134 Version 3: Investigating the role of Y-box binding protein 1 in H3-mutated paediatric high-grade gliomas

Abstract Introduction Paediatric-type diffuse high-grade gliomas (pHGGs) are a group of highly aggressive brain tumours representing the major cause of cancer-related mortality in children and adolescents. Advances in molecular profiling have advanced understanding of pHGG, yet therapeutic progress remains stagnant. Our previous proteomic research identified Y-box binding protein 1 (YB1) as a H3-mutant interacting protein. YB1 is an established oncoprotein whose overexpression is associated with poor prognosis and therapeutic resistance across multiple cancers. Here we investigated YB1 localisation and expression and additionally evaluated the therapeutic potential of YB1 inhibition in H3 mutated pHGG and control cell lines. Methods YB1 localization and expression were investigated using two pHGG cell lines, H3- mutant and H3 wild type (WT), alongside two control cell lines (HeLa and cortical astrocytes). Cell extracts were used for quantitative western blotting using anti-YB1 antibody and followed by densitometric analysis using ImageJ. Cell viability assays (MTT) were conducted using the novel YB1 inhibitor SU056 at 1 µM, 2.5 µM, and 5 µM for 48 and 72 hours on these cells. Result YB1 expression in glioma cell lines was greater than control astrocytes. The inhibition assays demonstrated SU056 to alter viability in glioma cell lines, with viability reducing in a dose- and time- dependent manner. Conclusions These results suggest a potential role for YB1 overexpression in pHGG tumorigenesis and implicate YB1 inhibition as a promising therapeutic approach warranting further investigation.