Hannah Park - US grants

PROJECT SUMMARY / ABSTRACT Brain tumors account for 20% of all childhood cancers and more deaths than any other pediatric cancer. Gliomas are the most common type of CNS tumor in children (52.9%). Though current therapy is aggressive, it offers little salvage for the patient?s quality of life and survival. The 5-year survival for high-grade pediatric glioma after surgery, chemotherapy and radiation is 15-35%. Even in the case where the patient survives, the therapeutic regimen degrades cognitive functions central to individuality. It is imperative to explore novel mechanisms and targets for this disease. We have recently shown that Etv5 function is necessary for tumor formation using a novel mouse model of pediatric glioma. However, the specific mechanisms which regulate Etv5 function in glioma remain unknown. Our preliminary data indicates a need for Etv5 activation by post-translational modifications (PTM) in pediatric glioma cells. There is evidence in literature that phosphorylation and acetylation of Etv5 protein on specific amino acid sites significantly increase transactivation potency. Additionally, we have evidence that Etv5 is promoting the oligodendrocyte precursor cell (OPC) fate in tumor cells. High-grade pediatric gliomas are often comprised of dense populations of OPCs and converging evidence suggests that OPCs are the cell-of-origin. We hypothesize that ETV5 is hyperactivated in pediatric glioma by post-translational modifications resulting in the induction of OPC genes OLIG2, NKX2-2 and CCND1. We propose to carry out this work in two parts. In Aim 1, we will identify PTMs occurring on ETV5 in patient- derived pediatric glioma cells. I will do so by isolating ETV5 and performing mass spectrometry analysis to determine modifications on specific residues. I will functionally validate these findings by testing the effects of verified PTMs on tumor burden and survival. In Aim 2, we will interrogate the genomic targets of ETV5 in patient-derived cells using ChIP-seq analysis. From this dataset, we will be able to determine if OPC cell-fate genes are regulated by binding or ETV5 to their enhancer/promoter regions. We can further validate these findings by identifying differential gene expression in ETV5 knockdown models using RNA-seq. Lastly, I will functionally validate our findings by knocking down Etv5 targets in our mouse model of glioma to determine effects on survival. The findings resulting from these experiments can elucidate novel therapeutic targets to improve current treatment regimens.