Mechanisms of HBV-related hepatocarcinogenesis

Genetic Landscape and Biomarkers of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) has emerged as a major cause of cancer-related death. Its mortality has increased in Western populations, with a minority of patients diagnosed at early stages, when curative treatments are feasible. Only the multikinase inhibitor sorafenib is available for the management of advanced cases. During the last 10 years, there has been a clear delineation of the landscape of genetic alterations in HCC, including high-level DNA amplifications in chromosome 6p21 (VEGFA) and 11q13 (FGF19/CNND1), as well as homozygous deletions in chromosome 9 (CDKN2A). The most frequent mutations affect TERT promoter (60%), associated with an increased telomerase expression. TERT promoter can also be affected by copy number variations and hepatitis B DNA insertions, and it can be found mutated in preneoplastic lesions. TP53 and CTNNB1 are the next most prevalent mutations, affecting 25%-30% of HCC patients, that, in addition to low-frequency mutated genes (eg, AXIN1, ARID2, ARID1A, TSC1/TSC2, RPS6KA3, KEAP1, MLL2), help define some of the core deregulated pathways in HCC. Conceptually, some of these changes behave as prototypic oncogenic addiction loops, being ideal biomarkers for specific therapeutic approaches. Data from genomic profiling enabled a proposal of HCC in 2 major molecular clusters (proliferation and nonproliferation), with differential enrichment in prognostic signatures, pathway activation and tumor phenotype. Translation of these discoveries into specific therapeutic decisions is an unmet medical need in this field.

Hepatitis B virus X protein induces the histone H3 lysine 9 trimethylation on the promoter of p16 gene in hepatocarcinogenesis

Our previous study showed hepatitis B virus X protein (HBx) suppresses the p16 expression in hepatocarcinogenesis. In this study we explored the relationship between HBx and trimethylation of H3K9 (H3K9me3), and elucidated the underlying mechanisms in HBx inducing the tumor suppressor p16 gene silence. SMMC-7721 and HepG2 hepatoma cell lines were transfected with HBx-expressing plasmid. Immunohistochemistry, Western blotting and real-time polymerase chain reaction, were performed to detect the expressions of HBx, H3K9me3, and jumonji domain-containing protein 2B (JMJd2B). H3K9me3 enrichment on the p16 promoter was measured by immunoprecipitation-PCR (ChIP-PCR) analyses, and 39 cases of hepatitis B virus (HBV) associated-hepatocellular carcinoma (HCC) and corresponding noncancerous liver tissues were also examined. We demonstrated that HBx was able to upregulate H3K9me3 and suppress JMJd2B mRNA and protein levels in SMMC-7721 and HepG2 hepatoma cell lines. JMJd2B, as a specific target of H3K9me3 for demethylation, was inversely correlated with the levels of H3K9me3 in SMMC-7721 (r=-0.666, P<0.05) and HepG2 cells (r=-0.625, P<0.05). The ChIP-PCR data indicated that HBx remarkably increased H3K9me3 on the p16 promoter region. Immunohistochemistry analysis showed that H3K9me3 expression in HBx positive HCC samples were significantly higher than that in HBx negative HCC tissues and were associated with decreased levels of JMJd2B expression. JMJd2B immunoreactivity was also remarkably inversed to that of HBx in HCC tissues (r=-0.630, P<0.05). Our results provide evidence that HBx is able to induce H3K9me3 on the p16 promoter via the decrease of demethylase JMJd2B expression and thus promote the repression of p16 gene expression to enhance hepatocarcinogenesis.

Recurrent AAV2-related insertional mutagenesis in human hepatocellular carcinomas

Hepatocellular carcinomas (HCCs) are liver tumors related to various etiologies, including alcohol intake and infection with hepatitis B (HBV) or C (HCV) virus. Additional risk factors remain to be identified, particularly in patients who develop HCC without cirrhosis. We found clonal integration of adeno-associated virus type 2 (AAV2) in 11 of 193 HCCs. These AAV2 integrations occurred in known cancer driver genes, namely CCNA2 (cyclin A2; four cases), TERT (telomerase reverse transcriptase; one case), CCNE1 (cyclin E1; three cases), TNFSF10 (tumor necrosis factor superfamily member 10; two cases) and KMT2B (lysine-specific methyltransferase 2B; one case), leading to overexpression of the target genes. Tumors with viral integration mainly developed in non-cirrhotic liver (9 of 11 cases) and without known risk factors (6 of 11 cases), suggesting a pathogenic role for AAV2 in these patients. In conclusion, AAV2 is a DNA virus associated with oncogenic insertional mutagenesis in human HCC.

Lack of infectivity of HBV in feces from patients with chronic hepatitis B virus infection, and infection using chimeric mice

BACKGROUND

Body fluids such as saliva and tears from patients with hepatitis B virus (HBV) infection are known as infectious agents. The infectivity of feces from patients with HBV infection has not been established. The aim of this study was to determine whether feces from HBV carriers can be a source of HBV infection.

METHODS

Thirty-three children and 17 adults (ages 0-49 years, median age 13 years) who were chronically infected with HBV were enrolled. The levels of HBV DNA in the feces from these patients were quantified by real-time PCR, and the levels of fecal HBsAg were measured. Isolated human hepatocytes from chimeric mice with humanized livers were co-cultured with serum, tears and feces from the HBV carriers. Four chimeric mice were inoculated intravenously with sterilized feces from HBV carriers.

RESULTS

HBV DNA was detected in the feces of 37 (74%) of the 50 patients. The fecal HBV DNA levels ranged from 2.8 to 8.4 log copies/mL (mean ± SD  =  5.6 ± 1.2 log copies/mL). A significant correlation was observed in the levels of HBV DNA between serum and feces (r  =  0.54, p < 0.05). Of the 13 HBV carries, 7 (54%) were positive for fecal HBsAg. The fecal HBsAg levels ranged from 0.06 to 1.0 IU/mL (median 0.28 IU/mL). Immunogold electron microscopy showed Dane particles in feces. HBV DNA was detected in the human hepatocytes co-cultured with serum and tears, but not in those co-cultured with feces. HBV DNA was not detected in the serum of the chimeric mice after oral or intravenous inoculation with sterilized fecal samples, which contained 5 log copies/mL of HBV DNA levels.

CONCLUSIONS

Although the positive rate of fecal HBV DNA was high, the fecal HBsAg levels were extremely low. The chimeric mice were not infected with HBV after oral or intravenous inoculation with sterilized fecal samples. Therefore, feces from HBV carriers seem not to serve as an infectious vehicle for the transmission of HBV.

Role of alpha-fetoprotein in hepatitis B virus-induced hepatocellular carcinoma: Prospect in clinical application

Mammalian alpha-fetoprotein (AFP) as a fetal specific alpha-globulin that has been used as a serum fetal defect/tumor marker for diagnosis and prediction of liver disease. Over the past decade, research indicates that AFP as an intracellular signal molecule is not only a biomarker but also interacts with hepatitis B virus (HBV) and hepatitis B virus protein x and plays multifarious roles in the development of hepatocellular carcinoma, especially in HBV-induced liver cancer.

Toll-like receptor 4 regulates hepatitis B virus related hepatic carcinoma cell proliferation by controlling cyclin-dependent kinase 4/6 expression

AIM: To explore the effect of Toll-like receptor 4 (TLR4) on the proliferation of hepatitis B virus (HBV) related hepatic carcinoma cells and the underlying mechanism.

