BACKGROUND/AIM
DNA methylation is a common epigenetic change in cancer. However, microRNA (miRNA) regulation by epigenetic alteration, especially CpG island hypermethylation, remains poorly understood in esophageal squamous cell carcinoma (ESCC).
MATERIALS AND METHODS
miRNAs which were up-regulated after de-methylation with 5-aza-2'-deoxycytidine (5-AZA) were analyzed using the Human miFinder 384HC miScript miRNA PCR Array. The DNA methylation level was evaluated by bisulfite-pyrosequencing assay.
RESULTS
In two of the cell lines, 20 miRNAs, including miR-145-5p, were found to be up-regulated by more than three-fold after 5-AZA treatment. The miRNA-145 promoter was significantly more hypermethylated in the cancer tissues than in matched normal adjacent esophageal epithelial mucosa (p=0.0042; paired t-test). Moreover, the miRNA-145-5p expression levels were significantly lower in cancerous tissues (p=0.0024).
CONCLUSION
miRNA-145 expression in ESCC seems to be regulated by hypermethylation of the miRNA-145 promoter region.