|
1
|
Choudhary HB, Mandlik SK, Mandlik DS. Role of p53 suppression in the pathogenesis of hepatocellular carcinoma. World J Gastrointest Pathophysiol 2023; 14:46-70. [PMID: 37304923 PMCID: PMC10251250 DOI: 10.4291/wjgp.v14.i3.46] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/19/2023] [Accepted: 05/31/2023] [Indexed: 06/01/2023] Open
Abstract
In the world, hepatocellular carcinoma (HCC) is among the top 10 most prevalent malignancies. HCC formation has indeed been linked to numerous etiological factors, including alcohol usage, hepatitis viruses and liver cirrhosis. Among the most prevalent defects in a wide range of tumours, notably HCC, is the silencing of the p53 tumour suppressor gene. The control of the cell cycle and the preservation of gene function are both critically important functions of p53. In order to pinpoint the core mechanisms of HCC and find more efficient treatments, molecular research employing HCC tissues has been the main focus. Stimulated p53 triggers necessary reactions that achieve cell cycle arrest, genetic stability, DNA repair and the elimination of DNA-damaged cells’ responses to biological stressors (like oncogenes or DNA damage). To the contrary hand, the oncogene protein of the murine double minute 2 (MDM2) is a significant biological inhibitor of p53. MDM2 causes p53 protein degradation, which in turn adversely controls p53 function. Despite carrying wt-p53, the majority of HCCs show abnormalities in the p53-expressed apoptotic pathway. High p53 in-vivo expression might have two clinical impacts on HCC: (1) Increased levels of exogenous p53 protein cause tumour cells to undergo apoptosis by preventing cell growth through a number of biological pathways; and (2) Exogenous p53 makes HCC susceptible to various anticancer drugs. This review describes the functions and primary mechanisms of p53 in pathological mechanism, chemoresistance and therapeutic mechanisms of HCC.
Collapse
Affiliation(s)
- Heena B Choudhary
- Department of Pharmacology, BVDU, Poona College of Pharmacy, Pune 411038, Maharashtra, India
| | - Satish K Mandlik
- Department of Pharmaceutics, BVDU, Poona College of Pharmacy, Pune 411038, Maharashtra, India
| | - Deepa S Mandlik
- Department of Pharmacology, BVDU, Poona College of Pharmacy, Pune 411038, Maharashtra, India
| |
Collapse
|
|
2
|
Kouroumalis E, Tsomidis I, Voumvouraki A. Pathogenesis of Hepatocellular Carcinoma: The Interplay of Apoptosis and Autophagy. Biomedicines 2023; 11:1166. [PMID: 37189787 PMCID: PMC10135776 DOI: 10.3390/biomedicines11041166] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/09/2023] [Accepted: 04/12/2023] [Indexed: 05/17/2023] Open
Abstract
The pathogenesis of hepatocellular carcinoma (HCC) is a multifactorial process that has not yet been fully investigated. Autophagy and apoptosis are two important cellular pathways that are critical for cell survival or death. The balance between apoptosis and autophagy regulates liver cell turnover and maintains intracellular homeostasis. However, the balance is often dysregulated in many cancers, including HCC. Autophagy and apoptosis pathways may be either independent or parallel or one may influence the other. Autophagy may either inhibit or promote apoptosis, thus regulating the fate of the liver cancer cells. In this review, a concise overview of the pathogenesis of HCC is presented, with emphasis on new developments, including the role of endoplasmic reticulum stress, the implication of microRNAs and the role of gut microbiota. The characteristics of HCC associated with a specific liver disease are also described and a brief description of autophagy and apoptosis is provided. The role of autophagy and apoptosis in the initiation, progress and metastatic potential is reviewed and the experimental evidence indicating an interplay between the two is extensively analyzed. The role of ferroptosis, a recently described specific pathway of regulated cell death, is presented. Finally, the potential therapeutic implications of autophagy and apoptosis in drug resistance are examined.
Collapse
Affiliation(s)
- Elias Kouroumalis
- Department of Gastroenterology, PAGNI University Hospital, University of Crete School of Medicine, 71500 Heraklion, Crete, Greece
- Laboratory of Gastroenterology and Hepatology, University of Crete Medical School, 71500 Heraklion, Crete, Greece
| | - Ioannis Tsomidis
- Laboratory of Gastroenterology and Hepatology, University of Crete Medical School, 71500 Heraklion, Crete, Greece
- 1st Department of Internal Medicine, AHEPA University Hospital, 54621 Thessaloniki, Central Macedonia, Greece
| | - Argyro Voumvouraki
- 1st Department of Internal Medicine, AHEPA University Hospital, 54621 Thessaloniki, Central Macedonia, Greece
| |
Collapse
|
|
3
|
Malekshahi A, Alamdary A, Safarzadeh A, Khavandegar A, Nikoo HR, Safavi M, Ajorloo M, Bahavar A, Ajorloo M. Potential roles of core and core+1 proteins during the chronic phase of hepatitis C virus infection. Future Virol 2023. [DOI: 10.2217/fvl-2022-0117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
The HCV Core protein is a multifunctional protein that interacts with many viral and cellular proteins. In addition to the encapsidation of the viral genome, it can disturb various cellular pathways and impede antiviral cellular responses such as interferon (IFN) production. The Core protein can also disrupt the functions of immune cells against HCV. The Core protein helps viral infection persistency by interfering with apoptosis. The Core+1 protein plays a significant role in inducing chronic HCV infection through diverse mechanisms. We review some of the mechanisms by which Core and Core+1 proteins facilitate HCV infection to chronic infection. These proteins could be considered for designing more sufficient treatments and effective vaccines against HCV.
Collapse
Affiliation(s)
- Asra Malekshahi
- Student Research Committee, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Ashkan Alamdary
- Department of Biology, Science & Research Branch, Islamic Azad University, Tehran, Iran
| | - Ali Safarzadeh
- Department of Biology, University of Padova, Padova, Italy
| | - Armin Khavandegar
- Student Research Committee, Alborz University of Medical Sciences, Karaj, Iran
| | - Hadi Razavi Nikoo
- Infectious Disease Research Center, Golestan University of Medical Sciences, Gorgan, Iran
- Department of Microbiology, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran
| | - Mahshid Safavi
- Student Research Committee, Alborz University of Medical Sciences, Karaj, Iran
| | - Mobina Ajorloo
- Student Research Committee, Alborz University of Medical Sciences, Karaj, Iran
| | - Atefeh Bahavar
- Department of Microbiology, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran
| | - Mehdi Ajorloo
- Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| |
Collapse
|
|
4
|
Association Between Chronic Hepatitis C Virus Infection and Esophageal Cancer: A Systematic Review and Meta-analysis. J Clin Gastroenterol 2022; 56:55-63. [PMID: 33780211 DOI: 10.1097/mcg.0000000000001532] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 02/15/2021] [Indexed: 12/24/2022]
Abstract
BACKGROUND Chronic hepatitis C virus (HCV) infection is associated with increased risk of hepatobiliary tract cancer. However, whether chronic HCV infection is also associated with elevated risk of other types of cancer is still unknown. This systematic review and meta-analysis was conducted in order to investigate whether chronic HCV infection is positively associated with esophageal cancer. METHODS A systematic review was conducted using Embase and MEDLINE databases from inception to November 2019, with a search strategy that comprised the terms for "hepatitis C virus" and "cancer." Eligible studies were cohort studies consisting of patients with chronic HCV infection and comparators without HCV infection, and followed them for incident esophageal cancer. Hazard risk ratio, incidence rate ratio, relative risk or standardized incidence ratio of this association were extracted from each eligible study along with their 95% confidence intervals and were combined to calculate the pooled effect estimate using the random effect, generic inverse variance method. RESULTS A total of 20,459 articles were identified using this search strategy. After 2 rounds of independent review, 7 studies satisfied the inclusion criteria and were included in the meta-analysis. Chronic HCV infection was significantly associated with a higher incidence of esophageal cancer with the pooled relative risk of 1.61 (95% confidence interval: 1.19-2.17; I2=39%). The funnel plot was relatively symmetric which was not suggestive of publication bias. CONCLUSION This systematic review and meta-analysis demonstrated that there is a modest association between chronic HCV and incident esophageal cancer. However, more studies are needed to investigate the causality of this association.
Collapse
|
|
5
|
D'souza S, Lau KCK, Coffin CS, Patel TR. Molecular mechanisms of viral hepatitis induced hepatocellular carcinoma. World J Gastroenterol 2020; 26:5759-5783. [PMID: 33132633 PMCID: PMC7579760 DOI: 10.3748/wjg.v26.i38.5759] [Citation(s) in RCA: 146] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/03/2020] [Accepted: 09/17/2020] [Indexed: 02/06/2023] Open
Abstract
Chronic infection with viral hepatitis affects half a billion individuals worldwide and can lead to cirrhosis, cancer, and liver failure. Liver cancer is the third leading cause of cancer-associated mortality, of which hepatocellular carcinoma (HCC) represents 90% of all primary liver cancers. Solid tumors like HCC are complex and have heterogeneous tumor genomic profiles contributing to complexity in diagnosis and management. Chronic infection with hepatitis B virus (HBV), hepatitis delta virus (HDV), and hepatitis C virus (HCV) are the greatest etiological risk factors for HCC. Due to the significant role of chronic viral infection in HCC development, it is important to investigate direct (viral associated) and indirect (immune-associated) mechanisms involved in the pathogenesis of HCC. Common mechanisms used by HBV, HCV, and HDV that drive hepatocarcinogenesis include persistent liver inflammation with an impaired antiviral immune response, immune and viral protein-mediated oxidative stress, and deregulation of cellular signaling pathways by viral proteins. DNA integration to promote genome instability is a feature of HBV infection, and metabolic reprogramming leading to steatosis is driven by HCV infection. The current review aims to provide a brief overview of HBV, HCV and HDV molecular biology, and highlight specific viral-associated oncogenic mechanisms and common molecular pathways deregulated in HCC, and current as well as emerging treatments for HCC.
