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Del Río-Álvarez Á, Carrillo-Reixach J, Royo L, Domingo-Sàbat M, Azkargorta M, Kapler R, Cairo S, Vokuhl C, de Krijger R, Alaggio R, Garrido M, Guillen G, Sábado C, Guerra L, Hernandez F, Mateos ME, López-Satamaría M, Torres B, Abad MP, Viera B, Czauderna P, Buendia MA, Elortza F, Wheatley K, Morland B, Armengol C. Abstract PO011: Proteomic profiling of childhood liver cancer: identification of novel diagnostic and prognostic biomarkers. Clin Cancer Res 2022. [DOI: 10.1158/1557-3265.liverca22-po011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Childhood liver cancers hepatoblastoma (HB) and hepatocellular carcinoma (HCC) are rare diseases but with a rising incidence. HEMNOS (Hepatocellular malignant neoplasm, not otherwise specified) is a recent entity with histopathological features of HB and HCC. Current chemotherapy treatments are effective to shrink tumor before surgery, nonetheless can cause severe lifelong adverse effects and are not effective for patients with aggressive and metastatic HB or HCC (~20% die due to the disease). The HB and HCC diagnosis is key to assign therapeutic regimens in the ongoing Pediatric Hepatic International Tumor Trial (PHITT); however, differential diagnosis for some patients is challenging due to the lack of specific biomarkers. Nowadays, there is an urgent need to identify diagnostic and prognostic biomarkers to improve the clinical management of childhood liver cancer. Herein, we aimed to uncover the proteomic profiles of different types of childhood liver cancer and identify new biomarkers for improving tumor diagnosis and early detection of the most aggressive cases. For this, 99 frozen tissue samples from 71 patients (mean age: 54.5 months, 60.6% boys, 40.9% metastasis, 23.7% deaths) including 70 primary tumors (57 HB, 8 HCC and 5 HEM-NOS), 22 non-tumors and 7 metastases were analyzed by label free mass spectrometry analysis. A total of 5,417 proteins were sequenced in the different samples. Through supervised analysis, we identified a total of 1302 differential expressed proteins in tumors as compared to non-tumor livers (FC +2 and FDR <0.01). A total of 246 proteins of them (19%) were commonly differently expressed in all tumors types; having HEMNOS a mixture of HB and HCC protein profiling. A panel of potential diagnostic biomarkers including 179, 120 and 81 upregulated proteins (FC >2) was defined for HB, HCC and HEM-NOS, respectively. Hierarchical unsupervised clustering and principal component analysis showed two main cluster of tumors: one including HB and HEM-NOS and another one with a mixture of HB, HEM-NOS and HCC. Interestingly, this second cluster was associated with clinical and molecular features of aggressive tumors such as multifocality (p = 0.029), Epigenetic Epi-CB subclass (p = 0.006), high-risk Molecular Risk Stratification (p = 0.009) and poor survival (log rank test=0.012). A total of 2082 proteins were found to be differently expressed between the two prognostic clusters (FC +2 and FDR < 0.01); the GEO enrichment analysis revealed that these proteins were significantly enriched in post-transcriptional gene silencing and RNA splicing mechanisms (FDR <10−7). In addition, a 25-protein signature associated to liver cancer prognosis was defined (FC>6 and FDR < 10−14). In conclusion, we identified a list of potential diagnostic and prognostic protein biomarkers that after a validation in large patient cohort, could be used to improve the clinical management of childhood liver cancer.
Citation Format: Álvaro Del Río-Álvarez, Juan Carrillo-Reixach, Laura Royo, Montse Domingo-Sàbat, Mikel Azkargorta, Roland Kapler, Stefano Cairo, Christian Vokuhl, Ronald de Krijger, Rita Alaggio, Marta Garrido, Gabriela Guillen, Constantino Sábado, Laura Guerra, Francisco Hernandez, Maria Elena Mateos, Manuel López-Satamaría, Barbara Torres, Maria Pilar Abad, Bajčiová Viera, Piotr Czauderna, Marie Annick Buendia, Felix Elortza, Keith Wheatley, Bruce Morland, Carolina Armengol. Proteomic profiling of childhood liver cancer: identification of novel diagnostic and prognostic biomarkers [abstract]. In: Proceedings of the AACR Special Conference: Advances in the Pathogenesis and Molecular Therapies of Liver Cancer; 2022 May 5-8; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(17_Suppl):Abstract nr PO011.
