Circ_0003998 enhances doxorubicin resistance in hepatocellular carcinoma by regulating miR-218-5p/EIF5A2 pathway

Xiaomin Li,Haichao Zhao,Jiefeng He,Haoliang Zhao,Xiaojing Ren

doi:10.1186/s13000-020-01056-1

Abstract

BackgroundThe involvement of circular RNAs (circRNAs) in chemoresistance of tumors has been identified. Herein, this study aims to investigate the role and the underlying mechanism of circ_0003998 in doxorubicin (DOX) resistance in hepatocellular carcinoma (HCC).MethodsThe expression of circ_0003998 and microRNA (miR)-218-5p and eukaryotic translation initiation factor 5A-2 (EIF5A2) mRNA was detected using quantitative real-time polymerase chain reaction. Cell viability, migration and invasion were analyzed using cell counting kit-8, colony formation and transwell assay, respectively. The levels of matrix metallopeptidase 9 (MMP-9), E-cadherin, Vimentin, N-cadherin and EIF5A2 protein were detected using western blot. The interaction between miR-218-5p and circ_0003998 or EIF5A2 was confirmed by dual-luciferase reporter assay. In vivo experiments were performed using murine xenograft models.ResultsCirc_0003998 was elevated in HCC tissues, DOX-resistant tissues and cells, and circ_0003998 knockdown promoted DOX-sensitivity in HCC by inhibiting resistant cell viability, migration, invasion and EMT in vitro and enhanced DOX cytotoxicity in vivo. Bioinformatics analysis revealed circ_0003998 inhibited miR-218-5p expression, which was clarified to be a target of circ_0003998, and circ_0003998 knockdown sensitized HCC cell to DOX by sponging miR-218-5p. EIF5A2 was a target of miR-218-5p, and miR-218-5p mitigated DOX resistance in HCC cells through modulating EIF5A2 expression. Additionally, circ_0003998 served as a competing endogenous RNA for miR-218-5p to regulate EIF5A2 expression.ConclusionCirc_0003998 knockdown sensitized HCC cell to DOX by regulating miR-218-5p/EIF5A2 axis, indicating new markers of poor response to DOX and potential therapeutic strategies for the chemotherapy of HCC.

Highlights

Hepatocellular carcinoma (HCC), as one of the most common global leading causes of cancer-related mortality, is an invasive malignant tumor and severely threaten human health [1]
Circ_0003998 and eukaryotic translation initiation factor 5A-2 (EIF5A2) are elevated, while miR218-5p is decreased in hepatocellular carcinoma (HCC) tissues and DOXresistant HCC cell lines
QRT-PCR analysis showed by contrast with normal hepatocyte THLE-2, circ_0003998 was increased in HCC cell lines Hep3B, Huh7 and HCCLM3 (Fig. 1b)

Summary

Introduction

Hepatocellular carcinoma (HCC), as one of the most common global leading causes of cancer-related mortality, is an invasive malignant tumor and severely threaten human health [1]. Doxorubicin (DOX) is one kind of anthracycline-based chemotherapeutic agent that suppresses DNA/RNA synthesis trough intercalation between base pairs of DNA strands, leading to cancer cells apoptosis [4]. DOX is a first-line chemotherapy strategy for transarterial chemoembolization (TACE), a most commonly used treatment for most advanced HCC [5, 6]. DOX resistance gradually emerged in HCC patients to limit the effects of the drug [7]. Better understanding on the mechanisms of DOX resistance in HCC is of great significance. This study aims to investigate the role and the underlying mechanism of circ_0003998 in doxorubicin (DOX) resistance in hepatocellular carcinoma (HCC)

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Conclusion