BACKGROUND: Gastric cancer (GC) is a leading cause of cancer-related death. MicroRNAs (miRNAs or miRs) play a crucial role in the pathology of GC, including cell proliferation, invasion, and metastasis. In this study, genes targeted by miR-155-5p were predicted using bioinformatic tools. We found that the expression of miR-155-5p in GC cell lines differed relative to the expression of F-box protein 11 (), which is involved in the regulation of cellular processes. This study sought to examine the function of miR-155-5p and the precise mechanism underlying its regulatory function in modulating proliferation and apoptosis in GC. METHODS: The luciferase reporter assay results showed that miR-155-5p bound directly to the three prime untranslated region (3'-UTR) of , which further downregulated expression. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western-blot analyses confirmed that miR-155-5p negatively regulated the messenger RNA (mRNA) and protein expression of . The effects of on cell proliferation and apoptosis in GC cell lines was further examined using Cell Counting Kit-8 (CCK-8) and flow cytometry. RESULTS: We found that promoted proliferation and decreased apoptosis in GC cells. Conversely, rescue experiments showed that the knockdown of limited the effects of miR-155-5p on the proliferation and apoptosis of GC cells, providing further evidence that is a functional target of miR-155-5p. Further, the overexpression of miR-155-5p inhibited cell growth via the targeted inhibition of that regulated mammalian target of rapamycin (mTOR) signaling pathway in the GC cells. CONCLUSIONS: Overall, these results showed that miR-155-5p may serve as a tumor suppressor in GC and that the miR-155-5p/ axis regulates tumor progression via the mTOR signaling pathway. Consequently, our findings may lead to the development a novel treatment strategy for GC.