METHODS: The expression of TLR4, cyclin-dependent kinase (CDK) 4 and CDK6 protein in 36 HBV-related hepatic carcinoma tissues and matched adjacent tissues were detected by Western blot, and their correlations in carcinoma tissues were analyzed. Three TLR4 specific siRNAs and a negative control were synthesized and transfected into hepatoma cells Hep-3B using liposomes. The siRNA sequence with the best performance was selected for Western blot analysis. The expression of TLR4, CDK4 and CDK6 proteins was measured by Western blot assay before and after transfection. The proliferation of hepatoma cells was observed by MTT assay and colony formation assay.

RESULTS: The overall expression levels of TLR4, CDK4 and CDK6 proteins in HBV-related hepatic carcinoma were significantly higher than those in the matched adjacent tissues (P < 0.05). There was a positive correlation between TLR4 and CDK4 expression (r = 0.66, P < 0.05), and between TLR4 and CDK6 expression (r = 0.57, P < 0.05). Using the best interference sequence (TLR4-siRNA-03), it was found that the protein levels of CDK4 and CDK6 were significantly decreased in the TLR4-siRNA group (P < 0.05), compared to the control group. In addition, the proliferation of Hep-3B cells and the colony formation rate were both decreased (P < 0.05) in the TLR4-siRNA group.

CONCLUSION: TLR4 may regulate the proliferation of HBV-related hepatic carcinoma cells by controlling the expression of CDK4 and CDK6.

MicroRNAs as Important Players in Host-hepatitis B Virus Interactions

Hepatitis B virus (HBV) infection, a major public health problem, causes acute and chronic hepatitis that is often complicated by liver cirrhosis and hepatocellular carcinoma. The pathogenic mechanisms of HBV-related liver disease are not well understood, and the current licensed therapies are not effective in permanently clearing virus from the circulation. In recent years, the role of micro-ribonucleic acids (miRNAs) in HBV infection has attracted great interest. Cellular miRNAs can influence HBV replication directly by binding to HBV transcripts and indirectly by targeting cellular factors relevant to the HBV life cycle. They are also involved in the regulation of cellular genes and signaling pathways that have critical roles in HBV pathogenesis. HBV infection, in turn, can trigger changes in cellular miRNA expression that are associated with distinctive miRNA expression profiles depending on the phase of liver disease. These alterations in miRNA expression have been linked to disease progression and hepatocarcinogenesis. We provide here an up to date review regarding the field of miRNAs and HBV interplay and highlight the potential utility of miRNAs as diagnostic biomarkers and therapeutic targets for the management of HBV-related liver disease.

Th1/Th2 cytokines and their genotypes as predictors of hepatitis B virus related hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the predominant type of primary liver cancer, is one of the most serious life-threatening malignancies, worldwide. In majority of the cases, HCC develops after prolonged and persistent chronic liver disease. hepatitis B virus (HBV) or HCV infection is prominent etiological factors, attributing to this condition. It has been well documented that HBV, being the inducer of chronic inflammation, is the main causative agent in causing HCC, particularly in Asian countries. The HBV infection leads to a wide range of clinical symptoms from carrier state to malignancy. Cytokines being immune-modulatory molecules, are the key mediators in the defense mechanism against viral infection. In this regard, this review will detail the substantial role of key Th1: interleukin 1 (IL-1), IL-2, IL-12, tumor necrosis factor-α, interferon-γ; Th2: IL-4, IL-10 and non Th1/Th2: IL-6, transforming growth factor-β1 cytokines genotypes in analyzing the variability in the clinical manifestations in an HBV-afflicted individual, which might finally, culminates into HCC. Since cytokine production is regulated genetically, the cytokine promoter region single-nucleotide polymorphisms induced changes, greatly affects the cytokine production, thus resulting into differential outcome of immune balance.

Key role of hepatitis B virus mutation in chronic hepatitis B development to hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC). The HBV mutations, which include point mutation, deletion, insertion and truncation mutation of HBV gene in 4 open reading frames (S, C, P, X), are closely associated with HCC pathogenesis. Some mutations accumulated during chronic HBV infection could be regarded as a biomarker to predict the occurrence of HCC. The detection of the mutations in clinical practice could be helpful for defining better preventive and therapeutic strategies and, moreover, predicting the progression of liver disease.

Risk for hepatocellular carcinoma in the course of chronic hepatitis B virus infection and the protective effect of therapy with nucleos(t)ide analogues

Hepatocellular carcinoma (HCC) is a major health problem worldwide, representing one of the leading causes of death. Chronic hepatitis B virus (HBV) infection (CHB) is the most important etiologic factor of this tumor, accounting for the development of more than 50% of the cases in the world. Primary prevention of HCC is possible by hepatitis B vaccination conferring protection from HBV infection. However, according to the World Health Organization Hepatitis B Fact sheet N° 204 (update of July 2014) globally there exists a large pool of > 240 million people chronically infected with HBV who are at risk for development of HCC. These individuals represent a target population for secondary prevention both of cirrhosis and of HCC. Since ongoing HBV replication in CHB is linked with the progression of the underlying liver disease to cirrhosis as well as with the development of HCC, effective antiviral treatment in CHB has also been evaluated in terms of secondary prevention of HCC. Currently, most patients with active CHB are subjected to long term treatment with the first line nucleos(t)ide analogues entecavir and tenofovir. These compounds are of high antiviral potency and have a high barrier to HBV resistance compared to lamivudine, adefovir dipivoxil and even telbivudine. Many studies have shown that patients under antiviral treatment, especially those in virological remission, develop less frequently HCC compared to the untreated ones. However, the risk for development of HCC cannot be eliminated. Therefore, surveillance for the development of HCC of patients with chronic hepatitis B must be lifelong or until a time in the future when new treatments will be able to completely eradicate HBV from the liver particularly in the early stages of CHB infection. In this context, the aim of this review is to outline the magnitude of the risk for development of HCC among patients with CHB, in the various phases of the infection and in relation to virus, host and environmental factors as evaluated in the world literature. Moreover, the benefits of antiviral treatment of CHB with nucleos/tide analogs, which have changed the natural history of the disease and have reduced but not eliminated the risk of HCC are also reviewed.

Covalently closed-circular hepatitis B virus DNA reduction with entecavir or lamivudine

AIM: To investigate the reduction in hepatitis B virus (HBV) covalently closed-circular DNA (cccDNA) with entecavir (ETV) or lamivudine (LAM).

METHODS: This analysis included patients who had participated in the randomized Phase III study ETV-022 comparing ETV vs LAM in nucleos(t)ide-naive, HBeAg-positive patients. Patients received ETV (0.5 mg daily) or LAM (100 mg daily) for a minimum of 52 wk. Patients were eligible to participate in this sub-study if they had paired biopsies at baseline and week 48 with evaluable measurements for hepatic HBV cccDNA and total hepatic HBV DNA. The main objective was to compare changes in hepatic HBV cccDNA and total hepatic HBV DNA at week 48 of ETV or LAM treatment, which was a secondary endpoint of study ETV-022. Additional post hoc analyses included linear regression analyses to assess associations of baseline levels and on-treatment changes of cccDNA with other baseline factors [sex, age, serum HBV DNA, alanine aminotransferase (ALT), Knodell necroinflammatory score, Ishak fibrosis score, total hepatic HBV DNA, and HBV genotype], or on-treatment factors (changes from baseline at week 48 in serum HBV DNA, ALT, Knodell necroinflammatory score, Ishak fibrosis score, total hepatic HBV DNA, and HBeAg loss at week 48).

