Expression of nuclear factor-κB in hepatocellular carcinoma and its relation with the X protein of hepatitis B virus

Role of AHR, NF-kB and CYP1A1 crosstalk with the X protein of Hepatitis B virus in hepatocellular carcinoma cells

In this study, it was aimed to elucidate the interaction between aryl hydrocarbon receptor (AHR), nuclear factor-kappa B (NF-kB), and cytochrome P4501A1 (CYP1A1) with hepatitis B virus X protein (HBX) in a human liver cancer cell line (HepG2) transfected with HBX. First, AHR, NF-kB, and CYP1A1 genes were cloned into the appropriate region of the CheckMate mammalian two-hybrid recipient plasmids using a flexi vector system. Renilla and firefly luciferases were quantified using the dual-luciferase reporter assay system to measure the interactions. Secondly, transient transfections of CYP1A1 and NF-kB (RelA) were performed into HBX-positive and HBX-negative HepG2 cells. The mRNA expression of CYP1A1 and NF-kB genes were confirmed with RT-PCR, and cell viability was measured by WST-1. Further verification was assessed by measuring the activity and protein level of CYP1A1. Additionally, CYP1A1/HBX protein-protein interactions were performed with co-immunoprecipitation, which demonstrated no interaction. These results have clearly shown that the NF-kB and AHR genes interact with HBX without involving CYP1A1 and HBX protein-protein interactions. The present study confirms that AHR and NF-kB interaction plays a role in the HBV mechanism mediated via HBX and coordinating the carcinogenic or inflammatory responses; still, the CYP1A1 gene has no effect on this interaction.

Hepatitis B x (HBx) as a Component of a Functional Cure for Chronic Hepatitis B

Patients who are carriers of the hepatitis B virus (HBV) are at high risk of chronic liver disease (CLD) which proceeds from hepatitis, to fibrosis, cirrhosis and to hepatocellular carcinoma (HCC). The hepatitis B-encoded X antigen, HBx, promotes virus gene expression and replication, protects infected hepatocytes from immunological destruction, and promotes the development of CLD and HCC. For virus replication, HBx regulates covalently closed circular (ccc) HBV DNA transcription, while for CLD, HBx triggers cellular oxidative stress, in part, by triggering mitochondrial damage that stimulates innate immunity. Constitutive activation of NF-κB by HBx transcriptionally activates pro-inflammatory genes, resulting in hepatocellular destruction, regeneration, and increased integration of the HBx gene into the host genome. NF-κB is also hepatoprotective, which sustains the survival of infected cells. Multiple therapeutic approaches include direct-acting anti-viral compounds and immune-stimulating drugs, but functional cures were not achieved, in part, because none were yet devised to target HBx. In addition, many patients with cirrhosis or HCC have little or no virus replication, but continue to express HBx from integrated templates, suggesting that HBx contributes to the pathogenesis of CLD. Blocking HBx activity will, therefore, impact multiple aspects of the host–virus relationship that are relevant to achieving a functional cure.

Interplay Between Non-Canonical NF-κB Signaling and Hepatitis B Virus Infection

The non-canonical nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway is an important component of NF-κB transcription complex. Activation of this pathway mediates the development and function of host immune system involved in inflammation and viral infection. During hepatitis B virus (HBV) infection, there is a complex interaction between infected hepatocytes and the immune cells, which can hinder antiviral immune responses and is associated with pathological changes in liver tissue. Consistently, the host immune system is closely related to the severity of liver damage and the level of viral replication. Previous studies indicated that the non-canonical NF-κB signaling pathway was affected by HBV and might play an important regulatory role in the antiviral immunity. Therefore, systematically elucidating the interplay between HBV and non-canonical NF-κB signaling will contribute the discovery of more potential therapeutic targets and novel drugs to treat HBV infection.

Short chain fatty acids delay the development of hepatocellular carcinoma in HBx transgenic mice

Chronic infection with hepatitis B virus (HBV) is a major risk factor for the development of hepatocellular carcinoma (HCC). The HBV encoded oncoprotein, HBx, alters the expression of host genes and the activity of multiple signal transduction pathways that contribute to the pathogenesis of HCC by multiple mechanisms independent of HBV replication. However, it is not clear which pathways are the most relevant therapeutic targets in hepatocarcinogenesis. Short chain fatty acids (SCFAs) have strong anti-inflammatory and anti-neoplastic properties, suggesting that they may block the progression of chronic liver disease (CLD) to HCC, thereby identifying the mechanisms relevant to HCC development. This hypothesis was tested in HBx transgenic (HBxTg) mice fed SCFAs. Groups of HBxTg mice were fed with SCFAs or vehicle from 6 to 9 months of age and then assessed for dysplasia, and from 9 to 12 months of age and then assessed for HCC. Livers from 12 month old mice were then analyzed for changes in gene expression by mass spectrometry-based proteomics. SCFA-fed mice had significantly fewer dysplastic and HCC nodules compared to controls at 9 and 12 months, respectively. Pathway analysis of SCFA-fed mice showed down-regulation of signaling pathways altered by HBx in human CLD and HCC, including those involved in inflammation, phosphatidylinositol 3-kinase, epidermal growth factor, and Ras. SCFA treatment promoted increased expression of the tumor suppressor, disabled homolog 2 (DAB2). DAB2 depresses Ras pathway activity, which is constitutively activated by HBx. SCFAs also reduced cell viability in HBx-transfected cell lines in a dose-dependent manner while the viability of primary human hepatocytes was unaffected. These unique findings demonstrate that SCFAs delay the pathogenesis of CLD and development of HCC, and provide insight into some of the underlying mechanisms that are relevant to pathogenesis in that they are responsive to treatment.

Hepatitis B virus X protein promotes epithelial-mesenchymal transition and metastasis in hepatocellular carcinoma cell line HCCLM3 by targeting HMGA2

Chronic hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC), and HBV X protein (HBx) serves an essential role in the development of HCC. However, its mechanism remains to be elucidated. The aim of the present study was to investigate the role and mechanism of the HBx protein in the epithelial-mesenchymal transition (EMT) and metastasis of HCC. The HCCLM3 cell line was transfected with a HBx-expressing vector. The effects of HBx overexpression on proliferation, migration, invasion and EMT capacities of the HCCLM3 cell line were evaluated using MTT, migration and invasion assays, and western blotting, respectively. Furthermore, the impact of High mobility group AT-hook 2 (HMGA2) knockdown on HBx-mediated metastasis was investigated in the HCC cell line HCCLM3. The results demonstrated that HBx significantly upregulated HMGA2 expression, and enhanced the proliferation, EMT, invasion and migration in HCC cells. Furthermore, HMGA2 knockdown almost abolished HBx-induced EMT and metastasis in HCC. The results of the present study suggest that HBx promotes the proliferation, EMT, invasion and migration of HCC cells by targeting HMGA2. HMGB2 may serve as a potential therapeutic target for HBV-associated HCC.

