Small extracellular vesicles in clinical Cancer research - A quantitative proteomics perspective

'Small extracellular vesicles (sEVs) are nanosized, membrane-enclosed sacs released by diverse cell types. They play a critical role in cell-cell communication through their cargo, which includes a wide range of proteins, lipids, and nucleic acids. Physiologically, sEVs circulate in various body fluids such as blood, urine, and saliva, making them accessible for diagnostic via non-invasive isolation techniques. Recent advances in high-throughput proteomics have significantly enhanced our ability to characterize the protein content of sEVs. Importantly, multiple studies on human fluids have identified specific protein markers across different cancer types, encompassing molecules involved in inflammation, cellular adhesion, immunity, and lipoprotein regulation. Interestingly, some of these proteins are consistently detected across multiple cancer types and sample sources, suggesting the existence of a shared "oncogenic signature" that may be transferred via sEVs. Among body fluids, urine and saliva are particularly promising for easy, non-invasive diagnostics. However, these sample types remain underexplored as compared to the serum, leaving substantial opportunities for future research. Taken together, these findings position sEVs as a powerful tool with significant potential for advancing precision cancer care. SIGNIFICANCE: Living cells release nanosized membrane-enclosed vesicles called small extracellular vesicles (sEVs) into the extracellular environment. sEVs contain protein cargo molecules that critically take part in cell-cell communications. Quantitative proteomics identified potential sEV associated biomarkers for early cancer diagnosis and therapy. sEV Proteins associated with cell adhesion and inflammation, lipoproteins and immunoglobulins are potential molecules that were majorly identified. Interestingly, some of these proteins such as APOA4, SAA4, ITIH4, SERPINC1 and VWF were consistently identified across multiple cancer types and sample sources, highlighting their potential as future biomarkers.