Colorectal cancer (CRC) is one of the leading causes of death worldwide, and hence, there is a need to elucidate the molecular mechanisms contributing to the progression of CRC. In this study, we aimed at assessing the role of long non-coding RNA NBPF4 on the tumorigenesis of CRC. Silencing or overexpression experiments were performed on HCT116 and SW260 in vitro models. BALB/c athymic female nude mice aged 5–6 weeks were used as in vivo models. To assess the relationship between NBPF4 and its regulatory RNA pull-down assay, RNA immunoprecipitation, luciferase activity, Western blotting and qRT-PCR were employed. Initially, we identified that NBPF4 was downregulated in CRC tissues and cell lines. Furthermore, we observed that NBPF4 decreased tumorigenesis in both in vitro and in vivo models. Additionally, we identified that ETFA was highly expressed in CRCs and was negatively associated with NBPF4. Subsequently, we identified that EZH2, a transcriptional factor, activated ETFA by enhancing the methylation of its promoter, and EZH2 was also highly regulated in CRCs. Using COAD and READ databases, we confirmed that EZH2 and ETFA were positively correlated. Furthermore, we identified NBPF4 and EZH2 were targets for ZFP36, which bound and positively regulated NBPF4. This prevented NBPF4 from binding to its negative regulator miR-17-3p. Our results demonstrated that NBPF4 downregulated EZH2 and stabilized itself by binding to ZFP36, thus escaping from inhibition by miR-17-3p, which allowed mitigation of CRC through inhibition of ETFA.

中文翻译：

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NBPF4 通过调节 EZH2 相关 ETFA 来减轻结直肠癌的进展

结直肠癌 (CRC) 是世界范围内导致死亡的主要原因之一，因此，有必要阐明促成 CRC 进展的分子机制。在本研究中，我们旨在评估长链非编码 RNA NBPF4 在 CRC 肿瘤发生中的作用。对 HCT116 和 SW260 体外模型进行沉默或过表达实验。使用 5-6 周龄的 BALB/c 无胸腺雌性裸鼠作为体内模型。为了评估 NBPF4 与其调节性 RNA 下拉测定之间的关系，采用 RNA 免疫沉淀、荧光素酶活性、蛋白质印迹和 qRT-PCR。最初，我们发现 NBPF4 在 CRC 组织和细胞系中被下调。此外，我们观察到 NBPF4在体外和体内均降低了肿瘤发生楷模。此外，我们发现 ETFA 在 CRC 中高度表达，并且与 NBPF4 呈负相关。随后，我们发现转录因子 EZH2 通过增强其启动子的甲基化来激活 ETFA，并且 EZH2 在 CRC 中也受到高度调节。使用 COAD 和 READ 数据库，我们确认 EZH2 和 ETFA 呈正相关。此外，我们确定 NBPF4 和 EZH2 是 ZFP36 的目标，它结合并正向调节 NBPF4。这阻止了 NBPF4 与其负调节因子 miR-17-3p 结合。我们的结果表明，NBPF4 下调 EZH2 并通过与 ZFP36 结合来稳定自身，从而摆脱 miR-17-3p 的抑制，从而通过抑制 ETFA 来缓解 CRC。