Fu Lin, Shi Jinlong, Liu Anqi, Zhou Lei, Jiang Mengmeng, Fu Huaping, Xu Keman, Li Dandan, Deng Ailing, Zhang Qingyi, Pang Yifan, Guo Yujie, Hu Kai, Zhou Jiansuo, Wang Yapeng, Huang Wenrong, Jing Yu, Dou Liping, Wang Lili, Xu Kailin, Ke Xiaoyan, Nervi Clara, Li Yonghui, Yu Li
Department of Hematology and Lymphoma Research Center, Peking University, Third Hospital, Beijing, 100191, China.
Department of Hematology, Chinese PLA General Hospital, Beijing, 100853, China.
Int J Cancer. 2017 Feb 1;140(3):653-661. doi: 10.1002/ijc.30481. Epub 2016 Nov 10.
MicroRNA-9-1(miR-9-1) plays an important role in the mechanism that regulates the lineage fate of differentiating hematopoietic cells. Recent studies have shown that miR-9-1 is downregulated in t (8; 21) AML. However, the pathogenic mechanisms underlying miR-9-1 downregulation and the RUNX1-RUNX1T1 fusion protein, generated from the translocation of t (8; 21) in AML, remain unclear. RUNX1-RUNX1T1 can induce leukemogenesis through resides in and functions as a stable RUNX1-RUNX1T1-containing transcription factor complex. In this study, we demonstrate that miR-9-1 expression increases significantly after the treatment of RUNX1-RUNX1T1 (+) AML cell lines with decitabine (a DNMT inhibitor) and trichostatin A (an HDAC inhibitor). In addition, we show that RUNX1-RUNX1T1 triggers the heterochromatic silencing of miR-9-1 by binding to RUNX1-binding sites in the promoter region of miR-9-1 and recruiting chromatin-remodeling enzymes, DNMTs, and HDACs, contributing to hypermethylation of miR-9-1 in t (8; 21) AML. Furthermore, because RUNX1, RUNX1T1, and RUNX1-RUNX1T1 are all regulated by miR-9-1, the silencing of miR-9-1 enhances the oncogenic activity of these genes. Besides, overexpression of miR-9-1 induces differentiation and inhibits proliferation in t (8; 21) AML cell lines. In conclusion, our results indicate a feedback circuitry involving miR-9-1 and RUNX1-RUNX1T1, contributing to leukemogenesis in RUNX1-RUNX1T1 (+) AML cell lines.
微小RNA-9-1（miR-9-1）在调节造血细胞分化谱系命运的机制中发挥重要作用。最近的研究表明，miR-9-1在t（8；21）急性髓系白血病（AML）中表达下调。然而，miR-9-1下调的致病机制以及AML中t（8；21）易位产生的RUNX1-RUNX1T1融合蛋白仍不清楚。RUNX1-RUNX1T1可通过存在于并作为稳定的含RUNX1-RUNX1T1转录因子复合物发挥作用来诱导白血病发生。在本研究中，我们证明用阿扎胞苷（一种DNA甲基转移酶抑制剂）和曲古抑菌素A（一种组蛋白去乙酰化酶抑制剂）处理RUNX1-RUNX1T1（+）AML细胞系后，miR-9-1表达显著增加。此外，我们表明RUNX1-RUNX1T1通过与miR-9-1启动子区域的RUNX1结合位点结合并募集染色质重塑酶、DNA甲基转移酶和组蛋白去乙酰化酶，触发miR-9-1的异染色质沉默，导致t（8；21）AML中miR-9-1的高甲基化。此外，由于RUNX1、RUNX1T1和RUNX1-RUNX1T1均受miR-9-1调控，miR-9-1的沉默增强了这些基因的致癌活性。此外，miR-9-1的过表达诱导t（8；21）AML细胞系分化并抑制其增殖。总之，我们的结果表明存在一个涉及miR-9-1和RUNX-RUNX1T1的反馈回路，促进RUNX1-RUNX1T1（+）AML细胞系中的白血病发生。
