title: MDM2 inhibition sensitizes neuroblastoma to chemotherapy-induced apoptotic cell death.
abstract: Novel therapeutic approaches are urgently needed for high-stage neuroblastoma, a major therapeutic challenge in pediatric oncology. The majority of neuroblastoma tumors are p53 wild type with intact downstream p53 signaling pathways. We hypothesize that stabilization of p53 would sensitize this aggressive tumor to genotoxic chemotherapy via inhibition of MDM2, the primary negative upstream regulator of p53. We used pharmacologic inhibition of the MDM2-p53 interaction with the small-molecule inhibitor Nutlin and studied the subsequent response to chemotherapy in neuroblastoma cell lines. We did 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and terminal deoxynucleotidyl transferase assays to measure proliferation and apoptosis in several cell lines (IMR32, MYCN3, and JF) treated with combinations of cisplatin, etoposide, and Nutlin. We found consistent and robust decreases in proliferation and increases in apoptosis with the addition of Nutlin 3a to etoposide or cisplatin in all cell lines tested and no response to the inactive Nutlin 3b enantiomer. We also show a rapid and robust accumulation of p53 protein by Western blot in these cells within 1 to 2 hours of treatment. We conclude that MDM2 inhibition dramatically enhances the activity of genotoxic drugs in neuroblastoma and should be considered as an adjuvant to chemotherapy for this aggressive pediatric cancer and for possibly other p53 wild-type solid tumors.
authors.affiliation: Texas Children's Cancer Center and Center for Cell and Gene Therapy, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Eveline
authors.initials: E
authors.lastname: Barbieri
authors.forename: Parth
authors.initials: P
authors.lastname: Mehta
authors.forename: Zaowen
authors.initials: Z
authors.lastname: Chen
authors.forename: Linna
authors.initials: L
authors.lastname: Zhang
authors.forename: Andrew
authors.initials: A
authors.lastname: Slack
authors.forename: Stacey
authors.initials: S
authors.lastname: Berg
authors.forename: Jason M
authors.initials: JM
authors.lastname: Shohet
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D004357:Drug Synergism; D045325:HCT116 Cells; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D051379:Mice; D009447:Neuroblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D010879:Piperazines / Q000494:pharmacology*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors*; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis
chemical_list: D000970:Antineoplastic Agents; D007093:Imidazoles; D010879:Piperazines; D016159:Tumor Suppressor Protein p53; C482205:nutlin 3; D051736:Proto-Oncogene Proteins c-mdm2