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1
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Villanueva RA, Loyola A. The Intrinsically Disordered Region of HBx and Virus-Host Interactions: Uncovering New Therapeutic Approaches for HBV and Cancer. Int J Mol Sci 2025; 26:3552. [PMID: 40332052 PMCID: PMC12026620 DOI: 10.3390/ijms26083552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2025] [Revised: 04/02/2025] [Accepted: 04/07/2025] [Indexed: 05/08/2025] Open
Abstract
Human viral infections remain a significant global health challenge, contributing to a substantial number of cancer cases worldwide. Among them, infections with oncoviruses such as hepatitis B virus (HBV) and hepatitis C virus (HCV) are key drivers of hepatocellular carcinoma (HCC). Despite the availability of an effective HBV vaccine since the 1980s, millions remain chronically infected due to the persistence of covalently closed circular DNA (cccDNA) as a reservoir in hepatocytes. Current antiviral therapies, including nucleos(t)ide analogs and interferon, effectively suppress viral replication but fail to eliminate cccDNA, underscoring the urgent need for innovative therapeutic strategies. Direct-acting antiviral agents (DAAs), which have revolutionized HCV treatment with high cure rates, offer a promising model for HBV therapy. A particularly attractive target is the intrinsically disordered region (IDR) of the HBx protein, which regulates cccDNA transcription, viral replication, and oncogenesis by interacting with key host proteins. DAAs targeting these interactions could inhibit viral persistence, suppress oncogenic signaling, and overcome treatment resistance. This review highlights the potential of HBx-directed DAAs to complement existing therapies, offering renewed hope for a functional HBV cure and reduced cancer risk.
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Affiliation(s)
- Rodrigo A. Villanueva
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago 8580702, Chile
| | - Alejandra Loyola
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago 8580702, Chile
- Facultad de Ciencias, Universidad San Sebastián, Santiago 7510602, Chile
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2
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Choonnasard A, Shofa M, Okabayashi T, Saito A. Conserved Functions of Orthohepadnavirus X Proteins to Inhibit Type-I Interferon Signaling. Int J Mol Sci 2024; 25:3753. [PMID: 38612565 PMCID: PMC11011558 DOI: 10.3390/ijms25073753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 03/19/2024] [Accepted: 03/25/2024] [Indexed: 04/14/2024] Open
Abstract
Orthohepadnavirus causes chronic hepatitis in a broad range of mammals, including primates, cats, woodchucks, and bats. Hepatitis B virus (HBV) X protein inhibits type-I interferon (IFN) signaling, thereby promoting HBV escape from the human innate immune system and establishing persistent infection. However, whether X proteins of Orthohepadnavirus viruses in other species display a similar inhibitory activity remains unknown. Here, we investigated the anti-IFN activity of 17 Orthohepadnavirus X proteins derived from various hosts. We observed conserved activity of Orthohepadnavirus X proteins in inhibiting TIR-domain-containing adaptor protein inducing IFN-β (TRIF)-mediated IFN-β signaling pathway through TRIF degradation. X proteins from domestic cat hepadnavirus (DCH), a novel member of Orthohepadnavirus, inhibited mitochondrial antiviral signaling protein (MAVS)-mediated IFNβ signaling pathway comparable with HBV X. These results indicate that inhibition of IFN signaling is conserved in Orthohepadnavirus X proteins.
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Affiliation(s)
- Amonrat Choonnasard
- Department of Veterinary Science, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan; (A.C.); (M.S.); (T.O.)
- Graduate School of Medicine and Veterinary Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Maya Shofa
- Department of Veterinary Science, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan; (A.C.); (M.S.); (T.O.)
- Graduate School of Medicine and Veterinary Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Tamaki Okabayashi
- Department of Veterinary Science, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan; (A.C.); (M.S.); (T.O.)
- Graduate School of Medicine and Veterinary Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
- Center for Animal Disease Control, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Akatsuki Saito
- Department of Veterinary Science, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan; (A.C.); (M.S.); (T.O.)
- Graduate School of Medicine and Veterinary Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
- Center for Animal Disease Control, University of Miyazaki, Miyazaki 889-2192, Japan
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3
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Liu F, Liao Z, Zhang Z. MYC in liver cancer: mechanisms and targeted therapy opportunities. Oncogene 2023; 42:3303-3318. [PMID: 37833558 DOI: 10.1038/s41388-023-02861-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/28/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023]
Abstract
MYC, a major oncogenic transcription factor, regulates target genes involved in various pathways such as cell proliferation, metabolism and immune evasion, playing a critical role in the tumor initiation and development in multiple types of cancer. In liver cancer, MYC and its signaling pathways undergo significant changes, exerting a profound impact on liver cancer progression, including tumor proliferation, metastasis, dedifferentiation, metabolism, immune microenvironment, and resistance to comprehensive therapies. This makes MYC an appealing target, despite it being previously considered an undruggable protein. In this review, we discuss the role and mechanisms of MYC in liver physiology, chronic liver diseases, hepatocarcinogenesis, and liver cancer progression, providing a theoretical basis for targeting MYC as an ideal therapeutic target for liver cancer. We also summarize and prospect the strategies for targeting MYC, including direct and indirect approaches to abolish the oncogenic function of MYC in liver cancer.
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Affiliation(s)
- Furong Liu
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
- Hubei Key Laboratory of Hepato-Pancreato-Biliary Diseases, Wuhan, Hubei, 430030, China
- Key Laboratory of Organ Transplantation, Ministry of Education; NHC Key Laboratory of Organ Transplantation; Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, China
| | - Zhibin Liao
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
- Hubei Key Laboratory of Hepato-Pancreato-Biliary Diseases, Wuhan, Hubei, 430030, China
- Key Laboratory of Organ Transplantation, Ministry of Education; NHC Key Laboratory of Organ Transplantation; Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, China
| | - Zhanguo Zhang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China.
- Hubei Key Laboratory of Hepato-Pancreato-Biliary Diseases, Wuhan, Hubei, 430030, China.
- Key Laboratory of Organ Transplantation, Ministry of Education; NHC Key Laboratory of Organ Transplantation; Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, China.
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4
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Villanueva RA, Loyola A. Pre- and Post-Transcriptional Control of HBV Gene Expression: The Road Traveled towards the New Paradigm of HBx, Its Isoforms, and Their Diverse Functions. Biomedicines 2023; 11:1674. [PMID: 37371770 DOI: 10.3390/biomedicines11061674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/04/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
Hepatitis B virus (HBV) is an enveloped DNA human virus belonging to the Hepadnaviridae family. Perhaps its main distinguishable characteristic is the replication of its genome through a reverse transcription process. The HBV circular genome encodes only four overlapping reading frames, encoding for the main canonical proteins named core, P, surface, and X (or HBx protein). However, pre- and post-transcriptional gene regulation diversifies the full HBV proteome into diverse isoform proteins. In line with this, hepatitis B virus X protein (HBx) is a viral multifunctional and regulatory protein of 16.5 kDa, whose canonical reading frame presents two phylogenetically conserved internal in-frame translational initiation codons, and which results as well in the expression of two divergent N-terminal smaller isoforms of 8.6 and 5.8 kDa, during translation. The canonical HBx, as well as the smaller isoform proteins, displays different roles during viral replication and subcellular localizations. In this article, we reviewed the different mechanisms of pre- and post-transcriptional regulation of protein expression that take place during viral replication. We also investigated all the past and recent evidence about HBV HBx gene regulation and its divergent N-terminal isoform proteins. Evidence has been collected for over 30 years. The accumulated evidence simply strengthens the concept of a new paradigm of the canonical HBx, and its smaller divergent N-terminal isoform proteins, not only during viral replication, but also throughout cell pathogenesis.
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Affiliation(s)
| | - Alejandra Loyola
- Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago 8580702, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago 7510602, Chile
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5
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Zhang H, Li B. NIMA-related kinase 6 as an effective target inhibits the hepatocarcinogenesis and progression of hepatocellular carcinoma. Heliyon 2023; 9:e15971. [PMID: 37260886 PMCID: PMC10227323 DOI: 10.1016/j.heliyon.2023.e15971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/26/2023] [Accepted: 04/27/2023] [Indexed: 06/02/2023] Open
Abstract
Background NIMA-related kinase 6 (NEK 6) is over-expressed in some tumor cell lines and tissues. However, its expression in hepatocellular carcinoma (HCC) and its correlation with clinical features remain unclear. Methods Total RNA from HCC liver tissues, other liver specimens, and hepatic cell lines was extracted and QPCR was adopted to detect NEK6 expression. The correlation between NEK6 expression and the clinical characteristics of HCC was analyzed. Scratch assay, Transwell assay, and tumor-formation assay were used to evaluate the effects of NEK6 on the HCC progression in vitro and in vivo. Results The expression of NEK6 was up-regulated in HCC tissues and HCC cell lines: Li-7 and HepG2. The overexpression of NEK6 was correlated with hepatitis B virus infection and tumor diameter (P = 0.045). When down-regulated the expression of NEK6, both the migration and invasion capabilities of Li-7 and HepG2 cells and the growth of xenograft tumors were suppressed. (P < 0.05). Conclusions NEK6 expression was up-regulated in HCC and correlated with the progression, suggesting it might be a valuable biomarker and a potential therapeutic target for HCC.
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Affiliation(s)
- Hao Zhang
- Department of Hepatobiliary Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 610072, China
| | - Bo Li
- Department of Hepatobiliary Surgery, West China Hospital, Sichuan University, Chengdu 610041, China
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6
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Androgen receptor variant 7 exacerbates hepatocarcinogenesis in a c-MYC-driven mouse HCC model. Oncogenesis 2023; 12:4. [PMID: 36746917 PMCID: PMC9902460 DOI: 10.1038/s41389-023-00449-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 01/17/2023] [Accepted: 01/20/2023] [Indexed: 02/08/2023] Open
Abstract
Androgen receptor variant 7 (AR-V7), an AR isoform with a truncated ligand-binding domain, functions as a transcription factor in an androgen-independent manner. AR-V7 is expressed in a subpopulation of hepatocellular carcinoma (HCC), however, its role(s) in this cancer is undefined. In this study, we investigated the potential roles of AR-V7 in hepatocarcinogenesis in vivo in a c-MYC-driven mouse HCC model generated by the hydrodynamic tail-vein injection system. The impacts of AR-V7 on gene expression in mouse HCC were elucidated by RNA-seq transcriptome and ontology analyses. The results showed that AR-V7 significantly exacerbated the c-MYC-mediated oncogenesis in the livers of both sexes. The transcriptome and bioinformatics analyses revealed that AR-V7 and c-MYC synergistically altered the gene sets involved in various cancer-related biological processes, particularly in lipid and steroid/sterol metabolisms. Importantly, AR-V7 suppressed a tumor suppressor Claudin 7 expression, upregulated by c-MYC overexpression via the p53 signaling pathway. Claudin 7 overexpression significantly suppressed the c-MYC-driven HCC development under p53-deficient conditions. Our results suggest that the AR-V7 exacerbates the c-MYC-driven hepatocarcinogenesis by potentiating the oncogenic roles and minimizing the anti-oncogenic functions of c-MYC. Since AR-V7 is expressed in a subpopulation of HCC cases, it could contribute to the inter- and intra-heterogeneity of HCC.
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7
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Profiling of LINE-1-Related Genes in Hepatocellular Carcinoma. Int J Mol Sci 2019; 20:ijms20030645. [PMID: 30717368 PMCID: PMC6387036 DOI: 10.3390/ijms20030645] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 01/26/2019] [Accepted: 01/29/2019] [Indexed: 12/14/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a prime public health concern that accounts for most of the primary liver malignancies in humans. The most common etiological factor of HCC is hepatitis B virus (HBV). Despite recent advances in treatment strategies, there has been little success in improving the survival of HCC patients. To develop a novel therapeutic approach, evaluation of a working hypothesis based on different viewpoints might be important. Long interspersed element 1 (L1) retrotransposons have been suggested to play a role in HCC. However, the molecular machineries that can modulate L1 biology in HBV-related HCC have not been well-evaluated. Here, we summarize the profiles of expression and/or activation status of L1-related genes in HBV-related HCC, and HBV- and HCC-related genes that may impact L1-mediated tumorigenesis. L1 restriction factors appear to be suppressed by HBV infection. Since some of the L1 restriction factors also limit HBV, these factors may be exhausted in HBV-infected cells, which causes de-suppression of L1. Several HBV- and HCC-related genes that interact with L1 can affect oncogenic processes. Thus, L1 may be a novel prime therapeutic target for HBV-related HCC. Studies in this area will provide insights into HCC and other types of cancers.
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8
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Lee WY, Bachtiar M, Choo CCS, Lee CG. Comprehensive review of Hepatitis B Virus-associated hepatocellular carcinoma research through text mining and big data analytics. Biol Rev Camb Philos Soc 2018; 94:353-367. [PMID: 30105774 DOI: 10.1111/brv.12457] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 07/19/2018] [Accepted: 07/24/2018] [Indexed: 02/06/2023]
Abstract
PubMed was text mined to glean insights into the role of Hepatitis B virus (HBV) in hepatocellular carcinoma (HCC) from the massive number of publications (9249) available to date. Reports from ∼70 countries identified >1300 human genes associated with either the Core, Surface or X gene in HBV-associated HCC. One hundred and forty-three of these host genes, which can potentially yield 1180 biomolecular interactions, each were reported in at least three different publications to be associated with the same HBV. These 143 genes function in 137 pathways, involved mainly in the cell cycle, apoptosis, inflammation and signalling. Fourteen of these molecules, primarily transcriptional regulators or kinases, play roles in several pathways pertinent to the hallmarks of cancers. 'Chronic' was the most frequent word used across the 9249 abstracts. A key event in chronic HBV infection is the integration of HBV into the host genome. The advent of cost-effective, next-generation sequencing technology facilitated the employment of big-data analytics comprehensively to characterize HBV-host integration within HCC patients. A total of 5331 integration events were reported across seven publications, with most of these integrations observed between the Core/X gene and the introns of genes. Nearly one-quarter of the intergenic integrations are within repeats, especially long interspersed nuclear elements (LINE) repeats. Integrations within 13 genes were each reported by at least three different studies. The human gene with the most HBV integrations observed is the TERT gene where a total of 224 integrations, primarily at its promoter and within the tumour tissue, were reported by six of seven publications. This unique review, which employs state-of-the-art text-mining and data-analytics tools, represents the most complete, systematic and comprehensive review of nearly all the publications associated with HBV-associated HCC research. It provides important resources to either focus future research or develop therapeutic strategies to target key molecules reported to play important roles in key pathways of HCC, through the systematic analyses of the commonly reported molecules associated with the various HBV genes in HCC, including information about the interactions amongst these commonly reported molecules, the pathways in which they reside as well as detailed information regarding the viral and host genes associated with HBV integration in HCC patients. Hence this review, which highlights pathways and key human genes associated with HBV in HCC, may facilitate the deeper elucidation of the role of HBV in hepato-carcinogenesis, potentially leading to timely intervention against this deadly disease.
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Affiliation(s)
- Wai Yeow Lee
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119077, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 119077, Singapore
| | - Maulana Bachtiar
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119077, Singapore.,Division of Medical Sciences, Humphrey Oei Institute of Cancer Research, National Cancer Centre Singapore, 11 Hospital Drive, Singapore, 169610, Singapore
| | - Cheryl C S Choo
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 119077, Singapore.,Division of Medical Sciences, Humphrey Oei Institute of Cancer Research, National Cancer Centre Singapore, 11 Hospital Drive, Singapore, 169610, Singapore
| | - Caroline G Lee
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119077, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 119077, Singapore.,Division of Medical Sciences, Humphrey Oei Institute of Cancer Research, National Cancer Centre Singapore, 11 Hospital Drive, Singapore, 169610, Singapore.,Duke-National University of Singapore Graduate Medical School, Singapore, 169547, Singapore
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9
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Lu Z. The function of HBx in HBV-induced hepatocellular carcinoma. INFECTION INTERNATIONAL 2018. [DOI: 10.1515/ii-2017-0157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AbstractHepatocellular carcinoma (HCC) is the second cause cancer death in the world. HCC is frequently diagnosed at advanced stages with intrahepatic metstasis or vascular invasion and has a poor prognosis with a high mortality rate. In the world, hepatitis B virus (HBV) caused over 50% HCC, making it the most common carcinogen after tobacco. Notably, accumulating evidence suggests HBV X gene (HBx) play an important role in tumorigenesis of HBV-related HCC. In this review, we will summarize the functions of HBx proteins in tumorigenesis and discuss their potential implications in cancer therapy.
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Affiliation(s)
- Zhaoliang Lu
- The First Affiliated Hospital, Biomedical Translational Research Institute, Jinan University, 601 West Huangpu Avenue, Guangzhou, Guangdong 510632, China
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10
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c-MYC-Making Liver Sick: Role of c-MYC in Hepatic Cell Function, Homeostasis and Disease. Genes (Basel) 2017; 8:genes8040123. [PMID: 28422055 PMCID: PMC5406870 DOI: 10.3390/genes8040123] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/30/2017] [Accepted: 04/12/2017] [Indexed: 12/20/2022] Open
Abstract
Over 35 years ago, c-MYC, a highly pleiotropic transcription factor that regulates hepatic cell function, was identified. In recent years, a considerable increment in the number of publications has significantly shifted the way that the c-MYC function is perceived. Overexpression of c-MYC alters a wide range of roles including cell proliferation, growth, metabolism, DNA replication, cell cycle progression, cell adhesion and differentiation. The purpose of this review is to broaden the understanding of the general functions of c-MYC, to focus on c-MYC-driven pathogenesis in the liver, explain its mode of action under basal conditions and during disease, and discuss efforts to target c-MYC as a plausible therapy for liver disease.
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11
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Yamaguchi M. Involvement of regucalcin as a suppressor protein in human carcinogenesis: insight into the gene therapy. J Cancer Res Clin Oncol 2015; 141:1333-41. [PMID: 25230901 DOI: 10.1007/s00432-014-1831-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 09/09/2014] [Indexed: 12/18/2022]
Abstract
Regucalcin, which its gene is located on the X chromosome, plays a multifunctional role as a suppressor protein in cell signal transduction in various types of cells and tissues. The suppression of regucalcin gene expression has been shown to involve in carcinogenesis. Regucalcin gene expression was uniquely downregulated in carcinogenesis of rat liver in vivo, although the expression of other many genes was upregulated, indicating that endogenous regucalcin plays a suppressive role in the development of hepatocarcinogenesis. Overexpression of endogenous regucalcin was found to suppress proliferation of rat cloned hepatoma cells in vitro. Moreover, the regucalcin gene and its protein levels were demonstrated specifically to downregulate in human hepatocellular carcinoma by analysis with multiple gene expression profiles and proteomics. Regucalcin gene expression was also found to suppress in human tumor tissues including kidney, lung, brain, breast and prostate, suggesting that repressed regucalcin gene expression leads to the development of carcinogenesis in various tissues. Regucalcin may play a role as a suppressor protein in carcinogenesis. Overexpression of endogenous regucalcin is suggested to reveal preventive and therapeutic effects on carcinogenesis. Delivery of the regucalcin gene may be a novel useful tool in the gene therapy of carcinogenesis. This review will discuss regarding to an involvement of regucalcin as a suppressor protein in human carcinogenesis in insight into the gene therapy.
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Affiliation(s)
- Masayoshi Yamaguchi
- Department of Hematology and Medical Oncology, Winship Cancer Institute, Emory University School of Medicine, 1365 C Clifton Road NE, Atlanta, GA, 30322, USA,
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12
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Fiorino S, Bacchi-Reggiani L, Sabbatani S, Grizzi F, di Tommaso L, Masetti M, Fornelli A, Bondi A, de Biase D, Visani M, Cuppini A, Jovine E, Pession A. Possible role of tocopherols in the modulation of host microRNA with potential antiviral activity in patients with hepatitis B virus-related persistent infection: a systematic review. Br J Nutr 2014; 112:1751-1768. [PMID: 25325563 DOI: 10.1017/s0007114514002839] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hepatitis B virus (HBV) infection represents a serious global health problem and persistent HBV infection is associated with an increased risk of cirrhosis, hepatocellular carcinoma and liver failure. Recently, the study of the role of microRNA (miRNA) in the pathogenesis of HBV has gained considerable interest as well as new treatments against this pathogen have been approved. A few studies have investigated the antiviral activity of vitamin E (VE) in chronic HBV carriers. Herein, we review the possible role of tocopherols in the modulation of host miRNA with potential anti-HBV activity. A systematic research of the scientific literature was performed by searching the MEDLINE, Cochrane Library and EMBASE databases. The keywords used were 'HBV therapy', 'HBV treatment', 'VE antiviral effects', 'tocopherol antiviral activity', 'miRNA antiviral activity' and 'VE microRNA'. Reports describing the role of miRNA in the regulation of HBV life cycle, in vitro and in vivo available studies reporting the effects of VE on miRNA expression profiles and epigenetic networks, and clinical trials reporting the use of VE in patients with HBV-related chronic hepatitis were identified and examined. Based on the clinical results obtained in VE-treated chronic HBV carriers, we provide a reliable hypothesis for the possible role of this vitamin in the modulation of host miRNA profiles perturbed by this viral pathogen and in the regulation of some cellular miRNA with a suggested potential anti-HBV activity. This approach may contribute to the improvement of our understanding of pathogenetic mechanisms involved in HBV infection and increase the possibility of its management and treatment.
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Affiliation(s)
- S Fiorino
- Unità Operativa di Medicina Interna, Ospedale di Budrio,Via Benni 44,40065Budrio, Bologna,Italy
| | - L Bacchi-Reggiani
- Istituto di Cardiologia, Policlinico S. Orsola-Malpighi, Università degli Studi di Bologna,Bologna,Italy
| | - S Sabbatani
- Istituto di Malattie Infettive, Policlinico S. Orsola-Malpighi, Università degli Studi di Bologna,Bologna,Italy
| | - F Grizzi
- Humanitas Clinical and Research Center,Rozzano, Milano,Italy
| | - L di Tommaso
- Humanitas Clinical and Research Center,Rozzano, Milano,Italy
| | - M Masetti
- Unità Operativa di Chirurgia A, Ospedale Maggiore Bologna,Bologna,Italy
| | - A Fornelli
- Servizio di Anatomia Patologica, Ospedale Maggiore,Bologna,Italy
| | - A Bondi
- Servizio di Anatomia Patologica, Ospedale Maggiore,Bologna,Italy
| | - D de Biase
- Dipartimento di Medicina Sperimentale,Università di Bologna, Ospedale Bellaria,Bologna,Italy
| | - M Visani
- Dipartimento di Farmacia e Biotecnologie,Università di Bologna,Bologna,Italy
| | - A Cuppini
- Unità Operativa di Medicina Interna, Ospedale di Budrio,Via Benni 44,40065Budrio, Bologna,Italy
| | - E Jovine
- Unità Operativa di Chirurgia A, Ospedale Maggiore Bologna,Bologna,Italy
| | - A Pession
- Dipartimento di Farmacia e Biotecnologie,Università di Bologna,Bologna,Italy
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13
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Parpart S, Roessler S, Dong F, Rao V, Takai A, Ji J, Qin L, Ye Q, Jia H, Tang Z, Wang XW. Modulation of miR-29 expression by α-fetoprotein is linked to the hepatocellular carcinoma epigenome. Hepatology 2014; 60:872-83. [PMID: 24798303 PMCID: PMC4146718 DOI: 10.1002/hep.27200] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 04/29/2014] [Indexed: 01/09/2023]
Abstract
UNLABELLED Globally, hepatocellular carcinoma (HCC) accounts for 70%-85% of primary liver cancers and ranks as the second leading cause of male cancer death. Serum alpha-fetoprotein (AFP), normally highly expressed in the liver only during fetal development, is reactivated in 60% of HCC tumors and associated with poor patient outcome. We hypothesize that AFP+ and AFP- tumors differ biologically. Multivariable analysis in 237 HCC cases demonstrates that AFP level predicts poor survival independent of tumor stage (P<0.043). Using microarray-based global microRNA (miRNA) profiling, we found that miRNA-29 (miR-29) family members were the most significantly (P<0.001) down-regulated miRNAs in AFP+ tumors. Consistent with miR-29's role in targeting DNA methyltransferase 3A (DNMT3A), a key enzyme regulating DNA methylation, we found a significant inverse correlation (P<0.001) between miR-29 and DNMT3A gene expression, suggesting that they might be functionally antagonistic. Moreover, global DNA methylation profiling reveals that AFP+ and AFP- HCC tumors have distinct global DNA methylation patterns and that increased DNA methylation is associated with AFP+ HCC. Experimentally, we found that AFP expression in AFP- HCC cells induces cell proliferation, migration, and invasion. Overexpression of AFP, or conditioned media from AFP+ cells, inhibits miR-29a expression and induces DNMT3A expression in AFP- HCC cells. AFP also inhibited transcription of the miR-29a/b-1 locus, and this effect is mediated through c-MYC binding to the transcript of miR-29a/b-1. Furthermore, AFP expression promotes tumor growth of AFP- HCC cells in nude mice. CONCLUSION Tumor biology differs considerably between AFP+ HCC and AFP- HCC; AFP is a functional antagonist of miR-29, which may contribute to global epigenetic alterations and poor prognosis in HCC.
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Affiliation(s)
- Sonya Parpart
- Laboratory of Human Carcinogenesis, NCI, Bethesda, MD,Tumor Biology Department, Georgetown University, Washington, DC
| | | | - Fei Dong
- Laboratory of Human Carcinogenesis, NCI, Bethesda, MD
| | - Vinay Rao
- Laboratory of Human Carcinogenesis, NCI, Bethesda, MD
| | - Atsushi Takai
- Laboratory of Human Carcinogenesis, NCI, Bethesda, MD
| | - Junfang Ji
- Laboratory of Human Carcinogenesis, NCI, Bethesda, MD
| | - Lun–Xiu Qin
- Liver Cancer Institute and Zhongshan Hospital, Fudan University, Shanghai, China
| | - Qing–Hai Ye
- Liver Cancer Institute and Zhongshan Hospital, Fudan University, Shanghai, China
| | - Hu–Liang Jia
- Liver Cancer Institute and Zhongshan Hospital, Fudan University, Shanghai, China
| | - Zhao–You Tang
- Liver Cancer Institute and Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xin Wei Wang
- Laboratory of Human Carcinogenesis, NCI, Bethesda, MD,Correspondence: Xin Wei Wang, National Cancer Institute, 37 Convent Drive, Bethesda, Maryland 20892; ; Phone: 301-496-2099; Fax: 301-496-0497
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14
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Abstract
BACKGROUND Hepatocellular carcinoma (HCC) is one of the most common and deadly malignancies worldwide. The multikinase inhibitor sorafenib still remains the only approved agent for advanced HCC. In most cases, HCC develops based on advanced liver cirrhosis, whereas the underlying risk factors can be identified in the vast majority of patients. METHODS Here, we summarise and review the pathomechanisms in dependence of the underlying disease, gene signatures and frequent mutations in HCC. RESULTS Worldwide, HCC is most commonly caused by viral hepatitis B and C. It is less frequently associated with chronic exposure to toxins or hereditary liver diseases. Non-alcoholic fatty liver disease is an emerging risk factor with increasing prevalence nowadays. Emerging innovative technologies including whole-genome or -exome analyses have been applied for molecular and prognostic classifications as well as therapeutic implications. Mutations leading to activation of the Wnt pathway and inactivation of p53 were most frequently identified in HCC. CONCLUSIONS Recent advances have significantly improved our understanding of the molecular pathogenesis of HCC and its complex genetic landscape. The emerging data will open the door towards novel and more effective targeted and personalized therapies in this devastating disease.
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Affiliation(s)
- Martha M Kirstein
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
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15
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Shin JW, Chung YH. Molecular targeted therapy for hepatocellular carcinoma: current and future. World J Gastroenterol 2013; 19:6144-55. [PMID: 24115810 PMCID: PMC3787343 DOI: 10.3748/wjg.v19.i37.6144] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 07/18/2013] [Accepted: 08/04/2013] [Indexed: 02/06/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is one of the most frequent tumors worldwide. The majority of HCC cases occur in patients with chronic liver disease. Despite regular surveillance to detect small HCC in these patients, HCC is often diagnosed at an advanced stage. Because HCC is highly resistant to conventional systemic therapies, the prognosis for advanced HCC patients remains poor. The introduction of sorafenib as the standard systemic therapy has unveiled a new direction for future research regarding HCC treatment. However, given the limited efficacy of the drug, a need exists to look beyond sorafenib. Many molecular targeted agents that inhibit different pathways involved in hepatocarcinogenesis are under various phases of clinical development, and novel targets are being assessed in HCC. This review aims to summarize the efforts to target molecular components of the signaling pathways that are responsible for the development and progression of HCC and to discuss perspectives on the future direction of research.
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16
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Jung YJ, Kim JW, Park SJ, Min BY, Jang ES, Kim NY, Jeong SH, Shin CM, Lee SH, Park YS, Hwang JH, Kim N, Lee DH. c-Myc-mediated overexpression of miR-17-92 suppresses replication of hepatitis B virus in human hepatoma cells. J Med Virol 2013; 85:969-78. [PMID: 23532756 DOI: 10.1002/jmv.23534] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2013] [Indexed: 12/13/2022]
Abstract
MicroRNAs (miRNAs) regulate post-transcriptional gene expression in various physiological and pathological processes, including viral infections. The miR-17-92 cluster encodes six miRNAs (miR-17-5p, miR-18a, miR-19a, miR-19b, miR-20a, and miR-92a-1) which are transactivated by c-Myc. Because hepatitis B virus transactivates c-Myc, the interaction between the miR-17-92 cluster and HBV replication was examined in this study. Inducing HBV replication in a human hepatoma cell line increased miR-17-5p, miR-20a and miR-92a-1 expression. HBV-induced overexpression of miR-17-92 was reversed by c-Myc knockdown. Antisense peptide nucleic acids against miR-20a and miR-92a-1 augmented HBV replication. A computational analysis yielded potential binding sites for miR-20a and miR-92a-1 in the HBV genome. The direct interaction between these two miRNAs and target regions in HBV transcripts was confirmed by luciferase reporter analysis. These results demonstrated negative feedback suppression of HBV replication by the miR-17-92 polycistron.
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Affiliation(s)
- Yong Jin Jung
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea
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17
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Transcriptional regulators in hepatocarcinogenesis--key integrators of malignant transformation. J Hepatol 2012; 57:186-95. [PMID: 22446689 DOI: 10.1016/j.jhep.2011.11.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/28/2011] [Accepted: 11/30/2011] [Indexed: 12/26/2022]
Abstract
Hepatocellular carcinoma (HCC) is one of the most frequent human malignancies with poor prognosis and increasing incidence in the Western world. Only for a minority of HCC patients, surgical treatment options offer potential cure and therapeutic success of pharmacological approaches is limited. Highly specific approaches (e.g., kinase inhibitors) did not significantly improve the situation so far, possibly due to functional compensation, genetic heterogeneity of HCC, and development of resistance under selective pressure. In contrast, transcriptional regulators (especially transcription factors and co-factors) may integrate and process input signals of different (oncogenic) pathways and therefore represent cellular bottlenecks that regulate tumor cell biology. In this review, we want to summarize the current knowledge about central transcriptional regulators in human hepatocarcinogenesis and their potential as therapeutic target structures. Genomic and transcriptomic data of primary human HCC revealed that many of these factors showed up in subgroups of HCCs with a more aggressive phenotype, suggesting that aberrant activity of transcriptional regulators collect input information to promote tumor initiation and progression. Therefore, expression and dysfunction of transcription factors and co-factors may gain relevance for diagnostics and therapy of HCC.
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18
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Mason WS. Hepadnaviruses and Hepatocellular Carcinoma. CANCER ASSOCIATED VIRUSES 2012:531-569. [DOI: 10.1007/978-1-4614-0016-5_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2025]
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19
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Zhou Q, Lui VWY, Yeo W. Targeting the PI3K/Akt/mTOR pathway in hepatocellular carcinoma. Future Oncol 2011; 7:1149-1167. [PMID: 21992728 DOI: 10.2217/fon.11.95] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Despite recent advances in the understanding of the biologic basis of hepatocellular carcinoma (HCC) development, the clinical management of the disease remains a major challenge. Deregulation of the PI3K/Akt/mTOR pathway, which is a prototypic survival pathway, is increasingly implicated in HCC carcinogenesis. In this article, we detailed the role of this pathway in the pathogenesis of HCC and provide an update on the preclinical and clinical development of various agents targeting this key survival/proliferation pathway, which include various PI3K inhibitors, Akt inhibitors and mTOR inhibitors for HCC. In addition, we highlighted the therapeutic potential of combination strategy for mTOR inhibitors with conventional chemotherapy, in particular, antimicrotubule agents, other molecular targeting agents, as well as radiotherapy.
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Affiliation(s)
- Qian Zhou
- Department of Clinical Oncology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, China
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20
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Abstract
Chronic hepatitis B virus (HBV) infection has been identified as a major risk factor in hepatocellular carcinoma (HCC), which is one of the most common cancers worldwide. The pathogenesis of HBV-mediated hepatocarcinogenesis is, however, incompletely understood. Evidence suggests that the HBV X protein (HBx) plays a crucial role in HCC development. HBx is a multifunctional regulator that modulates transcription, signal transduction, cell cycle progression, apoptosis, protein degradation pathways, and genetic stability through interaction with host factors. This review describes the current state of knowledge of the molecular pathogenesis of HBV-induced HCC, with a focus on the role of HBx in hepatocarcinogenesis.
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Affiliation(s)
- Sue-Ann Ng
- University of New South Wales, Sydney, Australia.
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21
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Wu G, Yu F, Xiao Z, Xu K, Xu J, Tang W, Wang J, Song E. Hepatitis B virus X protein downregulates expression of the miR-16 family in malignant hepatocytes in vitro. Br J Cancer 2011; 105:146-53. [PMID: 21629246 PMCID: PMC3137408 DOI: 10.1038/bjc.2011.190] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 04/27/2011] [Accepted: 05/05/2011] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Hepatitis B virus X protein (HBx) is involved in the initiation and progression of hepatocellular carcinoma (HCC) by regulating the host protein-coding genes. In this study, we showed that HBx altered the expression of microRNAs (miRNAs) to promote proliferation and transformation in malignant hepatocytes in vitro. METHODS miRNA microarray and quantitative reverse-transcription polymerase chain reactions (qRT-PCRs) were performed to identify miRNAs that were differentially regulated by HBx in HCC cells. Protein, mRNA, and miRNA expression analyses; cell cycle and apoptosis analyses; loss/gain-of-function analysis; and luciferase reporter assays were performed to delineate the consequences of miR-16 family repression in HepG2 cells. RESULTS Hepatitis B virus X protein induced widespread deregulation of miRNAs in HepG2 cells, and the downregulation of the miR-16 family was reproducible in HepG2, SK-HEP-1, and Huh7 cells. CCND1, a target of the miR-16 family, was derepressed by HBx in HepG2 cells. c-Myc mediated the HBx-induced repression of miR-15a/16 in HepG2 cells. Ectopically expressed miR-15a/16 suppressed the proliferation, clonogenicity, and anchorage-independent growth of HBx-expressing HepG2 cells by arresting them in the G1 phase and inducing apoptosis, whereas reduced expression of miR-16 accelerated the growth and cell-cycle progression of HepG2 cells. CONCLUSIONS Hepatitis B virus X protein altered the in vitro expression of miRNAs in host malignant hepatocytes, particularly downregulating the miR-16 family. Repression of miR-15a/16 is c-Myc mediated and is required for the HBx-induced transformation of HepG2 cells in vitro. Therefore, miR-16 family may serve as a therapeutic target for hepatitis B virus (HBV)-associated HCC.
