Hepatitis C virus (HCV) causes a persistent infection, chronic hepatitis and hepatocellular carcinoma. HCV NS5A, one of non-structural proteins of HCV, was suggested to play a role in oncogenic transformation. Since the tumor suppressor p53 is important for preventing neoplastic transformation, we investigated the functional effects of HCV NS5A on p53. In vitro and in vivo coimmunoprecipitation and confocal microscopy were used to determine the interaction of NS5A and p53. HCV NS5A binds directly to p53 and colocalizes p53 in the perinuclear region. NS5A inhibits transcriptional transactivation by p53 in a dose-dependent manner by use of a reporter assay. Down regulation of endogenous p21/waf1 expression, which is activated by p53 in Hep3B cells, by NS5A was demonstrated by using FLAG-and FLAG-NS5A Hep3B stable cell lines. The effect of NS5A on p53-mediated apoptosis was determined by flow cytometry in both NS5A permanently and transiently transfected Hep3B cells with exogenous p53. The p53-induced apoptosis was abrogated by NS5A and the inhibition effect correlates well with the binding ability of NS5A to p53. In addition, HCV NS5A protein interacts with and colocalizes hTAF II 32, a component of TFIID and an essential coactivator of p53, in vivo. These results suggest that HCV NS5A interacts with and partially sequestrates p53 and hTAF II 32 in the cytoplasm and suppresses p53-mediated transcriptional transactivation and apoptosis during HCV infection, which may contribute to the hepatocarcinogenesis of HCV infection.

Hepatitis C virus (HCV) causes a persistent infection, chronic hepatitis, and hepatocellular carcinoma. Since there are several reports indicating that some viruses influence the tumor suppressor p53 function, we determined the effects of HCV proteins on p53 function and its mechanism determined by use of a reporter assay. Among seven HCV proteins investigated (core, NS2, NS3, NS4A, NS4B, NS5A, and NS5B), only core protein augmented the transcriptional activity of p53 and increased the expression of p21(waf1) protein, which is a major target of p53. Core protein increased both DNA-binding affinity of p53 in electrophoretic morbidity shift assay and transcriptional ability of p53 itself in a reporter assay. The direct interaction between core protein and C terminus of p53 was also shown by glutathione S-transferase fusion protein binding assay. In addition, core protein interacted with hTAF(II)28, a component of the transcriptional factor complex in vivo and in vitro. These results suggest that HCV core protein interacts with p53 and modulates p53-dependent promoter activities during HCV infection.

To clarify the effects of hepatitis C virus (HCV) infection on hepatocytes, we analyzed and compared the induction of intracellular signals by HCV and hepatitis B virus (HBV) proteins. We examined the influence of 7 HCV (core, NS2, NS3, NS4A, NS4B, NS5A, and NS5B) and 4 HBV (precore, core, polymerase, and X) proteins on 5 well-defined intracellular signaling pathways associated with cell proliferation, differentiation, and apoptosis by use of a reporter assay. Viral protein-expression vectors were cotransfected into mammalian cells with reporter vectors having a luciferase gene driven by the following inducible cis-enhancer elements: the cyclic adenosine monophosphate response element, the serum response element (SRE), and the binding sites for nuclear factor kappaB (NF-kappaB), activator protein 1 (AP-1), and serum response factor (SRF). In addition, the activation of signals by HCV proteins was examined in a reporter plasmid having a natural interleukin-8 (IL-8) promoter upstream of a luciferase gene. Of 11 HCV and HBV proteins, HCV core had the strongest influence on intracellular signals, especially NF-kappaB-, AP-1-, and SRE-associated pathways. HCV core's activation level exceeded that of HBV X protein, a well-characterized transactivator of these signals. Moreover, HCV core activated the IL-8 promoter through NF-kappaB and AP-1. For the other proteins, HCV NS4B showed signal activation, but signals were activated at a lesser extent. The luciferase reporter assay, a recently introduced technique, helped in the elucidation of molecular events underlying the inflammatory and proliferation process in the liver induced by HCV.

