Upregulation of Hepatic Glutathione S-Transferase Alpha 1 Ameliorates Metabolic Dysfunction-Associated Steatosis by Degrading Fatty Acid Binding Protein 1.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common metabolic disease of the liver, characterized by hepatic steatosis in more than 5% of hepatocytes. However, despite the recent approval of the first drug, resmetirom, for the management of metabolic dysfunction-associated steatohepatitis, decades of target exploration and hundreds of clinical trials have failed, highlighting the urgent need to find new druggable targets for the discovery of innovative drug candidates against MASLD. Here, we found that glutathione S-transferase alpha 1 (GSTA1) expression was negatively associated with lipid droplet accumulation in vitro and in vivo. Overexpression of GSTA1 significantly attenuated oleic acid-induced steatosis in hepatocytes or high-fat diet-induced steatosis in the mouse liver. The hepatoprotective and anti-inflammatory drug bicyclol also attenuated steatosis by upregulating GSTA1 expression. A detailed mechanism showed that GSTA1 directly interacts with fatty acid binding protein 1 (FABP1) and facilitates the degradation of FABP1, thereby inhibiting intracellular triglyceride synthesis by impeding the uptake and transportation of free fatty acids. Conclusion: GSTA1 may be a good target for the discovery of innovative drug candidates as GSTA1 stabilizers or enhancers against MASLD.

Design, synthesis and triglyceride-lowering activity of tricyclic matrine derivatives for the intervention of non-alcoholic fatty liver disease.

Thirty new tricyclicmatrinic derivatives were successively synthesized and evaluated for their inhibitory activity on the accumulation of triglycerides (TG) in AML12 cells, using 12 N-m-trifluoromethylbenzenesulfonyl matrine (1) as the hit compound. Among the analogues, compound 7n possessing 11-trimethylbutylamine quaternary exerted the highest in vitro TG-lowering potency, as well as a good safety profile. 7n significantly attenuated the hepatic injury and steatosis, and ameliorated dyslipidemia and dysglycemia in the mice with non-alcoholic fatty liver disease (NAFLD) induced by a high-fat diet. Primary mechanism study revealed that upregulation of peroxisome proliferator-activated receptors α (PPARα)-carnitine palmitoyltransferase 1A (CPT1A) pathway mediated the efficacy of 7n. Our study provides powerful information for developing this kind of compound into a new class of anti-NAFLD candidates, and compound 7n is worthy of further investigation as an ideal lead compound.

Bicyclol ameliorates advanced liver diseases in murine models via inhibiting the IL-6/STAT3 signaling pathway.

Bicyclol, a synthetic hepatoprotective and anti-inflammatory agent approved in China, was widely used to treat various hepatitis accompanied by elevated serum aminotransferases. However, the pharmacological effects and mechanisms of bicyclol on advanced liver diseases, such as fibrosis/cirrhosis and hepatocellular carcinoma (HCC), remain to be explored. Here, we revealed that bicyclol prevents from formatting severe fibrosis, slows the progression of moderate liver fibrosis, accelerates the regression of moderate liver fibrosis, decreases the malignancy of HCC in rat models induced by diethylnitrosamine (DEN), and also blocks steatohepatitis to HCC in mice induced by western diet plus carbon tetrachloride and DEN. The detailed pharmacological mechanism showed that bicyclol alleviates chronic progressive liver diseases by inhibiting the levels of IL-6 and subsequent phosphorylated STAT3. Conclusion: Bicyclol plays significant protective roles in multiply stages of fibrosis/cirrhosis-HCC and nonalcoholic fatty liver disease-related HCC via inhibiting IL-6/STAT3 signaling pathway. Therefore, bicyclol might be a promising therapeutic strategy for treating advanced liver diseases.

TGF-ß isoforms inhibit hepatitis C virus propagation in transforming growth factor beta/SMAD protein signalling pathway dependent and independent manners.