Collapse
Affiliation(s)
- Simmone D'souza
- Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary T2N 1N4, AB, Canada
| | - Keith CK Lau
- Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary T2N 1N4, AB, Canada
| | - Carla S Coffin
- Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary T2N 1N4, AB, Canada
| | - Trushar R Patel
- Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary T2N 1N4, AB, Canada
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge T1K3M4, AB, Canada
| |
Collapse
|
|
6
|
Cortactin Interacts with Hepatitis C Virus Core and NS5A Proteins: Implications for Virion Assembly. J Virol 2020; 94:JVI.01306-20. [PMID: 32727880 DOI: 10.1128/jvi.01306-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 07/17/2020] [Indexed: 12/11/2022] Open
Abstract
Hepatitis C virus (HCV) exploits cellular proteins to facilitate viral propagation. To identify the cellular factors involved in the HCV life cycle, we previously performed protein microarray assays using either HCV nonstructural 5A (NS5A) protein or core protein as a probe. Interestingly, cellular cortactin strongly interacted with both NS5A and core. Cortactin is an actin-binding protein critically involved in tumor progression by regulating the migration and invasion of cancerous cells. Protein interaction between cortactin and NS5A or core was confirmed by coimmunoprecipitation and immunofluorescence assays. We showed that cortactin interacted with NS5A and core via the N-terminal acidic domain of cortactin. Cortactin expression levels were not altered by HCV infection. Small interfering RNA (siRNA)-mediated knockdown of cortactin dramatically decreased HCV protein expression and infectivity levels, whereas overexpression of cortactin increased viral propagation. Ectopic expression of the siRNA-resistant cortactin recovered the viral infectivity, suggesting that cortactin was specifically required for HCV propagation. We further showed that cortactin was involved in the assembly step without affecting viral entry, HCV internal ribosome entry site (IRES)-mediated translation, and the replication steps of the HCV life cycle. Of note, silencing of cortactin markedly reduced both NS5A and core protein levels on the lipid droplets (LDs), and this effect was reversed by the overexpression of cortactin. Importantly, NS5A and core promoted cell migration by activating the phosphorylation of cortactin at tyrosine residues 421 and 466. Taken together, these data suggest that cortactin is not only involved in HCV assembly but also plays an important role in the cell migration.IMPORTANCE Cortactin is a cytoskeletal protein that regulates cell migration in response to a number of extracellular stimuli. The functional involvement of cortactin in the virus life cycle is not yet fully understood. The most significant finding is that cortactin strongly interacted with both hepatitis C virus (HCV) core and NS5A. Cortactin is involved in HCV assembly by tethering core and NS5A on the lipid droplets (LDs) with no effect on LD biogenesis. It was noteworthy that HCV NS5A and core activated cortactin by phosphorylation at tyrosines 421 and 466 to regulate cell migration. Collectively, our study shows that cortactin is a novel host factor involved in viral production and HCV-associated pathogenesis.
Collapse
|
|
7
|
Ponvilawan B, Charoenngam N, Rujirachun P, Wattanachayakul P, Tornsatitkul S, Rittiphairoj T, Ungprasert P. Chronic Hepatitis C Virus Infection is Associated with an Increased Risk of Lung Cancer: A Systematic Review and Meta-analysis. Lung 2020; 198:705-714. [DOI: 10.1007/s00408-020-00365-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/27/2020] [Indexed: 12/24/2022]
|
|
8
|
Vescovo T, Pagni B, Piacentini M, Fimia GM, Antonioli M. Regulation of Autophagy in Cells Infected With Oncogenic Human Viruses and Its Impact on Cancer Development. Front Cell Dev Biol 2020; 8:47. [PMID: 32181249 PMCID: PMC7059124 DOI: 10.3389/fcell.2020.00047] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 01/20/2020] [Indexed: 12/14/2022] Open
Abstract
About 20% of total cancer cases are associated to infections. To date, seven human viruses have been directly linked to cancer development: high-risk human papillomaviruses (hrHPVs), Merkel cell polyomavirus (MCPyV), hepatitis B virus (HBV), hepatitis C virus (HCV), Epstein–Barr virus (EBV), Kaposi’s sarcoma-associated herpesvirus (KSHV), and human T-lymphotropic virus 1 (HTLV-1). These viruses impact on several molecular mechanisms in the host cells, often resulting in chronic inflammation, uncontrolled proliferation, and cell death inhibition, and mechanisms, which favor viral life cycle but may indirectly promote tumorigenesis. Recently, the ability of oncogenic viruses to alter autophagy, a catabolic process activated during the innate immune response to infections, is emerging as a key event for the onset of human cancers. Here, we summarize the current understanding of the molecular mechanisms by which human oncogenic viruses regulate autophagy and how this negative regulation impacts on cancer development. Finally, we highlight novel autophagy-related candidates for the treatment of virus-related cancers.
Collapse
Affiliation(s)
- Tiziana Vescovo
- National Institute for Infectious Diseases "Lazzaro Spallanzani" - IRCCS, Rome, Italy
| | - Benedetta Pagni
- National Institute for Infectious Diseases "Lazzaro Spallanzani" - IRCCS, Rome, Italy.,Department of Biology, University of Rome "Tor Vergata," Rome, Italy
| | - Mauro Piacentini
- National Institute for Infectious Diseases "Lazzaro Spallanzani" - IRCCS, Rome, Italy.,Department of Biology, University of Rome "Tor Vergata," Rome, Italy
| | - Gian Maria Fimia
- National Institute for Infectious Diseases "Lazzaro Spallanzani" - IRCCS, Rome, Italy.,Department of Molecular Medicine, University of Rome "Sapienza," Rome, Italy
| | - Manuela Antonioli
- National Institute for Infectious Diseases "Lazzaro Spallanzani" - IRCCS, Rome, Italy
| |
Collapse
|
|
9
|
Gallo A, Miele M, Badami E, Conaldi PG. Molecular and cellular interplay in virus-induced tumors in solid organ recipients. Cell Immunol 2019. [DOI: 10.1016/j.cellimm.2018.02.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
|
10
|
Molecular Mechanisms Driving Progression of Liver Cirrhosis towards Hepatocellular Carcinoma in Chronic Hepatitis B and C Infections: A Review. Int J Mol Sci 2019. [PMID: 30889843 DOI: 10.3390/ijms] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Almost all patients with hepatocellular carcinoma (HCC), a major type of primary liver cancer, also have liver cirrhosis, the severity of which hampers effective treatment for HCC despite recent progress in the efficacy of anticancer drugs for advanced stages of HCC. Here, we review recent knowledge concerning the molecular mechanisms of liver cirrhosis and its progression to HCC from genetic and epigenomic points of view. Because ~70% of patients with HCC have hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infection, we focused on HBV- and HCV-associated HCC. The literature suggests that genetic and epigenetic factors, such as microRNAs, play a role in liver cirrhosis and its progression to HCC, and that HBV- and HCV-encoded proteins appear to be involved in hepatocarcinogenesis. Further studies are needed to elucidate the mechanisms, including immune checkpoints and molecular targets of kinase inhibitors, associated with liver cirrhosis and its progression to HCC.
Collapse
|
|
11
|
Molecular Mechanisms Driving Progression of Liver Cirrhosis towards Hepatocellular Carcinoma in Chronic Hepatitis B and C Infections: A Review. Int J Mol Sci 2019; 20:ijms20061358. [PMID: 30889843 PMCID: PMC6470669 DOI: 10.3390/ijms20061358] [Citation(s) in RCA: 183] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 02/23/2019] [Accepted: 03/14/2019] [Indexed: 02/07/2023] Open
Abstract
Almost all patients with hepatocellular carcinoma (HCC), a major type of primary liver cancer, also have liver cirrhosis, the severity of which hampers effective treatment for HCC despite recent progress in the efficacy of anticancer drugs for advanced stages of HCC. Here, we review recent knowledge concerning the molecular mechanisms of liver cirrhosis and its progression to HCC from genetic and epigenomic points of view. Because ~70% of patients with HCC have hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infection, we focused on HBV- and HCV-associated HCC. The literature suggests that genetic and epigenetic factors, such as microRNAs, play a role in liver cirrhosis and its progression to HCC, and that HBV- and HCV-encoded proteins appear to be involved in hepatocarcinogenesis. Further studies are needed to elucidate the mechanisms, including immune checkpoints and molecular targets of kinase inhibitors, associated with liver cirrhosis and its progression to HCC.
Collapse
|
|
12
|
Villani R, Vendemiale G, Serviddio G. Molecular Mechanisms Involved in HCC Recurrence after Direct-Acting Antiviral Therapy. Int J Mol Sci 2018; 20:ijms20010049. [PMID: 30583555 PMCID: PMC6337751 DOI: 10.3390/ijms20010049] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 12/14/2022] Open
Abstract
Chronic hepatitis C is associated with a high risk of developing hepatocellular carcinoma (HCC) because of a direct effect of the Hepatitis C Virus (HCV) proteins and an indirect oncogenic effect of chronic inflammation and impaired immune response. The treatment of chronic hepatitis C markedly reduces all-cause mortality; in fact, interferon-based treatment has shown a reduction of HCC incidence of more than 70%. The recent introduction of the highly effective direct-acting antivirals (DAAs) has completely changed the scenario of chronic hepatitis C (CHC) with rates of HCV cure over 90%. However, an unexpectedly high incidence of HCC recurrence was observed in patients after DAA treatment (27% versus 0.4–2% in patients who received interferon treatment). The mechanism that underlies the high rate of tumor relapse is currently unknown and is one of the main issues in hepatology. We reviewed the possible mechanisms involved in HCC recurrence after DAA treatment.
Collapse
MESH Headings
- Animals
- Antiviral Agents/therapeutic use
- Carcinoma, Hepatocellular/drug therapy
- Carcinoma, Hepatocellular/epidemiology
- Carcinoma, Hepatocellular/immunology
- Carcinoma, Hepatocellular/virology
- Hepacivirus/drug effects
- Hepacivirus/immunology
- Hepatitis C, Chronic/drug therapy
- Hepatitis C, Chronic/epidemiology
- Hepatitis C, Chronic/immunology
- Hepatitis C, Chronic/virology
- Humans
- Incidence
- Interferons/therapeutic use
- Liver Neoplasms/drug therapy
- Liver Neoplasms/epidemiology
- Liver Neoplasms/immunology
- Liver Neoplasms/virology
- Macrophages/drug effects
- Monocytes/drug effects
- Neoplasm Recurrence, Local/drug therapy
- Neoplasm Recurrence, Local/epidemiology
- Neoplasm Recurrence, Local/immunology
- Neoplasm Recurrence, Local/virology
- Neutrophils/drug effects
Collapse
Affiliation(s)
- Rosanna Villani
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Department of Medical and Surgical Sciences, Institute of Internal Medicine, University of Foggia, 71122 Foggia, Italy.
| | - Gianluigi Vendemiale
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Department of Medical and Surgical Sciences, Institute of Internal Medicine, University of Foggia, 71122 Foggia, Italy.
| | - Gaetano Serviddio
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Department of Medical and Surgical Sciences, Institute of Internal Medicine, University of Foggia, 71122 Foggia, Italy.
| |
Collapse
|
|
13
|
Molecular Mechanisms of Hepatocarcinogenesis Following Sustained Virological Response in Patients with Chronic Hepatitis C Virus Infection. Viruses 2018; 10:v10100531. [PMID: 30274202 PMCID: PMC6212901 DOI: 10.3390/v10100531] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/25/2018] [Accepted: 09/27/2018] [Indexed: 02/07/2023] Open
Abstract
Despite the success of direct-acting antiviral (DAA) agents in treating chronic hepatitis C virus (HCV) infection, the number of cases of HCV-related hepatocellular carcinoma (HCC) is expected to increase over the next five years. HCC develops over the span of decades and is closely associated with fibrosis stage. HCV both directly and indirectly establishes a pro-inflammatory environment favorable for viral replication. Repeated cycles of cell death and regeneration lead to genomic instability and loss of cell cycle control. DAA therapy offers >90% sustained virological response (SVR) rates with fewer side effects and restrictions than interferon. While elimination of HCV helps to restore liver function and reverse mild fibrosis, post-SVR patients remain at elevated risk of HCC. A series of studies reporting higher than expected rates of HCC development among DAA-treated patients ignited debate over whether use of DAAs elevates HCC risk compared to interferon. However, recent prospective and retrospective studies based on larger patient cohorts have found no significant difference in risk between DAA and interferon therapy once other factors are taken into account. Although many mechanisms and pathways involved in hepatocarcinogenesis have been elucidated, our understanding of drivers specific to post-SVR hepatocarcinogenesis is still limited, and lack of suitable in vivo and in vitro experimental systems has hampered efforts to examine etiology-specific mechanisms that might serve to answer this question more thoroughly. Further research is needed to identify risk factors and biomarkers for post-SVR HCC and to develop targeted therapies based on more complete understanding of the molecules and pathways implicated in hepatocarcinogenesis.
