MiR-122-5p inhibits cell migration and invasion in gastric cancer by down-regulating <italic>DUSP4</italic>.

<bold>Objective</bold>: To explore the relationship between miR-122-5p and <italic>DUSP4</italic> and their effects on gastric cancer (GC) cell mobility and invasiveness. <bold>Methods</bold>: Abnormally expressed miRNAs and mRNAs were analyzed using microarrays. The miR-122-5p and <italic>DUSP4</italic> mRNA expression levels in GC tissues and cells were determined by RT-qPCR. The target relationship between miR-122-5p and <italic>DUSP4</italic> was validated by dual luciferase reporter assay. GC cell mobility and invasiveness were respectively observed by wound healing assay and transwell invasion assay. Western blot and immunohistochemistry were used for detection of the expressions of DUSP4 protein and MMP2 and MMP9 proteins related to cell invasion and migration. The migration and invasion abilities of gastric cancer cells in <italic>vivo</italic> were evaluated according to the number of lung metastatic nodules in mice. <bold>Results</bold>: The expression of miR-122-5p in GC tissues and cells was significantly down-regulated, whereas <italic>DUSP4</italic> expression was up-regulated. Bioinformatics prediction strategies and dual luciferase reporter assay verified the binding sites of miR-122-5p on 3′UTR of <italic>DUSP4</italic> and the target relationship between miR-122-5p and <italic>DUSP4</italic>. Overexpression of miR-122-5p and knockdown of <italic>DUSP4</italic> in BGC-823 cells observantly suppressed GC cell mobility and invasiveness, whereas downregulation of miR-122-5p expression promoted cell metastasis. MiR-122-5p inhibited GC cell mobility and invasiveness and pulmonary tumor metastasis via downregulation of <italic>DUSP4</italic>. <bold>Conclusion</bold>: MiR-122-5p restrained migration and invasion abilities of GC cells by repressing <italic>DUSP4</italic>. [ABSTRACT FROM AUTHOR]