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Affiliation(s)
- Álvaro Del Río-Álvarez
- 1Childhood Liver Oncology Group (c-LOG), Health Sciences Research Institute Germans Trias i Pujol (IGTP), Badalona, Spain., Badalona, Spain,
| | - Juan Carrillo-Reixach
- 1Childhood Liver Oncology Group (c-LOG), Health Sciences Research Institute Germans Trias i Pujol (IGTP), Badalona, Spain., Badalona, Spain,
| | - Laura Royo
- 1Childhood Liver Oncology Group (c-LOG), Health Sciences Research Institute Germans Trias i Pujol (IGTP), Badalona, Spain., Badalona, Spain,
| | - Montse Domingo-Sàbat
- 2Childhood Liver Oncology Group (c-LOG), Health Sciences Research Institute Germans Trias i Pujol (IGTP), Badalona, Spain, Badalona, Spain,
| | - Mikel Azkargorta
- 3Proteomics Platform, CIC bioGUNE - ProteoRed-ISCIII, Derio, Spain., Derio, Spain,
| | - Roland Kapler
- 4Department of Pediatric Surgery, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University Munich, Lindwurmstr. 2a, 80337 Munich, Germany., Munich, Germany,
| | | | - Christian Vokuhl
- 6Section of Pediatric Pathology, Department of Pathology, University Hospital Bonn, Bonn, Germany., Bonn, Germany,
| | - Ronald de Krijger
- 7Princess Maxima Centre for Pediatric Oncology, Utrecht, Netherlands., Utrecht, Netherlands,
| | - Rita Alaggio
- 8Unit of Pathology, Children's Hospital Bambino Gesù IRCCS, Rome, Italy., Rome, Italy,
| | - Marta Garrido
- 9Hospital Vall d’Hebron, Pathology Department, Barcelona, Spain, Barcelona, Spain,
| | - Gabriela Guillen
- 10Hospital Vall d’Hebron, Pediatric Surgery Department, Barcelona, Spain, Barcelona, Spain,
| | - Constantino Sábado
- 11Hospital Vall d’Hebron, Pediatric Oncology Department, Barcelona, Spain, Barcelona, Spain,
| | - Laura Guerra
- 12University Hospital La Paz, Pathology Department, Madrid, Spain, Madrid, Spain,
| | - Francisco Hernandez
- 13University Hospital La Paz, Pediatric Surgery Department, Madrid, Spain, Madrid, Spain,
| | - Maria Elena Mateos
- 14Pediatric Oncology Unit, Department of Pediatrics, University Hospital Reina Sofía, Córdoba, Spain, Cordoba, Spain,
| | - Manuel López-Satamaría
- 13University Hospital La Paz, Pediatric Surgery Department, Madrid, Spain, Madrid, Spain,
| | - Barbara Torres
- 15Medical Oncology Department, Pediatric Oncology Department, University Hospital La Fe, Valencia, Spain, Valencia, Spain,
| | - Maria Pilar Abad
- 16University Hospital Germans Trias i Pujol, Pediatric Surgery Department, Badalona, España., Badalona, SA, Spain,
| | - Bajčiová Viera
- 17Department of Pediatric Oncology, Childrens University Hospital Brno, Brno, Czech., Brno, Czech Republic,
| | - Piotr Czauderna
- 18Department of Surgery and Urology for Children and Adolescents, Medical University of Gdansk, Gdansk, Poland., Gdansk, Poland,
| | - Marie Annick Buendia
- 19INSERM, UMR 1193, Paul-Brousse Hospital, Hepatobiliary Centre F-94800 Villejuif France., Villejuif, France,
| | - Felix Elortza
- 3Proteomics Platform, CIC bioGUNE - ProteoRed-ISCIII, Derio, Spain., Derio, Spain,
| | - Keith Wheatley
- 20University of Birmingham Clinical Trials Unit, Park Grange, 1 Somerset Road, Edgbaston, Birmingham, Birmingham, United Kingdom,
| | - Bruce Morland
- 21Department of Oncology, Birmingham Women's and Children's Hospital, Birmingham, UK, Birmingham, United Kingdom
| | - Carolina Armengol
- 1Childhood Liver Oncology Group (c-LOG), Health Sciences Research Institute Germans Trias i Pujol (IGTP), Badalona, Spain., Badalona, Spain,
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Cougot D, Wu Y, Cairo S, Caramel J, Renard CA, Lévy L, Buendia MA, Neuveut C. Correction: The hepatitis B virus X protein functionally interacts with CREB-binding protein/p300 in the regulation of CREB-mediated transcription. J Biol Chem 2020; 295:2888. [PMID: 32111723 DOI: 10.1074/jbc.aac120.012898] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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3
