Neuroprotective Effect of Antiapoptotic URG7 Protein on Human Neuroblastoma Cell Line SH-SY5Y

Up-regulated Gene clone 7 (URG7) is a protein localized in the endoplasmic reticulum (ER) and overexpressed in liver cells upon hepatitis B virus (HBV) infection. Its activity has been related to the attenuation of ER stress resulting from HBV infection, promoting protein folding and ubiquitination and reducing cell apoptosis overall. While the antiapoptotic activity of URG7 in HBV-infected cells may have negative implications, this effect could be exploited positively in the field of proteinopathies, such as neurodegenerative diseases. In this work, we aimed to verify the possible contribution of URG7 as a reliever of cellular proteostasis alterations in a neuronal in vitro system. Following tunicamycin-induced ER stress, URG7 was shown to modulate different markers of the unfolded protein response (UPR) in favor of cell survival, mitigating ER stress and activating autophagy. Furthermore, URG7 promoted ubiquitination, and determined a reduction in protein aggregation, calcium release from the ER and intracellular ROS content, confirming its pro-survival activity. Therefore, in light of the results reported in this work, we hypothesize that URG7 offers activity as an ER stress reliever in a neuronal in vitro model, and we paved the way for a new approach in the treatment of neurodegenerative diseases.

Hepatitis B virus promotes hepatocellular carcinoma development by activating GP73 to repress the innate immune response

Background

Hepatitis B virus (HBV) causes acute and chronic infection in the clinic. Hepatocellular carcinoma (HCC) is closely linked to HBV infection. Serum Golgi protein 73 (GP73) increases during HBV infection. However, the role of GP73 during HBV infection and the occurrence of HBV-related HCC is still poorly understood.

Methods

The underlying role of HBV-induced GP73 in regulating HCC development was investigated in this study. GP73 expression in HBV-related clinical HCC tissues and in HBV-infected hepatoma cells and primary human hepatocytes was evaluated by immunohistochemistry, ELISAs, Western blotting and quantitative real-time PCR (qRT-PCR) analysis. Tumorigenicity of GP73 overexpressed cells was detected by flow cytometry, qRT-PCR, xenograft nude mouse analyses and sphere formation assays. The effects of GP73 and HBV infection on host innate immune responses in hepatocytes were further investigated by Western blotting and qRT-PCR analysis.

Results

Initially, we confirmed that HBV-positive HCC tissues had significantly higher expression of GP73. Ectopic expression of the HBV gene could induce GP73 expression in primary human hepatocytes and hepatoma cells in vitro. In addition, we discovered that GP73 promotes HCC in both normal liver cells and hepatoma cells. We also found that ectopic expression of HBV genes increases GP73 expression, suppressing the host's innate immune responses in hepatocytes.

Conclusions

Our results demonstrate that HBV facilitates HCC development by activating GP73 to repress the host's innate immune response. This study adds to our understanding of the pathogenesis of HBV infection-induced HCC. The findings also provide preclinical support for GP73 as a potential HCC prevention or treatment target.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13027-022-00462-y.

HIV-1-Mediated Acceleration of Oncovirus-Related Non-AIDS-Defining Cancers

With the advent of combination antiretroviral therapy (cART), overall survival has been improved, and the incidence of acquired immunodeficiency syndrome (AIDS)-defining cancers has also been remarkably reduced. However, non-AIDS-defining cancers among human immunodeficiency virus-1 (HIV-1)-associated malignancies have increased significantly so that cancer is the leading cause of death in people living with HIV in certain highly developed countries, such as France. However, it is currently unknown how HIV-1 infection raises oncogenic virus-mediated cancer risks in the HIV-1 and oncogenic virus co-infected patients, and thus elucidation of the molecular mechanisms for how HIV-1 expedites the oncogenic viruses-triggered tumorigenesis in the co-infected hosts is imperative for developing therapeutics to cure or impede the carcinogenesis. Hence, this review is focused on HIV-1 and oncogenic virus co-infection-mediated molecular processes in the acceleration of non-AIDS-defining cancers.

