Department of Breast Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China.
Department of Breast Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China.
Int J Biochem Cell Biol. 2020 Sep;126:105798. doi: 10.1016/j.biocel.2020.105798. Epub 2020 Jul 3.
Circular RNAs (circRNAs) play an important role in tumor development. The miRNA sponge is a common role played by circRNAs in various tumors, including breast cancer.
This study aimed to explore the role of circ-ZEB1 in the proliferation and apoptosis of triple negative breast cancer (TNBC) cells.
The expressions of several circRNAs which were predicted to be bound with miR-448 were detected in 30 clinical TNBC tumor tissues and paired paracancer tissues. The cell counting kit-8 assay was performed to detect the TNBC cell proliferation. The TNBC cell apoptosis was detected using the TUNEL assay. The binding between circ-ZEB1 and miR-448, as well as between miR-448 and eukaryotic elongation factor 2 kinase (eEF2 K), was detected using the RNA pull-down assay and/or the luciferase reporter assay. The effect of circ-ZEB1 knockdown on TNBC tumor growth was detected using the mouse xenograft model.
Compared with normal tissues and breast epithelial cells, the expression of circ-ZEB1 was markedly higher in TNBC tumor tissues and tumor cell lines. The small hairpin RNA-mediated circ-ZEB1 knockdown inhibited TNBC cell proliferation and induced cell apoptosis. The RNA pull-down assay and the luciferase reporter assay confirmed the binding between circ-ZEB1 and miR-448, as well as between miR-448 and eEF2 K. The knockdown of circ-ZEB1 was proven to inhibit TNBC cell proliferation and tumor growth via releasing miR-448, and subsequently reducing the expression of the miR-448 target, eEF2 K.
In conclusion, our findings identified a new functional circ-ZEB1 in TNBC tumorigenesis, and revealed the important regulatory role of circ-ZEB1 via sponging miR-448, providing a novel insight for TNBC pathogenesis.
环状 RNA（circRNAs）在肿瘤发展中发挥重要作用。miRNA 海绵是 circRNAs 在包括乳腺癌在内的各种肿瘤中发挥的常见作用。
本研究旨在探讨 circ-ZEB1 在三阴性乳腺癌（TNBC）细胞增殖和凋亡中的作用。
检测了 30 例临床 TNBC 肿瘤组织和配对癌旁组织中几种被预测与 miR-448 结合的 circRNAs 的表达。使用细胞计数试剂盒-8 检测 TNBC 细胞增殖。使用 TUNEL 检测 TNBC 细胞凋亡。使用 RNA 下拉实验和/或荧光素酶报告基因实验检测 circ-ZEB1 与 miR-448 以及 miR-448 与真核延伸因子 2 激酶（eEF2K）之间的结合。使用小鼠异种移植模型检测 circ-ZEB1 敲低对 TNBC 肿瘤生长的影响。
与正常组织和乳腺上皮细胞相比，circ-ZEB1 在 TNBC 肿瘤组织和肿瘤细胞系中的表达明显升高。小发夹 RNA 介导的 circ-ZEB1 敲低抑制 TNBC 细胞增殖并诱导细胞凋亡。RNA 下拉实验和荧光素酶报告基因实验证实了 circ-ZEB1 与 miR-448 以及 miR-448 与 eEF2K 之间的结合。circ-ZEB1 的敲低通过释放 miR-448 抑制 TNBC 细胞增殖和肿瘤生长，从而降低 miR-448 靶标 eEF2K 的表达。
总之，我们的研究结果鉴定了 TNBC 肿瘤发生中的一个新的功能性 circ-ZEB1，并通过海绵吸附 miR-448 揭示了 circ-ZEB1 的重要调节作用，为 TNBC 的发病机制提供了新的见解。