Collapse
|
|
14
|
Abstract
Liver cancer remains one of the most common human cancers with a high mortality rate. Therapies for hepatocellular carcinoma (HCC) remain ineffective, due to the heterogeneity of HCC with regard to both the etiology and mutation spectrum, as well as its chemotherapy resistant nature; thus surgical resection and liver transplantation remain the gold standard of patient care. The most common etiologies of HCC are extrinsic factors. Humans have multiple defense mechanisms against extrinsic factor-induced carcinogenesis, of which tumor suppressors play crucial roles in preventing normal cells from becoming cancerous. The tumor suppressor p53 is one of the most frequently mutated genes in liver cancer. p53 regulates expression of genes involved in cell cycle progression, cell death, and cellular metabolism to avert tumor development due to carcinogens. This review article mainly summarizes extrinsic factors that induce liver cancer and potentially have etiological association with p53, including aflatoxin B1, vinyl chloride, non-alcoholic fatty liver disease, iron overload, and infection of hepatitis viruses.
Collapse
Affiliation(s)
- Tim Link
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Tomoo Iwakuma
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| |
Collapse
|
|
15
|
Molecular mechanisms of hepatitis C virus-induced hepatocellular carcinoma. Clin Microbiol Infect 2016; 22:853-861. [PMID: 27476823 DOI: 10.1016/j.cmi.2016.07.019] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 07/09/2016] [Accepted: 07/16/2016] [Indexed: 02/06/2023]
Abstract
Hepatitis C virus (HCV) is a major leading cause of hepatocellular carcinoma (HCC). HCV-induced hepatocarcinogenesis is a multistep process resulting from a combination of pathway alterations that are either caused directly by viral factors or immune mediated as a consequence of a chronic state of inflammation. Host genetic variation is now emerging as an additional element that contribute to increase the risk of developing HCC. The advent of direct-acting antiviral agents foresees a rapid decline of HCC rate in HCV patients. However, a full understanding of the HCV-mediated tumourigenic process is required to elucidate if pro-oncogenic signatures may persist after virus clearance, and to identify novel tools for HCC prevention and therapy. In this review, we summarize the current knowledge of the molecular mechanisms responsible for HCV-induced hepatocarcinogenesis.
Collapse
|
|
16
|
Popik OV, Petrovskiy ED, Mishchenko EL, Lavrik IN, Ivanisenko VA. Mosaic gene network modelling identified new regulatory mechanisms in HCV infection. Virus Res 2015; 218:71-8. [PMID: 26481968 DOI: 10.1016/j.virusres.2015.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Revised: 09/25/2015] [Accepted: 10/02/2015] [Indexed: 10/22/2022]
Abstract
Modelling of gene networks is widely used in systems biology to study the functioning of complex biological systems. Most of the existing mathematical modelling techniques are useful for analysis of well-studied biological processes, for which information on rates of reactions is available. However, complex biological processes such as those determining the phenotypic traits of organisms or pathological disease processes, including pathogen-host interactions, involve complicated cross-talk between interacting networks. Furthermore, the intrinsic details of the interactions between these networks are often missing. In this study, we developed an approach, which we call mosaic network modelling, that allows the combination of independent mathematical models of gene regulatory networks and, thereby, description of complex biological systems. The advantage of this approach is that it allows us to generate the integrated model despite the fact that information on molecular interactions between parts of the model (so-called mosaic fragments) might be missing. To generate a mosaic mathematical model, we used control theory and mathematical models, written in the form of a system of ordinary differential equations (ODEs). In the present study, we investigated the efficiency of this method in modelling the dynamics of more than 10,000 simulated mosaic regulatory networks consisting of two pieces. Analysis revealed that this approach was highly efficient, as the mean deviation of the dynamics of mosaic network elements from the behaviour of the initial parts of the model was less than 10%. It turned out that for construction of the control functional, data on perturbation of one or two vertices of the mosaic piece are sufficient. Further, we used the developed method to construct a mosaic gene regulatory network including hepatitis C virus (HCV) as the first piece and the tumour necrosis factor (TNF)-induced apoptosis and NF-κB induction pathways as the second piece. Thus, the mosaic model integrates the model of HCV subgenomic replicon replication with the model of TNF-induced apoptosis and NF-κB induction. Analysis of the mosaic model revealed that the regulation of TNF-induced signaling by the HCV network is crucially dependent on the RIP1, TRADD, TRAF2, FADD, IKK, IκBα, c-FLIP, and BAR genes. Overall, the developed mosaic gene network modelling approach demonstrated good predictive power and allowed the prediction of new regulatory nodes in HCV action on apoptosis and the NF-κB pathway. Those theoretical predictions could be a basis for further experimental verification.
Collapse
Affiliation(s)
- Olga V Popik
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Prospekt Lavrentyeva 10, Novosibirsk 630090, Russia
| | - Evgeny D Petrovskiy
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Prospekt Lavrentyeva 10, Novosibirsk 630090, Russia; International Tomography Center SB RAS, Institutskaya 3A, Novosibirsk 630090, Russia
| | - Elena L Mishchenko
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Prospekt Lavrentyeva 10, Novosibirsk 630090, Russia
| | - Inna N Lavrik
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Prospekt Lavrentyeva 10, Novosibirsk 630090, Russia; Otto von Guericke University Magdeburg, Medical Faculty, Department Translational Inflammation Research, Pfälzer Platz Building 28, Magdeburg 39106, Germany
| | - Vladimir A Ivanisenko
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Prospekt Lavrentyeva 10, Novosibirsk 630090, Russia; PB-soft, LLC, Novosibirsk, Prospekt Lavrentyeva 10, Novosibirsk 630090, Russia.
| |
Collapse
|
|
17
|
Jiang X, Kanda T, Wu S, Nakamoto S, Nakamura M, Sasaki R, Haga Y, Wakita T, Shirasawa H, Yokosuka O. Hepatitis C Virus Nonstructural Protein 5A Inhibits MG132-Induced Apoptosis of Hepatocytes in Line with NF-κB-Nuclear Translocation. PLoS One 2015; 10:e0131973. [PMID: 26133378 PMCID: PMC4489642 DOI: 10.1371/journal.pone.0131973] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 06/09/2015] [Indexed: 12/21/2022] Open
Abstract
Background Hepatitis C virus (HCV) infection is one of the major causes of cirrhosis and hepatocellular carcinoma. HCV nonstructural protein 5A (NS5A) is an attractive antiviral target and plays an important role in HCV replication as well as hepatocarcinogenesis. The aim of this study was to assess the effect of HCV NS5A protein in the abrogation of apoptotic cell death induced by the proteasome inhibitor MG132. Methods Apoptotic responses to MG132 and the expression of molecules involved in NF-κB signaling pathways in human hepatocytes were investigated with or without the expression of HCV NS5A. Results HCV NS5A protected HepG2 cells against MG132-induced apoptosis, in line with NF-κB-nuclear translocation. A similar NF-κB-nuclear translocation was observed in Huh7 cells infected with HCV JFH1. In agreement with this, after treatment with MG132, HCV NS5A could elevate the transcription of several NF-κB target genes such as BCL2 and BCLXL to inhibit MG132-induced apoptosis in hepatocytes. HCV HCV NS5A also enhanced phosphorylation of IκBα. Consistent with a conferred prosurvival advantage, HCV NS5A reduced MG132-induced poly(adenosine diphosphate-ribose) polymerase cleavage. Conclusions HCV NS5A expression enhances phosphorylation of IκBα, liberates NF-κB for nuclear translocation and downregulates MG132-induced apoptotic pathways in human hepatocytes. It is possible that the disruption of proteasome-associated apoptosis plays a role in the pathogenesis of HCV infection.
Collapse
Affiliation(s)
- Xia Jiang
- Departments of Gastroenterology and Nephrology, Chiba University, Graduate School of Medicine, Chiba, Japan
| | - Tatsuo Kanda
- Departments of Gastroenterology and Nephrology, Chiba University, Graduate School of Medicine, Chiba, Japan
- * E-mail:
| | - Shuang Wu
- Departments of Gastroenterology and Nephrology, Chiba University, Graduate School of Medicine, Chiba, Japan
| | - Shingo Nakamoto
- Departments of Molecular Virology, Chiba University, Graduate School of Medicine, Chiba, Japan
| | - Masato Nakamura
- Departments of Gastroenterology and Nephrology, Chiba University, Graduate School of Medicine, Chiba, Japan
| | - Reina Sasaki
- Departments of Gastroenterology and Nephrology, Chiba University, Graduate School of Medicine, Chiba, Japan
| | - Yuki Haga
- Departments of Gastroenterology and Nephrology, Chiba University, Graduate School of Medicine, Chiba, Japan
| | - Takaji Wakita
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Hiroshi Shirasawa
- Departments of Molecular Virology, Chiba University, Graduate School of Medicine, Chiba, Japan
| | - Osamu Yokosuka
- Departments of Gastroenterology and Nephrology, Chiba University, Graduate School of Medicine, Chiba, Japan
| |
Collapse
|
|
18
|
Emerging roles of interferon-stimulated genes in the innate immune response to hepatitis C virus infection. Cell Mol Immunol 2014; 13:11-35. [PMID: 25544499 PMCID: PMC4712384 DOI: 10.1038/cmi.2014.127] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 11/21/2014] [Accepted: 11/22/2014] [Indexed: 12/14/2022] Open
Abstract
Infection with hepatitis C virus (HCV), a major viral cause of chronic liver disease, frequently progresses to steatosis and cirrhosis, which can lead to hepatocellular carcinoma. HCV infection strongly induces host responses, such as the activation of the unfolded protein response, autophagy and the innate immune response. Upon HCV infection, the host induces the interferon (IFN)-mediated frontline defense to limit virus replication. Conversely, HCV employs diverse strategies to escape host innate immune surveillance. Type I IFN elicits its antiviral actions by inducing a wide array of IFN-stimulated genes (ISGs). Nevertheless, the mechanisms by which these ISGs participate in IFN-mediated anti-HCV actions remain largely unknown. In this review, we first outline the signaling pathways known to be involved in the production of type I IFN and ISGs and the tactics that HCV uses to subvert innate immunity. Then, we summarize the effector mechanisms of scaffold ISGs known to modulate IFN function in HCV replication. We also highlight the potential functions of emerging ISGs, which were identified from genome-wide siRNA screens, in HCV replication. Finally, we discuss the functions of several cellular determinants critical for regulating host immunity in HCV replication. This review will provide a basis for understanding the complexity and functionality of the pleiotropic IFN system in HCV infection. Elucidation of the specificity and the mode of action of these emerging ISGs will also help to identify novel cellular targets against which effective HCV therapeutics can be developed.
Collapse
|
|
19
|
Emerging roles of interferon-stimulated genes in the innate immune response to hepatitis C virus infection. Cell Mol Immunol 2014; 11:218-20. [PMID: 25544499 DOI: 10.1038/cmi.2014.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 01/03/2014] [Accepted: 01/06/2014] [Indexed: 12/16/2022] Open
Abstract
Infection with hepatitis C virus (HCV), a major viral cause of chronic liver disease, frequently progresses to steatosis and cirrhosis, which can lead to hepatocellular carcinoma. HCV infection strongly induces host responses, such as the activation of the unfolded protein response, autophagy and the innate immune response. Upon HCV infection, the host induces the interferon (IFN)-mediated frontline defense to limit virus replication. Conversely, HCV employs diverse strategies to escape host innate immune surveillance. Type I IFN elicits its antiviral actions by inducing a wide array of IFN-stimulated genes (ISGs). Nevertheless, the mechanisms by which these ISGs participate in IFN-mediated anti-HCV actions remain largely unknown. In this review, we first outline the signaling pathways known to be involved in the production of type I IFN and ISGs and the tactics that HCV uses to subvert innate immunity. Then, we summarize the effector mechanisms of scaffold ISGs known to modulate IFN function in HCV replication. We also highlight the potential functions of emerging ISGs, which were identified from genome-wide siRNA screens, in HCV replication. Finally, we discuss the functions of several cellular determinants critical for regulating host immunity in HCV replication. This review will provide a basis for understanding the complexity and functionality of the pleiotropic IFN system in HCV infection. Elucidation of the specificity and the mode of action of these emerging ISGs will also help to identify novel cellular targets against which effective HCV therapeutics can be developed.
Collapse
|
|
20
|
Lin MV, King LY, Chung RT. Hepatitis C virus-associated cancer. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2014; 10:345-70. [PMID: 25387053 DOI: 10.1146/annurev-pathol-012414-040323] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Hepatitis C virus (HCV) is one of the major etiologic agents of liver cancer. HCV is an RNA virus that, unlike hepatitis B virus, is unable to integrate into the host genome. Through complex interactions between viral and host proteins that induce host responses and promote inflammation, fibrosis, and ultimately cirrhosis, HCV infection can result in the development of hepatocellular carcinoma (HCC). The HCV oncogenic process involves genetic and epigenetic alterations and oncogenic effects mediated by viral proteins in the activation of cellular oncogenes, inactivation of tumor-suppressor genes, and dysregulation of multiple signal-transduction pathways. Advances in genetics and gene expression profiling have enhanced our current understanding of the pathways involved in HCV-associated liver cancer development. In this review, we summarize the current understanding of mechanisms of hepatocarcinogenesis induced by HCV infection.
Collapse
Affiliation(s)
- Ming V Lin
- Gastrointestinal Unit, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114; , ,
| | | | | |
Collapse
|
|
21
|
Hoshida Y, Fuchs BC, Bardeesy N, Baumert TF, Chung RT. Pathogenesis and prevention of hepatitis C virus-induced hepatocellular carcinoma. J Hepatol 2014; 61:S79-90. [PMID: 25443348 PMCID: PMC4435677 DOI: 10.1016/j.jhep.2014.07.010] [Citation(s) in RCA: 153] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/03/2014] [Accepted: 07/10/2014] [Indexed: 02/08/2023]
Abstract
Hepatitis C virus (HCV) is one of the major aetiologic agents that causes hepatocellular carcinoma (HCC) by generating an inflammatory, fibrogenic, and carcinogenic tissue microenvironment in the liver. HCV-induced HCC is a rational target for cancer preventive intervention because of the clear-cut high-risk condition, cirrhosis, associated with high cancer incidence (1% to 7% per year). Studies have elucidated direct and indirect carcinogenic effects of HCV, which have in turn led to the identification of candidate HCC chemoprevention targets. Selective molecular targeted agents may enable personalized strategies for HCC chemoprevention. In addition, multiple experimental and epidemiological studies suggest the potential value of generic drugs or dietary supplements targeting inflammation, oxidant stress, or metabolic derangements as possible HCC chemopreventive agents. While the successful use of highly effective direct-acting antiviral agents will make important inroads into reducing long-term HCC risk, there will remain an important role for HCC chemoprevention even after viral cure, given the persistence of HCC risk in persons with advanced HCV fibrosis, as shown in recent studies. The successful development of cancer preventive therapies will be more challenging compared to cancer therapeutics because of the requirement for larger and longer clinical trials and the need for a safer toxicity profile given its use as a preventive agent. Molecular biomarkers to selectively identify high-risk population could help mitigate these challenges. Genome-wide, unbiased molecular characterization, high-throughput drug/gene screening, experimental model-based functional analysis, and systems-level in silico modelling are expected to complement each other to facilitate discovery of new HCC chemoprevention targets and therapies.
Collapse
Affiliation(s)
- Yujin Hoshida
- Liver Cancer Program, Tisch Cancer Institute, Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, United States.
| | - Bryan C Fuchs
- Division of Surgical Oncology, Massachusetts General Hospital, Harvard Medical School, United States
| | - Nabeel Bardeesy
- Cancer Center, Massachusetts General Hospital, Harvard Medical School, United States
| | - Thomas F Baumert
- INSERM Unité 1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Université de Strasbourg, and Institut Hospitalo-Universitaire, Pôle Hépato-digestif, Hôpitaux Universitaires de Strasbourg, France; Liver Center and Gastrointestinal Division, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, United States
| | - Raymond T Chung
- Liver Center and Gastrointestinal Division, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, United States.
| |
Collapse
|
|
22
|
Abstract
Abundant evidence supports the belief of a causal relationship between cirrhosis and hepatocellular carcinoma, but one that differs between high- and low-incidence regions of the tumor. In high-incidence regions, the cirrhosis is of the macronodular variety, is typically asymptomatic, and is caused predominantly by chronic hepatitis B virus infection, whereas in low-incidence regions, the cirrhosis, although usually macronodular, may be micronodular, is commonly symptomatic and of long-standing, and is caused by chronic hepatitis C virus infection, alcohol abuse over many years, the metabolic syndrome, or hereditary hemochromatosis. In a minority of patients, hepatocellular carcinoma develops in the absence of cirrhosis, supporting a direct hepatocarcinogenic effect of some of the causal agents. Cirrhosis is the major risk factor for tumor formation in patients with chronic hepatitis C virus infection. This virus does not integrate into cellular DNA, and malignant transformation results from increased liver cell turnover induced by recurring injury and regeneration of cells in the context of persisting inflammation, oxidative DNA damage, fibrosis, cirrhosis, and changes induced by the virus at a DNA level that have yet to be fully defined. Hepatitis B virus causes malignant transformation by both direct and indirect routes. The direct route results, in part, from integration of the viral DNA into host cellular DNA; transcriptional activation of host growth regulatory genes by hepatitis B virus-encoded proteins; and effects on apoptosis, cell signaling, and DNA repair. The direct route may share some similarities with that of hepatitis C virus infection. The metabolic syndrome may cause malignant transformation by production of oxidative stress and the induction of a variety of mutations, including some in the p53 gene.
Collapse
Affiliation(s)
- Michael C Kew
- Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa,
| |
Collapse
|
|
23
|
Machida K. Tumor-initiating stem-like cells and drug resistance: carcinogenesis through Toll-like receptors, environmental factors, and virus. Drug Deliv Transl Res 2013; 3:152-64. [PMID: 25787983 PMCID: PMC10578060 DOI: 10.1007/s13346-012-0115-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neoplasms contain distinct subpopulations of cells known as tumor-initiating stem-like cells (TICs) that have been identified as key drivers of tumor growth and malignant progression with drug resistance. Stem cells normally proliferate through self-renewing divisions in which the two daughter cells differ markedly in their proliferative potential, with one displaying the differentiation phenotypes and another retaining self-renewing activity. Therefore, understanding the molecular mechanisms of hepatocarcinogenesis will be required for the eventual development of improved therapeutic modalities for treating hepatocellular carcinoma (HCC). Hepatitis C virus (HCV) and hepatitis B virus is a major cause of HCC. Compelling epidemiologic evidence identifies obesity and alcohol as co-morbidity factors that can increase the risk of HCV patients for HCC, especially in alcoholics or obese patients. The mechanisms underlying liver oncogenesis, and how environmental factors contribute to this process, are not yet understood. The HCV-Toll-like receptor 4 (TLR4)-Nanog signaling network is established since alcohol/obesity-associated endotoxemia then activates TLR4 signaling, resulting in the induction of the stem cell marker Nanog expression and liver tumors. Liver TICs are highly sensitized to leptin and exposure of TICs to leptin increases the expression and activity of an intrinsic pluripotency-associated transcriptional network comprised of signal transducer and activator of transcription 3, SOX2, OCT4, and Nanog. Stimulation of the pluripotency network may have significant implications for hepatocellular oncogenesis via genesis and maintenance of TICs. It is important to understand how HCV induces liver cancer through genesis of TICs so that better prevention and treatment can be found. This article reviews the oncogenic pathways to generate TICs.
Collapse
Affiliation(s)
- Keigo Machida
- Department of Molecular Microbiology and Immunology, Research Center for ALPD and Cirrhosis, University of Southern California School of Medicine, 503C-HMR, Los Angeles, CA, 90033, USA,
| |
Collapse
|
|
24
|
Hepatitis C virus and hepatocellular carcinoma. BIOLOGY 2013; 2:304-16. [PMID: 24832662 PMCID: PMC4009856 DOI: 10.3390/biology2010304] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 01/18/2013] [Accepted: 01/23/2013] [Indexed: 12/28/2022]
Abstract
Hepatitis C virus (HCV), a hepatotropic virus, is a single stranded-positive RNA virus of ~9,600 nt. length belonging to the Flaviviridae family. HCV infection causes acute hepatitis, chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC). It has been reported that HCV-coding proteins interact with host-cell factors that are involved in cell cycle regulation, transcriptional regulation, cell proliferation and apoptosis. Severe inflammation and advanced liver fibrosis in the liver background are also associated with the incidence of HCV-related HCC. In this review, we discuss the mechanism of hepatocarcinogenesis in HCV-related liver diseases.