RESULTS: Overall, 305 patients (ETV = 159; LAM = 146) of ETV-022 had paired baseline and week 48 liver biopsies with evaluable measurements for hepatic HBV cccDNA and total hepatic HBV DNA, and were included in this analysis. Baseline demographics and disease characteristics were comparable between the two arms. After 48 wk, ETV resulted in significantly greater reductions in hepatic HBV cccDNA [-0.9 log₁₀ copies/human genome equivalent (HGEq) vs -0.7 log₁₀ copies/HGEq; P = 0.0033] and total hepatic DNA levels (-2.1 log₁₀ copies/HGEq vs -1.6 log₁₀ copies/HGEq; P < 0.0001) than LAM. Virologic, biochemical, and histologic response rates at week 48 were also greater with ETV than with LAM. Baseline HBV cccDNA levels were positively associated with baseline levels of serum HBV DNA and total hepatic HBV DNA, and negatively associated with HBV genotype F. On-treatment changes in HBV cccDNA levels were negatively associated with baseline levels of serum HBV DNA and baseline ALT, and were positively associated with on-treatment changes in the levels of serum HBV DNA, total hepatic HBV DNA levels, and ALT, change in Knodell necroinflammatory score, and HBeAg loss.

CONCLUSION: Forty-eight weeks of ETV resulted in greater reductions in cccDNA and total hepatic HBV DNA than LAM, but long-term therapy may be needed for cccDNA elimination.

HBx co-localizes with COXIII in HL-7702 cells to upregulate mitochondrial function and ROS generation

Hepatocellular carcinoma (HCC) is one of the most common malignant diseases, and HBx leads to the development of HBV-associated HCC. Mitochondria are key organelles that regulate apoptosis, cellular energetics and signal transduction pathways, and are the source of HBx-induced reactive oxygen species (ROS). Recent findings have shown that HBx interacts with the inner mitochondrial membrane protein, COXIII, via the yeast two-hybrid system, mating experiment and coimmunoprecipitation. The aim of the present study was to examine the co-localizaiton of HBx and COXIII in HL-7702 cells and to investigate ensuing alterations of mitochondrial function. An HL-7702 cell line stably expressing the HBx gene by lentivirus vectors was constructed. Confocal microscopy was utilized to assess the interaction between HBx protein and COXIII. Expression of COXIII, activities of cytochrome c oxidase (COX) and the mitochondrial membrane potential, which were functionally relevant to the HBx protein-COXIII interaction, were investigated in cell cultures. Moreover, the intracellular ROS levels were detected by flow cytometry. The results demonstrated that HBx co-localized with the inner mitochondrial protein, COXIII, in HL-7702 cells, causing the upregulation of COXIII protein expression as well as COX activity. However, HBx did not alter the mitochondrial membrane potential and mitochondria exhibited only slight swelling in HL-7702-HBx cells. Moreover, HBx elevated the generation of mitochondrial ROS in HL-7702-HBx cells. The main finding of the present study was that the co-localization of HBx and COXIII leads to upregulation of the mitochondrial function and ROS generation, which are associated with the oncogenesis of HBV-associated HCC.

MicroRNA responses to environmental liver carcinogens: Biological and clinical significance

A large number of biological, chemical, and dietary factors have been implicated in the development of liver cancer. These involve complex and protracted interactions between genetic, epigenetic, and environmental factors. The survival rate for patients diagnosed with late-stage liver cancer is currently low due to the aggressive nature of the disease and resistance to therapy. An increasing body of evidence has offered support for the crucial role of non-coding microRNA (miRNA) in directing hepatic responses to environmental risk factors for liver cancer. In this review we focus on miRNA responses to environmental liver cancer risk factors and their potential biological and clinical significance.

Serum Golgi protein 73 (GP73) is a diagnostic and prognostic marker of chronic HBV liver disease

Alanine aminotransferase (ALT) is the most commonly used marker of liver injury, but normal ALT levels are seen in a proportion of chronic hepatitis B virus (HBV)-infected patients with severe liver injury. Golgi protein 73 (GP73) is a promising alternative marker of liver injury. This study assessed the relation between GP73 levels and liver disease severity, monitored the kinetic changes in GP73 levels in chronic HBV patients receiving entecavir (ETV) therapy, and investigated the potential diagnostic and prognostic values of serum GP73 as a new liver injury biomarker in chronic HBV infections. This study enrolled 1150 patients with chronic HBV infections, 200 of whom were retrospectively enrolled in this study after receiving 1 year of ETV treatment. GP73 expression in liver tissue was detected by immunohistochemistry. GP73 levels in single or serial serum samples were measured by enzyme-linked immunosorbent assay. Immunohistochemical analysis indicated that GP73 protein expression in the liver increased progressively with pathologic progression from nonexistent or mild hepatitis to severe hepatitis and cirrhosis during chronic HBV infection. Serum GP73 levels were positively correlated with the disease severity of chronic HBV infections (r = 0.58, P < 0.001). In patients with normal ALT levels, serum GP73 concentrations were significantly higher in patients with prominent hepatic inflammatory injury and fibrosis than in patients without hepatic inflammatory injury or fibrosis. Serum GP73 concentrations and GP73 protein expression were decreased in the liver tissues of patients whose ALT levels normalized after 1 year of ETV antiviral therapy. Changes in serum GP73 levels were closely associated with changes in liver injury severity, and, therefore, GP73 may be an effective new liver inflammatory injury biomarker, and could be useful for monitoring the prognosis of chronic HBV infectious patients with normal ALT levels.

Turning hepatic cancer stem cells inside out--a deeper understanding through multiple perspectives

Hepatocellular carcinoma (HCC), a highly malignant disease and the third leading cause of all cancer mortalities worldwide, often responses poorly to current treatments and results in dismal outcomes due to frequent chemoresistance and tumor relapse. The heterogeneity of HCC is an important attribute of the disease. It is the outcome of many factors, including the cross-talk between tumor cells within the tumor microenvironment and the acquisition and accumulation of genetic and epigenetic alterations in tumor cells. In addition, there is accumulating evidence in recent years to show that the malignancy of HCC can be attributed partly to the presence of cancer stem cell (CSC). CSCs are capable to self-renew, differentiate and initiate tumor formation. The regulation of the stem cell-like properties by several important signaling pathways have been found to endow the tumor cells with an increased level of tumorigenicity, chemoresistance, and metastatic ability. In this review, we will discuss the recent findings on hepatic CSCs, with special emphasis on their putative origins, relationship with hepatitis viruses, regulatory signaling networks, tumor microenvironment, and how these factors control the stemness of hepatic CSCs. We will also discuss some novel therapeutic strategies targeted at hepatic CSCs for combating HCC and perspectives of future investigation.

3D hotspots of recurrent retroviral insertions reveal long-range interactions with cancer genes

Genomically distal mutations can contribute to the deregulation of cancer genes by engaging in chromatin interactions. To study this, we overlay viral cancer-causing insertions obtained in a murine retroviral insertional mutagenesis screen with genome-wide chromatin conformation capture data. Here we find that insertions tend to cluster in 3D hotspots within the nucleus. The identified hotspots are significantly enriched for known cancer genes, and bear the expected characteristics of bona fide regulatory interactions, such as enrichment for transcription factor-binding sites. In addition, we observe a striking pattern of mutual exclusive integration. This is an indication that insertions in these loci target the same gene, either in their linear genomic vicinity or in their 3D spatial vicinity. Our findings shed new light on the repertoire of targets obtained from insertional mutagenesis screening and underline the importance of considering the genome as a 3D structure when studying effects of genomic perturbations.