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Hashimoto K, Suzuki AM, Dos Santos A, Desterke C, Collino A, Ghisletti S, Braun E, Bonetti A, Fort A, Qin XY, Radaelli E, Kaczkowski B, Forrest ARR, Kojima S, Samuel D, Natoli G, Buendia MA, Faivre J, Carninci P. CAGE profiling of ncRNAs in hepatocellular carcinoma reveals widespread activation of retroviral LTR promoters in virus-induced tumors. Genome Res 2015; 25:1812-24. [PMID: 26510915 PMCID: PMC4665003 DOI: 10.1101/gr.191031.115] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 09/30/2015] [Indexed: 12/20/2022]
Abstract
An increasing number of noncoding RNAs (ncRNAs) have been implicated in various human diseases including cancer; however, the ncRNA transcriptome of hepatocellular carcinoma (HCC) is largely unexplored. We used CAGE to map transcription start sites across various types of human and mouse HCCs with emphasis on ncRNAs distant from protein-coding genes. Here, we report that retroviral LTR promoters, expressed in healthy tissues such as testis and placenta but not liver, are widely activated in liver tumors. Despite HCC heterogeneity, a subset of LTR-derived ncRNAs were more than 10-fold up-regulated in the vast majority of samples. HCCs with a high LTR activity mostly had a viral etiology, were less differentiated, and showed higher risk of recurrence. ChIP-seq data show that MYC and MAX are associated with ncRNA deregulation. Globally, CAGE enabled us to build a mammalian promoter map for HCC, which uncovers a new layer of complexity in HCC genomics.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B/genetics
- Animals
- Carcinoma, Hepatocellular/etiology
- Carcinoma, Hepatocellular/pathology
- Cell Line, Tumor
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Viral
- Computational Biology/methods
- Disease Models, Animal
- Disease Progression
- Gene Expression Profiling/methods
- Gene Expression Regulation, Neoplastic
- Humans
- Liver Neoplasms/etiology
- Liver Neoplasms/pathology
- Mice
- Mice, Knockout
- Promoter Regions, Genetic
- Protein Binding
- RNA, Untranslated/genetics
- Terminal Repeat Sequences
- Transcription Factors/metabolism
- Transcription Initiation Site
- Transcriptome
- ATP-Binding Cassette Sub-Family B Member 4
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Affiliation(s)
- Kosuke Hashimoto
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Yokohama, Kanagawa, 230-0045 Japan
| | - Ana Maria Suzuki
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Yokohama, Kanagawa, 230-0045 Japan
| | - Alexandre Dos Santos
- INSERM, U1193, Paul-Brousse Hospital, Hepatobiliary Centre, 94800 Villejuif, France; Université Paris Saclay, Faculté de Médecine Le Kremlin Bicêtre, 94800 Villejuif, France
| | - Christophe Desterke
- INSERM, U1193, Paul-Brousse Hospital, Hepatobiliary Centre, 94800 Villejuif, France; Université Paris Saclay, Faculté de Médecine Le Kremlin Bicêtre, 94800 Villejuif, France
| | - Agnese Collino
- European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, 20139 Milan, Italy
| | - Serena Ghisletti
- European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, 20139 Milan, Italy
| | - Emilie Braun
- INSERM, U1193, Paul-Brousse Hospital, Hepatobiliary Centre, 94800 Villejuif, France; Université Paris Saclay, Faculté de Médecine Le Kremlin Bicêtre, 94800 Villejuif, France
| | - Alessandro Bonetti
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Yokohama, Kanagawa, 230-0045 Japan
| | - Alexandre Fort
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Yokohama, Kanagawa, 230-0045 Japan
| | - Xian-Yang Qin
- RIKEN Center for Life Science Technologies, Division of Bio-function Dynamics Imaging, Wako, Saitama, 351-0198, Japan
| | - Enrico Radaelli
- VIB Center for the Biology of Disease, KU Leuven Center for Human Genetics, B-3000 Leuven, Belgium
| | - Bogumil Kaczkowski
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Yokohama, Kanagawa, 230-0045 Japan
| | - Alistair R R Forrest
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Yokohama, Kanagawa, 230-0045 Japan
| | - Soichi Kojima
- RIKEN Center for Life Science Technologies, Division of Bio-function Dynamics Imaging, Wako, Saitama, 351-0198, Japan
| | - Didier Samuel
- INSERM, U1193, Paul-Brousse Hospital, Hepatobiliary Centre, 94800 Villejuif, France; Université Paris Saclay, Faculté de Médecine Le Kremlin Bicêtre, 94800 Villejuif, France
| | - Gioacchino Natoli
- European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, 20139 Milan, Italy
| | - Marie Annick Buendia
- INSERM, U1193, Paul-Brousse Hospital, Hepatobiliary Centre, 94800 Villejuif, France; Université Paris Saclay, Faculté de Médecine Le Kremlin Bicêtre, 94800 Villejuif, France
| | - Jamila Faivre
- INSERM, U1193, Paul-Brousse Hospital, Hepatobiliary Centre, 94800 Villejuif, France; Université Paris Saclay, Faculté de Médecine Le Kremlin Bicêtre, 94800 Villejuif, France; Assistance Publique-Hôpitaux de Paris (AP-HP), Pôle de Biologie Médicale, Paul-Brousse Hospital, 94800 Villejuif, France
| | - Piero Carninci
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Yokohama, Kanagawa, 230-0045 Japan
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4
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Iannelli F, Collino A, Sinha S, Radaelli E, Nicoli P, D’Antiga L, Sonzogni A, Faivre J, Buendia MA, Sturm E, Thompson RJ, Knisely AS, Natoli G, Ghisletti S, Ciccarelli FD. Erratum: Corrigendum: Massive gene amplification drives paediatric hepatocellular carcinoma caused by bile salt export pump deficiency. Nat Commun 2015; 6:7456. [DOI: 10.1038/ncomms8456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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5
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6
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Iannelli F, Collino A, Sinha S, Radaelli E, Nicoli P, D'Antiga L, Sonzogni A, Faivre J, Buendia MA, Sturm E, Thompson RJ, Knisely AS, Natoli G, Ghisletti S, Ciccarelli FD. Massive gene amplification drives paediatric hepatocellular carcinoma caused by bile salt export pump deficiency. Nat Commun 2014; 5:3850. [PMID: 24819516 DOI: 10.1038/ncomms4850] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 04/10/2014] [Indexed: 12/19/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is almost invariably associated with an underlying inflammatory state, whose direct contribution to the acquisition of critical genomic changes is unclear. Here we map acquired genomic alterations in human and mouse HCCs induced by defects in hepatocyte biliary transporters, which expose hepatocytes to bile salts and cause chronic inflammation that develops into cancer. In both human and mouse cancer genomes, we find few somatic point mutations with no impairment of cancer genes, but massive gene amplification and rearrangements. This genomic landscape differs from that of virus- and alcohol-associated liver cancer. Copy-number gains preferentially occur at late stages of cancer development and frequently target the MAPK signalling pathway, and in particular direct regulators of JNK. The pharmacological inhibition of JNK retards cancer progression in the mouse. Our study demonstrates that intrahepatic cholestasis leading to hepatocyte exposure to bile acids and inflammation promotes cancer through genomic modifications that can be distinguished from those determined by other aetiological factors.
