Identification of microRNAs involved in the radioresistance of esophageal cancer cells.

Radioresistance is considered as the most important reason for local tumour recurrence. This study investigates the role of miRNAs in radioresistant human esophageal cancer cells. Human miRNA microarray has been used to detect the differential expressed microRNAs between radioresistant esophageal cell line KYSE-150R and the parental cell line KYSE-150. The relative expression of some candidate miRNAs was measured by quantitative real-time PCR (qRT-PCR). Potential mRNA targets were analysed bioinformatically. Significant upregulation of 10 microRNAs and downregulation of 25 microRNAs were detected. The statistical significance of downregulation in hsa-miR-301a, hsa-miR-141 and hsa-miR-18b expression (P < 0.05) were confirmed by qRT-PCR. The correlation of the predicted microRNA target genes to apoptosis (63 genes), cell cycle (67 genes), DNA damage and repair (18 genes) were confirmed by functional annotation. The downregulation of hsa-miR-301a promoted radioresistance in KYSE-150R through the upregulation of wnt1, indicating that wnt/β-catenin signal pathway might be important in radioresistance. In conclusion, a unique set of miRNAs and their expression profiles in radiation resistance have been identified, providing a solid basis for future studies to investigate the target genes of these miRNAs and their function.