Hepatitis B x antigen (HBx) is an important therapeutic target in the pathogenesis of hepatocellular carcinoma

Hepatitis B virus (HBV) is a human pathogen that has infected an estimated two billion people worldwide. Despite the availability of highly efficacious vaccines, universal screening of the blood supply for virus, and potent direct acting anti-viral drugs, there are more than 250 million carriers of HBV who are at risk for the sequential development of hepatitis, fibrosis, cirrhosis and hepatocellular carcinoma (HCC). More than 800,000 deaths per year are attributed to chronic hepatitis B. Many different therapeutic approaches have been developed to block virus replication, and although effective, none are curative. These treatments have little or no impact upon the portions of integrated HBV DNA, which often encode the virus regulatory protein, HBx. Although given little attention, HBx is an important therapeutic target because it contributes importantly to (a) HBV replication, (b) in protecting infected cells from immune mediated destruction during chronic infection, and (c) in the development of HCC. Thus, the development of therapies targeting HBx, combined with other established therapies, will provide a functional cure that will target virus replication and further reduce or eliminate both the morbidity and mortality associated with chronic liver disease and HCC. Simultaneous targeting of all these characteristics underscores the importance of developing therapies against HBx.

Role of Wnt/β-catenin signaling pathway in occurrence and development of hepatocellular carcinoma

Studies have shown that the occurrence and development of liver cancer are related to a variety of signaling pathways. The Wnt/β-catenin signaling pathway is involved in all stages of liver disease progression, from initial liver damage to inflammation, fibrosis, and cirrhosis, as well as the occurrence and progression of tumors. Abnormal Wnt/β-catenin signaling promotes the development and progression of different liver diseases, including cancer. This review introduces the activation, biological function, and regulatory mechanism of the Wnt/β-catenin signaling pathway, discusses the role of ngthis pathway in the occurrence and progression of liver cancer, and describes factors that can inhibit the Wnt/β-catenin signaling pathway, such as small molecule inhibitors, traditional Chinese medicine extracts, and microRNAs, with an aim to provide reference for the basic and clinical research of liver cancer.

GP73 facilitates hepatitis B virus replication by repressing the NF-κB signaling pathway

Hepatitis B virus (HBV) chronically infects approximately 350 million people worldwide, and 600 000 deaths are caused by HBV-related hepatic failure. Golgi protein 73 (GP73) is a serum biomarker for liver diseases, including chronic hepatitis B. Here, we determine the effect of HBV infection on GP73 production and characterized the role of GP73 in HBV replication. Initially, we show that GP73 is highly produced in the sera of HBV-positive patients with chronic liver diseases and in HBV-stimulated leukocytes. In addition, HBV stimulation promotes GP73 production in peripheral blood mononuclear cells isolated from healthy donors and in macrophages derived from human acute monocytic leukemia cells (THP-1). Notably, the hepatitis B surface antigen (HBsAg), but not HBV replication, is required for the activation of GP73 expression. Moreover, in HepG2 cells and Huh7 cells, GP73 facilitates HBV replication and represses nuclear factor kappa B p50 expression, which in turn represses HBV replication and GP73 expression. Finally, we demonstrate that GP73 facilitates HBV replication by repressing the innate immune response and the nuclear factor kappa B signaling pathway. Taken together, we revealed a distinct positive feedback mechanism between HBV replication and GP73 production and suggest that GP73 acts as a potential antiviral target for HBV infection.

Downregulation of GSK3β and Upregulation of URG7 in Hepatitis B-Related Hepatocellular Carcinoma

: Hepatitis B virus (HBV) is the leading cause of hepatocellular carcinoma (HCC). The exact molecular contributors to the development of HBV-related HCC are not yet completely understood. Recent studies demonstrated that the deregulation of the Wnt pathway is highly associated with the development of HCC. Besides, HBV is known to have roles in the deregulation of this pathway. The present study evaluated the molecular aspects of the Wnt pathway in HBV-related HCC in liver tissue samples. Viral characterization was done by identifying the HBx mutations and the assessment of intrahepatic viral load. The expression of Wnt pathway genes was assessed using real-time PCR and methylation-specific PCR. The intrahepatic viral load was significantly higher in tumor samples than in normal tissues (P = 0.0008). Aberrant expression was observed in Wnt-1, Wnt-7a, FZD2, FZD7, β-catenin, URG7, c-Myc, SFRP5, and GSK3β, among which Wnt1, FZD2, SFRP5, Gsk3β, and URG7 were associated with HBV. HBx mutations at positions I88, L116, and I127 + F132 were associated with the decreased expression of GSK3β and overexpression of URG7 and Wnt1. Alterations in the expression level of β-catenin, as well as some mutants of HBx, were correlated with the level of c-Myc. HBV-related HCC seems to be mostly coordinated with epigenetic behaviors of HBx, such a multi-functional peptide with suppressing/trans-activating functions.