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Affiliation(s)
- Fabio Iannelli
- 1] European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, Via Adamello 16, 20139 Milan, Italy [2]
| | - Agnese Collino
- 1] European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, Via Adamello 16, 20139 Milan, Italy [2]
| | - Shruti Sinha
- 1] European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, Via Adamello 16, 20139 Milan, Italy [2] Division of Cancer Studies, King's College London, London SE1 1UL, UK [3]
| | - Enrico Radaelli
- VIB Center for the Biology of Disease, KU Leuven Center for Human Genetics, O&N4 Herestraat 49 box 602, B-3000 Leuven, Belgium
| | - Paola Nicoli
- European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, Via Adamello 16, 20139 Milan, Italy
| | - Lorenzo D'Antiga
- Paediatric Hepatology, Gastroenterology and Transplantation, Ospedale Papa Giovanni XXIII, Piazza OMS - Organizzazione Mondiale della Sanità 1, 24128 Bergamo, Italy
| | - Aurelio Sonzogni
- Department of Pathology, Ospedale Papa Giovanni XXIII, Piazza OMS - Organizzazione Mondiale della Sanità 1, 24128 Bergamo, Italy
| | - Jamila Faivre
- Institut National de la Santé et de la Recherche Médicale (INSERM) U785, University Paris-Sud, France, Centre Hépatobiliaire, Hôpital Paul Brousse, Villejuif F94800, France
| | - Marie Annick Buendia
- Institut National de la Santé et de la Recherche Médicale (INSERM) U785, University Paris-Sud, France, Centre Hépatobiliaire, Hôpital Paul Brousse, Villejuif F94800, France
| | - Ekkehard Sturm
- University Hospital for Children and Adolescents, University of Tuebingen, 72076 Tuebingen, Germany
| | | | - A S Knisely
- Institute of Liver Studies, King's College Hospital, London SE5 9RS, UK
| | - Gioacchino Natoli
- European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, Via Adamello 16, 20139 Milan, Italy
| | - Serena Ghisletti
- European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, Via Adamello 16, 20139 Milan, Italy
| | - Francesca D Ciccarelli
- 1] European Institute of Oncology (IEO), Department of Experimental Oncology, IFOM-IEO Campus, Via Adamello 16, 20139 Milan, Italy [2] Division of Cancer Studies, King's College London, London SE1 1UL, UK
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7
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Abstract
The hepatitis B virus (HBV) is a small enveloped DNA virus that causes acute and chronic hepatitis. HBV infection is a world health problem, with 350 million chronically infected people at increased risk of developing liver disease and hepatocellular carcinoma (HCC). HBV has been classified among human tumor viruses by virtue of a robust epidemiologic association between chronic HBV carriage and HCC occurrence. In the absence of cytopathic effect in infected hepatocytes, the oncogenic role of HBV might involve a combination of direct and indirect effects of the virus during the multistep process of liver carcinogenesis. Liver inflammation and hepatocyte proliferation driven by host immune responses are recognized driving forces of liver cell transformation. Genetic and epigenetic alterations can also result from viral DNA integration into host chromosomes and from prolonged expression of viral gene products. Notably, the transcriptional regulatory protein HBx encoded by the X gene is endowed with tumor promoter activity. HBx has pleiotropic activities and plays a major role in HBV pathogenesis and in liver carcinogenesis. Because hepatic tumors carry a dismal prognosis, there is urgent need to develop early diagnostic markers of HCC and effective therapies against chronic hepatitis B. Deciphering the oncogenic mechanisms that underlie HBV-related tumorigenesis might help developing adapted therapeutic strategies.
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Affiliation(s)
- Lise Rivière
- Institut Pasteur, Hepacivirus and Innate Immunity Unit, 28 rue du Dr Roux, 75015, Paris, France,
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8
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Studach LL, Menne S, Cairo S, Buendia MA, Hullinger RL, Lefrançois L, Merle P, Andrisani OM. Subset of Suz12/PRC2 target genes is activated during hepatitis B virus replication and liver carcinogenesis associated with HBV X protein. Hepatology 2012; 56:1240-51. [PMID: 22505317 PMCID: PMC3417088 DOI: 10.1002/hep.25781] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
UNLABELLED Chronic hepatitis B virus (HBV) infection is a major risk factor for developing liver cancer, and the HBV X protein (pX) has been implicated as a cofactor in hepatocyte transformation. We have shown that HBV replication as well as in vitro transformation by pX are associated with induction of the mitotic polo-like kinase 1 (Plk1) and down-regulation of the chromatin remodeling components Suz12 and Znf198. Herein, we demonstrate the same inverse relationship between Plk1 and Suz12/Znf198 in liver tumors from X/c-myc bitransgenic mice and woodchuck hepatitis virus (WHV)-infected woodchucks. Employing these animal models and the HBV replicating HepAD38 cells we examined the effect of Suz12/Znf198 down-regulation on gene expression. Genes analyzed include hepatic cancer stem cell markers BAMBI, DKK1,2, DLK1, EpCAM, MYC, and proliferation genes CCNA1, CCND2, IGFII, MCM4-6, PLK1, RPA2, and TYMS. Suz12 occupancy at the promoters of BAMBI, CCND2, DKK2, DLK1, EpCAM, and IGFII was demonstrated by chromatin immunoprecipitation in untransformed hepatocytes, but was markedly reduced in pX-transformed and Suz12 knockdown cells. Accordingly, we refer to these genes as "Suz12 repressed" genes in untransformed hepatocytes. The Suz12 repressed genes and proliferation genes were induced in HBV-replicating HepAD38 cells and, interestingly, they exhibited distinct expression profiles during hepatocellular carcinoma (HCC) progression in X/c-myc bitransgenics. Specifically, CCND2, EpCAM, and IGFII expression was elevated at the proliferative and preneoplastic stages in X/c-myc bitransgenic livers, whereas BAMBI and PLK1 were overexpressed in hepatic tumors from X/c-myc bitransgenics and WHV-infected woodchucks. Importantly, most of these genes were selectively up-regulated in HBV-induced HCCs. CONCLUSION The distinct expression profile of the identified Suz12 repressed genes in combination with the proliferation genes hold promise as biomarkers for progression of chronic HBV infection to HCC.
