Meta-signature guided investigation of miRNA candidates as potential biomarkers of oral cancer.

OBJECTIVES: This study aimed to experimentally validate dysregulated expression of miRNA candidates selected through updated meta-analysis of most commonly deregulated miRNAs in oral cancer and to explore their diagnostic and prognostic potential. MATERIALS AND METHODS: Five miRNAs (miR-31-3p, miR-135b-5p, miR-18a-5p, miR-30a-5p and miR-139-5p) from updated meta-signature were selected for validation by qRT-PCR method in 35 oral cancer clinical specimens and adjacent non-cancerous tissue. RESULTS: Updated meta-analysis has identified 13 most commonly deregulated miRNAs in oral cancer. Seven miRNAs were consistently up-regulated (miR-21-5p, miR-31-3p, miR-135b-5p, miR-31-5p, miR-424-5p, miR-18a-5p and miR-21-3p), while five were down-regulated (miR-139-5p, miR-30a-3p, miR-375-3p, miR-376c-3p and miR-30a-5p). Increased expression of miR-31-3p and miR-135b-5p, and decreased expression of miR-139-5p and miR-30a-5p were confirmed in oral cancer compared to adjacent non-cancerous tissue. A three miRNAs combination (miR-31-3p, miR-139-5p and miR-30a-5p) gave the most promising diagnostic potential for discriminating oral cancer from non-cancerous tissue (AUC: 0.780 [95% CI: 0.673-0.886], p < 0.0005, sensitivity 94.3%, specificity 51.4%). High expression of miR-135b-5p, miR-18a-5p and miR-30a-5p was associated with poor survival (p = 0.003, p = 0.048, p = 0.016 respectively). CONCLUSION: miR-31-3p, miR-139-5p and miR-30a-5p panel was confirmed as a potential diagnostic biomarker when distinguishing oral cancer from non-cancerous tissue. miR-135b-5p, miR-18a-5p and miR-30a-5p might serve as potential biomarkers of poor survival of oral cancer patients.