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Circular RNAs (circRNAs) are a class of regulatory RNAs with complex roles in healthy and diseased tissues. However, the oncogenic role of circRNAs in hepatocellular carcinoma (HCC) remains poorly understood, including the mechanisms by which the circular ubiquitin-binding associated protein 2 (circUBAP2) contributes to tumorigenesis. We analyzed the expression of circUBAP2 in 20 paired samples of HCC and healthy tissue as well as in seven HCC cell lines via quantitative real-time polymerase chain reaction. Functional experiments, such as CCK8 viability assays, colony formation assays, wound healing, transwell assays and flow cytometry, were conducted to assess the effects of circUBAP2 in vitro. To further elucidate the mechanisms by which circUBAP2 acts, we conducted dual-luciferase assays, western blots, RNA pull-down assays and rescue experiments. CircUBAP2 was highly upregulated in most HCC tissues and was associated with poor prognosis. HCC patients with high circUBAP2 expression had greater vascular invasion and worse differentiation. Functionally, circUBAP2 overexpression enhanced HCC cell proliferation, migration and invasion and inhibited apoptosis. Furthermore, we found that circUBAP2 upregulated c-Myc expression by sponging miR-1294, thus contributing to hepatocarcinogenesis. Inhibiting circUBAP2 expression in HCC attenuated the oncogenic effects of c-Myc. These findings suggest that circUBAP2 promotes HCC growth and metastasis. CircUBAP2 may have value as an independent prognostic biomarker or as a new target for the treatment of HCC. [ABSTRACT FROM AUTHOR]

Background & Aims: Hepatocellular carcinoma (HCC) is a fatal disease characterized by vast molecular heterogeneity. Although major advances in tumour genetics has led to the identification of new biomarkers, the prognosis of patients with HCC remains dismal. Methods: Quantitative reverse‐transcription polymerase chain reaction (qRT‐PCR) and western blot (WB) were used to evaluate meiosis‐specific nuclear structural 1 (MNS1) expression in HCC cells. Immunohistochemistry staining was used to evaluate MNS1 expression in HCC tissues. Clinical significance of MNS1 was evaluated by Cox regression analysis. Transwell assays were conducted to assess cells migration ability. Cell counting kit‐8 and colony formation assays were performed to detect cells proliferation ability. NOD/SCID/γc(null) (NOG) mice model was adopted to investigate functions of MNS1 in vivo. Results: The expression of MNS1, which is elevated in most HCC tissues, correlated with poor survival in HCC patients. Functional experiments revealed the oncogenic role of MNS1, which promotes HCC growth and metastasis through AKT‐dependent modulation of β‐catenin. β‐Catenin expression was crucial for MNS1's oncogenic effects. MNS1 indirectly translocated β‐catenin from the cytoplasm to the nucleus via the MNS1‐GSK3β axis. Conclusions: MNS1 promotes HCC growth and metastasis via activating PI3K/AKT signalling and may serve as an important prognostic biomarker as well as potential novel therapeutic target for HCC. [ABSTRACT FROM AUTHOR]

Hepatitis C virus (HCV) infection is a major cause of severe liver disease. Interferon (IFN)/ribavirin treatment remains the standard therapeutic regimen for HCV infection in most countries. IFN-stimulated genes are believed to contribute to antiviral effects. However, emerging evidence suggests that microRNAs (miRNAs), a class of noncoding small RNAs, are involved in the control of viral infection. Here, we systematically profiled the hepatocyte expression of a set of 750 miRNAs in response to alpha interferon (IFN-) and interleukin-28B (IL-28B) treatments. The anti-HCV activity of differentially expressed miRNAs was evaluated using cell culture-derived HCV in vitro. The results demonstrate that let-7b had a significant anti-HCV effect by inhibiting HCV replication and viral protein translation in human hepatoma cells. In particular, we show that the inhibition of let-7b attenuated the anti-HCV effects of IFN- and IL-28B. Furthermore, we show that the host factor insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) is a target of let-7b. IGF2BP1 was required for HCV replication, and its expression was downregulated by IFN- and IL-28B. Deletion of the wild-type seed region of let-7b abolished its antiviral activity. Finally, we demonstrate that other let-7 family miRNAs were able to inhibit HCV and to suppress IGF2BP1 expression. In conclusion, we provide an example of a host miRNA regulated by type I and type III IFNs that inhibits HCV replication and infectivity by targeting host targets. These results highlight the important role of miRNAs in the host antiviral immune response and provide a novel candidate for anti-HCV therapy. [ABSTRACT FROM AUTHOR]

