Objective To explore the mechanism of microRNA-378a-3p (miR-378a-3p) affecting the development of breast cancer (BC) cells.

Methods The expression of miR-378a-3p in BC cells based on the Cancer Genome Atlas Program database was analyzed. The starBase, miRDB, and miRWalk databases were used to predict the target genes of miR-378a-3p. Double-luciferase reporter experiments were performed to verify the targeted regulation of miR-378a-3p on NUAK family kinase 2 (NUAK2). Real-time fluorescence quantitative PCR and Western blot analyses were used to detect the expression of miR-378a-3p and NUAK2 mRNA and protein in BC cells. Cell proliferation ability was detected through cell-proliferation experiments. Cell scratch assay and invasion assay were used to detect the migration and invasion abilities of cells, respectively. Apoptosis and cell-cycle experiments were conducted to detect cell apoptosis rate and cell cycle distribution.

Results The expression of miR-378a-3p was significantly downregulated in BC cells, and miR-378a-3p overexpression inhibited the proliferation, migration, and invasion of BC cells. miR-378a-3p directly targeted NUAK2 and inhibited the mRNA and protein expression of NUAK2.

Conclusion miR-378a-3p inhibits the proliferation, migration, and invasion of BC cells by targeting NUAK2.