Atrt-02. Recapitulating the Post-Surgical Brain Microenvironment of Atypical Teratoid Rhabdoid Tumours to Identify Membrane Protein Candidates for Targeted Therapy

Abstract BACKGROUND Atypical Teratoid Rhabdoid Tumours – (AT/RT) are rare and aggressive tumours primarily arising in the hind brain of children under three, conferring median survival of 12 months. Surgery remains the only standard treatment; however tumours recur from post-surgical residual disease. The utilisation of PolyEthylene Glycol Diacrylate – (PEGDA) hydrogel and decellularised human brain cerebellum extracellular matrix aim to recapitulate AT/RT post-surgery brain microenvironments, where we hypothesise AT/RT plasma membrane proteins represent viable molecular therapy targets. METHODS AT/RT and astrocyte membrane protein cellular fractions were extracted and analysed using liquid chromatography-mass spectrometry. Proteomic analyses was integrated to identify differentially expressed AT/RT and astrocyte membrane proteins. RESULTS PEGDA and decellularised brain tissue were biocompatible for AT/RT-astrocyte co-cultured spheroid growth. AT/RT and astrocyte KEGG Pathway analysis revealed more specific oncology-based pathway expression in membrane protein than total protein, thus reinforcing membrane proteins as suitable therapeutic targets. Between the top 20 expressed membrane proteins, only ATP1A1 was shared exclusively between all AT/RT cells and astrocytes, suggesting a potential functional role. Membrane proteins showing shared expression when normalised against each AT/RT cell line included ATP1A1, HSPD1, GNA13 and SLC3A2, indicating biological similarities between AT/RT subtypes. Membrane proteins expressed similarly in AT/RT-MYC subtypes include ATP1A1, SLC7A5 and EEF1A1. ATP1A1 network analyses of AT/RT and astrocyte membrane protein pathways displayed strong interactions with ATP1B1, SLC7A5 and SLC3A2, therefore likely to map common expressed shared pathways. CONCLUSIONS AT/RT membrane protein pathways offer novel therapeutic targets directly amenable for drug repurposing. Future work prioritises proteomic analysis utilising 3D AT/RT spheroids and cerebellum brain tissue to maximise accurately recapitulating AT/RT post-surgical microenvironments.