Renal grafts from anti-hepatitis B core-positive donors: a quantitative review of the literature.

BACKGROUNDS AND AIMS: Organ shortage is a major problem in transplantation. The use of organs from hepatitis B surface antigen (HBsAg)-negative and hepatitis B core antibody (HBcAb)-positive donors could significantly increase the donor pool. However, little information is available about the impact of HBcAb status of renal donors on viral transmission to recipients. To address this issue, the present quantitative review of relevant studies has been performed. MATERIALS AND METHODS: Electronic databases including Medline, EMBASE, ISI, and Scopus were systematically searched for studies that evaluated risk of hepatitis B virus (HBV) transmission through renal transplantation from HBsAg-/HBcAb+ donors. Eligible studies were identified according to predefined criteria. The final outcome was one of HBV markers seroconversion defined as HBsAg, hepatitis B surface antibody (HBsAb), or HBcAb detection in previously seronegative end-stage renal disease (ESRD) patients after transplantation, and without other identified major sources of infection. RESULTS: Nine studies with 1385 eligible kidney recipients were included. In total, 45 subjects showed seroconversion of HBV markers as follows: HBsAg (n = 4) (0.28%; 95% confidence interval [CI] 0.006; 0.57), HBcAb (n = 32), HBsAb (n = 5), and either HBcAb or HBsAb (n = 4). The total rate of seroconversion after renal transplantation was calculated to be 3.24% (95% CI: 2.31-4.18). CONCLUSION: Our review indicates that the risk of HBV transmission from HBcAb-positive kidney donors is extremely low. Therefore, kidneys from these donors can be transplanted safely into ESRD patients.

Weight loss and severe jaundice in a patient with hyperthyroidism.

BACKGROUND: Thyrotoxicosis may significantly alter hepatic function and is associated with autoimmune disorders of the liver. CASE REPORT: We report the case of a thyrotoxic patient with Graves' disease and histologically established cholestatic hepatitis. Medical treatment of hyperthyroidism normalized liver function tests. CONCLUSIONS: In patients with elevated liver function parameters and jaundice of unknown origin, thyroid function should generally be tested. Moreover, medical treatment of hyperthyroidism with thyrostatics may cause severe hepatitis whereas untreated hyperthyroid patients are at risk of developing chronic liver failure.

New aspects of an anti-tumour drug: sorafenib efficiently inhibits HCV replication.

BACKGROUND AND AIMS: Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and is associated with significant morbidity and mortality. Since there is evidence for an interaction of NS5A with c-Raf we studied whether the c-Raf inhibitor sorafenib affects HCV replication. METHODS: HCV replicating HuH7.5 cells were treated with sorafenib and examined for HCV RNA titres by northern blotting or real time polymerase chain reaction (PCR), for core, NS3 and NS5A expression by immunostaining, and for replication by luciferase reporter assays. RESULTS: Here we demonstrate that in cells replicating infectious HCV particles, NS5A recruits c-Raf to the replicon complex resulting in the activation of c-Raf. Therefore, we studied the effect of inhibition of c-Raf on HCV replication using the anti-tumour drug sorafenib that is known to inhibit c-Raf with high specificity. Sorafenib efficiently blocks HCV replication and viral gene expression. In addition, in HCV-replicating cells sorafenib decreased the hyperphosphorylated form of NS5A and resulted in the formation of additional hypophosphorylated forms. Further, sorafenib caused a rapid dissociation of lipid droplets. We provide evidence that the antiviral effect of sorafenib indeed is caused by inhibition of c-Raf. By contrast, inhibition of targets downstream of c-Raf or inhibition of tyrosine kinases by sunitinib did not affect HCV replication. CONCLUSION: Our data demonstrate that the well-characterised anti-tumour drug sorafenib efficiently blocks HCV replication in vitro. This novel effect of sorafenib should be further explored as an antiviral strategy for patients with chronic HCV infection.

Somatic gene editing ameliorates skeletal and cardiac muscle failure in pig and human models of Duchenne muscular dystrophy.

