Elhassan Gusai, Bu Xiangxue, Liu Jiaxin, Hou Shuai, Yan Jinsong, Lei Haixin
Institute of Cancer Stem Cell, Cancer Center, Dalian Medical University, Dalian, China.
Department of Molecular Biology, Faculty of Medical Laboratory Sciences, Al Neelain University, Khartoum, Sudan.
Noncoding RNA Res. 2025 May 28;14:117-128. doi: 10.1016/j.ncrna.2025.05.014. eCollection 2025 Oct.
Loss or decreased expression of lncRNA MEG3 is a frequent event in the progression of many different malignancies. Overexpression of MEG3 in breast cancer cell lines MCF7 or MDA-MB-231 prevented cell migration, whereas depletion of MEG3 in human mammary epithelial cell line MCF10A strikingly promoted cell migration. As RNA-protein interactions are vital for RNA to function, RNP assembled on MEG3 was purified using affinity purification followed by mass spectrometry, which revealed ∼600 proteins with the potential to interact with MEG3. Bioinformatic analysis on RNA-seq data from MCF7 with MEG3 overexpression and MCF10A with MEG3 depletion led to the identification of CXCR4 as the major downstream mediator negatively regulated by MEG3 that facilitated breast cancer cell migration. In addition, the chromatin regulator CTCF emerged as the MEG3-binding protein that might regulate CXCR4 expression after comparison of proteins presenting in MEG3 lncRNP to ChIP-seq data and GPSAdb data of CXCR4. Further evidence was provided to show CTCF upregulated the expression of CXCR4 at transcriptional level, whereas co-expression of MEG3 with CTCF abolished transcriptional activation of CXCR4. Overall, our study pinpoints the importance of MEG3/CTCF-CXCR4 axis in regulating migration of breast cancer cells and provides novel insight into the mechanism of lncRNA MEG3 in cancer development.
长链非编码RNA MEG3的缺失或表达降低在许多不同恶性肿瘤的进展过程中是常见事件。在乳腺癌细胞系MCF7或MDA-MB-231中过表达MEG3可阻止细胞迁移，而在人乳腺上皮细胞系MCF10A中敲低MEG3则显著促进细胞迁移。由于RNA-蛋白质相互作用对RNA发挥功能至关重要，因此利用亲和纯化结合质谱法对在MEG3上组装的核糖核蛋白（RNP）进行了纯化，结果显示约有600种蛋白质有可能与MEG3相互作用。对过表达MEG3的MCF7和敲低MEG3的MCF10A的RNA测序数据进行生物信息学分析，确定CXCR4是受MEG3负调控的主要下游介质，其促进乳腺癌细胞迁移。此外，通过将MEG3长链非编码核糖核蛋白中存在的蛋白质与CXCR4的染色质免疫沉淀测序（ChIP-seq）数据和GPSAdb数据进行比较，发现染色质调节因子CTCF是与MEG3结合的蛋白，可能调节CXCR4的表达。进一步的证据表明，CTCF在转录水平上上调CXCR4的表达，而MEG3与CTCF共表达则消除了CXCR4的转录激活。总体而言，我们的研究明确了MEG3/CTCF-CXCR4轴在调节乳腺癌细胞迁移中的重要性，并为长链非编码RNA MEG3在癌症发展中的作用机制提供了新的见解。