Transforming growth factor beta (TGF-ß) plays an important role in the viral liver disease progression via controlling viral propagation and mediating inflammation-associated responses. However, the antiviral activities and mechanisms of TGF-ß isoforms, including TGF-ß1, TGF-ß2 and TGF-ß3, remain unclear. Here, we demonstrated that all of the three TGF-ß isoforms were increased in Huh7.5 cells infected by hepatitis C virus (HCV), but in turn, the elevated TGF-ß isoforms could inhibit HCV propagation with different potency in infectious HCV cell culture system. TGF-ß isoforms suppressed HCV propagation through interrupting several different stages in the whole HCV life cycle, including virus entry and intracellular replication, in TGF-ß/SMAD signalling pathway-dependent and TGF-ß/SMAD signalling pathway-independent manners. TGF-ß isoforms showed additional anti-HCV activities when combined with each other. However, the elevated TGF-ß1 and TGF-ß2, not TGF-ß3, could also induce liver fibrosis with a high expression of type I collagen alpha-1 and α-smooth muscle actin in LX-2 cells. Our results showed a new insight into TGF-ß isoforms in the HCV-related liver disease progression.

IL28A protein homotetramer structure is required for autolysosomal degradation of HCV-NS5A in vitro.

Interferon lambda-2 (IL28A) has a wide antiviral effect with fewer side-effects. Autophagy is a host mechanism to maintain intracellular homeostasis and defends invasion of pathogenic microorganisms. HCV NS5A can disable host defense systems to support HCV replication. Thus, molecular mechanism of interaction among interferon lambda, autophagy, and HCV was concerned and explored in this study. We report that HCV NS5A activated an incomplete autophagy by promoting the autophagic ubiquitylation-like enzymes ATG3, ATG5, ATG7, ATG10, and autophagosome maker LC3B, but blocked autophagy flux; IL28A bound to NS5A at NS5A-ISDR region, and degraded HCV-NS5A by promoting autolysosome formations in HepG2 cells. A software prediction of IL28A protein conformation indicated a potential structure of IL28A homotetramer; the first α-helix of IL28A locates in the interfaces among the four IL28A chains to maintain IL28A homotetrameric conformation. Co-IP and cell immunofluorescence experiments with sequential deletion mutants demonstrate that IL28A preferred a homotetramer conformation to a monomer in the cells; the IL28A homotetramer is positively correlated with autolysosomal degradation of HCV NS5A and the other HCV proteins. Summarily, the first α-helix of IL28A protein is the key domain for maintaining IL28A homotetramer which is required for promoting formation of autolysosomes and degradation of HCV proteins in vitro.

A proof-of-concept study in HCV-infected Huh7.5 cells for shortening the duration of DAA-based triple treatment regimens.

With the development of more effective direct-acting antivirals (DAAs), dual- or triple-therapy regimens represent the major strategy used to cure chronic hepatitis C virus (HCV) infection. Thus, shorter treatment duration regimens with low burden, few adverse effects and good patient adherence are urgently needed. This study theoretically demonstrates a proof-of-concept approach for shortening therapy duration by examining HCV-infected Huh7.5 cells after treatment with a high or low fixed dose of three DAAs (simeprevir + daclatasvir + sofosbuvir) for 6-15 days. The results demonstrated that HCV-infected Huh7.5 cells achieved an ultrarapid virologic response with undetectable HCV RNA and protein and were cured after treatment with the triple-therapy regimen for 15 days. When the treatment duration was shortened, virologic relapse might occur after treatment with a low fixed dose of the three DAAs for 9 days and did occur after treatment with a low fixed dose for 6 days, although HCV was below detectable levels at the end of treatment. However, virologic relapse could be avoided with treatment of a high fixed dose of the three DAAs for 9 or 6 days. Although a virologic breakthrough occurred after an intermittent treatment regimen at the low fixed dose, the high fixed dose cured HCV-positive Huh7.5 cells with intermittent treatment. In conclusion, HCV is persistently present below detectable levels in HCV-infected Huh7.5 cells for a long time after treatment, and a shortened therapy duration is associated with an increased risk of virologic relapse, but virologic relapse or breakthrough might be avoided by treatment with a combination of more highly effective DAAs.

