title: Histone deacetylase 1 gene expression and sensitization of multidrug-resistant neuroblastoma cell lines to cytotoxic agents by depsipeptide.
abstract: BACKGROUND
  Genes that are overexpressed in multidrug-resistant neuroblastomas relative to drug-sensitive neuroblastomas may provide targets for modulating drug resistance.
  
  
  METHODS
  We used microarrays to compare the gene expression profile of two drug-sensitive neuroblastoma cell lines with that of three multidrug-resistant neuroblastoma cell lines. RNA expression of selected overexpressed genes was quantified in 17 neuroblastoma cell lines by reverse transcription-polymerase chain reaction (RT-PCR). Small-interfering RNAs (siRNAs) were used for silencing gene expression. Cytotoxicity of melphalan, carboplatin, etoposide, and vincristine and cytotoxic synergy (expressed as combination index calculated by CalcuSyn software, where combination index < 1 indicates synergy and > 1 indicates antagonism) were measured in cell lines with a fluorescence-based assay of cell viability. All statistical tests were two-sided.
  
  
  RESULTS
  A total of 94 genes were overexpressed in the multidrug-resistant cell lines relative to the drug-sensitive cell lines. Nine genes were selected for RT-PCR analysis, of which four displayed higher mRNA expression in the multidrug-resistant lines than in the drug-sensitive lines: histone deacetylase 1 (HDAC1; 2.3-fold difference, 95% confidence interval [CI] = 1.0-fold to 3.5-fold, P = .025), nuclear transport factor 2-like export factor (4.2-fold difference, 95% CI = 1.7-fold to 7.6-fold, P = .0018), heat shock 27-kDa protein 1 (2.5-fold difference, 95% CI = 1.0-fold to 87.7-fold, P = .028), and TAF12 RNA polymerase II, TATA box-binding protein-associated factor, 20 kDa (2.2-fold, 95% CI = 0.9-fold to 6.0-fold, P = .051). siRNA knockdown of HDAC1 gene expression sensitized CHLA-136 neuroblastoma cells to etoposide up to fivefold relative to the parental cell line or scrambled siRNA-transfected cells (P<.001). Cytotoxicity of the histone deacetylase inhibitor depsipeptide was tested in combination with melphalan, carboplatin, etoposide, or vincristine in five multidrug-resistant neuroblastoma cell lines, and synergistic cytotoxicity was demonstrated at a 90% cell kill of treated cells (combination index < 0.8) in all cell lines.
  
  
  CONCLUSIONS
  High HDAC1 mRNA expression was associated with multidrug resistance in neuroblastoma cell lines, and inhibition of HDAC1 expression or activity enhanced the cytotoxicity of chemotherapeutic drugs in multidrug-resistant neuroblastoma cell lines. Thus, HDAC1 is a potential therapeutic target in multidrug-resistant neuroblastoma.
authors.affiliation: Institute for Pediatric Clinical Research and Division of Hematology-Oncology, Childrens Hospital Los Angeles, University of South California, Los Angeles, CA 90027, USA. nkeshelava@chla.usc.edu
authors.forename: Nino
authors.initials: N
authors.lastname: Keshelava
authors.forename: Elai
authors.initials: E
authors.lastname: Davicioni
authors.forename: Zesheng
authors.initials: Z
authors.lastname: Wan
authors.forename: Lingyun
authors.initials: L
authors.lastname: Ji
authors.forename: Richard
authors.initials: R
authors.lastname: Sposto
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Triche
authors.forename: C Patrick
authors.initials: CP
authors.lastname: Reynolds
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D047630:Depsipeptides / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000187:drug effects / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005047:Etoposide / Q000494:pharmacology; D015870:Gene Expression; D020869:Gene Expression Profiling; D052138:Genes, Neoplasm; D056284:Histone Deacetylase 1; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000235:genetics*; D006657:Histones / Q000378:metabolism; D006801:Humans; D009447:Neuroblastoma / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000032:analysis; D034741:RNA, Small Interfering / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D047630:Depsipeptides; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D005047:Etoposide; C110550:HDAC1 protein, human; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases