Efficacy of additional radiofrequency ablation after transcatheter arterial chemoembolization for intermediate hepatocellular carcinoma.

AIM: For intermediate hepatocellular carcinoma (HCC), transcatheter arterial chemoembolization (TACE) therapy is recommended in the guidelines as a monotherapy, although TACE is a non-curative therapy. The aims of the present study were to evaluate the efficacy of adding radiofrequency ablation (RFA) to TACE in patients with intermediate HCC, and to identify the factors that were associated with favorable survival in these patients. METHODS: Fifty-nine patients with intermediate HCC were enrolled in this retrospective study. Thirty-nine patients were treated with TACE alone and 20 patients were treated with additional RFA after TACE. RESULTS: The recurrence-free survival rates at 0.5, 1 and 2 years for the additional RFA group were 32%, 19% and 13%, respectively, and these were significantly higher than those of the TACE group (8%, 3% and 0%, respectively; log-rank test, P = 0.001). The cumulative survival rates of the additional RFA group were significantly higher than those of the TACE group (log-rank test, P = 0.002), although this significant difference was not found in the subgroup of treatment naive patients because of small sample size. Multivariate analysis indicated male sex, lower total bilirubin, lower α-fetoprotein, lower des-γ-carboxyprothrombin, newly recurrent HCC nodules within the last 12 months and additional RFA as independent factors that were significantly associated with favorable overall survival. CONCLUSION: Additional RFA of nodules insufficiently treated by TACE is effective therapy for obtaining favorable disease-free survival in patients with intermediate HCC, and leads to better overall survival particularly in recurrent patients.

Impaired induction of interleukin 28B and expression of interferon λ 4 associated with nonresponse to interferon-based therapy in chronic hepatitis C.

BACKGROUND AND AIM: Interferon (IFN) λ plays an important role in innate immunity to protect against hepatitis C viral (HCV) infection. Single nucleotide polymorphisms (SNPs) near IL28B (IFNλ3) are strongly associated with treatment response to IFNα therapy in chronic hepatitis C (CHC) patients. Recently, IFNλ4 related to IL28B-unfavorable allele was discovered. However, the impact of IFNλs on CHC is unknown. We aimed to investigate the mechanism underlying responsiveness to IFN-based therapy in CHC associated with SNPs near IL28B. METHODS: We evaluated the basal mRNA levels and ex-vivo induction of IFNλ expression including IFNλ4 in peripheral blood mononuclear cells (PBMCs) from 50 CHC patients treated with pegylated-IFNα/RBV. Furthermore, we investigated the effect of IFNλ4 on induction of IL28B in vitro. RESULTS: When PBMCs were stimulated with IFNα and polyinosinic-polycytidylic acid, IL28B induction was significantly lower in patients with IL28B-unfavorable genotype (rs12979860 CT/TT) than those with IL28B-favorable genotype (rs12979860 CC; P=0.049). IL28B induction was lower in nonresponders than in relapsers (P = 0.04), and it was also lower in nonsustained virological responder patients for triple therapy including NS3 protease inhibitors. IFNλ4 mRNA was detected in 12 of 26 patients with IL28B-unfavorable SNP, and IFNλ4 expression was associated with lower IL28B induction in patients with IL28B-unfavorable genotype (P=0.04) and nonresponse to IFNα therapy (P=0.003). Overexpression of IFNλ4 suppressed IL28B induction and promoter activation. CONCLUSIONS: Impaired induction of IL28B, related to IFNλ4 expression in PBMCs of IL28B-unfavorable patients, is associated with nonresponse to IFNα-based therapy for hepatitis C viral infection.

Hepatitis C virus NS4B protein targets STING and abrogates RIG-I-mediated type I interferon-dependent innate immunity.

