Human normal breast epithelial cell line MCF 10A (CBP60419) and breast cancer cell lines AU565 (CBP60353), MCF-7 (CBP60380), MDA-MB-157 (CBP60381) and MDA-MB-231 (CBP60382) were all purchased from Cobioer (Nanjing, China). Plasmids including si-NC, si-LINC00461, inhibitor NC, miR-144-3p inhibitor, mimic NC, miR-144-3p mimic, oe-NC, oe-KPNA2 were ordered from GenePharma (Shanghai, China), and the siRNAs were sequenced as below: si-LINC00461: 5′-CTGCAAAGAAGCATAAAATGA-3′; si-NC: 5′-TTCTCCGAACGTG TCACGT-3′.
Before transfection, cells were grown in 6-well plates (3 × 105 cells/well) until the density reached 50%. 250 μL of serum-free Opti-MEM (51985042, Gibco, Gaitherburg, MD, USA) was used to dilute the target plasmids (4 μg) and Lipofectamin 2000 reagent (10 μL; 11668-019, Invitrogen, NY, California, USA), respectively. Thereafter, the dilutions were mixed, and then dripped into cells after 20 min. All cells were maintained in 5% CO2 at 37 °C for 6 h, and cultured for additional 36–48 h with fresh mediums.
Before transfection, cells were grown in 6-well plates (3 × 105 cells/well) until the density reached 50%. 250 μL of serum-free Opti-MEM (51985042, Gibco, Gaitherburg, MD, USA) was used to dilute the target plasmids (4 μg) and Lipofectamin 2000 reagent (10 μL; 11668-019, Invitrogen, NY, California, USA), respectively. Thereafter, the dilutions were mixed, and then dripped into cells after 20 min. All cells were maintained in 5% CO2 at 37 °C for 6 h, and cultured for additional 36–48 h with fresh mediums.