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MESH Headings
- Animals
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/virology
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/pathology
- Cells, Cultured
- Disease Models, Animal
- Down-Regulation
- Gene Expression Regulation, Viral
- Hepatitis B virus/genetics
- Hepatitis B, Chronic/genetics
- Hepatitis B, Chronic/physiopathology
- Hepatocytes/pathology
- Liver Neoplasms/genetics
- Liver Neoplasms/virology
- Marmota
- Mice
- Mice, Transgenic
- Polycomb Repressive Complex 2/genetics
- Polycomb Repressive Complex 2/metabolism
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- Random Allocation
- Sensitivity and Specificity
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcriptional Activation
- Viral Regulatory and Accessory Proteins
- Virus Replication/genetics
- Polo-Like Kinase 1
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Affiliation(s)
- Leo L. Studach
- Department of Basic Medical Sciences and Purdue University Center for Cancer Research, West Lafayette, IN, USA
| | - Stephan Menne
- Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, DC, USA
| | - Stefano Cairo
- XenTech, Research and Development Department, Genopole Campus 3 Evry, France
| | - Marie Annick Buendia
- Inserm U785 Unit, Hepatobiliary Center, Paul Brousse Hospital, Villejuif, France
| | - Ronald L. Hullinger
- Department of Basic Medical Sciences and Purdue University Center for Cancer Research, West Lafayette, IN, USA
| | - Lydie Lefrançois
- Inserm U1052, Centre de Recherche en Cancérologie de Lyon, Hepatocarcinogenesis and Viral Infection, Lyon Cedex 03 France
| | - Philippe Merle
- Inserm U1052, Centre de Recherche en Cancérologie de Lyon, Hepatocarcinogenesis and Viral Infection, Lyon Cedex 03 France
| | - Ourania M. Andrisani
- Department of Basic Medical Sciences and Purdue University Center for Cancer Research, West Lafayette, IN, USA
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9
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Cairo S, Buendia MA. How transient becomes stable: an epigenetic switch linking liver inflammation and tumorigenesis. J Hepatol 2012; 57:910-2. [PMID: 22668642 DOI: 10.1016/j.jhep.2012.05.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 05/22/2012] [Accepted: 05/22/2012] [Indexed: 12/04/2022]
Affiliation(s)
- Stefano Cairo
- XenTech, Research and Development Department, Evry, France
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10
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Abstract
Hepatoblastoma (HB) is the most common type of pediatric liver cancer. This tumor is thought to derive from hepatic progenitor cells that are arrested at various stages of liver development, as illustrated by a variety of histologic subtypes. Recent genomic studies have led to better understand the molecular pathogenesis of HB, to point out the crucial roles of the Wnt Myc signaling pathways in malignant transformation of liver progenitor cells. Molecular classification of HB based on genome-wide studies, as well as identification of reliable diagnostic prognostic markers, open the way to the development of new personalized targeted therapies for the management of aggressive lethal childhood tumors.
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11
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Abstract
The hepatitis B virus (HBV) is a small enveloped DNA virus, which primarily infects hepatocytes and causes acute and persistent liver disease. Epidemiological studies have provided overwhelming evidence for a causal role of chronic HBV infection in the development of hepatocellular carcinoma, but the molecular mechanisms underlying virally-induced tumourigenesis remain largely debated. In the absence of a dominant oncogene encoded by the HBV genome, indirect roles have been proposed, including insertional activation of cellular cancer-related genes by HBV DNA integration, induction of genetic instability by viral integration or by the regulatory protein HBx, and long-term effects of viral proteins in enhancing immune-mediated liver disease. Recent genetic studies indicate that HBV-related tumours display a distinctive profile with a high rate of chromosomal alterations and low frequency of beta-catenin mutations. This review will discuss the evidence implicating chronic HBV infection as a causal risk factor of primary liver cancer. It will also discuss the molecular mechanisms that are critical for the tumourigenic process due to long lasting infection with HBV.
