Approximately 350 million people are estimated to be persistently infected with hepatitis B virus(HBV) worldwide. HBV maintains persistent infection by employing covalently closed circular DNA(ccc ...DNA), a template for all HBV RNAs. Chronic hepatitis B(CHB) patients are currently treated with nucleos(t)ide analogs such as lamivudine, adefovir, entecavir, and tenofovir. However, these treatments rarely cure CHB because they are unable to inhibit ccc DNA transcription and inhibit only a late stage in the HBV life cycle(the reverse transcription step in the nucleocapsid). Therefore, an understanding of the factors regulating ccc DNA transcription is required to stop this process. Among numerous factors, hepatocyte nuclear factors(HNFs) play the most important roles in ccc DNA transcription, especially in the generation of viral genomic RNA, a template for HBV replication. Therefore, proper control of HNF function could lead to the inhibition of HBV replication. In this review, we summarize and discuss the current understanding of the roles of HNFs in the HBV life cycle and the upstream factors that regulate HNFs. This knowledge will enable the identification of new therapeutic targets to cure CHB.
Tumor necrosis factor superfamily (TNFSF) resistance contributes to the development and progression of tumors and resistance to various cancer therapies. Tumor-intrinsic alterations involved in the ...adaptation to the TNFSF response remain largely unknown. Here, we demonstrate that protein kinase C substrate 80K-H (PRKCSH) abundance in lung cancers boosts oncogenic IGF1R activation, leading to TNFSF resistance. PRKCSH abundance is correlated with IGF1R upregulation in lung cancer tissues. Specifically, PRKCSH interacts with IGF1R and extends its half-life. The PRKCSH-IGF1R axis in tumor cells impairs caspase-8 activation, increases Mcl-1 expression, and inhibits caspase-9, leading to an imbalance between cell death and survival. PRKCSH deficiency augmented the antitumor effects of natural killer (NK) cells, representative TNFSF effector cells, in a tumor xenograft IL-2Rg-deficient NOD/SCID (NIG) mouse model. Our data suggest that PRKCSH plays a critical role in TNFSF resistance and may be a potential target to improve the efficacy of NK cell-based cancer therapy.
Background and Aim
Interferon‐stimulated gene 20 (ISG20) is an interferon‐inducible exonuclease that inhibits the replication of several RNA viruses. In patients with chronic hepatitis B, ISG20 ...expression is related to the interferon‐α treatment response. However, the molecular mechanism of ISG20‐mediated anti‐hepatitis B virus (HBV) activity is unclear.
Methods
We have investigated the effect of ISG20 on antiviral activity to address that. The life cycle of HBV was analyzed by the ectopic expression of ISG20 in HepG2 and HepG2‐NTCP cells. Finally, to provide physiological relevance of our study, the expression of ISG20 from chronic hepatitis B patients was examined.
Results
Interferon‐stimulated gene 20 was mainly induced by interferon‐β and dramatically inhibited HBV replication. In addition, ISG20 decreased HBV gene expression and transcription. Although ISG20 inhibited HBV replication by reducing viral enhancer activity, the expression of transcription factors that bind the HBV enhancer was not affected. Particularly, ISG20 suppressed HBV enhancer activity by binding to the enhancer II and core promoter (EnhII/Cp) region.
Conclusion
Our findings suggest that ISG20 exerts the anti‐HBV activity by acting as a putative repressor binding to the HBV EnhII/Cp region.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The multifunctional influenza virus protein PB1‐F2 plays several roles in deregulation of host innate immune responses and is a known immunopathology enhancer of the 1918 influenza pandemic. Here, we ...show that the 1918 PB1‐F2 protein not only interferes with the mitochondria‐dependent pathway of type I interferon (IFN) signaling, but also acquired a novel IFN antagonist function by targeting the DEAD‐box helicase DDX3, a key downstream mediator in antiviral interferon signaling, toward proteasome‐dependent degradation. Interactome analysis revealed that 1918 PB1‐F2, but not PR8 PB1‐F2, binds to DDX3 and causes its co‐degradation. Consistent with intrinsic protein instability as basis for this gain‐of‐function, internal structural disorder is associated with the unique cytotoxic sequences of the 1918 PB1‐F2 protein. Infusing mice with recombinant DDX3 protein completely rescued them from lethal infection with the 1918 PB1‐F2‐producing virus. Alongside NS1 protein, 1918 PB1‐F2 therefore constitutes a potent IFN antagonist causative for the severe pathogenicity of the 1918 influenza strain. Our identification of molecular determinants of pathogenesis should be useful for the future design of new antiviral strategies against influenza pandemics.
Synopsis
The comparative interactome analysis revealed that 1918 PB1‐F2 hijacks a key mediator of IFN signaling, DDX3, leading to its proteasomal degradation, and thus shuts off the antiviral response.
