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Feitelson MA, Larkin JD, Schinazi RF. Hepatitis B virus transgenic severe combined immunodeficient mouse model of acute and chronic liver disease. METHODS IN MOLECULAR MEDICINE 2004; 96:269-87. [PMID: 14762277 DOI: 10.1385/1-59259-670-3:269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
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52
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Lian Z, Liu J, Li L, Li X, Tufan NLS, Wu MC, Wang HY, Arbuthnot P, Kew M, Feitelson MA. Human S15a expression is upregulated by hepatitis B virus X protein. Mol Carcinog 2004; 40:34-46. [PMID: 15108328 DOI: 10.1002/mc.20012] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The hepatitis B virus (HBV)-encoded X antigen (HBxAg) may contribute to the development of hepatocellular carcinoma (HCC) through the upregulated expression of selected cellular genes. To identify these genes, RNAs isolated from HBxAg-positive and -negative HepG2 cells were compared by PCR select cDNA subtraction. One gene overexpressed in HBxAg-positive cells by Northern and Western blotting is the ribosomal protein S15a. The S15a mRNA is 535 base pairs, encoding a protein 130 amino acids long with a molecular weight of 14.3 kDa. S15a expression was upregulated in HBV-infected livers, where it costained with HBxAg. Overexpression of S15a stimulated cell growth, colony formation in soft agar, and tumor formation in SCID mice. Hence, HBxAg upregulated the expression of S15a, the latter of which participates in the development of HCC, perhaps by altering the integrity of translation.
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Pan J, Clayton M, Feitelson MA. Hepatitis B virus X antigen promotes transforming growth factor-beta1 (TGF-beta1) activity by up-regulation of TGF-beta1 and down-regulation of alpha2-macroglobulin. J Gen Virol 2004; 85:275-282. [PMID: 14769885 DOI: 10.1099/vir.0.19650-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Hepatitis B virus (HBV) X antigen (HBxAg) may contribute to the development of hepatocellular carcinoma (HCC) by activation of signalling pathways such as NF-kappaB. To identify NF-kappaB target genes differentially expressed in HBxAg-positive compared to -negative cells, HepG2 cells consistently expressing HBxAg (HepG2X cells) were stably transfected with pZeoSV2 or pZeoSV2-IkappaBalpha. mRNA from each culture was isolated and compared by PCR select cDNA subtraction. The results showed lower levels of alpha(2)-macroglobulin (alpha(2)-M) in HepG2X-pZeoSV2 compared to HepG2X-pZeoSV2-IkappaBalpha cells. This was confirmed by Northern and Western blotting, and by measurement of extracellular alpha(2)-M levels. Elevated transforming growth factor-beta1 (TGF-beta1) levels were also seen in HepG2X compared to control cells. Serum-free conditioned medium (SFCM) from HepG2X cells suppressed DNA synthesis in a TGF-beta-sensitive cell line, Mv1Lu. The latter was reversed when the SFCM was pretreated with exogenous, activated alpha(2)-M or with anti-TGF-beta. Since elevated TGF-beta1 promotes the development of many tumour types, these observations suggest that the HBxAg-mediated alteration in TGF-beta1 and alpha(2)-M production may contribute importantly to the pathogenesis of HCC.
