CircNFIX knockdown inhibited AML tumorigenicity by the miR-876-3p/TRIM31 axis

Acute myeloid leukemia (AML) is one of the most common malignant myeloid diseases in adults with a dismal prognosis. We aimed to explore the effects of circNFIX on the proliferation and apoptosis of AML cells. The expressions of circNFIX, miR-876-3p and tripartite motif (TRIM) 31 in the bone marrow specimens of AML patients and AML cell lines were detected by qRT-PCR or western blot. Cell proliferation was evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 5-ethynyl-29-deoxyuridine (EdU) assays. Cell cycle and apoptosis were analyzed by flow cytometry. Western blot was used to detect protein expression. The relationship between miR-876-3p and circNFIX or TRIM31 was identified by dual-luciferase reporter assay or RNA pull-down assay. The expression level of circNFIX was significantly increased in the bone marrow samples of AML patients and AML cells when compared with normal controls. CircNFIX silencing inhibited AML cell proliferation and promoted apoptosis. Inhibition of miR-876-3p reversed the effect of circNFIX knockdown on AML cell progression. In addition, circNFIX indirectly regulated TRIM31 through miR-876-3p. Further, TRIM31 overexpression counteracted the effect of circNFIX silencing on AML cell proliferation and apoptosis. CircNFIX knockdown could suppress the proliferation and induce the apoptosis of AML cells by targeting the miR-876-3p/TRIM31 axis.

急性髓系白血病（Acute myeloid leukemia，AML）是成人最常见的恶性髓系疾病之一，预后极差。本研究旨在探讨circNFIX对AML细胞增殖与凋亡的影响。研究采用实时定量聚合酶链反应（quantitative real-time polymerase chain reaction，qRT-PCR）或蛋白质印迹（Western blot）技术，检测AML患者骨髓标本及AML细胞系中circNFIX、miR-876-3p及三结构域蛋白31（tripartite motif 31，TRIM31）的表达水平；通过噻唑蓝比色法（3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐，MTT）与5-乙炔基-2'-脱氧尿苷（5-ethynyl-2'-deoxyuridine，EdU）实验评估细胞增殖能力；借助流式细胞术分析细胞周期与凋亡水平；采用蛋白质印迹法检测蛋白表达情况。此外，通过双荧光素酶报告基因实验及RNA pull-down实验，验证miR-876-3p与circNFIX或TRIM31之间的调控关系。实验结果表明：与正常对照组相比，AML患者骨髓标本及AML细胞中circNFIX的表达水平显著升高；沉默circNFIX可抑制AML细胞增殖并促进其凋亡；抑制miR-876-3p可逆转沉默circNFIX对AML细胞进程的影响；circNFIX可通过miR-876-3p间接调控TRIM31的表达；过表达TRIM31可抵消沉默circNFIX对AML细胞增殖与凋亡的作用。综上，沉默circNFIX可通过靶向调控miR-876-3p/TRIM31轴，抑制AML细胞增殖并诱导其凋亡。