Downregulated miR-524-5p Participates in the Tumor Microenvironment of Ameloblastoma by Targeting the Interleukin-33 (IL-33)/Suppression of Tumorigenicity 2 (ST2) Axis.

BACKGROUND Ameloblastoma (AB) is a common odontogenic epithelial tumor, with locally invasive behavior and high recurrence. In this study, we hypothesized that miR-524-5p could be involved in the tumor microenvironment by targeting interleukin-33 (IL-33)/suppression of tumorigenicity 2 (ST2) in AB. MATERIAL AND METHODS The microRNA (miRNA) expression profile of AB tissues and normal oral mucosa tissues (NOM; 6 paired samples) was analyzed. The miRNAs with fold change ≥2 and P<0.05 were considered to be differentially expressed. Among them, downregulated miR-524-5p was verified by real-time qPCR. Potential targets of miR-524-5p were predicted by bioinformatics analysis. The expression levels of target genes were detected using real-time qPCR and Western blot, respectively. Immunohistochemistry analysis of target genes was performed, and we also assessed the correlation between miR-524-5p and its target. RESULTS Microarray analysis results first indicated miR-524-5p is a downregulated miRNA in AB tissues. Real-time qPCR results confirmed the expression pattern of miR-524-5p in AB tissues. Moreover, IL-33 and its receptor ST2 were significantly overexpressed. As shown in immunohistochemistry results, IL-33 was positively expressed in lymphocytes and plasma cells, suggesting that IL-33/ST2 participates in tumor immune responses in the tumor microenvironment. Correlation analysis suggested that miR-524-5p expression was negatively correlated with IL-33/ST2. CONCLUSIONS Our findings reveal that downregulated miR-524-5p can participate in the tumor microenvironment of AB by targeting the IL-33/ST2 axis.