Serum and adipose tissue-derived extracellular vesicles as biomarker reservoirs in oesophageal adenocarcinoma.

Oesophageal adenocarcinoma (OAC) is a highly aggressive malignancy with poor survival rates and rising global incidence. Despite research advances, no validated liquid biopsy biomarkers currently exist for OAC. Extracellular vesicles (EV), due to their role in intercellular communication and ability to carry molecular cargo, represent a promising source of diagnostic and prognostic biomarkers. This study explores the proteomic profiles of EV-enriched preparations derived from serum and adipose-conditioned media (ACM) of OAC patients and non-cancer controls. EV-enriched preparations were isolated using size exclusion chromatography and analysed via label-free liquid chromatography-mass spectrometry. Bioinformatic analysis included principal component analysis and pathway analysis. Kaplan-Meier survival analysis using public datasets evaluated the prognostic relevance of candidate EV proteins. Proteomic profiling identified 65 differentially expressed proteins in serum-derived EV-enriched preparations from OAC patients, enriched in angiogenesis and migration pathways. In adipose tissue-derived EV-enriched preparations, 680 proteins were differentially expressed in OAC patients, with 118 altered between people with obesity and people without obesity. Comparative analysis revealed six consistently upregulated proteins in both serum and adipose-derived EV-enriched preparations: MYL6, VCP, HSP90AB1, CLTC, CCT7, and TCP1. Of these, HSP90AB1, CCT7, and TCP1 were significantly associated with poorer overall survival. These results highlight the role of EV-enriched proteins in tumour progression and immune modulation. This study offers novel biomarker candidates for OAC diagnosis and prognosis, especially in the context of obesity. The identification of clinically relevant proteomic signatures supports the potential of EV-based liquid biopsies for non-invasive disease monitoring and personalised therapeutic strategies in OAC.