Frameshift mutations in the DMD gene, encoding dystrophin, cause Duchenne muscular dystrophy (DMD), leading to terminal muscle and heart failure in patients. Somatic gene editing by sequence-specific nucleases offers new options for restoring the DMD reading frame, resulting in expression of a shortened but largely functional dystrophin protein. Here, we validated this approach in a pig model of DMD lacking exon 52 of DMD (DMDΔ52), as well as in a corresponding patient-derived induced pluripotent stem cell model. In DMDΔ52 pigs1, intramuscular injection of adeno-associated viral vectors of serotype 9 carrying an intein-split Cas9 (ref. 2) and a pair of guide RNAs targeting sequences flanking exon 51 (AAV9-Cas9-gE51) induced expression of a shortened dystrophin (DMDΔ51-52) and improved skeletal muscle function. Moreover, systemic application of AAV9-Cas9-gE51 led to widespread dystrophin expression in muscle, including diaphragm and heart, prolonging survival and reducing arrhythmogenic vulnerability. Similarly, in induced pluripotent stem cell-derived myoblasts and cardiomyocytes of a patient lacking DMDΔ52, AAV6-Cas9-g51-mediated excision of exon 51 restored dystrophin expression and amelioreate skeletal myotube formation as well as abnormal cardiomyocyte Ca2+ handling and arrhythmogenic susceptibility. The ability of Cas9-mediated exon excision to improve DMD pathology in these translational models paves the way for new treatment approaches in patients with this devastating disease.

CpG-island methylation of the ER promoter in colorectal cancer: analysis of micrometastases in lymph nodes from UICC stage I and II patients.

Patients with UICC stage II colorectal cancer (CRC) have a risk of approximately 20% to develop disease recurrence after tumour resection. The presence and significance of micrometastases for locoregional recurrence in these patients lacking histopathological lymph node involvement on routine stained HE sections is undefined. Oestrogen receptor (ER) promoter methylation has earlier been identified in CRC. Therefore, we evaluated the methylation status of the ER promoter in lymph nodes from 49 patients with CRC UICC stage I and II as a molecular marker of micrometastases and predictor of local recurrence. DNA from 574 paraffin-embedded lymph nodes was isolated and treated with bisulphite. For the detection of methylated ER promoter sequences, quantitative real-time methylation-specific PCR was used. Of the 49 patients tested, 15 (31%) had ER methylation-positive lymph nodes. Thirteen of those (86%) remained disease free and two (14%) developed local recurrence. In the resected lymph nodes of 34 of the 49 patients (69%), no ER promoter methylation could be detected and none of these patients experienced a local relapse. The methylation status of the ER promoter in lymph nodes of UICC stage I and II CRC patients may be a useful marker for the identification of patients at a high risk for local recurrence.

Angular invariants in developing human mandibles.

Recent studies of lateral cephalograms based on symmetric-axis analyses of the mandibular border yield angles that appear to be uninfluenced by gross changes in mandibular shape over age and between individuals.

Detection of two viral genomes in single cells by double-label hybridization in situ and color microradioautography.

Double labeling and color microradioautography were used in a new method of hybridization in situ to identify different genes in individual cells. The method is based on the unequal penetration of 3H and 35S into two layers of nuclear track emulsion separated by a thin barrier film. Hybridization of a 35S-labeled probe specific for one kind of gene results in silver grains over cells in both layers of emulsion; a 3H-labeled probe for a second gene provides grains only in the first layer of emulsion. Silver grains are converted to magenta-colored grains in the first layer and to cyan-colored grains in the second to facilitate enumeration of grains in each layer. This technique should be widely applicable in analyses of differential gene expression in single cells or in discrete populations of cells.

Performance and metabolic and endocrine changes with emphasis on glucose metabolism in high-yielding dairy cows with high and low fat content in liver after calving.