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Liu J, Feitelson MA. Detection of hepatitis B virus X antigen by immunohistochemistry and Western blotting. METHODS IN MOLECULAR MEDICINE 2004; 95:71-84. [PMID: 14762297 DOI: 10.1385/1-59259-669-x:71] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
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55
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Lian Z, Liu J, Li L, Li X, Tufan NLS, Clayton M, Wu MC, Wang HY, Arbuthnot P, Kew M, Feitelson MA. Upregulated expression of a unique gene by hepatitis B x antigen promotes hepatocellular growth and tumorigenesis. Neoplasia 2003; 5:229-44. [PMID: 12869306 PMCID: PMC1502406 DOI: 10.1016/s1476-5586(03)80055-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Hepatitis B x antigen (HB x Ag) is a trans-activating protein that may be involved in hepatocarcinogenesis, although few natural effectors of HB x Ag that participate in this process have been identified. To identify additional effectors, whole cell RNA isolated from HB x Ag-positive and HB x Ag-negative HepG2 cells were compared by polymerase chain reaction select cDNA subtraction, and one clone, upregulated gene, clone 11 (URG11), was chosen for further characterization. Elevated levels of URG11 mRNA and protein were observed in HB x Ag-positive compared to HB x Ag-negative HepG2 cells. Costaining was observed in infected liver (P < 0.01). URG11 stimulated cell growth in culture (P < 0.01), anchorage-independent growth in soft agar (P < 0.001), and accelerated tumor formation (P < 0.01), and yielded larger tumors (P < 0.02) in SCID mice injected subcutaneously with HepG2 cells. These data suggest that URG11 is a natural effector of HB x Ag that may promote the development of hepatocellular carcinoma.
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Tufan NLS, Lian Z, Liu J, Pan J, Arbuthnot P, Kew M, Clayton MM, Zhu M, Feitelson MA. Hepatitis Bx antigen stimulates expression of a novel cellular gene, URG4, that promotes hepatocellular growth and survival. Neoplasia 2002; 4:355-68. [PMID: 12082552 PMCID: PMC1531705 DOI: 10.1038/sj.neo.7900241] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2001] [Accepted: 01/24/2002] [Indexed: 12/16/2022]
Abstract
Hepatitis B virus encoded X antigen (HBxAg) may contribute to the development of hepatocellular carcinoma (HCC) by up- or downregulating the expression of cellular genes that promote cell growth and survival. To test this hypothesis, HBxAg-positive and -negative HepG2 cells were constructed, and the patterns of cellular gene expression compared by polymerase chain reaction select cDNA subtraction. The full-length clone of one of these upregulated genes (URG), URG4, encoded a protein of about 104 kDa. URG4 was strongly expressed in hepatitis B-infected liver and in HCC cells, where it costained with HBxAg, and was weakly expressed in uninfected liver, suggesting URG4 was an effector of HBxAg in vivo. Overexpression of URG4 in HepG2 cells promoted hepatocellular growth and survival in tissue culture and in soft agar, and accelerated tumor development in nude mice. Hence, URG4 may be a natural effector of HBxAg that contributes importantly to multistep hepatocarcinogenesis.
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Feitelson MA, Sun B, Satiroglu Tufan NL, Liu J, Pan J, Lian Z. Genetic mechanisms of hepatocarcinogenesis. Oncogene 2002. [PMID: 11971194 DOI: 10.1038/sj/onc/1205434] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The development of hepatocellular carcinoma (HCC) is a multistep process associated with changes in host gene expression, some of which correlate with the appearance and progression of tumor. Preneoplastic changes in gene expression result from altered DNA methylation, the actions of hepatitis B and C viruses, and point mutations or loss of heterozygosity (LOH) in selected cellular genes. Tumor progression is characterized by LOH involving tumor suppressor genes on many chromosomes and by gene amplification of selected oncogenes. The changes observed in different HCC nodules are often distinct, suggesting heterogeneity on the molecular level. These observations suggest that there are multiple, perhaps redundant negative growth regulatory pathways that protect cells against transformation. An understanding of the molecular pathogenesis of HCC may provide new markers for tumor staging, for assessment of the relative risk of tumor formation, and open new opportunities for therapeutic intervention.
