Chen Zhuo, Wang Fang, Xiong Youyi, Wang Nan, Gu Yuanting, Qiu Xinguang
Department of Breast Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000 China.
Department of Thyroid Surgery, The First Affiliated Hospital of Zhengzhou University, No.1 Jianshe East Road, Erqi District, Zhengzhou, 450000 Henan China.
Cancer Cell Int. 2020 Aug 18;20:400. doi: 10.1186/s12935-020-01492-5. eCollection 2020.
Breast cancer (BC) is the most common malignancy among women. Emerging studies have demonstrated that circular RNA (circRNA) zinc finger RNA binding protein (circZFR) serves as a crucial regulator in many human cancers. However, the role and mechanism of circZFR in BC tumorigenesis remain unclear.
The levels of circZFR, miR-578 and hypoxia-inducible factor 1α (HIF1A) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Cell viability, colony formation, apoptosis, migration and invasion capacities in vitro were determined by using the Cell Counting Kit-8 (CCK-8), standard colony formation, flow cytometry and transwell assays, respectively. Glucose uptake, lactate product and adenosine triphosphate (ATP) levels of cells in vitro were measured using the commercial human assay kits. Targeted relationships among circZFR, miR-578 and HIF1A in BC cell lines were verified by dual-luciferase reporter and RNA pulldown assays. Animal studies were performed to assess the effect of circZFR on tumor growth in vivo.
Our data indicated that circZFR was overexpressed in BC tissues and cells, and the increased circZFR level predicted poor prognosis of BC patients. CircZFR silencing or miR-578 overexpression repressed BC cell viability, colony formation, migration, invasion, and glycolysis and enhanced cell apoptosis in vitro. CircZFR silencing also hampered tumor growth in vivo. Mechanistically, circZFR acted as a sponge of miR-578, and circZFR silencing hindered BC cell malignant behaviors by miR-578. HIF1A was a functional target of miR-578 in regulating BC cell viability, colony formation, migration, invasion, glycolysis and apoptosis in vitro. Furthermore, circZFR modulated HIF1A expression through sponging miR-578.
Our findings first identified that the silencing of circZFR suppressed BC malignant progression in vitro via the regulation of the miR-578/HIF1A axis, providing evidence for the crucial involvement of circZFR in BC pathogenesis.
乳腺癌（BC）是女性中最常见的恶性肿瘤。新兴研究表明，环状RNA（circRNA）锌指RNA结合蛋白（circZFR）在许多人类癌症中起着关键调节作用。然而，circZFR在BC肿瘤发生中的作用和机制仍不清楚。
通过定量实时聚合酶链反应（qRT-PCR）或蛋白质免疫印迹法检测circZFR、miR-578和缺氧诱导因子1α（HIF1A）的水平。分别使用细胞计数试剂盒-8（CCK-8）、标准集落形成、流式细胞术和Transwell实验测定体外细胞活力、集落形成、凋亡、迁移和侵袭能力。使用商业化的人体检测试剂盒测量体外细胞的葡萄糖摄取、乳酸生成和三磷酸腺苷（ATP）水平。通过双荧光素酶报告基因和RNA下拉实验验证BC细胞系中circZFR、miR-578和HIF1A之间的靶向关系。进行动物研究以评估circZFR对体内肿瘤生长的影响。
我们的数据表明，circZFR在BC组织和细胞中过表达，circZFR水平升高预示着BC患者预后不良。circZFR沉默或miR-578过表达可抑制BC细胞活力、集落形成、迁移、侵袭和糖酵解，并增强体外细胞凋亡。circZFR沉默也会阻碍体内肿瘤生长。从机制上讲，circZFR作为miR-578的海绵，circZFR沉默通过miR-578阻碍BC细胞的恶性行为。HIF1A是miR-578在体外调节BC细胞活力、集落形成、迁移、侵袭、糖酵解和凋亡中的功能靶点。此外，circZFR通过结合miR-578调节HIF1A表达。
我们的研究首次发现，circZFR的沉默通过调节miR-578/HIF1A轴在体外抑制BC的恶性进展，为circZFR参与BC发病机制提供了证据。
