Hydrogel-enriched salivary exosomal microRNAs: reliable biomarkers for head and neck squamous cell carcinoma

The diagnosis and post-treatment monitoring of head and neck squamous cell carcinoma (HNSCC) are challenging, highlighting the need for reliable and noninvasive biomarkers. Salivary exosomal microRNAs are promising candidates; however, their clinical utility has been hampered by limitations of conventional isolation methods. To address this gap, we employed a rigorous discovery-validation study design using independent patient cohorts, transitioning from ultracentrifugation in the discovery phase to an advanced, gentle hydrogel-based method for exosome enrichment in the validation phase. Candidate microRNAs were screened using microarray analysis and validated using quantitative real-time polymerase chain reaction. Our multistep screening identified five robustly detectable microRNAs. Among these, salivary exosomal miR-26a-5p has demonstrated a high accuracy in diagnosing HNSCC, particularly oral cavity cancers. Furthermore, post-operative decreases in miR-1290 and miR-4454 levels were strongly associated with favorable clinical outcomes, whereas persistently high or increased levels indicated a high risk of recurrence or poor prognosis. This study validated a panel of salivary exosomal microRNAs as powerful, non-invasive biomarkers, and the use of a novel hydrogel-based enrichment technique enhanced the reliability and clinical applicability of these findings to improve patient-management strategies.