Altered expression of microRNAs (miRNAs) has been shown in many types of malignancies including the head and neck squamous cell carcinoma (HNSCC). Although there are many new and innovative approaches in the treatment of HNSCC, a clear marker of this disease is still missing. Three candidate miRNAs (miR-29c-3p, miR-200b-5p and miR-375-3p) were studied in connection with HNSCC using quantitative real-time PCR expression levels in 42 tissue samples of HNSCC patients and histologically normal tumour-adjacent tissue samples of these patients. Primary HNSCC carcinoma tissues can be distinguished from histologically normal-matched noncancerous tumour-adjacent tissues based on hsa-miR-375-3p expression (sensitivity 87.5 %, specificity 65 %). Additionally, a significant decrease of hsa-miR-200b-5p expression was revealed in tumour-adjacent tissue samples of patients with node positivity. Lower expression of hsa-miR-200b-5p and hsa-miR-29c-3p in HNSCC tumour tissue was associated with higher tumour grade. Consequently, survival analysis was performed. Lower expression of hsa-miR-29c-3p in tumour-adjacent tissue was associated with worse overall and disease-specific survivals. Lower expression of miR-29c-3p in tumourous tissue was associated with worse relapse-free survival. hsa-miR-375-3p seems to be a relatively promising diagnostic marker in HNSCC but is not suitable for prognosis of patients. Furthermore, this study highlighted the importance of histologically normal tumour-adjacent tissue in HNSCC progress (significant decrease of hsa-miR-200b-5p expression in tumour-adjacent tissue of patients with node positivity and low expression of hsa-miR-29c-3p in HNSCC tumour-adjacent tissue associated with worse prognosis).
Keywords: Biomarkers, tumour; Carcinoma, squamous cell of head and neck; Head and neck neoplasms; MicroRNAs; Proportional hazards models; Survival.