Collapse
|
|
25
|
Goodman ZD, Terracciano LM, Wee A. Tumours and tumour-like lesions of the liver. MACSWEEN'S PATHOLOGY OF THE LIVER 2012:761-851. [DOI: 10.1016/b978-0-7020-3398-8.00014-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2025]
|
|
26
|
Tamura R, Kanda T, Imazeki F, Wu S, Nakamoto S, Tanaka T, Arai M, Fujiwara K, Saito K, Roger T, Wakita T, Shirasawa H, Yokosuka O. Hepatitis C Virus nonstructural 5A protein inhibits lipopolysaccharide-mediated apoptosis of hepatocytes by decreasing expression of Toll-like receptor 4. J Infect Dis 2011; 204:793-801. [PMID: 21844306 DOI: 10.1093/infdis/jir381] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) has been shown to modulate multiple cellular processes, including apoptosis. The aim of this study was to assess the effects of HCV NS5A on apoptosis induced by Toll-like receptor (TLR) 4 ligand, lipopolysaccharide (LPS). METHODS Apoptotic responses to TLR4 ligands and the expression of molecules involved in TLR signaling pathways in human hepatocytes were examined with or without expression of HCV NS5A. RESULTS HCV NS5A protected HepG2 hepatocytes against LPS-induced apoptosis, an effect linked to reduced TLR4 expression. A similar downregulation of TLR4 expression was observed in Huh-7-expressing genotype 1b and 2a. In agreement with these findings, NS5A inhibited the expression of numerous genes encoding for molecules involved in TLR4 signaling, such as CD14, MD-2, myeloid differentiation primary response gene 88, interferon regulatory factor 3, and nuclear factor-κB2. Consistent with a conferred prosurvival advantage, NS5A diminished the poly(adenosine diphosphate-ribose) polymerase cleavage and the activation of caspases 3, 7, 8, and 9 and increased the expression of anti-apoptotic molecules Bcl-2 and c-FLIP. CONCLUSIONS HCV NS5A downregulates TLR4 signaling and LPS-induced apoptotic pathways in human hepatocytes, suggesting that disruption of TLR4-mediated apoptosis may play a role in the pathogenesis of HCV infection.
Collapse
Affiliation(s)
- Ryo Tamura
- Department of Medicine and Clinical Oncology, Chiba University, Graduate School of Medicine, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
|
27
|
Zemel R, Issachar A, Tur-Kaspa R. The role of oncogenic viruses in the pathogenesis of hepatocellular carcinoma. Clin Liver Dis 2011; 15:261-79, vii-x. [PMID: 21689612 DOI: 10.1016/j.cld.2011.03.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
HBV and HCV have major roles in hepatocarcinogenesis. More than 500 million people are infected with hepatitis viruses and, therefore, HCC is highly prevalent, especially in those countries endemic for HBV and HCV. Viral and host factors contribute to the development of HCC. The main viral factors include the circulating load of HBV DNA or HCV RNA and specific genotypes. Various mechanisms are involved in the host-viral interactions that lead to HCC development, among which are genetic instability, self-sufficiency in growth signals, insensitivity to antigrowth signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, and tissue invasiveness. Prevention of HBV by vaccination, as well as antiviral therapy against HBV and for HCV seem able to inhibit the development of HCC.
Collapse
Affiliation(s)
- Romy Zemel
- Department of Medicine D and the Liver Institute, Rabin Medical Center, Beilinson Hospital, Molecular Hepatology Research Laboratory, Felsenstein Medical Research Center, Sackler School of Medicine, Tel Aviv University, 39 Jabotinsky Street, Petah-Tikva 49100, Israel
| | | | | |
Collapse
|
|
28
|
Tsai WL, Chung RT. Viral hepatocarcinogenesis. Oncogene 2010; 29:2309-24. [PMID: 20228847 PMCID: PMC3148694 DOI: 10.1038/onc.2010.36] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 12/29/2009] [Accepted: 01/06/2010] [Indexed: 12/13/2022]
Abstract
Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer death worldwide. Despite recent advances in the diagnosis and treatment of HCC, its prognosis remains dismal. Infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) are the major risk factors for HCC. Although both are hepatotropic viral infections, there are important differences between the oncogenic mechanisms of these two viruses. In addition to the oncogenic potential of its viral proteins, HBV, as a DNA virus, can integrate into host DNA and directly transform hepatocytes. In contrast, HCV, an RNA virus, is unable to integrate into the host genome, and viral protein expression has a more critical function in hepatocarcinogenesis. Both HBV and HCV proteins have been implicated in disrupting cellular signal transduction pathways that lead to unchecked cell growth. Most HCC develops in the cirrhotic liver, but the linkage between cirrhosis and HCC is likely multifactorial. In this review, we summarize current knowledge regarding the pathogenetic mechanisms of viral HCC.
Collapse
Affiliation(s)
- W-L Tsai
- Gastrointestinal Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Division of Gastroenterology, Department of Internal Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - RT Chung
- Gastrointestinal Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
|
29
|
Inhibition of intrahepatic gamma interferon production by hepatitis C virus nonstructural protein 5A in transgenic mice. J Virol 2009; 83:8463-9. [PMID: 19553305 DOI: 10.1128/jvi.00751-09] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) utilizes strategies to suppress or evade the host immune response for establishment of persistent infection. We have shown previously that HCV nonstructural protein 5A (NS5A) impairs tumor necrosis factor alpha (TNF-alpha)-mediated apoptosis. In this study, we have examined the immunomodulatory role of HCV NS5A protein in transgenic mouse (NS5A-Tg) liver when mice were challenged with an unrelated hepatotropic adenovirus as a nonspecific stimulus. Hepatotropic adenovirus was introduced intravenously into NS5A-Tg mice and control mice, and virus clearance from liver was compared over a time course of 3 weeks. The differential mRNA expression levels of 84 cytokine-related genes, signal pathway molecules, transcription factors, and cell surface molecules were determined using real-time reverse transcription-PCR array. NS5A-Tg mice failed to clear adenovirus from liver up to 3 weeks postinfection while control mice cleared virus within 1 to 2 weeks. Subsequent study revealed that gamma interferon (IFN-gamma) expression is inhibited at both the mRNA and protein levels in NS5A-Tg mice, and an inverse expression of transcription factors Gata-3 and Tbx21 is observed. However, TNF-alpha mRNA and protein expression were elevated in both NS5A-Tg and control mice. Together, our results suggested that HCV NS5A acts as an immunomodulator by inhibiting IFN-gamma production and may play an important role toward establishment of chronic HCV infection.
Collapse
|
|
30
|
Rahman MM, Lucas AR, McFadden G. Viral TNF inhibitors as potential therapeutics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 666:64-77. [PMID: 20054975 DOI: 10.1007/978-1-4419-1601-3_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The immune system functions by maintaining a delicate balance between the activities of pro-inflammatory and anti-inflammatory pathways. Unbalanced activation of these pathways often leads to the development of serious inflammatory diseases. TNF (Tumor Necrosis Factor) is a key pro-inflammatory cytokine, which can cause several inflammatory diseases when inappropriately up-regulated. Inhibition of TNF activities by using modulatory recombinant proteins has become a successful therapeutic approach to control TNF activity levels but these anti-TNF reagents also have risks and certain limitations. Biological molecules with a different mode of action in regulating TNF biology might provide a clinically useful alternative to the current therapeutics or in some cases might be efficacious in combination with existinganti-TNF therapies. TNF is also a powerful host defense cytokine commonly induced in the host response against various invading pathogens. Many viral pathogens can block TNF function by encoding modulators of TNF, its receptors or downstream signaling pathways. Here, we review the known virus-encoded TNF inhibitors and evaluate their potential as alternative future anti-TNF therapies.
Collapse
Affiliation(s)
- Masmudur M Rahman
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | | | | |
Collapse
|
|
31
|
Kern MA, Breuhahn K, Schuchmann M, Schirmacher P. [Molecular pathogenesis of hepatocellular carcinoma: new therapeutic approaches and predictive pathology]. DER PATHOLOGE 2008; 28:261-8. [PMID: 17605064 DOI: 10.1007/s00292-007-0890-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hepatocellular carcinoma is one of the most prevalent malignancies worldwide and its incidence is increasing. Multimodal strategies directed towards this carcinoma include primary (e.g. immunisation) and secondary (e.g. antiviral therapy) prevention, surgical approaches, novel specific systemic therapies (targeted therapy), and the treatment of comorbidity (cirrhosis). New molecular approaches are currently under development. These tackle several specific targets, with pathology being challenged in many aspects: experimental evaluation, the development of valid tumor-relevant diagnostic tests as well as morphological evaluation in the context of clinical studies, and finally in routine diagnosis.
Collapse
Affiliation(s)
- M A Kern
- Pathologisches Institut, Universität Heidelberg, Im Neuenheimer Feld 220/221, 69120, Heidelberg, Deutschland.
| | | | | | | |
Collapse
|
|
32
|
Abstract
In recent years, the effects of hepatitis C virus (HCV) proteins on hepatocarcinogenesis have undergone intense investigations. The potentially oncogenic proteins include at least three HCV proteins: core (C) protein, NS3, and NS5A. Several authors indicated relationships between subcellular localization, concentration, a specific molecular form of the proteins (full length, truncated, phosphorylated), the presence of specific domains (the nuclear localization signal homologous to e.g. Bcl-2) and their effects on the mechanisms linked to oncogenesis. The involvement of all the proteins has been described as being in control of the cell cycle, through interactions with key proteins of the process (p53, p21, cyclins, proliferating cell nuclear antigen), transcription factors, proto-oncogenes, growth factors/cytokines and their receptors, and proteins linked to the apoptotic process. Untilnow, the involvement of the core protein of HCV in liver carcinogenesis is the most recognized. One of the most common proteins affected by HCV proteins is the p53 tumor-suppressor protein. The p21/WAF1 gene is a major target of p53, and the effect of HCV proteins on the gene is frequently considered in parallel. The results of studies on the effects of HCV proteins on the apoptotic process are controversial. This work summarizes the information collected thus far in the field of HCV molecular virology and principal intracellular signaling pathways in which HCV oncogenic proteins are involved.
