Department of Respiratory Medicine, Affiliated Wujiang Hospital of Nantong University, Suzhou, China; Department of Respiratory Medicine, the First Affiliated Hospital of Soochow University, Suzhou, China.
Department of Radiotherapy and Oncology, Affiliated Kunshan Hospital of Jiangsu University, Suzhou, China.
Cancer Lett. 2020 Apr 28;476:129-139. doi: 10.1016/j.canlet.2020.02.018. Epub 2020 Feb 17.
Bromodomain-containing protein 4 (BRD4) overexpression in non-small cell lung cancer (NSCLC) promotes cancer progression. Here, we show that miR-4651 selectively targets and negatively regulates BRD4 in A549 and primary human NSCLC cells. RNA pull-down experiments confirmed that miR-4651 directly binds to BRD4 mRNA. Further, ectopic overexpression of miR-4651 in A549 cells and primary NSCLC cells decreased BRD4 3'-UTR luciferase reporter activity and its expression, whereas miR-4651 inhibition elevated both. Functional studies demonstrated that NSCLC cell growth, proliferation, and migration were suppressed with ectopic miR-4651 overexpression but enhanced with miR-4651 inhibition. BRD4 re-expression using a 3'-UTR mutant BRD4 reversed A549 cell inhibition induced by miR-4651 overexpression. Further, miR-4651 overexpression or inhibition failed to alter the functions of BRD4-KO A549 cells. In vivo, miR-4651-overexpressing A549 xenografts grew slowly than control A549 xenografts in severe combined immunodeficient mice. Finally, miR-4651 was downregulated in human NSCLC tissues, correlating with BRD4 elevation. Together, miR-4651 targets BRD4 to inhibit NSCLC cell growth in vitro and in vivo.
溴结构域蛋白 4（BRD4）在非小细胞肺癌（NSCLC）中的过表达促进了癌症的进展。在这里，我们表明 miR-4651 选择性地靶向和负调控 A549 和原发性人非小细胞肺癌细胞中的 BRD4。RNA 下拉实验证实 miR-4651 可直接结合 BRD4 mRNA。此外，miR-4651 在 A549 细胞和原发性 NSCLC 细胞中的过表达降低了 BRD4 3'-UTR 荧光素酶报告基因活性及其表达，而 miR-4651 抑制则升高了两者。功能研究表明，过表达 miR-4651 可抑制 NSCLC 细胞的生长、增殖和迁移，但抑制 miR-4651 则增强了这些作用。使用 3'-UTR 突变型 BRD4 进行 BRD4 再表达可逆转 miR-4651 过表达诱导的 A549 细胞抑制。此外，miR-4651 过表达或抑制均未能改变 BRD4-KO A549 细胞的功能。体内，miR-4651 过表达的 A549 异种移植在严重联合免疫缺陷小鼠中比对照 A549 异种移植生长缓慢。最后，miR-4651 在人非小细胞肺癌组织中下调，与 BRD4 升高相关。总之，miR-4651 通过靶向 BRD4 抑制 NSCLC 细胞在体外和体内的生长。
