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Pietropaolo V, Prezioso C, Moens U. Role of Virus-Induced Host Cell Epigenetic Changes in Cancer. Int J Mol Sci 2021; 22:ijms22158346. [PMID: 34361112 PMCID: PMC8346956 DOI: 10.3390/ijms22158346] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 12/12/2022] Open
Abstract
The tumor viruses human T-lymphotropic virus 1 (HTLV-1), hepatitis C virus (HCV), Merkel cell polyomavirus (MCPyV), high-risk human papillomaviruses (HR-HPVs), Epstein-Barr virus (EBV), Kaposi’s sarcoma-associated herpes virus (KSHV) and hepatitis B virus (HBV) account for approximately 15% of all human cancers. Although the oncoproteins of these tumor viruses display no sequence similarity to one another, they use the same mechanisms to convey cancer hallmarks on the infected cell. Perturbed gene expression is one of the underlying mechanisms to induce cancer hallmarks. Epigenetic processes, including DNA methylation, histone modification and chromatin remodeling, microRNA, long noncoding RNA, and circular RNA affect gene expression without introducing changes in the DNA sequence. Increasing evidence demonstrates that oncoviruses cause epigenetic modifications, which play a pivotal role in carcinogenesis. In this review, recent advances in the role of host cell epigenetic changes in virus-induced cancers are summarized.
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Affiliation(s)
- Valeria Pietropaolo
- Department of Public Health and Infectious Diseases, “Sapienza” University, 00185 Rome, Italy;
- Correspondence: (V.P.); (U.M.)
| | - Carla Prezioso
- Department of Public Health and Infectious Diseases, “Sapienza” University, 00185 Rome, Italy;
- IRCSS San Raffaele Roma, Microbiology of Chronic Neuro-Degenerative Pathologies, 00161 Rome, Italy
| | - Ugo Moens
- Molecular Inflammation Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø—The Arctic University of Norway, 9037 Tromsø, Norway
- Correspondence: (V.P.); (U.M.)
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2
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Yu J, Wang N, Gong Z, Liu L, Yang S, Chen GG, Lai PBS. Cytochrome P450 1A2 overcomes nuclear factor kappa B-mediated sorafenib resistance in hepatocellular carcinoma. Oncogene 2020; 40:492-507. [PMID: 33184472 DOI: 10.1038/s41388-020-01545-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 02/06/2023]
Abstract
Sorafenib resistance has become the main obstacle in the effective treatment of advanced hepatocellular carcinoma (HCC) patients. Activation of nuclear factor kappa B (NF-κB) is a newly identified mechanism that contributes to desensitized sorafenib. Cytochrome P450 1A2 (CYP1A2) functions as a tumor suppressor in HCC and its expression is negatively associated with NF-κB in the liver. This study aimed to study whether CYP1A2 could overcome sorafenib resistance. To investigate whether CYP1A2 and NF-κB p65 played roles in sorafenib desensitization, we established sorafenib-resistant (SR) HCC cells. SR cells decreased the expression of CYP1A2 along with the upregulation of NF-κB p65. CYP1A2 overexpression attenuated SR cell proliferation, increased sorafenib sensitivity, and inhibited the NF-κB pathway, whereas CYP1A2 silence showed opposite effects. Sorafenib, in combination with omeprazole, a CYP1A2 inducer, significantly hindered the growth and invasion of SR cells in vitro as well as decreased the tumor growth in vivo. The combination treatment markedly increased CYP1A2 expression and inhibited the sorafenib-induced NF-κB signaling. In addition, the overexpression of NF-κB p65 stimulated the SR cell growth and desensitized sorafenib in SR cells, where CYP1A2 overexpression reversed the phenomenon. Lastly, the majority of HCC tissue samples displayed decreased CYP1A2 but increased NF-κB p65 protein expression. Collectively, CYP1A2 can sensitize SR cells to sorafenib via inhibiting NF-κB p65 axis. Omeprazole in combination with sorafenib exerts a synergistic effect in alleviating acquired sorafenib resistance.
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Affiliation(s)
- Jianqing Yu
- Department of Surgery, Faculty of Medicine, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Nuozhou Wang
- Department of Surgery, Faculty of Medicine, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Zhongqin Gong
- Department of Surgery, Faculty of Medicine, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Liping Liu
- Department of Hepatobiliary and Pancreas Surgery, the Second Clinical Medical College of Jinan University (Shenzhen People's Hospital), Shenzhen, 524000, Guangdong, China
| | - Shengli Yang
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - George Gong Chen
- Department of Surgery, Faculty of Medicine, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China. .,Department of Otorhinolaryngology, Head and Neck Surgery, Faculty of Medicine, Prince of Walves Hospital, The Chinese University of Hong Kong, Hong Kong, China. .,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, Guangdong, China.
| | - Paul Bo San Lai
- Department of Surgery, Faculty of Medicine, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China.
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Lee YM, Kim S, Park RY, Kim YS. Hepatitis B Virus-X Downregulates Expression of Selenium Binding Protein 1. Viruses 2020; 12:v12050565. [PMID: 32443734 PMCID: PMC7291177 DOI: 10.3390/v12050565] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 05/15/2020] [Accepted: 05/18/2020] [Indexed: 02/06/2023] Open
Abstract
Selenium binding protein 1 (SELENBP1) has been known to be reduced in various types cancer, and epigenetic change is shown to be likely to account for the reduction of SELNEBP1 expression. With cDNA microarray comparative analysis, we found that SELENBP1 is markedly decreased in hepatitis B virus-X (HBx)-expressing cells. To clarify the effect of HBx on SELENBP1 expression, we compared the expression levels of SELENBP1 mRNA and protein by semi-quantitative RT-PCR, Northern blot, and Western blot. As expected, SELENBP1 expression was shown to be reduced in cells expressing HBx, and reporter gene analysis showed that the SELENBP1 promoter is repressed by HBx. In addition, the stepwise deletion of 5′ flanking promoter sequences resulted in a gradual decrease in basal promoter activity and inhibition of SELENBP1 expression by HBx. Moreover, immunohistochemistry on tissue microarrays containing 60 pairs of human liver tissue showed decreased intensity of SELENBP1 in tumor tissues as compared with their matched non-tumor liver tissues. Taken together, our findings suggest that inhibition of SELENBP1 expression by HBx might act as one of the causes in the development of hepatocellular carcinoma caused by HBV infection.
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Affiliation(s)
- Young-Man Lee
- Dasan Undergraduate College, Ajou University, Suwon 16499, Korea;
| | - Soojin Kim
- Graduate School of New Drug Discovery & Development, Chungnam National University, Daejeon 34134, Korea;
| | - Ran-Young Park
- Department of Smart Food & Drugs, Inje University, Gimhae 50834, Korea;
| | - Yeon-Soo Kim
- Graduate School of New Drug Discovery & Development, Chungnam National University, Daejeon 34134, Korea;
- Correspondence: ; Tel.: +82-42-821-8631
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4
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Chen T, Pei J, Wang J, Luo R, Liu L, Wang L, Jia H. HBx-related long non-coding RNA 01152 promotes cell proliferation and survival by IL-23 in hepatocellular carcinoma. Biomed Pharmacother 2019; 115:108877. [PMID: 31054511 DOI: 10.1016/j.biopha.2019.108877] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 04/05/2019] [Accepted: 04/11/2019] [Indexed: 02/06/2023] Open
Abstract
Accumulating evidence suggests that long-noncoding RNA (lncRNA) plays important roles in hepatitis B virus (HBV) infections. However, the mechanism underlying how lncRNA regulate hepatocellular carcinoma process remains largely unknown. In this study we found that the expression of LINC01152 was significantly increased in HBV positive HCC tissues and cells and was induced by HBx in vitro. The overexpression of LINC01152 could increases HCC cell proliferation and promotes tumor formation in nude mice. Mechanistically, HBx could increase the transcription of LINC01152. Elevated LINC01152 binds to the promoter region of IL-23, promoting its transcriptional activity and upregulating the levels of Stat3 and p-Stat3. Our findings suggest that LINC01152 plays an important role in HBV-related hepatocellular carcinoma development and may serve as a therapeutic marker for hepatocellular carcinoma.
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Affiliation(s)
- Tianshi Chen
- Department of infectious diseases, Shanxi provincial people's hospital, Taiyuan 030012, China
| | - Jinxian Pei
- Department of infectious diseases, Shanxi provincial people's hospital, Taiyuan 030012, China
| | - Jinjiang Wang
- Department of infectious diseases, Shanxi provincial people's hospital, Taiyuan 030012, China
| | - Ruili Luo
- Department of infectious diseases, Shanxi provincial people's hospital, Taiyuan 030012, China
| | - Lina Liu
- Shanghai Basilica clinic, 88 Caoxi North Road, Shanghai 200030, China.
| | - Ling Wang
- Shanghai Basilica clinic, 88 Caoxi North Road, Shanghai 200030, China.
| | - Hao Jia
- Faculty of Basic Medicine, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China.
