Thymosin-β4 Mediates Hepatic Stellate Cell Activation by Interfering with CircRNA-0067835/miR-155/FoxO3 Signaling Pathway

Background/Aims: Hepatic stellate cells (HSCs) are the primary cell type responsible for liver fibrosis. Our study proved that thymosin beta 4 (Tβ4) has anti-fibrogenic effects in HSCs through PI3K/AKT pathway. However, the underlying mechanisms are not fully elucidated. Circular RNAs (circRNAs) play important roles in fine-tuning gene expression and are often deregulated in cancers. However, the expression profile and clinical significance of in liver fibrosis is still unknown. Therefore, we hypothesize that Tβ4 influences circRNAs in liver fibrosis. Methods: Circular RNA microarray was conducted to identify Tβ4-related circRNAs. Pathway analysis and miRNA response elements analysis was conducted to predict the potential roles of differentially expressed circRNAs in liver fibrosis. CCK8 assays and flow cytometric assays were conducted to clarify the role of circRNA in liver fibrosis. Bioinformatics analysis and in vitro experiments were conducted to clarify the mechanism of circRNA-mediated gene regulation in liver fibrosis. Results: A total of 644 differentially expressed circRNAs were identified between the Tβ4-depleted LX-2 cells and the control LX2 cells. The expression of circRNA-0067835 was significantly increased in the Tβ4-depleted LX-2 cells compared with control. Knockdown of circRNA-0067835 observably decreased LX-2 cell proliferation by causing G1 arrest and promoting apoptosis. Bioinformatics online programs predicted that circRNA-0067835 acted as miR-155 sponge to regulate FOXO3a expression, which was validated using luciferase reporter assay. Conclusion: Our experiments showed that circRNA-0067835 regulated liver fibrosis progression by acting as a sponge of miR-155 to promote FOXO3a expression, indicating that circRNA-0067835 may serve as a potential therapeutic target for patients with liver fibrosis.