Hepatitis B Virus X Protein Induces RHAMM-Dependent Motility in Hepatocellular Carcinoma Cells via PI3K-Akt-Oct-1 Signaling

Chronic hepatitis B virus (HBV) infection is a major risk factor for the development of hepatocellular carcinoma (HCC), which represents one of the most common cancers worldwide. Recent studies suggest that HBV's protein X (HBx) plays a crucial role in HCC development and progression. Earlier, genome-wide analysis identified that the receptor for hyaluronan-mediated motility (RHAMM) represents a putative oncogene and is overexpressed in many human cancers, including HCC. However, the mechanism underlying RHAMM upregulation and its role in tumorigenesis remain unclear. Here, we show that ectopic expression of HBx activates the PI3K/Akt/Oct-1 pathway and upregulates RHAMM expression in HCC cells. HBx overexpression leads to dissociation of C/EBPβ from the RHAMM gene promoter, thereby inducing RHAMM upregulation. RHAMM knockdown attenuates HBx-induced cell migration and invasion in vitro. In mice, HBx promotes cancer cell colonization via RHAMM upregulation, resulting in enhanced metastasis. Analysis of gene expression datasets reveals that RHAMM mRNA level is upregulated in patients with HCC with poor prognosis. IMPLICATIONS: These results indicate that RHAMM expression is upregulated by HBx, a process that depends on the inhibition of C/EBPβ activity and activation of the PI3K/Akt/Oct-1 pathway. These results have several implications for the treatment of HBV-positive HCC involving upregulation of RHAMM and cancer metastasis. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/18/3/375/F1.large.jpg.

Harmonized Autophagy Versus Full-Fledged Hepatitis B Virus: Victorious or Defeated

Autophagy is a finely tuned process in the regulation of innate immunity to avoid excessive inflammatory responses and inflammasome signaling. In contrast, the results of recent studies have shown that autophagy may disease-dependently contribute to the pathogenesis of liver diseases, such as fibrosis, cirrhosis, and hepatocellular carcinoma (HCC) during hepatitis B virus (HBV) infection. HBV has learned to subvert the cell's autophagic machinery to promote its replication. Given the great impact of the autophagy mechanism on the HBV infection and HCC, recognizing these factors may be offered new hope for human intervention and treatment of chronic HBV. This review focuses on recent findings viewing the dual role of autophagy plays in the pathogenesis of HBV infected hepatocytes.

Hepatitis B Virus Molecular Epidemiology, Host-Virus Interaction, Coinfection, and Laboratory Diagnosis in the MENA Region: An Update

Hepatitis B virus (HBV) is an enveloped partial double-stranded DNA virus that can cause acute and chronic hepatitis. According to the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC), 257 million people are living with HBV. Moreover, 20,900 acute hepatitis B cases were reported in 2016. Hepatitis B is highly prevalent in the African, Western Pacific, Eastern Mediterranean, South-East Asia, and European regions, respectively. Due to the high mutational rate of HBV and lack of reverse transcriptase proofreading activity, ten different genotypes with different geographical distributions have been identified. HBV pathogenesis and severity of infection depend on several host and viral factors, particularly, the genetic variability of both the host and virus. Although HBV infection is a global health concern, there is a lack of adequate studies and reports in the Middle East and North Africa (MENA) region. Here, we provide a review on HBV epidemiology, pathogenesis, host-pathogen interactions, coinfection with selected viruses, and laboratory diagnosis, focusing on studies conducted in the MENA region to determine the current situation of the HBV infection and outline the future study areas.

Hepatitis B Virus-Associated Hepatocellular Carcinoma

Liver cancer is the fifth most common cancer worldwide in men and the ninth in women. It is also the second most common cause of cancer mortality. Hepatocellular carcinoma (HCC) is the most common type of liver cancer. About 350 million people globally are chronically infected with HBV. Chronic hepatitis B virus (HBV) infection accounts for at least 50% cases of HCC worldwide. Other non-HBV factors may increase HCC risk among persons with chronic HBV infection. Both indirect and direct mechanisms are involved in HCC oncogenesis by HBV. HCC-promoting HBV factors include long-lasting infection, high levels of HBV replication, HBV genotype, HBV integration, specific HBV mutants, and HBV-encoded oncoproteins (e.g., HBx and truncated preS2/S proteins). Recurrent liver inflammation caused by host immune responses during chronic HBV infection can lead to liver fibrosis and cirrhosis and accelerate hepatocyte turnover rate and promote accumulation of mutations. Major breakthroughs have been achieved in the prevention of HBV-associated HCC with HBV vaccines and antiviral therapies.