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Affiliation(s)
- G Wu
- Department of Hepatobiliary Surgery, Sun-Yat-Sen Memorial Hospital, Sun-Yat-Sen University, 107 Yanjiang West Road, Guangzhou 510120, People's Republic of China
| | - F Yu
- Department of Breast Surgery, Sun-Yat-Sen Memorial Hospital, Sun-Yat-Sen University, 107 Yanjiang West Road, Guangzhou 510120, People's Republic of China
| | - Z Xiao
- Department of Hepatobiliary Surgery, Sun-Yat-Sen Memorial Hospital, Sun-Yat-Sen University, 107 Yanjiang West Road, Guangzhou 510120, People's Republic of China
| | - K Xu
- Department of Hepatobiliary Surgery, Sun-Yat-Sen Memorial Hospital, Sun-Yat-Sen University, 107 Yanjiang West Road, Guangzhou 510120, People's Republic of China
| | - J Xu
- Department of Hepatobiliary Surgery, Sun-Yat-Sen Memorial Hospital, Sun-Yat-Sen University, 107 Yanjiang West Road, Guangzhou 510120, People's Republic of China
| | - W Tang
- Department of Breast Surgery, Sun-Yat-Sen Memorial Hospital, Sun-Yat-Sen University, 107 Yanjiang West Road, Guangzhou 510120, People's Republic of China
| | - J Wang
- Department of Hepatobiliary Surgery, Sun-Yat-Sen Memorial Hospital, Sun-Yat-Sen University, 107 Yanjiang West Road, Guangzhou 510120, People's Republic of China
| | - E Song
- Department of Breast Surgery, Sun-Yat-Sen Memorial Hospital, Sun-Yat-Sen University, 107 Yanjiang West Road, Guangzhou 510120, People's Republic of China
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22
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Lin CP, Liu CR, Lee CN, Chan TS, Liu HE. Targeting c-Myc as a novel approach for hepatocellular carcinoma. World J Hepatol 2010; 2:16-20. [PMID: 21160952 PMCID: PMC2999263 DOI: 10.4254/wjh.v2.i1.16] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2009] [Revised: 01/08/2010] [Accepted: 01/15/2010] [Indexed: 02/06/2023] Open
Abstract
Hepatocelluar carcinoma (HCC) is the most lethal cancer in the world. Most HCC over-express c-Myc, which plays a critical role in regulating cellular growth, differentiation and apoptosis in both normal and neoplastic cells. c-Myc is among the most frequently overexpressed genes in human cancers. Overexpression of c-Myc in hepatic cells leads to development of hepatocellular carcinoma. Here, we review the current progress in understanding physiologic function and regulation of c-Myc as well as its role in hepatic carcinogenesis and discuss the association of c-Myc activation in chronic hepatitis B infection and the upregulation of HIF-1/VEGF. We also explore the possibility of treating HCC by inhibiting c-Myc and examine the pros and cons of such an approach. Although this strategy is currently not available in clinics, with recent advances in better drug design, pharmacokinetics and pharmacogenetics, inhibition of c-Myc might become a novel therapy for HCC in the future.
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Affiliation(s)
- Che-Pin Lin
- Che-Pin Lin, Chien-Ru Liu, Department of Medicine, Taipei City Hospital, Ren-Ai Branch, Taipei 106, Taiwan
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23
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24
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Liver cell transformation in chronic HBV infection. Viruses 2009; 1:630-646. [PMID: 21994562 PMCID: PMC3185520 DOI: 10.3390/v1030630] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 10/26/2009] [Accepted: 10/29/2009] [Indexed: 12/20/2022] Open
Abstract
Epidemiological studies have provided overwhelming evidence for a causal role of chronic HBV infection in the development of hepatocellular carcinoma (HCC), but the molecular mechanisms underlying virally-induced tumorigenesis remain largely debated. In the absence of a dominant oncogene encoded by the HBV genome, indirect roles have been proposed, including insertional activation of cellular oncogenes by HBV DNA integration, induction of genetic instability by viral integration or by the regulatory protein HBx, and long term effects of viral proteins in enhancing immune-mediated liver disease. In this chapter, we discuss different models of HBV-mediated liver cell transformation based on animal systems of hepadnavirus infection as well as functional studies in hepatocyte and hepatoma cell lines. These studies might help identifying the cellular effectors connecting HBV infection and liver cell transformation.
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25
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Ma ZM, Lin X, Wang YX, Tian XC, Xie YH, Wen YM. A double-spliced defective hepatitis B virus genome derived from hepatocellular carcinoma tissue enhanced replication of full-length virus. J Med Virol 2009; 81:230-7. [PMID: 19107969 DOI: 10.1002/jmv.21393] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In hepatitis B virus (HBV) replication cycle, pregenomic RNA undergoes splicing and the reverse transcribed defective genomes can be packaged and released. Various types of spliced defective HBV genomes have been isolated from the sera and liver tissues of viral hepatitis B patients. To explore the functions of a 2.2 kb double spliced HBV variant, a 3.2 kb full-length HBV isolate (#97-34) and its 2.2 kb double-spliced HBV variant (#AP-12) from the tumor tissue of a patient with hepatocellular carcinoma (HCC) were amplified and cloned. Sequencing results showed that #AP12 had deletions in pre-S2, part of pre-S1, S genes, part of the spacer, and part of the reverse transcriptase gene, while the X gene was intact. When this defective double-spliced genome and its full-length counterpart genome were co-transfected into HepG2 cells, the former was shown to enhance the replication of the latter, both by real-time PCR and Southern blotting. When a replication incompetent clone 97-34G1881A was used to co-transfect with #AP12, #AP12 DNA was increased, indicating that replication of the wild-type virus was not the only factor involved in this observation. However, the replication enhancing competency of #AP12 was shown to require an intact HBV X expression cassette. The double-spliced defective variant might contribute to persistent HBV replication in a subpopulation of HCC patients.
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Affiliation(s)
- Zhang-Mei Ma
- Key Laboratory of Medical Molecular Virology, Shanghai Medical College, Institute of Biological Medical Sciences, Fudan University, Shanghai, China
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26
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27
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Yang L, He J, Chen L, Wang G. Hepatitis B virus X protein upregulates expression of SMYD3 and C-MYC in HepG2 cells. Med Oncol 2008; 26:445-51. [PMID: 19082926 DOI: 10.1007/s12032-008-9144-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 11/21/2008] [Indexed: 01/11/2023]
Abstract
The carcinogenic role of Hepatitis B X (HBX) in hepatocellular carcinoma (HCC) remains largely unknown. Histone H3 lysine 4 methyltransferase SMYD3 was found to be over-expressed and have a pro-carcinogenic effect in HCC. The role of HBX in regulating SMYD3 activity and the corresponding C-MYC gene in HCC carcinogenesis was investigated. SMYD3 and C-MYC expression in HBV-negative HepG2 and HBV-positive HepG2.2.15 were detected by real time PCR and Western blot. After transfection of HBX into HepG2, SMYD3 and C-MYC protein expression was detected and the apoptosis and proliferation of hepatoma cells were assayed. After SMYD3 expression in HepG2 with HBX transfection downregulated by siRNA, the corresponding C-MYC expression, cellular apoptosis, and proliferation were assayed by FACS. SMYD3 mRNA and protein and C-MYC protein were significantly higher in HepG2.2.15 than in HepG2. HBX transfection resulted in enhanced SMYD3 and C-MYC expressions, decreased cell apoptosis, and increased cell proliferation in HepG2 cells. Knocking down of SMYD3 in HepG2 with HBX transfection inhibited C-MYC expression and promoted apoptosis. These results suggest that HBX upregulates SMYD3 expression in HepG2, which may promote hepatoma development and progress. C-MYC may act as a down-stream gene in HBX-SMYD3-related hepatocarcinogenesis.
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Affiliation(s)
- Lian Yang
- Hepatobiliary Center, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Jiefang Dadao 1277, Wuhan 430022, People's Republic of China
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28
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He J, Ma ZL, Chen LB, Wang GB. SMYD3 expression differences in hepatoma cell lines with different HBV expression levels. Shijie Huaren Xiaohua Zazhi 2008; 16:2036-2039. [DOI: 10.11569/wcjd.v16.i18.2036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To evaluate correlation between histone methyltransferase SMYD3 expression in hepatoma and HBV infection.
METHODS: SMYD3 mRNA expressions and SMYD3 protein expression levels in HBV-negative HepG2 and HBV-positive hepatoma cell line HepG2.2.15 were determined using real time PCR and Western blot, respectively.
RESULTS: SMYD3 mRNA and protein levels were significantly higher in HepG2.2.15 than those in HepG2 (0.92 ± 0.12 vs 0.18 ± 0.05, 0.28 ± 0.03 vs 0.54 ± 0.05, both P < 0.01).
CONCLUSION: HBV may promote hepatoma cell malignancy through its SMYD3 up-regulating pathways.
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29
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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.
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Affiliation(s)
- M A Kern
- Pathologisches Institut, Universität Heidelberg, Im Neuenheimer Feld 220/221, 69120, Heidelberg, Deutschland.
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30
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Yan X, Chua MS, He J, So SK. Small interfering RNA targeting CDC25B inhibits liver tumor growth in vitro and in vivo. Mol Cancer 2008; 7:19. [PMID: 18269767 PMCID: PMC2276234 DOI: 10.1186/1476-4598-7-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Accepted: 02/12/2008] [Indexed: 01/09/2023] Open
Abstract
Background Using gene expression profiling, we previously identified CDC25B to be significantly highly expressed in hepatocellular carcinoma (HCC) compared to non-tumor liver. CDC25B is a cell cycle-activating phosphatase that positively regulates the activity of cyclin-dependent kinases, and is over-expressed in a variety of human malignancies. In this study, we validated the over-expression of CDC25B in HCC, and further investigated its potential as a therapeutic target for the management of HCC. Results Quantitative real-time polymerase chain reaction and immunohistochemical staining of patient samples confirmed the significant over-expression of CDC25B in HCC compared to non-tumor liver samples (P < 0.001). Thus, intefering with the expression and activity of CDC25B may be a potential way to intervene with HCC progression. We used RNA interference to study the biological effects of silencing CDC25B expression in HCC cell lines (Hep3B and Hep40), in order to validate its potential as a therapeutic target. Using small oligo siRNAs targeting the coding region of CDC25B, we effectively suppressed CDC25B expression by up to 90%. This was associatetd with significant reductions in cell growth rate, cell migration and invasion through the matrigel membrane, and caused significant cell cycle delay at the G2 phase. Finally, suppression of CDC25B significantly slowed the growth of Hep40 xenografts in nude mice. Conclusion Our data provide evidence that the inhibition of CDC25B expression and activity lead to suppression of tumor cell growth and motility, and may therefore be a feasible approach in the clinical management of HCC.
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Affiliation(s)
- Xinrui Yan
- Asian Liver Center, Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
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31
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Pang RWC, Poon RTP. From molecular biology to targeted therapies for hepatocellular carcinoma: the future is now. Oncology 2007; 72 Suppl 1:30-44. [PMID: 18087180 DOI: 10.1159/000111705] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hepatocellular carcinoma (HCC) is characterized as a highly chemoresistant cancer with no effective systemic therapy. Despite surgical or locoregional therapies, prognosis remains poor because of high tumor recurrence or tumor progression, and currently there are no well-established effective adjuvant therapies. The molecular biology of carcinogenesis and tumor progression of HCC has been increasingly understood with intense research in recent years. Several important intracellular signaling pathways such as the Ras/Raf/Mek/Erk pathway and PI3k/Akt/mTOR pathway have been recognized, and the role of several growth factors and angiogenic factors such as EGF and VEGF has been confirmed. Effective agents targeting these molecular abnormalities have been developed and widely tested in preclinical studies of HCC cell lines or xenograft models. Several agents have entered clinical trials in HCC patients, and recent data indicated that a multikinase inhibitor targeting Ras kinase and VEGFR-2, sorafenib, is effective in prolonging survival of patients with advanced HCC. The management of advanced HCC is entering the era of molecular targeting therapy, which is of particular significance for HCC in view of the lack of existing effective systemic therapy for this cancer.
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Affiliation(s)
- Roberta W C Pang
- Department of Medicine, Centre for Cancer Research, the University of Hong Kong, Hong Kong, SAR, China
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32
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Lin CP, Liu JD, Chow JM, Liu CR, Liu HE. Small-molecule c-Myc inhibitor, 10058-F4, inhibits proliferation, downregulates human telomerase reverse transcriptase and enhances chemosensitivity in human hepatocellular carcinoma cells. Anticancer Drugs 2007; 18:161-70. [PMID: 17159602 DOI: 10.1097/cad.0b013e3280109424] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
c-Myc oncogene is critical for the development of hepatocellular carcinoma. Given the successful use of small-molecule inhibitors on cancers, targeting c-Myc with small-molecule inhibitors represents a promising approach. The potential of using small-molecule c-Myc inhibitor, 10058-F4, was evaluated on hepatocellular carcinoma cell lines, HepG2 and Hep3B cells. HepG2 cells were more sensitive to 10058-F4 than Hep3B cells, as demonstrated by reduced cell viability, marked morphological changes and decreased c-Myc levels. 10058-F4 arrested the cell cycle (at G0/G1 phase) and induced apoptosis upon extended treatment. These observations might be attributable to the increased cyclin-dependent kinase inhibitor, p21, and decreased cyclin D3 levels. Besides, 10058-F4 also significantly decreased the alpha-fetoprotein levels, an indicator for hepatocellular carcinoma differentiation. We further found that 10058-F4 inhibited the transactivation of human telomerase reverse transcriptase, downregulated human telomerase reverse transcriptase expression and abrogated telomerase activity. In addition, pretreatment with 10058-F4 increased the chemosensitivity of HepG2 cells to low-dose doxorubicin, 5-fluorouracil and cisplatin. Therefore, small-molecule c-Myc inhibitors might represent a novel agent, alone or in combination with conventional chemotherapeutic agents, for anti-hepatocellular carcinoma therapy.
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Affiliation(s)
- Che-Pin Lin
- Division of Hematology-Oncology, Department of Internal Medicine, Taipei City Hospital, Ren-Ai Branch, Taipei Medical University, Taipei, Taiwan
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Pang R, Lee TKW, Poon RTP, Fan ST, Wong KB, Kwong YL, Tse E. Pin1 interacts with a specific serine-proline motif of hepatitis B virus X-protein to enhance hepatocarcinogenesis. Gastroenterology 2007; 132:1088-103. [PMID: 17383430 DOI: 10.1053/j.gastro.2006.12.030] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Accepted: 11/30/2006] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND AIMS The peptidyl prolyl isomerase Pin1 frequently is overexpressed in hepatocellular carcinoma (HCC). Hepatitis B virus (HBV) is the most common etiologic agent in HCC, and its encoded X-protein (HBx) is oncogenic and possesses a serine-proline motif that may bind Pin1. The role of Pin1 in hepatocarcinogenesis, particularly in HBV-related HCC, was investigated. METHODS Immunohistochemical staining was performed to evaluate the prevalence of Pin1 overexpression in HCCs of different etiologies. Glutathione S-transferase pull-down and co-immunoprecipitation experiments were used to validate the physical interaction between Pin1 and HBx. Reporter assay, cell proliferation assay, and xenotransplantation experiments were used to show the functional consequence and importance of Pin1-HBx interaction in hepatocarcinogenesis. RESULTS We showed preferential Pin1 overexpression in HBV-related tumors and confirmed the interaction between Pin1 and HBx at the specific serine-proline motif. Pin1 overexpression increased the protein stability of HBx. Furthermore, HBx-mediated transactivation was enhanced by co-expression of Pin1. HepG2 expressing Pin1 and HBx showed a synergistic increase in cellular proliferation, as compared with cells expressing Pin1 or HBx alone. Furthermore, concomitant expression of Pin1 and HBx in the nontumorigenic human hepatocyte cell line MIHA led to a synergistic increase in tumor growth. Finally, in Hep3B cells with suppressed Pin1 expression, HBx-enhanced tumor growth in nude mice was abrogated. CONCLUSIONS Pin1 binds HBx to enhance hepatocarcinogenesis in HBV-infected hepatocytes. The discovery of an interaction between Pin1 and HBx will further our understanding of the molecular pathogenic mechanism of HBV-related HCC in human beings.
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MESH Headings
- Amino Acid Motifs
- Animals
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Carcinoma, Hepatocellular/virology
- Cell Line, Tumor
- Cell Proliferation
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Hepatitis B/complications
- Hepatitis B/genetics
- Hepatitis B/metabolism
- Hepatitis B/pathology
- Hepatitis B/virology
- Humans
- Liver Neoplasms/genetics
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Liver Neoplasms/virology
- Liver Neoplasms, Experimental/metabolism
- Liver Neoplasms, Experimental/pathology
- Liver Neoplasms, Experimental/virology
- Mice
- Mice, Nude
- NIMA-Interacting Peptidylprolyl Isomerase
- Peptidylprolyl Isomerase/genetics
- Peptidylprolyl Isomerase/metabolism
- Phosphorylation
- Proline
- Protein Binding
- Proto-Oncogene Proteins c-myc/genetics
- Proto-Oncogene Proteins c-myc/metabolism
- RNA, Messenger/metabolism
- Reproducibility of Results
- Serine
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcription Factor RelA/genetics
- Transcription Factor RelA/metabolism
- Transcription, Genetic
- Transcriptional Activation
- Transfection
- Transplantation, Heterologous
- Up-Regulation
- Viral Regulatory and Accessory Proteins
- bcl-X Protein/genetics
- bcl-X Protein/metabolism
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Affiliation(s)
- Roberta Pang
- Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong
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Feitelson MA, Lee J. Hepatitis B virus integration, fragile sites, and hepatocarcinogenesis. Cancer Lett 2006; 252:157-70. [PMID: 17188425 DOI: 10.1016/j.canlet.2006.11.010] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Revised: 11/08/2006] [Accepted: 11/13/2006] [Indexed: 12/31/2022]
Abstract
Chronic liver disease associated with long term hepatitis B virus (HBV) infection contributes importantly to the development of hepatocellular carcinoma (HCC). A salient feature of these chronic infections is the integration of subgenomic HBV DNA fragments into many different locations within the host DNA, suggesting that integration is random. Although this may promote genetic instability during liver regeneration which accompanies a bout of chronic liver disease, the actual role of integrated HBV DNA in hepatocarcinogenesis is uncertain. Importantly, most integration events retain the HBV open reading frame encoding the HBx antigen (HBxAg), which is the virus contribution to HCC. In addition, many integration events reported in the literature occur near or within fragile sites or other cancer associated regions of the human genome that are prone to instability in tumor development and progression. Genetic instability associated with integration potentially alters the expression of oncogenes, tumor suppressor genes, and microRNAs (miRNAs) that may contribute importantly to tumorigenesis. If so, then selected integration events may alter pathways that are rate limiting in hepatocarcinogenesis, thereby providing targets with diagnostic/prognostic potential and for therapeutic intervention.
