Identification of Glioblastoma Cell Surface Proteins and Assessment of Their Expression Across Patient-Derived Stem-Like Cell Cultures.

Glioblastoma (GBM) is the most common primary brain cancer in adults and remains fatal, with a median survival of a few months. There is an urgent need to develop novel therapeutic strategies against this aggressive malignancy. Modern cancer research increasingly focuses on personalized therapies tailored toward unique molecular features of each tumor or patient. In this context, cell surface proteins (CSPs) represent an attractive class of therapeutic targets due to their accessibility and central roles in physiological and pathological processes, making them among the most targeted proteins in current drug development. In this study, promising CSPs were identified through an untargeted proteomics approach using high-resolution mass spectrometry on patient-derived GBM stem-like cell (GSC) cultures, complemented by RNA-seq data and computational database analyses. From this primary discovery, five CSPs, namely PTK7, PTPRZ1, OSMR, CSPG4, and IGDCC4, were selected for detailed investigation. A targeted UHPLC-multiple reaction monitoring (MRM) method was developed and optimized to assess their expression and evaluate their abundance variations across different GSC cultures and cell passage levels. Beyond confirming these CSPs as potential therapeutic targets in GBM, our study demonstrates the value of three-dimensional GSC cultures as robust models for biomarker research and target assessment.