Modulation of Wnt signaling pathway by hepatitis B virus

Hepatitis B virus (HBV) has a global distribution and is one of the leading causes of hepatocellular carcinoma. The precise mechanism of pathogenicity of HBV-associated hepatocellular carcinoma (HCC) is not yet fully understood. Viral-related proteins are known to take control of several cellular pathways like Wnt/β-catenin, TGF-β, Raf/MAPK and ROS for the virus's own replication. This affects cellular persistence, multiplication, migration, alteration and genomic instability. The Wnt/FZD/β-catenin signaling pathway plays a significant role in the pathology and physiology of the liver and has been identified as a main factor in HCC development. The role of β-catenin is linked mainly to the canonical pathway of the signaling system. Progression of liver diseases is known to be accompanied by disturbances in β-catenin expression (mainly overexpression), with its cytoplasmic or nuclear translocation. In recent years, studies have documented that the HBV X protein and hepatitis B surface antigen (HBsAg) can act as pathogenic factors that are involved in the modulation and induction of canonical Wnt signaling pathway. In the present review we explore the interaction of HBV genome products with components of the Wnt/β-catenin signaling pathway that results in the enhancement of the pathway and leads to hepatocarcinogenesis.

HBx-induced miR-21 suppresses cell apoptosis in hepatocellular carcinoma by targeting interleukin-12

Hepatitis B virus (HBV) X protein (HBx) plays a key role in the initiation and progression of HBV infection‑induced hepatocellular carcinoma (HCC). Oncogenic microRNA-21 (miR-21) can be modulated by HBx protein in HCC. However, critical regulator genes in the pathway of HBx-induced miR-21 in HCC remain unclear. This study aimed to investigate the role of HBx-induced miR-21 in the apoptosis of HCC cells. In the study, interleukin-12 (IL-12) was demonstrated as a direct target of miR-21 by dual‑luciferase report assay, and miR-21 was highly expressed in HCC cells (HepG2 and HepG2 2.2.15) compared to L02 cells, but IL-12 was weakly expressed as detected by real-time quantitative PCR (RT-qPCR). Furthermore, miR-21 mimics, inhibitor, HBx-targeted siRNA, and the HBx overexpression vector (pHBx) were used to observe the regulatory effects of HBx-induced miR-21 via IL-12, and cell apoptosis was assessed. The results showed that overexpression of HBx resulted in the inhibition of IL-12. A high level of miR-21 resulted in a significant increase in proliferation and a decrease in IL-12 expression. Inhibition of miR-21 resulted in a significant increase in apoptosis and increased IL-12 expression. The results suggest that HCC cell apoptosis was suppressed at least partially through HBx-induced miR-21 by targeting IL-12.

Mechanisms of HBV-induced hepatocellular carcinoma

Hepatitis B virus (HBV) contributes to hepatocellular carcinoma (HCC) development through direct and indirect mechanisms. HBV DNA integration into the host genome occurs at early steps of clonal tumor expansion and induces both genomic instability and direct insertional mutagenesis of diverse cancer-related genes. Prolonged expression of the viral regulatory protein HBx and/or altered versions of the preS/S envelope proteins dysregulates cell transcription and proliferation control and sensitizes liver cells to carcinogenic factors. Accumulation of preS1 large envelope proteins and/or preS2/S mutant proteins activates the unfold proteins response, that can contribute to hepatocyte transformation. Epigenetic changes targeting the expression of tumor suppressor genes occur early in the development of HCC. A major role is played by the HBV protein, HBx, which is recruited on cellular chromatin and modulates chromatin dynamics at specific gene loci. Compared with tumors associated with other risk factors, HBV-related tumors have a higher rate of chromosomal alterations, p53 inactivation by mutations and overexpression of fetal liver/hepatic progenitor cells genes. The WNT/β-catenin pathway is also often activated but HBV-related tumors display a low rate of activating β-catenin mutations. HBV-related HCCs may arise on non-cirrhotic livers, further supporting the notion that HBV plays a direct role in liver transformation by triggering both common and etiology specific oncogenic pathways in addition to stimulating the host immune response and driving liver chronic necro-inflammation.