Abstract: The epidermal growth factor receptor (EGFR) is overexpressed in many epithelial tumors and plays an important role in the tumorigenesis of these tumors. Inhibitors of EGFR reduce the proliferation rate of cancers and are promising therapeutic agents of cancers. Recently, two studies have identified somatic mutations in the exons 18–21 of EGFR that were strongly correlated with robust clinical response to gefitinib treatment in patients with non-small cell lung cancer. To investigate whether EGFR mutation is involved in the tumorigenesis of hepatocellular carcinoma (HCC), we performed direct sequencing of exons 18–21 on 89 HCCs. No mutations causing amino acid changes or deletions were identified. The results indicate mutation of the kinase domain of EGFR does not play a significant role in the tumorigenesis of HCC and gefitinib is unlikely to be used as single-drug therapy for HCC. [Copyright &y& Elsevier]

Liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC) are commonly induced by chronic hepatitis C virus (HCV) infection. We aimed to identify and characterize the involvement of previously screened cytokine GDF15 in HCV pathogenesis. We examined the GDF15 expression after HCV infection both in vitro and in vivo. Cultured JFH-1 HCV was used to determine the GDF15 function on virus propagation. GDF15 overexpression and RNA interference were employed to profile the GDF15-regulated genes, signaling pathways and cell biology phenotypes. The mRNA expression and protein secretion of GDF15 was dramatically increased in HCV-infected hepatoma cells, which maybe a host response to viral proteins or infection-induced cell stress. Patients infected with HCV had an average 15-fold higher blood GDF15 level than that of healthy volunteers. Three HCC individuals in the HCV cohort showed extremely high GDF15 concentrations. Transfection or exogenously supplied GDF15 enhanced HCV propagation, whereas knockdown of endogenous GDF15 resulted in inhibition of virus replication. Overexpressed GDF15 led to Akt activation and the phosphorylation of Akt downstream targeted GSK-3b and Raf. Several HCC-related molecules, such as E-cadherin, b-catenin, Cyclin A2/B1/D1, were up-regulated by GDF15 stimulation in vitro. Overexpression of GDF15 in hepatoma cells resulted in increased DNA synthesis, promoted cell proliferation, and importantly enhanced invasiveness of the cells. In conclusion, these results suggest that an elevated serum GDF15 level is a potential diagnostic marker for viral hepatitis, and GDF15 may contribute to HCV pathogenesis by altering the signaling and growth of host cells. [ABSTRACT FROM AUTHOR]

Previous research suggests that far upstream element-binding protein 1 (FUBP1) plays an important role in various tumors including epatocellular carcinoma (HCC). However, the role of FUBP1 in liver cancer remains controversial, and the regulatory pathway by FUBP1 awaits to be determined. This study aims to identify the role of FUBP1 in HCC progression. Our result shows that the high level of FUBP1 expression in HCC predicts poor prognosis after surgery. Overexpression of FUBP1 promotes HCC proliferation, invasion, and metastasis by activating transforming growth factor-β (TGF-β)/Smad pathway and enhancing epithelial-mesenchymal transition (EMT) in vitro and in vivo. Inhibitor of Thrombospondin-1 (LSKL) could inhibit HCC proliferation and invasion in vitro and in vivo by blocking the activation of TGF-β/Smad pathway mediated by thrombospondin-1 (THBS1). Our study identified the critical role of FUBP1-THBS1-TGF-β signaling axis in HCC and provides potentially new therapeutic modalities in HCC. [ABSTRACT FROM AUTHOR]