title: Synergistic activity of fenretinide and the Bcl-2 family protein inhibitor ABT-737 against human neuroblastoma.
abstract: OBJECTIVE
  Fenretinide (4-HPR) is a cytotoxic retinoid with minimal systemic toxicity that has shown clinical activity against recurrent high-risk neuroblastoma. To identify possible synergistic drug combinations for future clinical trials, we determined whether ABT-737, a small-molecule BH3-mimetic that inhibits most proteins of the antiapoptotic Bcl-2 family, could enhance 4-HPR activity in neuroblastoma.
  
  
  METHODS
  Eleven neuroblastoma cell lines were tested for the cytotoxic activity of 4-HPR and ABT-737 as single agents and in combination using the DIMSCAN fluorescence digital imaging cytotoxicity assay. The effect of these agents alone and in combination on mitochondrial membrane depolarization and apoptosis (by flow cytometry), cytochrome c release, caspases, Bax-α, t-Bid, and Bak activation, and subcutaneous xenografts in nu/nu mice was also determined.
  
  
  RESULTS
  Multilog synergistic cytotoxicity was observed for the drug combination in all of the 11 neuroblastoma cell lines tested, including MDR lines and those insensitive to either drug as single agents. 4-HPR + ABT-737 induced greater mitochondrial membrane depolarization and mitochondrial cytochrome c release, greater activation of caspases, Bax-α, t-Bid, and Bak, and a higher level of apoptosis than either drug alone. In vivo, 4-HPR + ABT-737 increased the event-free survival of the MDR human neuroblastoma line CHLA-119 implanted subcutaneously in nu/nu mice (194.5 days for the combination vs. 68 days for ABT-737 and 99 days for 4-HPR).
  
  
  CONCLUSIONS
  Thus, the combination of 4-HPR with a BH3-mimetic drug warrants clinical trials in recurrent neuroblastoma.
authors.affiliation: Division of Hematology-Oncology, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Fang
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Harned
authors.forename: Ondrej
authors.initials: O
authors.lastname: Kalous
authors.forename: Vanessa
authors.initials: V
authors.lastname: Maldonado
authors.forename: Yves A
authors.initials: YA
authors.lastname: DeClerck
authors.forename: C Patrick
authors.initials: CP
authors.lastname: Reynolds
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D001713:Biphenyl Compounds / Q000008:administration & dosage*; D020169:Caspases / Q000096:biosynthesis; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D018572:Disease-Free Survival; D005260:Female; D017313:Fenretinide / Q000008:administration & dosage*; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008819:Mice, Nude; D009447:Neuroblastoma / Q000188:drug therapy*; D009596:Nitrophenols / Q000008:administration & dosage*; D010879:Piperazines / Q000008:administration & dosage; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors; D013449:Sulfonamides / Q000008:administration & dosage*; D023041:Xenograft Model Antitumor Assays
chemical_list: C501332:ABT-737; D001713:Biphenyl Compounds; D009596:Nitrophenols; D010879:Piperazines; D019253:Proto-Oncogene Proteins c-bcl-2; D013449:Sulfonamides; D017313:Fenretinide; D045304:Cytochromes c; D020169:Caspases