Hepatitis B virus X protein-mediated upregulation of miR-221 activates the CXCL12-CXCR4 axis to promote NKT cells in HBVrelated hepatocellular carcinoma

Both hepatitis B virus X protein(HBx)and microRNA-221(miR-221)have been implicated in the development of hepatitis B virus(HBV)-related hepatocellular carcinoma(HCC).The present study demonstrates that HBx promotes HCC cell proliferation via the C-X-C motif chemokine ligand 12-C-X-C chemokine receptor type 4(CXCL12-CXCR4)axis.We predict that HBx/miR-221-mediated CXCL12/CXCR4 signaling induces NKT cells to promote HBV-related HCC.Methods:After miR-221 mimic,miR-221 mimic negative control,miR-221 inhibitor,miR-221 inhibitor negative control were transfected into cells,the expression of CXCL12 and miR-221 was detected by qPCR and western blot.Then we constructed a stable HBV-HCC cell line.HBV-HCC cells were injected into the nude mice,thus a HBV-HCC mouse model was constructed.Q-PCR and western blot were used to detect the expression of HBx,miR-221,CXCL12 and CXCR4 in tumor tissues.The expression of CXCL12 was detected by immunohistochemistry,and the expression of CXCR4,CD3 and CD56 was detected by immunofluorescence.The levels of CXCL12,IL-2 and TNF-αin serum of mice were detected by ELISA.Sixty-one patients with HBV-related HCC,61 patients with HBV-related cirrhosis,61 patients with chronic hepatitis B(CHB)and 30 healthy people were enrolled.CXCL12,cytokine levels,and clinicopathological parameters were tested.Results:Hepatitis B virus X protein upregulates the expression of miR-221 and CXCL12 in lentivirus(LV5)-HBx-transfected HepG2 cells.HBx protein promotes HepG2 cell proliferation in vitro.HBx protein promoted tumor growth via the miR-221/CXCL12/CXCR4 pathway in a mouse tumor model.HBx protein upregulated natural killer T cell expression via the CXCR4/CXCL12 pathway to promote tumor growth.The data demonstrated a positive correlation between CXCL12 concentration with Cre levels and Child-Pugh scores.CXCL12 had an inferior diagnostic efficiency compared to IL-2 and IL-6 for HBV-related HCC.Conclusions:We present evidence that HBx/miR-221-mediated CXCL12/CXCR4 signaling induces NKT cells to promote HBV-related HCC.

Detection of hyper-conserved regions in hepatitis B virus X gene potentially useful for gene therapy

AIM To detect hyper-conserved regions in the hepatitis B virus(HBV) X gene(HBX) 5' region that could be candidates for gene therapy.METHODS The study included 27 chronic hepatitis B treatmentnaive patients in various clinical stages(from chronic infection to cirrhosis and hepatocellular carcinoma, both HBeA g-negative and HBeA g-positive), and infected with HBV genotypes A-F and H. In a serum sample from each patient with viremia > 3.5 log IU/m L, the HBX 5' end region [nucleotide(nt) 1255-1611] was PCRamplified and submitted to next-generation sequencing(NGS). We assessed genotype variants by phylogenetic analysis, and evaluated conservation of this region by calculating the information content of each nucleotide position in a multiple alignment of all unique sequences(haplotypes) obtained by NGS. Conservation at the HBx protein amino acid(aa) level was also analyzed.RESULTS NGS yielded 1333069 sequences from the 27 samples, with a median of 4578 sequences/sample(2487-9279, IQR 2817). In 14/27 patients(51.8%), phylogenetic analysis of viral nucleotide haplotypes showed a complex mixture of genotypic variants. Analysis of the information content in the haplotype multiple alignments detected 2 hyper-conserved nucleotide regions, one in the HBX upstream non-coding region(nt 1255-1286) and the other in the 5' end coding region(nt 1519-1603). This last region coded for a conserved amino acid region(aa 63-76) that partially overlaps a Kunitz-like domain.CONCLUSION Two hyper-conserved regions detected in the HBX 5' end may be of value for targeted gene therapy, regardless of the patients' clinical stage or HBV genotype.

