Design, synthesis, and anti-tumor activity of derivatives of ring A and C-28 of asiatic acid.

Based on computer-aided drug design (CADD), the active groups of the known active small molecule compounds that can bind to EGFR target protein were analyzed through the molecular docking method. Then, 12 novel asiatic acid derivatives were synthesized by introducing active groups at ring A and C-28 positions of asiatic acid. The structures of these novel compounds were determined by NMR and MS. Furthermore, the anti-tumor activities of these derivatives on human lung cancer cells (A549) and human breast cancer cells (MCF-7) were evaluated by MTT assay. In conclusion, compounds I4 and II3 have stronger anti-cancer activity than parent compounds, the activities were stronger than gefitinib and comparable to afatinib, which may be potential candidate compounds for tumor therapy.

Nucleos(t)ide analogues altered quasispecies composition of hepatitis B virus (HBV)-resistant mutations in serum HBV DNA and serum HBV RNA.

Serum hepatitis B virus (HBV) RNA is a new serological indicator reflecting viral replication with good clinical application prospects. This study aimed to clarify the dynamic changes of serum HBV RNA levels and the quasispecies of HBV RNA virus-like particles in nucleos(t)ide analogues (NAs)-experienced chronic hepatitis B (CHB) patients harboring NAs-resistant mutations and their identifiable effects on NAs resistance. We included CHB patients who were on long-term NAs treatment and with HBV DNA rebound. The longitudinally dynamics of serum HBV RNA levels were quantitatively detected, and the quasispecies differences between serum HBV DNA and serum HBV RNA were compared by high-throughput sequencing. The effect of NAs concentration pressure on altering the resistance mutations quasispecies proportion of HBV DNA and HBV RNA in cell supernatant was analyzed in vitro. A total of 447 serum samples from 36 CHB patients treated with NAs were collected. The median follow-up period was 47 months (about 4 years), and the longest follow-up period was 117 months (about 10 years). Our results showed that HBV RNA could reflect virological breakthrough in 23 (64%, 23/36) patients, and serum HBV RNA rebound earlier than HBV DNA in 12 (52%, 12/23) patients. However, serum HBV RNA remained at a consistently high level and did not fluctuate significantly with the HBV DNA rebound in 6 of 36 patients. In addition, serum HBV RNA was not consistently detectable in 7 of the 36 patients, and their serum HBV RNA was undetectable even after HBV DNA had rebounded. The proportion of drug-resistant mutations in HBV DNA was higher than that of HBV RNA by high-throughput sequencing. The results of in vitro experiments showed that the viral strains with drug-resistant mutation in HBV DNA in cell supernatants gradually become the dominant strains with the increase of NAs concentrations. Serum HBV RNA levels can reflect virological breakthrough in most NAs- treated CHB patients, but there are certain limitations. NAs alter the quasispecies composition of serum HBV DNA and serum HBV RNA, resulting in a higher detection rate of drug-resistant mutations in serum HBV DNA than in serum HBV RNA.

Design, synthesis, and antitumor activity of novel oleanolic acid analogues targeting EGFR.

Based on the simulated docking of Epidermal growth factor receptor inhibitors with known active small molecule compounds, computer-aided drug design technology was used to analyze key amino acid fragments and determine the active groups binding with key sites. Then, twelve novel analogues of oleanolic acid (OA) were synthesized by introducing active groups at the C-3 and C-28 positions of OA. The structures of these novel analogues were confirmed by NMR and MS. Furthermore, the antitumor activities of these novel analogues were evaluated by MTT assay. As a result, compounds I3 and II3 showed stronger cytotoxicity on tumor cells than positive controls. In conclusion, our study synthesized twelve novel analogues of OA and determined compounds I3 and II3 had better antitumor effect, which may be potential candidate compounds for tumor therapy.

Synthesis and anti-tumor activity of asiatic acid derivatives targeting VEGFR.

To discovery novel VEGFR inhibitors, 12 novel asiatic acid derivatives were designed by computer-aided drug design (CADD) technology. Then, these novel asiatic acid derivatives were synthesized by introducing active groups at ring A and C-28 positions of asiatic acid. The structures of these novel analogues were confirmed by NMR and MS. Moreover, the anti-tumor activities of these novel asiatic acid derivatives on human hepatoma cells HepG2 and human gastric cancer cells SGC7901 were evaluated by MTT assay. As a result, compounds I2 and II4 showed stronger cytotoxicity on tumor cells than asiatic acid and positive control drugs such as gefitinib and paclitaxel. In conclusion, our study synthesized twelve novel asiatic acid derivatives and determined compounds I2 and II4 had better anti-tumor effect which may be potential candidate compounds for tumor therapy.

