Tan Yee Sun, Kim MinJung, Kingsbury Tami J, Civin Curt I, Cheng Wen-Chih
Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America; Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America; Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
PLoS One. 2014 Nov 4;9(11):e111777. doi: 10.1371/journal.pone.0111777. eCollection 2014.
MicroRNAs (miRs) regulate essentially all cellular processes, but few miRs are known to inhibit growth of precursor-B acute lymphoblastic leukemias (B-ALLs). We identified miR-509 via a human genome-wide gain-of-function screen for miRs that inhibit growth of the NALM6 human B-ALL cell line. MiR-509-mediated inhibition of NALM6 growth was confirmed by 3 independent assays. Enforced miR-509 expression inhibited 2 of 2 additional B-ALL cell lines tested, but not 3 non-B-ALL leukemia cell lines. MiR-509-transduced NALM6 cells had reduced numbers of actively proliferating cells and increased numbers of cells undergoing apoptosis. Using miR target prediction algorithms and a filtering strategy, RAB5C was predicted as a potentially relevant target of miR-509. Enforced miR-509 expression in NALM6 cells reduced RAB5C mRNA and protein levels, and RAB5C was demonstrated to be a direct target of miR-509. Knockdown of RAB5C in NALM6 cells recapitulated the growth inhibitory effects of miR-509. Co-expression of the RAB5C open reading frame without its 3' untranslated region (3'UTR) blocked the growth-inhibitory effect mediated by miR-509. These findings establish RAB5C as a target of miR-509 and an important regulator of B-ALL cell growth with potential as a therapeutic target.
微小RNA（miR）基本上调控着所有细胞过程，但已知能抑制前体B淋巴细胞急性淋巴细胞白血病（B-ALL）生长的miR却很少。我们通过对抑制NALM6人B-ALL细胞系生长的miR进行全基因组功能获得性筛选，鉴定出了miR-509。通过3项独立实验证实了miR-509介导的对NALM6生长的抑制作用。在另外2种测试的B-ALL细胞系中，强制表达miR-509可抑制其生长，但对3种非B-ALL白血病细胞系则无此作用。转导了miR-509的NALM6细胞中，活跃增殖细胞数量减少，凋亡细胞数量增加。使用miR靶标预测算法和筛选策略，预测RAB5C是miR-509的一个潜在相关靶标。在NALM6细胞中强制表达miR-509可降低RAB5C的mRNA和蛋白水平，并且证实RAB5C是miR-509的直接靶标。在NALM6细胞中敲低RAB5C可重现miR-509的生长抑制作用。共表达不含3'非翻译区（3'UTR）的RAB5C开放阅读框可阻断miR-509介导的生长抑制作用。这些发现确定RAB5C是miR-509的靶标以及B-ALL细胞生长的重要调节因子，具有作为治疗靶标的潜力。