Clinical utility of complex mutations in the core promoter and proximal precore regions of the hepatitis B virus genome

The core promoter and proximal precore regions are the most complex portions of the hepatitis B virus(HBV) genome. These regions cooperatively regulate viral replication and differentially regulate the synthesis of the viral proteins E,core,and X. Multiple mutations in these regions are associated with the persistency of viral infection and the development of cirrhosis and hepatocellular carcinoma(HCC). In South Korea,nearlyall HBVs are classified as HBV genotype C2; the majority of these viruses have the basal core promoter double mutation,a precore stop mutation,or both. These mutations may play a role in the alteration of viral and clinical features,and abundant and complex mutations are particularly prevalent in the core promoter and proximal precore regions. We previously demonstrated that the accumulation of ≥ 6 mutations at eight key nucleotides located in these regions(G1613A,C1653 T,T1753 V,A1762 T,G1764 A,A1846 T,G1896 A,and G1899A) is a useful marker to predict the development of HCC regardless of advanced liver disease. In addition,certain mutation combinations were predominant in cases with ≥ 4 mutations. In cases with ≤ 5 mutations,a low Hepatitis B e antigen titer(< 35 signal to noise ratio) was indicative of HCC risk. Viral mutation data of the single HBV genotype C2 suggest that the combined effect of the number and pattern of mutations in the core promoter and proximal precore regions is helpful in predicting HCC risk.

Characterization of hepatitis B virus X gene quasispecies complexity in mono-infection and hepatitis delta virus superinfection

Hepatitis delta virus(HDV) seems to strongly suppress hepatitis B virus(HBV)replication, although little is known about the mechanism of this interaction. Both these viruses show a dynamic distribution of mutants, resulting in viral quasispecies. Next-generation sequencing is a viable approach for analyzing the composition of these mutant spectra. As the regulatory hepatitis B X protein(HBx) is essential for HBV replication, determination of HBV X gene(HBX)quasispecies complexity in HBV/HDV infection compared to HBV monoinfection may provide information on the interactions between these two viruses.AIM To compare HBV quasispecies complexity in the HBX 5' region between chronic hepatitis delta(CHD) and chronic HBV mono-infected patients.METHODS Twenty-four untreated patients were included: 7/24(29.2%) with HBeAgnegative chronic HBV infection(CI, previously termed inactive carriers), 8/24(33.3%) with HBeAg-negative chronic hepatitis B(CHB) and 9/24(37.5%) with CHD. A serum sample from each patient was first tested for HBV DNA levels.The HBX 5' region [nucleotides(nt) 1255-1611] was then PCR-amplified for subsequent next-generation sequencing(MiSeq, Illumina, United States). HBV quasispecies complexity in the region analyzed was evaluated using incidencebased indices(number of haplotypes and number of mutations), abundancebased indices(Hill numbers of order 1 and 2), and functional indices(mutation frequency and nucleotide diversity). We also evaluated the pattern of nucleotide changes to investigate which of them could be the cause of the quasispecies complexity.RESULTS CHB patients showed higher median HBV-DNA levels [5.4 logIU/mL,interquartile range(IQR) 3.5-7.9] than CHD(3.4 logIU/mL, IQR 3-7.6)(P = n.s.)or CI(3.2 logIU/mL, IQR 2.3-3.5)(P < 0.01) patients. The incidence and abundance indices indicated that HBV quasispecies complexity was significantly greater in CI than CHB. A similar trend was observed in CHD patients, although only Hill numbers of order 2 showed statistically significant differences(CHB2.81, IQR 1.11-4.57 vs CHD 8.87, 6.56-11.18, P = 0.038). There were no significant differences in the functional indices, but CI and CHD patients also showed a trend towards greater complexity than CHB. No differences were found for any HBV quasispecies complexity indices between CHD and CI patients. G-to-A and C-to-T nucleotide changes, characteristic of APOBEC3 G, were higher in CHD and CI than in CHB in genotype A haplotypes, but not in genotype D. The proportion of nt G-to-A vs A-to-G changes and C-to-T vs T-to-C changes in genotype A and D haplotypes in CHD patients showed no significant differences. In CHB and CI the results of these comparisons were dependent on HBV genotype.CONCLUSION The lower-replication CHD and CI groups show a trend to higher quasispecies complexity than the higher-replication CHB group. The mechanisms associated with this greater complexity require elucidation.