Differential Effects of Autophagy-Related 10 Protein on HCV Replication and Autophagy Flux Are Mediated by Its Cysteine44 and Cysteine135.

Autophagy-related 10 (ATG10) is essential for autophagy since it promotes ATG5-ATG12 complex formation. Our previous study found that there are two isoforms of the ATG10 protein, ATG10 (a longer one) and ATG10S, which have identical sequences except an absence of a 36-amino acid fragment (peptide B) in ATG10S, yet exhibit distinct effects on HCV genome replication. Here, we report the existence of two amino acids, cysteine at residue 44 and 135 (Cys44 and Cys135, respectively), in ATG10 being related to differential effects of ATG10 on HCV replication and autophagy flux. Through a series of ATG10 mutation experiments and protein modeling prediction, we found that Cys44 was involved in the dual role of the two isoforms of ATG10 protein on HCV replication and autophagy flux, and that Cys135 plays similar roles as Cys44, but the disulfide bond of Cys44-Cys135 was not verified in the ATG10 protein. Further analyses by full HCV virion infection confirmed the roles of -SH of Cys44 and Cys135 on HCV replication. ATG10 with deleted or mutated Cys44 and/or Cys135 could activate expression of innate immunity-related genes, including il28a, irf-3, irf-7, and promote complete autophagy by driving autophagosomes to interact with lysosomes via IL28A-mediation. Subcellular localization assay and chromatin immunoprecipitation assay showed that ATG10 with the sulfydryl deletion or substitution of Cys44 and Cys135 could translocate into the nucleus and bind to promoter of IL28A gene; the results indicated that ATG10 with Cys44 and/or Cys135 absence might act as transcriptional factors to trigger the expression of anti-HCV immunological genes, too. In conclusion, our findings provide important information for understanding the differential roles on HCV replication and autophagy flux between ATG10 and ATG10S, and how the structure-function relationship of ATG10 transformed by a single -SH group loss on Cys44 and Cys135 in ATG10 protein, which may be a new target against HCV replication.

Hepatitis C: From inflammatory pathogenesis to anti-inflammatory/hepatoprotective therapy.

Hepatitis C virus (HCV) infection commonly causes progressive liver diseases that deteriorate from chronic inflammation to fibrosis, cirrhosis and even to hepatocellular carcinoma. A long-term, persistent and uncontrolled inflammatory response is a hallmark of these diseases and further leads to hepatic injury and more severe disease progression. The levels of inflammatory cytokines and chemokines change with the states of infection and treatment, and therefore, they may serve as candidate biomarkers for disease progression and therapeutic effects. The mechanisms of HCV-induced inflammation involve classic pathogen pattern recognition, inflammasome activation, intrahepatic inflammatory cascade response, and oxidative and endoplasmic reticulum stress. Direct-acting antivirals (DAAs) are the first-choice therapy for effectively eliminating HCV, but DAAs alone are not sufficient to block the uncontrolled inflammation and severe liver injury in HCV-infected individuals. Some patients who achieve a sustained virologic response after DAA therapy are still at a long-term risk for progression to liver cirrhosis and hepatocellular carcinoma. Therefore, coupling with anti-inflammatory/hepatoprotective agents with anti-HCV effects is a promising therapeutic regimen for these patients during or after treatment with DAAs. In this review, we discuss the relationship between inflammatory mediators and HCV infection, summarize the mechanisms of HCV-induced inflammation, and describe the potential roles of anti-inflammatory/hepatoprotective drugs with anti-HCV activity in the treatment of advanced HCV infection.

Discovery and evolution of aloperine derivatives as a new family of HCV inhibitors with novel mechanism.

