MicroRNA-769-3p down-regulated NDRG1 and enhanced apoptosis in MCF-7 during reoxygenation.

In this study, breast cancer MCF-7 cells were cultured under 0.5% oxygen for 24 h followed by 24 h of reoxygenation. Cells was harvested at 0, 1, 12, and 24 h during reoxygenation, and examined the miRNA profile by Nanostring nCounter. Forty-three miRNAs had dramatic changes as compared with 0 h upon reoxygenation, with 63% (n=27) of the miRNAs up-regulated upon reoxygenation. Among these miRNAs, miR-769-3p, which was down-regulated in MCF-7 upon reoxygenation, was chosen for further investigation. The hypothesis was that the down-regulation of NDRG1 upon reoxygenation was regulated by miRNAs. To examine wether miRNAs regulate NDRG1 under 0.5% O2 concentrations, the miRNA expression profiles of MCF-7 cells under reoxygenation were examined. Cells were harvested at 0 (hypoxia control), 1, 12, and 24 h upon reoxygenation. Each profile was done in triplicate. The genomic profile of miRNAs was measured using NanoString nCounter® miRNA Expression Assays.