1
|
Abstract
Hepatitis B is a DNA virus affecting hundreds of millions of individuals worldwide. As the clinical sequelae of cirrhosis and hepatocellular cancer are increasingly recognized to be related to viral levels, the impetus increases to offer treatment to those previously not treated. With the development of more robust antivirals with reasonable safety profiles, long-term treatment is becoming more common. The oral nucleos(t)ide analogs have become the preferred first-line therapies for most genotypes of hepatitis B. Five are now available, all with different potencies and resistance profiles. Long-term data spanning several years are now available for most compounds in this arena. This article focuses on the common natural variants and those secondary to nucleos(t)ide therapy, as well as diagnostic methods to detect resistance.
Collapse
Affiliation(s)
- Fred Poordad
- David Geffen School of Medicine at UCLA, Hepatology and Liver Transplantation, Cedars-Sinai Medical Center, Suite 1060, Los Angeles, CA 90048, USA.
| | | |
Collapse
|
2
|
Heindryckx F, Colle I, Van Vlierberghe H. Experimental mouse models for hepatocellular carcinoma research. Int J Exp Pathol 2009; 90:367-86. [PMID: 19659896 DOI: 10.1111/j.1365-2613.2009.00656.x] [Citation(s) in RCA: 278] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Every year almost 500,000 new patients are diagnosed with hepatocellular carcinoma (HCC), a primary malignancy of the liver that is associated with a poor prognosis. Numerous experimental models have been developed to define the pathogenesis of HCC and to test novel drug candidates. This review analyses several mouse models useful for HCC research and points out their advantages and weaknesses. Chemically induced HCC mice models mimic the injury-fibrosis-malignancy cycle by administration of a genotoxic compound alone or, if necessary, followed by a promoting agent. Xenograft models develop HCC by implanting hepatoma cell lines in mice, either ectopically or orthotopically; these models are suitable for drug screening, although extrapolation should be considered with caution as multiple cell lines must always be used. The hollow fibre assay offers a solution for limiting the number of test animals in xenograft research because of the ability for implanting multiple cell lines in one mouse. There is also a broad range of genetically modified mice engineered to investigate the pathophysiology of HCC. Transgenic mice expressing viral genes, oncogenes and/or growth factors allow the identification of pathways involved in hepatocarcinogenesis.
Collapse
Affiliation(s)
- Femke Heindryckx
- Department of Gastroenterology and Hepatology, Ghent University Hospital, 9000 Ghent, Belgium.
| | | | | |
Collapse
|
3
|
Chen Y, Cheng G, Mahato RI. RNAi for treating hepatitis B viral infection. Pharm Res 2007; 25:72-86. [PMID: 18074201 PMCID: PMC2217617 DOI: 10.1007/s11095-007-9504-0] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 11/14/2007] [Indexed: 12/18/2022]
Abstract
Chronic hepatitis B virus (HBV) infection is one of the leading causes of liver cirrhosis and hepatocellular carcinoma (HCC). Current treatment strategies of HBV infection including the use of interferon (IFN)-α and nucleotide analogues such as lamivudine and adefovir have met with only partial success. Therefore, it is necessary to develop more effective antiviral therapies that can clear HBV infection with fewer side effects. RNA interference (RNAi), by which a small interfering RNA (siRNA) induces the gene silence at a post-transcriptional level, has the potential of treating HBV infection. The successful use of chemically synthesized siRNA, endogenous expression of small hairpin RNA (shRNA) or microRNA (miRNA) to silence the target gene make this technology towards a potentially rational therapeutics for HBV infection. However, several challenges including poor siRNA stability, inefficient cellular uptake, widespread biodistribution and non-specific effects need to be overcome. In this review, we discuss several strategies for improving the anti-HBV therapeutic efficacy of siRNAs, while avoiding their off-target effects and immunostimulation. There is an in-depth discussion on the (1) mechanisms of RNAi, (2) methods for siRNA/shRNA production, (3) barriers to RNAi-based therapies, and (4) delivery strategies of siRNA for treating HBV infection.