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Peroxiredoxin 1, a Novel HBx-Interacting Protein, Interacts with Exosome Component 5 and Negatively Regulates Hepatitis B Virus (HBV) Propagation through Degradation of HBV RNA. J Virol 2019; 93:JVI.02203-18. [PMID: 30567989 DOI: 10.1128/jvi.02203-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 12/12/2018] [Indexed: 12/20/2022] Open
Abstract
Hepatitis B virus (HBV) infection is a major risk factor for the development of chronic liver diseases, including cirrhosis and hepatocellular carcinoma (HCC). A growing body of evidence suggests that HBV X protein (HBx) plays a crucial role in viral replication and HCC development. Here, we identified peroxiredoxin 1 (Prdx1), a cellular hydrogen peroxide scavenger, as a novel HBx-interacting protein. Coimmunoprecipitation analysis coupled with site-directed mutagenesis revealed that the region from amino acids 17 to 20 of the HBx, particularly HBx Cys17, is responsible for the interaction with Prdx1. Knockdown of Prdx1 by siRNA significantly increased the levels of intracellular HBV RNA, HBV antigens, and extracellular HBV DNA, whereas knockdown of Prdx1 did not increase the activities of HBV core, enhancer I (Enh1)/X, preS1, and preS2/S promoters. Kinetic analysis of HBV RNA showed that knockdown of Prdx1 inhibited HBV RNA decay, suggesting that Prdx1 reduces HBV RNA levels posttranscriptionally. The RNA coimmunoprecipitation assay revealed that Prdx1 interacted with HBV RNA. The exosome component 5 (Exosc5), a member of the RNA exosome complexes, was coimmunoprecipitated with Prdx1, suggesting its role in regulation of HBV RNA stability. Taken together, these results suggest that Prdx1 and Exosc5 play crucial roles in host defense mechanisms against HBV infection.IMPORTANCE Hepatitis B virus (HBV) infection is a major global health problem. HBx plays important roles in HBV replication and viral carcinogenesis through its interaction with host factors. In this study, we identified Prdx1 as a novel HBx-binding protein. We provide evidence suggesting that Prdx1 promotes HBV RNA decay through interaction with HBV RNA and Exosc5, leading to downregulation of HBV RNA. These results suggest that Prdx1 negatively regulates HBV propagation. Our findings may shed new light on the roles of Prdx1 and Exosc5 in host defense mechanisms in HBV infection.
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6
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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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Swamy SG, Kameshwar VH, Shubha PB, Looi CY, Shanmugam MK, Arfuso F, Dharmarajan A, Sethi G, Shivananju NS, Bishayee A. Targeting multiple oncogenic pathways for the treatment of hepatocellular carcinoma. Target Oncol 2017; 12:1-10. [PMID: 27510230 DOI: 10.1007/s11523-016-0452-7] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hepatocellular carcinoma (HCC) is one of the most common forms of liver cancer diagnosed worldwide. HCC occurs due to chronic liver disease and is often diagnosed at advanced stages. Chemotherapeutic agents such as doxorubicin are currently used as first-line agents for HCC therapy, but these are non-selective cytotoxic molecules with significant side effects. Sorafenib, a multi-targeted tyrosine kinase inhibitor, is the only approved targeted drug for HCC patients. However, due to adverse side effects and limited efficacy, there is a need for the identification of novel pharmacological drugs beyond sorafenib. Several agents that target and inhibit various signaling pathways involved in HCC are currently being assessed for HCC treatment. In the present review article, we summarize the diverse signal transduction pathways responsible for initiation as well as progression of HCC and also the potential anticancer effects of selected targeted therapies that can be employed for HCC therapy.
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Affiliation(s)
- Supritha G Swamy
- Department of Biotechnology, JSS Science and Technology University, JSS Technical Institutions Campus, Mysore, Karnataka, 570006, India
| | - Vivek H Kameshwar
- Department of Biotechnology, JSS Science and Technology University, JSS Technical Institutions Campus, Mysore, Karnataka, 570006, India
| | - Priya B Shubha
- Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore, 570 006, Karnataka, India
| | - Chung Yeng Looi
- Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - Muthu K Shanmugam
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Singapore
| | - Frank Arfuso
- School of Biomedical Sciences, Curtin Health Innovation Research Institute, Biosciences Research Precinct, Curtin University, Bentley, Western Australia, 6009, Australia
| | - Arunasalam Dharmarajan
- School of Biomedical Sciences, Curtin Health Innovation Research Institute, Biosciences Research Precinct, Curtin University, Bentley, Western Australia, 6009, Australia
| | - Gautam Sethi
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Singapore
- School of Biomedical Sciences, Curtin Health Innovation Research Institute, Biosciences Research Precinct, Curtin University, Bentley, Western Australia, 6009, Australia
| | - Nanjunda Swamy Shivananju
- Department of Biotechnology, JSS Science and Technology University, JSS Technical Institutions Campus, Mysore, Karnataka, 570006, India.
| | - Anupam Bishayee
- Department of Pharmaceutical Sciences, College of Pharmacy, Larkin Health Sciences Institute, 18301 N. Miami Avenue, Miami, FL, 33169, USA.
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Lee WP, Lan KH, Li CP, Chao Y, Lin HC, Lee SD. Oncogenic circuit constituted by Ser31-HBx and Akt increases risks of chronic hepatitis and hepatocellular carcinoma. Biochim Biophys Acta Mol Basis Dis 2016; 1862:837-849. [PMID: 26791804 DOI: 10.1016/j.bbadis.2015.12.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 11/29/2015] [Accepted: 12/16/2015] [Indexed: 01/27/2023]
Abstract
The X protein of hepatitis B virus (HBx) has been specifically implicated in the development of hepatocellular carcinoma (HCC). Clinical associations of HBx isoforms with chronic hepatitis and HCC have not been well studied. HBx has two roles in liver cells, namely pro-apoptotic and anti-apoptotic. In this report, we examined the role of Ser31-HBx in HCC and chronic hepatitis. Using the case-control study, we determined risks of chronic hepatitis and HCC conferred by hepatitis B virus (HBV) containing Ser31-HBx that was phosphorylated by Akt. Ser31-HBx isoforms conferred 3.23-fold risk of HCC in male and 3.36-fold risk in female. Ser31 isoforms were associated with 3.12-fold risk of chronic hepatitis and 3.43-fold risk of cirrhosis and also associated with higher HBV viral load and replication efficiency and lower rate of HBe loss. To determine the mechanism, we found that Ser31-HBx constituted an oncogenic circuit with Akt and cooperated with ras to transform NIH3T3 cells in contrast to non-Ser31-HBxs that did not transduce oncogenic signals. Our results give a clue to account for an underlying cause of HBx-mediated hepatocarcinogenesis. It appears that Ser31 phosphorylation of HBx by Akt plays an important role. The current study provides an example of association of HBV genome variations with risks of HCC and chronic hepatitis.
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Affiliation(s)
- Wei-Ping Lee
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, National Yang-Ming University, Taiwan; Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.
| | - Keng-Hsin Lan
- Department of Pharmacology, National Yang-Ming University, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Chung-Pin Li
- School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Yee Chao
- School of Medicine, National Yang-Ming University, Taipei, Taiwan; Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Han-Chieh Lin
- School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Shou-Dong Lee
- School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
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Huang P, Zhuang B, Zhang H, Yan H, Xiao Z, Li W, Zhang J, Tang Q, Hu K, Koeffler HP, Wang J, Yin D. Hepatitis B Virus X Protein (HBx) Is Responsible for Resistance to Targeted Therapies in Hepatocellular Carcinoma: Ex Vivo Culture Evidence. Clin Cancer Res 2015; 21:4420-30. [PMID: 26059188 DOI: 10.1158/1078-0432.ccr-14-2067] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 05/19/2015] [Indexed: 11/16/2022]
Abstract
PURPOSE Molecular targeted therapy is an important approach for advanced hepatocellular carcinoma (HCC). Hepatitis B virus-related HCC (HBV-HCC) accounts for approximately 50% of all HCC cases. Bortezomib, a proteasome inhibitor (PI), is used extensively for the treatment of hematologic malignancies, but its application in HCC, particularly in HBV-HCC, has not been fully explored. EXPERIMENTAL DESIGN The effects of bortezomib on HCC tissues were evaluated by TUNEL assays. The growth inhibitory activity was measured using cell viability assays, and apoptosis was measured using flow cytometry. The levels of HBx, P-Raf/Raf, and P-Erk/Erk expression were measured by Western blot analysis. The ability of the MEK inhibitor PD98059 to enhance the cell killing activity of bortezomib was evaluated using ex vivo and in vivo methods. RESULTS The potency of bortezomib varied among HCC samples and cell lines, and HBV/HBx expression was associated with resistance to bortezomib. Bortezomib increased the levels of P-Raf and P-Erk in HBV/HBx-positive cells but not in HBV/HBx-negative HCC cells or in breast cancer or glioblastoma multiform cells. HBx was also upregulated after exposure to bortezomib, which was associated with the inhibition of proteasome activity. P-Erk upregulation mediated by bortezomib was effectively suppressed by the addition of the MEK inhibitor PD98059. Moreover, bortezomib and PD98059 synergistically inhibited HCC cell proliferation, as measured using both ex vivo and in vivo models. CONCLUSIONS Our studies demonstrate for the first time that HBx causes resistance to bortezomib in HCC, and this resistance can be antagonized by a MEK signaling inhibitor, providing a novel therapeutic approach.
