MicroRNA Profiles Distinguishing Metastatic from Non-Metastatic Salivary Mucoepidermoid Carcinoma

Background/Objectives: Mucoepidermoid carcinoma (MEC) is the most common malignant tumor of the salivary glands. Metastatic spread occurs in up to 80% of high-grade tumors; however, the mechanisms underlying this process are largely unknown. Large-scale microRNA (miRNA) expression profiling studies of human cancers have demonstrated that dysregulation of miRNA is frequently associated with many cancer types. This study aimed to investigate the miRNA profiles of metastatic and non-metastatic MECs. Methods: Using real-time RT-PCR (qPCR), we analyzed the expression of 377 miRNAs in four non-metastatic MECs, three MECs with lymph node metastasis, three MECs with distant metastasis, and two non-neoplastic human salivary glands. To identify differentially expressed miRNAs, bioinformatics analysis was performed using hierarchical clustering analysis. Results: The miRNA profile discriminated between non-neoplastic and tumor samples and between metastatic and non-metastatic tumors. Twelve miRNAs were differentially expressed between non-neoplastic and non-metastatic MECs. MEC analysis of non-neoplastic and lymph node metastases demonstrated that 10 miRNAs were differentially expressed. In non-neoplastic versus distant metastatic MECs, three miRNAs were differentially expressed: one downregulated and two upregulated. By comparing non-metastatic MECs with lymph node metastatic MECs, we identified 17 upregulated miRNAs. Considering non-metastatic MECs versus distant metastatic MECs, two miRNAs were upregulated. One miRNA was differentially expressed between lymph node metastatic and distant metastatic MECs. Conclusions: Our findings indicated that miRNA profiles may serve as valuable biomarkers for distinguishing the metastatic potential of salivary MECs, warranting further investigation to validate their utility in clinical practice.