RECAPITULATING THE POST-SURGICAL BRAIN MICROENVIRONMENT OF ATYPICAL TERATOID RHABDOID TUMOURS TO IDENTIFY MEMBRANE PROTEINS FOR TARGETED THERAPY

Abstract

Abstract AIMS Atypical Teratoid Rhabdoid Tumours (AT/RT) are rare 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. Decellularised human brain cerebellum aim to recapitulate AT/RT post-surgical brain microenvironments which retain extracellular matrix (ECM) ligands, and where AT/RT plasma membrane proteins are hypothesised to represent viable molecular therapy targets. METHOD AT/RT, astrocyte and human brain cerebellum (decellularised and non-decellularised) membrane protein fractions were extracted and analysed using liquid chromatography-mass spectrometry. Proteomic analysis tools were integrated to identify differential expressed proteins and identify shared correlations. RESULTS Decellularised cerebellar ECM exhibited an enriched membrane proteome relative to total proteome, evidence of complete removal of intracellular components. Furthermore, decellularised and non-decellularised cerebellar tissue expressed comparable levels of membrane proteins and protein networks, indicative of ECM ligand retention. AT/RT and astrocyte KEGG Pathway analysis revealed specific oncology-based pathway expression in membrane protein compared to total protein, reinforcing membrane proteins as more visible therapeutic targets. Between the top 20 expressed proteins, ATP1A1 was the only membrane protein shared exclusively between all AT/RT cells and astrocytes, suggesting a critical 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 molecular subtypes, which may offer candidate ubiquitous therapy targets. Membrane proteins expressed similarly in AT/RT-MYC molecular subtypes include ATP1A1, SLC7A5 and EEF1A1. STRING membrane pathway analysis also identified shared proteins between AT/RT and astrocyte cell populations. CONCLUSION AT/RT membrane protein pathways provide ideal 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 the AT/RT post-surgical microenvironment. Cerebellum decellularisation still permits retention of essential proteins and ligands.