacetylase activity leading to selective toxicity toward tumor cells. Vorinostat-mediated cell death implied the activation of mitochondrial apoptosis, as attested by BAX and BAK conformational changes, mitochondrial depolarization, reactive oxygen species generation, and subsequent caspase-dependent cell death. This phenomenon was linked to H4 hyperacetylation on promoter regions and consequent transcriptional activation of the proapoptotic BH3-only genes BIM, BMF, and NOXA. Selective knockdown of the three corresponding proteins rescued cells from vorinostat-induced apoptosis. Moreover, vorinostat enhanced the activity of the BH3-mimetic ABT-263 in MCL cells, leading to synergistic apoptosis induction.
  
  
  CONCLUSIONS
  These results indicated that transcriptional upregulation of BH3-only proteins plays an important role in the antitumoral activity of vorinostat in MCL, and that HDACi alone or in combination with BH3-mimetizing agents may represent a promising therapeutic approach for MCL patients.
authors.affiliation: Hematopathology Unit, Department of Pathology, Hospital Clínic, Institut D'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Sílvia
authors.initials: S
authors.lastname: Xargay-Torrent
authors.forename: Mónica
authors.initials: M
authors.lastname: López-Guerra
authors.forename: Ifigènia
authors.initials: I
authors.lastname: Saborit-Villarroya
authors.forename: Laia
authors.initials: L
authors.lastname: Rosich
authors.forename: Elias
authors.initials: E
authors.lastname: Campo
authors.forename: Gaël
authors.initials: G
authors.lastname: Roué
authors.forename: Dolors
authors.initials: D
authors.lastname: Colomer
mesh_terms: D000107:Acetylation / Q000187:drug effects; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000814:Aniline Compounds / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D004357:Drug Synergism; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D020522:Lymphoma, Mantle-Cell / Q000235:genetics* / Q000473:pathology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology; D000077337:Vorinostat
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000814:Aniline Compounds; C486655:BMF protein, human; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; C498702:PMAIP1 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D013449:Sulfonamides; D000077337:Vorinostat; D006655:Histone Deacetylases; C528561:navitoclax