Elevated liver fat content occurs in high-yielding dairy cows during the transition from pregnancy to lactation after fat mobilization and may affect hepatic glucose metabolism, but the degree of liver fat storage is highly variable. Therefore, we studied metabolic and endocrine changes and hepatic glucose metabolism in cows that markedly differ in liver fat content. Multiparous cows from the same herd with high (HFL; n = 10) and low (LFL; n = 10) liver fat contents (mean of d 1, 10, and 21 after calving for each cow, respectively) were studied from 60 d before expected calving to 56 d in milk. Cows were fed ad libitum and all cows received the same diets. Liver samples were taken on d 1, 10, and 21 after calving; mean fat content (+/-SEM) in liver of HFL cows was 174 +/- 9.6 mg/g, whereas mean liver fat content in LFL cows was 77 +/- 3.3 mg/g. Blood samples were taken 20 and 7 d before expected calving and 0, 7, 14, 28, and 56 d after calving to measure plasma concentrations of nonesterified fatty acids, beta-hydroxybutyrate, glucose, insulin, glucagon, insulin-like growth factor-I, and leptin. In liver, glycogen content as well as mRNA levels of phosphoenolpyruvate carboxykinase, pyruvate carboxylase, glucose-6-phosphatase, and glucose transporter were measured by quantitative real-time PCR. Back fat thickness decreased and dry matter intake increased with onset of lactation, and back fat thickness was higher but dry matter intake was lower in HFL than in LFL. Energy-corrected milk yield did not differ between groups, but milk fat content was higher and lactose content was lower in HFL than LFL at the beginning of lactation. Energy balance was more negative in HFL than in LFL. Plasma nonesterified fatty acids and beta-hydroxybutyrate concentrations increased and plasma glucose concentration tended to decrease more in HFL than LFL with onset of lactation. Glucagon to insulin ratios increased more in HFL than LFL with onset of lactation. Hepatic glycogen content was higher in LFL than HFL, whereas mRNA levels of glucose-6-phosphatase and pyruvate carboxylase were higher in HFL than in LFL, and cytosolic phosphoenolpyruvate carboxykinase mRNA level increased similarly after parturition in both groups. In conclusion, an elevated liver fat content was related to greater fat mobilization and reduced feed intake and was associated with effects on hepatic glucose metabolism. As environment and feeding management were the same, individual cow factors were responsible for differences in energy metabolism during the transition period.

An error model for protein quantification.

MOTIVATION: Quantitative experimental data is the critical bottleneck in the modeling of dynamic cellular processes in systems biology. Here, we present statistical approaches improving reproducibility of protein quantification by immunoprecipitation and immunoblotting. RESULTS: Based on a large data set with more than 3600 data points, we unravel that the main sources of biological variability and experimental noise are multiplicative and log-normally distributed. Therefore, we suggest a log-transformation of the data to obtain additive normally distributed noise. After this transformation, common statistical procedures can be applied to analyze the data. An error model is introduced to account for technical as well as biological variability. Elimination of these systematic errors decrease variability of measurements and allow for a more precise estimation of underlying dynamics of protein concentrations in cellular signaling. The proposed error model is relevant for simulation studies, parameter estimation and model selection, basic tools of systems biology. AVAILABILITY: Matlab and R code is available from the authors on request. The data can be downloaded from our website www.fdm.uni-freiburg.de/~ckreutz/data.

Transcriptome studies of bovine endometrium reveal molecular profiles characteristic for specific stages of estrous cycle and early pregnancy.

The endometrium undergoes marked functional changes during estrous cycle and pregnancy. As the adjacent environment of the conceptus, it represents the maternal interface for embryo-maternal communication, which is essential to maintain pregnancy. Transcriptome studies provide the unique opportunity to assess molecular profiles changing in response to endocrine or metabolic stimuli or to embryonic pregnancy recognition signals. Here we review the current state of transcriptome profiling techniques and the results of a series of transciptome studies comparing bovine endometrium samples during the estrous cycle or endometrium samples from pregnant vs. non-pregnant animals. These studies revealed specific mRNA profiles which are characteristic for the functional status of the endometrium. Transcriptome studies of endometrial samples recovered during the pre-attachment period identified many interferon-stimulated genes, genes that are possibly involved in embryo-maternal immune modulation ( C1S, C1R, C4, SERPING1, UTMP, CD81, IFITM1, BST2), as well as genes affecting cell adhesion ( AGRN, CD81, LGALS3BP, LGALS9, GPLD1, MFGE8, and TGM2) and remodeling of the endometrium ( CLDN4, MEP1B, LGMN, MMP19, TIMP2, TGM2, MET, and EPSTI1). The results of these transcriptome studies were compared to those of similar microarray analyses in human, mouse and Rhesus monkey to identify similarities in endometrial biology between mammalian species and species-specific differences. Future studies will cover dynamic transcriptome changes between different stages of early pregnancy, the relationship between metabolic problems in dairy cows and the functionality of reproductive tissues as well as endometrium transcriptome profiles in recipients of somatic cell nuclear transfer embryos.

The molecular biology of hepatitis B virus.

Infection with the hepatitis B virus (HBV) or related hepadnaviruses is associated with a wide spectrum of liver diseases, including hepatocellular carcinoma (HCC). In this article we review the current state of knowledge about the structure, genetic organization and life cycle of HBV. The mechanisms of viral pathogenesis and HCC development remain poorly understood, but new approaches may soon begin to shed light on these areas.