The direct and indirect roles of HBV in liver cancer: prospective markers for HCC screening and potential therapeutic targets

Chronic hepatitis B virus (HBV) infection remains the number one risk factor for hepatocellular carcinoma (HCC), accounting for more than 600 000 deaths/year. Despite highly effective antiviral treatment options, chronic hepatitis B (CHB), subsequent end-stage liver disease and HCC development remain a major challenge worldwide. In CHB, liver damage is mainly caused by the influx of immune cells and destruction of infected hepatocytes, causing necro-inflammation. Treatment with nucleoside/nucleotide analogues can effectively suppress HBV replication in patients with CHB and thus decrease the risk for HCC development. Nevertheless, the risk of HCC in treated patients showing sufficient suppression of HBV DNA replication is significantly higher than in patients with inactive CHB, regardless of the presence of baseline liver cirrhosis, suggesting direct, long-lasting, predisposing effects of HBV. Direct oncogenic effects of HBV include integration in the host genome, leading to deletions, cis/trans-activation, translocations, the production of fusion transcripts and generalized genomic instability, as well as pleiotropic effects of viral transcripts (HBsAg and HBx). Analysis of these viral factors in active surveillance may allow early identification of high-risk patients, and their integration into a molecular classification of HCC subtypes might help in the development of novel therapeutic approaches.

Male-specific hepatitis B virus large surface protein variant W4P potentiates tumorigenicity and induces gender disparity

BACKGROUND

The underlying mechanisms of carcinogenesis and gender disparity in hepatitis B virus (HBV)-induced hepatocellular carcinoma (HCC) remain unclear. Recently, we reported a novel HCC-related W4P/R mutation in the large surface protein (LHB) of HBV genotype C, which was found exclusively in male HCC patients.

METHODS

LHB sequences from a carrier (wild type; WT) and W4P variant LHB sequence from an HCC patient were cloned and used to generate NIH3T3 and Huh7 cell lines. Cell proliferation and in vitro tumorigenicity were assessed by cell growth and transformation assays. Male and female nude mice were injected with the cells to determine in vivo tumorigenicity. To confirm the effect of estrogen in W4P-mediated tumorigenicity, male mice were injected with estrogen and challenged with W4P-expressing cells. The serum levels of different cytokines from the mouse model and patients were analyzed by ELISA. A critical role of interleukin (IL)-6 signaling in W4P-mediated tumorigenicity was tested by inhibition of Jak2.

RESULTS

Although both WT and W4P variant LHBs enhanced cell proliferation by regulating the cell cycle and facilitated cell colony formation, the W4P variant demonstrated significantly higher activity. NIH3T3 cells expressing variant LHB, but not the WT, induced tumor in a nude mouse model. Tumor masses produced by variant LHB were significantly larger in male than female mice, and significantly reduced by estrogen. IL-6, but not tumor necrosis factor-α, was elevated in male mice harboring W4P-induced tumor, and was reduced by estrogen. IL-6 levels of HCC patients with the W4P variant were significantly higher than those of patients with WT LHB. W4P LHB induced higher production of IL-6 than WT LHB in cell lines, and the level was reduced by estrogen. The ability to reduce cell proliferation and colony formation of W4P LHB was hampered by inhibition of IL-6 signaling.

CONCLUSIONS

This study suggests that the W4P mutation during the natural course of chronic hepatitis B infection may contribute to HCC development, particularly in male patients, in an IL-6-dependent manner.

Hepatocellular carcinoma

The hepatitis B virus (HBV) is a widespread human pathogen that causes liver inflammation, cirrhosis, and hepatocellular carcinoma (HCC). Recent sequencing technologies have refined our knowledge of the genomic landscape and pathogenesis of HCC, but the mechanisms by which HBV exerts its oncogenic role remain controversial. In a prevailing view, inflammation, liver damage, and regeneration may foster the accumulation of genetic and epigenetic defects leading to cancer onset. However, a more direct and specific contribution of the virus is supported by clinical and biological observations. Among genetically heterogeneous HCCs, HBV-related tumors display high genomic instability, which may be attributed to the ability of HBV to integrate its DNA into the host cell genome, provoking chromosomal alterations and insertional mutagenesis of cancer genes. The viral transactivator HBx may also participate in transformation by deregulating diverse cellular machineries. A better understanding of the complex mechanisms linking HBV to HCC will improve prevention and treatment strategies.

Next generation digital PCR measurement of hepatitis B virus copy number in formalin-fixed paraffin-embedded hepatocellular carcinoma tissue

BACKGROUND

Hepatocellular carcinoma (HCC) is strongly associated with hepatitis B virus (HBV) infection. False-negative results are common in routine serological tests and quantitative real-time PCR because of HBV surface antigen (HBsAg) variation and low HBV copy number. Droplet digital PCR (ddPCR), a next generation digital PCR, is a novel, sensitive, and specific platform that can be used to improve HBV detection.

METHODS

A total of 131 HCC cases with different tumor stages and clinical features were initially classified with a serological test as HBsAg positive (n = 107) or negative (n = 24) for HBV infection. Next, DNA templates were prepared from the corresponding formalin-fixed paraffin-embedded (FFPE) tissues to determine HBV copy number by ddPCR.

RESULTS

HBV copy numbers, successfully determined for all clinical FFPE tissues (n = 131), ranged from 1.1 to 175.5 copies/μL according to ddPCR. The copy numbers of HBV were positively correlated with tumor-nodes-metastasis (P = 0.008) and Barcelona-Clinic Liver Cancer (P = 0.045) classification. Moreover, serum cholinesterase correlated with hepatitis B viral load (P = 0.006).

CONCLUSIONS

HBV infection is a key factor that influences tumorigenesis in HCC by regulating tumor occurrence and development. ddPCR improves the analytical sensitivity and specificity of measurements in nucleic acids at a single-molecule level and is suitable for HBV detection.

Hepatitis B virus regulates apoptosis and tumorigenesis through the microRNA-15a-Smad7-transforming growth factor beta pathway

Hepatitis B virus (HBV) infection causes chronic hepatitis in hundreds of millions of people worldwide, which can eventually lead to hepatocellular carcinoma (HCC). Previously, we found that HBV mRNAs can absorb microRNA-15a (miR-15a) to affect apoptosis through the Bcl-2 pathway. We asked whether HBV could inhibit apoptosis and promote tumorigenesis through different pathways. In this study, we found that the transforming growth factor β (TGF-β) pathway-inhibitory factor Smad7 is a novel target of miR-15a. We demonstrated that HBV can upregulate the level of Smad7 by downregulating miR-15a. Furthermore, we examined the level of Smad7 in liver samples from HBV-infected HCC patients and found that HBV mRNAs are positively correlated with the level of Smad7. By taking the approach of using immunoblotting and luciferase reporter assays, we revealed that HBV can abrogate TGF-β signaling via upregulating Smad7. By using annexin V staining and caspase 3/7 activity assays, we found that HBV can inhibit TGF-β-induced apoptosis of HepG2 cells. We also showed that HBV can promote tumor growth in BALB/c nude mice through upregulating the expression of Smad7. In conclusion, we demonstrated that HBV can upregulate Smad7 expression and inhibit TGF-β signaling, which makes the cells resistant to TGF-β-induced apoptosis and promotes tumorigenesis.

