Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education and Tianjin, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.
Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan, China.
Acta Biochim Biophys Sin (Shanghai). 2017 Dec 1;49(12):1112-1121. doi: 10.1093/abbs/gmx114.
Although many miRNAs are reported to be involved in tumor formation and progression, the effect of miR-219a-5p on breast cancer metastasis is not well-known. The aim of this study is to investigate the effect of miR-219a-5p on the migratory ability and epithelial-mesenchymal transition (EMT) of breast cancer cells. First, miR-219a-5p was found to be highly expressed in low-invasive breast cancer MCF-7 cells, but lowly expressed in high-invasive breast cancer MDA-MB-231 cells. Wound scratch assay and transwell assay showed that miR-219a-5p inhibited the migratory ability of MDA-MB-231 cells. miR-219a-5p also suppressed the cellular EMT, confirmed by suppressing the expression of mesenchymal markers vimentin and N-cadherin and increasing the expression of epithelial marker E-cadherin. Using the epithelial-mesenchymal-epithelial model in MCF-7 cells, we confirmed that the level of miR-219a-5p was highly expressed in epithelial-type cells and lowly expressed in mesenchymal-type cells. Importantly, we identified myocardin-related transcription factor A (MRTF-A) as a novel potential target gene of miR-219a-5p. Overexpression of miR-219a-5p in MDA-MB-231 cells could inhibit the expression of MRTF-A as revealed by real-time PCR and western blot analysis. miR-219a-5p inhibited the transcription of MRTF-A by targeting the 3'UTR of MRTF-A, which was confirmed by wild-type or mutant MRTF-A 3'UTR luciferase reporter system. Furthermore, knockdown of MRTF-A using siRNA for MRTF-A could depress breast cell migration. In conclusion, our present study revealed the tumor suppressive role of miR-219a-5p in regulating breast cancer migration by targeting MRTF-A, suggesting that miR-219a-5p might be a therapeutic target in breast cancer through regulating EMT.
虽然有许多 miRNA 被报道参与肿瘤的形成和进展，但 miR-219a-5p 对乳腺癌转移的影响尚不清楚。本研究旨在探讨 miR-219a-5p 对乳腺癌细胞迁移能力和上皮-间充质转化（EMT）的影响。首先，发现 miR-219a-5p 在低侵袭性乳腺癌 MCF-7 细胞中高表达，而在高侵袭性乳腺癌 MDA-MB-231 细胞中低表达。划痕实验和 Transwell 实验表明，miR-219a-5p 抑制 MDA-MB-231 细胞的迁移能力。miR-219a-5p 还抑制了细胞 EMT，通过抑制间充质标志物波形蛋白和 N-钙黏蛋白的表达和增加上皮标志物 E-钙黏蛋白的表达来证实。通过 MCF-7 细胞中的上皮-间充质-上皮模型，我们证实 miR-219a-5p 的水平在上皮型细胞中高表达，在间充质型细胞中低表达。重要的是，我们确定肌球蛋白相关转录因子 A（MRTF-A）是 miR-219a-5p 的一个新的潜在靶基因。实时 PCR 和 Western blot 分析显示，MDA-MB-231 细胞中 miR-219a-5p 的过表达可抑制 MRTF-A 的表达。miR-219a-5p 通过靶向 MRTF-A 的 3'UTR 抑制 MRTF-A 的转录，这通过野生型或突变型 MRTF-A 3'UTR 荧光素酶报告系统得到证实。此外，使用 MRTF-A 的 siRNA 敲低 MRTF-A 可抑制乳腺细胞迁移。总之，本研究揭示了 miR-219a-5p 通过靶向 MRTF-A 抑制乳腺癌迁移的肿瘤抑制作用，表明 miR-219a-5p 可能通过调节 EMT 成为乳腺癌的治疗靶点。