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Affiliation(s)
- Pinbo Huang
- Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China. Guangdong Province Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Research Center of Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Baoxiong Zhuang
- Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China. Guangdong Province Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Research Center of Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Heyun Zhang
- Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China. Guangdong Province Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Research Center of Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Haiyan Yan
- Guangdong Province Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Research Center of Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Zhiyu Xiao
- Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Wenbin Li
- Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Jianlong Zhang
- Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Qibin Tang
- Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Kaishun Hu
- Guangdong Province Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Research Center of Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - H Phillip Koeffler
- Division of Hematology/Oncology, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California. National University of Singapore (CSI, NCIS), Singapore, Singapore
| | - Jie Wang
- Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China.
| | - Dong Yin
- Guangdong Province Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Research Center of Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China.
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Chen WN, Liu LL, Jiao BY, Lin WS, Lin XJ, Lin X. Hepatitis B virus X protein increases the IL-1β-induced NF-κB activation via interaction with evolutionarily conserved signaling intermediate in Toll pathways (ECSIT). Virus Res 2014; 195:236-45. [PMID: 25449573 DOI: 10.1016/j.virusres.2014.10.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 10/28/2014] [Accepted: 10/28/2014] [Indexed: 02/07/2023]
Abstract
Hepatitis B virus X protein (HBx) transactivates multiple transcription factors including nuclear factor-kappa B (NF-κB) that regulates inflammatory-related genes. However, the regulatory mechanism of HBx in NF-κB activation remains largely unknown. This study reports that HBx augments the interleukin-1β (IL-1β)-induced NF-κB activation via interaction with a Toll-like receptor (TLR) adapter protein, ECSIT (evolutionarily conserved signaling intermediate in Toll pathways). GST pull-down and co-immunoprecipitation analyses showed that HBx interacted with ECSIT. Deletion analysis of HBx in a CytoTrap two-hybrid system revealed that the interaction region of HBx for ECSIT was attributed to aa 51-80. Co-transfection of HBx and ECSIT in IL-1β-stimulated cells appeared to activate IKK and IκB signaling pathway as phosphorylation of both IKK α/β and IκBα was increased whereas knockdown of ECSIT or HBxΔ51-80 mutant attenuated the phosphorylation. As a consequence of IκBα degradation, NF-κB was activated as evidenced by increases in NF-κB transcriptional activity and the nuclear translocation of p65 and p50 that resulted in the induction of IL-10. In contrast, knockdown of ECSIT by siRNA or treatment with an NF-κB selective inhibitor (helenalin) abolished the NF-κB activation and IL-10 expression. We conclude that ECSIT appears to be a novel HBx-interacting signal molecule and their interaction is mechanistically important in IL-1β induction of NF-κB activation.
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Affiliation(s)
- Wan-nan Chen
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China; Key Laboratory of Tumor Microbiology, Department of Medical Microbiology, Fujian Medical University, Fuzhou, China
| | - Ling-ling Liu
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Bo-yan Jiao
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Wan-song Lin
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Xin-jian Lin
- Department of Medicine and UC San Diego Moores Cancer Center, University of California-San Diego, CA, USA.
| | - Xu Lin
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China; Key Laboratory of Tumor Microbiology, Department of Medical Microbiology, Fujian Medical University, Fuzhou, China.
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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 2014; 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] [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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Kuo CY, Chou TY, Chen CM, Tsai YF, Hwang GY, Hwang TL. Hepatitis B virus X protein disrupts stress fiber formation and triggers apoptosis. Virus Res 2013; 175:20-9. [PMID: 23591626 DOI: 10.1016/j.virusres.2013.03.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 03/22/2013] [Accepted: 03/26/2013] [Indexed: 12/28/2022]
Abstract
Cytoskeletal proteins are key participants in the cellular progression to apoptosis. In a previous study we injected nude mice with CCL13-HBx cells and identified in contrast to non-HBx transfected cells a differentially phosphorylated myosin light chain (p-MLC) by two-dimensional PAGE and mass spectrometry of the tumor material. To investigate the role of HBx in myosin light chain kinase (MLCK) signaling pathways, we analyzed the key molecules, p-MLC and MLCK, by western blotting. Immunofluorescence staining analysis showed that HBx disrupted stress fiber formation and that focal adhesion kinase (FAK) and integrin-linked kinase (ILK) were regulated by HBx-mediated phosphatase and tensin homolog (PTEN). We also used pharmacological inhibitors to explore the correlation between cytoskeletal rearrangements and HBx-mediated cell apoptosis via an MLCK and a PTEN-dependent pathway. The results showed that both ML9 and bvp restored the effects caused by HBx induction. Our findings suggest that HBx disrupts stress fiber formation and triggers apoptosis via an MLCK and a PTEN-dependent pathway.
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Affiliation(s)
- Chan-Yen Kuo
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan, Taiwan
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13
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Lim L, Tran BM, Vincan E, Locarnini S, Warner N. HBV-related hepatocellular carcinoma: the role of integration, viral proteins and miRNA. Future Virol 2012. [DOI: 10.2217/fvl.12.113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The development of hepatocellular carcinoma during chronic hepatitis B infection is a multifactorial process thought to be a consequence of several direct and indirect mechanisms. In this review we discuss how viral proteins and cycles of ongoing liver damage and regeneration, coupled with HBV DNA integration and aberrant miRNA expression may enhance the risk for the development of hepatocellular carcinoma.
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Affiliation(s)
- Lucy Lim
- Victorian Infectious Diseases Reference Laboratories, North Melbourne, Victoria, Australia
- Austin Liver Transplant Unit, Heidelberg, Victoria, Australia
| | - Bang Manh Tran
- Victorian Infectious Diseases Reference Laboratories, North Melbourne, Victoria, Australia
- Cancer Biology Laboratory, Department of Anatomy & Neuroscience, The University of Melbourne, Parkville, Victoria, Australia
| | - Elizabeth Vincan
- Victorian Infectious Diseases Reference Laboratories, North Melbourne, Victoria, Australia
- Cancer Biology Laboratory, Department of Anatomy & Neuroscience, The University of Melbourne, Parkville, Victoria, Australia
| | - Stephen Locarnini
- Victorian Infectious Diseases Reference Laboratories, North Melbourne, Victoria, Australia
| | - Nadia Warner
- Victorian Infectious Diseases Reference Laboratories, North Melbourne, Victoria, Australia
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14
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Rawat S, Clippinger AJ, Bouchard MJ. Modulation of apoptotic signaling by the hepatitis B virus X protein. Viruses 2012; 4:2945-72. [PMID: 23202511 PMCID: PMC3509679 DOI: 10.3390/v4112945] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 10/23/2012] [Accepted: 10/31/2012] [Indexed: 12/18/2022] Open
Abstract
Worldwide, an estimated 350 million people are chronically infected with the Hepatitis B Virus (HBV); chronic infection with HBV is associated with the development of severe liver diseases including hepatitis and cirrhosis. Individuals who are chronically infected with HBV also have a significantly higher risk of developing hepatocellular carcinoma (HCC) than uninfected individuals. The HBV X protein (HBx) is a key regulatory HBV protein that is important for HBV replication, and likely plays a cofactor role in the development of HCC in chronically HBV-infected individuals. Although some of the functions of HBx that may contribute to the development of HCC have been characterized, many HBx activities, and their putative roles during the development of HBV-associated HCC, remain incompletely understood. HBx is a multifunctional protein that localizes to the cytoplasm, nucleus, and mitochondria of HBV‑infected hepatocytes. HBx regulates numerous cellular signal transduction pathways and transcription factors as well as cell cycle progression and apoptosis. In this review, we will summarize reports in which the impact of HBx expression on cellular apoptotic pathways has been analyzed. Although various effects of HBx on apoptotic pathways have been observed in different model systems, studies of HBx activities in biologically relevant hepatocyte systems have begun to clarify apoptotic effects of HBx and suggest mechanisms that could link HBx modulation of apoptotic pathways to the development of HBV-associated HCC.
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Affiliation(s)
- Siddhartha Rawat
- Graduate Program in Molecular and Cellular Biology and Genetics, Drexel University College of Medicine, Philadelphia, PA 19102, USA;
| | - Amy J. Clippinger
- Department of Cancer Biology, Abramson Family Cancer Research Institute, School of Medicine, University of Pennsylvania Philadelphia, PA 19104, USA;
| | - Michael J. Bouchard
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
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15
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Pro-apoptotic or anti-apoptotic property of X protein of hepatitis B virus is determined by phosphorylation at Ser31 by Akt. Arch Biochem Biophys 2012; 528:156-62. [PMID: 22982405 DOI: 10.1016/j.abb.2012.08.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 08/14/2012] [Accepted: 08/16/2012] [Indexed: 01/16/2023]
Abstract
The X protein of hepatitis B virus (HBx) has been specifically implicated in either pro-apoptotic or anti-apoptotic activity in an experimental system, but the underlying mechanism is yet uncertain. Activations of survival and proliferation signaling pathways appear to account partly for its anti-apoptotic property. Change in mitochondrial membrane potential may be responsible for its apoptotic property. In this study, we isolated two HBx isoforms from an HBV carrier, one of which contains Akt phosphorylation site at Ser31 and functions as an anti-apoptotic protein (designated HBx-S31). The other does not contain Akt phosphorylation site and functions as an apoptotic protein (designated HBx-L31). HBx-S31 can activate Akt, whereas HBx-L31 cannot; the former enhances tumor growth, whereas the latter suppresses tumorigenesis. Our study provides evidence that HBx plays dual roles, namely pro-apoptotic and anti-apoptotic, through different isoforms in which HBx with Ser31 transduces survival signal.
