title: Combination of an allosteric Akt Inhibitor MK-2206 with etoposide or rapamycin enhances the antitumor growth effect in neuroblastoma.
abstract: OBJECTIVE
  Activation of Akt is a marker of decreased event-free or overall survival in neuroblastoma patients. MK-2206, a novel allosteric Akt inhibitor, is now tested in clinical trials in adult cancers. In this study, effect of MK-2206 on tumor growth and murine survival, alone or in combination, with etoposide or rapamycin was evaluated.
  
  
  METHODS
  The anticell proliferation effect of MK-2206 was tested in eight neuroblastoma cell lines by MTS assay. Caspase-3/7 activity, cell-cycle analysis, and reactive oxygen species (ROS) production were determined. Effect of MK-2206 combined with etoposide or rapamycin was evaluated in vitro and in vivo. Akt phosphorylation was measured by Western blotting in neuroblastoma cells and tumors.
  
  
  RESULTS
  In vitro, MK-2206 treatment inhibited neuroblastoma cell proliferation, which was accompanied by a cell line selective G(1) arrest of cell cycle or production of ROS. A synergistic effect between MK-2206 and etoposide was detected in four tested neuroblastoma cell lines via caspase-dependent apoptosis, whereas increased inhibition of cell growth induced by combination of MK-2206 and rapamycin was mediated by ROS production. In vivo, MK-2206 alone decreased tumor growth and increased murine survival at dose that inhibited Akt phosphorylation in tumors. MK-2206, in combination with etoposide or rapamycin, caused a significant decrease in tumor growth and increase of murine survival compared with MK-2206 alone.
  
  
  CONCLUSIONS
  Akt inhibition by MK-2206 increased the efficacy of etoposide or rapamycin. Our study supports future clinical evaluation of MK-2206 in combination with conventional cytotoxic therapy or with rapamycin in high-risk neuroblastoma patients.
authors.affiliation: Cell & Molecular Biology Section, Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA. lizhijie@mail.nih.gov
authors.forename: Zhijie
authors.initials: Z
authors.lastname: Li
authors.forename: Shuang
authors.initials: S
authors.lastname: Yan
authors.forename: Navid
authors.initials: N
authors.lastname: Attayan
authors.forename: Sridevi
authors.initials: S
authors.lastname: Ramalingam
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Thiele
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D005047:Etoposide / Q000008:administration & dosage; D005260:Female; D006575:Heterocyclic Compounds, 3-Ring / Q000008:administration & dosage; D006801:Humans; D020128:Inhibitory Concentration 50; D051379:Mice; D008819:Mice, Nude; D009447:Neuroblastoma / Q000188:drug therapy* / Q000201:enzymology; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020123:Sirolimus / Q000008:administration & dosage; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D006575:Heterocyclic Compounds, 3-Ring; C548887:MK 2206; D017382:Reactive Oxygen Species; D005047:Etoposide; D051057:Proto-Oncogene Proteins c-akt; D020123:Sirolimus