IL-6 Plays a Crucial Role in HBV Infection

Interleukin-6 (IL-6), a cytokine mainly produced by activated monocytes, has broad pleiotropic actions that affect the functions of a variety of lymphoid cells. The roles of IL-6 in regulating immunity to infections are currently being defined. Remarkably, IL-6-mediated cellular and humoral immune responses play a crucial role in determining the outcome of viral infection. This article reviews the current knowledge on the critical role of IL-6 in hepatitis B virus (HBV) infection. As a competent intermediary, IL-6 derived from activated monocytes plays an important role in promoting lymphocytes responses that are essential for effective viral control. However, as a mediator of inflammation, IL-6 is also involved in the development of HBV-induced liver cirrhosis and exacerbating liver injury. Overall, the current data point to IL-6 as an immunoregulatory cytokine in HBV infection. Immunotherapeutic strategies aimed at optimizing the beneficial effects of IL-6 in HBV infection may prove to be an ordeal in the future, as they should foster the strengths of IL-6 while circumventing potential drawbacks.

Potential mechanisms of hepatitis B virus induced liver injury

Chronic active hepatitis (CAH) is acknowledged as an imperative risk factor for the development of liver injury and hepatocellular carcinoma. The histological end points of CAH are chronic inflammation, fibrosis and cirrhosis which are coupled with increased DNA synthesis in cirrhotic vs healthy normal livers. The potential mechanism involved in CAH includes a combination of processes leading to liver cell necrosis, inflammation and cytokine production and liver scaring (fibrosis). The severity of liver damage is regulated by Hepatitis B virus genotypes and viral components. The viral and cellular factors that contribute to liver injury are discussed in this article. Liver injury caused by the viral infection affects many cellular processes such as cell signaling, apoptosis, transcription, DNA repair which in turn induce radical effects on cell survival, growth, transformation and maintenance. The consequence of such perturbations is resulted in the alteration of bile secretion, gluconeogenesis, glycolysis, detoxification and metabolism of carbohydrates, proteins, fat and balance of nutrients. The identification and elucidation of the molecular pathways perturbed by the viral proteins are important in order to design effective strategy to minimize and/or restore the hepatocytes injury.

Hepatitis B virus X protein promotes hepatocellular carcinoma transformation through interleukin-6 activation of microRNA-21 expression

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and chronic hepatitis B virus (HBV) infection is the major risk factor of HCC. The virus encodes HBV X (HBx) protein that plays a critical role in the development of HCC. Studies have revealed numerous HBx-altered genes and signalling pathways that heavily contribute to tumourigenesis of non-tumour hepatocytes. However, the role of HBx in regulating other critical gene regulators such as microRNAs is poorly understood, which impedes the exploration of a complete HBx-associated carcinogenic network. Besides, critical microRNAs that drive the transformation of non-tumour hepatocytes are yet to be identified. Here, we overexpressed C-terminal truncated HBx protein in a non-tumour hepatocyte cell line MIHA, and measured a panel of cancer-associated miRNAs. We observed that oncogenic miR-21 was upregulated upon ectopic expression of this viral protein variant. HBx-miR-21 pathway was prevalent in HCC cells as inhibition of HBx in Hep3B and PLC/PRF/5 cells significantly suppressed miR-21 expression. Subsequently, we showed that the upregulation of miR-21 was mediated by HBx-induced interleukin-6 pathway followed by activation of STAT3 transcriptional factor. The high dependency of miR-21 expression to HBx protein suggested a unique viral oncogenic pathway that could aberrantly affect a network of gene expression. Importantly, miR-21 was essential in the HBx-induced transformation of non-tumour hepatocytes. Inhibition of miR-21 effectively attenuated anchorage-independent colony formation and subcutaneous tumour growth of MIHA cells. Our study suggested that overexpression of miR-21 was critical to promote early carcinogenesis of hepatocytes upon HBV infection.

Live-cell topology assessment of URG7, MRP6₁₀₂ and SP-C using glycosylatable green fluorescent protein in mammalian cells

Experimental tools to determine membrane topology of a protein are rather limited in higher eukaryotic organisms. Here, we report the use of glycosylatable GFP (gGFP) as a sensitive and versatile membrane topology reporter in mammalian cells. gGFP selectively loses its fluorescence upon N-linked glycosylation in the ER lumen. Thus, positive fluorescence signal assigns location of gGFP to the cytosol whereas no fluorescence signal and a glycosylated status of gGFP map the location of gGFP to the ER lumen. By using mammalian gGFP, the membrane topology of disease-associated membrane proteins, URG7, MRP6102, SP-C(Val) and SP-C(Leu) was confirmed. URG7 is partially targeted to the ER, and inserted in Cin form. MRP6102 and SP-C(Leu/Val) are inserted into the membrane in Cout form. A minor population of untargeted SP-C is removed by proteasome dependent quality control system.

The pathogenesis of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common and deadly malignancies worldwide. The multikinase inhibitor sorafenib still remains the only approved agent for advanced HCC. In most cases, HCC develops based on advanced liver cirrhosis, whereas the underlying risk factors can be identified in the vast majority of patients.