Collapse
Affiliation(s)
- Yong Chen
- Huai-An 4th People’s Hospital, Jiangsu, China
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, 19 S Manassas Street, Memphis, Tennessee 38103 USA
| | - Guofeng Cheng
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, 19 S Manassas Street, Memphis, Tennessee 38103 USA
| | - Ram I. Mahato
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, 19 S Manassas Street, Memphis, Tennessee 38103 USA
| |
Collapse
|
4
|
Shire NJ, Rouster SD, Stanford SD, Blackard JT, Martin CM, Fichtenbaum CJ, Sherman KE. The prevalence and significance of occult hepatitis B virus in a prospective cohort of HIV-infected patients. J Acquir Immune Defic Syndr 2007; 44:309-14. [PMID: 17159656 DOI: 10.1097/qai.0b013e31802e29a9] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Occult hepatitis B virus (HBV) is defined as low-level HBV DNA without hepatitis B surface antigen (HBsAg). Prevalence estimates vary widely. We determined the prevalence of occult HBV at the University of Cincinnati Infectious Diseases Center (IDC). METHODS Patients in the IDC HIV database (n = 3867) were randomly selected using a 25% sampling fraction. Samples were pooled for HBV nucleic acid extraction. Pools were tested for HBV DNA by a real-time polymerase chain reaction (PCR) assay to co-amplify core/surface protein regions. The PCR assay was run on all individual samples from each DNA pool. DNA samples were tested for HBV serologic markers. RESULTS A total of 909 patients without known HBV were selected. The mean CD4 count was 384 cells/mm. Forty-three patients were HBV DNA. Twelve of 43 were DNA/HBsAg (95% confidence interval for database: 0.58% to 1.90%). Five of 12 were negative for all serologic markers. Alanine aminotransferase, aspartate aminotransferase, and HBV DNA titers were elevated in HBsAg patients versus occult patients and versus HIV-monoinfected patients. No other significant differences were detected. No occult HBV patient was on treatment with anti-HBV activity. CONCLUSIONS Forty-three percent of those with HBV were not previously identified as HBV, indicating the need for ongoing screening in high-risk populations. Occult HBV may occur in persons with all negative serologic markers, representing a challenge for identification.
Collapse
Affiliation(s)
- Norah J Shire
- Division of Digestive Diseases, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267, USA.
| | | | | | | | | | | | | |
Collapse
|
5
|
Lee ATC, Ren J, Wong ET, Ban KHK, Lee LA, Lee CGL. The hepatitis B virus X protein sensitizes HepG2 cells to UV light-induced DNA damage. J Biol Chem 2005; 280:33525-35. [PMID: 16055925 DOI: 10.1074/jbc.m506628200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Various reports have implicated the virally encoded HBx protein as a cofactor in hepatocarcinogenesis. However, direct evidence of the role of HBx as a promoter of oncogenesis in response to an initiating factor such as DNA damage remains inadequate. Here, we report the effects of HBx in HepG2 cells exposed to UV light-induced DNA damage. HBx expression was found not to affect the morphology, viability, and cell cycle/apoptotic profiles or DNA repair machinery of untreated cells. Nonetheless, upon UV treatment, HBx protein levels increased concomitantly with p53 levels. Both HBx and p53 proteins were found to interact and colocalize primarily in the nucleus. The binding of HBx to p53 modulated (but did not inhibit) the transcriptional activation function of p53. Notably, HBx-expressing cells exhibited increased sensitivity to UV damage, resulting in greater G2/M arrest and apoptosis of these cells. Additionally, these cells displayed a reduced DNA repair capacity in response to UV damage. In conclusion, this work suggests that DNA damage may be an initiating factor in hepatocarcinogenesis and that HBx may act as the promoting factor by inhibiting DNA repair. In hepatitis B virus-infected hepatocytes, a chronic infection may present the opportunity for such a DNA-damaging event to occur, and accumulated errors caused by the inhibition of DNA repair by HBx may result in oncogenesis.