IMPORTANCE

Hepatitis B virus (HBV) infection causes chronic hepatitis, which can eventually lead to hepatocellular carcinoma (HCC). TGF-β signaling is closely linked to liver fibrosis, cirrhosis, and subsequent HCC progression and plays a unique role in the pathogenesis of HCC. At the early stage of tumor formation, TGF-β functions as a tumor suppressor that inhibits cell proliferation and induces apoptosis. Previously, we found that HBV mRNAs can sponge off miR-15a to affect apoptosis through the Bcl-2 pathway. In this study, we identified that the TGF-β-inhibitory factor Smad7 is a novel target of miR-15a. We reveal that HBV can abrogate TGF-β signaling via upregulating Smad7, inhibit TGF-β-induced apoptosis, as well as promote tumor development. Our study provides evidence to support the idea that viral RNAs can exert their functions as competing endogenous RNAs (ceRNAs) toward microRNA and participate in important cellular processes.

Metastatic tumor antigen in hepatocellular carcinoma: golden roads toward personalized medicine

Hepatocellular carcinoma (HCC), a prototype of hypervascular tumors, is one of the most common malignancies in the world, especially hyperendemic in the Far East where chronic hepatitis B virus (HBV) infection is highly prevalent. It is characterized by the clinical feature of a poor prognosis or a high mortality due to its already far advanced stages at diagnosis. It is so multifactorial that hepatocarcinogenesis cannot be explained by a single molecular mechanism. To date, a number of pathways have been known to contribute to the development, growth, angiogenesis, and even metastasis of HCC. Among the various factors, metastatic tumor antigens (MTAs) or metastasis-associated proteins have been vigorously investigated as an intriguing target in the field of hepatocarcinogenesis. According to recent studies including ours, MTAs are not only involved in the HCC development and growth (molecular carcinogenesis), but also closely associated with the post-operative recurrence and a poor prognosis or a worse response to post-operative anti-cancer therapy (clinical significance). Herein, we review MTAs in light of their essential structure, functions, and molecular mechanism in hepatocarcinogenesis. We will also focus in detail on the interaction between hepatitis B x protein (HBx) of HBV and MTA in order to clarify the HBV-associated HCC development. Finally, we will discuss the prognostic significance and clinical application of MTA in HCC. We believe that this review will help clinicians to understand the meaning and use of the detection of MTA in order to more effectively manage their HCC patients.

Interactome map reveals phospholipid scramblase 1 as a novel regulator of hepatitis B virus x protein

HBV X protein plays crucial roles during viral infection and hepatocellular carcinoma (HCC) development through interaction with various host factors. Here, we mapped the interactome of HBx using a yeast two-hybrid screen. Nine human proteins were identified as novel interacting partners of HBx, one of which is phospholipid scramblase 1 (PLSCR1). PLSCR1 is an interferon-inducible protein that mediates antiviral activity against DNA and RNA viruses. However, the molecular mechanisms of PLSCR1 activity against HBV remain unclear. Here, we reported that PLSCR1 promotes HBx degradation by a proteasome- and ubiquitin-dependent mechanism. Furthermore, we found that PLSCR1 inhibits HBx-mediated cell proliferation. After HBV infection, the protein level of PLSCR1 in plasma is elevated, and chronic hepatitis B patients with low plasma levels of PLSCR1 have a high risk of developing HCC. These results suggest that the nuclear trafficking of PLSCR1 mediates the antiviral activity and anticarcinogenesis against HBV by regulating HBx stability.

Cell cycle-related kinase mediates viral-host signalling to promote hepatitis B virus-associated hepatocarcinogenesis

BACKGROUND

Androgen receptor (AR) signalling contributes to male predominance in hepatocellular carcinoma (HCC), which is more pronounced in HBV-endemic areas. Cell cycle-related kinase (CCRK) is essential for AR-induced hepatocarcinogenesis but its molecular function in HBV-associated HCC remains obscure.

OBJECTIVE

To determine the molecular function of CCRK in HBV-associated HCC.

DESIGN

Transcriptional regulation was assessed by chromatin immunoprecipitation, promoter mutation and luciferase reporter assays. Hepatocellular proliferation and tumourigenesis were examined by colony formation, soft agar assays and using HBV X protein (HBx) transgenic mice with low-dose exposure to diethylnitrosamine. Protein expressions were examined in clinical samples and correlated with patient survival by log-rank Mantel-Cox test.

RESULTS

Overexpression of CCRK, but not its kinase-defective mutant, activated β-catenin/T cell factor signalling through phosphorylation of glycogen synthase kinase-3β (GSK-3β) at Ser9, led to upregulation of AR transcriptional activity and, subsequently, expression of HBx. The viral transactivator in turn induced CCRK expression through enhanced AR signalling, thus forming a positive regulatory loop. RNA interference silencing of CCRK, which suppressed the CCRK/GSK-3β/β-catenin/AR regulatory loop, significantly suppressed HBx-induced hepatocellular proliferation (p=0.001) and transformation (p<0.001) and remarkably reduced >80% diethylnitrosamine-mediated hepatocarcinogenesis in HBx transgenic mice. Finally, patients with HBV-associated HCC with concordant overexpression of CCRK, GSK-3β phosphorylation at Ser9, active dephosphorylated β-catenin and AR phosphorylation at Ser81 had poorer overall (HR=31.26, p<0.0001) and disease-free (HR=3.60, p<0.01) survival rates.

CONCLUSIONS

Our findings highlight the critical role of CCRK in a self-reinforcing circuitry that regulates HBV-associated hepatocarcinogenesis. Further characterisation of this intricate viral-host signalling may provide new prognostic biomarkers and therapeutic targets for HCC treatment.

Requirement of CRTC1 coactivator for hepatitis B virus transcription

Transcription of hepatitis B virus (HBV) from the covalently closed circular DNA (cccDNA) template is essential for its replication. Suppressing the level and transcriptional activity of cccDNA might have anti-HBV effect. Although cellular transcription factors, such as CREB, which mediate HBV transcription, have been well described, transcriptional coactivators that facilitate this process are incompletely understood. In this study we showed that CREB-regulated transcriptional coactivator 1 (CRTC1) is required for HBV transcription and replication. The steady-state levels of CRTC1 protein were elevated in HBV-positive hepatoma cells and liver tissues. Ectopic expression of CRTC1 or its homolog CRTC2 or CRTC3 in hepatoma cells stimulated the activity of the preS2/S promoter of HBV, whereas overexpression of a dominant inactive form of CRTC1 inhibited HBV transcription. CRTC1 interacts with CREB and they are mutually required for the recruitment to the preS2/S promoter on cccDNA and for the activation of HBV transcription. Accumulation of pregenomic RNA (pgRNA) and cccDNA was observed when CRTC1 or its homologs were overexpressed, whereas the levels of pgRNA, cccDNA and secreted HBsAg were diminished when CRTC1 was compromised. In addition, HBV transactivator protein HBx stabilized CRTC1 and promoted its activity on HBV transcription. Our work reveals an essential role of CRTC1 coactivator in facilitating and supporting HBV transcription and replication.

