HGG-25. IDENTIFYING YB1 AND NPM1 AS PART OF THE MUTANT HISTONE 3 PROTEIN INTERACTOME IN H3 MUTATED PHGG

Abstract

Abstract Paediatric high-grade gliomas (pHGG) are the leading cause of childhood cancer deaths, accounting for over 40% of deaths in the UK. pHGG tumours harbour histone H3 mutations, defining 50% of pHGG cases. Studies show prominent mutations as being H3.3K27M and H3.3G34R/V. Our previous proteomic research on H3 intercatomes, identified unique and common interacting binding partners of H3-G34R and H3-G34V mutant proteins relative to wild type H3. Among these proteins we have focused on YB-1 and Nucleophosmin 1 (NPM1). YB-1, is multifunctional transcription factor and a well-characterised oncogenic protein. NPM1 is a molecular chaperone and frequently overexpressed in cancers. Our aim is to analyse the role of YB-1 and NPM1 in H3 mutated pHGG, in order to identify targeted therapeutic options for these difficult to treat tumours. H3 mutated glioma cell lines, H3 wild type pHGG cells and control cells were cultured and then subjected to comparative immunofluorescence microscopy, and western blot analyses to investigate YB-1 and NPM1 expression. Results showed statistically significant altered protein expression and localisation of YB-1 and NPM1 in H3 mutated pHGG in comparison to wild type and control cells. YB-1 expression was increased in H3 mutated cells and NPM1 showed increased cytoplasmic localization in H3 mutated cells in comparison to H3 WT glioma and control cells. Results of the study support that YB-1 and NPM1 are important interacting proteins in H3G34-mutated pHGGs and can be explored as potential therapeutic targets in H3 mutated pHGG.