Identification of functional circRNA/miRNA/mRNA regulatory network for exploring prospective therapy strategy of colorectal cancer.

Circular RNA (circRNA) has been reported to have great scientific significance and clinical value in multiple cancers including colorectal cancer (CRC). However, the biological function of most circRNAs in CRC is still in its infancy. Herein, we discovered the differential expressed circRNAs (DECs) between CRC tissues and matched adjacent using deep RNA sequencing and further confirmed the DECs expression by combining with another Gene Expression Omnibus dataset. Furthermore, we validated the expression of the top four upregulated circRNAs (hsa_circ_0030632, hsa_circ_0004887, hsa_circ_0001550, and hsa_circ_0001681) in both of paired CRC tissues and CRC cell lines. Then, a circRNA/microRNA/messenger RNA regulatory network was established and the Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed these four circRNAs participated in various biological processed including apoptotic process and multiple metabolic processes. Moreover, based on the regulatory network, three bioactive compounds (pergolide, pivampicillin, and methylergometrine) for the treatment of CRC were also found. In conclusion, this study improved our understanding of circRNAs and may also facilitate the finding of promising targets and biomarkers in CRC.

Role of acute-phase protein ORM in a mice model of ischemic stroke.

The only Food and Drug Administration-approved treatment for acute ischemic stroke is tissue plasminogen activator, and the discovery of novel therapeutic targets is critical. Here, we found orosomucoid (ORM), an acute-phase protein mainly produced by the liver, might act as a treatment candidate for an ischemic stroke. The results showed that ORM2 is the dominant subtype in mice normal brain tissue. After middle cerebral artery occlusion (MCAO), the level of ORM2 is significantly increased in the ischemic penumbra compared with the contralateral normal brain tissue, whereas ORM1 knockout did not affect the infarct size. Exogenous ORM could significantly decrease infarct size and neurological deficit score. Inspiringly, the best administration time point was at 4.5 and 6 hr after MCAO. ORM could markedly decrease the Evans blue extravasation, and improve blood-brain barrier-associated proteins expression in the ischemic penumbra of MACO mice and oxygen-glucose deprivation (OGD)-treated bEnd3 cells. Meanwhile, ORM could significantly alleviate inflammation by inhibiting the production of interleukin 1ß (IL-1ß), IL-6, and tumor necrosis factor α (TNF-α), reduce oxidative stress by improving the balance of malondialdehyde (MDA) and superoxide dismutase (SOD), inhibit apoptosis by decreasing caspase-3 activity in ischemic penumbra of MCAO mice and OGD-treated bEnd.3 cells. Because of its protective role at multiple levels, ORM might be a promising therapeutic target for ischemic stroke.

CD8+ T-Cell Response-Associated Evolution of Hepatitis B Virus Core Protein and Disease Progress.

Under the immune pressure of cytotoxic T cells (CTLs), hepatitis B virus (HBV) evolves to accumulate mutations more likely within epitopes to evade immune detection. However, little is known about the specific patterns of the immune pressure-associated HBV mutation of T-cell epitopes and their link to disease progression. Here, we observed a correlation of the accumulated variants on HBV core protein (HBc) with the disease severity of HBV infection. Further analysis indicated that these substitutions were mostly located within CD8+ T-cell epitopes of HBc protein, which were systematically screened and identified in an unbiased manner in our study. From individual peptide level to the human leukocyte antigen I (HLA-I)-restricted population level, we elucidated that the mutations in these well-defined HLA-I-restricted T-cell epitopes significantly decreased antiviral activity-specific CTLs and were positively associated with clinical parameters and disease progression in HBV-infected patients. The molecular pattern for viral epitope variations based on the sequencing of 105 HBV virus genomes indicated that the C-terminal portion (Pc), especially the Pc-1 and Pc-2 positions, have the highest mutation rates. Further structural analysis of HLA-A*02 complexed to diverse CD8+ T-cell epitopes revealed that the highly variable C-terminal bulged peak of M-shaped HBc-derived epitopes are solvent exposed, and most of the CDR3ßs of the T-cell receptor hover over them. These data shed light on the molecular and immunological mechanisms of T-cell immunity-associated viral evolution in hepatitis B progression, which is beneficial for designing immunotherapies and vaccines.IMPORTANCE The specific patterns of sequence polymorphisms of T-cell epitopes and the immune mechanisms of the HBV epitope mutation-linked disease progression are largely unclear. In this study, we systematically evaluated the contribution of CD8+ T cells to the disease progress-associated evolution of HBV. By evaluation of patient T-cell responses based on the peptide repertoire, we comprehensively characterized the association of clinical parameters in chronic hepatitis B with the antiviral T-cell response-associated mutations of the viruses from the single-epitope level to the overall HLA-I-restricted peptide levels. Furthermore, we investigated the molecular basis of the HLA-A2-restricted peptide immune escape and found that the solvent-exposed C-terminal portion of the epitopes is highly variable under CDR3ß recognition. Our work may provide a comprehensive evaluation of viral mutations impacted by the host CTL response in HBV disease progression in the context of the full repertoire of HBc-derived epitopes.

Antigenicity reduction contributes mostly to poor detectability of HBsAg by hepatitis B virus (HBV) S-gene mutants isolated from individuals with occult HBV infection.

Mutations in hepatitis B virus (HBV) S gene are one of factors contributing to occult HBV infection (OBI). The study aimed to uncover the impact of OBI-related S-gene mutations on the detectability of hepatitis B surface antigen (HBsAg). Nine representative mutations within the major hydrophilic region of the S region were investigated. These included six (M1-M6) from an OBI patient with HBV-related hepatocellular carcinoma, and three (M7-M9) from three OBI blood donors. Recombinant plasmids on the basis of pTriEx-mod-1.1 HBV and pcDNA3.1(-)/myc-His A vectors were constructed for each and transfected into HepG2 or Huh7 cells, respectively. Electrochemical luminescence, ELISA, Western blotting, and confocal immunofluorescence were used to examine HBsAg expression and antigenicity. In comparison to wild-type strain, supernatant and intracellular HBsAg levels of the nine mutants were reduced by 56.39-99.09% and 42.76-99.77% upon Roche quantitative Elecsys assay, respectively. Confocal immunofluorescence showed that relative intensity ratios of HBsAg-myc-His fusion protein detected by anti-HBs and anti-His-tag were lower by 11.87-76.27% for the nine mutants compared to the wild-type strain. Specifically, M1-M5 mutants that we firstly found recently were 33.14%, 76.27%, 57.93%, 53.37%, and 40.88% lower, respectively. Consistent results were obtained using double-antibody sandwich ELISA assays (anti-myc + anti-HBs vs anti-myc + anti-His). Antigenicity reduction played a major role for the poor detectability of HBsAg caused by the OBI-related mutations, although decreased HBsAg expression of some mutants and anti-HBs in samples might play coordinated roles. Taken together, antigenicity reduction contributes mostly to poor detectability of HBsAg caused by these OBI-related mutations.

Clinical and virological implications of A1846T and C1913A/G mutations of hepatitis B virus genome in severe liver diseases.

OBJECTIVE: Mutations occurring within different genes of hepatitis B virus (HBV) genome may have different clinical implications. This study aimed to observe the clinical and virological implications of the A1846T and C1913A/G mutations of HBV genome in the development and treatment outcome of severe liver diseases, which has not been previously determined. MATERIALS AND METHODS: A total of 438 cases of patients with liver diseases were retrospectively reviewed, including 146 with mild chronic hepatitis B infection (CHB-M), 146 with severe chronic hepatitis B infection (CHB-S), and 146 with acute-on-chronic liver failure (ACLF). Partial or full-length HBV genome was directly sequenced. Replicons containing A1846T, C1913A or other mutant sequences, or the wild-type counterparts were constructed respectively, and then transfected into HepG2 cells for phenotype analysis. RESULTS: There was significant difference in the detection rates of A1846T (30.82%, 40.41% and 55.48%, respectively) and C1913A/G (15.52%, 28.77%, and 35.62%, respectively) among patients with CHB-M, those with CHB-S, and those with ACLF (p < .01). A1846T was significantly associated with the mortality of ACLF patients within six months after the disease onset (OR 1.704, p = .041). In vitro experiment revealed that A1846T mutant resulted in 3.20-fold and 1.85-fold increase of replication capacity and promoter activity, respectively compared with wild type counterpart (p < .001), while C1913A led to a significant decrease of core protein expression (p < .05). CONCLUSION: Occurrence of A1846T and C1913A is positively associated with clinical presentations of severe liver disease. A1846T mutation is significantly associated with poor prognosis of ACLF.