Upreguiation of human telomerase reverse transcriptase mRNA expression by in vitro transfection of hepatitis B virus X gene into human hepatocarcinoma and cholangiocarcinoma cells

AIM： To study the changes of human telomerase reverse transcriptase （hTERT） mRNA expression in human hepatocarcinoma cell lines （HepG2） and cholangiocarcinoma cell lines （QBC939） after HBx gene transfection and to illustrate the significance of transcriptional regulation of hTERT gene by HBx gene in the carcinogenesis. METHODS： HepG2 and QBC939 cell lines were cultured and co-transfected with eukaryotic expression vector containing the HBx coding region and cloning vector containing enhanced green fluorescent protein （EGFP） coding sequence using lipid-mediated gene transduction technique. Thirty-six hours after transfection, EGFP expression in cells was used as the indicator of successful transfection. Flow cytometry was performed to determine the transfection efficiency. Cells were harvested and total RNA was extracted using TRIzol reagent. The expression of hTERT mRNA in HepG2 and QBC939 cell lines was assayed by reverse transcriptionpolymerase chain reaction. The expression of HBx protein in both cell lines was detected by immunocytochemical staining and Western blotting. RESULTS： Flow cytometry showed that the transfection efficiency was 46.4% in HepG2 cells and 29.6% in QBC939 cells for both HBx gene expression vector and blank vector. The expression of hTERT mRNA was meaningfully increased in HepG2 and QBC939 cell lines when transfected with HBx gene expression vector compared to those transfected with OPTI-MEM medium and blank vector. Immunocytochemical staining and Western blotting revealed HBx protein expression in HepG2 and QBC939 cells only when transfected with HBx gene. CONCLUSION： HBx gene transfection can upregulate the transcriptional expression of hTERT mRNA. The transactivation of hTERT gene by HBx gene is a newfound mechanism for pathogenesis of hepatocarcinomas and cholangiocarcinomas after HBV infection. 2005 The WJG Press and Elsevier Inc. All rights reserved

Inhibition of apoptosis by oncogenic hepatitis B virus X protein: Implications for the treatment of hepatocellular carcinoma

Hepatitis B virus X protein(HBx) plays an important role in the development of hepatocellular carcinoma(HCC). In addition, hepatoma upregulated protein(HURP) is a cellular oncogene that is upregulated in a majority of HCC cases. We highlight here recent findings demonstrating a link between HBx, HURP and anti-apoptosis effects observed in cisplatin-treated HCC cells. We observed that Hep3B cells overexpressing HBx display increased HURP mRNA and protein levels, and show resistance to cisplatin-induced apoptosis. Knockdown of HURP in HBx-expressing cells reverses this effect, and sensitizes cells to cisplatin. The anti-apoptotic effect of HBx requires activation of the p38/MAPK pathway as well as expression of SATB1, survivin and HURP. Furthermore, silencing of HURP using short-hairpin RNA promotes accumulation of p53 and reduces cell proliferation in SK-Hep-1 cells(p53^(+/–)), whereas these effects are not observed in p53-mutant Mahlavu cells. Similarly, HURP silencing does not affect the proliferation of H1299 lung carcinoma cells or Hep3 B HCC cells which lack p53. Silencing of HURP sensitizes SK-Hep-1 cells to cisplatin. While HURP overexpression promotes p53 ubiquitination and degradation by the proteasome, HURP silencing reverses these effects. Inoculation of SK-Hep-1 cancer cells in which HURP has been silenced produces smaller tumors than control in nude mice. Besides, gankyrin, a positive regulator of the E3 ubiquitin ligase MDM2, is upregulated following HURP expression, and silencing of gankyrin reduces HURP-mediated downregulation of p53. In addition, we observed a positive correlation between HURP and gankyrin protein levels in HCC patients(r^2 = 0.778; n = 9). These findings suggest a role for the viral protein HBx and the host protein HURP in preventing p53-mediated apoptosis during cancer progression and establishment of chemoresistance.