Collapse
Affiliation(s)
- Alvin T C Lee
- Division of Medical Sciences, National Cancer Centre, Singapore 169610, Singapore
| | | | | | | | | | | |
Collapse
|
6
|
de Moura PR, Rui E, de Almeida Gonçalves K, Kobarg J. The cysteine residues of the hepatitis B virus onco-protein HBx are not required for its interaction with RNA or with human p53. Virus Res 2005; 108:121-31. [PMID: 15681062 DOI: 10.1016/j.virusres.2004.08.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2004] [Revised: 08/23/2004] [Accepted: 08/26/2004] [Indexed: 11/28/2022]
Abstract
The hepatitis B virus (HBV) protein HBx has been implicated to induce liver cancer in transgenic mice and transactivates a variety of viral and cellular promoters. The 17 kDa protein HBx consists of 154 amino acids, contains 10 cysteine residues and is translated during the viral infection. It has been shown previously that the HBx protein is able to bind to singlestranded DNA and RNA. This nucleic acid binding activity might be relevant for HBx oncogenic character. Furthermore, HBx has been reported to interact with a series of cellular proteins, especially with transcription factors, including the tumor suppressor protein p53. To evaluate the importance of the cysteine residues in HBx for its interaction with RNA and p53 we expressed full-length HBx-wt as well as several truncated mini-HBx(18-142) proteins with multiple cysteine to serine point mutations as 6xHis fusion proteins in Escherichia coli. Using UV cross-linking assays we demonstrate that all truncated mini-HBx proteins with cysteine/serine point mutations maintained the ability to bind to an AU-38 RNA oligonucleotide. Furthermore, we performed in vitro binding assays of selected HBx mutants with GST-p53, circular dichroism spectroscopic analysis of the mutant HBx protein secondary structure and a p53 based transcription activation assay in yeast cells. In summary, our data suggest that the cysteine residues in the HBx protein are of minor importance for its interaction with both RNA and the p53 protein.
Collapse
Affiliation(s)
- Patricia Ribeiro de Moura
- Centro de Biologia Molecular Estrutural, Laboratório Nacional de Luz Síncrotron, Rua Giuseppe Máximo Scolfaro 10.000, CP 6192, Campinas, SP, CEP 13084-971, Brazil
| | | | | | | |
Collapse
|
7
|
Kaplan DE, Reddy KR. Rising incidence of hepatocellular carcinoma: the role of hepatitis B and C; the impact on transplantation and outcomes. Clin Liver Dis 2003; 7:683-714. [PMID: 14509534 DOI: 10.1016/s1089-3261(03)00060-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatocellular carcinoma caused by hepatitis B and hepatitis C are global scourges but are likely to peak in incidence in the next 2 decades and then decline. Universal vaccination has been effective in stemming the incidence of chronic hepatitis B and early-onset HCC in regions of high endemicity where implemented, but preventive measures in HCV are not yet available. After the attrition of older affected generations, the incidence of HCC will likely decline rapidly. While no vaccine is currently available for hepatitis C, cases are projected to peak and decline because of a marked reduction in transmission as a result of behavioral modification and safeguarding of blood supplies. Until these epidemiologic projections come to pass, management of hepatocellular carcinoma will continue to become a progressively more frequently encountered clinical challenge. Therapy for chronic hepatitis may ameliorate but will not eliminate the development of tumors. The demand for orthotopic liver transplantation will continue to climb, and palliative therapies for non-resectable cases will require studies aimed at optimization of benefit. LDLT may remain an option for high-risk patients affording tumor-free survival for some otherwise terminal patients.
Collapse
Affiliation(s)
- David E Kaplan
- Division of Gastroenterology and Hepatology, University of Pennsylvania School of Medicine, 3 Raydin, 3400 Spruce Street, Philadelphia, PA 19104, USA
| | | |
Collapse
|
8
|
Nag A, Datta A, Yoo K, Bhattacharyya D, Chakrabortty A, Wang X, Slagle BL, Costa RH, Raychaudhuri P. DDB2 induces nuclear accumulation of the hepatitis B virus X protein independently of binding to DDB1. J Virol 2001; 75:10383-92. [PMID: 11581406 PMCID: PMC114612 DOI: 10.1128/jvi.75.21.10383-10392.2001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2001] [Accepted: 07/30/2001] [Indexed: 02/06/2023] Open
Abstract
The hepatitis B virus (HBV) X protein (HBx) is critical for the life cycle of the virus. HBx associates with several host cell proteins including the DDB1 subunit of the damaged-DNA binding protein DDB. Recent studies on the X protein encoded by the woodchuck hepadnavirus have provided correlative evidence indicating that the interaction with DDB1 is important for establishment of infection by the virus. In addition, the interaction with DDB1 has been implicated in the nuclear localization of HBx. Because the DDB2 subunit of DDB is required for the nuclear accumulation of DDB1, we investigated the role of DDB2 in the nuclear accumulation of HBx. Here we show that expression of DDB2 increases the nuclear levels of HBx. Several C-terminal deletion mutants of DDB2 that fail to bind DDB1 are able to associate with HBx, suggesting that DDB2 may associate with HBx independently of binding to DDB1. We also show that DDB2 enhances the nuclear accumulation of HBx independently of binding to DDB1, since a mutant that does not bind DDB1 is able to enhance the nuclear accumulation of HBx. HBV infection is associated with liver pathogenesis. We show that the nuclear levels of DDB1 and DDB2 are tightly regulated in hepatocytes. Studies with regenerating mouse liver indicate that during late G1 phase the nuclear levels of both subunits of DDB are transiently increased, followed by a sharp decrease in S phase. Taken together, these results suggest that DDB1 and DDB2 would participate in the nuclear functions of HBx effectively only during the late-G1 phase of the cell cycle.
