HBX 41108

[Exogenous HBx promotes epithelial-mesenchymal transition of hepatic progenitor cells in Kunming mice].[Pubmed:28274311]

Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi. 2017 Mar;33(3):331-336.

Objective To construct an animal model in which hepatitis B virus X protein (HBx) directly affect hepatic progenitor cells (HPCs), and investigate the potential mechanisms underlying epithelial-mesenchymal transition (EMT) of HPCs. Methods Kunming mice were given 2 mL/L carbon tetrachloride (CCL4) in oil solution by gavage twice a week. Four weeks later, HPCs transfected with recombinant lentiviral vectors stably expressing HBx gene as well as empty vectors were separately injected into the mice via the portal vein, and at the same time, the mice underwent a partial hepatectomy. The gavage twice a week continued after the operation. And on days 3, 5, 7, 14, 21 28 postoperation, the mice were sacrificed and the livers were removed. Fluorescence quantitative PCR was used to detect the mRNA expression level of HBx; immunohistochemistry was performed to observe the exogenous cell survival in vivo. The expression levels of E-cadherin, N-cadherin, vimentin and CK18 were assessed by fluorescence quantitative PCR and Western blotting. Results Immunohistochemistry showed that the exogenous cells obviously survived in vivo in the postoperative liver tissues. Moreover, the expression of HBx was enhanced and expanded over time. Fluorescence quantitative PCR and Western blotting showed that overexpressed HBx downregulated the expressions of E-cadherin and CK18, while upregulated the expressions of N-cadherin and vimentin. Conclusion HBx plays an important role in the regulation of EMT of HPCs in vivo.

Integrated analysis of microRNA and mRNA expression profiles in HBx-expressing hepatic cells.[Pubmed:28348484]

World J Gastroenterol. 2017 Mar 14;23(10):1787-1795.

AIM: To identify the miRNA-mRNA regulatory network in hepatitis B virus X (HBx)-expressing hepatic cells. METHODS: A stable HBx-expressing human liver cell line L02 was established. The mRNA and miRNA expression profiles of L02/HBx and L02/pcDNA liver cells were identified by RNA-sequencing analysis. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis was performed to investigate the function of candidate biomarkers, and the relationship between miRNA and mRNA was studied by network analysis. RESULTS: Compared with L02/pcDNA cells, 742 unregulated genes and 501 downregulated genes were determined as differentially expressed in L02/HBx cells. Gene ontology analysis suggested that the differentially expressed genes were relevant to different biological processes. Concurrently, 22 differential miRNAs were also determined in L02/HBx cells. Furthermore, integrated analysis of miRNA and mRNA expression profiles identified a core miRNA-mRNA regulatory network that is correlated with the carcinogenic role of HBx. CONCLUSION: Collectively, the miRNA-mRNA network-based analysis could be useful to elucidate the potential role of HBx in liver cell malignant transformation and shed light on the underlying molecular mechanism and novel therapy targets for hepatocellular carcinoma.

HBx represses RIZ1 expression by DNA methyltransferase 1 involvement in decreased miR-152 in hepatocellular carcinoma.[Pubmed:28339081]

Oncol Rep. 2017 May;37(5):2811-2818.

Hepatitis B virus (HBV) is mainly suspected to promote hepatocellular carcinoma (HCC) development by epigenetic alteration. The HBV X protein (HBx) plays a key role in the molecular pathogenesis of HBV-related HCC. However, the mechanism of HBx-mediated hepatocarcinogenesis remains to be elucidated. RIZ1 gene, a candidate HCC suppressor gene, is frequently found to be hypermethylated and downregulated in HCC. In the present study, we show that the expression of RIZ1 was downregulated in 65% HCC tissues. Decreased expression of RIZ1 was restored by 5'-Aza in MHCC-97H HCC cell lines. HBx recombinant transfection increased DNMT1 expression level and suppressed RIZ1 expression. Moreover, knockdown of DNMT1 by siRNA restored RIZ1 expression in HCC cell SMMC-7721 and reduced methylated CpG sites of RIZ1. ChIP results showed that DNMT1 protein could bind to RIZ1 promoter, and this interaction was further enhanced with the transfected HBX recombinant. Moreover, miR-152 was decreased and involved in upregulation of DNMT1 in HBx transfected cells, at least partly, contributed to the epigenetic inactivation of RIZ1. Taken together, our data found that HBx repressed RIZ1 expression via DNMT1, which offered a new mechanism of RIZ1 inactivation in HCC, except for the widely known DNA methylation. These results enriched the epigenetic mechanism by which HBx contributes to pathogenesis of HBV-HCC.

Synthesis and biological evaluation of 9-oxo-9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile analogues as potential inhibitors of deubiquitinating enzymes.[Pubmed:20186914]

ChemMedChem. 2010 Apr 6;5(4):552-8.

High-throughput screening highlighted 9-oxo-9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile (1) as an active inhibitor of ubiquitin-specific proteases (USPs), a family of hydrolytic enzymes involved in the removal of ubiquitin from protein substrates. The chemical behavior of compound 1 was examined. Moreover, the synthesis and in vitro evaluation of new compounds, analogues of 1, led to the identification of potent and selective inhibitors of the deubiquitinating enzyme USP8.

Small-molecule inhibitor of USP7/HAUSP ubiquitin protease stabilizes and activates p53 in cells.[Pubmed:19671755]

Mol Cancer Ther. 2009 Aug;8(8):2286-95.

Deregulation of the ubiquitin/proteasome system has been implicated in the pathogenesis of many human diseases, including cancer. Ubiquitin-specific proteases (USP) are cysteine proteases involved in the deubiquitination of protein substrates. Functional connections between USP7 and essential viral proteins and oncogenic pathways, such as the p53/Mdm2 and phosphatidylinositol 3-kinase/protein kinase B networks, strongly suggest that the targeting of USP7 with small-molecule inhibitors may be useful for the treatment of cancers and viral diseases. Using high-throughput screening, we have discovered HBX 41,108, a small-molecule compound that inhibits USP7 deubiquitinating activity with an IC(50) in the submicromolar range. Kinetics data indicate an uncompetitive reversible inhibition mechanism. HBX 41,108 was shown to affect USP7-mediated p53 deubiquitination in vitro and in cells. As RNA interference-mediated USP7 silencing in cancer cells, HBX 41,108 treatment stabilized p53, activated the transcription of a p53 target gene without inducing genotoxic stress, and inhibited cancer cell growth. Finally, HBX 41,108 induced p53-dependent apoptosis as shown in p53 wild-type and null isogenic cancer cell lines. We thus report the identification of the first lead-like inhibitor against USP7, providing a structural basis for the development of new anticancer drugs.