Hepatitis B virus (HBV) infection is a major health problem, with 1.2 million deaths per year worldwide according to the 1997 World Health Organization report. 1 It causes acute and chronic liver diseases, including life-threatening fulminant hepatitis, cirrhosis, and hepatocellular carcinoma. 2 Despite the existence of an effective vaccine, no effective antiviral treatment has been developed for the patients chronically infected with HBV. Although interferon therapy benefits some patients with chronic hepatitis B, the overall response rate is less than 40% and interferon has doselimiting side-effects. 3,4 Because the replication of HBV DNA proceeds through reverse transcription of a pregenomic RNA intermediate, 5 the use of reverse-transcriptase inhibitors as an antiviral drug for hepatitis B has become an attractive option. Lamivudine, or (-)-␤-L-2Ј,3Ј-dideoxy-3Ј-thiacytidine (3TC), is one many of reverse-transcriptase inhibitors and has antiviral activity against human immunodeficiency virus (HIV) 6 and HBV. [7][8][9][10][11][12][13] Recently, lamivudine was used to treat patients with chronic hepatitis B and reduced HBV DNA to an undetectable level, with few adverse effects. 8 Lamivudine also proved useful in preventing HBV reinfection of the graft after liver transplantation. [11][12][13] However, recent studies reported the emergence of lamivudine-resistant HBV during treatment. 14-17 Lamivudine-resistant HBV was revealed to have methionine (M) to isoleusine (I) or valine (V) substitutions in the tyrosine (Y), methionine (M), aspartate (D), aspartate (D) motif (YMDD motif) of the RNA-dependent DNA polymerase, as was seen in lamivudine-resistant HIV. The YMDD motif is one of the highly conserved domains in RNAdependent DNA polymerase present in retroviruses, hepadnaviruses, retrotransposons, group II intron, bacterial retrons, and the catalytic subunit of telomerase, and is involved in nucleotide binding in the catalytic site of the polymerase. [18][19][20][21][22][23] Amino acid substitutions in this motif were also associated with the resistance of HIV to other nucleoside analogues, such as ddC and FTC (5-fluoro-derivative of lamivudine). 21 Emergence of resistant viruses to nucleoside analogues has stimulated a heightened interest in the study of the YMDD motif, and more appropriate knowledge of HBV drugresistance patterns to lamivudine is considered imperative in improving patient management. The present study was designed to evaluate replication competence and the susceptibility to lamivudine of the YMDD motif variants of HBV in human hepatoma cells transiently transfected by full-length HBV DNA.

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Immune checkpoint inhibitors (ICIs) with nivolumab and pembrolizumab are promising agents for advanced hepatocellular carcinoma (HCC) but lack of effective biomarkers. We aimed to investigate the potential predictors of response and factors associated with overall survival (OS) for ICI treatment in unresectable HCC patients. Ninety-five patients who received nivolumab or pembrolizumab for unresectable HCC were enrolled for analyses. Radiologic evaluation was based on RECIST v1.1. Factors associated with outcomes were analyzed. Of 90 patients with evaluable images, the objective response rate (ORR) was 24.4%. Patients at Child–Pugh A or received combination treatment had higher ORR. Early alpha-fetoprotein (AFP) >10% reduction (within 4 weeks) was the only independent predictor of best objective response (odds ratio: 7.259, p = 0.001). For patients with baseline AFP ≥10 ng/mL, significantly higher ORR (63.6% vs. 10.2%, p < 0.001) and disease control rate (81.8% vs. 14.3%, p < 0.001) were observed in those with early AFP reduction than those without. In addition, early AFP reduction and albumin-bilirubin (ALBI) grade or Child–Pugh class were independent factors associated with OS in different models. In conclusion, a 10-10 rule of early AFP response can predict objective response and survival to ICI treatment in unresectable HCC. ALBI grade and Child–Pugh class determines survival by ICI treatment.

BackgroundImmunotherapy with immune checkpoint inhibitor (ICI) is a promising treatment for unresectable hepatocellular carcinoma (HCC). However, whether ICIs would have the risk of hepatitis B virus (HBV) reactivation and the necessary of nucleos(t)ide analogs (NUCs) prophylaxis are still unclear. We aimed to investigate the role of NUCs prophylaxis in HBV-infected patients who underwent ICIs treatment.MethodsThe study was a retrospective prospective design to review and follow-up consecutive 62 patients with chronic hepatitis B or resolved HBV infection who had received ICIs treatment for the unresectable HCC. Of them, 60 patients with documented baseline serum HBV DNA value were classified into three categories according to the baseline HBV viral load and the status of antiviral therapy before ICI treatment. The clinical status, including tumor response, viral kinetics and liver function, was recorded and investigated.ResultsNo HBV reactivation occurred in the 35 patients with HBV DNA ≤100 IU/mL on NUCs therapy. Of the 19 patients with HBV DNA >100 IU/mL who started NUCs simultaneously with ICI treatment, none encountered HBV reactivation during the immunotherapy. Of the six HBV patients without NUCs treatment, three had a greater than 1 log decrease in HBV viral load, and one maintained his serum HBV DNA in undetectable status during ICI treatment. Eventually, one out of six experienced HBV reactivation after 9 weeks of ICI treatment.ConclusionNo patients on antiviral therapy developed HBV reactivation, and one out of six not receiving antiviral therapy had HBV reactivation. HBV viral load higher than 100 IU/mL is safe and not a contraindication for ICI treatment for HCC, if NUCs can be coadministrated.