Medical Supplies Center of PLA General Hospital, Beijing 100853, China.
Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Department of Pharmacology, School of Pharmacy, Air Force Medical University, Xi'an 710032, China.
Acta Biochim Biophys Sin (Shanghai). 2023 May 30;55(5):809-817. doi: 10.3724/abbs.2023074.
ING5 belongs to the inhibitor of growth (ING) candidate tumor suppressor family, which is involved in multiple cellular functions, such as cell cycle regulation, apoptosis, and chromatin remodelling. Previously, we reported that ING5 overexpression inhibits EMT by regulating EMT-related molecules, including Snail1, at the mRNA and protein levels. However, the mechanisms remain unclear. In the current study, we identify that ING5 overexpression induces the upregulation of miR-34c-5p. The expression levels of both ING5 and miR-34c-5p in NSCLC tissues from the TCGA database are decreased compared with that in adjacent tissues. Higher expression levels of both ING5 and miR-34c-5p predict longer overall survival (OS). Snail1 is the target gene of miR-34c-5p, as predicted by an online database, which is further verified by a dual-luciferase reporter assay. The expression level of Snail1 in NSCLC cells is markedly reduced following miR-34c-5p overexpression, leading to the inactivation of the Snail1 downstream TGF-β/Smad3 signaling pathway. The TGF-β signaling-specific inhibitor LY2157299 reverses the enhanced EMT, proliferation, migration, and invasion abilities induced by the miR-34c-5p inhibitor. Furthermore, tail vein injection of miR-34c-5p agomir inhibits xenografted tumor metastasis. Overall, this study concludes that miR-34c-5p, induced by ING5 overexpression, is a tumor suppressor that targets Snail1 and mediates the inhibitory effects of ING5 on the EMT and invasion of NSCLC cells. These results provide a novel mechanism mediating the antitumor effects of ING5.
ING5 属于生长抑制剂（ING）候选肿瘤抑制因子家族，参与多种细胞功能，如细胞周期调节、细胞凋亡和染色质重塑。之前，我们报道过 ING5 过表达通过调节 EMT 相关分子，包括 Snail1，在 mRNA 和蛋白水平上抑制 EMT。然而，其机制尚不清楚。在本研究中，我们发现 ING5 过表达诱导 miR-34c-5p 的上调。TCGA 数据库中 NSCLC 组织中 ING5 和 miR-34c-5p 的表达水平均低于相邻组织。ING5 和 miR-34c-5p 的表达水平均较高预示着总生存期（OS）更长。Snail1 是 miR-34c-5p 的靶基因，这是通过在线数据库预测的，进一步通过双荧光素酶报告基因实验得到验证。miR-34c-5p 过表达后，NSCLC 细胞中 Snail1 的表达水平显著降低，导致 Snail1 下游 TGF-β/Smad3 信号通路失活。TGF-β 信号特异性抑制剂 LY2157299 逆转了由 miR-34c-5p 抑制剂诱导的 EMT、增殖、迁移和侵袭能力的增强。此外，尾静脉注射 miR-34c-5p agomir 抑制异种移植肿瘤转移。总之，本研究表明，ING5 过表达诱导的 miR-34c-5p 是一种肿瘤抑制因子，靶向 Snail1 并介导 ING5 对 NSCLC 细胞 EMT 和侵袭的抑制作用。这些结果提供了一种介导 ING5 抗肿瘤作用的新机制。
