[Expression of microRNA-223 in lymphocytic leukemia cells and its action mechanism]

This study was aimed to investigate the expression level and mechanism of microRNA-223 and LMO2 in acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL) cells and the mechanism. MicroRNA-223 mimics was transfected to increase the expression of MicroRNA-223 in the lymphocytes sorted by ficoll separation from the bone marrow mononuclear cells (BMMNC) of ALL and CLL patients. MicroRNA-223 inhibitor was transfected to decrease the expression of the MicroRNA-223 in the lymphocytes of normal controls. Then the expression of the MicroRNA-223 and LMO2 in transfected lymphocytes before and after cultivating for 72 hours were detected by RT-PCR, the apoptosis and cell cycle of these cells were measured by flow cytometery. The results indicated that before the transfection, the expression of MicroRNA-223 in ALL and CLL cells was (433.11 ± 144.88), which was significantly lower than that in the normal lymphocyte (949.59 ± 267.39); the expression of LMO2 was (807.10 ± 238.41), which was significantly higher than that in the normal lymphocytes (455.32 ± 176.83) (P < 0.05); after the transfection, the expression of MicroRNA-223 was (571.86 ± 142.00) in ALL and CLL cells, which was significantly higher than that before transfection (P < 0.05), but the expression of LMO2 was significantly lower than that before transfection (651.97 ± 230.12) (P < 0.05); in the normal control the expression of MicroRNA-223 obviously decreased (646.32 ± 172.93) (P < 0.05), the expression of LMO2 was significantly increased (541.27 ± 158.86.2) (P < 0.05). After transfection, the cell cycle G1/G2 phase and apoptosis changed in ALL and CLL cells. Before transfection the cell ratio in cell cycle G1/G2 phase was (94.75 ± 3.15)%, the cell ratio in S phase was (5.14 ± 3.12)%; after transfection the cell ratio in cell cycle G1/G2 phase was (97.03 ± 2.08)% and obviously increased (P < 0.05), the cell ratio in S phase was (2.97 ± 2.08)% and significantly decreased (P < 0.05). Before transfection the apoptosis rate was (54.47 ± 8.72)%, and obviously was higher than that after transfection (60.48 ± 8.81)%. And in the normal control, the cell ratio in G1/G2 phase was significantly higher than that after transfection [(96.73 ± 2.26)%, (94.55 ± 2.77)%, P < 0.05)], and the cell ratio in S phase was significantly increased [(3.25 ± 2.26)%, (5.45 ± 2.77)% (P < 0.05)]. The apoptotic rate in the ALL and CLL patients was significantly higher than that after the transfection [(54.47 ± 8.72)% vs (60.48 ± 8.81)%, respectively (P < 0.05)]. The apoptotic rate in the normal control was significantly lower than that after the transfection [(59.02 ± 10.20)%, (51.96 ± 10.20)%, respectively (P < 0.05)]. It is concluded that the expression of MicroRNA-223 decreases, and the expression of LMO2 increases in lymphocytic leukemia cells which leads to the lymphocytes over-proliferation and abnormal apoptosis, thus may be one of pathogenesis in lymphocytic leukemia.