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Affiliation(s)
- Christine Neuveut
- Oncogenesis and Molecular Virology Unit, Institut Pasteur, Inserm U579, 28 rue du Dr Roux, Paris cedex 15, France
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12
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Armengol C, Cairo S, Fabre M, Buendia MA. Wnt signaling and hepatocarcinogenesis: the hepatoblastoma model. Int J Biochem Cell Biol 2009; 43:265-70. [PMID: 19646548 DOI: 10.1016/j.biocel.2009.07.012] [Citation(s) in RCA: 211] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 07/20/2009] [Accepted: 07/21/2009] [Indexed: 11/15/2022]
Abstract
The Wnt/β-catenin pathway plays a key role in liver development, regeneration and tumorigenesis. Among human cancers tightly linked to abnormal Wnt/β-catenin signaling, hepatoblastoma (HB) presents with the highest rate (50-90%) of β-catenin mutations. HB is the most common malignant tumor of the liver in childhood. This embryonic tumor differs from hepatocellular carcinoma by the absence of viral etiology and underlying liver disease, and by distinctive morphological patterns evoking hepatoblasts, the bipotent precursors of hepatocytes and cholangiocytes. Recent studies of the molecular pathogenesis of hepatoblastoma have led to identify two major tumor subclasses resembling early and late phases of prenatal liver development and presenting distinctive chromosomal alterations. It has been shown that the molecular signature of Wnt/β-catenin signaling in hepatoblastoma is mainly imposed by liver context, but differs according to developmental stage. Finally, the differentiation stage of tumor cells strongly influences their invasive and metastatic properties, therefore affecting clinical behavior.
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Affiliation(s)
- C Armengol
- Oncogenesis and Molecular Virology Unit, Institut Pasteur, Inserm U579, Paris, France
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13
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14
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Cougot D, Wu Y, Cairo S, Caramel J, Renard CA, Lévy L, Buendia MA, Neuveut C. The hepatitis B virus X protein functionally interacts with CREB-binding protein/p300 in the regulation of CREB-mediated transcription. J Biol Chem 2006; 282:4277-4287. [PMID: 17158882 DOI: 10.1074/jbc.m606774200] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The hepatitis B virus infects more than 350 million people worldwide and is a leading cause of liver cancer. The virus encodes a multifunctional regulator, the hepatitis B virus X protein (HBx), that is essential for virus replication. HBx is involved in modulating signal transduction pathways and transcription mediated by various factors, notably CREB that requires the recruitment of the co-activators CREB-binding protein (CBP)/p300. Here we investigated the role of HBx and its potential interaction with CBP/p300 in regulating CREB transcriptional activity. We show that HBx and CBP/p300 synergistically enhanced CREB activity and that CREB phosphorylation by protein kinase A was a prerequisite for the cooperative action of HBx and CBP/p300. We further show that HBx interacted directly with CBP/p300 in vitro and in vivo. Using chromatin immunoprecipitation, we provide evidence that HBx physically occupied the CREB-binding domain of CREB-responsive promoters of endogenous cellular genes such as interleukin 8 and proliferating cell nuclear antigen. Moreover expression of HBx increased the recruitment of p300 to the interleukin 8 and proliferating cell nuclear antigen promoters in cells, and this is associated with increased gene expression. As recruitment of CBP/p300 is known to represent the limiting event for activating CREB target genes, HBx may disrupt this cellular regulation, thus predisposing cells to transformation.
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Affiliation(s)
- Delphine Cougot
- Unité d'Oncogene`se et Virologie Moléculaire, Institut Pasteur and INSERM U579, 28 rue du Dr. Roux, 75015 Paris, France
| | - Yuanfei Wu
- Unité d'Oncogene`se et Virologie Moléculaire, Institut Pasteur and INSERM U579, 28 rue du Dr. Roux, 75015 Paris, France
| | - Stefano Cairo
- Unité d'Oncogene`se et Virologie Moléculaire, Institut Pasteur and INSERM U579, 28 rue du Dr. Roux, 75015 Paris, France
| | - Julie Caramel
- Unité d'Oncogene`se et Virologie Moléculaire, Institut Pasteur and INSERM U579, 28 rue du Dr. Roux, 75015 Paris, France
| | - Claire-Angélique Renard
- Unité d'Oncogene`se et Virologie Moléculaire, Institut Pasteur and INSERM U579, 28 rue du Dr. Roux, 75015 Paris, France
| | - Laurence Lévy
- Unité d'Oncogene`se et Virologie Moléculaire, Institut Pasteur and INSERM U579, 28 rue du Dr. Roux, 75015 Paris, France
| | - Marie Annick Buendia
- Unité d'Oncogene`se et Virologie Moléculaire, Institut Pasteur and INSERM U579, 28 rue du Dr. Roux, 75015 Paris, France
| | - Christine Neuveut
- Unité d'Oncogene`se et Virologie Moléculaire, Institut Pasteur and INSERM U579, 28 rue du Dr. Roux, 75015 Paris, France.