Hepatitis B virus X protein increases the IL-1β-induced NF-κB activation via interaction with evolutionarily conserved signaling intermediate in Toll pathways (ECSIT)

Hepatitis B virus X protein (HBx) transactivates multiple transcription factors including nuclear factor-kappa B (NF-κB) that regulates inflammatory-related genes. However, the regulatory mechanism of HBx in NF-κB activation remains largely unknown. This study reports that HBx augments the interleukin-1β (IL-1β)-induced NF-κB activation via interaction with a Toll-like receptor (TLR) adapter protein, ECSIT (evolutionarily conserved signaling intermediate in Toll pathways). GST pull-down and co-immunoprecipitation analyses showed that HBx interacted with ECSIT. Deletion analysis of HBx in a CytoTrap two-hybrid system revealed that the interaction region of HBx for ECSIT was attributed to aa 51-80. Co-transfection of HBx and ECSIT in IL-1β-stimulated cells appeared to activate IKK and IκB signaling pathway as phosphorylation of both IKK α/β and IκBα was increased whereas knockdown of ECSIT or HBxΔ51-80 mutant attenuated the phosphorylation. As a consequence of IκBα degradation, NF-κB was activated as evidenced by increases in NF-κB transcriptional activity and the nuclear translocation of p65 and p50 that resulted in the induction of IL-10. In contrast, knockdown of ECSIT by siRNA or treatment with an NF-κB selective inhibitor (helenalin) abolished the NF-κB activation and IL-10 expression. We conclude that ECSIT appears to be a novel HBx-interacting signal molecule and their interaction is mechanistically important in IL-1β induction of NF-κB activation.

Inhibition of hepatitis B virus gene expression & replication by crude destruxins from Metarhizium anisopliae var. dcjhyium

BACKGROUND & OBJECTIVES

Destruxin A, destruxin B and destruxin E isolated from entomopathogenic fungus Metarhizium anisopliae showed a strong suppressive effect on the replication of hepatitis B virus (HBV) in human hepatoma cells. In this study, the anti-HBV effects of the crude destruxins extracted from M. anisopliae var. dcjhyium were detected both in vitro and in vivo.

METHODS

HepG2.2.15 cells were cultured to observe the inhibitory effects of the crude destruxins on the gene expression and replication of HBV by radioimmunoassay detection and real-time quantitative PCR. In vivo, duck HBV (DHBV)-infected ducks were treated with the crude destruxins at 2.0, 4.0, 6.0 μg/kg once a day for 15 days, DHBV DNA was examined by real-time quantitative PCR.

RESULTS

The crude destruxins suppressed the replication of HBV-DNA and the production of HBsAg and HBeAg with IC 50 of about 1.2 and 1.4 μg/ml. Transcript of viral mRNA was significantly suppressed by the crude destruxins in HepG2.2.15 cells. In vivo, the duck serum DHBV-DNA levels were markedly reduced in the group of the crude destruxins.

INTERPRETATION & CONCLUSIONS

The crude destruxins inhibited the gene expression and replication of HBV both in vitro and in vivo, and their anti-HBV effect was stronger than that with destruxin B. Our results indicate that the crude destruxins from M.anisopliae var. dcjhyium may be potential antivirus agents. Further studies need to be done to confirm these findings.

Hepatitis B virus X protein upregulates mTOR signaling through IKKβ to increase cell proliferation and VEGF production in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a major cause of cancer-related death in Southeast Asia, is frequently associated with hepatitis B virus (HBV) infection. HBV X protein (HBx), encoded by a viral non-structural gene, is a multifunctional regulator in HBV-associated tumor development. We investigated novel signaling pathways underlying HBx-induced liver tumorigenesis and found that the signaling pathway involving IκB kinase β (IKKβ), tuberous sclerosis complex 1 (TSC1), and mammalian target of rapamycin (mTOR) downstream effector S6 kinase (S6K1), was upregulated when HBx was overexpressed in hepatoma cells. HBx-induced S6K1 activation was reversed by IKKβ inhibitor Bay 11-7082 or silencing IKKβ expression using siRNA. HBx upregulated cell proliferation and vascular endothelial growth factor (VEGF) production, and these HBx-upregulated phenotypes were abolished by treatment with IKKβ inhibitor Bay 11-7082 or mTOR inhibitor rapamycin. The association of HBx-modulated IKKβ/mTOR/S6K1 signaling with liver tumorigenesis was verified in a HBx transgenic mouse model in which pIKKβ, pS6K1, and VEGF expression was found to be higher in cancerous than non-cancerous liver tissues. Furthermore, we also found that pIKKβ levels were strongly correlated with pTSC1 and pS6K1 levels in HBV-associated hepatoma tissue specimens taken from 95 patients, and that higher pIKKβ, pTSC1, and pS6K1 levels were correlated with a poor prognosis in these patients. Taken together, our findings demonstrate that HBx deregulates TSC1/mTOR signaling through IKKβ, which is crucially linked to HBV-associated HCC development.

Hepatitis B virus X protein upregulates mTOR signaling through IKKβ to increase cell proliferation and VEGF production in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a major cause of cancer-related death in Southeast Asia, is frequently associated with hepatitis B virus (HBV) infection. HBV X protein (HBx), encoded by a viral non-structural gene, is a multifunctional regulator in HBV-associated tumor development. We investigated novel signaling pathways underlying HBx-induced liver tumorigenesis and found that the signaling pathway involving IκB kinase β (IKKβ), tuberous sclerosis complex 1 (TSC1), and mammalian target of rapamycin (mTOR) downstream effector S6 kinase (S6K1), was upregulated when HBx was overexpressed in hepatoma cells. HBx-induced S6K1 activation was reversed by IKKβ inhibitor Bay 11-7082 or silencing IKKβ expression using siRNA. HBx upregulated cell proliferation and vascular endothelial growth factor (VEGF) production, and these HBx-upregulated phenotypes were abolished by treatment with IKKβ inhibitor Bay 11-7082 or mTOR inhibitor rapamycin. The association of HBx-modulated IKKβ/mTOR/S6K1 signaling with liver tumorigenesis was verified in a HBx transgenic mouse model in which pIKKβ, pS6K1, and VEGF expression was found to be higher in cancerous than non-cancerous liver tissues. Furthermore, we also found that pIKKβ levels were strongly correlated with pTSC1 and pS6K1 levels in HBV-associated hepatoma tissue specimens taken from 95 patients, and that higher pIKKβ, pTSC1, and pS6K1 levels were correlated with a poor prognosis in these patients. Taken together, our findings demonstrate that HBx deregulates TSC1/mTOR signaling through IKKβ, which is crucially linked to HBV-associated HCC development.

Proinflammatory cytokine TNF-α increases the stability of hepatitis B virus X protein through NF-κB signaling

Hepatitis B virus (HBV) X protein (HBx) is a key player in HBV-induced hepatocellular carcinoma (HCC). HBx interacts with several cell signaling molecules, leading to activation of various transcription factors including nuclear factor-kappaB (NF-κB). Activated NF-κB signaling is implicated in many human cancers including HCC. Here, we present evidence that the NF-κB signaling activator, tumor necrosis factor (TNF)-α, induces the accumulation of HBx in cells by increasing protein stability due to reduced proteasomal degradation. The effects of TNF-α on HBx protein stability are mediated via activated NF-κB effector kinases IKKα and IKKβ and p65. The non-IKK-phosphorylable p65-S534A mutant did not induce HBx protein stability; hence, phosphorylation of p65 by IKK is a key step in TNF-α-induced stabilization of HBx. Phospho-p65 showed higher affinity to HBx compared with the non-phosphorylable p65 mutant, suggesting that the interaction of phospho-p65 with HBx might be important for HBx stabilization. We also show that the increased level of HBx in cells cooperates with TNF-α toward activation of NF-κB and expression of NF-κB-regulated genes, indicating a positive feedback loop between HBx and NF-κB signaling. Overall, our study provides evidence for interplay between HBx and NF-κB signaling, which may account for HBV-mediated liver carcinogenesis.

Identification of genes, including the gene encoding p27Kip1, regulated by serine 276 phosphorylation of the p65 subunit of NF-kappaB

Phosphorylation of the p65 subunit of NF-kappaB is required for its transcriptional activity. Recent reports show that phosphorylation of p65 at serine 276 regulates only a subset of genes, such as those encoding IL-6, IL-8, Gro-beta, and ICAM-1. In order to identify additional genes regulated by serine 276 phosphorylation, HepG2 hepatoma cells were infected with adenoviruses encoding either wild-type p65 or the S276A mutant of p65, followed by DNA microarray analysis. The results show that mutation of serine 276 affected the expression of several genes that encode proteins involved in cell cycle regulation, signal transduction, transcription, and metabolism. Notably, expression of S276A increased the mRNA and protein level of p27, a cell cycle inhibitory protein, which led to an increased association of p27 with cdk2, and inhibition of cdk2 activity. Furthermore, while wild-type NF-kappaB is known to increase cell proliferation in a number of different cancer cell lines, our data shows that S276A inhibited cell proliferation. Evidence is mounting that NF-kappaB plays a pivotal role in oncogenesis. Therapeutic agents that regulate the phosphorylation of serine 276 and p27 gene expression, therefore, may be useful as anti-cancer agents in the future.

Progressive changes in hepatoma cells stably transfected with hepatitis B virus X gene

OBJECTIVE

The aim of this study is to investigate the molecular mechanism of hepatocellular carcinoma (HCC) development induced by hepatitis B virus X protein (HBx).

METHODS

We previously established a H7402-X cell line that constitutively expresses HBx protein. In the present study, H7402-X gene expression profiles and proteins were examined using cDNA microarrays and Western blot analysis. Apoptosis was induced by adriamycin in H7402-X cells. The transcriptional activities of NF-kappaB and AP-1 were examined using a luciferase reporter gene.

RESULTS

The DNA expression profiles identified candidate genes showing aberrant expression in cells overexpressing HBx. Western blot analysis showed that cyclin D, cyclin E, survivin, Bcl-2, and PCNA were up-regulated, whereas p27 was down-regulated in H7402-X cells. Treatment with RNAi targeting HBx mRNA led to the down-regulation of these genes. H7402-X cells were resistant to adriamycin-induced apoptosis. Luciferase reporter gene analysis revealed that HBx induces the transcriptional activities of NF-kappaB and AP-1.

CONCLUSION

Our data provide additional insight into cellular targets of HBx, which allows a better understanding of HBx function and the progressive changes during HBx-mediated hepatocarcinogenesis.

NF-kappaB and COX-2 during oral tumorigenesis and in assessment of minimal residual disease in surgical margins

Oral cancer is a major health problem in many parts of the world including India. The molecular mechanisms involved in oral tumorigenesis are not completely understood. Although surgery continues to be the most common treatment modality for this cancer, survival rates of oral cancer patients have still not significantly improved over the last few decades. Classical diagnostic methods are still not sensitive enough in detecting completeness of surgery and assessing minimal residual disease. This study investigated the role of NF-kappaB and COX-2 both in oral cancer progression and assessment of minimal residual disease. Expression of NF-kappaB proteins and its inhibitory protein IkappaB-alpha was evaluated using immunohistochemistry, ELISA and EMSA, while RT-PCR was used to detect COX-2 expression. Cytoplasmic expression as well as nuclear translocation of NF-kappaB proteins increased with histological progression of oral cancer (from normal to leukoplakia to cancer). A similar pattern of expression was observed for COX-2 also. NF-kappaB proteins, both cytoplasmic and nuclear, had a significant negative correlation from tumor to surgical margin to extra margin; COX-2 paralleled the expression of NF-kappaB proteins. Our results thus point to NF-kappaB and COX-2 as participants in oral tumor progression and also to the validation of these two molecular markers in assessing minimal residual disease.

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Identification of the immunogenic domains in HBsAg preS1 region using overlapping preS1 fragment fusion proteins

AIM: The incorporation of hepatitis B virus (HBV) preS1 region into epitope-based vaccines against HBV has been accepted widely, but the incorporate site and size of preS1 sequence is controversial. Therefore our purpose was to further investigate its immunogenic domains for the epitope-based hepatitis B vaccine design.

METHODS: Eight GST fusion proteins containing overlapping preS1 fragments in preS1 (21-119) region were expressed in E.coli. Using these purified fusion proteins, the immunogenic domains in preS1 region were identified in detail in mice and humans by Western blot analysis and ELISA.

RESULTS: The results in mice showed that the immu-nogenic domains mainly existed in preS1 (21-59) and preS1 (95-109). Similarly, these fragments had strong immunogenicity in humans; whereas the other parts except for preS1 (60-70) also had some immunogenicity. More importantly, a major immunogenic domain, preS1 (34-59), which has much stronger immunogenicity, was identified. Additionally, the antibodies against some preS1 fragments, especially preS1 (34-59), were speculated to be virus-neutralizing.

CONCLUSION: Eight GST fusion proteins containing overlapping preS1 fragments were prepared successfully. They were used for the study on the immunogenic dom-ains in preS1 (21-119) region. The preS1 (34-59) fragm-ents were the major immunogenic domains in the preS1 region, and the antibodies against these fragments were speculated to be virus-neutralizing. Therefore, the incorporation of preS1 (34-59) fragments into epitope-based HBV vaccines may be efficient for enhancement of immune response. Additionally, the results also imply that there are more complex immune responses to preS1 region and more abundant immunogenic domains in humans.

Evaluation of nuclear factor-kappaB, urokinase-type plasminogen activator, and HBx and their clinicopathological significance in hepatocellular carcinoma

PURPOSE

Nuclear factor kappaB (NF-kappaB) signaling pathway is an important regulating pathway in human diseases and cancers. One of its downstream target genes is urokinase plasminogen activator (uPA), which is involved in cancer invasion and metastasis. The purpose of this study was to evaluate NF-kappaB activation, uPA up-regulation, and hepatitis B viral X protein (HBx) expression in human hepatocellular carcinoma (HCC) and to assess their clinicopathological significance.

EXPERIMENTAL DESIGN

We evaluated NF-kappaB activation, expression of uPA, and presence of HBx in 32 human HCCs. Their clinicopathological significance was assessed by correlation with the clinicopathological features. Aberrant NF-kappaB signaling pathway and uPA up-regulation mediated by HBx were also analyzed in vitro.

RESULTS

We found that NF-kappaB activation and uPA up-regulation were frequently (56% and 59%, respectively) observed in HCCs, and particularly in HBx-positive HCCs. NF-kappaB activation and uPA overexpression were closely associated with one another (P < 0.0001). Furthermore, both activation of NF-kappaB and up-regulation of uPA were significantly associated with a more aggressive tumor behavior in terms of venous invasion, direct liver invasion, and absence of tumor encapsulation. In vitro, NF-kappaB activation was induced by HBx transfection in HepG2 cells through inhibitor of nuclear factor-kappaB kinase beta (IKKbeta). HBx also up-regulated uPA and enhanced cell invasion synergistically with IKKbeta.

CONCLUSIONS

The data indicate that NF-kappaB dysregulation and uPA overexpression may lead to a more aggressive tumor behavior in HCC. In addition, our data suggest that IKKbeta plays a critical role in the HBx-activated NF-kappaB signaling pathway.

Autonomous activation of hepatitis B virus large surface protein

AIM: To construct the yeast expression vector of hepatitis B virus large surface protein (LHBs), and to study its autonomous activation.

METHODS: The Matchmaker GAL4 two-hybrid technique was used. The LHBs, pre-S1, pre-S2 and SHBs genes were amplified by polymerase chain reaction (PCR) with respective primers. The amplified PCR fragments were then subcloned into the EcoR I/BamH I sites (5'ands) of pGBKT7 vector to obtain the expression vectors including pGBKT7(-)-LHBs, pGBKT7(-)-preS1, pGBKT7(-)-preS2 and pGBKT7(-)-SHBs. This vectors were identifed by PCR and digestion of EcoR I/BamH I. After the constructed vectors were transformed into yeast AH109, the yeast cells were plated on synthetic dropout nutrient medium (SD/-Trp and SD/-Trp-His-Ade) containing x-a-gal for testing their autonomous activation.

RESULTS: The yeast expression vectors were constructed. The yeast cells transformed with pGBKT7-LHB and pGBKT7-preS1 vectors could grow well on both of the media. However, cells transformed with pGBKT7-preS2 and pGBKT7-SHBs vectors could only grow on the SD/-Trp medium.

CONCLUSION: The LHBs functions as a transcriptional transactivator, and serves as the functional GAL4 activation domain (AD) to activate transcription of reporter genes (ADE2, HIS3, MEL1 and LacZ). The autonomous activation of LHBs roots in its pre-S1 domain.

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Screening and identification of genes trans-regulated by HBV pre-S2 protein with cDNA microarray

AIM: To understand the target genes up-regulated or down-regulated by HBV pre-S2 protein, we compared the differentially expressed genes between the hepatoblastoma cell line HepG2 transfected by pcDNA3.1(-) and pcDNA3.1(-)-preS2, respectively with cDNA microarray technique.

METHODS: The HBV pre-S2 coding DNA fragment was amplified with polymerase chain reaction (PCR) technique by using G376-7 plasmid containing the full length of HBV genome as the template. The expressive vector of pcDNA3.1-preS2 was constructed by routine molecular biological methods. The HepG2 cells were transfected by pcDNA3.1(-) and pcDNA3.1(-)-preS2, respectively, using FuGENE6 transfection reagent. The total RNA was isolated and reversely transcribed. The cDNAs were subjected for microarray screening with 1 152 cDNA probes.

RESULTS: The expressive vector was constructed and confirmed by restriction enzyme digestion and DNA sequencing analysis. High quality mRNA and cDNA were prepared and successful microarray screening conducted. From the scanning results, it was found 42 genes were up-regulated and 36 genes down-regulated by pre-S2 protein of HBV.

CONCLUSION: HBV pre-S2 protein is a transactivator. The expression of pre-S2 protein affects the expression spectrum of HBV infected hepatocyte.

Construction of hepatitis B virus X gene expression vector in eucaryotic cells and its transfection in HL-7702 cells

AIM: To establish a human hepatocyte cell line which can express hepatitis B virus (HBV) X gene.

METHODS: HBV X gene was obtained through PCR techn-ology. After A-tailing added, X gene was connected into vector PUCmT. Vector PUCmT-X and PcDNA3 were digested with EcoRI and HindIII. The fragments of X and PcDNA3 were connected to establish reconstituted plasmid PcDNA3-X. Then PcDNA3-X and PcDNA3 were transfected into HL-7702 cells by lipid-mediated transfection. After selected with G418, HL-7702/HBx cells were analysed by the reverse transcription-PCR to confirm the steady expression of X gene in HL-7702.

RESULTS: Reconstituted plasmid PcDNA3-X included the anticipated fragment of HBV X gene was proved by auto-sequencing assay. RT-PCR analysis showed that reconstituted plasmid PcDNA3-X could express the X protein efficiently in HL-7702 cells.

CONCLUSION: Hepatocyte can express HBV X gene, which is an ideal model to study the effect of HBV X gene on the development of hepatitis and hepatocelular carcinoma.

Involvement of NF-kappa B activation in P-glycoprotein expression in vincristine-resistant human gastric cancer cells

AIM: To investigate the effect of vincristine on activation of nuclear factor-kappa B (NF-κB) and expression of p-glycoprotein (P-gp) in vincristine-resistant human gastric cancer SGC7901 cells (SGC7901/VCR) and the parent sensitive clone (SGC7901).

METHODS: NF-κB-DNA binding activity was determined by electrophoretic mobility shift assay (EMSA). Levels of inhibitory B (IB-) and P-gp were measured by cellular-ELISA. And immunocytochemistry was used to detect the translocation of P65.

RESULTS: IN comparison with the parent SGC7901 cells, the basal and vincristine-induced NF-κB-DNA binding activity at various concentrations were all higher in the SGC7901/VCR cells. Concurrent with the NF-κB activation, vincristine-induced IB- degradation and P-gp upregulation were also found to be highly enhanced in the SGC7901/VCR cells than that in the sensitive SGC7901 cells. In the SGC7901/VCR cells, the activation of NF-κB induced by vincristine showed a positive relation with the level of P-gp expression (r = 0.977, P < 0.01). And nuclear translocation of P65 occurred concomitantly with NF-κB activation. Furthermore, the inhibition of NF-κB by MG-132, a proteasome inhibitor, could reduce NF-κB activation, IB- degradation and P-gp upregulation.

CONCLUSION: The enhancement of NF-κB activation correlates with vincristine resistance and NF-κB may play an important role in the regulation of the P-gp expression.

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Overexpression of HBxAg in hepatocellular carcinoma and its relationship with Fas/FasL system

AIM: To study the expression and serum level of HBxAg, Fas and FasL in tissues of HCC patients, and to assess the relationship between HBxAg and Fas/FasL system.

METHODS: Tissues from 50 patients with HCC were tested for the expression of HBxAg, Fas and FasL by S-P immunohistochemistry. Serum levels of sFas/sFasL and HBsAg/HBeAg were measured by ELISA assay. HBV X gene was detected by PCR in serum and confirmed by automatic sequencing. Fifty cases of liver cirrhosis and 30 normal controls were involved in serum analysis.

RESULTS: The expression of HBxAg, Fas and FasL in carcinoma tissues was 96%, 84% and 98%, respectively. Staining of HBxAg, Fas and FasL was observed predominately in cytoplasms, no significant difference was found in intensity between HBxAg, Fas and FasL (P > 0.05). HBxAg, Fas and FasL might express in the same area of carcinoma tissues and this co-expression could be found in most patients with HCC. The mean levels of sFas in serum from HCC, cirrhosis and normal controls were 762.29 ± 391.56 μg·L^-1, 835.36 ± 407.33 μg·L^-1 and 238.27 ± 135.29 μg·L^-1. The mean levels of sFasL in serum from HCC, cirrhosis and normal controls were 156.36 ± 9.61 μg·L^-1, 173.63 ± 18.74 μg·L^-1 and 121.96 ± 7.83 μg·L^-1. Statistical analysis showed that both sFas and sFasL in HCC and cirrhosis patients were significantly higher than those in normal controls (P < 0.01). Serum HBV X gene was found in 32% of HCC patients and 46% of cirrhotic patients. There was no significant relationship between serum level of sFas/sFasL and serum X gene detection (P > 0.05). Eight percent of HCC patients with negative HBsAg and HBeAg in serum might have X gene in serum and HBxAg expression in carcinoma tissues.

CONCLUSION: Our data suggest that HBxAg and Fas/FasL system plays an important role in the development of human HCC. Expression of HBxAg can leads to expression of Fas/ FasL system which and reverse apoptosis of hepatocellular carcinoma induced by FasL.

Interferon alpha inhibits the nuclear factor kappa B activation triggered by X gene product of hepatitis B virus in human hepatoma cells

X gene product of hepatitis B virus (HBV) (HBx) regulates many transcription factors including nuclear factor kappa B (NF-kappaB) and plays a key role in hepatocarcinogenesis. In this study, we demonstrated that the expression of full HBV genome and HBx gene similarly stimulated the transcriptional activity of NF-kappaB in HuH-7 human hepatoma cells, and that interferon (IFN)-alpha as well as dominant negative mutant of IkappaB kinase-alpha effectively inhibited the HBx-mediated NF-kappaB activation, but IFN-gamma did not. These results suggest that IFN-alpha may have a function to block the NF-kappaB activating pathway triggered by HBx in HBV hepatocytes.

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Study on X gene mutation of hepatitis B virus from patients with hepatocellular carcinoma

AIM

To study the association of mutations of hepatitis B virus(HBV) X gene with hepatocellular carcinoma(HCC).

METHODS

The complete X region of HBV from the serum of 5 patients with HCC and 12 patients with chronic hepatitis B (CH) was amplified by PCR and then the purified PCR products were sequenced.

RESULTS

A comparison of 492bp nucleotide sequence of the HBV X gene from 5 HCC patients with that of the several previously reported isolates of different serotype in Genebank showed that the nucleotide homology was 89-96 % and most of the strains were similar to serotype adw. The number of nucleotide changes in the X gene of HBV from HCC group (19.4±12.1) was significantly greater than that from the CH group (4.4±2.4, P =0.00 093).There were 4 models of substitutions in X gene and 6 hot spots found in HCC group and 12 hot spots found in HCC group.

CONCLUSION

The mutations of HBV X gene may be closely associated with the development of HCC.

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Anti-HBV effect of TAT- HBV targeted ribonuclease

AIM: To prepare and purify TAT-HBV targeted ribonuclease fusion protein, evaluate its transduction activity and investigate its effect on HBV replication in 2.2.15 cells.

METHODS: The prokaryotic expression vector pTAT containing TR gene was used in transforming E.coli BL21 (DE3) LysS and TR was expressed with the induction of IPTG. The TAT-TR fusion protein was purified using Ni-NTA-agrose and PD-10 desalting columns, and analyzed by SDS-PAGE. Transduction efficiency of TAT-TR was detected with immunofluorescence assay and the concentration of HBeAg in the supernatant of the 2.2.15 cells was determined via solid-phase radioimmunoassay (spRIA). MTT assay was used to detect the cytotoxicity of TAT-TR.

RESULTS: The SDS-PAGE showed that the TAT-TR fusion protein was purified successfully, and the purity of TAT-TR was 90%. The visualization of TAT-TR by immunofluorescence assay indicated its high efficiency in transducing 2.2.15 cells. RIA result suggests that TAT-TR could inhibit the replication of HBV effectively, it didn’t affect cell growth and had no cytotoxicity.

CONCLUSION: TAT-TR possesses a significant anti-HBV activity and the preparation of TAT-TR fusion protein has laid the foundation for the use of TR in the therapeutic trial of HBV infection.

Identification and characterization of gene 10 transactivated by hepatitis B virus X protein with DNA microarray assay

AIM

To study the target genes transactivated by HBxAg.

METHODS

Specific primers were designed and synthesized according to the HBV DNA sequence of subtype. Polymerase chain reaction (PCR) was conducted to amplify HBxAg coding sequence by using pCP10 plasmid containing 2 copies of head to tail HBV DNA as the template. The expressive vector of pcDNA3-HBxAg was constructed for the transfection of hepatoblastoma cell line HepG2 by Lipofectamine PLUS reagent. Total RNA was prepared from HepG2 and HepG2 cells transfected by pcDNA-HBxAg vector. The RNA was reversely transcribed for further microarray assay.

RESULTS

From the microarray assay, 16 genes were found to be up-regulated, and 58 genes down-regulated. Among them, one gene named XTP10 without known function with 1 206 nt in length, was up-regulated. The encoded protein consisted of 401 amino acid residues (aa).

CONCLUSION

HBxAg is a potential transactivator. DNA microarray is a liable and efficient method for analysis of differentially expressed genes. Molecular biological methods in combination with bioinformatics pave the way for the discovery of new genes transactivated by HBxAg with unknown functions.

Paired mutation in core promoter region of HBV in hepatocellular carcinoma by TDI-FP assay

AIM

To detect the A₁₇₆₂ T and G₁₇₆₄ A paired mutations in the core promoter region of the HBV DNA in the hepatocellular carcinoma, to investigate the relationship between them, and to establish a new method for genotyping of mutation patterns.

METHODS

The target DNA fragment of the HBV core promoter region which contains the paired mutations was amplified by polymerase chain reaction and the FP value of the R110- or TAMRA-labeled ddNTP was detected by TDI-FP assay to determine the nt₁₇₆₂ and nt₁₇₆₄ genotype.

RESULTS

Of 20 cases of hepatocellular carcinoma, 18 (90%) was positive for HBV infection. Through TDI-FP assay, there were 13 /20 for T₁₇₆₂ and A₁₇₆₄ paired mutations, 1/20 heterozygous for T₁₇₆₂-A₁₇₆₄/ A₁₇₆₂-G₁₇₆₄ 4/20 negative for the TDI-FP assay. By sequencing, the positive and heterozygous mutations completely accorded with the TDI-FP assay. In the negative results, 2/4 had 8-nucleotide deletion mutation, thus the mutation detection primer could not complement with the template and gave rise to the "false" negative results. The rate of T₁₇₆₂-A₁₇₆₄ positive mutation rate of HBV DNA in heaptocellular carcinoma was 85%, heterozygous 5%, and wild-type 10%.

