环状RNA hsa_circ_0003288通过调控肝细胞癌中的hsa_circ_0003288/miR-145/PD-L1轴诱导上皮-间质转化和侵袭。
Circular RNA hsa_circ_0003288 induces EMT and invasion by regulating hsa_circ_0003288/miR-145/PD-L1 axis in hepatocellular carcinoma.
作者信息
Xu Guili, Zhang Peng, Liang Hansi, Xu Yunhua, Shen Jian, Wang Wansheng, Li Mingming, Huang Jintao, Ni Caifang, Zhang Xueguang, Zhu Xiaoli
机构信息
Department of Interventional Radiology, First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, Jiangsu, 215006, China.
Jiangsu Institute of Clinical Immunology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, 215006, China.
出版信息
Cancer Cell Int. 2021 Apr 15;21(1):212. doi: 10.1186/s12935-021-01902-2.
BACKGROUND
Epithelial-mesenchymal transition (EMT) has been associated with wound healing, tumorigenesis, and metastasis. Circular RNAs (circRNAs) are functional non-coding RNAs involved in multiple human cancers. However, whether and how circRNAs contribute to the EMT in hepatocellular carcinomas (HCC) remains to be deciphered. In this study, we investigated the regulation and function of hsa_circ_0003288 on programmed death-1 ligand 1 (PD-L1) during EMT and HCC invasiveness.
METHODS
Hsa_circ_0003288 expression was measured by real-time quantitative reverse transcriptase PCR (qRT-PCR). Luciferase reporter assays, RNA pull-down assay and fluorescence in situ hybridization (FISH) were used to determine the correlation between hsa_circ_0003288 and miR-145 and between miR-145 and PD-L1. Furthermore, ectopic overexpression and siRNA-mediated downregulation of hsa_circ_0003288, transwell assays, and in vivo studies were used to determine the function of hsa_circ_0003288 on the EMT and invasiveness of L02 and HCC cells.
RESULTS
miR-145 directly targeted the PD-L1 3'-untranslated region (UTR) region, and hsa_circ_0003288 acted as a miR-145 sponge to regulate PD-L1 expression. Overexpression of hsa_circ_0003288 increased PD-L1 levels and promoted EMT, migration, and invasiveness of L02 cells. These observations were reversed after knockdown of hsa_circ_0003288 in HepG2 and Huh7 cells. Overexpression of PD-L1 rescued EMT, migration, and invasiveness of HepG2 and Huh7 cells after knockdown of hsa_circ_0003288. Furthermore, hsa_circ_0003288 knockdown reduced EMT in in vivo studies. Hsa_circ_0003288/PD-L1 axis was found to mediate the metastatic phenotypes via the PI3K/Akt pathway in HCC. Additionally, expression levels of hsa_circ_0003288 were increased and positively correlated with PD-L1 expression in HCC tissues.
CONCLUSION
Our findings demonstrated that hsa_circ_0003288 promoted EMT and invasion of HCC via the hsa_circ_0003288/miR-145/PD-L1 axis through the PI3K/Akt pathway. Targeting hsa_circ_0003288 may be a therapeutic strategy for the treatment of HCC.
背景
上皮-间质转化（EMT）与伤口愈合、肿瘤发生和转移有关。环状RNA（circRNA）是参与多种人类癌症的功能性非编码RNA。然而，circRNA是否以及如何在肝细胞癌（HCC）的EMT过程中发挥作用仍有待阐明。在本研究中，我们调查了hsa_circ_0003288在EMT和HCC侵袭过程中对程序性死亡-1配体1（PD-L1）的调控及功能。
方法
采用实时定量逆转录聚合酶链反应（qRT-PCR）检测hsa_circ_0003288的表达。利用荧光素酶报告基因检测、RNA下拉实验和荧光原位杂交（FISH）确定hsa_circ_0003288与miR-145以及miR-145与PD-L1之间的相关性。此外，通过异位过表达和siRNA介导的hsa_circ_0003288下调、Transwell实验和体内研究来确定hsa_circ_0003288对L02和HCC细胞的EMT和侵袭能力的作用。
结果
miR-145直接靶向PD-L1的3'-非翻译区（UTR），hsa_circ_0003288作为miR-145的海绵体来调节PD-L1的表达。hsa_circ_0003288的过表达增加了PD-L1水平，并促进了L02细胞的EMT、迁移和侵袭。在HepG2和Huh7细胞中敲低hsa_circ_0003288后，这些现象得到逆转。在敲低hsa_circ_0003288后，PD-L1的过表达挽救了HepG2和Huh7细胞的EMT、迁移和侵袭。此外，在体内研究中，hsa_circ_0003288的敲低减少了EMT。发现hsa_circ_0003288/PD-L1轴通过PI3K/Akt途径介导HCC的转移表型。此外，hsa_circ_0003288在HCC组织中的表达水平升高，且与PD-L1表达呈正相关。
结论
我们的研究结果表明，hsa_circ_0003288通过PI3K/Akt途径经由hsa_circ_0003288/miR-145/PD-L1轴促进HCC的EMT和侵袭。靶向hsa_circ_0003288可能是治疗HCC的一种治疗策略。
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