Expression of B7-H4 and hepatitis B virus X in hepatitis B virus-related hepatocellular carcinoma

AIM: To investigate the expression and clinical significance of B7-H4 and hepatitis B virus X(HBx) protein in hepatitis B virus-related hepatocellular carcinoma(HBV-HCC).METHODS: The expression of B7-H4 in the human HCC cell lines Hep G2 and Hep G2.2.15 were detected by western blot, flow cytometry, and immunofluorescence. The expression of B7-H4 and HBx in 83 HBV-HCC was detected by immunohistochemistry, and the relationship with clinicopathological features was analyzed. Paraffin sections were generated from 83 HBV-HCC patients(22 females and 61 males) enrolled in this study. The age of these patients ranged from 35 to 77 years, with an average of 52.5 ± 11.3 years. All experiments were approved by the Ethics Committees of the Second Affiliated Hospital, Zhejiang University School of Medicine.RESULTS: B7-H4 was significantly upregulated in Hep G2.2.15 cells compared to Hep G2 cells. Specifically, the protein expression of B7-H4 in the lysates of Hep G2 cells was more than that in Hep G2.2.15 cells. In addition, HBx was expressed only in Hep G2.2.15 cells. Similar data were obtained by flow cytometry. The positive rates of B7-H4 and HBx in the tissues of 83 HBV-HCC patients were 68.67%(57/83) and 59.04%(49/83), respectively. The expression of HBx was correlated with tumor node metastases(TNM) stage, and the expression of B7-H4 was positively correlated with HBx(rs = 0.388; p < 0.01). The expression level of B7-H4 in HBx-positive HBV-HCC tissues was substantially higher than that in HBx-negative HBV-HCC tissues. The expression level of B7H4 was negatively related to tumor TNM stage.CONCLUSION: Higher expression of HBx and B7-H4 was correlated with tumor progression of HBV-HCC, suggesting that B7-H4 may be involved in facilitating HBV-related hepatocarcinogenesis.

Hepatitis B virus X protein promotes liver cell proliferation via a positive cascade loop involving arachidonic acid metabolism and p-ERK1/2

Hepatitis B virus X protein （HBx） plays a crucial role in the development of hepatocellular carcinoma. Here, we sought to identify the mechanisms by which HBx mediates liver cell proliferation. We found that HBx upregulated the levels of cyclooxygenase-2 （COX-2）, 5-1ipoxygenase （5-LOX） and phosphorylated extracellular signal-regulated protein kinases 1/2 （p-ERK1/2） in liver cells. HBx-induced p-ERK1/2 was abolished by inhibition of Gi/o proteins, COX or LOX. In addition, HBx increased the amounts of prostaglandin E2 （PGE2） and leukotriene B4 （LTB4） released from cell lines derived from hepatocytes. Moreover, these released arachidonic acid metabolites were able to activate ERK1/2. Interestingly, activated ERK1/2 could upregulate the expression of COX-2 and 5-LOX in a positive feedback manner. In conclusion, HBx enhances and maintains liver cell proliferation via a positive feedback loop involving COX-2, 5-LOX, released arachidonic acid metabolites, Gi/o proteins and p-ERK1/2.

Possible mechanism for hepatitis B virus X gene to induce apoptosis of hepatocytes

