miRNA‐532‐5p functions as an oncogenic microRNA in human gastric cancer by directly targeting RUNX3

Accumulating data reveal that microRNAs are involved in gastric carcinogenesis. To date, no information was reported about the function and regulatory mechanism of miR‐532‐5p in human gastric cancer (GC). Thus, our study aims to determine the role and regulation of miR‐532‐5p in GC. Here, we found that transient and stable overexpression of miR‐532‐5p dramatically increased the potential of colony formation and migration of GC cells, decreased the percentage of cells in G1 phase and cell apoptosis in vitro, and increased the weight of mice lungs and number of lung xenografts in vivo. Gain‐of‐function, loss‐of‐function and luciferase activity assays demonstrated that miR‐532‐5p negatively regulated the expression of RUNX3 and its targets directly. We also found that miR‐532‐5p level was negatively correlated with RUNX3 gene expression in various GC cell lines. Our results indicate that miR‐532‐5p functions as an oncogenic miRNA by promoting cell growth, migration and invasion in human GC cells.