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Feitelson MA, Sun B, Satiroglu Tufan NL, Liu J, Pan J, Lian Z. Genetic mechanisms of hepatocarcinogenesis. Oncogene 2002; 21:2593-604. [PMID: 11971194 DOI: 10.1038/sj.onc.1205434] [Citation(s) in RCA: 234] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2001] [Revised: 02/15/2002] [Accepted: 02/21/2002] [Indexed: 01/06/2023]
Abstract
The development of hepatocellular carcinoma (HCC) is a multistep process associated with changes in host gene expression, some of which correlate with the appearance and progression of tumor. Preneoplastic changes in gene expression result from altered DNA methylation, the actions of hepatitis B and C viruses, and point mutations or loss of heterozygosity (LOH) in selected cellular genes. Tumor progression is characterized by LOH involving tumor suppressor genes on many chromosomes and by gene amplification of selected oncogenes. The changes observed in different HCC nodules are often distinct, suggesting heterogeneity on the molecular level. These observations suggest that there are multiple, perhaps redundant negative growth regulatory pathways that protect cells against transformation. An understanding of the molecular pathogenesis of HCC may provide new markers for tumor staging, for assessment of the relative risk of tumor formation, and open new opportunities for therapeutic intervention.
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Larkin J, Clayton MM, Liu J, Feitelson MA. Chronic ethanol consumption stimulates hepatitis B virus gene expression and replication in transgenic mice. Hepatology 2001; 34:792-7. [PMID: 11584377 DOI: 10.1053/jhep.2001.27565] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Epidemiologic observations show a higher frequency of hepatitis B virus (HBV) serologic markers in chronic alcoholics compared with the general population. This may be the result of an increased susceptibility of alcoholics to infection and/or to an ethanol-mediated stimulation of HBV gene expression and replication. To test the latter hypothesis, HBV transgenic SCID mice, which support consistent levels of virus replication, were fed with a standard Lieber-DiCarli or isocaloric diet for 5 weeks. In ethanol-fed mice, the levels of hepatitis B surface antigen (HBsAg) and viral DNA in serum increased by up to 7-fold compared with mice fed the control diet. Ethanol-treated mice also had elevated HBV-RNA levels, and increased expression of surface, core, and X antigens in the liver, especially in the pericentral regions. None of these changes were observed in transgenic mice fed isocaloric diets. Thus, chronic alcohol consumption alters the patterns of HBV gene expression and replication in the serum and liver of HBV transgenic SCID mice, and may provide a partial explanation for the increased frequency of HBV markers among alcoholics.
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Abstract
The narrow host range of infection and lack of suitable tissue culture systems for the propagation of hepatitis B and C viruses are limitations that have prevented a more thorough understanding of persistent infection and the pathogenesis of chronic liver disease. With hepatitis B virus (HBV), this lack of knowledge has been partially overcome by the discovery and characterization of HBV-like viruses in wild animals. With hepatitis C virus (HCV), related flaviviruses have been used as surrogate systems for such studies. Other laboratories have developed transgenic mice that express virus gene products and/or support virus replication. Some HBV transgenic mouse models develop fulminant hepatitis, acute hepatitis, or chronic liver disease after adoptive transfer, and others spontaneously develop hepatocellular carcinoma (HCC), as in human infections. Among HCV transgenic mice, most develop no disease, but acute hepatitis has been observed in one model, and HCC in another. Although mice are not susceptible to HBV and HCV, their ability to replicate these viruses and to develop liver diseases characteristic of human infections provides new opportunities to study pathogenesis and develop novel therapeutics.
