Better understanding of GBM signalling networks in-vivo would help develop more physiologically relevant ex vivo models to support therapeutic discovery. A "functional proteomics" screen was undertaken to measure the specific activity of a set of protein kinases in a two-step cell-free biochemical assay to define dominant kinase activities to identify potentially novel drug targets that may have been overlooked in studies interrogating GBM-derived cell lines. A dominant kinase activity derived from the tumour tissue, but not patient-derived GBM stem-like cell lines, was Bruton tyrosine kinase (BTK). We demonstrate that BTK is expressed in more than one cell type within GBM tissue; SOX2-positive cells, CD163-positive cells, CD68-positive cells, and an unidentified cell population which is SOX2-negative CD163-negative and/or CD68-negative. The data provide a strategy to better mimic GBM tissue ex vivo by reconstituting more physiologically heterogeneous cell co-culture models including BTK-positive/negative cancer and immune cells. These data also have implications for the design and/or interpretation of emerging clinical trials using BTK inhibitors because BTK expression within GBM tissue was linked to longer patient survival.

Cardiff University Hospital Cellular Pathology Cardiff UK

Department of Basic Medical Sciences Faculty of Medicine The Hashemite University Zarqa Jordan

Department of Neuropathology Western General Hospital Edinburgh UK

Institute of Genetics and Cancer University of Edinburgh Edinburgh UK

International Centre for Cancer Vaccine Science University of Gdansk Gdansk Poland

Pamgene International BV 's Hertogenbosch Netherlands

Research Centre for Applied Molecular Oncology Masaryk Memorial Cancer Institute Brno Czech Republic

Translational Neurosurgery Centre for Clinical Brain Sciences University of Edinburgh Edinburgh UK

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