Cyclin D1 overexpression and p53 inactivation immortalize primary oral keratinocytes by a telomerase-independent mechanism.

The immortalization of human cells is a critical step in multistep carcinogenesis. Oral-esophageal carcinomas, a model system to investigate molecular mechanisms underlying squamous carcinogenesis, frequently involve cyclin D1 overexpression and inactivation of the p53 tumor suppressor. Therefore, our goal was to establish the functional role of cyclin D1 overexpression and p53 inactivation in the immortalization of primary human oral squamous epithelial cells (keratinocytes) as an important step toward malignant transformation. Cyclin D1 overexpression alone was found to induce extension of the replicative life span of normal oral keratinocytes, whereas the combination of cyclin D1 overexpression and p53 inactivation led to their immortalization. This study also demonstrates that immortalization of oral keratinocytes can be independent of telomerase activation, involving an alternative pathway of telomere maintenance (ALT).

Reversal of drug resistance of hepatocellular carcinoma cells by adenoviral delivery of anti-ABCC2 antisense constructs.

Human cancers are characterized by a high degree of drug resistance. The multidrug resistance transporters MDR1-P-glycoprotein (ABCB1) and ABCC2 (MRP2) are expressed in a variety of human cancers, including hepatocellular carcinoma (HCC). The ABCC2 gene encodes a membrane protein involved in the ATP-dependent transport of conjugates of lipophilic substances. In this study we analyzed the effect of an ABCC2 antisense construct on the chemosensitization of HepG2 cells. Adenoviral vectors were constructed to allow an efficient expression of anti-ABCC2 antisense constructs. The effective target sequence comprised nucleotides 2543-2942 of the human ABCC2 cDNA. Adenoviral delivery of the ABCC2 antisense construct resulted in a reduced IC(50) for doxorubicin (12-fold), vincristine (50-fold), cisplatin (25-fold) and etoposide (VP-16) (25-fold). The adenoviral delivery of the ABCC2 antisense construct was so efficient that chemosensitization of HepG2 cells could even be demonstrated in mass cell cultures without a selection of transduced cells for single ABCC2 antisense-expressing HCC cell clones. After transfection of the ABCC2 antisense-expressing construct, HepG2 cells had significantly reduced ABCC2 mRNA and ABCC2 protein levels. Transduction of the ABCC2 antisense-expressing construct into HepG2 cells resulted in the accumulation of the high-affinity ABCC2 substrate Fluo-3. HepG2 tumors stably transfected with an anti-ABCC2 antisense construct regressed significantly in nude mice upon vincristine treatment. In addition, significant tumor regression was also observed when adenovirus-expressing anti-ABCC2 antisense construct was directly injected into HepG2 tumors in nude mice. Our study demonstrates the specific reversal of ABCC2-related drug resistance in adenovirus-transduced HepG2 cells and in HepG2 tumors in nude mice expressing this ABCC2 antisense construct.

CD117 (c-kit) expression in human hepatocellular carcinoma.

AIMS: Although various methods of treatment have been tried, treatment options for advanced hepatocellular carcinoma (HCC) remain limited. Expression of the platelet-derived growth factor has been shown in HCC, which may derive from hepatic stem cells that express the c-kit proto-oncogene. Because of the promising results of imatinib and the key role played by c-kit in gastrointestinal stromal tumours and other solid tumours, the aim of this study was to determine the prevalence of c-kit (CD117) overexpression in patients with HCC. MATERIALS AND METHODS: A retrospective study of 258 archival specimens of subjects with histologically confirmed HCC was carried out. Expression of the c-kit proto-oncogene was evaluated by immunohistochemistry using rabbit anti-CD117 antibody A4502. RESULTS: The overall percentage of positive immunohistochemical staining of HCCs was 2.3% (6/258). CONCLUSIONS: Our results suggest that CD117 is not significantly overexpressed in HCC and there seems to be no role for the use of imatinib.

Technical note: Bovine oviduct and endometrium array version 1: a tailored tool for studying bovine endometrium biology and pathophysiology.

