Work

IMMU-60. Proteomic Profiling Reveals Enrichment of Chaperone-Associated Regulators in GBM-EVs and Their Potential Role in EV Biogenesis

Year: 2025

Type: article

Abstract: Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults and is characterized by profound local and systemic immune suppression, which undermines the efficacy of immunotherapies. Cell-to-cell communication within the tumor microenvironment and systemically plays a critical role in cancer progression. Extracellular vesicles (EVs) are lipid bilayer-bound structures secreted by all cell types, serving as key mediators of intercellular communication. In cancer, EVs promote tumor progression by enhancing proliferation, pre-metastatic niche formation, angiogenesis, immune evasion, and therapy resistance. Consequently, targeting GBM-specific EV biogenesis pathways represents a promising strategy to counteract tumor-mediated immunosuppression. To identify GBM-specific mechanisms of EV biogenesis, we sought to determine the subcellular compartment most closely associated with GBM-derived EVs. We performed compartment-based proteomic studies on fractionated cells divided into membrane-associated, cytosolic, nuclear soluble, chromatin-associated and cytoskeletal fractions along with their derived EVs using liquid chromatography mass spectrometry. We found that the compartment most closely associated with GBM-EV proteomes was the membrane compartment (r=0.529, p<0.001), suggesting a membrane-associated origin of GBM-EVs. We further performed Gene Ontology (GO) analysis comparing GBM-EV enriched proteins to those from astrocyte-EVs, which revealed enrichment in several exosome-related biological process pathways (FDR<2.62e-24). Notably, we identified a subset of proteins with chaperone-binding functions, including CDC37 and AHSA1, which are co-chaperone proteins that interact with different isoforms of HSP90. Both CDC37 and AHSA1 were significantly enriched in GBM-EVs (log2FC=3.24 and 3.95, p<0.03), suggesting a potential role in cargo sorting or EV release. These findings support that GBM-EVs are predominantly released as exosomes of membrane origin and suggest that chaperone-associated proteins such as CDC37 and AHSA1 may regulate GBM-specific EV biogenesis. Targeting these mechanisms may offer new therapeutic strategies for disrupting tumor-promoting EV signaling in GBM.

Source: Neuro-Oncology

DOI: 10.1093/neuonc/noaf201.0858