Jiang Bin, Tian Maolin, Li Gang, Sadula Abuduhaibaier, Xiu Dianrong, Yuan Chunhui, Bing Yuntao
Department of General Surgery, Peking University Third Hospital, Beijing, China.
Front Genet. 2022 Feb 8;13:804848. doi: 10.3389/fgene.2022.804848. eCollection 2022.
Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. Recent evidence has shown that circular RNAs (circRNAs) play important roles in tissue development, gene transcription, signal regulation and tumorigenesis. However, whether circRNAs are involved in HCC progression and encode functional proteins remains largely unknown. In the present study, we aimed to explore the function and molecular mechanism of circRNAs in HCC. First, many circRNAs were found to be differentially expressed in HCC samples and paired adjacent normal liver tissues. The validation of dysregulated circRNAs by qRT-PCR revealed that circEPS15 expression was downregulated in HCC tissues, and the survival curves showed that low circEPS15 levels were associated with poor overall survival in HCC patients. Then, the overexpression of circEPS15 suppressed tumor cell invasion and migration by inhibiting the TJP1/CDH2/VIM signaling pathway and retarded cell cycle progression, which was confirmed by the Transwell culture system, wound healing assays, flow cytometry and western blot assays. After that, the spanning junction open reading frame in circEPS15 driven by IRES was shown to encode a novel protein, which was verified by western blotting with full-length, mutated, and truncated sequences of circEPS15 with a FLAG tag. Moreover, ceRNA analysis and qRT-PCR results suggest a possible circRNA (circEPS15)-miRNA-mRNA network in HCC. Collectively, our study reveals that endogenous circEPS15 plays a novel role in repressing HCC through the ceRNA network and encodes a functional protein.
肝细胞癌（HCC）是全球癌症相关死亡的主要原因之一。最近的证据表明，环状RNA（circRNAs）在组织发育、基因转录、信号调节和肿瘤发生中发挥重要作用。然而，circRNAs是否参与HCC进展并编码功能蛋白仍 largely未知。在本研究中，我们旨在探索circRNAs在HCC中的功能和分子机制。首先，发现许多circRNAs在HCC样本和配对的相邻正常肝组织中差异表达。通过qRT-PCR对失调的circRNAs进行验证，结果显示circEPS15在HCC组织中表达下调，生存曲线表明低circEPS15水平与HCC患者的总体生存率差相关。然后，circEPS15的过表达通过抑制TJP1/CDH2/VIM信号通路抑制肿瘤细胞侵袭和迁移，并延缓细胞周期进程，这通过Transwell培养系统、伤口愈合试验、流式细胞术和蛋白质印迹试验得到证实。之后，由IRES驱动的circEPS15中的跨接开放阅读框被证明编码一种新蛋白，这通过用带有FLAG标签的circEPS15的全长、突变和截短序列进行蛋白质印迹得到验证。此外，ceRNA分析和qRT-PCR结果提示HCC中可能存在circRNA（circEPS15）-miRNA-mRNA网络。总之，我们的研究表明内源性circEPS15通过ceRNA网络在抑制HCC中发挥新作用并编码一种功能蛋白。
