title: MYCN sensitizes neuroblastoma to the MDM2-p53 antagonists Nutlin-3 and MI-63.
abstract: MYCN amplification is a major biomarker of poor prognosis, occurring in 25-30% of neuroblastomas. MYCN has contradictory roles in promoting cell growth and sensitizing cells to apoptosis. We have recently shown that p53 is a direct transcriptional target of MYCN in neuroblastoma and that p53-mediated apoptosis may be an important mechanism of MYCN-induced apoptosis. Although p53 mutations are rare in neuroblastoma at diagnosis, the p53/MDM2/p14(ARF) pathway is often inactivated through MDM2 amplification or p14(ARF) inactivation. We hypothesized that reactivation of p53 by inhibition of its negative regulator MDM2, using the MDM2-p53 antagonists Nutlin-3 and MI-63, will result in p53-mediated growth arrest and apoptosis especially in MYCN-amplified cells. Using the SHEP Tet21N MYCN-regulatable system, MYCN(-) cells were more resistant to both Nutlin-3 and MI-63 mediated growth inhibition and apoptosis compared with MYCN(+) cells and siRNA-mediated knockdown of MYCN in four MYCN-amplified cell lines resulted in decreased p53 expression and activation, as well as decreased levels of apoptosis following treatment with MDM2-p53 antagonists. In a panel of 18 neuroblastoma cell lines treated with Nutlin-3 and MI-63, the subset amplified for MYCN had a significantly lower mean GI(50) value (50% growth inhibition) and increased caspase 3/7 activity compared with the non-MYCN-amplified group of cell lines, but p53 mutant cell lines were resistant to the antagonists regardless of MYCN status. We conclude that amplification or overexpression of MYCN sensitizes neuroblastoma cell lines with wild-type p53 to MDM2-p53 antagonists and that these compounds may therefore be particularly effective in treating high-risk MYCN-amplified disease.
authors: Newcastle Cancer Centre at the Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, UK.
authors: L D
authors: LD
authors: Gamble
authors: U R
authors: UR
authors: Kees
authors: D A
authors: DA
authors: Tweddle
authors: J
authors: J
authors: Lunec
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005434:Flow Cytometry; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology*; D008954:Models, Biological; D009154:Mutation; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D013141:Spiro Compounds / Q000494:pharmacology*; D013752:Tetracycline / Q000494:pharmacology; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: D007093:Imidazoles; D007211:Indoles; C543589:MI-63 compound; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D010879:Piperazines; D013141:Spiro Compounds; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; C482205:nutlin 3; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D053148:Caspase 3; D053179:Caspase 7; D013752:Tetracycline