AIM： To investigate the possible mechanism for HBV X gene to induce apoptosis of hepatocyte HL-7702 cells.METHODS： HBV X gene eukaryon expression vector pcDNA3-X was established and transfected into HL-7702 cells by lipid-mediated transfection, including transient and stable transfection. Positive clones were screened by incubating in the selective medium with 600 μg/mL G418 and named HL-7702/HBV-encoded X protein （HBx） cells. The expressions of Fas/FasL, Bax/Bcl-2, and c-myc mRNA were measured by semi-quantitative RT-PCR in HL-7702/HBx and control group, respectively.RESULTS： RT-PCR analysis confirmed that HBV X gene was transfected into HL-7702 cells successfully. By semiquantitative RT-PCR analysis, Bax and c-myc mRNA levels in HL-7702/HBx cells of transient transfection were significantly higher than those in control, FasL and c-myc mRNA levels in HL-7702/HBx cells of stable transfection were significantly higher than those in control, whereas the Bcl-2 mRNA levels in HL-7702/HBx cells of transient and stable transfection were significantly lower than thosein control.CONCLUSION： HBV X gene may promote the apoptosis of hepatocytes by regulating the expressions of Fas/FasL, Bax/Bcl-2, and c-myc gene in a dose-dependent manner.

Hepatitis B virus X protein induces hepatic stem cell-like features in hepatocellular carcinoma by activating KDM5B

To determine the role of hepatitis B virus X protein (HBx), HBx in regulating hepatic progenitor cell (HPC)-like features in hepatocellular carcinoma (HCC) and the underlying molecular mechanisms.METHODSWe used a retrovirus vector to introduce wild type HBx or empty vector into HepG2 cells. We then used these cells to analyze cell proliferation, senescence, transformation, and stem-like features. Gene expression profiling was carried out on Affymetrix GeneChip Human U133A2.0 ver.2 arrays according to the manufacturer’s protocol. Unsupervised hierarchical clustering analysis and Class Comparison analysis were performed by BRB-Array Tools software Version 4.2.2. A total of 238 hepatitis B virus (HBV)-related HCC patients’ array data were used for analyzing clinical features.RESULTSThe histone demethylase KDM5B was significantly highly expressed in HBV-related HCC cases (P < 0.01). In HBV proteins, only HBx up-regulated KDM5B by activating c-myc. Hepatic stem cell (HpSC) markers (EpCAM, AFP, PROM1, and NANOG) were significantly highly expressed in KDM5B-high HCC cases (P < 0.01). KDM5B played an important role in maintaining HpSC-like features and was associated with a poor prognosis. Moreover, inhibition of KDM5B suppressed spheroid formation and cell invasion in vitro.CONCLUSIONHBx activates the histone demethylase KDM5B and induces HPC-like features in HCC. Histone demethylases KDM5B may be an important therapeutic target against HBV-related HCC cases.

Biological impact of hepatitis B virus X-hepatitis C virus core fusion gene on human hepatocytes

AIM： To investigate the biological impact of hepatitis B virus X- hepatitis C virus core （HBV X-HCV C） fusion gene on hepatoma cells.METHODS： The recombinant adenoviruses Ad- XC, Ad-X and Ad-C expressing HBV X-HCV C fusion gene, HBVX gene and HCV C gene were constructed, respectively. Hepatoma cells were infected with different recombinant adenoviruses. MTT, colony- forming experiment, FCM, TUNEL assay were performed to observe the biological impact of the HBV X-HCV C fusion aene on liver cells.RESULTS： MTT showed that the Ad-XC group cells grew faster than the other group cells. Colony-forming experiment showed that the colony-forming rate for the Ad-XC group cells was significantly higher than that for the other group cells. FCM analysis showed that Ad-XC/Ad-X/Ad-C infection enhanced the progression of G1→S phase in the HepG2 cell cycle. The apoptosis index of the Ad-XC, Ad-X, Ad-C group cells was significantly lower than that of the AdO and control group cells. Semi-quantitative RT-PCR showed that the expression level of c-myc was the highest in Ad- XC infected cells. Tumor formation was found at the injected site of mice inoculated with Ad-XC-infected LO2 cells, but not in control mice.CONCLUSION： Ad-XC, Ad-X and Ad-C facilitate the proliferation activity of HepG2 cells and inhibit their apoptosis in vitro. The effect of Ad-XC is significantly stronger than that of Ad-X and Ad-C. Up-regulation of c-myc may be one of the mechanisms underlying the synergism of HBVX and HCV C genes on hepatocarcinogenesis in athymic nude mice.