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Lian Z, Liu J, Pan J, Satiroglu Tufan NL, Zhu M, Arbuthnot P, Kew M, Clayton MM, Feitelson MA. A cellular gene up-regulated by hepatitis B virus-encoded X antigen promotes hepatocellular growth and survival. Hepatology 2001; 34:146-57. [PMID: 11431746 DOI: 10.1053/jhep.2001.25545] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Polymerase chain reaction (PCR) select complementary DNA (cDNA) subtraction of hepatitis B x antigen (HBxAg)-positive compared with -negative HepG2 cells resulted in the up-regulated expression of a cellular gene that encodes a transcript of 745 bases and a polypeptide 99 amino acids long. GenBank analysis revealed extensive homology with the amino terminal domain of cellular multidrug resistant proteins (MRP), although overexpression of this gene did not confer an MRP phenotype. In situ hybridization and immunostaining showed colocalized expression with HBxAg in the liver of hepatitis B carriers. Overexpression of this protein stimulated the growth of HepG2 cells in serum-free medium, and partially protected cells from anti-Fas-mediated killing, but did not promote growth in soft agar or tumor formation in nude mice. Introduction of the dominant negative inhibitor of nuclear factor kappaB (IkappaBalpha) into HBxAg-positive HepG2 cells decreased the levels of messenger RNA (mRNA) and protein, suggesting that its up-regulation is nuclear factor kappaB (NF-kappaB) dependent. Hence, HBxAg activation of NF-kappaB may result in the up-regulation of a cellular protein that promotes growth factor-independent survival and protects against Fas-mediated killing. This factor may contribute to the persistence of infected hepatocytes during chronic infection, which is important for the later development of hepatocellular carcinoma (HCC).
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MESH Headings
- ATP-Binding Cassette Transporters
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Blotting, Western
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/pathology
- Carcinoma, Hepatocellular/virology
- Cell Division
- Cell Survival
- Cloning, Molecular
- DNA, Complementary/chemistry
- Drug Resistance, Multiple/genetics
- Gene Expression
- Gene Expression Regulation
- Humans
- In Situ Hybridization
- Liver Neoplasms/genetics
- Liver Neoplasms/pathology
- Liver Neoplasms/virology
- Mice
- Mice, Nude
- Molecular Sequence Data
- Multidrug Resistance-Associated Proteins
- NF-kappa B/pharmacology
- Polymerase Chain Reaction
- Proteins/chemistry
- Proteins/genetics
- RNA, Messenger/analysis
- Sequence Homology
- Trans-Activators/chemistry
- Trans-Activators/genetics
- Trans-Activators/physiology
- Transfection
- Tumor Cells, Cultured
- Viral Regulatory and Accessory Proteins
- fas Receptor/immunology
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Pan J, Duan LX, Sun BS, Feitelson MA. Hepatitis B virus X protein protects against anti-Fas-mediated apoptosis in human liver cells by inducing NF-kappa B. J Gen Virol 2001; 82:171-182. [PMID: 11125170 DOI: 10.1099/0022-1317-82-1-171] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The hepatitis B virus-encoded X antigen (HBxAg) may contribute to the development of liver cancer, in part, by stimulating the growth and survival of infected cells in the face of ongoing immune responses. Given that the Fas ligand/receptor system contributes to the pathogenesis of chronic hepatitis B, experiments were designed to test the hypothesis that HBxAg mediates resistance of liver cells to anti-Fas killing. Accordingly, when HBxAg was introduced into HepG2 cells, it rendered these cells partially resistant to killing by anti-Fas. In HepG2 cells replicating virus, protection against anti-Fas killing was also observed, but to a lesser extent. Survival correlated with the activation of nuclear factor kappa B (NF-kappa B) by HBxAg. Sensitivity to anti-Fas was observed in control cells, and was re-established in HepG2X cells stably transfected with the dominant negative inhibitor of NF-kappa B, I kappa B alpha. HBxAg activation of NF-kappa B was also associated with decreased levels of endogenous I kappa B alpha mRNA. Hence, HBxAg stimulation of NF-kappa B promotes the survival of liver cells against Fas killing. This may contribute to the persistence of infected hepatocytes during chronic infection.
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Abstract
Hepatitis B virus (HBV) is an important etiologic agent of chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). Although the mechanism whereby HBV causes HCC is not fully understood, it is likely that there are many relevant molecular pathways that contribute to the development of HBV-associated HCC. This review provides an overview of some of these proposed pathways and their relative importance. It also raises questions on basic and translational research that will signficantly contribute to the better understanding of underlying mechanisms, prevention, and treatment of this tumor type.