Collapse
Affiliation(s)
- A Nag
- Department of Biochemistry and Molecular Biology, University of Illinois at Chicago, Chicago, Illinois 60612, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Abstract
Chronic hepatitis B virus (HBV) infection is a major global cause of hepatocellular carcinoma (HCC). Individuals who are chronic carriers have a greater than 100-fold increased relative risk of developing the tumour. Several mechanisms of HBV-induced HCC have been proposed. Integration of HBV DNA into the genome of hepatocytes occurs commonly, although integration at cellular sites that are important for regulation of hepatocyte proliferation appears to be a rare event. Functions of the HBx protein are also potentially oncogenic. These include transcriptional activation of cellular growth regulatory genes, modulation of apoptosis and inhibition of nucleotide excision repair of damaged cellular DNA. The effects of HBx are mediated by interaction with cellular proteins and activation of cell signalling pathways. Variations in HBV genome sequences may be important in hepatocarcinogenesis, although their significance has not yet been completely elucidated. Necroinflammatory hepatic disease, which often accompanies chronic HBV infection, may contribute indirectly to hepatocyte transformation in a number of ways, including by facilitating HBV DNA integration, predisposing to the acquisition of cellular mutations and generating mutagenic oxygen reactive species. Although HCC is a malignancy with a poor prognosis, the availability of an effective vaccine against HBV infection, and its inclusion in the Expanded Programme of Immunization of many countries, augurs well for the eventual elimination of HBV-associated HCC.
Collapse
Affiliation(s)
- P Arbuthnot
- Department of Molecular Medicine and Haematology and Molecular Hepatology Research Unit, Department of Medicine, University of the Witwatersrand Medical School, 7 York Road, Parktown 2193, South Africa
| | | |
Collapse
|
10
|
Kawai S, Yokosuka O, Imazeki F, Maru Y, Saisho H. State of HBV DNA in HBsAg-negative, anti-HCV-positive hepatocellular carcinoma: existence of HBV DNA possibly as nonintegrated form with analysis by Alu-HBV DNA PCR and conventional HBV PCR. J Med Virol 2001; 64:410-8. [PMID: 11468724 DOI: 10.1002/jmv.1066] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The role of hepatitis B virus (HBV) in carcinogenesis of hepatitis B surface antigen (HBsAg)-negative, anti-hepatitis C virus (anti-HCV)-positive hepatocellular carcinoma (HCC) remains unknown. To investigate the state of HBV DNA in such HCC, HBV DNA was examined by polymerase chain reaction (PCR) between HBV DNA and human Alu sequence (HBV-Alu PCR), which could detect integrated form of HBV DNA only, and by conventional HBV PCR, which could detect both integrated and episomal forms of HBV DNA. In all the 17 HBsAg-positive HCC, HBV DNA was detected by both HBV-Alu PCR method and conventional HBV PCR method. By contrast, in HBsAg-negative, anti-HCV-positive cases, HBV DNA was detected in 10 of 21 (47.6%) by conventional HBV PCR and in none of 21 (0%) by HBV-Alu PCR method. Thus, integrated form of HBV DNA was not found in most HbsAg-negative, anti-HCV-positive HCC in the current study. The role of episomal form of HBV DNA requires further investigation of its involvement in the process of the development of HBsAg-negative, anti-HCV-positive HCC.
