title: Mechanisms of G1 cell cycle arrest and apoptosis in myeloma cells induced by hybrid-compound histone deacetylase inhibitor.
abstract: OBJECTIVE
  Histone deacetylase (HDAC) inhibitors are new therapeutic agents, used to treat various types of malignant cancers. In the present study, we investigated the effects of Ky-2, a hybrid-compound HDAC inhibitor, on the growth of mouse myeloma cells.
  
  
  METHODS
  Myeloma cells, HS-72, P3U1, and mouse normal cells were used in this study. Effect of HDAC inhibitors on cell viability was determined by WST-assay and trypan blue assay. Cell cycle was analyzed using flow cytometer. The expression of cell cycle regulatory and the apoptosis associated proteins were examined by Western blot analysis. Hoechst's staining was used to detect apoptotic cells.
  
  
  RESULTS
  Our findings showed that Ky-2 decreased the levels of HDACs, while it enhanced acetylation of histone H3. Myeloma cell proliferation was inhibited by Ky-2 treatment. Interestingly, Ky-2 had no cytotoxic effects on mouse normal cells. Ky-2 treatment induced G1-phase cell cycle arrest and accumulation of a sub-G1 phase population, while Western blotting analysis revealed that expressions of the cell cycle-associated proteins were up-regulated. Also, Ky-2 enhanced the cleavage of caspase-9 and -3 in myeloma cells, followed by DNA fragmentation. In addition, Ky-2 was not found to induce apoptosis in bcl-2 overexpressing myeloma cells.
  
  
  CONCLUSIONS
  These findings suggest that Ky-2 induces apoptosis via a caspase-dependent cascade and Bcl-2-inhibitable mechanism in myeloma cells.
authors.affiliation: Division of Infections and Molecular Biology, Kyushu Dental University, Japan.
authors.forename: Seiko
authors.initials: S
authors.lastname: Fujii
authors.forename: Toshinori
authors.initials: T
authors.lastname: Okinaga
authors.forename: Wataru
authors.initials: W
authors.lastname: Ariyoshi
authors.forename: Osamu
authors.initials: O
authors.lastname: Takahashi
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Iwanaga
authors.forename: Norikazu
authors.initials: N
authors.lastname: Nishino
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tominaga
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Nishihara
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D016193:G1 Phase; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009101:Multiple Myeloma / Q000473:pathology*
chemical_list: D056572:Histone Deacetylase Inhibitors