RESUMO
BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common tumor worldwide and is histologically heterogeneous. Studies have demonstrated the presence of stem cell markers in HNSCC, and microRNAs (miRNAs) have emerged as powerful regulators of differentiation, controlling the self-renewal of stem cells. miRNAs are non-coding RNA molecules that regulate gene expression post-transcriptionally. Many miRNAs have been described as regulators of stem cells in different types of cancer. METHODS: We have analyzed the expression of let-7a, miR-34, miR-125b, miR-138, miR-145, miR-183, miR-200b, miR-203, and miR-205 by real-time RT-PCR (qPCR), in 35 oral cavity and oropharynx squamous cell carcinoma (SCC) samples and 10 non-neoplastic oral mucosa controls, to determine possible associations between the expression of these miRNAs and clinical and pathological features of these tumors. RESULTS: We observed downregulation of miR-200b and miR-203 in 60.0% and 71.4% of the samples, respectively. Upregulation of miR-138 and miR-183 was observed in 50.0% of the samples. Downregulation of let-7a was associated with perineural invasion. Upregulation of miR-138, miRNA-145, and miR-205 was associated with advanced tumor stages, vascular invasion, and lymph node metastasis, respectively. CONCLUSIONS: Our study provides evidence of the expression of miRNAs associated with stem cell regulation in oral cavity and oropharynx SCC and the association of these miRNAs with clinical and pathological features of these tumors.