LAUSR

Introduction Meningiomas are the most common primary intracranial brain tumour arising from meningeal tissue. Despite the majority of them displaying benign features, they can cause mild to severe morbidity. The current main therapeutic approach is complete tumour resection commonly with adjunct radiation therapy. However, tumour location can hamper complete resection and chemotherapies are ineffective. In this study we aim to elucidate the pathogenic signature of these tumours and identify novel molecular targets by deciphering the global proteome and phosphoprotein profile of different grades of meningiomas. Material and methods Tumour lysates were collected from grade I, II and III frozen meningioma specimens and three normal healthy human meninges. Phosphoprotein purification was performed using Qiagen® PhosphoProtein Purification Kit. Proteins were separated by SDS-PAGE followed by in-gel tryptic digestion. Extracted peptides were purified and analysed by electrospray ionisation LC-MS/MS. Raw mass spectrometry files were analysed using MaxQuantTM. Expression data were validated by Western blot and immunohistochemistry. In silico functional annotation of expression data was completed using Perseus 1.5.0.31 software suite, Ingenuity Pathway Analysis (IPA®) and DAVID 6.8. Results and discussions We have quantified 3888 proteins and 3074 phosphoproteins across all grades of meningioma and normal meninges. Comparative analysis identified 181 proteins and 338 phosphoproteins to be commonly significantly upregulated (log2 fold-change ≥1.5; p<0.05) among all grades vs. normal meninges, and further identified differential expression profiles between meningioma grades. Expression data was validated on samples analysed by MS and on an additional cohort of meningiomas for upregulated proteins including SET, EGFR, SRSF1, CKAP4 and HK2; and phosphoproteins including AKT1, AKT2 and RB1. Gene Ontology revealed commonly upregulated proteins to be enriched in terms including RNA helicase activity, whilst phosphoproteins were enriched in the phosphoprotein associated terms of signal complex assembly, Rho guanyl-nucleotide exchange factor activity and EGFR signalling. Conclusion In summary, we performed a comprehensive quantitative proteomic analysis from meningioma tissue of all WHO grades compared to healthy meninges and have identified several potential candidates that may hold therapeutic potential for targeted treatment of these tumours.