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Affiliation(s)
- Mark A Feitelson
- Department of Pathology, Anatomy and Cell Biology, Kimmel Cancer Center, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA.
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35
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Lian Z, Liu J, Li L, Li X, Clayton M, Wu MC, Wang HY, Arbuthnot P, Kew M, Fan D, Feitelson MA. Enhanced cell survival of Hep3B cells by the hepatitis B x antigen effector, URG11, is associated with upregulation of beta-catenin. Hepatology 2006; 43:415-24. [PMID: 16496348 DOI: 10.1002/hep.21053] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intrahepatic expression of hepatitis B x antigen (HBxAg) is associated with the development of hepatocellular carcinoma (HCC), perhaps through trans-activation of selected cellular genes. When this was examined by PowerBlot analysis, upregulated levels of beta-catenin and several known beta-catenin effectors were observed in HBxAg-positive compared with HBxAg-negative HepG2 cells. When HBxAg was introduced into Hep3B cells, upregulated expression of wild-type beta-catenin was observed. This was also observed in Hep3B cells overexpressing the HBxAg upregulated gene, URG11. Upregulated expression of URG11 and beta-catenin correlated with HBxAg trans-activation function. Transient transfection assays with fragments of the beta-catenin promoter showed that it was activated by both HBxAg and URG11 and inhibited by URG11-specific small inhibitory RNA. The latter also inhibited the growth of Hep3BX cells in a serum-free medium, which correlated with depressed levels of beta-catenin. Activation of beta-catenin effector genes was observed in cells stably expressing HBxAg or overexpressing URG11 compared with control cells transfected with the pTOPFLASH reporter plasmid. Extensive costaining between HBxAg, URG11, and beta-catenin was observed in infected liver and HCC nodules, suggesting a close relationship in vivo. In conclusion, wild-type beta-catenin is activated by HBxAg, in part, through the upregulated expression of the HBxAg effector URG11. URG11 stimulates the beta-catenin promoter and hepatocellular growth and survival. These observations also suggest that URG11 may be a regulatory element in the beta-catenin signaling pathway and may be a target for chemoprevention of HCC.
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Affiliation(s)
- Zhaorui Lian
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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36
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Kalra N, Kumar V. The X protein of hepatitis B virus binds to the F box protein Skp2 and inhibits the ubiquitination and proteasomal degradation of c-Myc. FEBS Lett 2005; 580:431-6. [PMID: 16376880 DOI: 10.1016/j.febslet.2005.12.034] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2005] [Revised: 12/05/2005] [Accepted: 12/10/2005] [Indexed: 12/17/2022]
Abstract
The HBx protein of hepatitis B virus is involved in deregulation of cell cycle and development of hepatocellular carcinoma. Since c-Myc also plays an important role in cell proliferation and tumor development, we studied its regulation by HBx in a human hepatoma cell line. Co-expression of HBx and c-Myc resulted in increased stability of intracellular c-Myc. HBx blocked the ubiquitination of Myc through a direct interaction with the F box region of Skp2 and destabilization of the SCF(Skp2) complex. We suggest that sustained presence of c-Myc combined with mitogenic activity inherent to HBx may be associated with cell cycle deregulation and transformation.
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Affiliation(s)
- Neetu Kalra
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India
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37
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Pang R, Tse E, Poon RTP. Molecular pathways in hepatocellular carcinoma. Cancer Lett 2005; 240:157-69. [PMID: 16239065 DOI: 10.1016/j.canlet.2005.08.031] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Accepted: 08/31/2005] [Indexed: 01/18/2023]
Abstract
Research over the past decade has unraveled important molecular pathways involved in hepatocellular carcinoma (HCC), and several chromosomal and genetic aberrations have been identified to be responsible for initiation of the carcinogenic process. HBx protein and HCV core protein appear to play a pivotal role in hepatocarcinogenesis related to hepatitis B virus and hepatitis C virus, respectively. These viral oncoproteins allow cells to bypass some of the multi-steps in hepatocarcinogenesis, accounting for the etiological role of the two viruses in HCC. Understanding of the molecular pathways of HCC facilitates the development of novel molecular strategies for chemoprevention and therapy of HCC.
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Affiliation(s)
- Roberta Pang
- Department of Medicine, Centre for Cancer Research, The University of Hong Kong, Pokfulam, Hong Kong, China
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38
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39
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Zhang SJ, Chen HY, Chen ZX, Wang XZ. Possible mechanism for hepatitis B virus X gene to induce apoptosis of hepatocytes. World J Gastroenterol 2005; 11:4351-6. [PMID: 16038033 PMCID: PMC4434661 DOI: 10.3748/wjg.v11.i28.4351] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [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 investigate the possible mechanism for HBV X gene to induce apoptosis of hepatocyte HL-7702 cells.
METHODS: HBV X gene eukaryon expression vector pcDNA3-X was established and transfected into HL-7702 cells by lipid-mediated transfection, including transient and stable transfection. Positive clones were screened by incubating in the selective medium with 600 mg/mL G418 and named HL-7702/HBV-encoded X protein (HBx) cells. The expressions of Fas/FasL, Bax/Bcl-2, and c-myc mRNA were measured by semi-quantitative RT-PCR in HL-7702/HBx and control group, respectively.
RESULTS: RT-PCR analysis confirmed that HBV X gene was transfected into HL-7702 cells successfully. By semi-quantitative RT-PCR analysis, Bax and c-myc mRNA levels in HL-7702/HBx cells of transient transfection were significantly higher than those in control, FasL and c-myc mRNA levels in HL-7702/HBx cells of stable transfection were significantly higher than those in control, whereas the Bcl-2 mRNA levels in HL-7702/HBx cells of transient and stable transfection were significantly lower than those in control.
CONCLUSION: HBV X gene may promote the apoptosis of hepatocytes by regulating the expressions of Fas/FasL, Bax/Bcl-2, and c-myc gene in a dose-dependent manner.
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Affiliation(s)
- Sheng-Jun Zhang
- Department of Gastroenterology, Union Hospital of Fujian Medical University, Fuzhou 350001, Fujian Province, China
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40
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Rui E, Moura PRD, Gonçalves KDA, Kobarg J. Expression and spectroscopic analysis of a mutant hepatitis B virus onco-protein HBx without cysteine residues. J Virol Methods 2005; 126:65-74. [PMID: 15847920 DOI: 10.1016/j.jviromet.2005.01.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Revised: 01/26/2005] [Accepted: 01/26/2005] [Indexed: 02/07/2023]
Abstract
Chronic infection of the hepatitis B virus (HBV) is one of the causes leading to liver cancer. The 3.2kb genome of HBV encodes four proteins: core antigen, surface antigen, a DNA polymerase and the X protein (HBx). The biological functions of HBx are not fully understood. It has been shown that HBx is a potent trans-activator, which activates transcription of many cellular and viral promoters indirectly via protein-protein interactions. These transactivating activities of HBx may contribute to the development of hepatocellular carcinoma. In this paper a truncated mini-HBx(-Cys) (18-142) protein, where the cysteines had been either deleted or substituted by serines, was constructed by site-directed mutagenesis and overexpressed as a 6xHis fusion protein in Escherichia coli. The 6xHis-mini-HBx(-Cys) protein was isolated from inclusion bodies, purified by Ni-affinity chromatography under denaturing conditions and refolded by sequential dialysis. The structure of the 6xHis-mini-HBx(-Cys) protein was analyzed by circular dichroism, fluorescence and one-dimensional NMR spectroscopic assays. The data presented here suggest that HBx is unstructured but has a propensity to gain secondary structure under specific experimental conditions. Its conformational flexibility might partially explain its functional complexity, namely its capacity to interact with a wide array of signaling proteins, transcriptional regulators and nucleic acids.