Collapse
Affiliation(s)
- S Kawai
- First Department of Medicine, Chiba University School of Medicine, Chiba, Japan
| | | | | | | | | |
Collapse
|
11
|
Wang XW. Microinjection technique used to study functional interaction between p53 and hepatitis B virus X gene in apoptosis. Mol Biotechnol 2001; 18:169-77. [PMID: 11471458 DOI: 10.1385/mb:18:2:169] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Microinjection of expression vectors into cultured cells has been utilized to study functional interaction of p53 and the hepatitis B virus HBx gene in apoptosis. This approach allows us to determine protein-protein interactions in primary cultured human cells at a single cell level, including fibroblasts, mammary epithelial cells, renal epithelial cells, and hepatocytes. In principle, this approach can be used to study functional interaction of p53 and any gene that is either pro- or anti-apoptotic. The use of primary cultured human cells minimizes ambiguous results associated with immortalized or tumorigenic cell lines. Moreover, it is an easy and effective way to introduce genes of interests into primary human cells with defined genetic defects, thereby facilitating the delineation of genetic pathways.
Collapse
Affiliation(s)
- X W Wang
- Liver Carcinogenesis Section, Lab. Human Carcinogenesis, National Cancer Institute, NIH, Bldg. 37, Room 2025, 37 Convent Drive, Bethesda, MD 20892-4255, USA.
| |
Collapse
|
12
|
Abstract
Chronic hepatitis B virus (HBV) infection is a major global cause of hepatocellular carcinoma (HCC). Individuals who are chronic carriers have a greater than 100-fold increased relative risk of developing the tumour. Several mechanisms of HBV-induced HCC have been proposed. Integration of HBV DNA into the genome of hepatocytes occurs commonly, although integration at cellular sites that are important for regulation of hepatocyte proliferation appears to be a rare event. Functions of the HBx protein are also potentially oncogenic. These include transcriptional activation of cellular growth regulatory genes, modulation of apoptosis and inhibition of nucleotide excision repair of damaged cellular DNA. The effects of HBx are mediated by interaction with cellular proteins and activation of cell signalling pathways. Variations in HBV genome sequences may be important in hepatocarcinogenesis, although their significance has not yet been completely elucidated. Necroinflammatory hepatic disease, which often accompanies chronic HBV infection, may contribute indirectly to hepatocyte transformation in a number of ways, including by facilitating HBV DNA integration, predisposing to the acquisition of cellular mutations and generating mutagenic oxygen reactive species. Although HCC is a malignancy with a poor prognosis, the availability of an effective vaccine against HBV infection, and its inclusion in the Expanded Programme of Immunization of many countries, augurs well for the eventual elimination of HBV-associated HCC.
Collapse
Affiliation(s)
- Patrick Arbuthnot
- Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School7 York Road, Parktown 2193, South Africa
- Molecular Hepatology Research Unit, Department of Medicine, University of the Witwatersrand Medical School7 York Road, Parktown 2193, South Africa
| | - Michael Kew
- Molecular Hepatology Research Unit, Department of Medicine, University of the Witwatersrand Medical School7 York Road, Parktown 2193, South Africa
| |
Collapse
|
13
|
Arbuthnot P, Capovilla A, Kew M. Putative role of hepatitis B virus X protein in hepatocarcinogenesis: effects on apoptosis, DNA repair, mitogen-activated protein kinase and JAK/STAT pathways. J Gastroenterol Hepatol 2000; 15:357-68. [PMID: 10824878 DOI: 10.1046/j.1440-1746.2000.02069.x] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chronic infection with hepatitis B virus (HBV) is a major risk factor for the development of hepatocellular carcinoma (HCC). The pathogenesis of HBV-induced malignant transformation is, however, incompletely understood. HBx, the protein encoded by the X open reading frame, is a transcriptional activator that has been implicated in hepatocarcinogenesis. HBx inhibits the function of the tumour suppressor protein p53 in what is thought to be an early event in hepatocyte transformation before the later accumulation of inactivating p53 point mutations. HBx inhibits apoptosis but also exerts pro-apoptotic effects. The effects of HBx on apoptosis may be important not only for the development of HCC but also for the establishment of HBV infection. Further implication of HBx in hepatocyte transformation has been the demonstration that it inhibits the repair of damaged hepatocyte DNA. This effect may be mediated by interaction with p53 or through binding to the damaged DNA binding protein (DDB), which plays an accessory role in nucleotide excision repair. In addition, HBx activates cell signalling cascades involving mitogen-activated protein kinase (MAPK) and Janus family tyrosine kinases (JAK)/signal transducer and activators of transcription (STAT) pathways. The implications of these modulating effects of HBx are not fully understood, but they are likely to have wide-ranging effects on hepatocyte proliferation, apoptosis and the regulation of cell growth checkpoints. The cellular functions ascribed to HBx are unusually diverse, and defining the biologically important role of HBx during HBV replication will go some way to understanding the sequelae of chronic HBV infection.