Genetic insights on host and hepatitis B virus in liver diseases

Hepatitis B virus (HBV) infection is a major global health problem and many studies have underlined the importance of inter individual variability and somatic mutations during the clinical course of HBV infection. In recent years, high-throughput technologies have provided new possibilities to study the genetic basis of many diseases. We reviewed all literature available on genome-wide association studies (GWASs), whole genome, exome and RNA sequencing studies as well as studies on HBV infection and the pathogenesis of related liver disease. Many GWASs conclude that the genetic variants in the HLA region (HLA-DP, HLA-DQ, HLA-DR and MICA), KIF1B, DEPDC5 and PNPLA3 influence HBV infection, its clinical course and the response to hepatitis B vaccination. The next generation sequencing approach provides important clues on the mutational landscape of genes involved in signaling pathways in particular JAK/STAT, Wnt/β-catenin, p53 pathways and multiple chromatin regulator genes that significantly promote hepatocarcinogenesis. In addition, the hotspots of recurrent integrations of HBV-DNA into host chromosomes such as hTERT, PDGF receptor, MLL are involved in pathogenesis of hepatocellular carcinoma (HCC). Additionally, the transitions T>C/A>G, C>T/G>A, C>A/G>T and T>A/A>T remain specific for HCC induced by viral infection and the DNA methylation in the CpG island is proposed as a biomarker for HCC. We have described common mutations in the HBV genome (G1896A, rtM204V, rtM204I) which modulate the pathogenesis and carcinogenesis of the liver. Further GWASs in different ethnic groups and additional functional studies are required to warrant the significance of such defined genetic factors. Such findings continue to shape our understanding of the genetic architecture of host-virus interactions and provide new clues and directions in determining genetic markers that modulate HBV infection and related liver diseases. The studies using high-throughput technologies help identifying potential genetic threats however the utility of mutational information can be complex in predicting prognostic significance and shall pose challenges to its clinical implementation.

Pathogenesis of hepatocellular carcinoma according to aetiology

Hepatocellular carcinoma is related to various etiologies including hepatitis B, hepatitis C, high alcohol intake, aflatoxin B1 and metabolic syndrome. Most of the time HCC developed on cirrhosis. Consequently, the mechanisms of carcinogenesis of these different risk factors are difficult to separate from the events leading to cirrhosis. In contrast, aflatoxin B1 and hepatitis B have a clear direct oncogenic role through point mutations in the TP53 tumour suppressor gene and insertional mutagenesis respectively. Finally, next-generation sequencing and transcriptome analysis will refine our knowledge of the relationship between aetiology and the genetic events that draw the mutational landscape of hepatocellular carcinoma.

The collagen triple helix repeat containing 1 facilitates hepatitis B virus-associated hepatocellular carcinoma progression by regulating multiple cellular factors and signal cascades

Hepatitis B virus (HBV) infection is one of the major causes of acute and chronic liver diseases, fulminant hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). HCC accounts for more than 85% of primary liver cancers and is the seventh most common cancer and the third leading cause of cancer-related deaths. However, the mechanism by which HBV induces HCC is largely unknown. Collagen triple helixes repeat containing 1 (CTHRC1) is a secreted protein and has characteristics of a circulating hormone with potentially broad implications for cell metabolism and physiology. CTHRC1 is associated with human cancers, but its effect on HCC is unknown. Here, we revealed that CTHRC1 expression is highly correlated with HCC progression in HBV-infected patients, and demonstrated that HBV stimulates CTHRC1 expression by activating nuclear factor-kappa B (NF-κB) and cAMP response element binding protein (CREB), through extracellular signal-regulated kinase/c-Jun N-terminal kinase (ERK/c-JNK) pathway. In addition, CTHRC1 activates hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) through regulating phosphoinosmde-3-kinase/protein kinase B/mammalian target of rapamycin (PI-3K/AKT/mTOR) pathway. More interestingly, CTHRC1 enhances colony formation, migration, and invasion of hepatoma cells by regulating p53 and stimulating matrix metalloproteinase-9 (MMP-9) expression. In addition, knock-down of CTHRC1 results in the repression of HBV-associated carcinogenesis in nude mice. Thus, we revealed a novel mechanism by which HBV facilitates HCC development through activating the oncoprotein CTHRC1, which in turn enhances HBV-related HCC progression by stimulates colony formation, migration, and invasion of hepatoma cells through regulating multiple cellular factors and signal cascades.

The Tudor domain protein Spindlin1 is involved in intrinsic antiviral defense against incoming hepatitis B Virus and herpes simplex virus type 1

Hepatitis B virus infection (HBV) is a major risk factor for the development of hepatocellular carcinoma. HBV replicates from a covalently closed circular DNA (cccDNA) that remains as an episome within the nucleus of infected cells and serves as a template for the transcription of HBV RNAs. The regulatory protein HBx has been shown to be essential for cccDNA transcription in the context of infection. Here we identified Spindlin1, a cellular Tudor-domain protein, as an HBx interacting partner. We further demonstrated that Spindlin1 is recruited to the cccDNA and inhibits its transcription in the context of infection. Spindlin1 knockdown induced an increase in HBV transcription and in histone H4K4 trimethylation at the cccDNA, suggesting that Spindlin1 impacts on epigenetic regulation. Spindlin1-induced transcriptional inhibition was greater for the HBV virus deficient for the expression of HBx than for the HBV WT virus, suggesting that HBx counteracts Spindlin1 repression. Importantly, we showed that the repressive role of Spindlin1 is not limited to HBV transcription but also extends to other DNA virus that replicate within the nucleus such as Herpes Simplex Virus type 1 (HSV-1). Taken together our results identify Spindlin1 as a critical component of the intrinsic antiviral defense and shed new light on the function of HBx in HBV infection.

Sorafenib overcomes the chemoresistance in HBx-expressing hepatocellular carcinoma cells through down-regulation of HBx protein stability and suppresses HBV gene expression

Previous studies have revealed that HBx expression has anti-apoptotic effects, resulting in increased drug resistance in HCC cells. Thus, we examined if sorafenib efficiently induces apoptosis in HBx-overexpressing HCC cells. Noticeably, sorafenib efficiently induced apoptosis, even in HBx-expressing HepG2 cells, indicating that the HBx protein does not attenuate sorafenib-induced apoptosis. We next investigated if sorafenib modulates autophagy, allowing HCC cells to overcome the chemoresistance conferred by the HBx protein. Although autophagy plays a cytoprotective role against sorafenib-induced lethality, sorafenib was effective irrespective of HBx protein overexpression. We next examined if sorafenib exerts its cytotoxic effect via direct effects on the HBx protein. Importantly, sorafenib decreased HBx protein stability through a proteasome-dependent degradation pathway. Moreover, sorafenib decreased HBV gene expression and viral promoter activity. Taken together, sorafenib efficiently induces apoptotic cell death in HBx-expressing HCC cells via the downregulation of the HBx protein, a key factor in the anti-cancer drug resistance observed in HBV-induced HCC.

Key elements of the RNAi pathway are regulated by hepatitis B virus replication and HBx acts as a viral suppressor of RNA silencing

The host-mediated RNAi pathways restrict replication of viruses in plant, invertebrate and vertebrate systems. However, comparatively little is known about the interplay between RNAi and various viral infections in mammalian hosts. We show in the present study that the siRNA-mediated silencing of Drosha, Dicer and Ago2 [argonaute RISC (RNA-induced silencing complex) catalytic component 2] transcripts in Huh7 cells resulted in elevated levels of HBV (hepatitis B virus)-specific RNAs and, conversely, we observed a decrease in mRNA and protein levels of same RNAi components in HepG2 cells infected with HBV. Similar reductions were also detectable in CHB (chronic hepatitis B) patients. Analysis of CHB liver biopsy samples, with high serum HBV DNA load (>log108 IU/ml), revealed a reduced mRNA and protein levels of Drosha, Dicer and Ago2. The low expression levels of key RNAi pathway components in CHB patient samples as well as hepatic cells established a link between HBV replication and RNAi components. The HBV proteins were also examined for RSS (RNA-silencing suppressor) properties. Using GFP-based reversion of silencing assays, in the present study we found that HBx is an RSS protein. Through a series of deletions and substitution mutants, we found that the full-length HBx protein is required for optimum RSS activity. The in vitro dicing assays revealed that the HBx protein inhibited the human Dicer-mediated processing of dsRNAs into siRNAs. Together, our results suggest that the HBx protein might function as RSS to manipulate host RNAi defence, in particular by abrogating the function of Dicer. The present study may have implications in the development of newer strategies to combat HBV infection.