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Abstract
Hepatitis B virus (HBV) is an important etiologic agent of chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). Although the mechanism whereby HBV causes HCC is not fully understood, it is likely that there are many relevant molecular pathways that contribute to the development of HBV-associated HCC. This review provides an overview of some of these proposed pathways and their relative importance. It also raises questions on basic and translational research that will signficantly contribute to the better understanding of underlying mechanisms, prevention, and treatment of this tumor type.
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Larkin J, Clayton M, Sun B, Perchonock CE, Morgan JL, Siracusa LD, Michaels FH, Feitelson MA. Hepatitis B virus transgenic mouse model of chronic liver disease. Nat Med 1999; 5:907-12. [PMID: 10426314 DOI: 10.1038/11347] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
A model for hepatitis B virus-associated chronic liver disease has been made using cloned hepatitis B virus DNA as a transgene in a severe combined immunodeficient host. These mice consistently support virus gene expression and replication. After adoptive transfer of unprimed, syngeneic splenocytes, these mice cleared virus from liver and serum, and developed chronic liver disease. This model will permit identification of the host and virus contributions to chronic liver disease in the absence of tolerance.
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MESH Headings
- Adoptive Transfer
- Alanine Transaminase/blood
- Animals
- DNA, Viral/blood
- Disease Models, Animal
- Female
- Fluorescent Antibody Technique, Indirect
- Hepatitis B virus/genetics
- Hepatitis B virus/isolation & purification
- Hepatitis B, Chronic/blood
- Hepatitis B, Chronic/genetics
- Hepatitis B, Chronic/pathology
- Hepatitis B, Chronic/virology
- Liver/pathology
- Liver/virology
- Male
- Mice
- Mice, Inbred C3H
- Mice, SCID
- Mice, Transgenic
- Spleen/cytology
- Transgenes/genetics
- Virus Replication/genetics
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Lian Z, Pan J, Liu J, Zhang S, Zhu M, Arbuthnot P, Kew M, Feitelson MA. The translation initiation factor, hu-Sui1 may be a target of hepatitis B X antigen in hepatocarcinogenesis. Oncogene 1999; 18:1677-87. [PMID: 10208429 DOI: 10.1038/sj.onc.1202470] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The role of hepatitis B virus X antigen in the development of hepatocellular carcinoma was explored by stably transfecting HepG2 cells with an X antigen expression vector, and identifying the differences in gene expression that distinguish X positive from X negative cells by subtractive PCR. One differentially expressed gene, the human homolog of sui1 (hu-sui1), encodes a translation initiation factor whose expression was suppressed by X antigen in HepG2 cells. Hu-Sui1 was also expressed in nontumor liver but not in tumor cells from patients with hepatocellular carcinoma. Introduction of hu-sui1 into HepG2 cells inhibited cell growth in culture, in soft agar, and partially inhibited tumor formation in nude mice. Hence, the suppression of hu-sui1 by X antigen may result in the abrogation of negative growth regulation and contribute to the development of hepatocellular carcinoma.
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67
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Feitelson MA. Hepatitis B x antigen and p53 in the development of hepatocellular carcinoma. JOURNAL OF HEPATO-BILIARY-PANCREATIC SURGERY 1999; 5:367-74. [PMID: 9931385 DOI: 10.1007/s005340050060] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Hepatitis B virus (HBV) is one of the major etiological agents responsible for the appearance of chronic liver diseases, including hepatocellular carcinoma (HCC). There is increasing evidence that the HBV excoded x antigen (HBxAg) is involved in one or more steps that contribute to multistep hepatocarcinogenesis. Recent work has now defined one of these steps as the physical binding and functional inactivation of the tumor suppressor protein, p53, by HBxAg. The centrality of p53 to genomic stability, cell cycle arrest, induction of apoptosis, and in senescence related pathways, suggests that its disruption by HBxAg will result in genomic instability, loss of cell cycle control, a lower apoptotic rate, and an extension in the life span of HBV-infected cells. It is proposed that HBxAg/p53 complex formation represents one of several steps whereby HBV contributes to the development of HCC.