Intergenotype recombinant analysis of full-length hepatitis B virus genomes from 516 Chinese patients with different illness categories.

This study aimed to reveal characteristics and clinical relevance of HBV intergenotypic recombinants. Serum samples of 516 patients from Northern China were collected, including 131 with acute hepatitis B (AHB), 239 with chronic hepatitis B (CHB), and 146 with acute-on-chronic liver failure (ACLF). Full-length HBV genomes were sequenced and HBV genotypes were analyzed. Genotypes C, B, D, and intergenotypic recombinants were detected in 71.12% (367/516), 19.96% (103/516), 0.78% (4/516), and 8.14% (42/516) of the patients. The latter comprised 21 with AHB, 10 with CHB, and 11 with ACLF; and the occupations of intergenotypic recombinants in AHB, CHB, and ACLF groups were 16.03%, 4.18%, and 7.53% (P < 0.01), respectively. HBV B/C and C/D hybrids accounted for 85.71% (36/42) and 14.29% (6/42) of the intergenotypic recombinants. In AHB and CHB groups, serum HBV DNA levels were significantly lower in patients with intergenotypic recombinants than those without intergenotypic recombinants. Difference in basal core promoter A1762T/G1764A mutations and precore G1896A mutation incidences was not significant between B/C recombinant and genotypes B or C virus, although the significance was there between genotypes B and C viruses. Clonal sequence analysis showed that intergenotypic recombinant viral strains existed in single or in concomitance with other genotype virus. Phenotypic analysis showed that viral replication capacity was similar between recombinant and non-recombinant strains in tested samples. Taken together, the occurrence of intergenotypic recombinant HBV is relatively low in HBV-infected patients in Northern China, and intergenotypic recombinant HBV infection is likely favorable to induce an acute course of disease. J. Med. Virol. 89:139-145, 2017. © 2016 Wiley Periodicals, Inc.

Characterization of hepatitis B virus (HBV) preS/S gene mutations in blood donors with occult HBV infection in the Baoji area of North China.

BACKGROUND: Occult hepatitis B virus (HBV) infection (OBI) in blood donors was investigated in the Baoji area of North China, and OBI-related viral mutations in donors were characterized. STUDY DESIGN AND METHODS: In total, 110,843 blood donor samples that were consecutively collected from December 2011 to March 2015 at the Baoji Blood Center were examined. Hepatitis B surface antigen-negative and HBV DNA-positive OBI samples were amplified for sequence analysis of OBI-related mutations in the HBV preS/S region. HBV genomes from 108 adult patients with chronic hepatitis B from North China were used as controls. RESULTS: OBI was detected in 60 (1:1847) individual blood donors. All OBI samples were negative for hepatitis B e-antigen, and 55 were positive for anti-hepatitis B core antigen. The preS/S genes were successfully sequenced for 43 OBI samples. OBI-related S gene mutations in the major hydrophilic region were detected more frequently in blood donors with OBI than that in controls (51.16 vs. 12.96%; p < 0.01). Specifically, the incidence of five OBI-related major hydrophilic region mutations (sS117T, sT118K, sT131N, sT134Y/L, and sD144E) was significantly higher in blood donors with OBI than in controls. In addition, the coexistence of multiple OBI-related mutations in the major hydrophilic region was detected more frequently in donors than in controls (30.23 vs. 1.85%; p < 0.01), and preS deletions greater than 33 base pairs also were detected more frequently in blood donors with OBI than in controls. CONCLUSION: OBI in blood donors should be addressed attentively in the Baoji area of North China, and HBV preS/S gene mutations may play an important role in OBI prevalence in the area.

Effects and Mechanisms of Fruit and Vegetable Juices on Cardiovascular Diseases.

Many studies have indicated that consumption of vegetables and fruits are positively related to lower incidence of several chronic noncommunicable diseases. Although composition of fruit and vegetable juices is different from that of the edible portion of fruits and vegetables, they contain polyphenols and vitamins from fruits and vegetables. Drinking vegetable and fruit juices is very popular in many countries, and also an efficient way to improve consumption of fruits and vegetables. The studies showed that fruit and vegetable juices affect cardiovascular risk factors, such as lowering blood pressure and improving blood lipid profiles. The main mechanisms of action included antioxidant effects, improvement of the aspects of the cardiovascular system, inhibition of platelet aggregation, anti-inflammatory effects, and prevention of hyperhomocysteinemia. Drinking juices might be a potential way to improve cardiovascular health, especially mixtures of juices because they contain a variety of polyphenols, vitamins, and minerals from different fruits and vegetables. This review summarizes recent studies on the effects of fruit and vegetable juices on indicators of cardiovascular disease, and special attention is paid to the mechanisms of action.