Influenza PB1‐F2 protein plays a multi‐functional role in deregulation of innate immune responses and is known to enhance the immunopathology in 1918 pandemic virus.
We have showed through the interactome analysis that, DDX3, an essential host protein in the type I IFN signaling pathway, binds to and is co‐degraded with 1918 PB1‐F2.
The hijacking of a key mediator of IFN signaling uncouples the host antiviral responses from the viral infection, resulting in enhanced virulence.
Our study reveals a novel molecular basis for the severe pathogenicity of the 1918 strain which will be useful for designing new therapeutic options against influenza pandemics.
Comparative interactome analysis reveals a new mechanism for antagonizing interferon responses by the pandemic 1918 influenza strain, through proteasomal degradation of an antiviral innate immunity mediator.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Background and Aim
Besifovir dipivoxil maleate (BSV) was reported to have comparable antiviral efficacy and superior renal and bone safety to tenofovir disoproxil fumarate (TDF) in chronic hepatitis ...B (CHB) patients. The present study aims to evaluate changes of liver histology and intrahepatic covalently closed circular DNA (cccDNA) levels by BSV treatment in comparison with TDF therapy.
Methods
This is a subset study of the phase 3 trial comparing BSV with TDF. Among them, only CHB patients willing to participate in a histologic evaluation study were enrolled. Liver histologic examination and intrahepatic cccDNA quantification were performed.
Results
A total of 46 CHB patients received liver biopsies (BSV, n = 29; TDF, n = 17). After 48 weeks of treatment, virological response rate was comparable between the groups (P = 0.707). Follow‐up liver biopsies showed that necroinflammation was significantly improved in the both groups. However, the histological response rate defined as the proportion of subjects whose modified histologic activity index score decreased by ≥ 2 without deterioration in fibrosis was higher in the BSV group than in the TDF group (77.8% vs 36.4%, P = 0.048). The proportion of subjects with Ishak fibrosis score 3 or more decreased from 77.7% to 55.5% in the BSV and that decreased from 72.7% to 45.4% in the TDF group. The intrahepatic cccDNA significantly decreased from baseline after 48 weeks of BSV or TDF treatment (P < 0.001) without intergroup differences (P = 0.349).
Conclusions
The BSV therapy improves hepatic histology and decreases intrahepatic cccDNA in CHB patients.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Cytokines are involved in early host defense against pathogen infections. In particular, tumor necrosis factor (TNF) and interferon-gamma (IFN-γ) have critical functions in non-cytopathic elimination ...of hepatitis B virus (HBV) in hepatocytes. However, the molecular mechanisms and mediator molecules are largely unknown. Here we show that interleukin-32 (IL-32) is induced by TNF and IFN-γ in hepatocytes, and inhibits the replication of HBV by acting intracellularly to suppress HBV transcription and replication. The gamma isoform of IL-32 (IL-32γ) inhibits viral enhancer activities by downregulating liver-enriched transcription factors. Our data are validated in both an in vivo HBV mouse model and primary human hepatocytes. This study thus suggests that IL-32γ functions as intracellular effector in hepatocytes for suppressing HBV replication to implicate a possible mechanism of non-cytopathic viral clearance.
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•Among oral antivirals for HBV infection, only tenofovir has revealed no genotypically resistant HBV.•However, there are patients with incomplete viral response during ...tenofovir-containing treatment.•We consistently identified 7 common mutations including rtS106C (C), rtH126Y (Y), rtD134E (E), and rtL269I (I).•The mutations C, Y, and E were novel mutations associated with drug resistance.•The quadruple CYEI mutation increases the amount of tenofovir required to inhibit HBV by 15.3-fold in IC50 and 26.3-fold in IC90.•All tenofovir-resistant mutants with/without entecavir resistance were susceptible to a novel capsid assembly modulator.
Tenofovir disoproxil fumarate (TDF) is one the most potent nucleot(s)ide analogues for treating chronic hepatitis B virus (HBV) infection. Phenotypic resistance caused by genotypic resistance to TDF has not been reported. This study aimed to characterize HBV mutations that confer tenofovir resistance.
Two patients with viral breakthrough during treatment with TDF-containing regimens were prospectively enrolled. The gene encoding HBV reverse transcriptase was sequenced. Eleven HBV clones harboring a series of mutations in the reverse transcriptase gene were constructed by site-directed mutagenesis. Drug susceptibility of each clone was determined by Southern blot analysis and real-time PCR. The relative frequency of mutants was evaluated by ultra-deep sequencing and clonal analysis.