CONCLUSION

The HBV infection is very high in the heaptocellular carcinoma. The great frequency of the paired mutations in the core promoter indicates that the paired mutations may be significantly related to the pathogenesis of hepatocellular carcinoma. The established TDI-FP is suitable for high throughput and automated genotyping assays due to its rapid and simple manipulation.

Correlation of splenic ultrasonography, HBV e system and AFP levels in hepatitis B with hepatic fibrosis and carcinogenesis

AIM

To clarify the relationship of splenic ultrasonography in liver fibrosis and carcinogenesis associated with hepatitis B, the spontaneous conversion of HBeAg to Anti-HBe and AFP level.

METHODS

The indexes of spleen ultrasonography of liver fibrosis along with carcinogenensis related with hepatitis B, positive rates of HBeAg or Anti-HBe and AFP levels were compared in different liver fibrosis stages and hepatocellular carcinoma (HCC) related with hepatitis B.

RESULTS

The lengths of spleen (mm) in stages of liver fibrosis S1, S2, S3, S4 and HCC with hepatitis B were 104.6±13.1, 108.7±13.6, 110.5±15.4, 123.0±16.8 and 116.9±28.2, respectively; differences of splenic length between group S4 and groups S1, S2 or S3 were significant statistically (P<0.05). The thicknesses of spleen (mm) in groups S1, S2, S3, S4 and HCC were 35.2±6.3, 37.0±7.7, 37.8±9.6, 43.3±10.8 and 40.811.2, respectively; difference in splenic thickness between group S4 and S1 was significant statistically (P<0.05). The widths of splenic vein (mm) in groups S1, S2, S3, S4 and HCC were 6.0±1.4, 6.5±1.4, 6.8±1.7, 7.8±1.7 and 6.82.6 respectively; there were differences among groups S4 and S1 or S2 (P<0.05) statistically. The positive rates of HBeAg were 92%(23/25), 75.6%(31/41), 68.8%(22/32), 51.9%(14/27) and 13.5%(5/37); and the positive rates of anti-HBe were 4%(1/25), 19.5%(8/41), 25%(8/32), 33.3%(9/27) and 70.3%(26/37) in group S1, S2, S3, S4 and HCC, respectively; difference between each two group among group S1, S2, S3, S4 and HCC was significant(P<0.05). The AFP levels(μg/L) were 11.0±6.7, 49.4±74.5, 112.11±59.0, 179.32±0.8 and 367.46±17.1 in group S1, S2, S3, S4 and HCC, respectively; there were differences among groups HCC and S1 or S2; S4, S3 or S2 and S1 (P<0.05), statistically.

CONCLUSION

The length and thickness of spleen and width of splenic vein were increased as the deterioration of severity of hepatic fibrosis. The length of spleen is more sensitive in indicating the severity of liver fibrosis. Both AFP level and splenic size were elevated as the increase rate of spontaneous conversion from HBeAg to anti-HBe. The risk of hepatocellular carcinoma associated with hepatitis B exists in any stages of liver fibrosis.

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The alteration of PTEN tumor suppressor expression and its association with the histopathological features of human primary hepatocellular carcinoma

PURPOSE

Although deletions or inactivating mutations of the tumor suppressor gene PTEN (phosphatase and tensin homolog deleted on chromosome 10) are involved in the development of a variety of tumors including glioblastoma, melanoma, prostate cancer, breast cancer, endometrial cancers etc., the role of PTEN expression in human primary hepatocellular carcinoma (HCC) has not yet been clarified. The aim of this study is to investigate the involvement of PTEN mRNA and protein expression in HCC.

METHODS

The level of PTEN mRNA expression in HCC specimens was analyzed by Northern blot. PTEN poly-clonal antibody was raised by immunizing New Zealand white rabbit with (His)(6)-tagged PTEN fusion protein and characterized by Western blot. The level of PTEN protein expression was determined by immunohistochemistry. The significance of PTEN in HCC was analyzed by comparing its expression level with the clinicopathological parameters of HCC patients.

RESULTS

Four transcripts of PTEN mRNA at 5.5 kb, 4.4 kb, 2.4 kb, and 1.8 kb were detected in most para-carcinoma liver tissues, and the expression level of PTEN mRNA in carcinoma liver tissues was found to decrease significantly. The poly-clonal antibody raised against histidine-tagged fusion PTEN protein showed specific immuno-reactivity to PTEN protein. Using the specific poly-clonal antibody prepared and characterized by ourselves, we found that PTEN protein was significantly down-regulated in HCC tissues compared with paired para-carcinoma tissues. The protein expression of PTEN is negatively associated with the pathological grading and presence of cancer thrombus of HCC.

CONCLUSIONS

Down-regulation of PTEN expression may play an important role in the development of HCC and the level of PTEN expression may be a potential adjuvant parameter in forecasting the progression and prognosis of HCC patients.

HBV DNA vaccine with adjuvant cytokines induced specific immune responses against HBV infection

AIM: To seek for an effective method to improve the immune responses induced by DNA vaccine expressing HBV surface antigen (pCR3.1-S) in Balb/c mice (H-2^d).

METHODS: The pCR3.1-S plasmid and the eukaryotic expression vectors expressing murine IL-2 (pDOR-IL-2) or IL-12 (pWRG3169) were injected into mice subcutaneously. The immune responses to pCR3.1-S and the adjuvant effect of the cytokines plasmid were studied. Meanwhile the effect of pCR3.1-S on anti-translated subcutaneous tumor of P815 mastocytoma cells stably expressing HBsAg (P815-HBV-S) was also studied. Anti-HBs in serum was detected by enzyme-linked immunoadsordent assay (ELISA) and HBsAg specific cytotoxic T lymphocytes (CTLs) activity was measured by ⁵¹Cr release assay. After three weeks of DNA immunization, the cells of P815-HBV-S were inoculated into mice subcutaneously and the tumor growth was measured every five days. The survival rate and living periods of mice were also calculated.

RESULTS: After 8 wk DNA immunization, the A 450 nm values of sera in mice immunized with pCR3.1, pCR3.1-S and pCR3.1-S codeliveried with IL-2 or IL-12 plasmids were 0.03 ± 0.01, 1.24 ± 0.10, 1.98 ± 0.17 and 1.67 ± 0.12 respectively. Data in mice codeliveried pCR3.1-S with IL-2 or IL-12 plasmids were significantly higher than that of mice injected pCR3.1 or pCR3.1-S only. The HBsAg specific CTL activities in mice coinjected with pCR3.1-S and IL-2 or IL-12 eukaryotic expression vectors were (61.9 ± 7.1)% and (73.3 ± 8.8)%, which were significantly higher than that of mice injected with pCR3.1 (10.1 ± 2.1)% or pCR3.1-S (50.5 ± 6.4)%. The HBsAg specific CTL activities in mice injected with pCR3.1, pCR3.1-S, pCR3.1-S combined with IL-2 or IL-12 eukaryotic expression vectors decreased significantly to (3.2 ± 0.8)%, (10.6 ± 1.4)%, (13.6 ± 1.3)% and (16.9 ± 2.3)% respectively after the spleen cells were treated by anti-CD8⁺ monoclonal antibody, but presented no significant change to anti-CD4⁺ monoclonal antibody or unrelated to monoclonal antibody. The HBV-S DNA vaccine (pCR3.1-S) could evidently inhibit the tumor growth, prolong the survival period of mice and improve the survival rate of mice and these effects could be improved by IL-12 gene codeliveried.