Biological impacts of "hot-spot" mutations of hepatitis B virus X proteins are genotype B and C differentiated

AIM: To investigate the biological impacts of 'hot-spot'mutations on genotype B and C HBV X proteins (HBx).METHODS: Five types of'hot-spot' mutations of genotype B or C HBV X genes, which sequentially lead to the amino acid substitutions of HBx as I127T, F132Y, K130M+V131I,I127T+K130M+V131I, or K130M+V131I+F132Y, respectively,were generated by means of site-directed mutagenesis.To evaluate the anti-proliferative effects, HBx or related mutants' expression vectors were transfected separately to the Chang cells by lipofectamine, and the cells were cultured in hygromycin selective medium for 14 d, drug-resistant colonies were fixed with cold methanol, stained with Giemsa dyes and scored (increase of the colonies indicated the reduction of the anti-proliferation activity,and vice versa). Different types of HBx expression vectors were co-transfected separately with the reporter plasmid pCMVβ to Chang cells, which were lysed 48 h post-transfection and the intra-cellular β-galactosidase activities were monitored (increase of the β-galactosidase activities indicated the reduction of the transactivation activity, and vice versa). All data obtained were calculated by paired-samples t-test.RESULTS: As compared to standard genotype B HBx,mutants of I127T and I127T+K130M+V131I showed higher transactivation and anti-proliferative activities, while the mutants of F132Y, K130M+V131I, and K130M+V131I+F132Y showed lower activities. As compared to standard genotype C HBx, I127T mutant showed higher transactivation activity, while the other four types of mutants showed no differences. With regard to anti-proliferative activity,compared to standard genotype C HBx, F132Y and K130M+V131I mutants showed lower activities, and K130M+V131I +F132Y mutant, on the other hand, showed higher activity,while the mutants of I127T and I127T+K130M+V131I showed no differences.CONCLUSION: 'Hot-spot' mutations affect the antiproliferation and transactivation activities of genotype B and/or C HBx, and the biological impacts of most 'hot-spot' mutations on HBx are genotype B and C differentiated.

A mutation of the start codon in the X region of hepatitis B virus DNA in a patient with non-B,non-C chronic hepatitis

There are cases of hepatitis involving occult hepatitis B virus(HBV)infection in which,even though the HB surface antigen(HBsAg)is negative,HBV-DNA is detected by a polymerase chain reaction(PCR).We con-ducted a sequence analysis of the entire HBV region in a case of non-B non-C chronic hepatitis in a 46-yearold female.A diagnosis of non-B non-C chronic hepatitis was made.Although HBV markers,such as HBs antibody(anti-HBs),anti-HBc,HBeAg and anti-HBe,were negative,HBV-DNA was positive.Nested PCR was performed to amplify the precore region of HBV-DNA and all remaining regions by long nested PCR.Sequence analysis of the two obtained bands was conducted by direct sequencing.Compared with the control strains,the ATG(Methionine)start codon in the X region had mut ated to GTG(Valine).It is assumed that a mutation at the start codon in the X region may be the reason why HBV markers are negative in some cases of hepatitis that involve occult HBV infection.

Development of Fok-I based nested polymerase chain reaction-restriction fragment length polymorphism analysis for detection of hepatitis B virus X region V5M mutation

AIM: To develop a Fok-I nested polymerase chain reaction(PCR)-restriction fragment length polymorphism analysis(PRA) method for the detection of hepatitis B virus X region(HBx) V5 M mutation.METHODS: Nested PCR was applied into DNAs from 198 chronic patients at 2 different stages [121 patients with hepatocellular carcinoma(HCC) and 77 carrier patients]. To identify V5 M mutants, digestion of nested PCR amplicons by the restriction enzyme Fok-I(GGA TGN9↓) was done. For size comparison, the enzymetreated products were analyzed by electrophoresis on 2.5% agarose gels, stained with ethidium bromide, and visualized on a UV transilluminator.RESULTS: The assay enabled the identification of 69 patients(sensitivity of 34.8%; 46 HCC patients and 23 carrier patients). Our data also showed that V5 M prevalence in HCC patients was significantly higher than in carrier patients(47.8%, 22/46 patients vs 0%, 0/23 patients, P < 0.001), suggesting that HBx Ag V5 M mutation may play a pivotal role in HCC generation in chronic patients with genotype C infections.CONCLUSION: The Fok-I nested PRA developed in this study is a reliable and cost-effective method to detect HBx Ag V5 M mutation in chronic patients with genotype C2 infection.