Aloperine (1), a Chinese natural product with a unique endocyclic scaffold, was first identified to be a potent hepatitis C virus (HCV) inhibitor in our laboratory. Thirty-four new aloperine derivatives were designed, synthesized and evaluated for their anti-HCV activities taking 1 as the lead. Among them, compound 7f exhibited the potential potency with EC50 values in a micromolar range against both wild-type and direct-acting antiviral agents (DAAs)-resistant variants, and synergistically inhibited HCV replication with approved DAAs. Furthermore, it also owned a good oral pharmacokinetic and safety profile, suggesting a highly druglike nature. The primary mechanism showed that 7f might target host components, distinctly different from the DAAs currently used in clinic. Therefore, we consider aloperine derivatives to be a novel class of anti-HCV agents, and compound 7f has been selected as a promising antiviral candidate for further investigation.

Internal driving factors leading to extrahepatic manifestation of the hepatitis C virus infection.

The hepatitis C virus (HCV) infection is associated with various extrahepatic manifestations, which are correlated with poor outcomes, and thus increase the morbidity and mortality of chronic hepatitis C (CHC). Therefore, understanding the internal linkages between systemic manifestations and HCV infection is helpful for treatment of CHC. Yet, the mechanism by which the virus evokes the systemic diseases remains to be elucidated. In the present study, using gene set enrichment analysis (GSEA) and signaling pathway impact analysis (SPIA), a comprehensive analysis of microarray data of mRNAs was conducted in HCV-infected and -uninfected Huh7.5 cells, and signaling pathways (which are significantly activated or inhibited) and certain molecules (which are commonly important in those signaling pathways) were selected. Forty signaling pathways were selected using GSEA, and eight signaling pathways were selected with SPIA. These pathways are associated with cancer, metabolism, environmental information processing and organismal systems, which provide important information for further clarifying the intrinsic associations between syndromes of HCV infection, of which seven pathways were not previously reported, including basal transcription factors, pathogenic Escherichia coli infection, shigellosis, gastric acid secretion, dorso-ventral axis formation, amoebiasis and cholinergic synapse. Ten genes, SOS1, RAF1, IFNA2, IFNG, MTHFR, IGF1, CALM3, UBE2B, TP53 and BMP7 whose expression may be the key internal driving molecules, were selected using the online tool Anni 2.1. Furthermore, the present study demonstrated the internal linkages between systemic manifestations and HCV infection, and presented the potential molecules that are key to those linkages.

Design and Synthesis of Cajanine Analogues against Hepatitis C Virus through Down-Regulating Host Chondroitin Sulfate N-Acetylgalactosaminyltransferase 1.

There still remains a need to develop new anti-HCV agents with distinct mechanism of action (MOA) due to the occurrence of resistance to direct-acting antiviral agents (DAAs). Cajanine, a stilbenic component isolated from Cajanus cajan L., was identified as a potent HCV inhibitor by phenotypic screening in this work (EC50 = 3.17 ± 0.75 µM). The intensive structure optimization provided significant insights into the structure-activity relationships. Furthermore, the MOA study revealed that cajanine inhibited HCV replications via down-regulating a cellular protein chondroitin sulfate N-acetylgalactosaminyltransferase 1. In consistency with this host-targeting mechanism, cajanine showed the similar magnitude of inhibitory activity against both drug-resistant and wild-type HCV and synergistically inhibited HCV replication with approved DAAs. Taken together, our study not only presented cajanine derivatives as a novel class of anti-HCV agents but also discovered a promising anti-HCV target to combat drug resistance.

CD36 is a co-receptor for hepatitis C virus E1 protein attachment.