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Kondo R, Feitelson MA, Strayer DS. Use of SV40 to immunize against hepatitis B surface antigen: implications for the use of SV40 for gene transduction and its use as an immunizing agent. Gene Ther 1998; 5:575-82. [PMID: 9797861 DOI: 10.1038/sj.gt.3300623] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have described a novel gene transfer system, in which replication-incompetent, T antigen-deleted simian virus-40 (SV40) is used as the transduction vehicle. We report here successful immunization using such an SV40-derived viral vector. Hepatitis B surface antigen (HBsAg) cDNA was cloned downstream of two tandem SV40 early promoters to yield a T antigen-deficient SV40 derivative, SV(HBS). Cultured TC7 cells were exposed to SV(HBS), and expression of HBsAg was detected 24 h later by Northern blot and RT-PCR analysis. Immunochemistry and Western blot analysis were also performed 24 h after infection to detect expression of HBsAg. Once it was ascertained that we could express HBsAg in this way, we used SV(HBS) to elicit anti-HBs. SV(HBS) was injected intraperitoneally or subcutaneously into mice every 4 weeks. These mice were bled every 2 weeks and their sera assayed for antibody activity against HBsAg and SV40. Production of anti-HBs was measured by ELISA and confirmed by Western blot analysis, both of which demonstrated significant levels of anti-HBs after the second injection. We also tested production of anti-SV40 antibodies by the ability of sera to neutralize SV(HBS) infectivity. We found no evidence of neutralization of SV(HBS) infectivity even after eight inoculations. Thus, replication-incompetent SV40 is itself not a strong antigen. Our data suggest that SV40-based transduction systems may be a useful vehicle for immunization and for other gene transfer applications when a need for multiple inoculations is anticipated.
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69
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Wang LY, Chen CJ, Zhang YJ, Tsai WY, Lee PH, Feitelson MA, Lee CS, Santella RM. 4-Aminobiphenyl DNA damage in liver tissue of hepatocellular carcinoma patients and controls. Am J Epidemiol 1998; 147:315-23. [PMID: 9482507 DOI: 10.1093/oxfordjournals.aje.a009452] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Epidemiologic studies have suggested that cigarette smoking is a risk factor for the development of hepatocellular carcinoma (HCC). To further investigate this relation, the authors measured levels of 4-aminobiphenyl-DNA adducts by an immunoperoxidase method in surgical liver tissues obtained between 1984 and 1995 from 105 Taiwanese patients with histologically confirmed HCC and 37 Taiwanese patients with metastatic liver tumors or intrahepatic stones. Information on clinicopathologic characteristics, cigarette smoking, and alcohol drinking was abstracted from hospital charts. Mean relative staining intensity for 4-aminobiphenyl-DNA was slightly higher in tumor tissues than in nontumor tissues obtained from HCC patients. Both mean intensities were significantly higher than the mean intensity of control tissues taken from non-HCC patients. However, no difference in mean relative staining intensity was found between smokers and nonsmokers in tissues obtained from non-HCC patients, or in tumor or nontumor tissues taken from HCC cases. After stratification of the relative staining intensities of 4-aminobiphenyl-DNA adduct levels into tertiles according to the total numbers of control tissues analyzed, there was a monotonically increasing risk of HCC. Odds ratios were 4.14 (95% confidence interval (CI) 1.15-15.50) and 9.71 (95% CI 2.82-34.86) for medium and high adduct levels compared with low adduct levels, respectively. The linear relation between adduct levels in liver tissue and HCC risk was also significant after adjustment for covariates, including hepatitis B surface antigen (HBsAg) status. The multivariate adjusted odds ratios were 3.41 (95% CI 0.82-14.25) and 6.48 (95% CI 1.59-26.50) for medium and high adduct levels, respectively. Moreover, there were monotonically increasing HCC risks for higher adduct levels in both HBsAg carriers and noncarriers. The increased risk ratios were more pronounced in noncarriers than in carriers. However, because of the small numbers of subjects, especially controls positive for HBsAg, the interaction between HBsAg status and 4-aminobiphenyl-DNA adduct level was not significant. Among HCC cases, none of the clinicopathologic characteristics were associated with relative staining intensity. These results indicate that 4-aminobiphenyl exposure, which is primarily a result of cigarette smoking, plays a role in the development of HCC in humans.
