To determine the role of miR-483-3p in the downregulation of METTL3 in breast cancer cells, SUM-1315 and MCF-7 cells transfected with/without miR-483-3p inhibitor were treated with/without metformin, and the mRNA and protein expression of METTL3 were determined. This evidence concerns the gene METTL3 and breast carcinoma.