UNLABELLED: Hepatitis C virus (HCV) infection blocks cellular interferon (IFN)-mediated antiviral signaling through cleavage of Cardif by HCV-NS3/4A serine protease. Like NS3/4A, NS4B protein strongly blocks IFN-ß production signaling mediated by retinoic acid-inducible gene I (RIG-I); however, the underlying molecular mechanisms are not well understood. Recently, the stimulator of interferon genes (STING) was identified as an activator of RIG-I signaling. STING possesses a structural homology domain with flaviviral NS4B, which suggests a direct protein-protein interaction. In the present study, we investigated the molecular mechanisms by which NS4B targets RIG-I-induced and STING-mediated IFN-ß production signaling. IFN-ß promoter reporter assay showed that IFN-ß promoter activation induced by RIG-I or Cardif was significantly suppressed by both NS4B and NS3/4A, whereas STING-induced IFN-ß activation was suppressed by NS4B but not by NS3/4A, suggesting that NS4B had a distinct point of interaction. Immunostaining showed that STING colocalized with NS4B in the endoplasmic reticulum. Immunoprecipitation and bimolecular fluorescence complementation (BiFC) assays demonstrated that NS4B specifically bound STING. Intriguingly, NS4B expression blocked the protein interaction between STING and Cardif, which is required for robust IFN-ß activation. NS4B truncation assays showed that its N terminus, containing the STING homology domain, was necessary for the suppression of IFN-ß promoter activation. NS4B suppressed residual IFN-ß activation by an NS3/4A-cleaved Cardif (Cardif1-508), suggesting that NS3/4A and NS4B may cooperate in the blockade of IFN-ß production. CONCLUSION: NS4B suppresses RIG-I-mediated IFN-ß production signaling through a direct protein interaction with STING. Disruption of that interaction may restore cellular antiviral responses and may constitute a novel therapeutic strategy for the eradication of HCV.

Identification of novel N-(morpholine-4-carbonyloxy) amidine compounds as potent inhibitors against hepatitis C virus replication.

To identify novel compounds that possess antiviral activity against hepatitis C virus (HCV), we screened a library of small molecules with various amounts of structural diversity using an HCV replicon-expressing cell line and performed additional validations using the HCV-JFH1 infectious-virus cell culture. Of 4,004 chemical compounds, we identified 4 novel compounds that suppressed HCV replication with 50% effective concentrations of ranging from 0.36 to 4.81 µM. N'-(Morpholine-4-carbonyloxy)-2-(naphthalen-1-yl) acetimidamide (MCNA) was the most potent and also produced a small synergistic effect when used in combination with alpha interferon. Structure-activity relationship (SAR) analyses revealed 4 derivative compounds with antiviral activity. Further SAR analyses revealed that the N-(morpholine-4-carbonyloxy) amidine moiety was a key structural element for antiviral activity. Treatment of cells with MCNA activated nuclear factor κB and downstream gene expression. In conclusion, N-(morpholine-4-carbonyloxy) amidine and other related morpholine compounds specifically suppressed HCV replication and may have potential as novel chemotherapeutic agents.

Inhibitory effect of a triterpenoid compound, with or without alpha interferon, on hepatitis C virus infection.

A lack of patient response to alpha interferon (α-IFN) plus ribavirin (RBV) treatment is a major problem in eliminating hepatitis C virus (HCV). We screened chemical libraries for compounds that enhanced cellular responses to α-IFN and identified a triterpenoid, toosendanin (TSN). Here, we studied the effects and mechanisms of action of TSN on HCV replication and its effect on α-IFN signaling. We treated HCV genotype 1b replicon-expressing cells and HCV-J6/JFH-infected cells with TSN, with or without α-IFN, and the level of HCV replication was quantified. To study the effects of TSN on α-IFN signaling, we detected components of the interferon-stimulated gene factor 3 (ISGF3), phosphorylated signal transducer and activator of transcription 1 (STAT1), and STAT2 by Western blotting analysis; expression levels of mRNA of interferon regulatory factor 9 using real-time reverse transcription-PCR (RT-PCR); and interferon-stimulated response element reporter activity and measured the expression levels of interferon-inducible genes for 2',5'-oligoadenylate synthetase, MxA, protein kinase R, and p56 using real-time RT-PCR. TSN alone specifically inhibited expression of the HCV replicon (50% effective concentration = 20.6 nM, 50% cytotoxic concentration > 3 µM, selectivity index > 146). Pretreatment with TSN prior to α-IFN treatment was more effective in suppressing HCV replication than treatment with either drug alone. Although TSN alone did not activate the α-IFN pathway, it significantly enhanced the α-IFN-induced increase of phosphorylated STATs, interferon-stimulated response element activation, and interferon-stimulated gene expression. TSN significantly increased baseline expression of interferon regulatory factor 9, a component of interferon-stimulated gene factor 3. Antiviral effects of treatment with α-IFN can be enhanced by pretreatment with TSN. Its mechanisms of action could potentially be important to identify novel molecular targets to treat HCV infection.

