Mir 140 3p mimic

miR-140-3p mimic (5′-UACCACAGGGUAGAACCACGG-3′), inhibitor (5′-CCGUGGUUCUACCCUGUGGUA-3′), and their corresponding negative controls (NC-mimic, 5′-GCAAGAGACAAGCGCUUAGCC-3′ and NC-inhibitor, 5′-GGUCCUGAUUCGUGCUACUCG-3′) were synthesized by Guangzhou Ribobio Co., Ltd. (Guangzhou, China). Small interfering RNA targeting TRIM28 (si-TRIM28, 5′-GACCAAACCTGTGCTTATGTT-3′) and NC (5′-GTTCTCCGAACGTGTCACGT-3′) was synthesized by Shanghai GenePharma Co., Ltd. (Shanghai, China). A total of 2,000 cells (MCF-7 and MDA-MB-453) were seeded into 6-well plate and incubated until they reached 70–80% confluency. Transfection was conducted using Lipofectamine^® 2000 (Invitrogen; Thermo Fisher Scientific, Inc., Waltham, MA, USA) with 50 nM miRNA or 50 nM siRNA into MCF-7 and MDA-MB-453 cells, according to the manufacturer's protocols. After 48 h of transfection, cells were collected for following assays.

The miR-140-3p mimic, miR-140-3p inhibitor, and negative control oligo were purchased from Ribo-Bio (Guangzhou, China). Oligo transfection was performed using the reagent RNAiMax (Invitrogen, USA) according to the manufacturer's instructions.