miR-495 and miR-551a inhibit the migration and invasion of human gastric cancer cells by directly interacting with PRL-3

The phosphatase of regenerating liver-3 (PRL-3) gene is associated with metastasis in gastric cancer, and is believed to play a causative role by promoting tumor cell motility, invasion, and metastasis, but little is known of the mechanisms involved. We previously reported that PRL-3 expression is significantly higher in the tissues of primary gastric carcinomas with peritoneal metastasis. In the present study, we found that two microRNAs (miRNAs), miR-495 and miR-551a, predicted to target PRL-3, are downregulated in gastric carcinoma samples. The validation of this interaction between those two miRNAs and PRL-3 was confirmed by western blotting and quantitative real-time PCR (qPCR) in GC cell lines transfected with miR-495 and miR-551a mimics. Furthermore, the migration and invasion of GC cells were significantly inhibited by transfection with miR-495 or -551a mimics, and the mRNA and protein levels of PRL-3 were reduced in cells overexpressing miR-495 or -551a. Collectively, our findings suggest that miR-495 and miR-551a both act as tumor suppressors by targeting the PRL-3 oncogene and inhibiting gastric cancer cell migration and invasion. The findings of this study contribute to current understanding of the functions of miRNA mimics in GC gene therapy. (C) 2012 Elsevier Ireland Ltd. All rights reserved.