METHODS

Here, we summarise and review the pathomechanisms in dependence of the underlying disease, gene signatures and frequent mutations in HCC.

RESULTS

Worldwide, HCC is most commonly caused by viral hepatitis B and C. It is less frequently associated with chronic exposure to toxins or hereditary liver diseases. Non-alcoholic fatty liver disease is an emerging risk factor with increasing prevalence nowadays. Emerging innovative technologies including whole-genome or -exome analyses have been applied for molecular and prognostic classifications as well as therapeutic implications. Mutations leading to activation of the Wnt pathway and inactivation of p53 were most frequently identified in HCC.

CONCLUSIONS

Recent advances have significantly improved our understanding of the molecular pathogenesis of HCC and its complex genetic landscape. The emerging data will open the door towards novel and more effective targeted and personalized therapies in this devastating disease.

The roles of hepatitis B virus-encoded X protein in virus replication and the pathogenesis of chronic liver disease

INTRODUCTION

Hepatitis B virus (HBV) is a major cause of chronic liver disease (CLD) and hepatocellular carcinoma (HCC) worldwide. More than 350 million people are at risk for HCC, and with few treatment options available, therapeutic approaches to targets other than the virus polymerase will be needed. This review suggests that the HBV-encoded X protein, HBx, would be an outstanding target because it contributes to the biology and pathogenesis of HBV in three fundamental ways.

AREAS COVERED

First, HBx is a trans-activating protein that stimulates virus gene expression and replication, thereby promoting the development and persistence of the carrier state. Second, HBx partially blocks the development of immune responses that would otherwise clear the virus, and protects infected hepatocytes from immune-mediated destruction. Thus, HBx contributes to the development of CLD without virus clearance. Third, HBx alters patterns of host gene expression that make possible the emergence of HCC. The selected literature cited is from the National Library of Medicine (Pubmed and Medline).

EXPERT OPINION

Understanding the mechanisms, whereby HBx supports virus replication and promotes pathogenesis, suggests that HBx will be an important therapeutic target against both virus replication and CLD aimed at the chemoprevention of HCC.

The potential of 1018 ISS adjuvant in hepatitis B vaccines: HEPLISAV™ review

Hepatitis B (HBV) virus infects the liver, and upon chronic infection, can cause liver cirrhosis and hepatocellular carcinoma. Despite universal vaccination programs against the virus, HBV still affects over 2 billion people worldwide, with over 240 million developing a chronic infection. While current alum-adjuvanted vaccines have shown efficacy in promoting seroprotection in healthy adults, 5-10% of immune-competent populations fail to achieve long-lasting seroprotection from these formulations. Furthermore, a large proportion of immunocompromised patients fail to achieve seroprotective antibody titers after receiving these vaccines. A novel vaccine candidate, HEPLISAV™, uses immunostimulatory sequences (ISS), in its formulation that helps induce a robust humoral and cell mediated immunity against HBV. In Phase III clinical trials, HEPLISAV™ has been shown to elicit seroprotective antibody titers with fewer immunizations. Similar safety profiles are demonstrated when compared with current HBV vaccines. For these reasons, HEPLISAV™ is an attractive vaccine to combat this global disease.

The hepatitis B x antigen anti-apoptotic effector URG7 is localized to the endoplasmic reticulum membrane

Hepatitis B x antigen up-regulates the liver expression of URG7 that contributes to sustain chronic virus infection and to increase the risk for hepatocellular carcinoma by its anti-apoptotic activity. We have investigated the subcellular localization of URG7 expressed in HepG2 cells and determined its membrane topology by glycosylation mapping in vitro. The results demonstrate that URG7 is N-glycosylated and located to the endoplasmic reticulum membrane with an Nlumen-Ccytosol orientation. The results imply that the anti-apoptotic effect of URG7 could arise from the C-terminal cytosolic tail binding a pro-apoptotic signaling factor and retaining it to the endoplasmic reticulum membrane.

Efficacy of early treatment on 52 patients with preneoplastic hepatitis B virus-associated hepatocellular carcinoma by compound Phyllanthus Urinaria L

OBJECTIVE

To observe the change in the number of antibodies of preneoplastic hepatocellular carcinoma (HCC) using early treatment by Compound Phyllanthus Urinaria L. (CPUL) on patients with preneoplastic hepatitis B virus (HBV)-associated HCC.

