Determining the significance of the N-MYC-WDR5 interaction in neuroblastoma.

项目总结/文摘

PROJECT SUMMARY/ABSTRACT Neuroblastoma (NB) is the most common extracranial solid tumor found in infants, with almost all cases being diagnosed by the age of five. The most severe cases of neuroblastoma are linked to amplification of the N-MYC oncogene, which occurs in ~20% of all NB. N-MYC amplification is associated with ~50% overall survival despite aggressive multimodal therapies, highlighting the need for new targeted therapies to combat this pediatric cancer. N-MYC, like any MYC protein, must be able to recognize and bind chromatin in order to activate its oncogenic potential. This project is built on the premise that an essential co-factor for MYC proteins called WDR5 acts to recruit N-MYC to chromatin at genes that work to maintain neuroblastoma function, and that targeting the N-MYC-WDR5 interaction can serve as a focal point for anti- N-MYC based therapies. Support for this hypothesis comes from published data showing that WDR5 is a conserved regulator of protein synthesis genes across multiple cellular contexts where WDR5 binds and regulates these loci through its so-called “WIN”-site. In addition, the MYC family member, c-MYC, requires WDR5 to bind genes associated with biomass accumulation and translation, and the c-MYC-WDR5 interaction is essential for tumor maintenance in lymphoma mouse models. In an N-MYC amplified NB cell line, preliminary data reveal that targeting the WIN-site of WDR5 using small molecule inhibitors results in a genome-wide decrease in WDR5 binding, with a subsequent loss of N-MYC binding at specific N-MYC- WDR5 co-bound genes. And, importantly, disrupting the N-MYC-WDR5 interaction using genetic mutants impairs the ability of N-MYC to drive anchorage-independent growth, providing evidence that there are essential tumor functions tied to N-MYC that require interaction with WDR5. Together these data provide a solid foundation for the notion that N-MYC requires WDR5 to bind and regulate N-MYC-WDR5 co-bound genes that are important for driving N-MYC specific activities. The goal of this project is to interrogate the N- MYC-WDR5 interaction in N-MYC amplified neuroblastoma cell lines and determine the influence that WDR5 has on N-MYC driven transcriptional processes and neuroblastoma function using genetic and chemical perturbations. Specific Aim 1 will employ genetic and genomic approaches to identify the genes that are bound by N-MYC and WDR5, and determine at which genes the recruitment of N-MYC is dependent on the N-MYC-WDR5 interaction. Specific Aim 2 will combine high-resolution transcriptomic analyses with cellular and in vivo functional assays to challenge the significance of the N-MYC-WDR5 interaction. At the completion of these studies we will have identified the precise genes in which N-MYC binding and transcription is regulated by the N-MYC-WDR5 interaction, and have directly challenged the significance of the N-MYC-WDR5 interactions on multiple facets of NB tumorigenesis.