miR-181a down-regulates MAP2K1 to enhance adriamycin sensitivity in leukemia HL-60 cells

J.-J. Wang, J.-P. Yu

Department of Laboratory, Nuclear Industry 215 Hospital of Shaanxi Province, Xianyang, Shanxi, China. yuyujianping@126.com

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• Hematology

OBJECTIVE: MAPK kinase 1 (MEK1), also known as MAP2K1, plays a role in activating extra-cellular signal-regulated protein kinase/mitogen-activated protein kinase (ERK/MAPK) signaling pathway to regulate cell proliferation and apoptosis. The abnormal expression of MAP2K1 is associated with leukemia. Bioinformatics analysis showed the targeted relationship between microRNA-181a (miR-181a) and the 3’-UTR of MAP2K1. This study aimed to investigate the role of miR-181a in regulating MAP2K1 expression, the effects on leukemic cell proliferation, apoptosis, and adriamycin (ADM) resistance.

MATERIALS AND METHODS: Dual luciferase reporter gene assay was applied to confirm the targeted relationship between miR-181a and MAP2K1. ADM resistant cell line HL-60/ADM was established. MiR-181a and MAP2K1 expressions were detected. HL-60/ADM cells were cultured in vitro and divided into two groups, including microRNA-Normal control (miR-NC) group and miR-181a mimic group. MAP2K1, phosphorylated MAP2K1 (p-MAP2K1), and phosphorylated ERK (p-ERK) protein expressions were tested. Cell apoptosis was assessed with flow cytometry. Cell proliferation was determined using EdU staining.

RESULTS: There is a targeted regulatory relationship between miR-181a and MAP2K1 mRNA. miR-181a expression was significantly lower, while MAP2K1 mRNA and protein expressions were markedly higher in HL-60/ADM cells than HL-60 cells (p<0.05). Transfection of miR-181a mimic markedly reduced expressions of MAP2K1, p-MAP2K1, and p-ERK in HL-60/ADM cells, enhanced cell apoptosis, and weakened cell proliferation compared to miR-NC (p<0.05).

CONCLUSIONS: MiR-181a reduction and MAP2K1 elevation were related to ADM resistance in leukemia cells. Up-regulation of miR-181a expression inhibited leukemia cell proliferation, induced apoptosis, and reduced ADM resistance via targeting MAP2K1 expression and ERK/MAPK signaling pathway.

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