miR-25 is upregulated before the occurrence of esophageal squamous cell carcinoma

MicroRNAs (miRNAs) are potential biomarkers for cancer detection including esophageal squamous cell carcinoma (ESCC); however, little is known about their expression profile and diagnostic impact in esophageal squamous cell intraepithelial neoplasia, the pathological precancerous lesion of ESCC. In this study, we examined the expression levels of eight miRNAs that were reported to be deregulated in ESCC, including miR-25, let-7a, miR-100, miR-133a, miR-223, miR-375, miR-483-5p and miR-1322, in 30 pairs of esophageal squamous cell neoplasia lesion tissues and corresponding adjacent normal tissues using quantitative real-time PCR (qRT-PCR). Differential expression of miRNAs was further examined by in situ hybridization. Furthermore, the deregulated miRNAs were also measured in serum and serum exosome samples of these patients. miR-25, an oncomir that had been reported to be upregulated in ESCC tissues, were found to be overexpressed in esophageal squamous cell intraepithelial neoplasia lesions (66.7%, 20/30) compared to adjacent normal tissues (P < 0.05), while the other seven miRNAs did not show a significant difference between the lesions and controls. The miR-25 signal was stronger in lesion tissues than in normal tissues according to in situ hybridization. The concentrations of miR-25 in both serum and exosome samples of patients were not significantly different from those of healthy individuals. These findings suggested that the overexpression of miR-25 in esophageal squamous cell intraepithelial neoplasia lesions might be a promising early biomarker candidate for the prediction of ESCC.