Collapse
Affiliation(s)
- Aldona Kasprzak
- Department of Histology and Embryology, Medical University, Poznań, Poland
| | | |
Collapse
|
|
33
|
Kohashi T, Maekawa S, Sakamoto N, Kurosaki M, Watanabe H, Tanabe Y, Chen CH, Kanazawa N, Nakagawa M, Kakinuma S, Yamashiro T, Itsui Y, Koyama T, Enomoto N, Watanabe M. Site-specific mutation of the interferon sensitivity-determining region (ISDR) modulates hepatitis C virus replication. J Viral Hepat 2006; 13:582-90. [PMID: 16907844 DOI: 10.1111/j.1365-2893.2006.00739.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The number of amino acid substitutions in the interferon sensitivity-determining region (ISDR) in the nonstructural 5A (NS5A) gene of hepatitis C virus (HCV) is closely associated with the interferon (IFN) response and viral load. Several HCV replicon-based studies have reported that ISDR sequences had an influence on viral replication in vitro. However, it is unclear as to how different ISDR sequences affect HCV replication. Various clinically observed ISDR sequences were introduced into HCV replicons and their contribution to viral replication was investigated using a colony formation assay and/or a transient replication assay. A mapping study of the ISDR was performed to identify the amino acid positions that critically affect replication. While no colonies were formed in the colony formation assay using HCV replicons with few mutations (0, 1 and 3) in the ISDR, numerous colonies (>200) appeared when using constructs with six mutations. Introduction of various distinct ISDR sequences with multiple mutations resulted in replication enhancement in transient assays. A mapping study identified several specific sites in the ISDR that critically affected replication, including codon 2209 which, in patients, was closely associated with a strong response to IFN. ISDR sequences associated with a clinical IFN response and viral load modulated the replication of HCV replicons, suggesting the importance of the ISDR sequence in HCV infection.
Collapse
Affiliation(s)
- T Kohashi
- Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Yushima, Bunkyo, Tokyo, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
|
34
|
Kalamvoki M, Georgopoulou U, Mavromara P. The NS5A protein of the hepatitis C virus genotype 1a is cleaved by caspases to produce C-terminal-truncated forms of the protein that reside mainly in the cytosol. J Biol Chem 2006; 281:13449-13462. [PMID: 16517592 DOI: 10.1074/jbc.m601124200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The nonstructural 5A (NS5A) protein of the hepatitis C virus (HCV) is a multifunctional protein that is implicated in viral replication and pathogenesis. We report here that NS5A of HCV-1a is cleaved at multiple sites by caspase proteases in transfected cells. Two cleavage sites at positions Asp154 and 248DXXD251 were mapped. Cleavage at Asp154 has been previously recognized as one of the caspase cleavage sites for the NS5A protein of HCV genotype 1b (1, 2) and results in the production of a 17-kDa fragment. The sequence 248DXXD251 is a novel caspase recognition motif for NS5A and is responsible for the production of a 31-kDa fragment. Furthermore, we show that Arg217 is implicated in the production of the previously described 24-kDa product, whose accumulation is affected by both calpain and caspase inhibitors. We also showed that caspase-mediated cleavage occurs in the absence of exogenous proapoptotic stimuli and is not related to the accumulation of the protein in the endoplasmic reticulum. Interestingly, our data indicate that NS5A is targeted by at least two different caspases and suggest that caspase 6 is implicated in the production of the 17-kDa fragment. Most importantly, we report that, all the detectable NS5A fragments following caspase-mediated cleavage are C-terminal-truncated forms of NS5A and are mainly localized in the cytosol. Thus, in sharp contrast to the current view we found no evidence supporting a role for caspase-mediated cleavage in the transport of the NS5A protein to the nucleus, which could lead to transcriptional activation.
Collapse
Affiliation(s)
- Maria Kalamvoki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 115 21 Athens, Greece
| | - Urania Georgopoulou
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 115 21 Athens, Greece
| | - Penelope Mavromara
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 115 21 Athens, Greece.
| |
Collapse
|
|
35
|
Choi SH, Hwang SB. Modulation of the transforming growth factor-beta signal transduction pathway by hepatitis C virus nonstructural 5A protein. J Biol Chem 2006; 281:7468-78. [PMID: 16407286 DOI: 10.1074/jbc.m512438200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Transforming growth factor-beta (TGF-beta) is implicated in the pathogenesis of liver disease. TGF-beta is involved both in liver regeneration and in the fibrotic and cirrhotic transformation with hepatitis viral infection. Hepatitis C virus (HCV) infection often leads to cirrhosis and hepatocellular carcinoma. HCV nonstructural 5A (NS5A) protein is a multifunctional protein that modulates cytokine-mediated signal transduction pathways. To elucidate the molecular mechanism of HCV pathogenesis, we examined the effect of NS5A protein on TGF-beta-stimulated signaling cascades. We show that NS5A protein inhibited the TGF-beta-mediated signaling pathway in hepatoma cell lines as determined by reporter gene assay. To further investigate the role of NS5A, we examined the protein/protein interaction between NS5A and TGF-beta signal transducers. Both in vitro and in vivo binding data showed that NS5A protein directly interacted with TGF-beta receptor I (TbetaR-I) in hepatoma cell lines. This interaction was mapped to amino acids 148-238 of NS5A. We also found that NS5A protein co-localized with TbetaR-I in the cytoplasm of Huh7 cells and inhibited TGF-beta-mediated nuclear translocation of Smad2. Furthermore, we demonstrate that NS5A protein abrogated the phosphorylation of Smad2 and the heterodimerization of Smad3 and Smad4. To further explore the relevance to viral infection, we examined the effect of the HCV subgenomic replicon on the TGF-beta signaling pathway. We show that the HCV subgenomic replicon also inhibited TGF-beta-induced signaling cascades. These results indicate that HCV NS5A modulates TGF-beta signaling through interaction with TbetaR-I and that NS5A may be an important risk factor in HCV-associated liver pathogenesis.
Collapse
Affiliation(s)
- Soo-Ho Choi
- Ilsong Institute of Life Science, Hallym University, 1 Ockcheon-dong, Chuncheon 200-702, Korea
| | | |
Collapse
|
|
36
|
Lapinski TW, Panasiuk A, Jaroszewicz J, Kowalczuk O, Flisiak R, Rogalska M. Specific ssDNA concentration in liver tissue as an index of apoptosis in hepatitis C virus-infected patients. World J Gastroenterol 2005; 11:6130-3. [PMID: 16273639 PMCID: PMC4436629 DOI: 10.3748/wjg.v11.i39.6130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To evaluate the activity of apoptosis in liver tissue and explore its possible association with hepatic necroinflam-mation and fibrosis as well as serum hepatitis C virus (HCV) load.
METHODS: The studied population included 50 chronic hepatitis C patients (20 women and 30 men, aged 18-66 years). HCV-RNA quantification was performed by two-step real-time quantitative RT-PCR method using the TaqMan technology (reagents of Applera Corporation firm, USA). The morphology of liver tissue was assessed descriptively and scored (necroinflammatory activity and fibrosis). The early apoptosis activity in liver tissue was examined by ssDNA apoptosis ELISA kit, (Chemicon, Germany).
RESULTS: The correlation between apoptosis and fibrosis in liver tissue was observed. High intensification of apoptosis was proportional to the increase of fibrosis (ssDNA: 16.65×10-5 mg/g; 12.71×10-5 mg/g), however, this difference was not statistically significant (P>0.05). Activity of apoptosis in the liver tissue, expressed by ssDNA concentration did not depend on hepatic necroinflammatory changes, HCV-RNA viral load, ALT, and AST activity as well as prothrombin time and INR index.
CONCLUSION: Fibrosis in the tissue is closely associated with early apoptosis in HCV-infected patients.
Collapse
Affiliation(s)
- Tadeusz-Wojciech Lapinski
- Department of Infectious Diseases, Medical University of Bialystok, Bialystok 15-540, Zurawia str, 14, Poland.
| | | | | | | | | | | |
Collapse
|
|
37
|
Siavoshian S, Abraham JD, Thumann C, Kieny MP, Schuster C. Hepatitis C virus core, NS3, NS5A, NS5B proteins induce apoptosis in mature dendritic cells. J Med Virol 2005; 75:402-11. [PMID: 15648076 DOI: 10.1002/jmv.20283] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Although reasons for hepatitis C virus (HCV) persistence are still unknown, specific cellular immune responses appear to influence the pathogenesis and outcome of the infection. Apoptosis of cells infected by viruses may appear suicidal to the viruses that induce programmed cell death of its host. However, apoptosis has been suggested to be a response to virus infection as a mean of facilitating virus dissemination. Annexin V-propidium iodide staining and DNA fragmentation, were used to show that expression of the core, NS3, NS5A, or NS5B protein induces apoptosis in mature dendritic cells. In addition, immunoblotting was used to demonstrate that expression level of p21waf1/cip1 protein decreased in cells expressing one of these HCV proteins. No expression of p53 could be detected and expression of Akt was independent of HCV proteins expression. These results suggest that the effect of these HCV proteins on HCV associated pathogenesis may be linked (at least partially) to its ability to modulate apoptosis pathways in mature dendritic cells.
Collapse
|
|
38
|
Street A, Macdonald A, McCormick C, Harris M. Hepatitis C virus NS5A-mediated activation of phosphoinositide 3-kinase results in stabilization of cellular beta-catenin and stimulation of beta-catenin-responsive transcription. J Virol 2005; 79:5006-16. [PMID: 15795286 PMCID: PMC1069556 DOI: 10.1128/jvi.79.8.5006-5016.2005] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Accepted: 01/03/2005] [Indexed: 01/04/2023] Open
Abstract
The hepatitis C virus (HCV) nonstructural NS5A protein has been shown to bind to and activate phosphoinositide 3-kinase (PI3K), resulting in activation of the downstream effector serine/threonine kinase Akt/protein kinase B. Here we present data pertaining to the effects of NS5A-mediated Akt activation on its downstream targets. Using a recombinant baculovirus to deliver the complete HCV polyprotein to human hepatoma cells in a tetracycline-regulable fashion, we confirm that expression of the complete HCV polyprotein also activates PI3K and Akt. We further show that this results in the inhibition of the Akt substrate Forkhead transcription factor and the stimulation of phosphorylation of a second key Akt substrate, glycogen synthase kinase-3beta (GSK-3beta). Phosphorylation of GSK-3beta results in its inactivation; consistent with this, we show that expression of the HCV polyprotein results in the accumulation of beta-catenin. Finally, we show that levels of beta-catenin-dependent transcription are also elevated in the presence of the HCV polyprotein. Given the prevalence of beta-catenin mutations in many human tumors, especially colon and hepatocellular carcinomas, these data implicate NS5A-mediated PI3K activation as a contributory factor in the increasingly common association between HCV infection and the development of hepatocellular carcinoma.
