title: Tumor development, growth characteristics and spectrum of genetic aberrations in the TH-MYCN mouse model of neuroblastoma.
abstract: BACKGROUND
  The TH-MYCN transgenic neuroblastoma model, with targeted MYCN expression to the developing neural crest, has been used to study neuroblastoma development and evaluate novel targeted tumor therapies.
  
  
  METHODS
  We followed tumor development in 395 TH-MYCN (129X1/SvJ) mice (125 negative, 206 hemizygous and 64 homozygous mice) by abdominal palpations up to 40 weeks of age. DNA sequencing of MYCN in the original plasmid construct and mouse genomic DNA was done to verify the accuracy. Copy number analysis with Affymetrix® Mouse Diversity Genotyping Arrays was used to characterize acquired genetic aberrations.
  
  
  RESULTS
  DNA sequencing confirmed presence of human MYCN cDNA in genomic TH-MYCN DNA corresponding to the original plasmid construct. Tumor incidence and growth correlated significantly to transgene status with event-free survival for hemizygous mice at 50%, and 0% for homozygous mice. Hemizygous mice developed tumors at 5.6-19 weeks (median 9.1) and homozygous mice at 4.0-6.9 weeks (5.4). The mean treatment window, time from palpable tumor to sacrifice, for hemizygous and homozygous mice was 15 and 5.2 days, respectively. Hemizygous mice developing tumors as early as homozygous mice had a longer treatment window. Age at tumor development did not influence treatment window for hemizygous mice, whereas treatment window in homozygous mice decreased significantly with increasing age. Seven out of 10 analysed tumors had a flat DNA profile with neither segmental nor numerical chromosomal aberrations. Only three tumors from hemizygous mice showed acquired genetic features with one or more numerical aberrations. Of these, one event corresponded to gain on the mouse equivalent of human chromosome 17.
  
  
  CONCLUSIONS
  Hemizygous and homozygous TH-MYCN mice have significantly different neuroblastoma incidence, tumor growth characteristics and treatment windows but overlap in age at tumor development making correct early genotyping essential to evaluate therapeutic interventions. Contrasting previous studies, our data show that TH-MYCN tumors have few genetic aberrations.
authors.affiliation: Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden. Agnes.Rasmuson@ki.se
authors.forename: Agnes
authors.initials: A
authors.lastname: Rasmuson
authors.forename: Lova
authors.initials: L
authors.lastname: Segerström
authors.forename: Maria
authors.initials: M
authors.lastname: Nethander
authors.forename: Jennie
authors.initials: J
authors.lastname: Finnman
authors.forename: Lotta H M
authors.initials: LH
authors.lastname: Elfman
authors.forename: Niloufar
authors.initials: N
authors.lastname: Javanmardi
authors.forename: Staffan
authors.initials: S
authors.lastname: Nilsson
authors.forename: John Inge
authors.initials: JI
authors.lastname: Johnsen
authors.forename: Tommy
authors.initials: T
authors.lastname: Martinsson
authors.forename: Per
authors.initials: P
authors.lastname: Kogner
mesh_terms: D000818:Animals; D001947:Breeding; D049109:Cell Proliferation; D056915:DNA Copy Number Variations; D004195:Disease Models, Animal; D005260:Female; D057898:Hemizygote; D006720:Homozygote; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology* / Q000628:therapy; D009687:Nuclear Proteins / Q000235:genetics*; D015513:Oncogene Proteins / Q000235:genetics*; D017422:Sequence Analysis, DNA; D019076:Transgenes / Q000235:genetics; D014463:Ultrasonography
chemical_list: C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins