114 Blood-borne exosomes as biomarkers in head and neck squamous cell carcinoma (HNSCC)

The strongest risk factors for developing HNSCC are human papillomavirus infection and alcohol/tobacco use. The latter gives rise to a clinically aggressive tumor with a poor prognosis, creating an urgent need for effective screening strategies. Exosomes, or small extracellular vesicles (sEV), and their content are emerging as potential cancer biomarkers. Here, CD9/63/81 positive sEV were isolated from circulating plasma of HNSCC patients and healthy volunteers by immunoaffinity purification and characterized by Western blot and Nanoparticle Tracking Analysis. sEV were subjected to Luminex Multiplex profiling of 12 well-established cancer-specific antigens. Several known cancer biomarkers were detected at high levels on the surface of HPV(-) HNSCC sEV, including CA125, ß-HCG, and HE4, of which HE4 was confirmed by Western blotting. Interestingly, HE4 is a protease inhibitor that may serve to protect sEV from degradation. miRNet target analysis revealed that several miRNAs target HE4, such as miR-146a-5p. KEGG pathway analysis determined that these miRNAs had the highest number of shared targets in pathways in cancer. Additional GO:BP pathway analysis showed that these miRNAs also had numerous shared targets in regulation of DNA binding. qPCR and miRNAseq of blood-borne sEV showed low levels of miR-146a in HPV(-) HNSCC. Collectively, this data demonstrates a correlation between HE4, miR-146a, and the aggressiveness of HPV(-) HNSCC. These combined studies suggest sEV and their components, including HE4, could be a source of potential cancer biomarkers for HNSCC that could provide improvements in diagnosis and treatment.