The influence of hepatitis B virus X protein on the clock genes in liver cells and its significance

Objective： The aim of this study was to investigate the influence of hepatitis B virus X protein （HBx） on the clock genes in LO2 cells and its significance. Methods： A cell line LO2-HBx, Stably transfected with HBx gene, was established. The levels of mRNA and protein expression of CLOCK and BMAL1 were detected by real-time PCR and western blot. Resuits： The expression of CLOCK mRNA and protein were increased in cell line LO2-HBx （P 〈 0.05）, while the expression of BMAL1 mRNA and protein were decreased in cell line LO2-HBx （P 〈 0.05）. Conclusion： The expressions of core clock gene CLOCK and BMAL1 have been changed by HBx, which breaks down the previous circadian rhythm of liver cells. This maybe one of the reasons leads to the formation of liver cancer.

Interferon-alpha restrains growth and invasive potential of hepatocellular carcinoma induced by hepatitis B virus X protein

AIM: To investigate the effects of interferon-alpha (IFN-α) to restrain the growth and invasive potential of hepatocellular carcinoma (HCC) induced by hepatitis B virus (HBV) X protein. METHODS: The pcDNA3.1-HBx plasmid was transfected into Chang cells by Lipofectamine in vitro, and Chang/HBx was co-cultured with IFN-α. Cell survival growth curve and clonogenicity assay were used to test the growth potential of Chang/pcDNA3.1, Chang/HBx and IFN-α-Chang/HBx in vitro. Growth assay in nude mice was used to detect the growth potential of Chang/ pcDNA3.1, Chang/HBx and IFN-α-Chang/HBx in vivo. Wound healing and transwell migration assays were used to detect the invasive ability of Chang/pcDNA3.1, Chang/HBx and IFN-α-Chang/HBx. RESULTS: Compared with CCL13 cells transfected with pcDNA3.1, CCL13 with stable expression of hepatitis B virus X protein showed the characteristics of malignant cells with high capability of growth and invasion by detecting their growth curves, colony forming efficiency, wound healing , transwell migration assays and growth assays in nude mice. Its capability of growth and invasion could be controlled by IFN-α. CONCLUSION: IFN-α can restrain the growth and invasive potential of HCC cells induced by HBx protein, which has provided an experimental basis for IFN-α therapy of HCC.

X region mutations of hepatitis B virus related to clinical severity

Chronic hepatitis B virus (HBV) infection remains a major health problem, with more than 240 million people chronically infected worldwide and potentially 650000 deaths per year due to advanced liver diseases including liver cirrhosis and hepatocellular carcinoma (HCC). HBV-X protein (HBx) contributes to the biology and pathogenesis of HBV via stimulating virus replication or altering host gene expression related to HCC. The HBV X region contains only 465 bp encoding the 16.5 kDa HBx protein, which also contains several critical cis-elements such as enhancer II, the core promoter and the microRNA-binding region. Thus, mutations in this region may affect not only the HBx open reading frame but also the overlapped cis-elements. Recently, several types of HBx mutations significantly associated with clinical severity have been described, although the functional mechanism in most of these cases remains unsolved. This review article will mainly focus on the HBx mutations proven to be significantly related to clinical severity via epidemiological studies.

