Effects of MiR-221-Mediated Wnt/β- Catenin Signaling Pathway on Biological Activity of Childhood Acute Lymphoblastic Leukemia Cells

Abstract

To study the effects of miR-221 on the biological activity of childhood acute lymphoblastic leukemia cells and its mechanism. Bone marrow mononuclear cells (BMNC) were isolated from bone marrow samples of ALL children diagnosed in our hospital from May 2018 to November 2018. The cells were divided into control group, miR-221-NC group and miR-221 group. After transfection according to the instructions of Lipofectamine 2000 kit, the levels of miR-221 in each group were detected by RT-PCR. Flow cytometry was used to detect the effects of miR-221 on cell cycle and apoptosis. Transwell assay was used to detect cell migration and invasion. Western blot was used to detect the effects of miR-221 on proliferating cell nuclear antigen (PCNA), Caspase 3, Cyclin D1 and MMP-9 proteins in BMNC. Luciferase reporter gene assay was used to detect the targeting relationship between miR-221 and Wnt gene. The expression level of miR-221 in the miR-221 group was significantly higher than that in the control group and the miR-221-NC group (P＜0.05). MTT assay showed that, after transfection for 2, 3, 4 and 5 days, the cell proliferation level in miR-221 group was significantly lower than that in the control group and the miR-221-NC group (P＜0.05). The cell ratio of G0/G1 phase was (73.25±8.1)% in the miR-221 group, which was significantly higher than that in the control group and the miR-221-NC group (P＜0.05); moreover, the cell ratio of S phase in the miR-221 group was (12.37±1.6)%，which was significantly lower than that in the control group and the miR-221-NC group (P＜0.05). The percentage of apoptotic cells in the miR-221 group was (24.68±3.87)%, which was significantly higher than that in the control group and the miR-221-NC group (P＜0.05). Transwell cell invasion experiment showed that the number of invasive cells in the miR-221 group was 23.42±3.62, which was significantly lower than that in the control group and the miR-221-NC group (P＜0.05). Transwell cell migration assay showed that the number of migrating cells in the miR-221 group was 34.86±5.32, which was significantly lower than that in the control group and the miR-221-NC group (P＜0.05). The relative level of PCNA, Cyclin D1 and MMP-9 in the miR-221 group was 0.26±0.03, 0.17±3.61 and 0.14±0.02, respectively, which was significantly lower than those in the control group and the miR-221-NC group (P＜0.05), while the relative level of Caspase-3 in the miR-221 group was 0.37±0.05, which was significantly higher than that in the control group and the miR-221-NC group (P＜0.05). Luciferase reporter assay showed that the activity of luciferase in Wnt wild type plasmid was significantly inhibited by miR-221 (P＜0.05). miR-221 can inhibit the proliferation, migration and invasion of BMNC, moreover can promote cell apoptosis, which may be related with the inhibition of Wnt/β- catenin signaling pathway.