Abstract

Background
Glioblastoma (GBM) is an aggressive brain tumour characterised by rapid growth and infiltration. New therapies are desperately needed to improve GBM patient outcomes. Intra-tumoural heterogeneity is a common driver of failure for novel GBM treatments, and many preclinical studies rely on cell lines established from the tumour core. As a result, they fail to characterise the infiltrative tumour cells which remain post-surgery and ultimately drive tumour recurrence.

Methods
This study characterises the membrane proteome of 3 patient-derived GBM cell lines isolated from the tumour invasive margin (GIN8, GIN28, and GIN31), which is a proxy for residual disease post-surgery. We combined plasma membrane protein analysis with total protein analysis using liquid chromatography-mass spectrometry to uncover therapeutic targets most amenable for drug repurposing. Molecular docking analysis predicted specific binding pockets on the surface of key membrane proteins against which the top 10 approved drug candidates were screened based on their binding energy scores.

Results
Membrane proteins such as EDIL3, DYSF, ROBO1, SERPINE2, LOXL1 and CD70 were consistently significantly upregulated across GBM cell lines relative to healthy astrocyte controls, indicating potential functional roles in GBM progression. Molecular docking identified nilotinib (targeting LOXL1) and darifenacin (targeting SH3KBP1) as candidate drugs that can bind to identified membrane proteins. Nilotinib and darifenacin produced average IC50 values of 8.45 µM and 46.77 µM, respectively, in cell viability assays against GIN cell lines.

Conclusions
These findings suggest that targeting membrane proteins offers promise for developing effective GBM therapies predicated on the most prognostically-relevant intra-tumour region.