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16
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Liu Y, Tong Z, Li T, Chen Q, Zhuo L, Li W, Wu RC, Yu C. Hepatitis B virus X protein stabilizes amplified in breast cancer 1 protein and cooperates with it to promote human hepatocellular carcinoma cell invasiveness. Hepatology 2012; 56:1015-24. [PMID: 22473901 DOI: 10.1002/hep.25751] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 03/23/2012] [Indexed: 12/12/2022]
Abstract
UNLABELLED Chronic infection of hepatitis B virus (HBV) is closely associated with the development of human hepatocellular carcinoma (HCC). HBV X protein (HBx) plays a key role in the progression of HCC. We recently found that amplified in breast cancer 1 (AIB1) protein is overexpressed in 68% of human HCC specimens and promotes HCC progression by enhancing cell proliferation and invasiveness. Given that both HBx and AIB1 play important oncogenic roles in HCC, we aimed to determine whether they could cooperatively promote human HCC development. Herein, we show that HBx-positive HCC tissues had a higher level of AIB1 protein, compared to HBx-negative HCC tissues. A positive correlation between HBx protein level and AIB1 protein level was established in HCC specimens. Without affecting its messenger RNA level, HBx induced a significant increase of the protein level of AIB1, which correlated with a significant extension of the half-life of AIB1 protein. Mechanistically, HBx could interact with AIB1 to prevent the interaction between envelope protein 3 ubiquitin ligase F-box and WD repeat domain containing 7 (Fbw7)α and AIB1, then inhibited the Fbw7α-mediated ubiquitination and degradation of AIB1. In addition, reporter assays and chromatin immunoprecipitation assays revealed that both HBx and AIB1 were recruited to matrix metalloproteinase-9 (MMP-9) promoter to enhance MMP-9 promoter activity cooperatively. Consistently, HBx and AIB1 cooperatively enhanced MMP-9 expression in HepG2 cells, which, in turn, increased cell-invasive ability. CONCLUSION Our study demonstrates that HBx can stabilize AIB1 protein and cooperate with it to promote human HCC cell invasiveness, highlighting the essential role of the cross-talk between HBx and AIB1 in HBV-related HCC progression.
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Affiliation(s)
- Yonghong Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China.
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Yuan K, Lian Z, Sun B, Clayton MM, Ng IOL, Feitelson MA. Role of miR-148a in hepatitis B associated hepatocellular carcinoma. PLoS One 2012; 7:e35331. [PMID: 22496917 PMCID: PMC3322146 DOI: 10.1371/journal.pone.0035331] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 03/13/2012] [Indexed: 12/26/2022] Open
Abstract
Hepatitis B virus encoded X antigen (HBx) is a trans-regulatory protein that alters the activity of selected transcription factors and cytoplasmic signal transduction pathways. HBx transcriptionally up-regulates the expression of a unique gene, URG11, which in turn transcriptionally up-regulates β-catenin, thereby contributing importantly to hepatocarcinogenesis. HBx and URG11 also alter the expression of multiple microRNAs, and by miRNA array analysis, both were shown to promote the expression of miR-148a. Elevated miR-148a was also seen in HBx positive liver samples from infected patients. To study the function of miR-148a, anti-148a was introduced into HepG2 and Hep3B cells stably expressing HBx or stably over-expressing URG11. Anti-miR-148a suppressed cell proliferation, cell cycle progression, cell migration, anchorage independent growth in soft agar and subcutaneous tumor formation in SCID mice. Introduction of anti-miR-148a increased PTEN protein and mRNA expression, suggesting that PTEN was targeted by miR-148a. Anti-miR-148a failed to suppress PTEN expression when co-transfected with reporter gene mutants in the 3′UTR of PTEN mRNA. Introduction of anti-miR-148a also resulted in depressed Akt signaling by HBx and URG11, resulting in decreased expression of β-catenin. Thus, miR-148a may play a central role in HBx/URG11 mediated HCC, and may be an early diagnostic marker and/or therapeutic target associated with this tumor type.
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Affiliation(s)
- Ke Yuan
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Zhaorui Lian
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Bill Sun
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Marcia M. Clayton
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Irene O. L. Ng
- Department of Pathology, University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong
| | - Mark A. Feitelson
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
- Center for Biotechnology, Sbarro Health Research Organization, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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18
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Cho IR, Oh M, Koh SS, Malilas W, Srisuttee R, Jhun BH, Pellegrini S, Fuchs SY, Chung YH. Hepatitis B virus X protein inhibits extracellular IFN-α-mediated signal transduction by downregulation of type I IFN receptor. Int J Mol Med 2012; 29:581-6. [PMID: 22218495 PMCID: PMC3577137 DOI: 10.3892/ijmm.2012.879] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Accepted: 11/23/2011] [Indexed: 12/15/2022] Open
Abstract
We have previously shown that hepatitis B virus (HBV) protein X (HBX), a regulatory protein of HBV, activates Stat1, leading to type I interferon (IFN) production. Type I IFN secreted from HBX-expressing hepatic cells enforces antiviral signals through its binding to the cognate type I IFN receptor. We therefore investigated how cells handle this detrimental situation. Interestingly, compared to Chang cells stably expressing an empty vector (Chang-Vec), Chang cells stably expressing HBX (Chang-HBX) showed lower levels of IFN-α receptor 1 (IFNAR1) protein, a subunit of type I IFN receptor. The levels of IFNAR1 transcripts detected in Chang-HBX cells were lower than the levels in Chang-Vec cells, indicating that HBX regulates IFNAR1 at the transcriptional level. Moreover, we observed that HBX induced the translocation of IFNAR1 to the cytoplasm. Consistent with these observations, HBX also downregulated Tyk2, which is required for the stable expression of IFNAR1 on the cell surface. Eventually, Chang-HBX cells consistently maintained a lower level of IFNAR1 expression and displayed no proper response to IFN-α, while Chang-Vec cells exhibited a proper response to IFN-α treatment. Taken together, we propose that HBX downregulates IFNAR1, leading to the avoidance of extracellular IFN-α signal transduction.
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Affiliation(s)
- Il-Rae Cho
- WCU Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 609-735, Republic of Korea
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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; 7:1149-67. [DOI: 10.2217/fon.11.95] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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20
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Jiao BY, Lin WS, She FF, Chen WN, Lin X. Hepatitis B virus X protein enhances activation of nuclear factor κB through interaction with valosin-containing protein. Arch Virol 2011; 156:2015-21. [PMID: 21918864 DOI: 10.1007/s00705-011-1099-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 08/29/2011] [Indexed: 12/26/2022]
Abstract
Hepatitis B virus X protein (HBx protein) is a multifunctional regulatory protein. The transactivation of nuclear factor kappa B (NF-κB) by HBx protein has been shown to be of importance in the pathogenesis of HBV-related diseases. However, the mechanism involved remains largely unclear. In this study, a CytoTrap yeast two-hybrid system was employed to screen binding partners of the HBx protein; 29 cellular proteins, including valosin-containing protein (VCP), were identified. The interaction between HBx protein and VCP was further confirmed in vitro and in vivo using a glutathione S-transferase pull-down assay and co-immunoprecipitation, respectively. It was also shown that this interaction is mediated by amino acid residues 51-120 of the HBx protein. In Huh-7 hepatoma cells, HBx protein enhanced the VCP-mediated activation of NF-κB. Our findings provide new insights into the molecular mechanisms that lead to the activation of NF-κB by HBx protein.
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Affiliation(s)
- Bo-Yan Jiao
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Research Center of Molecular Medicine, Fujian Medical University, 88 Jiaotong Road, Fuzhou 350004, People's Republic of China
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21
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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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22
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Ha HL, Yu DY. HBx-induced reactive oxygen species activates hepatocellular carcinogenesis via dysregulation of PTEN/Akt pathway. World J Gastroenterol 2010; 16:4932-7. [PMID: 20954279 PMCID: PMC2957601 DOI: 10.3748/wjg.v16.i39.4932] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [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 investigate the role of hepatitis B virus X-protein (HBx)-induced reactive oxygen species (ROS) on liver carcinogenesis in HBx transgenic mice and HepG2-HBx cells.
METHODS: Cell growth rate was analyzed, and through western blotting, mitogenic signaling was observed. Endogenous ROS from wild and HBx transgenic mice and HepG2-Mock and HBx cells were assayed by FACScalibur. Identification of oxidized and reduced phosphatase and tensin homolog (PTEN) was analyzed through N-ethylmaleimide alkylation, nonreducing electrophoresis.
RESULTS: We observed that the cell-proliferation-related phosphoinositide 3-kinase/Akt pathway is activated by HBx in vivo and in vitro. Increased ROS were detected by HBx. Tumor suppressor PTEN, via dephosphorylation of Akt, was oxidized and inactivated by increased ROS. Increased oxidized PTEN activated the mitogenic pathway through over-activated Akt. However, treatment with ROS scavenger N-acetyl cysteine can reverse PTEN to a reduced form. Endogenously produced ROS also stimulated HBx expression.