Hepatitis B virus X protein inhibits tumor suppressor miR-205 through inducing hypermethylation of miR-205 promoter to enhance carcinogenesis

The infection of hepatitis B virus (HBV) is closely associated with the development of hepatocellular carcinoma (HCC), in which HBV X protein (HBx) plays crucial roles. MicroRNAs are involved in diverse biologic functions and in carcinogenesis by regulating gene expression. In the present study, we aim to investigate the underlying mechanism by which HBx enhances hepatocarcinogenesis. We found that miR-205 was downregulated in 33 clinical HCC tissues in comparison with adjacent noncancerous hepatic tissues. The expression levels of miR-205 were inversely correlated with those of HBx in abovementioned tissues. Then, we demonstrated that HBx was able to suppress miR-205 expression in hepatoma and liver cells. We validated that miR-205 directly targeted HBx mRNA. Ectopic expression of miR-205 downregulated HBx, whereas depletion of endogenous miR-205 upregulated HBx in hepatoma cells. Notably, our data revealed that HBx downregulated miR-205 through inducing hypermethylation of miR-205 promoter in the cells. In terms of function, the forced miR-205 expression remarkably inhibited the HBx-enhanced proliferation of hepatoma cells in vitro and in vivo, suggesting that miR-205 is a potential tumor-suppressive gene in HCC. HBx-transgenic mice showed that miR-205 was downregulated in the liver. Importantly, HBx was able to abrogate the effect of miR-205 on tumor suppression in carcinogenesis. Therefore, we conclude that HBx is able to inhibit tumor suppressor miR-205 to enhance hepatocarcinogenesis through inducing hypermethylation of miR-205 promoter during their interaction. Therapeutically, miR-205 may be useful in the treatment of HCC.

Prevention of hepatocellular carcinoma in patients with chronic hepatitis B

Patients with chronic hepatitis B are at significant risk for hepatocellular carcinoma (HCC). Globally, over half a million people each year are diagnosed with HCC, with marked geographical variations. Despite overwhelming evidence for a causal role of hepatitis B virus (HBV) infection in the development of HCC and a well-established relationship between high baseline hepatitis B viral load and cumulative risk of HCC, the molecular basis for this association has not been fully elucidated. In addition, a beneficial role for antiviral therapy in preventing the development of HCC has been difficult to establish. This review examines the biological and molecular mechanisms of HBV-related hepatocarcinogenesis, recent results on the effect of modern nucleos(t)ides on the rate of HCC development in high risk HBV cohorts and the potential mechanisms by which long-term antiviral therapy with potent inhibitors of HBV replication might reduce the risk of HCC in patients with chronic hepatitis B. Although evidence from randomized controlled trials shows the favourable effects of antiviral agents in achieving profound and durable suppression of HBV DNA levels while improving liver function and histology, robust evidence of other long-term clinical outcomes, such as prevention of HCC, are limited.

Virtual screening of natural inhibitors to the predicted HBx protein structure of Hepatitis B Virus using molecular docking for identification of potential lead molecules for liver cancer

The HBx protein in Hepatitis B Virus (HBV) is a potential target for anti-liver cancer molecules. Therefore, it is of interest to screen known natural compounds against the HBx protein using molecular docking. However, the structure of HBx is not yet known. Therefore, the predicted structure of HBx using threading in LOMET was used for docking against plant derived natural compounds (curcumin, oleanolic acid, resveratrol, bilobetin, luteoline, ellagic acid, betulinic acid and rutin) by Molegro Virtual Docker. The screening identified rutin with binding energy of -161.65 Kcal/mol. Thus, twenty derivatives of rutin were further designed and screened against HBx. These in silico experiments identified compounds rutin01 (-163.16 Kcal/mol) and rutin08 (- 165.76 Kcal/mol) for further consideration and downstream validation.

Hepatitis B Virus-Related Hepatocellular Carcinoma: Pathogenic Mechanisms and Novel Therapeutic Interventions

BACKGROUND

Infection with the hepatitis B virus (HBV) is one of most important risk factors for hepatocellular carcinoma (HCC). Indeed, HBV is considered a group 1 human carcinogen and is a highly oncogenic agent. HBV cannot be effectively controlled or completely eliminated, so chronic HBV infection is a public health challenge worldwide.

SUMMARY

It is now believed that HBV-induced HCC involves a complex interaction between multiple viral and host factors. Many factors contribute to HBV-associated HCC, including products of HBV, viral integration and mutation, and host susceptibility. This review outlines the main pathogenic mechanisms with a focus on those that suggest novel targets for the prevention and treatment of HCC.

KEY MESSAGE

HBV infection is an important risk factor for HCC. Understanding the interaction between viral and host factors in HBV-induced HCC will reveal potential targets for future therapies.

PRACTICAL IMPLICATIONS

The two main therapeutic strategies consist of antiviral agents and immunotherapy-based approaches. Dendritic cell-based immunotherapy is promising for restoring the T cell-mediated antiviral immune response. Another approach is the specific expansion of the host's pool of HBV-specific T cells. Stimulation of the Toll-like receptors (TLRs), particularly TLR9, provides another means of boosting the antiviral response. Combination therapy with cytokines (interferon gamma and tumor necrosis factor alpha) plus lamivudine is more effective than these agents used alone. Therapeutic vaccines are being developed as an alternative to long-term antiviral treatment or as an adjunct.

Distinctive pharmacological differences between liver cancer cell lines HepG2 and Hep3B

As cellular models for in vitro liver cancer and toxicity studies, HepG2 and Hep3B are the two most frequently used liver cancer cell lines. Because of their similarities they are often treated as the same in experimental studies. However, there are many differences that have been largely over-sighted or ignored between them. In this review, we summarize the differences between HepG2 and Hep3B cell lines that can be found in the literature based on PubMed search. We particularly focus on the differential gene expression, differential drug responses (chemosensitivity, cell cycle and growth inhibition, and gene induction), signaling pathways associated with these differences, as well as the factors in governing these differences between HepG2 and Hep3B cell lines. Based on our analyses of the available data, we suggest that neither HBx nor p53 may be the crucial factor to determine the differences between HepG2 and Hep3B cell lines although HBx regulates the expression of the majority of genes that are differentially expressed between HepG2 and Hep3B. Instead, the different maturation stages in cancer development of the original specimen between HepG2 and Hep3B may be responsible for the differences between them. This review provides insight into the molecular mechanisms underlying the differences between HepG2 and Hep3B and help investigators especially the beginners in the areas of liver cancer research and drug metabolism to fully understand, and thus better use and interpret the data from these two cell lines in their studies.

