MiR-339-5p Regulates the Growth, Colony Formation and Metastasis of Colorectal Cancer Cells by Targeting PRL-1

MicroRNAs (miRNAs) have been suggested to play a vital role in regulate tumor progression and invasion. However, the expression of miR-339-5p in colorectal cancer and its effects are not known. Here, we report that miR-339-5p is a tumor suppressor by regulating expression of PRL-1. In this study, we showed that downregulated miR-339-5p levels in colorectal cancer tissues and highly invasive CRC cell lines. Furthermore, enhancing the expression of miR-339-5p inhibited CRC cell growth, migration and invasion in vitro and suppressed tumor growth in vivo. We then screened and identified a novel miR-339-5p target, phosphatases of regenerating liver-1 1 (PRL-1), and it was further confirmed by luciferase assay. Overexpression of miR-339-5p would also reduce the expression of PRL-1 mRNA and protein. The reduced PRL-1 expression was associated with low expression of phosphorylated-extracellular signal-regulatedkinase1/2 (p-ERK1/2). Conversely, reduction of miR-339-5p by inhibitors in cells stimulated these phenotypes. In conclusion, our results demonstrate that miR-339-5p functions as a tumor suppressor and plays a role in inhibiting growth and metastasis of CRC cells through targeting PRL-1 and regulating p-ERK1/2. These findings suggest that miR-339-5p may be useful as a new potential therapeutic target for CRC.