Inhibition of hepatitis C virus replication by a specific inhibitor of serine-arginine-rich protein kinase.

Splicing of messenger RNAs is regulated by site-specific binding of members of the serine-arginine-rich (SR) protein family, and SR protein kinases (SRPK) 1 and 2 regulate overall activity of the SR proteins by phosphorylation of their RS domains. We have reported that specifically designed SRPK inhibitors suppressed effectively several DNA and RNA viruses in vitro and in vivo. Here, we show that an SRPK inhibitor, SRPIN340, suppressed in a dose-dependent fashion expression of a hepatitis C virus (HCV) subgenomic replicon and replication of the HCV-JFH1 clone in vitro. The inhibitory effects were not associated with antiproliferative or nonspecific cytotoxic effects on the host cells. Overexpression of SRPK1 or SRPK2 resulted in augmentation of HCV replication, while small interfering RNA (siRNA) knockdown of the SRPKs suppressed HCV replication significantly. Immunocytochemistry showed that SRPKs and the HCV core and NS5A proteins colocalized to some extent in the perinuclear area. Our results demonstrate that SRPKs are host factors essential for HCV replication and that functional inhibitors of these kinases may constitute a new class of antiviral agents against HCV infection.

Antiviral effects of the interferon-induced protein guanylate binding protein 1 and its interaction with the hepatitis C virus NS5B protein.

UNLABELLED: Interferons (IFNs) and the interferon-stimulated genes (ISGs) play a central role in antiviral responses against hepatitis C virus (HCV) infection. We have reported previously that ISGs, including guanylate binding protein 1 (GBP-1), interferon alpha inducible protein (IFI)-6-16, and IFI-27, inhibit HCV subgenomic replication. In this study we investigated the effects of these ISGs against HCV in cell culture and their direct molecular interaction with viral proteins. HCV replication and virus production were suppressed significantly by overexpression of GBP-1, IFI-6-16, or IFI-27. Knockdown of the individual ISGs enhanced HCV RNA replication markedly. A two-hybrid panel of molecular interaction of the ISGs with HCV proteins showed that GBP-1 bound HCV-NS5B directly. A protein truncation assay showed that the guanine binding domain of GBP-1 and the finger domain of NS5B were involved in the interaction. Binding of NS5B with GBP-1 inhibited its guanosine triphosphatase GTPase activity, which is essential for its antiviral effect. Taken together, interferon-induced GBP-1 showed antiviral activity against HCV replication. CONCLUSION: Binding of the HCV-NS5B protein to GBP-1 countered the antiviral effect by inhibition of its GTPase activity. These mechanisms may contribute to resistance to innate, IFN-mediated antiviral defense and to the clinical persistence of HCV infection.

Two flavonoids extracts from Glycyrrhizae radix inhibit in vitro hepatitis C virus replication.

AIM: Traditional herbal medicines have been used for several thousand years in China and other Asian countries. In this study we screened herbal drugs and their purified compounds, using the Feo replicon system, to determine their effects on in vitro HCV replication. METHODS: We screened herbal drugs and their purified extracts for the activities to suppress hepatitis C virus (HCV) replication using an HCV replicon system that expressed chimeric firefly luciferase reporter and neomycin phosphotransferase (Feo) genes. We tested extracts and 13 purified compounds from the following herbs: Glycyrrhizae radix; Rehmanniae radix; Paeoniae radix; Artemisiae capillari spica; and Rhei rhizoma. RESULTS: The HCV replication was significantly and dose-dependently suppressed by two purified compounds, isoliquiritigenin and glycycoumarin, which were from Glycyrrhizae radix. Dose-effect analyses showed that 50% effective concentrations were 6.2 +/- 1.0 microg/mL and 15.5 +/- 0.8 microg/mL for isoliquiritigenin and glycycoumarin, respectively. The MTS assay did not show any effect on cell growth and viability at these effective concentrations, indicating that the effects of the two compounds were specific to HCV replication. These two compounds did not affect the HCV IRES-dependent translation nor did they show synergistic action with interferon-alpha. CONCLUSION: Two purified herbal extracts, isoliquiritigenin and glycycoumarin, specifically suppressed in vitro HCV replication. Further elucidation of their mechanisms of action and evaluation of in vivo effects and safety might constitute a new anti-HCV therapeutics.