Collapse
Affiliation(s)
- P Arbuthnot
- Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School, Parktown, South Africa
| | | | | |
Collapse
|
14
|
Abstract
Hepadnaviruses (hepatitis B viruses) cause transient and chronic infections of the liver. Transient infections run a course of several months, and chronic infections are often lifelong. Chronic infections can lead to liver failure with cirrhosis and hepatocellular carcinoma. The replication strategy of these viruses has been described in great detail, but virus-host interactions leading to acute and chronic disease are still poorly understood. Studies on how the virus evades the immune response to cause prolonged transient infections with high-titer viremia and lifelong infections with an ongoing inflammation of the liver are still at an early stage, and the role of the virus in liver cancer is still elusive. The state of knowledge in this very active field is therefore reviewed with an emphasis on past accomplishments as well as goals for the future.
Collapse
Affiliation(s)
- C Seeger
- Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
| | | |
Collapse
|
15
|
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.
Collapse
Affiliation(s)
- Z Lian
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107-6799, USA
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Pontisso P, Belluco C, Bertorelle R, Moliner LD, Chieco-Bianchi L, Nitti D, Lise M, Alberti A. Hepatitis C virus infection associated with human hepatocellular carcinoma. Cancer 1998. [DOI: 10.1002/(sici)1097-0142(19981015)83:8<1489::aid-cncr3>3.0.co;2-q] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
17
|
Su Q, Schröder CH, Hofmann WJ, Otto G, Pichlmayr R, Bannasch P. Expression of hepatitis B virus X protein in HBV-infected human livers and hepatocellular carcinomas. Hepatology 1998; 27:1109-20. [PMID: 9537452 DOI: 10.1002/hep.510270428] [Citation(s) in RCA: 182] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Transactivation of cellular genes and functional inactivation of p53 by the hepatitis B virus (HBV) X gene-encoded protein (HBx) are proposed as alternative mechanisms for induction of hepatocellular carcinomas (HCCs) in chronic HBV infection. Using an immunohistochemical approach, we studied the expression of HBx in 39 explanted livers with HBV-associated disease. Because the data reported previously have been inconsistent, possibly due to the application of different antibodies, we compared results with 5 polyclonal and 6 monoclonal anti-HBx antibodies from five laboratories. Ten of the 11 antibodies reacted with recombinant HBx by Western blotting, but only 1 polyclonal and 2 monoclonal antibodies reacted specifically with HBx in tissue, and were thus suitable for immunohistochemistry. Three other polyclonal antibodies reacted with tissue components in addition to HBx. One polyclonal and 4 monoclonal antibodies did not recognize the HBx in the tissue. HBx was demonstrated in 16 of 30 (53.3%) cirrhotic livers and 10 of 18 (58.8%) HCCs by all specific antibodies. The expression of HBx, among three HBV antigens examined, was found to be preferentially maintained in HCC and the surrounding liver parenchyma, including focal or nodular preneoplastic lesions. However, the immunoreactivity was always limited to the cytoplasm of a small number of parenchymal and neoplastic cells. The role of X gene expression in HBV-associated human hepatocarcinogenesis remains to be established.
Collapse
Affiliation(s)
- Q Su
- Division of Cell Pathology, German Cancer Research Center, Heidelberg
| | | | | | | | | | | |
Collapse
|
18
|
Müller-Pillasch F, Wallrapp C, Bartels K, Varga G, Friess H, Büchler M, Adler G, Gress TM. Cloning of a new Kunitz-type protease inhibitor with a putative transmembrane domain overexpressed in pancreatic cancer. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1395:88-95. [PMID: 9434156 DOI: 10.1016/s0167-4781(97)00129-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In a previous large scale screen for differentially expressed genes in pancreatic cancer, we identified a gene highly overexpressed in cancer encoding a novel putative transmembrane protein with two Kunitz-type serine protease inhibitor domains. The identified gene named kop (Kunitz domain containing protein overexpressed in pancreatic cancer) was assigned to chromosome 19 in the region 19q13.1. Kop was detected at high levels in pancreatic cancer cell lines and was overexpressed in pancreatic cancer tissues as compared to both, normal pancreas and chronic pancreatitis tissues. Being a member of the Kunitz-type serine protease inhibitor family, this new gene may participate in tumour cell invasion and metastasis and in the development of the marked desmoplastic reaction typical for human pancreatic cancer tissues. In this context, the fact that kop has a putative transmembrane domain may have functional implications of particular interest.
