DataSheet_2_Surfaceome Proteomic of Glioblastoma Revealed Potential Targets for Immunotherapy.xlsx

Glioblastoma (GBM) is the most common and devastating malignant brain tumor in adults. The mortality rate is very high despite different treatments. New therapeutic targets are therefore highly needed. Cell-surface proteins represent attractive targets due to their accessibility, their involvement in essential signaling pathways, and their dysregulated expression in cancer. Moreover, they are potential targets for CAR-based immunotherapy or mRNA vaccine strategies. In this context, we investigated the GBM-associated surfaceome by comparing it to astrocytes cell line surfaceome to identify new specific targets for GBM. For this purpose, biotinylation of cell surface proteins has been carried out in GBM and astrocytes cell lines. Biotinylated proteins were purified on streptavidin beads and analyzed by shotgun proteomics. Cell surface proteins were identified with Cell Surface Proteins Atlas (CSPA) and Gene Ontology enrichment. Among all the surface proteins identified in the different cell lines we have confirmed the expression of 66 of these in patient’s glioblastoma using spatial proteomic guided by MALDI-mass spectrometry. Moreover, 87 surface proteins overexpressed or exclusive in GBM cell lines have been identified. Among these, we found 11 specific potential targets for GBM including 5 mutated proteins such as RELL1, CYBA, EGFR, and MHC I proteins. Matching with drugs and clinical trials databases revealed that 7 proteins were druggable and under evaluation, 3 proteins have no known drug interaction yet and none of them are the mutated form of the identified proteins. Taken together, we discovered potential targets for immune therapy strategies in GBM.

胶质母细胞瘤（Glioblastoma, GBM）是成人中最为常见且致死性极强的恶性脑肿瘤。尽管采取了多种治疗方案，其死亡率仍居高不下，因此亟需发掘全新的治疗靶点。细胞表面蛋白因具有可及性、参与核心信号通路且在癌症中存在表达失调，成为极具吸引力的治疗靶点；此外，它们亦是基于嵌合抗原受体（Chimeric Antigen Receptor, CAR）的免疫疗法或mRNA疫苗策略的潜在作用靶点。在此研究背景下，我们通过对比胶质母细胞瘤与星形胶质细胞系的细胞表面蛋白质组（Surfaceome），旨在鉴定胶质母细胞瘤的新型特异性治疗靶点。为此，我们分别对两类细胞系的细胞表面蛋白进行了生物素标记，随后利用链霉亲和素磁珠纯化生物素标记的蛋白，并通过鸟枪法蛋白质组学（Shotgun Proteomics）开展分析。借助细胞表面蛋白图谱（Cell Surface Proteins Atlas, CSPA）与基因本体（Gene Ontology, GO）富集分析，完成细胞表面蛋白的鉴定。在不同细胞系鉴定得到的所有表面蛋白中，我们采用以基质辅助激光解吸电离质谱（Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry, MALDI-MS）为引导的空间蛋白质组学技术，证实其中66种蛋白在患者胶质母细胞瘤组织中存在表达。此外，我们还鉴定出87种在胶质母细胞瘤细胞系中过表达或特异性表达的表面蛋白。其中，我们筛选得到11种胶质母细胞瘤特异性潜在治疗靶点，包含RELL1、CYBA、EGFR等5种突变蛋白以及主要组织相容性复合体I（Major Histocompatibility Complex I, MHC I）类蛋白。通过与药物及临床试验数据库比对发现，7种蛋白具备可成药性且正处于研发评估阶段，另有3种蛋白尚未发现已知的药物相互作用，且上述靶点均未包含已鉴定的突变蛋白形式。综上，本研究发掘出胶质母细胞瘤免疫治疗策略的潜在靶点。