Our previous studies demonstrated that MEG3 was significantly downregulated in neuroblastoma (NB) and its expression was negatively associated with the INSS stage. Overexpression of MEG3 promoted apoptosis and inhibited proliferation in NB cells. In this study, we discovered more potential functions and molecular mechanisms of MEG3 in NB. According to the database, MEG3 positively correlated with the NB survival rate and was negatively associated with malignant clinical features. Moreover, we determined that MEG3 was mainly located in the nucleus by nuclear-cytoplasmic separation and RNA fish assays. Upregulation of MEG3 in stably transfected cell lines was accomplished, and CCK8, colony formation, and EDU assays were performed, which indicated that MEG3 significantly suppressed cell proliferation. Both wound healing and transwell experiments demonstrated that MEG3 decreased cell migration and invasion. CHIRP enrichments showed the anticancer effects of MEG3 were probably linked to autophagy and the mTOR signaling pathway. LC3 fluorescence dots and western blots showed that MEG3 attenuated autophagy by inhibiting FOXO1, but not the mTOR signaling pathway. Furthermore, MEG3 inhibited metastasis through epithelial-mesenchymal transition via the mTOR signaling pathway. Consistent with the above results, downregulation of MEG3 facilitated NB malignant phenotypes. Mechanistically, MEG3 and EZH2 regulated each other via a negative feedback loop and promoted NB progression together. In conclusion, our findings suggested that MEG3 was a tumor suppressor in NB and could be a potential target for NB treatment in the future.

中文翻译：

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MEG3的下调通过FOXO1介导的自噬和mTOR介导的上皮-间质转化促进神经母细胞瘤的发展

我们之前的研究表明，MEG3 在神经母细胞瘤 (NB) 中显着下调，其表达与 INSS 阶段呈负相关。MEG3的过表达促进了NB细胞的凋亡并抑制了增殖。在这项研究中，我们发现了MEG3在NB中更多的潜在功能和分子机制。根据数据库，MEG3 与 NB 存活率呈正相关，与恶性临床特征呈负相关。此外，我们通过核质分离和 RNA 鱼测定确定 MEG3 主要位于细胞核中。在稳定转染的细胞系中完成了 MEG3 的上调，并进行了 CCK8、集落形成和 EDU 测定，这表明 MEG3 显着抑制了细胞增殖。伤口愈合和 transwell 实验均表明 MEG3 减少了细胞迁移和侵袭。CHIRP 富集显示 MEG3 的抗癌作用可能与自噬和 mTOR 信号通路有关。LC3 荧光点和蛋白质印迹显示 MEG3 通过抑制 FOXO1 而不是 mTOR 信号通路减弱自噬。此外，MEG3 通过 mTOR 信号通路通过上皮间质转化抑制转移。与上述结果一致，MEG3 的下调促进了 NB 恶性表型。在机制上，MEG3 和 EZH2 通过负反馈回路相互调节，共同促进 NB 进展。总之，我们的研究结果表明 MEG3 是 NB 中的肿瘤抑制因子，并且可能成为未来 NB 治疗的潜在靶点。