METHODS

A total of 102 cirrhosis patients with regenerative or dysplastic nodules whose sera were tested positive for at least one of these six proteins (five up-regulated genes URG4, URG7, URG11, URG12 and URG19, and one down-regulated gene DRG2) were assigned randomly to two groups using continual random codes by SPSS software. Fifty-two patients were in the treatment group and 50 patients were in the control group. CPUL was used in the treatment group for 3 years, while the control group did not receive any treatment. The changes in HBV-DNA level, number of antibodies, and hepatocarcinogenesis occurred were observed. Patients who did not develop HCC were followed up for another 2 years.

RESULTS

HBV-DNA levels decreased ⩾2log in 22.2% (10/45) of patients in the treatment group in contrast to only 5.0% (2/40) of patients in the control group (P=0.0228). The number of antibodies that were tested positive in the treatment group (1.08±1.01) was significantly lower compared with the control group (2.11±1.12) after 24 months of drug treatment (P<0.01). Both the positive rates of anti-URG11 (33/52) and anti-URG19 (31/52) were over 60% at baseline in the two groups, and were decreased to 48.1% (25/52) and 46.2% (24/52) respectively at 36 months of drug treatment, while the rates increased to 68.0% (34/50) and 66.0% (33/50) respectively (P=0.0417, P=0.0436) in the control group. The positive rate of anti-DRG2 was increased to 55.8% (29/52) at 36 months of drug treatment, while in the control group was decreased to 36.0% (18/50, P=0.0452). Among the 102 patients who developed HCC, 2 were in the treatment group and 9 were in the control group, meaning that a significant difference between the two groups (P=0.0212). In 11 patients who developed HCC, anti-URG11 and anti-URG19 were always positive, while anti-DRG2 was negative. Patients newly developing HCC were 6 (20.0%) in the control group, and only one (2.5%) in the treatment group (P=0.0441) during 2-year follow-up after the end of the treatment.

CONCLUSIONS

Anti-URG11, anti-URG19 and anti-DRG2 could be used as early markers in the prediction of the therapeutic efficacy of CPUL in treating preneoplastic HCC. CPUL is useful in preventing or delaying the development of HBV-associated cirrhosis to HCC.

Pathogenic mechanisms in HBV- and HCV-associated hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly lethal cancer, with increasing worldwide incidence, that is mainly associated with chronic hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infections. There are few effective treatments partly because the cell- and molecular-based mechanisms that contribute to the pathogenesis of this tumour type are poorly understood. This Review outlines pathogenic mechanisms that seem to be common to both viruses and which suggest innovative approaches to the prevention and treatment of HCC.

Upregulator of cell proliferation predicts poor prognosis in hepatocellular carcinoma and contributes to hepatocarcinogenesis by downregulating FOXO3a

Objective

The goal of the present study was to investigate the potential correlation between the expression level of upregulator of cell proliferation (URGCP/URG4) and the prognosis of hepatocellular carcinoma (HCC), and to examine the biological function of URGCP/URG4 in the progression of HCC, to better understand its underlying molecular mechanism in hepatic tumorigenesis.

Design

URGCP/URG4 expression was analyzed in 15 HCC cell lines, in 278 archived paraffin-embedded HCC sections, and in 10 pairs of fresh HCC tumor and para-tumor non-cancerous tissues using immunohistochemistry (IHC) and Western blotting analysis (WB). The effect of URGCP/URG4 on cell proliferation and tumorigenesis was examined in vitro and in vivo. WB and luciferase reporter analyses were performed to identify the effects of URGCP/URG4-overexpression or -knockdown on expression of cell cycle regulators and transcriptional activity of FOXO3a.

Results

IHC results revealed an upregulation of URGCP/URG4 in all HCC cell lines and fresh HCC samples as compared with normal liver cells and para-tumor tissues, respectively. URGCP/URG4 was also expressed at a high level in 122 of the 278 (43.8%) archived HCC specimens. The expression level of URGCP/URG4 was significantly correlated with clinical staging and poor patient survival of HCC in the study cohort, and in various clinical subgroups. Strikingly, ectopic expression of URGCP/URG4 induced proliferation and anchorage-independent growth of HCC cells, while silencing of URGCP/URG4 had the opposite effect. Furthermore, URGCP/URG4 overexpression in HCC cells increased cellular entry into the G1/S transitional phase, associated with downregulation of p27^Kip1 and p21^Cip1 and upregulation of cyclin D1. These effects were accompanied by enhanced Akt activity and reduced FOXO3a transcriptional activity.

Conclusions

URGCP/URG4 plays an important role in promoting proliferation and tumorigenesis of HCC and may represent a novel prognostic biomarker and therapeutic target for this disease.

