Saliva-derived Exosomes as Potential New Diagnostic Biomarkers for Head and Neck Cancer

 

Introduction We investigated the cargo and functional profile of saliva-derived exosomes from head and neck squamous cell carcinoma (HNSCC) patients and their potential as non-invasive biomarkers for disease detection.

Methods Exosomes were isolated from saliva of 21 HNSCC patients and 12 healthy donors (HD) by ultracentrifugation. Exosomal surface protein levels and tumor antigens were measured by bead-based flow cytometry using CD63-capture. Alteration of CD8+ and CD4+ T cell activity was investigated upon co-incubation with exosomes by flow cytometry (CD69 expression, CFSE assay). Exosomal adenosine production was measured by mass spectrometry after co-incubation with exogenous ATP. miRNA profiling of saliva-derived exosomes was performed using the nCounter​ SPRINT system.

Results Saliva-derived, CD63-captured exosomes from HNSCC patients carried high amounts of PDL1 and CD39. Moreover, saliva was rich in tumor-derived CD44v3+ exosomes and poor in haematopoietic-derived CD45+ exosomes compared to plasma. CD8+ T cell activity and proliferation of CD4+ T cells were not affected by saliva-derived exosomes. However, saliva-derived exosomes produced high levels of immunosuppressive adenosine. 62 HD- and 31 HNSCC-exclusive miRNAs were identified. Samples were grouped in “Healthy” and “Cancer” based on their saliva-derived exosomal miRNA profile, which was found to be involved in RAS/MAPK, NF-κB complex, Smad2/3, and IFN-α signaling.

Conclusion  Saliva-derived exosomes from HNSCC patients were enriched in tumor-derived exosomes. Surface values of CD44v3, PDL1 and CD39 on CD63-captured exosomes, adenosine production and the miRNA cargo of saliva-derived exosomes emerged as discriminators of disease activity and emphasized their potential as liquid biomarkers for HNSCC.

Deutsche Forschungsgemeinschaft (DFG) & Brigitte und Dr. Konstanze Wegener-Stiftung

Publication History

Article published online:
12 May 2023

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