BACKGROUND Previous studies have shown that the copy number of microRNA (miR)-124 is decreased in diffuse large B cell lymphoma (DLBCL), and that miR-124 is a tumor suppressor by targeting NF-κB p65 in B-cell lymphoma. In turn, miR-124 expression is regulated by transcription factors such as HNF4α, ETS2, and p53. However, whether and how miR-124 transcription is modulated by NF-κB transcription factors remain unknown in DLBCL. OBJECTIVE To investigate whether the activation of NF-κB signaling could inhibit the expression of miR-124, possibly contributing to the pathogenesis of DLBCL. METHODS Potential transcription factors regulating miR-124 transcription were predicted using the Transfac software. The cellular effects of NF-κB p65 on miR-124 were examined by MTS assay, Western blot assay, qPCR, and chromatin immunoprecipitation (ChIP) assays using DLBCL cell lines. RESULTS Inhibition of NF-κB signals using Bay11-7085 increased miR-124 expression whereas exposure to TNF-α decreased it. Ectopic expression of p65 suppressed miR-124 expression, suggesting that p65 may be a transcriptional repressor of miRNA-124. Pharmacological analyses showed that phosphorylated/activated p65 downregulates miR-124 via two signaling pathways: (1) TAK1/IKKα-IKKβ/IκBα and (2) MAPK/p65. Moreover, ChIP assay demonstrated that p65 directly regulates miR-124 by binding to the NF-κB consensus sequence in its promoter region. Finally, we also confirmed that stable ectopic expression of miR-124 suppresses cell proliferation and survival. CONCLUSION Taken together, our study uncovered a mechanism by which active NF-κB signaling disrupts the function of miR-124 as a tumor suppressor in DLBCL.

中文翻译：

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NF-κBp65抑制弥漫性大B细胞淋巴瘤中的microRNA-124转录。

背景技术以前的研究表明，弥漫性大B细胞淋巴瘤（DLBCL）中的microRNA（miR）-124的拷贝数减少，并且miR-124通过靶向B细胞淋巴瘤中的NF-κBp65来抑制肿瘤。反过来，miR-124表达受转录因子（例如HNF4α，ETS2和p53）调控。但是，在DLBCL中，miR-124转录是否以及如何被NF-κB转录因子调节仍然未知。目的探讨NF-κB信号通路的激活是否能抑制miR-124的表达，可能与DLBCL的发病有关。方法使用Transfac软件预测可能调控miR-124转录的转录因子。通过MTS分析，蛋白质印迹分析，qPCR和NF-κBp65对miR-124的细胞作用 和使用DLBCL细胞系的染色质免疫沉淀（ChIP）分析。结果使用Bay11-7085抑制NF-κB信号可增加miR-124表达，而暴露于TNF-α则可降低其表达。p65的异位表达抑制了miR-124的表达，表明p65可能是miRNA-124的转录阻遏物。药理分析表明，磷酸化/激活的p65通过两个信号通路下调miR-124：（1）TAK1 /IKKα-IKKβ/IκBα和（2）MAPK / p65。此外，ChIP分析表明，p65通过与其启动子区域的NF-κB共有序列结合而直接调节miR-124。最后，我们还证实了miR-124的稳定异位表达可抑制细胞增殖和存活。结论总而言之，