Fertility problems are the main reason for slaughter of high-performance milk cows, because elongated calving intervals result in financial losses for the farmer and retard genetic progress. Genetic improvement of fertility would be of great benefit, but functional traits for effective selection are missing. Recent advances in functional genomics tools like DNA microarrays could be the key to identify gene expression patterns in the endometrium that correlate with maternal fertility. Therefore, a first version of a bovine oviduct and endometrium cDNA array was established that contains a set of 1,440 cDNA clones and long oligonucleotides representing 950 different genes. The major part of these genes has been identified in a series of differential gene expression studies in endometrium (different stages of the estrous cycle, d 18 pregnant vs. nonpregnant) and in oviduct epithelial cells (different stages of the estrous cycle) using a combination of subtracted cDNA libraries and cDNA array hybridization. Furthermore, cDNA clones of genes, which showed no changes in their mRNA levels in the analyzed tissues, were added as controls. Reproducibility of the array hybridization, a comparison with the Affymetrix bovine genome array, and confirmation of differential gene expression with reverse transcription-quantitative PCR is shown. Potential future applications include systematic studies of interactions between metabolic status and functionality of the endometrium to identify genes that could be used for differential diagnosis of fertility problems. Further, endometrium transcriptome profiles may serve as novel traits to improve fertility by genetic selection.

Investigation of intra-herd spread of Mycobacterium caprae in cattle by generation and use of a whole-genome sequence.

Single nucleotide polymorphisms (SNPs) calculated from whole genome sequencing (WGS) are ideally suited to study evolutionary relationships of pathogens and their epidemiology. Mycobacterium caprae infections have been documented frequently in cattle and red deer along the Bavarian and Austrian Alps during the last decade. However, little is still known about the transmission within cattle holdings and possible alterations of the genomes of M. caprae during such events. The aim of this study was to study the molecular epidemiology of bovine tuberculosis (bTB) in selected herds based on isolate-specific genome-wide SNPs and to perform a phylogenetic network analysis. In total, 61 M. caprae isolates were collected originating from eight cattle farms over a period of twelve years between 2004 and 2015. Analysis of their sequence data revealed that the M. caprae isolates of an affected farm differ at all in a few SNPs. In contrast, many more SNPs were found when comparing the M. caprae genomes originating from different herds. The results demonstrated that the spread of bTB in the affected farms occurred by direct transmission between the members of each herd rather than between herds and a M. caprae introduction in farms after contact events e. g. on summer pastures can readily be traced by WGS analysis. Furthermore, we assembled a nearly complete whole genome sequence of M. caprae derived from several cattle isolates originating from bTB cases in the Bavarian Alpine region.

The Region of Difference Four is a Robust Genetic Marker for Subtyping Mycobacterium caprae Isolates and is Linked to Spatial Distribution of Three Subtypes.

Alpine Mycobacterium caprae isolates found in cattle and red deer display at least three genetic variations in the region of difference four (RD4) that can be used for further differentiation of the isolates into the subtypes 'Allgäu', 'Karwendel' and 'Lechtal'. Each genomic subtype is thereby characterized by a specific nucleotide deletion pattern in the 12.7-kb RD4 region. Even though M. caprae infections are frequently documented in cattle and red deer, little is known about the transmission routes. Hence, robust markers for M. caprae subtyping are needed to gain insight into the molecular epidemiology. For this reason, a rapid and robust multiplex PCR was developed for the simultaneous detection of three M. caprae RD4 subtypes and was used to subtype a total number of 241 M. caprae isolates from animals (145 cattle, 95 red deer and one fox) from Bavaria and Austria. All three subtypes occur spatially distributed and are found in cattle and in red deer suggesting transmission between the two species. As subtypes are genetically stable in both species it is hypothesized that the described genetic variations developed within the host due to 'within-host replication'. The results of this study recommend the genomic RD4 region as a reliable diagnostic marker for M. caprae subtype differentiation.

Effect of vardenafil, an inhibitor of phosphodiesterase-5, on portal haemodynamics in normal and cirrhotic liver -- results of a pilot study.

