[Overexpression of miR-593-5p inhibits migration, invasion and proliferation and promotes apoptosis of gastric cancer cells by targeting PLK1].

[OBJECTIVES] To explore the role of miR-593-5p targeting Polo-like kinase 1 (PLK1) in regulating biological behaviors of human gastric cancer (GC) cells.

[METHODS] Four GC cell lines (MGC-803, AGS, HGC-27, and MKN-45) and normal human gastric mucosal epithelial GES-1 cells were examined for miR-593-5p and PLK1 expressions using RT-PCR, and MGC-803 cells with the lowest miR-593-5p expression and MKN-45 with highest miR-593-5p expression were selected for subsequent experiments. TargetScan7.2 was used to predict the binding between miR-593-5p and PLK1. MGC-803 cells were transfected with miR-593-5p mimic or mimic NC via liposome, and MKN-45 cells were transfected with miR-593-5p inhibitor or inhibitor NC. The changes in cellular PLK1 protein expression levels were detected using Western blotting, and the changes in biological behaviors of the cells were evaluated using scratch assay, Transwell assay, CCK-8 assay, and flow cytometry.

[RESULTS] Compared with GES-1 cells, the GC cell lines showed significantly downregulated miR-593-5p and upregulated PLK1 expressions. TargetScan7.2 identified binding sites between miR-593-5p and PLK1 3'UTR. In MGC-803 cells, miR-593-5p overexpression caused significant reduction of PLK1 protein expression, inhibited cell migration, invasion, and proliferation, and promoted cell apoptosis. Conversely, miR-593-5p inhibition in MKN-45 cells upregulated PLK1 expression, enhanced cell migration, invasion, and proliferation, reduced cell apoptosis.

[CONCLUSIONS] miR-593-5p overexpression inhibits GC cell migration, invasion, and proliferation, and promotes apoptosis, likely by directly downregulating PLK1, suggesting the role of miR-593-5p as a tumor suppressor in GC and its potential therapeutic relevance.