Abstract
BackgroundThe 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.MethodsWe 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.ResultsDNA 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.ConclusionHemizygous 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.
Highlights
Neuroblastoma is an extracranial childhood tumor of the sympathetic nervous system [1]
To investigate if MYCN by itself can contribute to neuroblast transformation, Weiss et al developed a transgenic mouse model with human MYCN expression targeted to migrating cells of the neural crest, by aid of the tyrosine hydroxylase promotor (THMYCN, [6])
Sequencing of the MYCN transgene No previous study has confirmed that the MYCN transgene integrated into the TH-MYCN mouse genomic DNA corresponds to human MYCN cDNA
Summary
Neuroblastoma is an extracranial childhood tumor of the sympathetic nervous system [1]. It displays a very heterogeneous clinical behavior with some tumors spontaneously regressing, whereas others are incurable despite aggressive treatment. The prevalence of MYCN amplification in neuroblastoma patients is. The TH-MYCN mice develop neuroblastoma-like tumors, due to a deficient process of neural crest cell deletion during early life, demonstrating that high MYCN expression can initiate tumorigenesis [6,7]. 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
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