Role of nuclear factor kappaB in liver health and disease

NF-kappaB (nuclear factor kappaB) is a heterodimeric transcription factor that is constitutively expressed in all cell types and has a central role as a transcriptional regulator in response to cellular stress. In the present review, we discuss the role of NF-kappaB signalling in the maintenance of liver homoeostasis as well as in the pathogenesis of a wide variety of conditions affecting the liver, including viral hepatitis, steatohepatitis, cirrhosis and hepatocellular carcinoma. Much of the current knowledge of NF-kappaB signalling in the liver relates to the canonical pathway, the IKK [IkappaB (inhibitor of kappaB) kinase] complex and the RelA subunit. We explore the weaknesses of the experimental approaches to date and suggest that further work is needed to investigate in detail the discreet functions of each of the Rel subunits in liver physiology and disease.

Mitochondria-associated HBV x antigen: what is going on?

Evaluation of: Clippinger AJ, Bouchard MJ: Hepatitis B virus HBx protein localizes to mitochondria in primary rat hepatocytes and modulates mitochrondrial membrane potential. J. Virol. 82(14), 6798–6811 (2008). Over 350 million people are chronically infected with HBV, and a significant number of these individuals develop primary liver cancer. HBV encodes seven viral proteins, including the nonstructural Hepatitis B x (HBx) protein. The results of studies with immortalized or transformed cells and with HBx transgenic mice demonstrated that HBx can interact with mitochondria. However, no studies with normal hepatocytes have characterized the precise mitochondrial localization of HBx or the effect of HBx on mitochondrial physiology. We have used cultured primary rat hepatocytes as a model system to characterize the mitochondrial localization of HBx and the effect of HBx expression on mitochondrial physiology. We now show that a fraction of HBx co-localizes with density gradient-purified mitochondria and associates with the outer mitochondrial membrane. We also demonstrate that HBx regulates mitochondrial membrane potential in hepatocytes, and that this function of HBx varies depending upon the status of NF-κB activity. In primary rat hepatocytes, HBx activation of NF-κB prevented mitochondrial membrane depolarization; however, when NF-κB activity was inhibited, HBx induced membrane depolarization through modulation of the mitochondrial permeability transition pore. Collectively, these results define potential pathways through which HBx may act in order to modulate mitochondrial physiology, thereby altering many cellular activities and ultimately contributing to the development of HBV-associated liver cancer.

Putative roles of hepatitis B x antigen in the pathogenesis of chronic liver disease

Under most circumstances, hepatitis B virus (HBV) is noncytopathic. However, hepatocellular regeneration that accompanies each bout of hepatitis appears to be associated with increased integration of HBV DNA fragments expressing the virus encoded hepatitis B x antigen (HBxAg). Intrahepatic HBxAg staining correlates with the intensity and progression of chronic liver disease (CLD), and additional work has shown that HBxAg blocks immune mediated killing by Fas and by tumor necrosis factor alpha (TNFalpha). This is not only associated with the blockage of caspase activities by HBxAg, but also by the constitutive stimulation of hepatoprotective pathways, such as nuclear factor kappa B (NF-kappaB), phosphoinositol 3-kinase (PI3K), and beta-catenin (beta-catenin). HBxAg also appears to promote fibrogenesis, by stimulating the production of fibronectin. HBxAg also stimulates the production and activity of transforming growth factor beta1 (TGFbeta1) by several mechanisms, thereby promoting the profibrogenic and tumorigenic properties of this important cytokine. In addition, HBxAg appears to remodel the extracellular matrix (ECM) by altering the expression of several matrix metalloproteinases (MMPs), which may promote tumor metastasis. Hence, HBxAg appears to promote chronic infection by preventing immune mediated apoptosis of infected hepatocytes, by promoting the establishment and persistence of fibrosis and cirrhosis preceding the development of HCC, and by promoting the remodeling of EMC during tumor progression.

HBV X protein: elucidating a role in oncogenesis

Chronic HBV infection is associated with the development of hepatocellular carcinoma (HCC). HBV contributes to tumorigenesis by encoding hepatitis B x antigen (HBxAg), which is a trans-regulatory protein that appears to contribute to HCC by altering patterns of host gene expression. In this review, recent data is presented that outlines some of the putative mechanisms whereby HBxAg contributes to HCC. With the development of animal models of HBxAg-mediated HCC, the relevance and temporal order of putative steps in this process can now be dissected to elucidate what is rate limiting and when. This will have a profound impact on the design of novel and specific therapeutics for HCC.