Serial measurement of Wisteria floribunda agglutinin positive Mac-2-binding protein is useful for predicting liver fibrosis and the development of hepatocellular carcinoma in chronic hepatitis C patients treated with IFN-based and IFN-free therapy.

AIM: Wisteria floribunda agglutinin positive (WFA+) Mac-2-binding protein (M2BPGi) is a noninvasive glyco-marker for liver fibrosis. This study evaluated the utility of serial measurement of serum M2BPGi and total M2BP as a predictor of fibrosis and the development of hepatocellular carcinoma (HCC). METHODS: This study included 119 patients with chronic hepatitis C (CHC). Of these patients, 97 were treated with IFN-based therapy and 22 were treated with daclatasvir and asunaprevir. Serum M2BPGi values were measured prior to, at the end of, and at 24 weeks after the completion of treatment. As subanalysis, serum total M2BP levels were measured in patients treated with pegylated-interferon and ribavirin. RESULTS: In patients treated with IFN-based therapy, M2BPGi levels were elevated at the end of treatment but decreased afterwards. In contrast, M2BPGi levels in patients treated with IFN-free therapy decreased immediately after starting the treatment without transient elevation. Though pre-treatment M2BPGi levels significantly correlated with fibrosis in both patients with a sustained virological response (SVR) and non-SVR, post-treatment M2BPGi levels decreased regardless of the degree of fibrosis in patients with SVR. In multivariate analysis, non-SVR and HCC development were independent factors associated with M2BPGi level ≥2.2. In patients treated with pegylated-interferon and ribavirin, total M2BP levels were positively correlated with fibrosis and HCC development. CONCLUSION: Real-time monitoring of the serum M2BPGi level after antiviral therapy for CHC patients could be a helpful screening tool for assessing the risk of HCC. M2BP and its glycan structure could be associated together with hepatocarcinogenesis.

Evaluation of Interferon Resistance in Newly Established Genotype 1b Hepatitis C Virus Cell Culture System.

BACKGROUND AND AIMS: The hepatitis C virus (HCV) genotype 1b is known to exhibit treatment resistance with respect to interferon (IFN) therapy. Substitution of amino acids 70 and 91 in the core region of the 1b genotype is a significant predictor of liver carcinogenesis and poor response to pegylated-IFN-α and ribavirin therapy. However, the molecular mechanism has not yet been clearly elucidated because of limitations of the HCV genotype 1b infectious model. Recently, the TPF1-M170T HCV genotype 1b cell culture system was established, in which the clone successfully replicates and infects Huh-7-derived Huh7-ALS32.50 cells. Therefore, the purpose of this study was to compare IFN resistance in various HCV clones using this system. METHODS: HCV core amino acid substitutions R70Q and L91M were introduced to the TPF1-M170T clone and then transfected into Huh7-ALS32.50 cells. To evaluate the production of each virus, intracellular HCV core antigens were measured. RESULTS were confirmed with Western blot analysis using anti-NS5A antibodies, and IFN sensitivity was subsequently measured. RESULTS: Each clone was transfected successfully compared with JFH-1, with a significant difference in intracellular HCV core antigen (p < 0.05), an indicator of continuous HCV replication. Among all clones, L91M showed the highest increase in the HCV core antigen and HCV protein. There was no significant resistance against IFN treatment in core substitutions; however, IFN sensitivity was significantly different between the wildtype core and JFH-1 (p < 0.05). CONCLUSIONS: A novel genotype 1b HCV cell culture was constructed with core amino acid substitutions, which demonstrated IFN resistance of genotype 1b. This system will be useful for future analyses into the mechanisms of HCV genotype 1b treatment.

Comprehensive analyses of mutations and hepatitis B virus integration in hepatocellular carcinoma with clinicopathological features.

