miRNA Sponge介导的miR-17和miR-20a基因沉默的抗白血病作用机制

Anti-leukemia Mechanism of miR-17 and miR-20a Silencing Mediated by miRNA Sponge

本研究旨在检测急性白血病患者中miR-17和miR-20a前体的表达水平,并探讨miRNA Sponge介导的miR-17和miR-20a沉默的抗白血病作用机制。采用荧光实时定量PCR方法检测初治急性白血病患者及8种白血病细胞株中miR-17和miR-20a前体的表达水平,分析其在各型白血病中的表达情况。利用前期构建的针对miR-17和miR-20a基因的miRNA Sponge慢病毒表达载体,感染高表达miR-17和miR-20a的Jurkat细胞株;用CCK-8方法及流式细胞术分别检测miR-17和miR-20a沉默对Jurkat细胞增殖能力及细胞周期的影响。结果表明:初治急性白血病患者中miR-17和miR-20a前体的表达明显高于正常对照(P<0.05);且与急性髓系白血病患者相比,急性淋巴细胞白血病患者中的表达量更高;然而二者表达量与患者外周血高白细胞计数无明显相关性(P>0.05)。miR-17和miR-20a沉默能抑制Jurkat细胞的增殖,使细胞周期阻滞于G1—S期,同时促进细胞的凋亡。结论:急性白血病患者中miR-17和miR-20a呈过表达,可能参与白血病的发生、发展;高表达的miR-17和miR-20a可通过在转录后抑制P21和E2F1表达,从而促进细胞增殖及细胞周期G1—S期转换,抑制细胞凋亡。

This study was aimed to quantitatively detect the expression levels of pre-miR-17 and pre-miR-20a in acute leukemia patients and eight kinds of leukemia cell lines, and to investigate the anti-leukemia mechanism of miR-17 and rniR-20a silence mediated by miRNA Sponge. Quantitative real-time PCR was used to detect the mRNA expression levels of pre-miR-17 and pre-miR-20a in patients with various types of leukemia and leukemia cell lines. The Jurkat cells over-expressing miR-17 and miR-20a were transfected with recombinant lentivirus-transfecting units targeted at miR-17 and miR-20a plus 6 μg/ml of polybrene. Then the proliferation ability and cell cycle of Jurkat cells was evaluated by CCK-8 and flow cytometry respectively. The results showed that the expression level of pre-miR-17 and pre-miR-20a in all leukemia patients was significantly higher than that in normal group （ P 〈 0.05 ）, the expression of pre-miR-17 and pre-miR-20a in acute lymphoid leukemia was significantly higher than that in acute myeloid leukemia（ P 〈 0.05 ）, and the pre-miR-17 and pre-miR-20a expression level did not correlate significantly with high white blood cell count 〉 20.0 × 109/L（P 〉0.05）. The miR-17 and miR-20a silencing mediated by miRNA Sponge led to a significant decrease of cell growth, restored G1 accumulation and increase of cell apoptosis. It is concluded that the expression of miR-17 and miR- 20a is upregulated in leukemia patients, which may contribute to leukemogenesis. Over-expressed miR-17 and miR-20a promote cell growth and cell cycle progression, and inhibit apoptosis through negatively-regulating P21 and E2F1 after- transcriptionally.