A method is provided for decreasing at least one of the proliferation and the migration of a cancer cell comprising contacting a cancer cell with an effective amount of a pharmaceutically acceptable composition comprising a microRNA (miRNA) having a nucleotide sequence having at least 80% sequence similarity to the nucleotide sequence of miR-3189-3p derived from the miR-3189 mitron of the Growth Differentiation Factor 15 (GDF15) gene. The methods and compositions are advantageous for inhibiting proliferation and migration of, but not limited to, glioblastoma cells, melanoma cells, and breast cancer cells.