Qi Liqiang, Sun Bo, Yang Beibei, Lu Su
Department of Breast Surgical Oncology, Cancer Institute and Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 17 Panjiayuan Nanli, Chaoyang District, Beijing, 100021, China.
The 2nd Department of Breast Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.
Cancer Cell Int. 2021 Feb 25;21(1):133. doi: 10.1186/s12935-021-01816-z.
Circular RNAs (circRNAs) have been demonstrated to play significant roles in regulating gene expression in tumorigenesis, including breast cancer (BC). This study was designed to explore the role and underlying molecular mechanisms of circMMP11 in BC.
The real-time quantitative polymerase chain reaction (RT-qPCR) assay was used for examining expression of circMMP11, microRNA-625-5p (miR-625-5p), and Zinc finger E-box binding homeobox-2 (ZEB2). The protein expression of ZEB2, Vimentin, and E-cadherin was assessed by western blot assay. The proliferation ability of BC cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazol-3-ium bromide (MTT) and colony-forming assays. The transwell assay was used to measure migration and invasion of BC cells. The apoptotic cells were examined by flow cytometry assay. The interaction association among circMMP11, miR-625-5p, and ZEB2 was confirmed by RNA pull-down and dual-luciferase report assays. A xenograft experiment was established to clarify the role of circMMP11 silencing in vivo.
We found that circMMP11 and ZEB2 were overexpressed in BC tissues and cells compared with controls. The suppression of circMMP11 or ZEB2 repressed proliferation, migration, and invasion while induced apoptosis of BC cells. Additionally, miR-625-5p, interacted with ZEB2, was a target of circMMP11 in BC cells. CircMMP11 regulated the expression of ZEB2 by targeting miR-625-5p. Knockdown of circMMP11-mediated effects on BC cells could be abolished by overexpression of ZEB2. Consistently, silencing of circMMP11 impeded the tumor growth in vivo.
CircMMP11/miR-625-5p/ZEB2 axis affected proliferation, migration, invasion, and apoptosis of BC cells through the mechanism of competing endogenous RNAs (ceRNA), indicating that circMMP11 was an oncogenic circRNA in BC.
环状RNA（circRNAs）已被证明在包括乳腺癌（BC）在内的肿瘤发生过程中调节基因表达方面发挥重要作用。本研究旨在探讨circMMP11在BC中的作用及潜在分子机制。
采用实时定量聚合酶链反应（RT-qPCR）检测circMMP11、微小RNA-625-5p（miR-625-5p）和锌指E盒结合同源框2（ZEB2）的表达。通过蛋白质印迹法评估ZEB2、波形蛋白和E-钙黏蛋白的蛋白表达。采用3-(4,5-二甲基噻唑-2-基)-2,5-二苯基-2H-四唑溴盐（MTT）和集落形成试验测定BC细胞的增殖能力。用Transwell试验检测BC细胞的迁移和侵袭能力。通过流式细胞术检测凋亡细胞。通过RNA下拉和双荧光素酶报告试验证实circMMP11、miR-625-5p和ZEB2之间的相互作用关系。建立异种移植实验以阐明circMMP11沉默在体内的作用。
我们发现与对照组相比，circMMP11和ZEB2在BC组织和细胞中过表达。circMMP11或ZEB2的抑制可抑制BC细胞的增殖、迁移和侵袭，并诱导其凋亡。此外，与ZEB2相互作用的miR-625-5p是BC细胞中circMMP11的靶标。circMMP11通过靶向miR-625-5p调节ZEB2的表达。ZEB2的过表达可消除circMMP11敲低介导的对BC细胞的影响。同样，circMMP11的沉默在体内抑制肿瘤生长。
CircMMP11/miR-625-5p/ZEB2轴通过竞争性内源RNA（ceRNA）机制影响BC细胞的增殖、迁移、侵袭和凋亡，表明circMMP11是BC中的一种致癌circRNA。