Collapse
Affiliation(s)
- Andrew Street
- School of Biochemistry and Microbiology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | | | | |
Collapse
|
|
39
|
Yoshioka K, Ito H, Watanabe K, Yano M, Ishigami M, Mizutani T, Sasaki Y, Goto H. Interferon sensitivity-determining region of nonstructural region 5A of hepatitis C virus genotype 1b correlates with serum alanine aminotransferase levels in chronic infection. J Viral Hepat 2005; 12:139-45. [PMID: 15720528 DOI: 10.1111/j.1365-2893.2005.00561.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The mutations in the interferon (IFN) sensitivity-determining region (ISDR) of nonstructural region 5A (NS5A) of hepatitis C virus (HCV) have been correlated with response to IFN therapy. NS5A appears to disrupt a host antiviral pathway that plays a role in suppressing virus replication and protects hepatocytes from apoptosis. We assessed whether ISDR correlates with viral load and serum alanine aminotransferase (ALT) levels. Serum viral load and ALT levels were prospectively measured bimonthly by HCV core protein assay and monthly, respectively, for 22 months in 87 patients chronically infected with HCV genotype 1b. ISDR of HCV was directly sequenced from the products of reverse transcription and polymerase chain reaction of HCV RNA. Five patients had four or more substitutions (mutant type), 33 had 1-3 (intermediate type), and 49 had no substitutions (wild type) in ISDR. The numbers of substitutions in ISDR were inversely correlated with mean viral load over a 22-month period (r = 0.292, P = 0.0060) and directly with mean serum ALT levels (r = 0.360, P = 0.0006). The numbers of substitutions in ISDR was significantly larger in the patients with changes of viral load more than fivefold during the 22 months (1.4 +/- 2.4) than in those without changes (0.6 +/- 0.8) (P = 0.0188). The present study demonstrates that the patients with more substitutions in ISDR had significantly higher serum ALT levels and smaller viral load. These results suggest that NS5A with more substitutions in ISDR may lose the ability to block host antiviral pathways and to protect hepatocytes from apoptosis.
Collapse
Affiliation(s)
- K Yoshioka
- Department of Internal Medicine, Division of Gastroenterology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
|
40
|
Lapinski TW, Kowalczuk O, Prokopowicz D, Chyczewski L. Serum concentration of sFas and sFasL in healthy HBsAg carriers, chronic viral hepatitis B and C patients. World J Gastroenterol 2004; 10:3650-3. [PMID: 15534924 PMCID: PMC4612010 DOI: 10.3748/wjg.v10.i24.3650] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To estimate the amount of apoptosis among healthy HBsAg carriers, patients with chronic HBV infection treated with lamivudine and patients with chronic HCV infection treated with interferon alpha and ribavirin. Activity of apoptosis was evaluated by serum sFas/sFasL concentration measurement. Moreover dependence between apoptosis and HBV-DNA or HCV-RNA levels was studied.
METHODS: Eighty-six persons were included into study: 34 healthy HBsAg carriers, 33 patients with chronic HBV infection and 19 patients with chronic HCV infection. Serum levels of sFas/sFasL were measured by ELISA assay. HBV-DNA and HCV-RNA were measured by RT-PCR assay. Levels of sFas/sFasL were determined before and 2 and 12 wk after therapy in patients with chronic hepatitis B and C infection. HBV-DNA or HCV-RNA was detected before treatment and 6 mo after treatment.
RESULTS: Twenty-four (71%) healthy HBsAg carriers showed HBV-DNA over 105/mL, which was comparable to the patients with chronic hepatitis B. Independently from HBV-DNA levels, the concentration of sFas among healthy HBsAg carriers was comparable to healthy persons. Among patients with chronic hepatitis B and C, the concentration of sFas was significantly higher in comparison to healthy HBsAg carriers and healthy persons. In chronic hepatitis B patients the concentration of sFas was decreased during lamivudine treatment. Among chronic hepatitis C patients the concentration of sFas was increased during IFN alpha and ribavirin treatment. sFasL was not detected in control group. Furthermore sFasL occurred more frequently in chronic hepatitis C patients in comparison to chronic hepatitis B patients.
CONCLUSION: There are no correlations between apoptosis and HBV-DNA levels. However ther is an association between apoptosis and activity of inflammation in patients with chronic HBV infection. Apoptosis can be increased in patients with chronic hepatitis C by effective treatment which may be a result of apoptosis stimulation by IFN-α.
Collapse
Affiliation(s)
- Tadeusz-Wojciech Lapinski
- Department of Infectious Diseases, Medical University of Bialystok, 15-540 Bialystok, Zurawia str., 14, Poland.
| | | | | | | |
Collapse
|
|
41
|
Prikhod'ko EA, Prikhod'ko GG, Siegel RM, Thompson P, Major ME, Cohen JI. The NS3 protein of hepatitis C virus induces caspase-8-mediated apoptosis independent of its protease or helicase activities. Virology 2004; 329:53-67. [PMID: 15476874 DOI: 10.1016/j.virol.2004.08.012] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2004] [Revised: 06/07/2004] [Accepted: 08/11/2004] [Indexed: 12/21/2022]
Abstract
Apoptosis has been implicated in the pathogenesis of hepatitis C virus (HCV)-related disease. Here, we show that expression of HCV NS3, or the NS2/NS3 precursor protein, in mammalian cells results in induction of apoptosis and activation of caspases. HCV NS3-induced apoptosis was blocked by a caspase-8, but not a caspase-9-specific inhibitor. HCV NS3 coimmunoprecipitated with caspase-8, but not with other caspases or with FADD. Coexpression of HCV NS3 and caspase-8 resulted in aggregation of the caspase in punctate structures that colocalized with HCV NS3. Cell lines stably expressing low levels HCV NS3 showed increased sensitivity to Fas-induced cell death. Point mutations of NS3 showed that the pro-apoptotic function of the protein is distinct from its protease and helicase activities. These findings suggest that HCV NS3 promotes caspase-8 induced apoptosis at a pathway site distal to FADD, and that flavivirus NS3 may represent a new class of pro-apoptotic proteins.
Collapse
Affiliation(s)
- Elena A Prikhod'ko
- Medical Virology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
| | | | | | | | | | | |
Collapse
|
|
42
|
Kalamvoki M, Mavromara P. Calcium-dependent calpain proteases are implicated in processing of the hepatitis C virus NS5A protein. J Virol 2004; 78:11865-78. [PMID: 15479828 PMCID: PMC523276 DOI: 10.1128/jvi.78.21.11865-11878.2004] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The nonstructural 5A (NS5A) protein of the hepatitis C virus (HCV) is a multifunctional phosphoprotein that is implicated in viral replication and HCV-mediated pathogenesis. We report here that the NS5A protein from the HCV genotype 1a is processed into shorter distinct forms when expressed in mammalian cells (Vero, HepG2, HuH-7, and WRL68) infected with an NS5A-expressing HSV-1-based amplicon vector or when transiently transfected with NS5A-expressing plasmids in the absence of exogenous apoptotic stimuli. Inhibitor studies combined with cell-free cleavage assays suggest that calcium-dependent calpain proteases, in addition to caspase-like proteases, are involved in NS5A processing. Interestingly, His-tagging experiments indicated that all the detectable NS5A-cleaved products are N-terminal forms of the protein. Additionally, immunofluorescence studies showed that, despite proteolytic cleavage, the NS5A protein exhibits a cytoplasm-perinuclear localization similar to that of the full-length protein. Thus, our results are consistent with recent data that demonstrated that NS5A is capable of perturbing intracellular calcium homeostasis and suggest that NS5A is both an inducer and a substrate of the calcium-dependent calpain protease(s). This may imply that cleavage of NS5A by calpain(s) could play a role in the modulation of NS5A function.
Collapse
Affiliation(s)
- M Kalamvoki
- Hellenic Pasteur Institute, Laboratory of Molecular Virology, 127 Vas. Sofias Ave., Athens, Greece 115 21
| | | |
Collapse
|
|
43
|
Abstract
The non-structural 5A (NS5A) protein of hepatitis C virus (HCV) has been the subject of intensive research over the last decade. It is generally accepted that NS5A is a pleiotropic protein with key roles in both viral RNA replication and modulation of the physiology of the host cell. Our understanding of the role of NS5A in the virus life cycle has been hampered by the lack of a robust in vitro system for the study of HCV replication, although the recent development of the subgenomic replicon has at least allowed us to begin to dissect the involvement of NS5A in the process of viral RNA replication. Early studies into the effects of NS5A on cell physiology relied on expression of NS5A either alone or in the context of other non-structural proteins; the advent of the replicon system has allowed the extrapolation of these studies to a more physiologically relevant cellular context. Despite recent progress, this field is controversial, and there is much work to be accomplished before we fully understand the many functions of this protein. In this article, the current state of our knowledge of NS5A, discussing in detail its direct involvement in virus replication, together with its role in modulating the cellular environment to favour virus replication and persistence, are reviewed. The effects of NS5A on interferon signalling, and the regulation of cell growth and apoptosis are highlighted, demonstrating that this protein is indeed of critical importance for HCV and is worthy of further investigation.
Collapse
Affiliation(s)
- Andrew Macdonald
- School of Biochemistry & Microbiology and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Mark Harris
- School of Biochemistry & Microbiology and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| |
Collapse
|
|
44
|
Maekawa S, Enomoto N, Sakamoto N, Kurosaki M, Ueda E, Kohashi T, Watanabe H, Chen CH, Yamashiro T, Tanabe Y, Kanazawa N, Nakagawa M, Sato C, Watanabe M. Introduction of NS5A mutations enables subgenomic HCV replicon derived from chimpanzee-infectious HC-J4 isolate to replicate efficiently in Huh-7 cells. J Viral Hepat 2004; 11:394-403. [PMID: 15357644 DOI: 10.1111/j.1365-2893.2004.00525.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hepatitis C virus (HCV) subgenomic replicon has been reported to replicate efficiently and continuously in human hepatoma Huh-7 cells. To extend the previous results to other isolated HCV clones, we constructed another HCV replicon from HC-J4, one of chimpanzee-infectious HCV clones. An HCV replicon derived from HC-J4 (RpJ4) consists of HCV-5' untranslated region, neomycin phosphotransferase gene, the encephalomyocarditis virus internal ribosomal entry site, HCV nonstructural region, NS3 to NS5B, and HCV-3' untranslated region. The adaptive mutations known to be required for HCV-Con1 replicon were introduced in RpJ4 replicon, aa.(amino acids number according to HC-J4) 2197 serine to proline, deletion of serine at aa.2201, and aa.2204 serine to isoleucine (RpJ4-S2197P, RpJ4-S22001del, and RpJ4-S2204I). RpJ4/ISDR mutant and RpJ4-S2201del/ISDR mutant were also constructed by introducing six amino acid mutations into the interferon sensitivity determining region (ISDR). After transfection into Huh-7 cells and G418 selection, RpJ4 and RpJ4/ISDR mutants did not produce any colony. In contrast, G418-resistant cells were transduced efficiently by RpJ4-S2197P, RpJ4-S2204I, RpJ4-S2201del and RpJ4-S2201del/ISDR mutant, with the RpJ4-S2201del/ISDR mutant being most efficient. Hence the HCV replicon derived from HC-J4 can replicate efficiently following the introduction of adaptive mutations into the upstream region of ISDR. Moreover, additional introduction of mutations into ISDR further enhanced its replication. These findings demonstrate that the genetic structure of the NS5A domain is critical in HCV replications.