Effects of Melatonin on Liver Injuries and Diseases.

Liver injuries and diseases are serious health problems worldwide. Various factors, such as chemical pollutants, drugs, and alcohol, could induce liver injuries. Liver diseases involve a wide range of liver pathologies, including hepatic steatosis, fatty liver, hepatitis, fibrosis, cirrhosis, and hepatocarcinoma. Despite all the studies performed up to now, therapy choices for liver injuries and diseases are very few. Therefore, the search for a new treatment that could safely and effectively block or reverse liver injuries and diseases remains a priority. Melatonin is a well-known natural antioxidant, and has many bioactivities. There are numerous studies investigating the effects of melatonin on liver injuries and diseases, and melatonin could regulate various molecular pathways, such as inflammation, proliferation, apoptosis, metastasis, and autophagy in different pathophysiological situations. Melatonin could be used for preventing and treating liver injuries and diseases. Herein, we conduct a review summarizing the potential roles of melatonin in liver injuries and diseases, paying special attention to the mechanisms of action.

Natural Antioxidants in Foods and Medicinal Plants: Extraction, Assessment and Resources.

Natural antioxidants are widely distributed in food and medicinal plants. These natural antioxidants, especially polyphenols and carotenoids, exhibit a wide range of biological effects, including anti-inflammatory, anti-aging, anti-atherosclerosis and anticancer. The effective extraction and proper assessment of antioxidants from food and medicinal plants are crucial to explore the potential antioxidant sources and promote the application in functional foods, pharmaceuticals and food additives. The present paper provides comprehensive information on the green extraction technologies of natural antioxidants, assessment of antioxidant activity at chemical and cellular based levels and their main resources from food and medicinal plants.

Optimization of Ultrasound-Assisted Extraction of Antioxidants from the Mung Bean Coat.

Mung bean (Vigna radiata) sprout is commonly consumed as a vegetable, while the coat of the germinated mung bean is a waste. In this paper, an ultrasound-assisted extraction method has been developed to extract natural antioxidants from the seed coat of mung bean. Several experimental parameters-which included ethanol concentration, solvent/material ratio, ultrasound extraction time, temperature, and power-were studied in single-factor experiments. The interaction of three key experimental parameters (ethanol concentration, solvent/material ratio, and ultrasonic extraction time) was further investigated by response surface method. Besides, traditional extracting methods, including maceration and Soxhlet extraction methods, were also carried out for comparison. The results suggested that the best extracting condition was 37.6% (v/v) of ethanol concentration, 35.1:1 mL/g of solvent/material ratio and ultrasonic extraction of 46.1 min at 70 °C under 500 W ultrasonic irradiation. The antioxidant capacity (178.28 ± 7.39 µmol Trolox/g DW) was much stronger than those obtained by the maceration extraction process (158.66 ± 4.73 µmol Trolox/g DW) and the Soxhlet extraction process (138.42 ± 3.63 µmol Trolox/g DW). In addition, several antioxidant components in the extract were identified and quantified. This study is helpful for value-added utilization of the waste from germinated mung bean.

Ultrasound-Assisted Extraction and Identification of Natural Antioxidants from the Fruit of Melastoma sanguineum Sims.

The fruit of Melastoma sanguineum Sims is an edible and sweet wild fruit. In our previous study, the fruit was found to have a strong antioxidant property. In this study, an ultrasound-assisted extraction (UAE) method was developed to extract natural antioxidants from the fruit of Melastoma sanguineum Sims, and a response surface methodology was used to optimize the conditions of UAE to maximize the extraction efficiency. The influence of five independent extraction parameters (ethanol concentration, solvent/material ratio, extracting time, temperature, and ultrasound power) on the extraction efficiency were investigated using a single factor experiment, and then a central composite rotatable design was used to investigate the interaction of three key parameters. The results showed that the optimal extraction conditions were 42.98% ethanol, 28.29 mL/g solvent/material ratio, 34.29 min extracting time, 60 °C temperature, and 600 W ultrasound power. Under these conditions, the Trolox equivalent antioxidant capacity (TEAC) value of the extracts was 1074.61 ± 32.56 µmol Trolox/g dry weight (DW). Compared with conventional maceration (723.27 ± 11.61 µmol Trolox/g DW) and Soxhlet extraction methods (518.37 ± 23.23 µmol Trolox/g DW), the UAE method improved the extraction efficiency, in a shorter period of time. In addition, epicatechin gallate, epicatechin, rutin, epigallocatechin, protocatechuic acid, chlorogenic acid, and quercetin, were identified and quantified in the fruit extracts of Melastoma sanguineum Sims by UPLC-MS/MS.