Collapse
MESH Headings
- Adenocarcinoma/genetics
- Amino Acid Sequence
- Base Sequence
- Chromosome Mapping
- Chromosomes, Human, Pair 19/genetics
- Cloning, Molecular
- DNA, Complementary/genetics
- DNA, Neoplasm/genetics
- Gene Expression Regulation, Neoplastic/physiology
- Genes, Neoplasm/genetics
- Humans
- Membrane Glycoproteins
- Molecular Sequence Data
- Organ Specificity
- Pancreas/chemistry
- Pancreatic Neoplasms/chemistry
- Pancreatic Neoplasms/genetics
- RNA, Messenger/analysis
- RNA, Neoplasm/analysis
- Sequence Analysis, DNA
- Serine Proteinase Inhibitors/genetics
- Trypsin Inhibitor, Kunitz Soybean/genetics
- Tumor Cells, Cultured
Collapse
|
19
|
Sandler B, Grofova M, Smirnoff P, Zusman R, Zusman I. Expression of p53 protein in rat colon cancer cell lines transfected with Rous sarcoma virus-33. Cancer Lett 1997; 121:133-7. [PMID: 9570350 DOI: 10.1016/s0304-3835(97)00345-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Expression of the cytoplasmic soluble form of p53 protein in the different rat colon cancer cell lines transfected and non-transfected with Rous sarcoma virus-33 was studied. Concentrations of the p53 protein were detected by commonly used immunochemical methods after its isolation by affinity chromatography columns with the gel fiberglass membranes. The main component of tumor-associated antigens (TAA) eluted from virus-transfected cells was the 53 kDa protein in its cytoplasmic soluble fraction. The non-virogenic colon cancer cells contain a few proteins and concentration of 53 kDa protein was low. Western immunoblotting revealed that the 53 kDa protein isolated from the cell lyzates studied was distinctly recognized by the p53 MAb. ELISA showed that its concentration was markedly higher in the lyzate obtained from the highly virogenic and tumorigenic R9 cell line compared with the non-virogenic cell line RT1. We concluded that the expression of the p53 protein is related to the viral transfection of cancerous cells. The possible role of this phenomenon in the etiology of cancer is discussed.
Collapse
Affiliation(s)
- B Sandler
- Laboratory of Teratology and Experimental Oncology, Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel
| | | | | | | | | |
Collapse
|
20
|
Uchida T, Saitoh T, Shinzawa H. Mutations of the X region of hepatitis B virus and their clinical implications. Pathol Int 1997; 47:183-93. [PMID: 9103208 DOI: 10.1111/j.1440-1827.1997.tb04479.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nucleotide (nt) sequences of the X region of more than 130 hepatitis B virus (HBV) isolates were determined and derived from patients with a variety of clinical features. Correlation of nt substitutions with clinicopathological characteristics was attempted. The X region (465nt) is crucial for the replication and expression of HBV because the X protein transactivates the HBV genes and this region contains the core promoter, enhancer II, and two direct repeats. There are several mutational hotspots, some of which seem to relate to immunological epitopes of the X protein. Two kinds of mutations which have important clinical significances were found. One is an 8-nt deletion between nt 1770 and 1777, which truncates 20 amino acids from the carboxyl terminus of the X protein. This deletion leads to the suppression of replication and expression of HBV DNA, resulting in immunoserological marker (HBsAg) negativity. This silent HBV infection is responsible for the majority of non-A to non-E hepatitis. The other mutation substituting T for C (nt 1655), T for A (nt 1764) and A for G (nt 1766) seems to relate to fulminant hepatitis. Further sequencing studies and in vitro mutagenesis experiments will clarify the significance of other mutations of the X region.
Collapse
Affiliation(s)
- T Uchida
- Department of Pathology, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan
| | | | | |
Collapse
|