title: Effect of low doses of actinomycin D on neuroblastoma cell lines.
abstract: BACKGROUND
  Neuroblastoma is a malignant embryonal tumor occurring in young children, consisting of undifferentiated neuroectodermal cells derived from the neural crest. Current therapies for high-risk neuroblastoma are insufficient, resulting in high mortality rates and high incidence of relapse. With the intent to find new therapies for neuroblastomas, we investigated the efficacy of low-doses of actinomycin D, which at low concentrations preferentially inhibit RNA polymerase I-dependent rRNA trasncription and therefore, ribosome biogenesis.
  
  
  METHODS
  Neuroblastoma cell lines with different p53 genetic background were employed to determine the response on cell viability and apoptosis of low-dose of actinomycin D. Subcutaneously-implanted SK-N-JD derived neuroblastoma tumors were used to assess the effect of low-doses of actinomycin D on tumor formation.
  
  
  RESULTS
  Low-dose actinomycin D treatment causes a reduction of cell viability in neuroblastoma cell lines and that this effect is stronger in cells that are wild-type for p53. MYCN overexpression contributes to enhance this effect, confirming the importance of this oncogene in ribosome biogenesis. In the wild-type SK-N-JD cell line, apoptosis was the major mechanism responsible for the reduction in viability and we demonstrate that treatment with the MDM2 inhibitor Nutlin-3, had a similar effect to that of actinomycin D. Apoptosis was also detected in p53(-/-)deficient LA1-55n cells treated with actinomycin D, however, only a small recovery of cell viability was found when apoptosis was inhibited by a pan-caspase inhibitor, suggesting that the treatment could activate an apoptosis-independent cell death pathway in these cells. We also determined whether actinomycin D could increase the efficacy of the histone deacetylase inhibitor, SAHA, which is in being used in neuroblastoma clinical trials. We show that actinomycin D synergizes with SAHA in neuroblastoma cell lines. Moreover, on subcutaneously-implanted neuroblastoma tumors derived from SK-N-JD cells, actinomycin D led to tumor regression, an effect enhanced in combination with SAHA.
  
  
  CONCLUSIONS
  The results presented in this work demonstrate that actinomycin D, at low concentrations, inhibits proliferation and induces cell death in vitro, as well as tumor regression in vivo. From this study, we propose that use of ribosome biogenesis inhibitors should be clinically considered as a potential therapy to treat neuroblastomas.
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Facultat de Farmàcia, Universitat de Barcelona, Avinguda Diagonal 643, 08028, Barcelona, Catalonia, Spain.|Laboratory of Cancer Metabolism, IDIBELL, Hospital Duran i Reynals, 08908 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain.
authors.forename: Constanza L
authors.initials: CL
authors.lastname: Cortes
authors.affiliation: Laboratory of Cancer Metabolism, IDIBELL, Hospital Duran i Reynals, 08908 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain.
authors.forename: Sonia R
authors.initials: SR
authors.lastname: Veiga
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Facultat de Farmàcia, Universitat de Barcelona, Avinguda Diagonal 643, 08028, Barcelona, Catalonia, Spain.|Laboratory of Cancer Metabolism, IDIBELL, Hospital Duran i Reynals, 08908 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain.
authors.forename: Eugènia
authors.initials: E
authors.lastname: Almacellas
authors.affiliation: Pathology Department, Hospital Universitari Vall d'Hebron, Universitat Autónoma de Barcelona, 08035, Barcelona, Catalonia, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Hernández-Losa
authors.affiliation: Pathology Department, Hospital Universitari Vall d'Hebron, Universitat Autónoma de Barcelona, 08035, Barcelona, Catalonia, Spain.
authors.forename: Joan C
authors.initials: JC
authors.lastname: Ferreres
authors.affiliation: Laboratory of Cancer Metabolism, Institut Català d'Oncologia, Hospital Duran i Reynals, 08908 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain.|Division of Hematology and Oncology, Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati, Ohio, 45267, USA.
authors.forename: Sara C
authors.initials: SC
authors.lastname: Kozma
authors.affiliation: Unit de Biochemistry, Department of Physiological Sciences II, Faculty of Medicine, Campus Universitari de Bellvitge - IDIBELL, University of Barcelona, 08908 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: Ambrosio
authors.affiliation: Laboratory of Cancer Metabolism, Institut Català d'Oncologia, Hospital Duran i Reynals, 08908 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain.|Division of Hematology and Oncology, Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati, Ohio, 45267, USA.|Unit de Biochemistry, Department of Physiological Sciences II, Faculty of Medicine, Campus Universitari de Bellvitge - IDIBELL, University of Barcelona, 08908 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain.
authors.forename: George
authors.initials: G
authors.lastname: Thomas
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Facultat de Farmàcia, Universitat de Barcelona, Avinguda Diagonal 643, 08028, Barcelona, Catalonia, Spain. tauler@ub.edu.|Laboratory of Cancer Metabolism, IDIBELL, Hospital Duran i Reynals, 08908 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain. tauler@ub.edu.
authors.forename: Albert
authors.initials: A
authors.lastname: Tauler
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003609:Dactinomycin / Q000494:pharmacology / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D006877:Hydroxamic Acids / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D051379:Mice; D009447:Neuroblastoma / Q000188:drug therapy* / Q000473:pathology; D010879:Piperazines / Q000494:pharmacology; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D000077337:Vorinostat
chemical_list: D006877:Hydroxamic Acids; D007093:Imidazoles; D010879:Piperazines; D016271:Proto-Oncogene Proteins c-myc; D016159:Tumor Suppressor Protein p53; D003609:Dactinomycin; C482205:nutlin 3; D000077337:Vorinostat