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Background: MicroRNA (miRNA) array analysis has reported that the expression of miR-593-5p is associated with lymph node metastasis in gastric cancer (GC); however, the function and mechanism of miR-593-5p in GC have not been described yet. miR-593-5p has also not been elucidated widely in other cancers. Methods: miR-593-5p expression was detected by quantitative RT-PCR (qRT-PCR) in human GC tissues and cell lines. Cell proliferation was investigated using CCK-8 assays, cell cycle was detected by flow cytometric method, and cell migration and invasion abilities were evaluated by wound-healing and transwell assays. miR-593-5p-influenced gene expression profiles were detected by total gene expression chip method in MGC-803 cells, and miR-593-5p candidate target genes were predicted using bioinformatics methods. The candidate target gene and downstream of miR-593-5p were determined by qRT-PCR, Western blot, and dual-luciferase reporter assays. The effects of miR-593-5p on the growth and metastasis of GC were evaluated by tumor xenograft experiment in vivo. Results: miR-593-5p was frequently downregulated in GC patients and GC cell lines. miR-593-5p was significantly correlated with tumor size and distant metastasis in GC patients. miR-593-5p inhibited cell proliferation, migration, and invasion and also arrested cell cycle at the G0/G1 phase in SGC-7901 and MGC-803 cells in vitro. miR-593-5p also suppressed tumor growth and metastasis in vivo. miR-593-5p influenced gene expression profile in MGC-803 cells. MST4 was indirectly targeted by miR-593-5p. miR-593-5p also downregulated FAK, MMP12, and JUN protein expression. Conclusion: Our study suggests that miR-593-5p may function as a tumor suppressor in GC through a mechanism that regulates JUN pathway via indirectly targeting the MST4 gene. [ABSTRACT FROM AUTHOR]