CONCLUSION: HBx induced ROS promoted Akt pathways via oxidized inactive PTEN. HBx and ROS maintained a positive regulatory loop, which aggravated carcinogenesis.
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23
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Lizzano RA, Yang B, Clippinger AJ, Bouchard MJ. The C-terminal region of the hepatitis B virus X protein is essential for its stability and function. Virus Res 2010; 155:231-9. [PMID: 20969903 DOI: 10.1016/j.virusres.2010.10.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 10/10/2010] [Accepted: 10/12/2010] [Indexed: 02/06/2023]
Abstract
More than 350 million people worldwide are chronically infected with the human hepatitis B virus (HBV). Chronic HBV infections are associated with the development of hepatocellular carcinoma. While the mechanism of HBV-associated carcinoma remains undefined, it is thought to involve a combination of a continuous inflammatory response to HBV-infected hepatocytes and activities of HBV proteins such as the HBV X protein (HBx). HBx stimulates HBV replication; however, the mechanism by which HBx stimulates HBV replication remains incompletely understood. Studies performed with the woodchuck hepatitis virus (WHV) in woodchucks demonstrated that a C-terminally truncated mutant of the WHV X protein could not stimulate WHV replication. However, whether the C-terminus of HBx is important for HBx-stimulation of HBV replication is unclear. We have constructed C-terminal truncation mutants of HBx and have demonstrated that the C-terminus of HBx impacts HBx stability, HBx activation of transcription, and HBx stimulation of HBV replication. These observations highlight the impact of the HBx C-terminus on HBx activities and the importance of directly analyzing HBx expression and functions in HBV-associated tumors that contain chromosomal integrants of HBV with truncations of the HBx gene.
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Affiliation(s)
- Rebecca A Lizzano
- Graduate Program in Molecular and Cellular Biology and Genetics, Drexel University College of Medicine, Philadelphia, PA 19102, United States
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24
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Kim KH. [Pro-apoptotic function of hepatitis B virus X protein]. THE KOREAN JOURNAL OF HEPATOLOGY 2010; 16:112-22. [PMID: 20606495 DOI: 10.3350/kjhep.2010.16.2.112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Infection of hepatitis B virus (HBV) is a main cause of liver diseases including hepatitis, cirrhosis and hepatocellular carcinoma (HCC). Among the HBV-encoded proteins, the HBV X protein (HBx) has been suspected to be strongly involved in HBV-associated liver pathogenesis. HBx, a virally encoded multifunctional regulator, has been shown to induce apoptosis, anti-apoptosis, proliferation, and transformation of cells depending on the cell lines, model systems used, assay protocols, and research groups. Among the several activities of HBx, the pro-apoptotic function of HBx will be discussed in this review. Given that the disruption of apoptosis pathway by HBx contributes to the liver pathogenesis, a better understanding of the molecular interference in the cellular pro-apoptotic networks by HBx will provide useful clues for the intervention in HBV-mediated liver diseases.
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Affiliation(s)
- Kyun-Hwan Kim
- Department of Pharmacology, School of Medicine and Center for Cancer Research and Diagnostic Medicine, IBST, Konkuk University, Seoul, Korea.
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25
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Ierardi E, Rosania R, Zotti M, Giorgio F, Prencipe S, Valle ND, Francesco VD, Panella C. From chronic liver disorders to hepatocellular carcinoma: Molecular and genetic pathways. World J Gastrointest Oncol 2010; 2:259-64. [PMID: 21160638 PMCID: PMC2998843 DOI: 10.4251/wjgo.v2.i6.259] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 11/24/2009] [Accepted: 12/01/2009] [Indexed: 02/05/2023] Open
Abstract
Hepatocarcinogenesis is a process attributed to progressive genomic changes that alter the hepatocellular phenotype producing cellular intermediates that evolve into hepatocellular carcinoma (HCC). During the preneoplastic phase, the liver is often the site of chronic hepatitis and/or cirrhosis, and these conditions induce liver regeneration with accelerated hepatocyte cycling in an organ that is otherwise proliferatively at rest. Hepatocyte regeneration is accelerated by upregulation of mitogenic pathways involving molecular and genetic mechanisms. Hepatic growth factors, inhibitors and triggers may also play a role. This process leads to the production of monoclonal populations of aberrant and dysplastic hepatocytes that have telomerase re-expression, microsatellite instability, and occasionally structural aberrations in genes and chromosomes. Development of dysplastic hepatocytes in foci and nodules and the emergence of HCC are associated with the accumulation of irreversible structural alterations in genes and chromosomes even if the genomic basis of the malignant phenotype is largely heterogeneous. Therefore, a malignant hepatocyte phenotype may be produced by changes in genes acting through different regulatory pathways, thus producing several molecular variants of HCC. On these bases, a key point for future research will be to determine whether the deletions are specific, due to particular loci in the minimally deleted regions of affected chromosome arms, or whether they are non-specific with loss of large portions of chromosomes or entire chromosome arms leading to passive deletion of loci. The final aim is the possibility of identifying a step where carcinogenetic processes could be terminated.
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Affiliation(s)
- Enzo Ierardi
- Enzo Ierardi, Rosa Rosania, Mariangela Zotti, Floriana Giorgio, Simonetta Prencipe, Nicola Della Valle, Vincenzo De Francesco, Carmine Panella, Section of Gastroenterology, Department of Medical Sciences, University of Foggia, Ospedali Riuniti, Viale L. Pinto 71100-Foggia, Italy
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26
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Abstract
NF-kappaB (nuclear factor kappaB) is a heterodimeric transcription factor that is constitutively expressed in all cell types and has a central role as a transcriptional regulator in response to cellular stress. In the present review, we discuss the role of NF-kappaB signalling in the maintenance of liver homoeostasis as well as in the pathogenesis of a wide variety of conditions affecting the liver, including viral hepatitis, steatohepatitis, cirrhosis and hepatocellular carcinoma. Much of the current knowledge of NF-kappaB signalling in the liver relates to the canonical pathway, the IKK [IkappaB (inhibitor of kappaB) kinase] complex and the RelA subunit. We explore the weaknesses of the experimental approaches to date and suggest that further work is needed to investigate in detail the discreet functions of each of the Rel subunits in liver physiology and disease.
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27
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Bui-Nguyen TM, Pakala SB, Sirigiri RD, Xia W, Hung MC, Sarin SK, Kumar V, Slagle BL, Kumar R. NF-kappaB signaling mediates the induction of MTA1 by hepatitis B virus transactivator protein HBx. Oncogene 2010; 29:1179-89. [PMID: 20010875 PMCID: PMC3621706 DOI: 10.1038/onc.2009.404] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 07/22/2009] [Accepted: 09/09/2009] [Indexed: 12/12/2022]
Abstract
Metastasis-associated protein 1 (MTA1), a master chromatin modifier, has been shown to regulate cancer progression and is widely upregulated in human cancer, including hepatitis B virus-associated hepatocellular carcinomas (HCCs). Here we provide evidence that hepatitis B virus transactivator protein HBx stimulates the expression of MTA1 but not of MTA2 or MTA3. The underlying mechanism of HBx stimulation of MTA1 involves HBx targeting of transcription factor nuclear factor (NF)-kappaB and the recruitment of HBx/p65 complex to the NF-kappaB consensus motif on the relaxed MTA1 gene chromatin. We also discovered that MTA1 depletion in HBx-expressing cells severely impairs the ability of HBx to stimulate NF-kappaB signaling and the expression of target proinflammatory molecules. Furthermore, the presence of HBx in HBx-infected HCCs correlated well with increased MTA1 and NF-kappaB-p65. Collectively, these findings revealed a previously unrecognized integral role of MTA1 in HBx stimulation of NF-kappaB signaling and consequently, the expression of NF-kappaB targets gene products with functions in inflammation and tumorigenesis.
