A Novel Role for MiR-520a-3p in Regulating EGFR Expression in Colorectal Cancer

Background/Aims: MicroRNAs (miRNAs) have been consistently demonstrated to be involved in colorectal cancer as either tumour oncogenes or tumour suppressors. However, the detailed role of miR-520a-3p in colorectal cancer remains poorly understood. Methods: Quantitative RT-PCR and western blotting assays were used to measure miR-520a-3p and EGFR expression levels in colorectal cancer tissues, respectively. Luciferase reporter assay was employed to validate the direct targeting of EGFR by miR-520a-3p. Cell migration, apoptosis and cell cycle assays were performed to analyse the biological functions of miR-520a-3p and EGFR in colorectal cancer cells. In vivo experiment was performed to analyse the effects of miR-520a-3p and EGFR on the growth of colorectal cancer xenografts in mice. Results: In this study, we found that miR-520a-3p was most likely to target the EGFR 3’-UTR, which was experimentally validated. In addition, we investigated the biological effects of EGFR inhibition by miR-520a-3p both in vitro and In vivo and found that miR-520a-3p could suppress cell migration, promote apoptosis, lead to colorectal cancer cell cycle arrest at the G0/G1 phase, and decelerate tumour growth in xenograft mice, potentially by targeting EGFR. Conclusions: This study highlights a tumour suppressor role for miR-520a-3p in colorectal cancer via the regulation of EGFR expression. Thus, miR-520a-3p may be a novel molecular therapeutic target for colorectal cancer.