The Antimicrobial Peptide Merecidin Inhibit the Metastasis of Triple-Negative Breast Cancer by Obstructing EMT via miR-30d-5p/Vimentin

Purpose: To investigate the inhibitory effect of antimicrobial peptide merecidin on triple-negative breast cancer (TNBC) and the mechanism of inhibiting epithelial-mesenchymal transformation (EMT) by regulating miR-30d-5p/vimentin. Methods: TNBC cell lines (MDA-MB-231, MDA-MB-468) were treated with merecidin to assess proliferation, migration, invasion ability, and EMT. Confocal laser localization was used to examine the role of merecidin and TNBC cells. The relationship between merecidin and miR-30d-5p was determined through RT-qPCR and dual-luciferase reporter gene, and the relationship between merecidin and vimentin was verified through pulling down the experiment. The effects of miR-30d-5p on the migration and invasion ability of TNBC cells were confirmed through scratch and transwell experiments. Vimentin levels, tumor volume, shape, size, and weight were observed in the MDA-MB-231 subcutaneous tumor model in nude mice. Results: merecidin inhibited the proliferation, migration, invasion, and EMT of TNBC cells. merecidin was primarily located in the cytoplasm of TNBC cells, and the expression of miR-30d-5p was low in TNBC cells. merecidin significantly up-regulated the expression of miR-30d-5p. miR-30d-5p negatively regulated vimentin. merecidin could bind to vimentin in vitro. miR-30d-5p inhibited the migration and invasion ability of TNBC cells, while vimentin promoted their migration and invasion ability. Down-regulation of miR-30d-5p or overexpression of vimentin partially counteracted the inhibitory effects of merecidin on TNBC cell migration, invasion ability, and EMT. In nude mouse tumor models, merecidin significantly suppressed tumor growth. Conclusion: Merecidin effectively blocks the EMT process and inhibits the migration and invasion of TNBC cells by regulating miR-30d-5p/vimentin.