Mb 231

The human breast cancer cell lines MB-231 and MB-468 were obtained from the Cell Bank of the Chinese Academy of Sciences (Shanghai, China). Cells were cultured in a 5% CO₂ atmosphere at 37°C with Leibovitz's L-15 (Thermo Fisher) medium supplemented with 10% fetal bovine serum (Gibco), 100 U/ml penicillin, and 100 μg/ml streptomycin (Gibco). Hypoxic conditions were achieved by placing the cells in a 1% O₂, 94% N₂, and 5% CO₂ multistage incubator (Sanyo, Osaka, Japan).
The miR-494 mimics, negative control mimics, miR-494 inhibitors, and negative control inhibitors were all purchased from Exiqon Inc. (Woburn, MA). The cDNA encoding the miR-494 precursor was cloned into the pMCS-CMV lentiviral vector purchased from GeneChem, Shanghai, P.R. China. The HIF-1α knockdown shRNA plasmid (HIF-1α KD) and Survivin knockdown shRNA plasmid (Survivin KD) were purchased from Santa Cruz Biotechnology (Santa Cruz, CA). The HIF-1α overexpression plasmid (HIF-1α OE) and Survivin overexpression plasmid (Survivin OE) were purchased from Addgene (Cambridge, MA). 293T packaging cells were cotransfected with pPackH1 packaging plasmid mix (SBI, Mountain View, CA) and lentiviral vectors using Fugene HD (Promega, Madison, WI). Viruses were harvested 48 h later and used to infect target cells.