Objective  To explore the changes in the transcription levels of microRNAs(miRNAs) in endometrial glandular epithelial cells (EECs) under hypoxia and their effects on apoptosis.

  Methods  EECs were seeded into six-well plates in logarithmic growth phase(1×10⁵ cells/well), and divided into two groups: hypoxia group and control group. The cells in both hypoxia group and the control group were placed in a hypoxic environment (the volume ratio of O₂∶N₂∶CO₂ was 1∶94∶5) and cultured in normoxic environment (O₂∶CO₂ volume ratio of 95∶5). All cells were collected after they were cultured 4 h, and Trizol was added into the cells and total RNAs were extracted. High-throughput sequencing was used to detect the changes of miRNAs expression profiles in the two groups of EECs. Subsequently, realtime fluorescence quantitative polymerase chain reaction (RT-PCR) was used to detect the gene expression of miR-7704 and miR-7974. Flow cytometry was used to detect the apoptosis of EECs. The protein expression changes of p53 and apoptosis-related proteins were detected by Western blot.

  Results  High-throughput sequencing detected the expression levels of 21 common miRNAs. Compared with the control group, 16 miRNAs were up-regulated and 5 miRNAs were down-regulated in the EECs of the hypoxia group; the expression of miR-7704 and miR-7974 decreased most significantly in the hypoxia group(all P < 0.05). RT-PCR results showed that compared with the control group, the relative expression levels of miR-7704 and miR-7974 in EECs of the hypoxia group decreased by 20% and 80%, respectively. The results of flow cytometry showed that the ratio of early apoptotic cells and late apoptotic cells in the hypoxia group was higher than that in the control group (all P < 0.001). The results of Western blot showed that the expression of p53 in EECs in the hypoxia group increased, and the expression of the anti-apoptotic protein B-cell lymphoma-2 decreased compared with the control group(all P < 0.05).

  Conclusions  Hypoxic environment can induce changes in the expression profile of miRNAs in EECs, among which the down-regulation of miR-7974 is the most significant. p53 may be the target protein of miR-7974, and hypoxia-induced EEC apoptosis may be achieved by down-regulating the level of miR-7974 and promoting the expression of p53.