Hepatitis B virus X protein accelerates the development of hepatoma

The chronic infection of hepatitis B virus(HBV) is closely related to the occurrence and development of hepatocellular carcinoma(HCC). Accumulated evidence has shown that HBV X protein(HBx protein) is a multifunctional regulator with a crucial role in hepatocarcinogenesis. However, information on the mechanism by which HBV induces HCC is lacking. This review focuses on the pathological functions of HBx in HBV-induced hepatocarcinogenesis. As a transactivator, HBx can modulate nuclear factor kappa-light-chain-enhancer of activated B cells(NF-κB) and transcription factor AP-2. Moreover, HBx can affect regulatory non-coding RNAs(ncRNAs) including microRNAs and long ncRNAs(lncRNAs), such as miRNA-205 and highly upregulated in liver cancer(HULC), respectively. HBx is also involved in epigenetic modification, including methylation and acetylation. HBx interacts with various signal-transduction pathways, such as protein kinase B/Akt, Wnt/β-catenin, signal transducer and activator of transcription, and NF-κB pathways. Moreover, HBx affects cellular fate by shifting the balance toward cell survival. HBx may lead to the loss of apoptotic functions or directly contributes to oncogenesis by achieving transforming functions, which induce hepatocarcinogenesis. Additionally, HBx can modulate apoptosis and immune response by direct or indirect interaction with host factors. We conclude that HBx hastens the development of hepatoma.

Hepatitis B virus X protein regulates the mEZH2 promoter via the E2F1-binding site in AML12 cells

Histone lysine methyltransferase EZH2 has been reported to be frequently overexpressed in hepatocellular carcinoma(HCC) tissues and associated with hepatocarcinogenesis.However,the exact mechanism of EZH2 up-regulation in HCC has not been determined.In this study,we used murine hepatocyte AML12 cells to investigate the role of hepatitis B virus X protein(HBx) in regulating the expression of mEZH2.Western blot analysis demonstrated that the expression level of mEZH2 protein in AML12 cells was up-regulated by HBx in a dose-dependent manner.To further investigate the mechanism of mEZH2 overexpression,the 2500 bp regulatory sequence upstream from the first exon of the mEZH2 gene was amplified from AML12 genomic DNA and constructed into a luciferase reporter plasmid.The luciferase activity of the mEZH2 promoter significantly increased in AML12 cells co-transfected with HBx plasmid,and deleting the-486/-214 promoter region decreased HBx-induced mEZH2 promoter activation by nearly 50%.The-486/-214 region was then analyzed in the TRANSFAC 6.0 database and a typical E2F1-binding site was found.Mutation of this E2F1-binding site or knockdown of E2F1 expression by RNAi led to a dramatic decrease in HBx-induced activation of the mEZH2 promoter and mEZH2 overexpression in AML12 cells.These results provide evidence that HBx up-regulates mEZH2 expression by transactivating the mEZH2 promoter through E2F1 transcription factor,thereby providing new epigenetic evidence for the carcinogenic effect of HBx.

Expression of Cytokines in Mouse Hepatitis B Virus X Gene-transfected Model

The expression profile in the mouse hepatitis B virus X （HBx）-transfected model was investigated in order to lay a foundation for further study on the implication of cytokines expression in hepa- titis B virus （HBV） infection. Hydrodynamic injection method via the tail vein was used to establish the animal HBx-transfected model. By using microassay, the differential expression of gene in each group was analyzed, which was further confirmed by using real-time PCR and semi-quantitative PCR. Most of chemokine genes such as Cc12, Cc15, Cc19, MIG and IP-10 were up-regulated in the HBx-transfected mouse model versus the control mice, which was coincided with the microarray results. Western blotting and immunohistochemistry were applied to detect the expression of MIG and IP-10 in the liver tissues. Simultaneously, ELISA was adopted to measure the content of IFN-y in the liver tissues. DNA mi- croassay revealed that the expression of 611 genes changed in HBx-transfected mice as compared with that in pCMV-tag2B-transfected mice, and most of the screened chemokines were up-regulated （includ- ing MIG and IP-10）. Additionally, IFN-y protein levels were increased by 20.7% （P〈0.05） in pCMV-tag2B-HBx-transfected mice as compared with the untreated mice. IFN-7 protein levels were reduced by 53.9% （P〈0.05） in pCMV-tag2B-transfected mice as compared with the untreated mice, which was consistent with the up-regulation of MIG and IP-10. It was suggested HBx transfection could induce the expression of MIG and IP-10 in the liver tissues, which might play the roles in HBV-related liver immunity and cytokines-mediated antiviral effect.