BACKGROUND AND AIMS: Genetic alterations in specific genes are critical events in carcinogenesis and hepatocellular carcinoma (HCC) progression. However, the genetic alterations responsible for HCC development, progression, and survival are unclear. METHODS: We investigated the essential difference in genetic alterations between HCC and adjacent non-HCC tissues using next-generation sequencing technology. RESULTS: We found recurrent mutations in several genes such as telomerase reverse transcriptase (TERT; 65% of the total 104 HCCs), TP53 (38%), CTNNB1 (30%), AXIN1 (2%), PTEN (2%), and CDKN2A (2%). TERT promoter mutations were associated with older age (p = 0.005), presence of hepatitis C virus (HCV) infection (p = 0.003), and absence of hepatitis B virus (HBV) infection (p < 0.0001). In hepatitis B surface antigen (HBs Ag)-positive HCC without TERT promoter mutations, HBV integration into TERT locus was found in 47% patients and was mutually exclusive to TERT promoter mutations. Most (89%) HBV integrants were in the HBx region. TP53 mutations were associated with HBV infection (p = 0.0001) and absence of HCV infection (p = 0.002). CTNNB1 mutations were associated with absence of HBV infection (p = 0.010). Moreover, TERT promoter mutation was significantly associated with shorter disease-free survival (p = 0.005) and poor overall survival (p = 0.024). CONCLUSIONS: Gene alterations in TERT promoter, TP53, CTNNB1, and HBV integration were closely associated with HCC development, and mutations in TERT promoter are related to poor prognosis. These results are useful for understanding the underlying mechanism of hepatocarcinogenesis, diagnosis, and predicting outcomes of patients with HCC.

Primary hepatic neuroendocrine carcinoma with a cholangiocellular carcinoma component in one nodule.

Primary neuroendocrine carcinomas (NECs) in the liver are very rare; however, several reports have described cases of a primary hepatic NEC combined with a hepatocellular carcinoma (HCC). We present the first report of a primary hepatic NEC with a cholangiocellular carcinoma (CCC) component in one nodule in a patient with a metachronous liver HCC. A 73-year old man who had received partial hepatectomy surgery because of a primary HCC and a primary CCC two years prior was diagnosed with a primary hepatic NEC after surgical treatment. Histological analysis of the resected tumor revealed that the tumor consisted of a predominant NEC area with a partial CCC component in one nodule and that the NEC cells were negative for markers of pancreatic NEC. Neoplastic cells in both the NEC and CCC component focally expressed CD44, a representative marker for cancer-initiating cells, and the CD44-positive cells in the NEC component were seen in the vicinity of those in the CCC component of one nodule. This case report provides suggestive information for the origin of primary hepatic NECs.

Association of ITPA gene variation and serum ribavirin concentration with a decline in blood cell concentrations during pegylated interferon-alpha plus ribavirin therapy for chronic hepatitis C.

BACKGROUND: Genetic variation leading to inosine triphosphatase (ITPA) deficiency protects chronic hepatitis C patients receiving ribavirin against hemolytic anemia. The relationship between ITPA gene variation and serum ribavirin concentration was analyzed in association with a reduction in blood cells and dose reduction of pegylated interferon (PEG-IFN) or ribavirin. PATIENTS AND METHODS: A total of 300 hepatitis C patients treated with PEG-IFN plus ribavirin were analyzed. Genetic polymorphisms were determined in ITPA and the quantitative reduction in blood cells from the baseline was analyzed every 4 weeks for the duration of treatment and after the end of therapy. The decline in hemoglobin (Hb) or platelet (PLT) level at week 4 compared to baseline was also assessed according to ribavirin concentrations. RESULTS: Patients with the ITPA-CA/AA genotypes showed a lower degree of Hb reduction throughout therapy than those with the ITPA-CC genotype and a marked difference in mean Hb reduction was found at week 4 (CA/AA -1.0 vs. CC -2.8, p < 0.001). The ITPA-CC genotype had significantly less reduction in the mean platelet count than the ITPA-CA/AA genotypes early during treatment (p < 0.001 for weeks 4 and 8). Patients with the ITPA-CA/AA genotypes were less likely to develop anemia, regardless of the concentration of ribavirin. Patients with baseline PLT counts below 130 × 10(3)/µl had a significantly lower tendency to achieve sustained virological response (SVR), especially those with the ITPA-CA/AA genotypes. ITPA gene variation was not extracted by multivariable analysis as an important predictor of SVR. CONCLUSIONS: Despite the fact that ITPA variants were less likely to develop anemia, patients with low baseline PLT counts were difficult to treat, especially those with the ITPA-CA/AA genotype. These results may give a valuable pharmacogenetic diagnostic tool for the tailoring of dosing to minimize drug-induced adverse events.