The cluster of differentiation 36 (CD36) is a membrane protein related to lipid metabolism. We show that HCV infection in vitro increased CD36 expression in either surface or soluble form. HCV attachment was facilitated through a direct interaction between CD36 and HCV E1 protein, causing enhanced entry and replication. The HCV co-receptor effect of CD36 was independent of that of SR-BI. CD36 monoclonal antibodies neutralized the effect of CD36 and reduced HCV replication. CD36 inhibitor sulfo-N-succinimidyl oleate (SSO), which directly bound CD36 but not SR-BI, significantly interrupted HCV entry, and therefore inhibited HCV replication. SSO's antiviral effect was seen only in HCV but not in other viruses. SSO in combination with known anti-HCV drugs showed additional inhibition against HCV. SSO was considerably safe in mice. Conclusively, CD36 interacts with HCV E1 and might be a co-receptor specific for HCV entry; thus, CD36 could be a potential drug target against HCV.

MicroRNA-mediated interactions between host and hepatitis C virus.

MicroRNAs (miRNAs) are small noncoding RNAs. More than 2500 mature miRNAs are detected in plants, animals and several types of viruses. Hepatitis C virus (HCV), which is a positive-sense, single-stranded RNA virus, does not encode viral miRNA. However, HCV infection alters the expression of host miRNAs, either in cell culture or in patients with liver disease progression, such as liver fibrosis, cirrhosis, and hepatocellular carcinoma. In turn, host miRNAs regulate HCV life cycle through directly binding to HCV RNAs or indirectly targeting cellular mRNAs. Increasing evidence demonstrates that miRNAs are one of the centered factors in the interaction network between virus and host. The competitive viral and host RNA hypothesis proposes a latent cross-regulation pattern between host mRNAs and HCV RNAs. High loads of HCV RNA sequester and de-repress host miRNAs from their normal host targets and thus disturb host gene expression, indicating a means of adaptation for HCV to establish a persistent infection. Some special miRNAs are closely correlated with liver-specific disease progression and the changed levels of miRNAs are even higher sensitivity and specificity than those of traditional proteins. Therefore, some of them can serve as novel diagnostic/prognostic biomarkers in HCV-infected patients with liver diseases. They are also attractive therapeutic targets for development of new anti-HCV agents.

[The influence of intracellular keratin 8 on hepatitis C virus replication].

The level of intracellular keratin 8(KRT-8) is associated with liver diseases, whose expression is increased in hepatitis C virus(HCV)-infected patients with hepatocarcinoma and in cultural cells infected with HCV. However, it is not clear whether KRT-8 will impact HCV replication. In this paper, the HCV replication was analyzed in response to high expression and silence of KRT-8. The inhibitory activities against wild-type and mutant HCV were also analyzed by silence of KRT-8 or combined with known anti-HCV drug telaprevir. Results showed that the protein level of KRT-8 was increased in proportion with the HCV replication. The high expression was found to facilitate HCV replication, while the silence of KRT-8 was able to inhibit HCV replication and enhanced the anti-HCV activity of telaprevir. It also inhibited A156 T and D168 V mutant HCV, which are resistant to protease inhibitors. These results suggest that KRT-8 is a co-factor for HCV replication. Down-regulation of KRT-8 can inhibit wild type and mutant HCV replication to enhance the anti-HCV activity of known anti-HCV drugs. Therefore, KRT-8 may be a new target in the development of anti-HCV agents.

A zebrafish model for subgenomic hepatitis C virus replication.