BACKGROUND: Dysregulation of the cyclic guanosine 3',5' monophosphate-nitric oxide system is in part responsible for portal hypertension in cirrhosis. AIM: To test the effects of inhibitors of phosphodiesterase-5 on portal haemodynamics. METHODS: To 18 healthy subjects and 18 patients with Child A liver cirrhosis, 10 mg of vardenafil, an inhibitor of phosphodiesterase-5, were administered orally. Doppler sonographic measurements of hepatic and splanchnic blood flow, systemic blood pressure and heart rate were recorded before, 1 h after, and 48 h after the application. Vardenafil plasma levels were determined after 1 h. In five patients, invasive registration of free and wedged hepatic vein pressure was performed. RESULTS: Portal venous flow increased in patients from 0.82 +/- 0.30 L/min (mean +/- s.d.) by 26% (CI: 16-37%, P = 0.0004) and in healthy subjects from 0.75 +/- 0.20 L/min (mean +/- s.d.) by 19% (CI: 9-28%; P = 0.0010). Celiac and hepatic artery resistivity indices rose significantly. Systemic blood pressure decreased slightly in patients. The wedged hepatic venous pressure gradient decreased in four of five patients with liver cirrhosis. Vardenafil plasma levels were higher in patients (14 +/- 10 microg/L) than in healthy subjects (9 +/- 6 microg/L; n.s.). CONCLUSIONS: Inhibition of phosphodiesterase-5 increases portal flow and lowers portal pressure by a decrease in sinusoidal resistance and may be a novel therapeutic strategy for portal hypertension.

Growth suppression of the hepatocellular carcinoma cell line Hepa1-6 by an activatable interferon regulatory factor-1 in mice.

Hepatocellular carcinoma (HCC) is a highly malignant tumor with a poor prognosis and few therapeutic options. The aim of the study was to evaluate the potential of IFN regulatory factor-1 (IRF-1) for cytokine gene therapy of HCC using an IRF-1/human estrogen receptor fusion protein (IRF-1hER), which is reversibly activatable by beta-estradiol (E2). IRF-1hER stably expressing murine Hepa1-6 HCC cells (HepaIRF-1hER) were characterized by lowMHC 1, highCD54, and lack of MHC II, CD80, and CD86 expression. Activation of HepaIRF-1hER cells induced a highMHC I, lowMHC II, and highCD54 phenotype. Furthermore, they were characterized by IFN-beta secretion, decreased anchorage-independent growth in a soft agar assay, and diminished cell growth. Tumor growth in E2-treated syngeneic C57L/J mice, but not in E2-untreated mice, was suppressed. These E2-treated mice were protected against rechallenge with HepaIRF-1hER and wild-type Hepa1-6 tumors even in the absence of E2, suggesting induction of tumor specific immunity. In fact, significant CTL activity against Hepa1-6 tumors and the endogenously expressed HCC-specific self antigen alpha-fetoprotein was observed. Antitumoral effects, however, were only partially dependent on both CD4+ and CD8+ T cells. IRF-1 treatment of mice bearing HepaIRF-1hER tumors resulted in growth arrest of tumors, and a significant survival benefit was observed in comparison to E2-untreated mice. In conclusion, our data demonstrate that IRF-1 suppresses HCC growth through both a direct antitumor growth effect and enhanced immune cell recognition of the tumor and is a promising candidate for gene therapy of HCC.

The transcription factor c-JUN/AP-1 promotes HBV-related liver tumorigenesis in mice.

Hepatocellular carcinoma (HCC) develops as a consequence of chronic inflammatory liver diseases such as chronic hepatitis B virus (HBV) infection. The transcription factor c-Jun/activator protein 1 (AP-1) is strongly expressed in response to inflammatory stimuli, promotes hepatocyte survival during acute hepatitis and acts as an oncogene during chemically induced liver carcinogenesis in mice. Here, we therefore aimed to characterize the functions of c-Jun during HBV-related liver tumorigenesis. To this end, transgenic mice expressing all HBV envelope proteins (HBV(+)), an established model of HBV-related HCC, were crossed with knockout mice lacking c-Jun specifically in hepatocytes and tumorigenesis was analyzed. Hepatic expression of c-Jun was strongly induced at several time points during tumorigenesis in HBV(+) mice, whereas expression of other AP-1 components remained unchanged. Importantly, formation of premalignant foci and tumors was strongly reduced in HBV(+) mice lacking c-Jun. This phenotype correlated with impaired hepatocyte proliferation and increased expression of the cell cycle inhibitor p21, whereas hepatocyte survival was not affected. Progression and prognosis of HBV-related HCC correlates with the expression of the cytokine osteopontin (Opn), an established AP-1 target gene. Opn expression was strongly reduced in HBV(+) livers and primary mouse hepatocytes lacking c-Jun, demonstrating that c-Jun regulates hepatic Opn expression in a cell-autonomous manner. These findings indicate that c-Jun has important functions during HBV-associated tumorigenesis by promoting hepatocyte proliferation as well as progression of dysplasia. Therefore, targeting c-Jun may be a useful strategy to prevent hepatitis-associated tumorigenesis.