CONCLUSION: HBV DNA vaccine has a strong antigenicity in humoral and cellular immunities, which can be promoted by plasmid expressing IL-2 or IL-12. CD8⁺ cells executed the CTL activities. DNA vaccine may be useful for both prophylaxis and treatment of HBV infection.

Expression of hepatitis B virus X protein in transgenic mice

AIM: To establish a mice model harboring hepatitis B virus x gene (adr subtype) for studying the function of hepatitis B virus X protein, a transactivator of viral and cellular promoter/enhancer elements.

METHODS: Expression vector pcDNA3-HBx, containing CMV promoter and hepatitis B virus x gene open reading fragment, was constructed by recombination DNA technique. Hela cells were cultured in DMEM and transfected with pcDNA3-HBx or control pcDNA3 plasmids using FuGENE6 Transfection Reagent. Expression of pcDNA3-HBx vectors in the transfected Hela cells was confirmed by Western blotting. After restriction endonuclease digestion, the coding elements were microinjected into male pronuclei of mice zygotes. The pups were evaluated by multiplex polymerase chain reaction (PCR) at genomic DNA level. The x gene transgenic mice founders were confirmed at protein level by Western blotting, immunohistochemistry and immunogold transmission electron microscopy.

RESULTS: Expression vector pcDNA3-HBx was constructed by recombination DNA technique and identified right by restriction endonuclease digestion and DNA direct sequencing. With Western blotting, hepatitis X protein was detected in Hela cells transfected with pcDNA3-HBx plasmids, suggesting pcDNA3-HBx plasmids could express in eukaryotic cells. Following microinjection of coding sequence of pcDNA3-HBx, the embryos were transferred to oviducts of psedopregnant females. Four pups were born and survived. Two of them were verified to have the HBx gene integrated in their genomic DNA by multiplex PCR assay, and named C57-TgN (HBx)S MMU1 and C57-TgN (HB x) SMMU3 respectively. They expressed 17KD X protein in liver tissue by Western blotting assay. With the immunohistochemistry, X protein was detected mainly in hepatocytes cytoplasm of transgenic mice, which was furthermore confirmed by immunogold transmission electon microscopy.

CONCLUSION: We have constructed the expression vector pcDNA3-HBx that can be used to study the function of HBx gene in eukaryotic cells in vitro. We also established HBx gene (adr subtype) transgenic mice named C57-TgN (HBx) SMMU harboring HBx gene in their genome and express X protein in hepatocytes, Which might be a valuable animal system for studying the roles of HBx gene in hepatitis B virus life cycle and development of hepatocellular carcinoma in vivo.

Overexpression of p28/gankyrin in human hepatocellular carcinoma and its clinical significance

AIM: To investigate the expression of p28/gankyrin gene and its role in the carcinogenetic process of human hepatocellular carcinoma (HCC).

METHODS: 64 specimens of HCC and para-carcinoma tissues, 22 specimens of non-tumor liver tissues (7 normal, 15 cirrhosis), 10 specimens of normal human tissues and 5 hepatoma cell lines were studied for the expression of p28/gankyrin by Northern blot. The expression of p28/gankyrin protein was detected immunohistochemically by using the specific polyclonal antibody.

RESULTS: Northern blot analysis indicated that the expression of p28/gankyrin mRNA was intensively distributed in brain and heart, weakly in lung, spleen and muscle, undetectable in digestive system including liver, pancreas, stomach, small and large intestines. p28/gankyrin mRNA was absent in normal liver, weakly detected in liver cirrhosis and in 18 of 64 para-carcinoma liver tissues. In contrast, the expression of p28/gankyrin mRNA was intensively detected in all 5 hepatoma cell lines tested, markedly increased in 57 of 64 and moderately increased in 5 of 64 HCC samples. In comparison with liver cirrhosis and para-carcinoma liver tissues, the average expression of p28/gankyrin mRNA in HCC was increased 3.6- (2.901 ± 0.507 vs 0.805 ± 0.252, P < 0.05) and 5.2-fold (2.901 ± 0.507 vs 0.557 ± 0.203, P < 0.01), respectively. In addition, p28/gankyrin mRNA expression level was higher in HCC with portal vein tumor thrombus and microscopic hepatic vein involvement (P = 0.021 and P = 0.047, respectively). The overexpression of p28/gankyrin protein in HCC was targeted in hepatic tumor cells, not in bile duct cells and other interstitial cells.

CONCLUSION: Overexpression of p28/gankyrin in HCC plays an important role and contributes to the metastasis potential in the process of carcinogenesis. p28/gankyrin may become a specific biological tissue marker for the pathological diagnosis of HCC.

Anti-inflammatory effect of cholecystokinin and its signal transduction mechanism in endotoxic shock rat

AIM: To study the anti-inflammatory effects of cholecystokinin-octapeptide (CCK-8) on lipopolysaccharide (LPS)-induced endotoxic shock (ES) and further investigate its signal transduction pathways involving p38 mitogen-activated protein kinase (MAPK) and IκB-α.

METHODS: Eighty-four rats were divided randomly into four groups: LPS (8 mg·kg^-1, iv) induced ES; CCK-8 (40 μg·kg^-1, iv) pretreatment 10 min before LPS (8 mg·kg^-1); CCK-8 (40 μg·kg^-1, iv) or normal saline (control) groups. The inflammatory changes of lung and spleen, phagocytic function of alveolar macrophage, quantification of inflammatory cells in bronchoalveolar lavage (BAL) were investigated in rats by using hematoxylin and eosin (HE) staining, phagocytosis of Candida albicans and differential cell counting. Nitric oxide (NO) production in serum, lung and spleen was measured with the Griess reaction. The mechanism involving p38 MAPK and IκB-α signal pathways was investigated by Western blot.

RESULTS: Inflammatory changes of lung and spleen induced by LPS were alleviated by CCK-8, the increase of NO induced by LPS in serum, lung and spleen was significantly inhibited and the neutrophil infiltration in BAL was significantly reduced by CCK-8. The number of neutrophils was (52 ± 10) × 10⁶ cells•L^-1 in LPS group, while it decreased to (18 ± 4) × 10⁶ cells•L^-1 in CCK-8+LPS (P < 0.01). The phagocytic rate of CCK-8 group increased to (62.49 ± 9.49)%, compared with control group (48.16 ± 14.20)%, P < 0.05. The phagocytosis rate was (85.14 ± 4.64)% in LPS group, which reduced to (59.33 ± 3.14)% in CCK-8+LPS group (P < 0.01). The results of phagocytosis indexes showed similar changes. CCK-8 may play an important role in increasing the expression of p38 MAPK and decreasing the degradation of IκB-α in lung and spleen of ES rats.

CONCLUSION: CCK-8 can result in anti-inflammatory effects, which may be related to activation of p38 MAPK and inhibition on the degradation of IκB-α.

