MEMBRANE PROTEOMICS TO ELUCIDATE THE BASIS OF WIRELESS BIOELECTRONIC-INDUCED CELL DEATH IN GLIOBLASTOMAS

Abstract AIMS Isocitrate dehydrogenase wild-type glioblastomas (GBMs) are the most common form of brain cancer with a median survival of approximately 15 months, with less than 5% of patients surviving 5 years after diagnosis. GBMs are incurable with recurrence being inevitable. Therefore, there is a need for more effective and targeted treatments to prevent this. Stimulation of GBM cells with a wirelessly-activated electric field (EF) has been shown by us to selectively induce apoptosis, sparing cortical astrocytes. The aim of this work was to elucidate candidate membrane and cellular proteins responsible for this phenotype, by analysing differential proteomic profiles in the absence/presence of EF. METHODS Human cortical astrocytes and glioma invasive margin (GIN) cells were cultured in 2D and both cellular and membrane proteins extracted. Differentially expressed proteins were identified using liquid-chromatography- mass spectrometry (LC-MS)-based proteomics. RESULTS LC-MS revealed protein expression differed between each of three GIN cell lines (GIN8, GIN28 and GIN31), and between astrocytes. In all three GIN cell lines, 18 membrane proteins were identified as significantly upregu- lated. Through comparison of these 18 membrane proteins with pathological data, three of these proteins con- ferred a significant negative correlation on prognosis when upregulated in GBMs. These proteins were DYSF, ROBO1 and LOXL1, with LOXL1 associated with the most significant effect. CONCLUSION This demonstrates that membrane proteins are often dysregulated in GBMs making them ideal potential ther- apeutic targets, due to exposure on the cell surface (i.e., druggable). Using similar methodology, we aim to investigate how treatment with EF alters these membrane proteins to better understand the genetic basis of how apoptosis is selectively induced in GBM cells and conversely how astrocytes are relatively resistant. Eluci- dation of this mechanism would generate insight on potential therapeutics which may potentiate the effects of the EF, for which we hypothesise that DYSF, ROBO1 and LOXL1 are candidates.