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70
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Sun BS, Zhu X, Clayton MM, Pan J, Feitelson MA. Identification of a protein isolated from senescent human cells that binds to hepatitis B virus X antigen. Hepatology 1998; 27:228-39. [PMID: 9425942 DOI: 10.1002/hep.510270135] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hepatitis B virus-encoded X antigen contributes to the development of hepatocellular carcinoma. Given that X antigen functions by binding to other proteins, additional X-binding proteins were sought from an adult human liver cDNA library in a yeast two-hybrid system. The results yielded a clone encoding a 55-kd protein that is associated with replicative senescence (p55sen). Binding of p55sen to X antigen was confirmed in vitro by immunoprecipitation and affinity chromatography. The expression of endogenous p55sen inversely correlated with cell growth. Transient transfection of X antigen or p55sen into HepG2 cells stimulated DNA synthesis by twofold to threefold, whereas cotransfection did not, suggesting that these molecules functionally interact. The detection of p55sen in embryonic mouse liver, its absence in adult mouse and human livers, and its reappearance in livers from carriers with chronic liver disease, suggest that it may play important roles in the regulation of liver cell growth. The similarity between p55sen and a notch ligand, which is involved in cell fate determinations during embryogenesis, implies that the binding of p55sen by X antigen may also contribute to an alteration in cell fate, which is characteristic of carcinogenesis.
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71
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Feitelson MA, Ranganathan PN, Clayton MM, Zhang SM. Partial characterization of the woodchuck tumor suppressor, p53, and its interaction with woodchuck hepatitis virus X antigen in hepatocarcinogenesis. Oncogene 1997; 15:327-36. [PMID: 9233767 DOI: 10.1038/sj.onc.1201203] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Full length cDNAs for p53 were made by reverse transcription-polymerase chain reaction of total RNA from two normal woodchuck livers. Two randomly chosen clones from each liver were sequenced and shown to be identical. This sequence revealed 80% or more identity with p53 sequences from human, monkey, and mouse. The cDNA was translated into a 55 kD protein in vitro that was immunoprecipitated by antibodies to p53. Cotranslation of woodchuck p53 with woodchuck hepatitis virus X antigen, followed by immunoprecipitation suggested X/p53 complex formation. Similar complexes were also immunoprecipitated from extracts of infected liver, but not from uninfected liver. The finding of X/p53 complexes in vivo and in vitro in the woodchuck hepadnavirus system, combined with analogous data with hepatitis B, suggests a common mechanism by which these viruses contribute to hepatocellular transformation.
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72
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Ranganathan PN, Feitelson MA. Direct synthesis of full length p53 cDNA from frozen liver. BIOCHEMISTRY AND MOLECULAR BIOLOGY INTERNATIONAL 1997; 41:861-7. [PMID: 9137815 DOI: 10.1080/15216549700201901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
RNA secondary structures can inhibit efficient first strand synthesis in the construction of cDNA clones. Here we report a procedure that incorporates an initial computer analysis of potential secondary structures in related mRNAs. Then a modified, direct reverse transcription-polymerase chain reaction (RT-PCR) procedure optimized for obtaining a full length cDNA starting from a small amount of frozen tissue, without the need for a library construction, is performed. This modified approach is compared to the gene-specific first strand primer method. In addition, the first strand obtained by each of these methods is amplified using two different types of PCR. The utility of this procedure is demonstrated by the successful synthesis of a full length 1.2 kb p53 cDNA by both methods of PCR, from total RNA isolated from woodchuck liver.