Studies on virus kinetics using infectious fluorescence-tagged hepatitis C virus cell culture.

AIM: Studies of the complete hepatitis C virus (HCV) life cycle have become possible with the development of a HCV-JFH1 cell culture system. METHODS: In this study, we constructed two fluorescence protein-tagged recombinant JFH1 virus clones, JFH1-EYFP and JFH1-AsRed, as well as two corresponding clones with adaptive mutations, JFH1-EYFP mutant and JFH1-AsRed mutant, that and were as effective as JFH1 in producing infectious virus particles, and investigated their viral infection life cycles. RESULTS: After infection of the fluorescence-tagged mutant viruses, infected cells increased exponentially. In cells, EYFP or AsRed and NS5A were expressed as a fusion protein and co-localized in core proteins. The rate of the cell-cell spread was dependent on the cell densities with a maximum of 10(2.5) /day. Treatment of cells with interferon or a protease inhibitor suppressed expansion of virus-positive cells. CONCLUSION: Taken together, these results indicate that fluorescence-tagged HCV is a useful tool to study virus infection life cycles and to assist in the search for novel antiviral compounds.

Serum interleukin-6 levels correlate with resistance to treatment of chronic hepatitis C infection with pegylated-interferon-α2b plus ribavirin.

BACKGROUND: Interleukin (IL)-6, a pleiotropic cytokine, is increased in various types of chronic liver disease, including chronic hepatitis C (CHC). It was reported recently that IL-6 is associated with insulin resistance, iron metabolism and interferon resistance, which may affect the outcome of antiviral treatment. In this study, we investigated the association of serum IL-6 levels with outcomes of pegylated interferon (PEG-IFN) plus ribavirin (RBV) combination therapy. METHODS: We included 149 CHC patients and measured serum IL-6 levels at baseline and at 4, 8 and 12 weeks, and the end of treatment in 49 patients. We performed univariate and multivariate regression analyses for the association of IL-6 levels and clinical and laboratory parameters and treatment responses. RESULTS: Serum IL-6 levels were significantly higher in CHC patients than healthy subjects. Pretreatment IL-6 levels of male patients were inversely correlated with sustained virological response (SVR) in univariate analysis (P=0.012). In male patients with SVR, serum IL-6 levels decreased significantly at 4 weeks of treatment (P=0.029) and remained significantly lower than those of non-SVR patients after 4, 8 and 12 weeks of PEG-IFN plus RBV therapy. CONCLUSIONS: Our results suggest that baseline levels of IL-6, as well as their decrease during treatment, are correlated to outcomes of PEG-IFN plus RBV therapy in male patients. Further analyses of IL-6 may provide new strategies for difficult-to-treat CHC patients and prevention of hepatocarcinogenesis.

ITPA gene variant protects against anemia induced by pegylated interferon-α and ribavirin therapy for Japanese patients with chronic hepatitis C.

AIM: Host genetic variants leading to inosine triphosphatase (ITPA) deficiency, a condition not thought to be clinically important, protect against hemolytic anemia in chronic hepatitis C patients receiving ribavirin. In this study, we evaluated the clinical significance of ITPA variants in Japanese hepatitis C patients who were treated with pegylated interferon plus ribavirin. METHODS: In this multicenter retrospective cross-sectional study, 474 hepatitis C patients were enrolled who were treated with pegylated interferon plus ribavirin in four geographically different hospitals in Japan. Patients were grouped according to hemoglobin decline of more than 3 g/dL at week 4. Two single nucleotide polymorphisms (SNP) within or adjacent to the ITPA gene (rs6051702, rs1127354) were genotyped. RESULTS: A functional SNP, rs1127354, within the ITPA exon was strongly associated with protection against anemia with only one (0.8%) in 129 patients with the ITPA minor variant A developing severe anemia (P=5.9×10(-20) ). For rs6051702, which had significant association in European-Americans, significant but weak association with severe hemoglobin reduction was found in Japanese (P= 0.009). In patients excluding genotype 1b and high viral load, those with the ITPA minor variant A achieved significantly higher sustained viral response rate than those with the major variant (CC) (96% vs 70%, respectively, P= 0.0066). CONCLUSION: ITPA SNP, rs1127354, is confirmed to be a useful predictor of ribavirin-induced anemia in Japanese patients. Patients with the ITPA minor variant A (~ 27%) have an advantage in pegylated interferon plus ribavirin-based therapies, due to expected adherence of ribavirin doses, resulting in a higher viral clearance rate.

