Development of a novel dual inhibitor for treatment of MYCN-amplified neuroblastoma - PROJECT SUMMARY/ABSTRACT Neuroblastoma is the most common extracranial tumor occurring in childhood with the majority of patients being under five years old. High-risk cases of neuroblastoma are associated with amplification of the MYCN oncogene, an event that occurs in ~50% of all high-risk situations and results in poor overall survival despite aggressive multimodal therapies. MYCN encodes the transcription factor N-MYC, which like any MYC protein functions to regulate expression of thousands of genes involved in multiple biological processes. The ability of any MYC protein to drive cancerous gene expression is dependent on the cofactor interactions that MYC makes to sculpt the transcriptome towards tumor formation. Because direct targeting of MYC proteins has proved to be challenging, an alternative approach to inhibit MYC has arose that is based on identifying important MYC cofactors that have surfaces amenable to small molecule inhibition and focusing drug discovery efforts on those cofactors as a means to disable MYC function. Two N-MYC cofactors that are viable candidates for this approach in MYCN-amplified neuroblastoma are WDR5 and G9a. In these cancers, my group pioneered the idea to inhibit N-MYC function through our studies on WDR5. The work of our lab and others support the essential role of WDR5 as a direct N-MYC cofactor that facilitates recruitment of N-MYC to promoters of genes involved in the ability of N-MYC to push abnormal cell growth and division. Also in MYCN-amplified NB, evidence indicates that G9a is a N-MYC cofactor that is recruited by N-MYC to enhancers of genes that contribute to cell differentiation, effectively repressing expression of differentiation genes and thus permitting N-MYC to drive an oncogenic gene expression program. While development of small molecules that target either WDR5 or G9a alone have continued to advance, resistance mechanisms and drug development issues associated with single-agent treatment are already surfacing. The premise of this project is based on the idea that to disable a larger portion of N-MYC function —and overcome any drug development issues—these cofactors should be inhibited together and if possible through a single molecule. Therefore, the goal of this project is to move WDR5 and G9a into the focus of novel drug discovery efforts through a combination of chromatin-focused studies and pursuit of dual inhibitors that can target both proteins. Specific Aim 1 will employ genetic, genomic, and chemical biology approaches to identify the genes that are bound and regulated by N-MYC, WDR5, G9a, and determine how combined inhibition impacts N-MYC-dependent transcription. Specific Aim 2 will challenge the notion that dual inhibition is possible by using computationally-driven drug discovery to identify and screen potential chemicals that can inhibit WDR5 and G9a together. At the completion of these studies we will have comprehensively detailed the role of WDR5 and G9a in MYCN-amplified neuroblastoma and evaluated dual inhibition of WDR5 and G9a as a potential therapeutic strategy to block N-MYC function.
