Upregulated miR-1258 regulates cell cycle and inhibits cell proliferation by directly targeting E2F8 in CRC.

OBJECTIVES: MicroRNAs (miRNAs) as small noncoding RNA molecules function by regulating their target genes negatively. MiR-1258 was widely researched in multicancers, but its role remains unclear in colorectal cancer (CRC).
METHODS: The expression of miR-1258 and its specific target gene were detected in human CRC specimens and cell lines by miRNA RT-PCR, qRT-PCR and Western blot. The effects of miR-1258 on CRC proliferation were evaluated using CCK-8 assays, EdU incorporation, colony formation assays and cell-cycle assays; in vitro and the in vivo effects were investigated using a mouse tumorigenicity model. Luciferase reporter and RIP assays were employed to identify interactions between miR-1258 and its specific target gene.
RESULTS: MiR-1258 was downregulated in CRC tissues and CRC cell lines, and upregulated miR-1258 was proved to inhibit proliferation and arrest cell cycle at G0/G1 in vitro and vivo. Luciferase reporter, RIP and western blot assays revealed E2F8 to be a direct target of miR-1258. The effects of miR-1258 in proliferation and cell cycle regulation can be abolished by E2F8 through rescue experiments. By directly targeting E2F8, miR-1258 influenced the expression of several cell-cycle factors, including cyclin D1 (CCND1) and cyclin dependent kinase inhibitor 1A (p21).
CONCLUSION: MiR-1258 may function as a suppressive factor by negatively controlling E2F8, thus, highlighting the potential role of miR-1258 as a therapeutic target for human CRC.