miR-24-3p and miR-27a-3p promote cell proliferation in glioma cells via cooperative regulation of MXI1.

MicroRNAs (miRNAs) are small, non‑coding RNAs which regulate gene expression at the post-transcriptional level. Abnormal expression of miRNAs occurs frequently in tumors. Although the two miRNAs miR‑24‑3p and miR‑27a‑3p come from two duplicated gene clusters of miR‑23a~27a~24‑2 and miR‑23b~27b~24‑1 which are found to be deregulated in a variety of cancers, the role of cooperation of the two clusters and the function of the two miRNAs in tumors have not been completely characterized. Here, we show that overexpression of miR‑24‑3p and miR‑27a‑3p could promote cell proliferation using the MTT assay. By integrated bioinformatic analysis and experimental confirmation, we identified MXI1, which has been found to act as a tumor suppressor gene by affecting c‑Myc, as a direct target of miR‑24‑3p and miR‑27a‑3p. While targeting the MXI1 3' untranslated region by miR‑24‑3p or miR‑27a‑3p, luciferase activity was attenuated. The two miRNAs promote glioma cell proliferation via targeting MXI1 and the experiment was confirmed by the rescue experiments. Furthermore, our results show that two clusters of miR-23a~27a~24-2 and miR‑23b~27b~24‑1 regulate MXI1 synergistically. These findings reveal, for the first time, the novel functions of cooperation of miR‑24‑3p and miR‑27a‑3p from two clusters in promoting cell proliferation through MXI1. Additionally, we observed that miR‑27a‑3p is upregulated in glioma tissues.