Four homoisoflavonoids isolated from traditional Chinese medicine: "gan luo xin"

Two new homoisoflavonoids, ( ± )-5,7-dihydroxy-8-methyl-3-(2',4'-dihydroxybenzyl) chroman-4-one (1) and ( ± )-5,7-dihydroxy-6,8-dimethyl-3-(2',4'-dihydroxybenzyl) chroman-4-one (2), along with two known homoisoflavonoids, 5,7-dihydroxy-6-methyl-3-(2',4'-dihydroxybenzyl)chroman-4-one (3) and disporopsin (4), were isolated from the EtOAc extract of traditional Chinese medicine--"Gan Luo Xin." Their structures were determined on the basis of spectroscopic analysis (UV, IR, HR-ESI-MS, 1D NMR, and 2D NMR).

Infected hematopoietic stem cells and with integrated HBV DNA generate defective T cells in chronic HBV infection patients

A weak T-cell response plays a key role in the persistence of hepatitis B virus (HBV) infection. We aimed to confirm that T-cell defects in patients with chronic HBV infection are associated with HBV DNA infection of bone marrow (BM) hematopoietic stem cells (HSCs). Using reverse transcription polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH), we observed the transcription of HBsAg coding genes and confirmed the integration of HBV DNA in CD34(+) BM HSCs from chronic HBV infection patients. T cells were generated by coculturing the HSCs with delta-like ligand 1-expressing OP9 (OP9-DL1) cells. The phenotypes of the T cells were then evaluated by flow cytometric (FACS) analysis on days 14 and 25. The results demonstrated that fewer CD3(+) TCRaβ(+) CD3(+) CD4(+) and CD4(+) CD8(+) T cells were generated from the HSCs of the patients than from the healthy controls, (P < 0.01) but the frequency of CD3(+) D8(+) T cells was not significantly different between the two group (P > 0.05). In contrast, CD4(+) CD25(+) T cells were more in the patient group than in healthy controls (P < 0.01) on both days 14 and 25. There were fewer CD3(+) CD4(+) /CD3(+) CD8(+) cells in the patient group than in the healthy control group on day 25 (P < 0.05). Less proliferation and lower levels of IL-2 and IFN- γ were also observed in the patient group compared with the control group (P < 0.05).These data suggest that HBV DNA infected and integrated into the BM HSCs from patients with chronic HBV infection and that these BM HSCs generated defective T cells.

Mortality, liver transplantation, and hepatocellular carcinoma among patients with chronic hepatitis B treated with entecavir vs lamivudine

BACKGROUND & AIMS

Little is known about whether the antiviral agent entecavir is more effective than a less potent drug, lamivudine, in reducing the risk of death and hepatocellular carcinoma (HCC) in patients with chronic hepatitis B.

METHODS

We performed a retrospective analysis of data from 5374 consecutive adult patients with chronic hepatitis B, treated with entecavir (n = 2000) or lamivudine (n = 3374), at a tertiary referral hospital in Seoul, Korea, from November 1, 1999, through December 31, 2011. Data were collected from patients for up to 6 years and analyzed by a multivariable Cox proportional hazards model for the entire cohort and for propensity score-matched cohorts.

RESULTS

During the study period, 302 patients (5.6%) died, 169 (3.1%) received a liver transplant, and 525 (9.8%) developed HCC. Multivariable analyses showed that compared with lamivudine, entecavir therapy was associated with a significantly lower risk of death or transplantation (hazard ratio [HR], 0.49; 95% confidence interval [CI], 0.38-0.64), but a similar risk of HCC (HR, 1.08; 95% CI, 0.87-1.34). In the 1792 overall propensity-matched pairs, entecavir again was associated with a significantly lower risk of death or transplantation (HR, 0.49; 95% CI, 0.37-0.64) and a similar risk of HCC (HR, 1.01; 95% CI, 0.80-1.27). Entecavir also reduced the risk of death or transplantation, compared with lamivudine, in 860 pairs of patients with cirrhosis (HR, 0.42; 95% CI, 0.31-0.57) but there were no differences in risk for HCC (HR, 1.00; 95% CI, 0.78-1.28). However, entecavir and lamivudine did not have significantly different effects on clinical outcome in 878 pairs of patients without cirrhosis.

CONCLUSIONS

In a retrospective study of 5374 patients with chronic hepatitis B virus infection, entecavir therapy was associated with a significantly lower risk of death or transplantation than lamivudine. However, the drugs did not have different effects on HCC risk.

Cyclin D2 plays a regulatory role in HBV replication

Hepatitis B virus (HBV) infection is the leading cause of liver diseases. However, the molecular mechanisms of HBV infection and carcinogenesis have not been fully elucidated. In this study, we found that cyclin D2 was upregualted in HBV-expressing cells and liver tissues of HBV-transgenic mice. Gene silencing of cyclin D2 inhibited HBV DNA replicative intermediates, 3.5 kb mRNA, core protein level, as well as the secretions of HBsAg and HBeAg. On the contrary, overexpression of cyclin D2 promoted HBV replication. Furthermore, cyclin D2 regulated HBV replication by enhancing the activity of HBV core and Sp1 promoters by targeting transcription factor CREB2. Silencing of CREB2 abolished enhancement of HBV replication induced by cyclin D2. Together, our study has uncovered a positive role of cyclin D2 in HBV replication. It is conceivable that therapeutic application of cyclin D2 inhibitor in HBV infection therapy.

Exploration of liver cancer genomes

Liver cancer is the third leading cause of cancer-related death worldwide. Advances in sequencing technologies have enabled the examination of liver cancer genomes at high resolution; somatic mutations, structural alterations, HBV integration, RNA editing and retrotransposon changes have been comprehensively identified. Furthermore, integrated analyses of trans-omics data (genome, transcriptome and methylome data) have identified multiple critical genes and pathways implicated in hepatocarcinogenesis. These analyses have uncovered potential therapeutic targets, including growth factor signalling, WNT signalling, the NFE2L2-mediated oxidative pathway and chromatin modifying factors, and paved the way for new molecular classifications for clinical application. The aetiological factors associated with liver cancer are well understood; however, their effects on the accumulation of somatic changes and the influence of ethnic variation in risk factors still remain unknown. The international collaborations of cancer genome sequencing projects are expected to contribute to an improved understanding of risk evaluation, diagnosis and therapy for this cancer.

Dissecting the pleiotropic actions of HBx mutants against hypoxia in hepatocellular carcinoma

Error-prone integration of the hepatitis B virus X protein (HBx) into the hepatocellular genome generates a multitude of mutants exerting diverse effects on the development and progression of hepatocellular carcinoma (HCC). A recent study by Lai and colleagues revealed the disparate regulatory activity of clinically-predominant HBx mutants towards hypoxia-inducible factor-1α (HIF-1α), a central regulator of tumor angiogenesis, proliferation, metastasis and differentiation. These findings have shed insight into specific viral contribution of hypoxic response during hepatocarcinogenesis.

mTOR in viral hepatitis and hepatocellular carcinoma: function and treatment

As the fifth most common cancer in men and the eighth most common cancer in women, hepatocellular carcinoma (HCC) is the leading cause of cancer-related deaths worldwide, with standard chemotherapy and radiation being minimally effective in prolonging survival. Virus hepatitis, particularly HBV and HCV infection is the most prominent risk factor for HCC development. Mammalian target of rapamycin (mTOR) pathway is activated in viral hepatitis and HCC. mTOR inhibitors have been tested successfully in clinical trials for their antineoplastic potency and well tolerability. Treatment with mTOR inhibitor alone or in combination with cytotoxic drugs or targeted therapy drug scan significantly reduces HCC growth and improves clinical outcome, indicating that mTOR inhibition is a promising strategy for the clinical management of HCC.

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.