title: Synergistic effect of histone deacetylase inhibitors FK228 and m-carboxycinnamic acid bis-hydroxamide with proteasome inhibitors PSI and PS-341 against gastrointestinal adenocarcinoma cells.
abstract: OBJECTIVE
  We investigated whether the histone deacetylase inhibitors m-carboxycinnamic acid bis-hydroxamide (CBHA) and a bicyclic depsipeptide, FK228, can enhance the anticancer effect of the proteasome inhibitors PSI and PS-341 in gastrointestinal carcinoma cells.
  
  
  METHODS
  The anticancer effect of CBHA or FK228 and PSI or PS-341 was evaluated by cell death, caspase-3 activity, externalization of phosphatidylserine and DNA fragmentation, and colony formation assay. Expression of apoptosis-related molecules and cell cycle regulatory molecules, as well as phosphorylation of p38 were investigated by immunoblots. Generation of reactive oxygen species (ROS) was detected by intracellular oxidation of 5- (and-6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate.
  
  
  RESULTS
  CBHA or FK228 plus PSI or PS-341 synergistically induced apoptosis in human colonic DLD-1 and gastric MKN45 carcinoma cell lines. CBHA or FK228, but not 5-fluorouracil, plus PS-341 strongly decreased plating efficiency of DLD-1 cells. FK228 elicited ROS generation, and the free radical scavenger l-N-acetylcysteine inhibited the synergistic anticancer effect of combined therapy. In addition, l-N-acetylcysteine inhibited the combined therapy-mediated elevation of a proapoptotic BH3-only protein Bim expression, phosphorylation of H2AX, and accumulation of 8-hydroxydeoxyguanosine.
  
  
  CONCLUSIONS
  FK228 or CBHA and PSI or PS-341 synergistically induce apoptosis in DLD-1 and MKN45 cells depending on ROS-mediated signals. Our data suggest that a combination of FK228 or CBHA with PSI or PS-341 may be a valuable therapy against gastrointestinal adenocarcinoma cells.
authors.affiliation: Graduate School of Medicine and First Department of Internal Medicine, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan. adachi@sapmed.ac.jp
authors.forename: Masaaki
authors.initials: M
authors.lastname: Adachi
authors.forename: YuBin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xudong
authors.initials: X
authors.lastname: Zhao
authors.forename: Takae
authors.initials: T
authors.lastname: Minami
authors.forename: Rina
authors.initials: R
authors.lastname: Kawamura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hinoda
authors.forename: Kohzoh
authors.initials: K
authors.lastname: Imai
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy*; D017304:Annexin A5 / Q000494:pharmacology; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis; D015153:Blotting, Western; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002934:Cinnamates / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000378:metabolism; D053938:DNA Fragmentation; D047630:Depsipeptides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005609:Free Radicals; D005770:Gastrointestinal Neoplasms / Q000188:drug therapy*; D006657:Histones / Q000378:metabolism; D006801:Humans; D018613:Microscopy, Confocal; D009842:Oligopeptides / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism; D010766:Phosphorylation; D061988:Proteasome Inhibitors; D011719:Pyrazines / Q000494:pharmacology*; D017382:Reactive Oxygen Species; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D017304:Annexin A5; D000903:Antibiotics, Antineoplastic; D001897:Boronic Acids; D002934:Cinnamates; D047630:Depsipeptides; D004791:Enzyme Inhibitors; D005609:Free Radicals; D006657:Histones; D009842:Oligopeptides; D061988:Proteasome Inhibitors; D011719:Pyrazines; D017382:Reactive Oxygen Species; C090535:benzyloxycarbonyl-isoleucyl-glutamyl(O-tert-butyl)-alanyl-leucinal; C111238:carboxycinnamic acid bishydroxamide; D000069286:Bortezomib; C087123:romidepsin; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D010100:Oxygen