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Affiliation(s)
- Tri M. Bui-Nguyen
- Department of Biochemistry and Molecular Biology and Institute of Coregulator Biology, The George Washington University, Washington, District of Columbia, USA
| | - Suresh B. Pakala
- Department of Biochemistry and Molecular Biology and Institute of Coregulator Biology, The George Washington University, Washington, District of Columbia, USA
| | - Reddy Divijendranatha Sirigiri
- Department of Biochemistry and Molecular Biology and Institute of Coregulator Biology, The George Washington University, Washington, District of Columbia, USA
| | - Weiya Xia
- Department of Molecular and Cellular Oncology, MD Anderson Cancer Center, Houston, Texas, USA
| | - Mien-Chie Hung
- Department of Molecular and Cellular Oncology, MD Anderson Cancer Center, Houston, Texas, USA
- Center for Molecular Medicine, Graduate Institute of Cancer Biology, China Medical University and Hospital, Taichung, Taiwan
| | - Shiv Kumar Sarin
- Department of Gastroenterology, G.P. Pant Hospital, Institute of Liver and Biliary Sciences, New Delhi, India
- Department of Hepatology, Institute of Liver and Biliary Sciences, New Delhi, India
| | - Vijay Kumar
- Virology Laboratory, International Centre for Genetic Engineering & Biotechnology, New Delhi, India
| | - Betty L. Slagle
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Rakesh Kumar
- Department of Biochemistry and Molecular Biology and Institute of Coregulator Biology, The George Washington University, Washington, District of Columbia, USA
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28
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29
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Lee YM, Kang M, Hwang JM, Lee S, Cho H, Kim YS. Sulfasalazine induces apoptosis of HBx-expressing cells in an NF-kappaB-independent manner. Virus Genes 2009; 40:37-43. [PMID: 19859796 DOI: 10.1007/s11262-009-0416-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Accepted: 10/15/2009] [Indexed: 01/17/2023]
Abstract
The Hepatitis B virus (HBV) is a causative agent of acute chronic hepatitis, cirrhosis, and hepatocarcinoma. The Hepatitis B virus X protein (HBx) has pleiotypic functions in the regulation of proliferation and apoptosis. It has been suggested that the anti-inflammatory drug sulfasalazine, which is commonly used to treat rheumatoid arthritis and inflammatory bowel disease, inhibits nuclear factor NF-kappaB and induces cell death in HBx-expressing liver cells. In this study, we demonstrate that sulfasalazine induces cell death via apoptosis in HBx-expressing liver cells, as evidenced by characteristic changes in nuclear morphology, cleavage of poly (ADP-ribose) polymerase (PARP), caspase-3 and caspase-9, and activation of caspase-3. We also demonstrate that inhibition of NF-kappaB by siRNA fails to induce apoptosis of HBx-expressing liver cells, indicating that sulfasalazine modulates apoptosis of HBx-expressing cells in an NF-kappaB-independent manner.
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Affiliation(s)
- Young-Man Lee
- Indang Institute of Molecular Biology, Inje University, Jeodong 2-Ga 64, Chung-Ku, Seoul, 100-032, Republic of Korea
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30
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Hepatitis B virus X protein modulates apoptosis in primary rat hepatocytes by regulating both NF-kappaB and the mitochondrial permeability transition pore. J Virol 2009; 83:4718-31. [PMID: 19279112 DOI: 10.1128/jvi.02590-08] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The hepatitis B virus (HBV) X protein (HBx) is a multifunctional protein that regulates numerous cellular signal transduction pathways, including those that modulate apoptosis. However, different HBx-dependent effects on apoptosis have been reported; these differences are likely the consequence of the exact conditions and cell types used in a study. Many of the previously reported studies that analyzed HBx regulation of apoptosis were conducted in immortalized or transformed cells, and the alterations that have transformed or immortalized these cells likely impact apoptotic pathways. We examined the effects of HBx on apoptotic pathways in cultured primary rat hepatocytes, a biologically relevant system that mimics normal hepatocytes in the liver. We analyzed the effects of HBx on apoptosis both when HBx was expressed in the absence of other HBV proteins and in the context of HBV replication. HBx stimulation of NF-kappaB inhibited the activation of apoptotic pathways in cultured primary rat hepatocytes. However, when HBx-induced activation of NF-kappaB was blocked, HBx stimulated apoptosis; blocking the activity of the mitochondrial permeability transition pore inhibited HBx activation of apoptosis. These results suggest that HBx can be either proapoptotic or antiapoptotic in hepatocytes, depending on the status of NF-kappaB, and confirm previous studies that link some HBx activities to modulation of the mitochondrial permeability transition pore. Overall, our studies define apoptotic pathways that are regulated by HBx in cultured primary hepatocytes and provide potential mechanisms for the development of HBV-associated liver cancer.
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Cha MY, Ryu DK, Jung HS, Chang HE, Ryu WS. Stimulation of hepatitis B virus genome replication by HBx is linked to both nuclear and cytoplasmic HBx expression. J Gen Virol 2009; 90:978-986. [PMID: 19264639 DOI: 10.1099/vir.0.009928-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
HBx, a small regulatory protein of hepatitis B virus, plays an important role in stimulating viral genome replication. HBx was shown to be associated with diverse subcellular locations, such as the nucleus, cytoplasm and mitochondria. Some studies have linked the stimulation of genome replication by HBx to its cytoplasmic function, while other reports have attributed this function to its nuclear component. To clarify this discrepancy, we measured viral genome replication by complementing an HBx-null replicon in two different ways: by (i) co-transfecting with an increasing amount of HBx expression plasmid and (ii) co-transfecting with re-targeted variants of HBx that are confined to either the nucleus or the cytoplasm due to either the nuclear localization signal (NLS) or the nuclear export signal (NES) tags, respectively. Intriguingly, immunostaining analysis indicated that the subcellular localization of HBx is primarily influenced by its abundance; HBx is confined to the nucleus at low levels but is usually detected in the cytoplasm at high levels. Importantly, HBx, whether re-targeted by either the NLS or NES tag, stimulates viral genome replication to a level comparable to that of the wild-type. Furthermore, similar to the wild-type, the stimulation of viral genome replication by the re-targeted HBx occurred at the transcription level. Thus, we concluded that the stimulation of viral genome replication by HBx is linked to both nuclear and cytoplasmic HBx, although the underlying mechanism of stimulation most likely differs.
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Affiliation(s)
- Man-Young Cha
- Department of Biochemistry, Yonsei University, Seoul 120-749, Republic of Korea
| | - Dong-Kyun Ryu
- Department of Biochemistry, Yonsei University, Seoul 120-749, Republic of Korea
| | - Hyeon-Sik Jung
- Department of Biochemistry, Yonsei University, Seoul 120-749, Republic of Korea
| | - Ho-Eun Chang
- Department of Biochemistry, Yonsei University, Seoul 120-749, Republic of Korea
| | - Wang-Shick Ryu
- Department of Biochemistry, Yonsei University, Seoul 120-749, Republic of Korea
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Park EH, Koh SS, Srisuttee R, Cho IR, Min HJ, Jhun BH, Lee YS, Jang KL, Kim CH, Johnston RN, Chung YH. Expression of HBX, an oncoprotein of hepatitis B virus, blocks reoviral oncolysis of hepatocellular carcinoma cells. Cancer Gene Ther 2008; 16:453-61. [PMID: 19096445 DOI: 10.1038/cgt.2008.95] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Although reovirus has been used in tests as a potential cancer therapeutic agent against a variety of cancer cells, its application to hepatocellular carcinoma cells, in which the hepatitis B virus (HBV) X (HBX) protein of HBV plays a primary role, has not yet been explored. Here, we describe experiments in which we use reovirus to treat Chang liver carcinoma cells expressing either a vector only (Chang-vec) or a vector encoding HBX protein (Chang-HBX). Although Chang-vec cells readily support reoviral proliferation and undergo apoptosis, Chang-HBX cells are highly resistant to reoviral infection and virus-induced apoptosis, even though HBX protein induces activation of Ras and inactivation of PKR, which are normally thought to enhance reoviral oncolysis. The resistance of Chang-HBX cells to reovirus may instead be explained by HBX-induced downregulation of death receptor 5 and activation of Stat1. Phosphorylated Stat1 activates interferon (IFN)-stimulated regulatory element (ISRE)- and IFN-gamma-activated sequence (GAS)-mediated transcription, leading to the production of IFN-beta, whereas the reduced expression of Stat1 with its siRNA results in a decrease in IFN-beta production, by which Chang-HBX cells eventually succumb to reovirus infection. This result further indicates that HBX induces the establishment of an antiviral state through Stat1 activation. Thus, it appears that active Ras does not override the antiviral effect mediated by the activation of Stat1. Accordingly, we report that HBX, an oncoprotein of HBV, can prevent reoviral oncolysis of hepatocellular carcinoma. This suggests there may be limits to the practical application of reovirus in the treatment of human cancers already expressing other oncoviral proteins.
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Affiliation(s)
- E-H Park
- Department of Nanomedical Engineering, BK21 Nanofusion Technology Team, Pusan National University, Miryang, Republic of Korea
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Clippinger AJ, Bouchard MJ. Hepatitis B virus HBx protein localizes to mitochondria in primary rat hepatocytes and modulates mitochondrial membrane potential. J Virol 2008; 82:6798-811. [PMID: 18448529 PMCID: PMC2446973 DOI: 10.1128/jvi.00154-08] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 04/22/2008] [Indexed: 12/20/2022] Open
Abstract
Over 350 million people are chronically infected with hepatitis B virus (HBV), and a significant number of chronically infected individuals develop primary liver cancer. HBV encodes seven viral proteins, including the nonstructural X (HBx) protein. The results of studies with immortalized or transformed cells and with HBx-transgenic mice demonstrated that HBx can interact with mitochondria. However, no studies with normal hepatocytes have characterized the precise mitochondrial localization of HBx or the effect of HBx on mitochondrial physiology. We have used cultured primary rat hepatocytes as a model system to characterize the mitochondrial localization of HBx and the effect of HBx expression on mitochondrial physiology. We now show that a fraction of HBx colocalizes with density-gradient-purified mitochondria and associates with the outer mitochondrial membrane. We also demonstrate that HBx regulates mitochondrial membrane potential in hepatocytes and that this function of HBx varies depending on the status of NF-kappaB activity. In primary rat hepatocytes, HBx activation of NF-kappaB prevented mitochondrial membrane depolarization; however, when NF-kappaB activity was inhibited, HBx induced membrane depolarization through modulation of the mitochondrial permeability transition pore. Collectively, these results define potential pathways through which HBx may act in order to modulate mitochondrial physiology, thereby altering many cellular activities and ultimately contributing to the development of HBV-associated liver cancer.