Persistent infection with hepatitis C virus (HCV) is a major risk factor in the development of hepatocellular carcinoma. The elucidation of the pathogenesis of HCV-associated liver disease is hampered by the absence of an appropriate small animal model. Zebrafish exhibits high genetic homology to mammals, and is easily manipulated experimentally. In this study, we describe the use of a zebrafish model for the analysis of HCV replication mechanisms. As the 5' untranslated region (UTR), the core protein, the non-structural protein 5B (NS5B) and the 3'UTR are essential for HCV replication, we constructed a HCV sub-replicon gene construct including the 4 gene sequences and the enhanced green fluorescent protein (EGFP) reporter gene; these genes were transcribed through the mouse hepatocyte nuclear factor 4 (mHNF4) promoter. By microinjection of the subgenomic replicon vector into zebrafish larvae, the virus was easily detected by observing EGFP fluorescence in the liver. The positive core and NS5B signals showed positive expression of the HCV gene construct in zebrafish by reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. Importantly, the negative strand sequence of the HCV subgenomic RNA was detected by RT-PCR and hybridization in situ, demonstrating that the HCV sub-replicon has positive replication activity. Furthermore, the hybridization signal mainly appeared in the liver region of larvae, as detected by the sense probe of the core protein or NS5B, which confirmed that the sub-replicon amplification occurred in the zebrafish liver. The amplification of the sub-replicon caused alterations in the expression of certain genes, which is similar to HCV infection in human liver cells. To verify the use of this zebrafish model in drug evaluation, two drugs against HCV used in clinical practice, ribavirin and oxymatrine, were tested and these drugs showed significant inhibition of replication of the HCV sub-replicon in the larvae. In conclusion, this zebrafish model of HCV may prove to be a novel and simple in vivo model for the study of the mechanisms of HCV replication and may also prove useful in the disovery of new anti-HCV drugs.

[Recent advances in the study of mechanism of APOBEC3G against virus].

APOBEC3 is a class of cytidine deaminase, which is considered as a new member of the innate immune system, and APOBEC3G belongs to this family. The research about APOBEC3G is a new direction of innate immune defense mechanism against virus. APOBEC3G has the restrictive activity on many viral replications, which deaminates dC to dU in the viral genome and then induces extensive hypermutation. APOBEC3G can also interrupt viral replication at several phases such as reverse transcription, replication, nucleocapsid and so on by non-deamination mechanisms. However, virus can encode viral proteins to counteract the restriction activity of APOBEC3G. Elucidation of the antagonistic interaction between APOBEC3G and the virus will be contributed to development of new antiviral drugs in the future.

HCV IRES-mediated core expression in zebrafish.

The lack of small animal models for hepatitis C virus has impeded the discovery and development of anti-HCV drugs. HCV-IRES plays an important role in HCV gene expression, and is an attractive target for antiviral therapy. In this study, we report a zebrafish model with a biscistron expression construct that can co-transcribe GFP and HCV-core genes by human hepatic lipase promoter and zebrafish liver fatty acid binding protein enhancer. HCV core translation was designed mediated by HCV-IRES sequence and gfp was by a canonical cap-dependent mechanism. Results of fluorescence image and in situ hybridization indicate that expression of HCV core and GFP is liver-specific; RT-PCR and Western blotting show that both core and gfp expression are elevated in a time-dependent manner for both transcription and translation. It means that the HCV-IRES exerted its role in this zebrafish model. Furthermore, the liver-pathological impact associated with HCV-infection was detected by examination of gene markers and some of them were elevated, such as adiponectin receptor, heparanase, TGF-ß, PDGF-α, etc. The model was used to evaluate three clinical drugs, ribavirin, IFNα-2b and vitamin B12. The results show that vitamin B12 inhibited core expression in mRNA and protein levels in dose-dependent manner, but failed to impact gfp expression. Also VB12 down-regulated some gene transcriptions involved in fat liver, liver fibrosis and HCV-associated pathological process in the larvae. It reveals that HCV-IRES responds to vitamin B12 sensitively in the zebrafish model. Ribavirin did not disturb core expression, hinting that HCV-IRES is not a target site of ribavirin. IFNα-2b was not active, which maybe resulted from its degradation in vivo for the long time. These findings demonstrate the feasibility of the zebrafish model for screening of anti-HCV drugs targeting to HCV-IRES. The zebrafish system provides a novel evidence of using zebrafish as a HCV model organism.

Host apolipoprotein B messenger RNA-editing enzyme catalytic polypeptide-like 3G is an innate defensive factor and drug target against hepatitis C virus.