Collapse
Affiliation(s)
- S Maekawa
- Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo 113-8519, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
|
45
|
Basu A, Steele R, Ray R, Ray RB. Functional properties of a 16 kDa protein translated from an alternative open reading frame of the core-encoding genomic region of hepatitis C virus. J Gen Virol 2004; 85:2299-2306. [PMID: 15269371 DOI: 10.1099/vir.0.80028-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hepatitis C virus (HCV) often causes persistent infection in humans. This could be due in part to the effect of viral proteins on cellular gene expression. Earlier observations suggest that the HCV core protein expressed from genotype 1a modulates important cellular genes at the transcriptional level, affects programmed cell death (apoptosis) and promotes cell growth. Recently, different groups of investigators have reported the translation of an approximately 16 kDa protein (named F/ARFP/core+1 ORF) from an alternate open reading frame of the HCV core-encoding genomic region. The functional significance of this F protein is presently unknown. Thus, whether the F and core proteins have both shared and distinct functions was investigated here. The experimental observations suggested that the F protein does not significantly modulate c-myc, hTERT and p53 promoter activities, unlike the HCV core protein. Interestingly, the F protein repressed p21 expression. Further studies indicated that the F protein does not inhibit tumour necrosis factor alpha-mediated apoptosis of HepG2 cells or promote rat embryo fibroblast growth. Taken together, these results suggest that the F protein does not share major properties identified previously for the HCV core protein, other than regulating p21 expression.
Collapse
Affiliation(s)
- Arnab Basu
- Department of Internal Medicine, Saint Louis University, St Louis, MO 63110, USA
| | - Robert Steele
- Department of Pathology, Saint Louis University, St Louis, MO 63110, USA
| | - Ranjit Ray
- Department of Molecular Microbiology and Immunology, Saint Louis University, St Louis, MO 63110, USA
- Department of Internal Medicine, Saint Louis University, St Louis, MO 63110, USA
| | - Ratna B Ray
- Department of Pathology, Saint Louis University, St Louis, MO 63110, USA
- Department of Internal Medicine, Saint Louis University, St Louis, MO 63110, USA
| |
Collapse
|
|
46
|
Gong GZ, Jiang YF, He Y, Lai LY, Zhu YH, Su XS. HCV NS5A abrogates p53 protein function by interfering with p53-DNA binding. World J Gastroenterol 2004; 10:2223-7. [PMID: 15259070 PMCID: PMC4724976 DOI: 10.3748/wjg.v10.i15.2223] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Revised: 12/23/2003] [Accepted: 01/08/2004] [Indexed: 12/15/2022] Open
Abstract
AIM To evaluate the inhibition effect of HCV NS5A on p53 transactivation on p21 promoter and explore its possible mechanism for influencing p53 function. METHODS p53 function of transactivation on p21 promoter was studied with a luciferase reporter system in which the luciferase gene is driven by p21 promoter, and the p53-DNA binding ability was observed with the use of electrophoretic mobility-shift assay (EMSA). Lipofectin mediated p53 or HCV NS5A expression vectors were used to transfect hepatoma cell lines to observe whether HCV NS5A could abrogate the binding ability of p53 to its specific DNA sequence and p53 transactivation on p21 promoter. Western blot experiment was used for detection of HCV NS5A and p53 proteins expression. RESULTS Relative luciferase activity driven by p21 promoter increased significantly in the presence of endogenous p53 protein. Compared to the control group, exogenous p53 protein also stimulated p21 promoter driven luciferase gene expression in a dose-dependent way. HCV NS5A protein gradually inhibited both endogenous and exogenous p53 transactivation on p21 promoter with increase of the dose of HCV NS5A expression plasmid. By the experiment of EMSA, we could find p53 binding to its specific DNA sequence and, when co-transfected with increased dose of HCV NS5A expression vector, the p53 binding affinity to its DNA gradually decreased and finally disappeared. Between the Huh 7 cells transfected with p53 expression vector alone or co-transfected with HCV NS5A expression vector, there was no difference in the p53 protein expression. CONCLUSION HCV NS5A inhibits p53 transactivation on p21 promoter through abrogating p53 binding affinity to its specific DNA sequence. It does not affect p53 protein expression.
Collapse
Affiliation(s)
- Guo-Zhong Gong
- Center for Liver Diseases, Second Xiangya Hospital, Central South University, 86 Renmin Zhong Road, Changsha 410011, Hunan Province, China.
| | | | | | | | | | | |
Collapse
|
|
47
|
Sarcar B, Ghosh AK, Steele R, Ray R, Ray RB. Hepatitis C virus NS5A mediated STAT3 activation requires co-operation of Jak1 kinase. Virology 2004; 322:51-60. [PMID: 15063116 DOI: 10.1016/j.virol.2004.01.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2003] [Revised: 12/09/2003] [Accepted: 01/05/2004] [Indexed: 12/21/2022]
Abstract
Hepatitis C virus (HCV) is a major etiologic agent for chronic hepatitis worldwide and often leads to cirrhosis and hepatocellular carcinoma. However, the mechanism for development of chronic hepatitis or hepatocarcinogenesis by HCV remains unclear. Signal transducers and activators of transcription (STATs) family proteins function as the downstream effectors of cytokine signaling and play a critical role in cell growth regulation. In many cancers including liver, STAT3 is often constitutively activated, although the mechanism of persistent activation of STAT3 is unknown. The nonstructural protein 5A (NS5A) encoded from the HCV genome has shown cell growth regulatory properties. In this study, we have observed that HCV NS5A activates STAT3 phosphorylation, which in turn translocates into the nucleus. In vivo activation of STAT3 was also observed in the liver of transgenic mice expressing HCV NS5A. Introduction of NS5A in hepatoma cells modulated STAT3 downstream molecules Bcl-xL and p21 expression. To determine if STAT3 activation by NS5A could induce STAT3 mediated gene expression, a luciferase reporter construct based on a synthetic promoter was used to transfect hepatoma cells. Activation of endogenous cellular STAT3 by HCV NS5A induced luciferase gene expression through STAT3 specific binding elements. Our subsequent studies suggested that NS5A forms a complex with Jak1 and recruits STAT3 for activation. Taken together, our results suggested that NS5A activates STAT3 through co-operation of Jak1 kinase and activated STAT3 may contribute to HCV-mediated pathogenesis.
Collapse
Affiliation(s)
- Bhaswati Sarcar
- Department of Pathology, Saint Louis University, St. Louis, MO 63104, USA
| | | | | | | | | |
Collapse
|
|
48
|
N/A. N/A. Shijie Huaren Xiaohua Zazhi 2004; 12:928-932. [DOI: 10.11569/wcjd.v12.i4.928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
|
|
49
|
Majumder M, Steele R, Ghosh AK, Zhou XY, Thornburg L, Ray R, Phillips NJ, Ray RB. Expression of hepatitis C virus non-structural 5A protein in the liver of transgenic mice. FEBS Lett 2004; 555:528-32. [PMID: 14675768 DOI: 10.1016/s0014-5793(03)01337-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hepatitis C virus (HCV) is a major etiologic agent for chronic hepatitis worldwide often leading to the development of cirrhosis and hepatocellular carcinoma. However, the mechanism for development of chronic hepatitis or hepatocarcinogenesis by HCV remains unclear. HCV NS5A protein possesses many intriguing properties, including sequestration of p53 in the cytoplasm, downregulation of p21 protein, activation of STAT3, and inhibition of tumor necrosis factor-alpha-mediated apoptosis. Thus, we investigated whether this viral protein has oncogenic property in vivo. In the absence of an efficient cell culture system for virus growth and a suitable small animal model for HCV infection, transgenic FVB mice were generated by targeting the HCV NS5A genomic region cloned under the control of a liver-specific apoE promoter or mouse major urinary promoter (MUP). The apoE promoter is constitutively expressed in liver, on the other hand, the MUP is developmentally regulated and expressed in the liver after birth. Reverse transcription polymerase chain reaction and Western blot analysis indicated establishment of HCV NS5A transgene expression in several lines from both groups of mice. Immunohistochemical studies suggested the presence of NS5A in the cytoplasm of hepatocytes. The transgenic animals were phenotypically similar to their normal littermates and did not exhibit a major histological change within the liver up to 24 months of age. Our results suggested HCV NS5A protein is not directly cytopathic or oncogenic in this FVB transgenic mouse model, although this viral protein promotes cell growth in vitro. These animals will be a valuable model of HCV immunopathology as well as for evaluation of siRNA, interferon and other cytokine therapies.
Collapse
Affiliation(s)
- Mainak Majumder
- Department of Pathology, Saint Louis University, 1402 S. Grand Blvd., 4th Floor, St. Louis, MO 63104, USA
| | | | | | | | | | | | | | | |
Collapse
|
|
50
|
Chung YL, Sheu ML, Yen SH. Hepatitis C virus NS5A as a potential viral Bcl-2 homologue interacts with Bax and inhibits apoptosis in hepatocellular carcinoma. Int J Cancer 2003; 107:65-73. [PMID: 12925958 DOI: 10.1002/ijc.11303] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Treatment of hepatocellular carcinoma (HCC) cells with butyrate can induce apoptosis irrespective of hepatitis B virus integration. No information is available, however, regarding the effect of butyrate on HCC in the presence of hepatitis C virus (HCV) because some HCV proteins can regulate cell survival. By gene transfer, we found that HCV core enhances but HCV NS5A antagonizes sodium phenylbutyrate (NaPB)-induced apoptosis in HCC cells, which is independent of p53. We then chose the p53-negative Hep3B HCC cell to investigate the mechanism of anti-apoptosis mediated by NS5A. In the NaPB-treated Hep3B cells without NS5A expression, induction of apoptosis was associated with Bax redistribution from the cytosol to the nucleus interior and subsequently, to a nuclear membrane-bound form. In the NS5A expressing Hep3B cells, NaPB treatment also triggered relocalization of both Bax and NS5A from the cytosol to the nucleus interior but Bax retained inside the nucleus and did not finally move to the nuclear membrane. Using double immunofluorescence and coimmunoprecipitation, we demonstrated that NS5A co-localizes and interacts with Bax in the nucleus. The HCV NS5A protein was further found to contain Bcl-2 homology domains (BH3, BH1 and BH2). Additional studies using deleted NS5A constructs were carried out to determine whether the BH2 domain or nuclear localization signal (NLS) in NS5A is required for interaction with Bax in the nucleus or inhibition of apoptosis. NS5A with deletion of both BH2 domain and NLS localized in the cytoplasm, dissociated with Bax, and lost anti-apoptosis activity during NaPB treatment. In contrast, NS5A with intact BH domains except NLS still bound directly to Bax in the perinuclear region or the nucleus, but showed less association with Bax in the nucleus and lower effect in apoptosis inhibition than full-length NS5A. These results suggest that HCV NS5A as a Bcl-2 homologue interacts with Bax to protect p53-negative HCC cells from NaPB-induced apoptosis.
Collapse
Affiliation(s)
- Yih-Lin Chung
- Department of Radiation Oncology, Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan, Republic of China.
| | | | | |
Collapse
|