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Affiliation(s)
- Amy J Clippinger
- Graduate Program in Molecular and Cellular Biology and Genetics, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, USA
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Ye L, Dong N, Wang Q, Xu Z, Cai N, Wang H, Zhang X. Progressive changes in hepatoma cells stably transfected with hepatitis B virus X gene. Intervirology 2008; 51:50-8. [PMID: 18334850 DOI: 10.1159/000120289] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Accepted: 12/20/2007] [Indexed: 12/27/2022] Open
Abstract
OBJECTIVE The aim of this study is to investigate the molecular mechanism of hepatocellular carcinoma (HCC) development induced by hepatitis B virus X protein (HBx). METHODS We previously established a H7402-X cell line that constitutively expresses HBx protein. In the present study, H7402-X gene expression profiles and proteins were examined using cDNA microarrays and Western blot analysis. Apoptosis was induced by adriamycin in H7402-X cells. The transcriptional activities of NF-kappaB and AP-1 were examined using a luciferase reporter gene. RESULTS The DNA expression profiles identified candidate genes showing aberrant expression in cells overexpressing HBx. Western blot analysis showed that cyclin D, cyclin E, survivin, Bcl-2, and PCNA were up-regulated, whereas p27 was down-regulated in H7402-X cells. Treatment with RNAi targeting HBx mRNA led to the down-regulation of these genes. H7402-X cells were resistant to adriamycin-induced apoptosis. Luciferase reporter gene analysis revealed that HBx induces the transcriptional activities of NF-kappaB and AP-1. CONCLUSION Our data provide additional insight into cellular targets of HBx, which allows a better understanding of HBx function and the progressive changes during HBx-mediated hepatocarcinogenesis.
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Affiliation(s)
- Lihong Ye
- Department of Biochemistry, College of Life Sciences, Nankai University, Tianjin, PR China
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36
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Kuo CY, Wang JC, Wu CC, Hsu SL, Hwang GY. Effects of hepatitis B virus X protein (HBx) on cell-growth inhibition in a CCL13-HBx stable cell line. Intervirology 2008; 51:26-32. [PMID: 18309246 DOI: 10.1159/000118793] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Accepted: 01/03/2008] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVE The known function of hepatitis B virus X protein (HBx) is to determine the fate of cells by modulating various signaling pathways. In our previous study, we demonstrated that HBx inhibits tumor formation in nude mice injected with CCL13-HBx stable cell lines; however, the mechanism underlying this inhibition is unclear. METHODS To investigate the possible mechanisms underlying HBx involvement in CCL13-HBx cells, gene profiles were initially analyzed by DNA microarray technology and subsequently confirmed by performing semiquantitative RT-PCR and Western blotting. Furthermore, the phenomenon of cell death via apoptosis was detected via DNA fragmentation, TUNEL staining, caspase-3 activity assay, and propidium iodide (PI) staining. RESULTS The results indicated that HBx induction downregulated Wnt-3 and beta-catenin that are involved in cell proliferation. Moreover, HBx induction repressed cell growth and downregulated the expressions of cyclin D1, CDK4, cyclin E, CDK2, and cyclin B1. Furthermore, HBx induction triggered cell death via apoptosis, as determined by DNA fragmentation, TUNEL staining, caspase-3 activity assay, and PI staining. CONCLUSION Most importantly, our results indicated that HBx induction in the CCL13-HBx stable cell line downregulated Wnt-3/beta-catenin expression and suppressed cell growth by repressing cell proliferation or triggering cell apoptosis.
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Affiliation(s)
- Chan-Yen Kuo
- Department of Life Science, Tunghai University, Taichung, Taiwan
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Pang RWC, Joh JW, Johnson PJ, Monden M, Pawlik TM, Poon RTP. Biology of Hepatocellular Carcinoma. Ann Surg Oncol 2008; 15:962-71. [PMID: 18236113 DOI: 10.1245/s10434-007-9730-z] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 09/19/2007] [Accepted: 09/19/2007] [Indexed: 12/11/2022]
Affiliation(s)
- Roberta W C Pang
- Centre for Cancer Research, The University of Hong Kong, 102 Pokfulam Road, Hong Kong, China
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38
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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: 150] [Impact Index Per Article: 8.8] [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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Su JM, Lai XM, Lan KH, Li CP, Chao Y, Yen SH, Chang FY, Lee SD, Lee WP. X protein of hepatitis B virus functions as a transcriptional corepressor on the human telomerase promoter. Hepatology 2007; 46:402-13. [PMID: 17559154 DOI: 10.1002/hep.21675] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
UNLABELLED The X protein of hepatitis B virus (HBx) is essential for transactivation of hepatitis B viral and host cellular genes. It has been specifically implicated in the development of hepatocellular carcinoma; however, the molecular mechanism remains unknown. Telomeres, the DNA-protein complexes at the ends of eukaryotic chromosomes, protect chromosomes from degradation at the terminal regions, fusion with a broken DNA end, and inappropriate recombination. The shortening of telomeres that occurs during hepatocellular carcinogenesis has been well studied. In the present study, we isolated an HBx isoform that resulted in telomere shortening in hepatoma cell lines. We found that this HBx isoform down-regulated the expression of human telomerase by transcriptionally repressing its promoter. To further determine the molecular mechanism, we examined human telomerase promoter and identified myc-associated zinc finger protein (MAZ) as a transcriptional repressor of the promoter. We found that the HBx isoform achieved transcriptional suppression of human telomerase by enhancing MAZ binding to its consensus sequence in the promoter through physical association with MAZ. CONCLUSION The data suggest that HBx can induce telomere shortening by acting as a transcriptional corepressor of MAZ on the human telomerase promoter.
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Affiliation(s)
- Jiun-Ming Su
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, National Yang-Ming 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: 98] [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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Um HR, Lim WC, Chae SY, Park S, Park JH, Cho H. Raf-1 and protein kinase B regulate cell survival through the activation of NF-kappaB in hepatitis B virus X-expressing cells. Virus Res 2006; 125:1-8. [PMID: 17188775 DOI: 10.1016/j.virusres.2006.11.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2006] [Revised: 11/10/2006] [Accepted: 11/10/2006] [Indexed: 12/17/2022]
Abstract
We previously demonstrated that activation of NF-kappaB by the hepatitis B virus X (HBx) gene plays an important role in cell survival. In the present study, we explored the upstream mediators of NF-kappaB activation and their correlations with cell survival. XTT assays and colony generation assays revealed that inhibition of NF-kappaB activation indeed increased cell death in HBx-expressing cells. Utilizing inactivating mutants of signal transducers, we showed that dominant negative mutants of stress-activated protein kinase/extracellular signal-regulated kinase (SEK1) or PKCalpha significantly diminished the HBx-mediated NF-kappaB activation. However, neither of these mutants significantly affected the cell survival in colony generation assays. In contrast, inactivating mutants of Raf-1 or PKB (protein kinase B)/Akt abrogated the HBx-mediated NF-kappaB activation and also suppressed the cell survival. Our results suggest that the Raf-1 or PKB-mediated NF-kappaB activation promotes cell survival in HBx-expressing cells.
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Affiliation(s)
- Hae-Ryun Um
- Department of Biochemistry and Molecular Biology, Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, 5 Wonchon-Dong, Yeongtong-Gu, Suwon, Republic of Korea
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Zhang X, Zhang H, Ye L. Effects of hepatitis B virus X protein on the development of liver cancer. ACTA ACUST UNITED AC 2006; 147:58-66. [PMID: 16459163 DOI: 10.1016/j.lab.2005.10.003] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 10/08/2005] [Accepted: 10/20/2005] [Indexed: 02/08/2023]
Abstract
Hepatitis B virus (HBV) infections play an important role in the development of cirrhosis and hepatocellular carcinoma (HCC). The pathogenesis of HBV-related HCC, however, has not been fully described. Evidence suggests that the HBV X protein (HBx) plays a crucial role in the pathogenesis of HCC. The high occurrence of anti-HBx antibody in the serum of HCC patients indicates that it could be a prognostic marker of HBV infection and HCC. HBx stimulates and influences signal transduction pathways within cells. HBx also binds to such protein targets as p53, proteasome subunits, and UV-damaged DNA binding proteins. It also interacts with the cyclic AMP-responsive element binding protein, ATF-2, NFkappaB, and basal transcription factors. HBx is primarily localized to the cytoplasm, where it interacts with and stimulates protein kinases, including protein kinase C, Janus kinase/STAT, IKK, PI-3-K, stress-activated protein kinase/Jun N-terminal kinase, and protein kinase B/Akt. It is also found in the mitochondrion, where it influences the Bcl-2 family. This review examines the role of HBx in the life cycle of HBV as well as the various signal transduction pathways involved in the pathogenesis of HBV-induced hepatocarcinogenesis.