Comparison of HCV-associated gene expression and cell signaling pathways in cells with or without HCV replicon and in replicon-cured cells.

BACKGROUND: Hepatitis C virus (HCV) replication is affected by several host factors. Here, we screened host genes and molecular pathways that are involved in HCV replication by comprehensive analyses using two genotypes of HCV replicon-expressing cells, their cured cells and naïve Huh7 cells. METHODS: Huh7 cell lines that stably expressed HCV genotype 1b or 2a replicon were used. The cured cells were established by treating HCV replicon cells with interferon-alpha. Expression of 54,675 cellular genes was analyzed by GeneChip DNA microarray. The data were analyzed by using the KEGG Pathway database. RESULTS: Hierarchical clustering analysis showed that the gene-expression profiles of each cell group constituted clear clusters of naïve, HCV replicon-expressed, and cured cell lines. The pathway process analysis between the replicon-expressing and the cured cell lines identified significantly altered pathways, including MAPK, steroid biosynthesis and TGF-beta signaling pathways, suggesting that these pathways were affected directly by HCV replication. Comparison of cured and naïve Huh7 cells identified pathways, including steroid biosynthesis and sphingolipid metabolism, suggesting that these pathways were required for efficient HCV replication. Cytoplasmic lipid droplets were obviously increased in replicon-expressing and cured cells as compared to naïve cells. HCV replication was significantly suppressed by peroxisome proliferator-activated receptor (PPAR)-alpha agonists but augmented by PPAR-gamma agonists. CONCLUSION: Comprehensive gene expression and pathway analyses show that lipid biosynthesis pathways are crucial to support proficient virus replication. These metabolic pathways could constitute novel antiviral targets against HCV.

Development of plaque assays for hepatitis C virus-JFH1 strain and isolation of mutants with enhanced cytopathogenicity and replication capacity.

HCV culture in vitro results in massive cell death, which suggests the presence of HCV-induced cytopathic effects. Therefore, we investigated its mechanisms and viral nucleotide sequences involved in this effect using HCV-JFH1 cell culture and a newly developed HCV plaque assay technique. The plaque assay developed cytopathic plaques, depending on the titer of the inoculum. In the virus-infected cells, the ER stress markers, GRP78 and phosphorylated eIF2-alpha, were overexpressed. Cells in the plaques were strongly positive for an apoptosis marker, annexin V. Isolated virus subclones from individual plaque showed greater replication efficiency and cytopathogenicity than the parental virus. The plaque-purified virus had 9 amino acid substitutions, of which 5 were clustered in the C terminal of the NS5B region. Taken together, the cytopathic effect of HCV infection involves ER-stress-induced apoptotic cell death. Certain HCV genomic structures may determine the viral replication capacity and cytopathogenicity.

Hepatitis C virus non-structural proteins responsible for suppression of the RIG-I/Cardif-induced interferon response.

Viral infections activate cellular expression of type I interferons (IFNs). These responses are partly triggered by RIG-I and mediated by Cardif, TBK1, IKKepsilon and IRF-3. This study analysed the mechanisms of dsRNA-induced IFN responses in various cell lines that supported subgenomic hepatitis C virus (HCV) replication. Transfection of dsRNA into Huh7, HeLa and HEK293 cells induced an IFN expression response as shown by IRF-3 dimerization, whilst these responses were abolished in corresponding cell lines that expressed HCV replicons. Similarly, RIG-I-dependent activation of the IFN-stimulated response element (ISRE) was significantly suppressed by cells expressing the HCV replicon and restored in replicon-eliminated cells. Overexpression analyses of individual HCV non-structural proteins revealed that NS4B, as well as NS34A, significantly inhibited RIG-I-triggered ISRE activation. Taken together, HCV replication and protein expression substantially blocked the dsRNA-triggered, RIG-I-mediated IFN expression response and this blockade was partly mediated by HCV NS4B, as well as NS34A. These mechanisms may contribute to the clinical persistence of HCV infection and could constitute a novel antiviral therapeutic target.