Five mutations (rtS106C C, rtH126Y Y, rtD134E E, rtM204I/V, and rtL269I I) were commonly found in viral isolates from 2 patients. The novel mutations C, Y, and E were associated with drug resistance. In assays for drug susceptibility, the IC50 value for wild-type HBV was 3.8 ± 0.6 µM, whereas the IC50 values for CYE and CYEI mutants were 14.1 ± 1.8 and 58.1 ± 0.9 µM, respectively. The IC90 value for wild-type HBV was 30 ± 0.5 µM, whereas the IC90 values for CYE and CYEI mutants were 185 ± 0.5 and 790 ± 0.2 µM, respectively. Both tenofovir-resistant mutants and wild-type HBV had similar susceptibility to the capsid assembly modulator NVR 3–778 (IC50 <0.4 µM vs. IC50 = 0.4 µM, respectively).
Our study reveals that the quadruple (CYEI) mutation increases the amount of tenofovir required to inhibit HBV by 15.3-fold in IC50 and 26.3-fold in IC90. These results demonstrate that tenofovir-resistant HBV mutants can emerge, although the genetic barrier is high.
Tenofovir is the most potent nucleotide analogue for the treatment of chronic hepatitis B virus infection and there has been no hepatitis B virus mutation that confers >10-fold resistance to tenofovir up to 8 years. Herein, we identified, for the first time, a quadruple mutation that conferred 15.3-fold (IC50) and 26.3-fold (IC90) resistance to tenofovir in 2 patients who experienced viral breakthrough during tenofovir treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abbreviations SARS-CoV-2 severe acute respiratory syndrome coronavirus 2 TLR toll-like receptor NSCLC non-small cell lung cancer ACE2 angiotensin-converting enzyme 2 TMPRSS2 transmembrane protease ...serine subtype 2 GSEA gene set enrichment analysis Pam3CSK4 tripalmitoyl-S-glycero-Cys-(Lys) 4 FSL-1 fibroblast stimulating lipopeptide 1 NF-κB nuclear factor kappa-light-chain-enhancer of activated B cells IKK inhibitor of nuclear factor-κB kinase ERK extracellular signal-regulated kinase CRISPR-Cas9 clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9 Dear editor, Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can lead to severe outcomes in patients with cancer 1. Abbreviations: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TLR, toll-like receptor; NSCLC, non-small cell lung cancer; ∆Mag; magnitude difference; ACE2, angiotensin-converting enzyme 2; TMPRSS2, transmembrane protease serine subtype 2; LTTs, lung tumor tissues; mLNTs, matched lung normal tissues; GSEA, gene set enrichment analysis; IL-1R, interleukin-1 receptor; TNF, tumor necrosis factor; Pam3CSK4, tripalmitoyl-S-glycero-Cys-(Lys) 4; FSL-1, fibroblast stimulating lipopeptide 1; TLR2-KO, TLR2-knockout; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; ELISA, enzyme-linked immunosorbent assay; IKK, inhibitor of nuclear factor-κB kinase; ERK, extracellular signal-regulated kinase; CRISPR-Cas9, clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9; IL-6, interleukin 6. SARS-CoV-2 virus can infect human cells and induce inflammatory cytokines and chemokines, including IL-6, IL-1β, TNF-α, C-X-C motif chemokine ligand 1 (CXCL1), CXCL2, and C-C motif chemokine ligand 2 (CCL2), via TLR2-dependent activation of the NF-κB pathway 3–6. ...we further assessed whether expression levels of ACE2, TMPRSS2, TLR1, TLR2, and TLR6 were associated with gene sets related to inflammatory cytokines and chemokines. Upon treatment with the SARS-CoV-2 S protein, Pam3CSK4 (an agonist of TLR1/2), or FSL-1 (an agonist of TLR2/6), migration and invasion abilities of A549 and H1299 lung cancer cells were significantly enhanced compared to those upon treatment with vehicle control (Figure 1G-H, Supplementary Figure S6). ...colony-forming and cell proliferation assay revealed significant increases in response to the SARS-CoV-2 S protein, Pam3CSK4, or FSL-1 (Supplementary Figure S7).
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Unfolded protein response (UPR) is an adaptive mechanism that aims at restoring ER homeostasis under severe environmental stress. Malignant cells are resistant to environmental stress, which is ...largely due to an activated UPR. However, the molecular mechanisms by which different UPR branches are selectively controlled in tumor cells are not clearly understood. Here, we provide evidence that PRKCSH, previously known as glucosidase II beta subunit, functions as a regulator for selective activation of the IRE1α branch of UPR. PRKCSH boosts ER stress-mediated autophosphorylation and oligomerization of IRE1α through mutual interaction. PRKCSH contributes to the induction of tumor-promoting factors and to tumor resistance to ER stress. Increased levels of PRKCSH in various tumor tissues are positively correlated with the expression of XBP1-target genes. Taken together, our data provide a molecular rationale for selective activation of the IRE1α branch in tumors and adaptation of tumor cells to severe environmental stress.
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