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Feitelson MA, Duan LX. Hepatitis B virus X antigen in the pathogenesis of chronic infections and the development of hepatocellular carcinoma. THE AMERICAN JOURNAL OF PATHOLOGY 1997; 150:1141-57. [PMID: 9094970 PMCID: PMC1858185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Chronic infection with hepatitis B virus is associated with a high incidence of liver diseases, including hepatocellular carcinoma. Hepatitis-B-virus-encoded X antigen (HBxAg) stimulates virus gene expression and replication, which may be important for the establishment and maintenance of the chronic carrier state. Integration of viral DNA encoding HBxAg during chronic infection results in increased X antigen expression. HBxAg overexpression may alter signal transduction pathways important for the regulation of cell growth during hepatocellular regeneration. The finding that HBxAg binds to and inactivates negative growth-regulatory molecules, such as the tumor suppressor p53, suggests additional ways that HBxAg may act in hepatocarcinogenesis. HBxAg may also stimulate the expression of positive growth regulators, such as insulin-like growth factor II and the insulin-like growth factor I receptor. The finding that HBxAg may compromise DNA repair and that it may effect the normal turnover of growth-regulatory molecules in the proteasome may also contribute to its carcinogenic properties. Hence, HBxAg may contribute to the pathogenesis of chronic infection and development of hepatocellular carcinoma in a variety of ways.
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Greenblatt MS, Feitelson MA, Zhu M, Bennett WP, Welsh JA, Jones R, Borkowski A, Harris CC. Integrity of p53 in hepatitis B x antigen-positive and -negative hepatocellular carcinomas. Cancer Res 1997; 57:426-32. [PMID: 9012469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Inactivation of the tumor suppressor p53 seems to be important to the pathogenesis of hepatocellular carcinoma (HCC) associated with chronic hepatitis B virus infection. Although this inactivation may be due to mutations in the p53 gene, recent evidence suggests that the hepatitis B virus-encoded X antigen (HBxAg) binds to and inactivates wild-type p53. Hence, experiments were designed to test the hypothesis that there is a low frequency of p53 mutations in HBxAg-positive HCC. HBxAg and p53 were assayed by immunohistochemistry (IHC) in HCC and nontumor liver from 16 Chinese patients, half of whom were hepatitis B surface antigen carriers. HBxAg was detectable in tumor and/or nontumor cells from all patients by IHC; six of these samples also had detectable p53. To determine whether p53 detection by IHC, and hence stabilization, is associated with mutation, sequencing of p53 exons 5-8 was performed with each patient sample. Wild-type sequences were found in 13 of 16 HBxAg-positive cases (81%). Hence, HBxAg is a common marker of HCC that correlates with the persistence of wild-type p53 among both carriers and noncarriers. The low frequency of p53 mutations in HCC in these patients implies that p53 inactivation may occur predominantly by complex formation with HBxAg.
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Brechot C, Nalpas B, Feitelson MA. Interactions between alcohol and hepatitis viruses in the liver. Clin Lab Med 1996; 16:273-87. [PMID: 8792072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
There is a high frequency of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections among individuals with alcoholic liver disease (ALD) and alcohol-associated hepatocellular carcinoma (HCC), suggesting that these viruses are implicated in the pathogenesis of these diseases. Alcohol may act synergistically by promoting the development and progression of liver disease. The interactions of alcohol with infected hepatocytes and with antiviral immunity may result in altered patterns of virus gene expression and replication, making diagnosis difficult in some cases of ALD and HCC. The potential association of ALD and alcoholic HCC with serologically negative virus variants raises major difficulties in the epidemiologic assessment of cause and effect, providing major challenges for the future.
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