HBsAg and HBeAg in the prediction of a clinical response to peginterferon α-2b therapy in Chinese HBeAg-positive patients.

BACKGROUND: This study aimed to evaluate the predictive values of hepatitis B e antigen (HBeAg) and hepatitis B surface antigen (HBsAg) levels in 171 Chinese patients with chronic hepatitis B who received a 48-week course of pegylated interferon alfa-2b therapy at 1.5 mcg/kg. METHODS: HBsAg, HBeAg, and hepatitis B virus (HBV) DNA levels were measured at baseline and weeks 12, 24, 48, and 72. Clinical responses were defined as a combined response (CR, HBeAg seroconversion [sustained response, SR] combined with HBV DNA level <2,000 IU/mL at week 72). The positive predictive value and negative predictive value were calculated for HBsAg alone and/or combined with HBeAg and HBV DNA at weeks 12 and 24. RESULTS: Of 171 patients included, 58 (33.9 %) achieved a SR. Of patients who achieved a SR, 33 (56.9 %) achieved a CR. Totally 19.3 % (33/171) patients achieved CR and 80.7 % (138/171) patients did not. Patients with HBsAg <1500 IU/mL at week 12 had a 47.4 % chance of achieving an off-treatment SR and patients with a HBsAg decrease >1.5 logIU/mL at week 12 had a 54.5 % chance. Patients with HBsAg >20,000 IU/mL at weeks 12 and 24 had a 93.8 and 100.0 % chance, respectively, of not achieving a CR. An HBsAg level or changes at weeks 12 and 24, combined with HBeAg or HBV DNA, increased the chance for a SR and CR. CONCLUSIONS: On-treatment HBsAg quantification, alone or in combination with HBeAg or HBV DNA, predicted off-treatment SR and CR after 48 weeks of PEG-IFNα-2b therapy, and thus, may guide clinicians in making a therapeutic decision to continue or terminate the therapy.

Multidrug resistance protein 4 is a critical protein associated with the antiviral efficacy of nucleos(t)ide analogues.

BACKGROUND & AIMS: Multidrug resistance protein 4 (MRP4) has been associated with nucleos(t)ide analogue (NA) antiretroviral therapy failure, though is unclear if MRP4 is also correlated with the failure of anti-hepatitis B virus (HBV) therapy. METHODS: Multidrug resistance protein 4 expression in human peripheral blood mononuclear cells (PBMCs), liver tissues and human hepatoma cell lines was detected by real-time polymerase chain reaction (PCR), western blotting and immunohistochemistry assays. Supernatant and intracellular HBV DNA levels of MRP4-overexpressing or silenced HepG2.4D14 (wild-type) and HepG2.A64 (entecavir-resistant mutant) cells were measured by quantitative PCR. NA concentrations and HBV mutational analysis were assessed by liquid chromatography/mass spectrometry assays and DNA sequencing. Multivariate analysis was used to assess predictive factors for treatment failure. RESULTS: High expression of MRP4 was found in hepatoma cell lines and PBMCs, and up- or down-regulation of MRP4 expression altered the susceptibility of cells to NAs. MRP inhibitors increased NA intracellular accumulation and decreased extracellular levels. Moreover, MRP4 expression in PBMCs was correlated with that in paired liver tissues. Furthermore, multivariate analysis showed MRP4 mRNA expression to be an independent predictor of NA treatment failure. CONCLUSIONS: Multidrug resistance protein 4 is a critical protein associated with the antiviral efficacy of NAs, and combination therapy of NA and MRP inhibitors could reduce the dosage for long-term NA use. This is the first report to demonstrate that MRP4 expression is an important factor predicting treatment failure in chronic hepatitis B patients and will provide a potential therapeutic target against HBV.