Modifiers of Tumor Susceptibility in Murine Neuroblastoma

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Neuroblastoma, a tumor of peripheral neural crest origin, is a common and lethal tumor of childhood. Amplification of the transcription factor MYCN occurs frequently in this tumor, and correlates with advanced disease. We generated a transgenic mouse model for high-risk neuroblastoma by directing expression of a MYCN transgene to the peripheral neural crest, under control of the Tyrosine Hydroxylase (TH) promoter. Genetic analyses identified conserved genetic changes between human and murine tumors, and argue that mice transgenic for TH-MYCN represent an important genetic model for childhood neuroblastoma. We hypothesize that the additional genetic and epigenetic lesions which contribute to neuroblastoma formation in the mouse will be in genes relevant to neuroblastoma in children. The long term objective of this application is to identify genetic and epigenetic changes in murine and human neuroblastoma. Genes identified in this study may reveal novel mechanisms and pathways relevant to human MYCN-amplified neuroblastoma, ultimately leading to novel therapeutic targets. Strains of mice differ in susceptibility to tumors. Mice transgenic for TH-MYCN in strain FVB/N do not develop tumors, nearly all transgenic mice in strain 129/SvJ die of tumors by 4 months of age, and 129/SvJ FVB/N F1 mice show 4% penetrance. These observations suggest that structural or epigenetic changes in germ line modifier genes differ between strains, interact with Mycn, and underlie the differences in susceptibility between strains. These strain-specific differences provide a critical resource to identify secondary genetic and epigenetic events important in both murine and human neuroblastoma. We propose to mobilize a powerful insertional mutagen, the vertebrate Sleeping Beauty (SB) transposon, and to combine use of somatic insertional mutagenesis with comparative genomic hybridization and modifier genetics to identify genes that influence susceptibility to tumors in murine neuroblastoma. Aim 1 uses SB transposon-based insertional mutagenesis to accelerate oncogenic mutations and to increase penetrance of tumors in F1 mice. Aim 2 applies array-based comparative genomic hybridization to characterize copy-number abnormalities in both spontaneous and transposon-induced tumors in F1 mice, to characterize strain-specific methylation patterns, and to identify epigenetic changes in tumors. Aim 3 validates and characterizes candidate genes in-vitro and in-vivo, prioritizing based on the involvement of specific candidate genes in human neuroblastoma.