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Affiliation(s)
- Xiaodong Zhang
- Department of Cancer Research, Institute for Molecular Biology, Nankai University, Tianjin, P. R. China.
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43
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Wang XZ, Li D, Tao QM, Lin N, Chen ZX. A novel hepatitis B virus X-interactive protein: cytochrome C oxidase III. J Gastroenterol Hepatol 2006; 21:711-5. [PMID: 16677157 DOI: 10.1111/j.1440-1746.2006.04139.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND Hepatitis B virus-encoded X protein has been shown to be capable of activating many different viral and cellular promoters through protein-protein interactions and to contribute to the development of hepatocellular carcinoma. As its mechanism has not yet been identified unequivocally, the aim of the present study was to screen the cellular proteins that can interact with X protein. METHODS The yeast two-hybrid system was used to screen the X-interactive protein. False positive clones were eliminated by segregation analysis, and then putative positive clones were amplified, sequenced and analyzed with bioinformatics. A mating experiment was performed to confirm the binding of putative proteins to X protein in the yeast cells. The specific interaction between X protein and putative proteins in mammalian cells was verified by coimmunoprecipitation. RESULTS The hepatitis B virus X-interactive protein recovered from a human liver cDNA library was cytochrome C oxidase III. The specific interaction between protein X and cytochrome C oxidase III was verified by mating experiment and coimmunoprecipitation of COS7 cell lysates expressing both proteins. CONCLUSION These data support the speculation that cytochrome C oxidase III is a novel functional target of hepatitis B virus X protein in cells.
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Affiliation(s)
- Xiao Zhong Wang
- Department of Gastroenterology, Union Hospital of Fujian Medical University, Fuzhou, Fujian Province, China.
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44
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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: 3.6] [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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45
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Arsura M, Cavin LG. Nuclear factor-kappaB and liver carcinogenesis. Cancer Lett 2005; 229:157-69. [PMID: 16125305 DOI: 10.1016/j.canlet.2005.07.008] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Accepted: 07/10/2005] [Indexed: 02/06/2023]
Abstract
Hepatocellular carcinoma (HCC) is the third deadliest and fifth most common human cancer worldwide. Hepatitis C virus (HCV) and hepatitis B virus (HBV) infections along with alcohol and aflatoxin B1 intake are widely recognized etiological agents in HCCs. It is anticipated that HCCs will constitute a major health problem in the next two decades because of the rising incidence of HCV infections in the US. The poor survival rate achieved by current surgical procedures and chemotherapy treatment has prompted the scientific community to gain a better understanding of the molecular events involved in hepatocarcinogenesis in order to define new targets for more effective treatment. Recent findings from several laboratories have implicated constitutive activation of the transcription factor NF-kappaB as one of the early key events involved in neoplastic progression of the liver. Data is summarized here from recently published studies illustrating a crucial role of NF-kappaB in bridging the action of growth factors and inflammation to hepatic oncogenesis. Although additional work is needed to fully understand the precise role of NF-kappaB in the regulation of the various transitions of HCC development, these new findings raise the intriguing possibility that pharmacologic inhibition of NF-kappaB in the liver could selectively eradicate malignant liver cells without affecting normal liver homeostasis.
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Affiliation(s)
- Marcello Arsura
- Department of Pharmacology, College of Medicine, University of Tennessee Cancer Institute, University of Tennessee Health Science Center, 874 Union Avenue, Memphis, TN 38163, USA.
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Nakanishi F, Ohkawa K, Ishida H, Hosui A, Sato A, Hiramatsu N, Ueda K, Takehara T, Kasahara A, Sasaki Y, Hori M, Hayashi N. Alteration in gene expression profile by full-length hepatitis B virus genome. Intervirology 2005; 48:77-83. [PMID: 15812178 DOI: 10.1159/000081732] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Accepted: 02/13/2004] [Indexed: 11/19/2022] Open
Abstract
Persistent expression of hepatitis B virus (HBV) proteins is thought to be involved in virus-related hepatocarcinogenesis. Here, we compared the gene expression profile of cells persistently expressing the full-length HBV with that of negative control cells to comprehensively investigate virus-mediated changes in the gene expression of the host cells. RNA samples from both virus-expressing and negative control cells were used for the DNA array assay. DNA array assay and subsequent corroboration assays revealed that expression of 14 of 1,176 genes (1.2%) was altered in response to virus expression. The upregulated genes included CD44, high mobility group protein-I, thymosin beta-10 and 27-kD heat shock protein, while the downregulated genes included NM23-H1, all of which are thought to be associated with the development or progression of carcinoma in the liver or other organs. Furthermore, virus expression resulted in the decrease of two apoptosis-inducing molecules, caspase-3 and BAX, which may also contribute to carcinogenesis through prolonged survival of the host cell. Thus, expression of the virus genome caused carcinogenesis-related changes in host cell gene expression. HBV expression may change the host cell to a malignant phenotype through alterations in the expression levels of a set of genes.
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Affiliation(s)
- Fumihiko Nakanishi
- Department of Internal Medicine and Therapeutic, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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Affiliation(s)
- Michael J Bouchard
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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Calzado MA, Sancho R, Muñoz E. Human immunodeficiency virus type 1 Tat increases the expression of cleavage and polyadenylation specificity factor 73-kilodalton subunit modulating cellular and viral expression. J Virol 2004; 78:6846-54. [PMID: 15194760 PMCID: PMC421638 DOI: 10.1128/jvi.78.13.6846-6854.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Tat protein, which is essential for HIV gene expression and viral replication, is known to mediate pleiotropic effects on various cell functions. For instance, Tat protein is able to regulate the rate of transcription of host cellular genes and to interact with the signaling machinery, leading to cellular dysfunction. To study the effect that HIV-1 Tat exerts on the host cell, we identified several genes that were up- or down-regulated in tat-expressing cell lines by using the differential display method. HIV-1 Tat specifically increases the expression of the cleavage and polyadenylation specificity factor (CPSF) 73-kDa subunit (CPSF3) without affecting the expression of the 160- and 100-kDa subunits of the CPSF complex. This complex comprises four subunits and has a key function in the 3'-end processing of pre-mRNAs by a coordinated interaction with other factors. CPSF3 overexpression experiments and knockdown of the endogenous CPSF3 by mRNA interference have shown that this subunit of the complex is an important regulatory protein for both viral and cellular gene expression. In addition to the known CPSF3 function in RNA polyadenylation, we also present evidence that this protein exerts transcriptional activities by repressing the mdm2 gene promoter. Thus, HIV-1-Tat up-regulation of CPSF3 could represent a novel mechanism by which this virus increases mRNA processing, causing an increase in both cell and viral gene expression.
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Affiliation(s)
- Marco A Calzado
- Departamento de Biología Celular, Fisiología e Inmunología, Facultad de Medicina, Universidad de Córdoba, Cordoba, Spain
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Chung TW, Lee YC, Kim CH. Hepatitis B viral HBx induces matrix metalloproteinase-9 gene expression through activation of ERK and PI-3K/AKT pathways: involvement of invasive potential. FASEB J 2004; 18:1123-5. [PMID: 15132991 DOI: 10.1096/fj.03-1429fje] [Citation(s) in RCA: 228] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hepatitis B virus (HBV) X protein (HBx) has been shown to be essential for the development of hepatocellular carcinoma (HCC). Recently, we have found that HBx causes the progression of liver cancer through down-expression of PTEN, known as a tumor suppressor gene (1). The prognosis for HCC depends mainly on the clinicopathological characteristic regarding invasion and metastasis. The expression of matrix metalloproteinase (MMP)-9 has been implicated as playing an important role in HCC invasion and metastasis. We previously reported that HBV infection increased the invasiveness of hepatocytes and HCC cells through the transcriptional activation of MMP-9 (2). The HBx was shown to activate the mitogen-activated protein (MAP) kinase and phosphatidylinositol 3-kinase (PI-3K) signal cascade, which is essential for activation of transcription factors such as activating protein (AP)-1 and nuclear factor (NF)-kappaB. In this study, we show that the HBx protein stimulates the activities of the PI-3K-Akt/ protein kinase B (PKB) as well as extracellular signal-regulated kinase 1/2 (ERK 1/2) in HBx-transfected cells. Furthermore, we have shown that enhanced expression of MMP-9 in HBx-transfected cells mediated by not only activation of AP-1 transcriptional activity through ERKs pathway but also activation of NF-kappaB transcriptional activity through PI-3K-AKT/PKB pathway, and was associated with the invasive potential. However, treatment with U0126 (known as the ERKs inhibitor) or wortmannin (known as the PI-3K inhibitor), but not SB203580 (known as the p38 MAPK inhibitor), markedly inhibited the expression of MMP-9 induced by HBx in HBx-transfected cells. Seemingly, the invasiveness of HBx-transfected cells was decreased by treating with U0126 or wortmannin, but not SB203580. These results clearly suggest that the HBx contributed to the transcriptional regulation of MMP-9 through the ERKs and PI-3K-AKT/PKB pathway, and increased an invasive potential of cells.
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Affiliation(s)
- Tae-Wook Chung
- National Research Laboratories for Glycobiology, Ministry of Science and Technolgoy, and Department of Biochemistry and Molecular Biology, College of Oriental Medicine, Dongguk University, Kyungju, South Korea
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