Hepatoprotective role of ganoderma lucidum polysaccharide against BCG-induced immune liver injury in mice

AIM: To examine the effect of ganoderma lucidum polysaccharide (GLP) on the immune liver injury induced by BCG infection, and investigate the relationship between degrees of hepatic damage and NO production in mice.

METHODS: Immune hepatic injury was markedly induced by BCG-pretreatment (125 mg·kg^-1, 2-week, iv) or by BCG-pretreatment plus lipopolysaccharide (LPS, 125 μg·kg^-1, 12-hour, iv) in mice in vivo. Hepatocellular damage induced by BCG-pretreated plus inflammatory cytokines mixture (CM), which was included TNF-α, IL-1β, IFN-γ and LPS in culture medium in vitro. Administration of GLP was performed by oral or incubating with culture medium at immune stimuli simultaneity. Liver damage was determined by activity of alanine aminotransferase (ALT) in serum and in hepatocytes cultured supernatant, by liver weight changes and histopathological examination. NO production in the cultured supernatant was determined by the Griess reaction. Moreover, inducible nitric oxide synthase (iNOS) protein expression was also examinated by immunohistochemical method.

RESULTS: Immune hepatic injury was markedly induced by BCG or BCG plus inflammatory cytokines in BALB/c mice in vivo and in vitro. Under BCG-stimulated condition, augment of the liver weight and increase of the serum/supernatant ALT level were observed, as well as granuloma forming and inflammatory cells soakage were observed by microscopic analysis within liver tissues. Moreover, NO production was also increased by BCG or/and CM stimuli in the culture supernatant, and a lot of iNOS positive staining was observed in BCG-prestimulated hepatic sections. Application of GLP significantly mitigated hepatic tumefaction, decreased ALT enzyme release and NO production in serum/supernatant, improved the pathological changes of chronic and acute inflammation induced by BCG-stimuli in mice. Moreover, the immunohistochemical result showed that GLP inhibited iNOS protein expression in BCG-immune hepatic damage model.

CONCLUSION: The present study indicates that NO participates in immune liver injury induced by Mycobacterium bovis BCG infection. The mechanisms of protective roles by GLP for BCG-induced immune liver injury may be due to influence NO production in mice.

Applying a highly specific and reproducible cDNA RDA method to clone garlic up-regulated genes in human gastric cancer cells

AIM: To develop and optimize cDNA representational difference analysis (cDNA RDA) method and to identify and clone garlic up-regulated genes in human gastric cancer (HGC) cells.

METHODS: We performed cDNA RDA method by using abundant double-stranded cDNA messages provided by two self-constructed cDNA libraries (Allitridi-treated and paternal HGC cell line BGC823 cells cDNA libraries respectively). BamH I and Xho I restriction sites harbored in the library vector were used to select representations. Northern and Slot blots analyses were employed to identify the obtained difference products.

RESULTS: Fragments released from the cDNA library vector after restriction endonuclease digestion acted as good marker indicating the appropriate digestion degree for library DNA. Two novel expressed sequence tags (ESTs) and a recombinant gene were obtained. Slot blots result showed a 8-fold increase of glia-derived nexin/protease nexin 1 (GDN/PN1) gene expression level and 4-fold increase of hepatitis B virus x-interacting protein (XIP) mRNA level in BGC823 cells after Allitridi treatment for 72 h.

CONCLUSION: Elevated levels of GDN/PN1 and XIP mRNAs induced by Allitridi provide valuable molecular evidence for elucidating the garlic's efficacies against neurodegenerative and inflammatory diseases. Isolation of a recombinant gene and two novel ESTs further show cDNA RDA based on cDNA libraries to be a powerful method with high specificity and reproducibility in cloning differentially expressed genes.

Construction and characterization of an experimental ISCOMS-based hepatitis B polypeptide vaccine

AIM: To characterize the biochemical and immunological properties of an experimental ISCOMS vaccine prepared from a novel therapeutic polypeptide based on T cell epitopes of HBsAg, and a heptatis B-ISCOMS was prepared and investigated.

METHODS: An immunostimulating complexes (ISCOMS)-based vaccine containing a novel therapeutic hepatits B polypeptide was prepared by dialysis method, and its formation was visualized by electron microscopy and biochemically verified by SDS-polyacrylamide gel electrophoresis. Amount of the peptide within ISCOMS was determined by Bradford assay, and specific CTL response was detected by ELISPOT assay.

RESULTS: Typical cage-like structures of submicroparticle with a diameter of about 40 nm were observed by electron microscopy. Results from Bradford assay showed that the level of peptide incorporation was about 0.33 g•L⁻¹. At the paralleled position close to the sixth band of the molecular weight marker (3480 kDa) a clear band was shown in SDS-PAGE analysis, indicating successful incorporation of polypeptide into ISCOMS. It is suggested that ISCOMS delivery system could efficiently improve the immunogenicity of polypeptide and elicit specific immune responses in vivo by the results of ELISPOT assay, which showed that IFN-γ producing cells (specific CTL responses) were increased (spots of ISCOMS-treated group: 47 ± 5, n = 3; control group: 5 ± 2, n = 3).

CONCLUSION: ISCOMS-based hepatitis B polypeptide vaccine is successfully constructed and it induces a higher CTL response compared with short polypeptides vaccine in vivo.

Anti-HBV hairpin ribozyme-mediated cleavage of target RNA in vitro

AIM: To study the preparation and cleavage activity of HpRz directed against the transcript of HBV core gene in vitro.

METHODS: HpRz gene designed by computer targeting the transcript of HBV core gene was cloned into the vector p1.5 between 5’-cis-Rz and 3’-cis-Rz. ³²p-labeled HpRz transcript proved whether the vector fit for the preparation of hairpin ribozyme in vitro. ³²p-labeled pKC transcript containing HBV core region as target-RNA was transcribed using T₇ RNA polymerase and purified by denaturing PAGE. Cold HpRz transcript was incubated with ³²p-labeled target-RNAs under different conditions and radio autographed after denaturing polyacrylamide gel electrophoresis.

RESULTS: HpRz has the specific ability of cleavage of target RNA at 37 °C and 12 mM MgCl₂. K_m = 26.31 nmol/L, K_cat = 0.18/min. These results revealed that the design of HpRz was correct.

CONCLUSION: HpRz prepared in this study possesses specific catalytic activity from the identification of cleavage activity. These results indicate that hairpin ribozyme may intracellularly inhibit the replication of HBV, therefore it may become a novel potent weapon for the treatment of hepatitis B.

Clinical application of serial operations with preserving spleen

AIM: To evaluate the clinical application of serial operations with preservation of spleen.

METHODS: Serial operations with preserving spleen were performed on 211 cases in our hospital from 1980 to 2000. The patient’s age ranged from 13 to 56 years, averaging 38 years. Diseases included splenic injury in 171 cases, portal hypertension in 9 cases, splenic cyst in 10 cases, and the lesion of pancreatic body and tail in 21 cases.

RESULTS: All the cases were cured, and 129 patients were followe dup from 3 mo to 3 years with the leukocyte phagocytosis test, detection of immunoglubin, CT, ^99mTc scanning and ultrasonography. The results were satisfactory.

CONCLUSION: The operations with preserving spleen were safe, feasible, and worth of clinical application.