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Affiliation(s)
- Edmilson Rui
- Centro de Biologia Molecular Estrutural, Laboratório Nacional de Luz Síncrotron, Rua Giuseppe Máximo Scolfaro 10.000, CP 6192, Campinas, SP, CEP 13084-971, Brazil
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41
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42
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43
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44
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Kwun HJ, Jang KL. Natural variants of hepatitis B virus X protein have differential effects on the expression of cyclin-dependent kinase inhibitor p21 gene. Nucleic Acids Res 2004; 32:2202-13. [PMID: 15107488 PMCID: PMC407832 DOI: 10.1093/nar/gkh553] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Despite the extensive studies on the roles of hepatitis B virus X protein (HBx), the effects of HBx on the important cellular processes such as cell growth, cell transformation and apoptosis remain controversial. Our previous study showed that the balance between p53-dependent activation and p53-independent repression by HBx determines the expression level of cyclin-dependent kinase inhibitor p21. In the present study, we further demonstrate that HBx natural variants have differential effects on p21 expression. The critical sites in HBx were identified as residues Ser-101 for activation and Met-130 for repression, respectively. The HBx variants with Ser-101 instead of Pro-101 stabilized p53 more efficiently, probably by protecting it from the MDM2-mediated degradation. On the other hand, the Met-130-containing HBx strongly repressed p21 expression by inhibiting Sp1 activity. Overall, the effect of HBx on p21 expression seems to be determined by the balance between the opposite activities. Depending on their potentials to regulate p21 expression, HBx variants showed different effects on the cell cycle progression, and eventually on the cell growth rate, implicating its biological significance. The present study may provide a clue to explaining the contradictory results related to cell growth regulation by HBx as well as to understanding the progression of hepatic diseases in HBV-positive patients.
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Affiliation(s)
- Hyun Jin Kwun
- Department of Microbiology, College of Natural Sciences, Pusan National University, Busan 609-735, Korea
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45
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N/A. N/A. Shijie Huaren Xiaohua Zazhi 2004; 12:938-940. [DOI: 10.11569/wcjd.v12.i4.938] [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
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Kaplan DE, Reddy KR. Rising incidence of hepatocellular carcinoma: the role of hepatitis B and C; the impact on transplantation and outcomes. Clin Liver Dis 2003; 7:683-714. [PMID: 14509534 DOI: 10.1016/s1089-3261(03)00060-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatocellular carcinoma caused by hepatitis B and hepatitis C are global scourges but are likely to peak in incidence in the next 2 decades and then decline. Universal vaccination has been effective in stemming the incidence of chronic hepatitis B and early-onset HCC in regions of high endemicity where implemented, but preventive measures in HCV are not yet available. After the attrition of older affected generations, the incidence of HCC will likely decline rapidly. While no vaccine is currently available for hepatitis C, cases are projected to peak and decline because of a marked reduction in transmission as a result of behavioral modification and safeguarding of blood supplies. Until these epidemiologic projections come to pass, management of hepatocellular carcinoma will continue to become a progressively more frequently encountered clinical challenge. Therapy for chronic hepatitis may ameliorate but will not eliminate the development of tumors. The demand for orthotopic liver transplantation will continue to climb, and palliative therapies for non-resectable cases will require studies aimed at optimization of benefit. LDLT may remain an option for high-risk patients affording tumor-free survival for some otherwise terminal patients.
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Affiliation(s)
- David E Kaplan
- Division of Gastroenterology and Hepatology, University of Pennsylvania School of Medicine, 3 Raydin, 3400 Spruce Street, Philadelphia, PA 19104, USA
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47
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Leach JK, Qiao L, Fang Y, Han SLY, Gilfor D, Fisher PB, Grant S, Hylemon PB, Peterson D, Dent P. Regulation of p21 and p27 expression by the hepatitis B virus X protein and the alternate initiation site X proteins, AUG2 and AUG3. J Gastroenterol Hepatol 2003; 18:376-85. [PMID: 12653885 DOI: 10.1046/j.1440-1746.2003.02990.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND The hepatitis B virus X gene has three in-frame start codons encoding the pX, AUG2 and AUG3 proteins. The AUG2 and AUG3 genes are 5'-truncated in respect to the full-length pX gene; however, all three genes terminate at the same stop codon. The activity of pX as an oncogene is well characterized; however, less is known about the AUG2 and AUG3 proteins. METHODS The effects of pX, AUG2 and AUG3 on p21Cip,1/WAF,1/MDA6 and p27Kip-1 cyclin kinase inhibitor (CKI) protein expression, and the impact they have on proliferation, were investigated in CHO K-1 cells. CHO K-1 cells were chosen because they can be transfected at 100% efficiency. RESULTS p21- and p27-luciferase reporter expression is modulated by increasing doses of the hepatitis B X proteins. At low concentrations of pX or AUG2, p21- and p27-luciferase activity was increased, and at high concentrations, p21- and p27-luciferase activity was decreased. Expression of the AUG3 gene showed a different profile: it was increasingly stimulatory with dose for both promoters. Western blot analyses demonstrated that p21 and p27 protein levels were modulated as predicted based on data generated in the promoter-luciferase experiments. Tritiated thymidine labeling of DNA showed biphasic kinetics of incorporation in the presence of varying pX and AUG2 concentrations, whereas labeling decreased with AUG3 concentration. The growth inhibitory effect of pX expression was reduced by antisense ablation of either p21 or p27. CONCLUSIONS The relative expression level of pX, AUG2, and AUG3 impacts on CKI expression and cell proliferation. Our findings may explain why divergent effects of pX expression on growth have been observed by different groups, which may be related to relative pX expression levels.
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Affiliation(s)
- J Kevin Leach
- Departments of Radiation Oncology, Richmond Commonwealth University, Richmond, USA
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48
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Lara-Pezzi E, Moreno-Otero R, López-Cabrera M. Implicación de la proteína HBx del virus de la hepatitis B en la respuesta inmune y la progresión tumoral. GASTROENTEROLOGIA Y HEPATOLOGIA 2003; 26:552-61. [PMID: 14642243 DOI: 10.1016/s0210-5705(03)70412-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- E Lara-Pezzi
- Unidad de Biología Molecular, Hospital Universitario de La Princesa, Madrid, España
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49
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Nijhara R, Jana SS, Goswami SK, Kumar V, Sarkar DP. An internal segment (residues 58-119) of the hepatitis B virus X protein is sufficient to activate MAP kinase pathways in mouse liver. FEBS Lett 2001; 504:59-64. [PMID: 11522297 DOI: 10.1016/s0014-5793(01)02773-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The human hepatitis B virus X protein (HBx) is known as a dual-specificity transactivator stimulating the transcriptional machinery in the nucleus and signal transduction pathways in the cytoplasm. HBx-induced activation of mitogen-activated protein kinase (MAPK) signaling cascades is considered to play an important role in hepatitis B virus-mediated hepatocarcinogenesis. Herein, we have identified the regions of HBx that are crucial for activating such signaling cascades in vivo. A truncated mutant incorporating regions C-E (amino acids 58-140) was as effective as the full-length HBx in activating MAPKs and enhancing activator protein-1 binding activity. While deletion of region C (amino acids 58-84) or D (amino acids 85-119) led to a drastic loss of function, region E (amino acids 120-140) was dispensable for the activation of signaling cascades. Overall, these findings provide the first evidence for the requirement of domain 58-119 of HBx in transmitting mitogenic signals to the nucleus in vivo.
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Affiliation(s)
- R Nijhara
- Department of Biochemistry, University of Delhi South Campus, Benito Juarez, New Delhi, India
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50
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Abstract
Chronic hepatitis B virus (HBV) infection is a major global cause of hepatocellular carcinoma (HCC). Individuals who are chronic carriers have a greater than 100-fold increased relative risk of developing the tumour. Several mechanisms of HBV-induced HCC have been proposed. Integration of HBV DNA into the genome of hepatocytes occurs commonly, although integration at cellular sites that are important for regulation of hepatocyte proliferation appears to be a rare event. Functions of the HBx protein are also potentially oncogenic. These include transcriptional activation of cellular growth regulatory genes, modulation of apoptosis and inhibition of nucleotide excision repair of damaged cellular DNA. The effects of HBx are mediated by interaction with cellular proteins and activation of cell signalling pathways. Variations in HBV genome sequences may be important in hepatocarcinogenesis, although their significance has not yet been completely elucidated. Necroinflammatory hepatic disease, which often accompanies chronic HBV infection, may contribute indirectly to hepatocyte transformation in a number of ways, including by facilitating HBV DNA integration, predisposing to the acquisition of cellular mutations and generating mutagenic oxygen reactive species. Although HCC is a malignancy with a poor prognosis, the availability of an effective vaccine against HBV infection, and its inclusion in the Expanded Programme of Immunization of many countries, augurs well for the eventual elimination of HBV-associated HCC.
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Affiliation(s)
- P Arbuthnot
- Department of Molecular Medicine and Haematology and Molecular Hepatology Research Unit, Department of Medicine, University of the Witwatersrand Medical School, 7 York Road, Parktown 2193, South Africa
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