UNLABELLED: Host cellular factor apolipoprotein B messenger RNA (mRNA)-editing enzyme catalytic polypeptide-like 3G (hA3G) is a cytidine deaminase that inhibits a group of viruses including human immunodeficiency virus-1 (HIV-1). In the continuation of our research on hA3G, we found that hA3G stabilizing compounds significantly inhibited hepatitis C virus (HCV) replication. Therefore, this study investigated the role of hA3G in HCV replication. Introduction of external hA3G into HCV-infected Huh7.5 human hepatocytes inhibited HCV replication; knockdown of endogenous hA3G enhanced HCV replication. Exogenous HIV-1 virion infectivity factor (Vif) decreased intracellular hA3G and therefore enhanced HCV proliferation, suggesting that the presence of Vif might be an explanation for the HIV-1/HCV coinfection often observed in HIV-1(+) individuals. Treatment of the HCV-infected Huh7.5 cells with RN-5 or IMB-26, two known hA3G stabilizing compounds, increased intracellular hA3G and accordingly inhibited HCV replication. The compounds inhibit HCV through increasing the level of hA3G incorporated into HCV particles, but not through inhibiting HCV enzymes. However, G/A hypermutation in the HCV genome were not detected, suggesting a new antiviral mechanism of hA3G in HCV, different from that in HIV-1. Stabilization of hA3G by RN-5 was safe in vivo. CONCLUSION: hA3G appears to be a cellular restrict factor against HCV and could be a potential target for drug discovery.

Oxymatrine inhibits hepatitis B infection with an advantage of overcoming drug-resistance.

Oxymatrine (OMTR) is an anti-hepatitis drug used in China. Its mechanism of action is unknown. Recently, we found that OMTR inhibits hepatitis B virus (HBV) via down-regulating the expression of heat-stress cognate 70 (Hsc70), a host protein required for HBV DNA replication. Goal of this study was to assess the effect of OMTR on clinical HBV drug-resistance. OMTR monotherapy (oral, 12 months) reduced blood HBV DNA by 96% and HBeAg by 70% in the chronic hepatitis B (CHB) patients resistant to lamivudine (n = 17), equal to its efficacy in the naïve CHB cohort (n = 20). Liver biopsy study showed that OMTR treatment caused a decrease of Hcs70 mRNA in liver cells, parallel with a reduction of intracellular HBV DNA. Combination of lamivudine with OMTR (n = 15) (oral, 12 months) showed an enhanced anti-HBV effect as compared to lamivudine monotherapy (n = 25). The incidence of drug resistance against lamivudine in the combination group was significantly lower than that in the lamivudine group (1/15 vs 7/25; p<0.01). The results were further confirmed in vitro. Treatment of HBV(+) HepH2215 cells with sub-optimal dose of OMTR for 8 months suppressed HBV replication without inducing drug resistance, whereas lamivudine monotherapy caused drug-resistant mutation in 3 months. Combination of OMTR with lamivudine prevented HBV from developing drug resistance.

Design and synthesis of oxymatrine analogues overcoming drug resistance in hepatitis B virus through targeting host heat stress cognate 70.

Heat-stress cognate 70 (Hsc70) is a host protein required for hepatitis B virus (HBV) replication, and oxymatrine (1) suppresses Hsc70 expression. Taking Hsc70 as a target against HBV, 22 analogues of 1 defined with substituents at position 1, 13, or 14 were synthesized and evaluated for their activity on Hsc70 mRNA expression. The SAR revealed that (i) the oxygen atom at the 1-position was not essential, (ii) increasing electron density on the ring D reduced the activity, and (iii) introducing a proper substituent at the 13- and/or 14-position(s), especially electron-withdrawing groups, might enhance the activity. Among the analogues, 6b possessing 13-ethoxyl afforded an increased activity in respect to 1. Importantly, it was active for either wild-type or lamivudine-resistant HBV, as its target is host Hsc70 but not viral enzymes. LD(50) of 6b in mice was over 750 mg/kg in oral route. We consider compound 6b promising for further investigation.