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15
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Abstract
Hepatocellular carcinoma (HCC) is one of the rare human neoplasms associated with viral infections. Hepatitis B virus (HBV) and hepatitis C virus (HCV) are the most important etiological factors of HCC, accounting for more than 70% of cases worldwide. The risk of HCC development is greatly increased in chronic viral carriers exposed to other recognized risk factors, including exposure to aflatoxin B1, alcoholic cirrhosis and diabetes. The importance of HBV genotypes and precore or core promoter mutants remains incompletely understood. The role of HBV in tumour formation appears to be complex and may involve both direct and indirect mechanisms. Integration of HBV DNA into the host genome occurs at early steps of clonal tumour expansion, and it has been shown to induce direct insertional mutagenesis of diverse cancer-related genes in a number of cases. Chronic liver inflammation and hepatic regeneration induced by cellular immune responses may favour the accumulation of genetic alterations in infected hepatocytes. Prolonged expression of the viral regulatory protein HBx and the large envelope protein LHBs may contribute in deregulating the cellular transcription program and proliferation control, and sensitize liver cells to carcinogenic factors. Recent genetic studies have provided insight into the mechanisms underlying viral-associated hepatocarcinogenesis. It has been shown that the rate of chromosomal alterations is significantly increased in HBV-related tumours compared with tumours associated with other risk factors. HBV might therefore play a role in enhancing genomic instability. Inactivation of p53 by mutations and regional allelic deletions is found more frequently in tumours associated with HBV infection. By contrast, HBV related tumours harbour a low rate of beta-catenin mutations. Together, these data strongly support the notion that chronic HBV infection might trigger specific oncogenic pathways, thus playing a role beyond stimulation of host immune responses and chronic necro-inflammatory liver disease.
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Affiliation(s)
- Delphine Cougot
- Oncogenesis and Molecular Virology Unit, INSERM U579, Institut Pasteur, Paris, France
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16
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Abstract
This review on the pathology of hepatic tumors in childhood, from a personal series of 245 tumors, focuses on incidence, management, description of frequent tumors such as hepatoblastoma, fibrolamellar carcinoma, and undifferentiated sarcoma for malignant tumors, focal nodular hyperplasia, hepatocellular adenoma, and mesenchymal hamartoma for benign tumors. Malignant and benign entities of recent description, including the following: crowded, small cell undifferentiated and cholangioblastic variants of hepatoblastomas, mesenchymal hamartoma miming hepatoblastoma, liver adenoma and adenomatosis in diabete MODY3 families, gastrointestinal stromal tumor with liver metastasis associated to Carney triad, macronodules in non-cirrhotic portal fibrosis are reviewed. For each entity, the clinical presentation, the diagnostic criteria and the differential diagnosis are described. The role of immunohistochemistry and molecular biology in the diagnosis and identification of new molecular mechanisms triggered by oncogenic activation with new prognostic markers, and therapeutic targets is emphasized.
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Affiliation(s)
- Monique Fabre
- Service d'Anatomie et de Cytologie Pathologiques, Faculté de Médecine Paris XI et Hôpital de Bicêtre, 78, rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France.
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17
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Chang J, Nicolas E, Marks D, Sander C, Lerro A, Buendia MA, Xu C, Mason WS, Moloshok T, Bort R, Zaret KS, Taylor JM. miR-122, a mammalian liver-specific microRNA, is processed from hcr mRNA and may downregulate the high affinity cationic amino acid transporter CAT-1. RNA Biol 2004; 1:106-13. [PMID: 17179747 DOI: 10.4161/rna.1.2.1066] [Citation(s) in RCA: 632] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
These studies show that miR-122, a 22-nucleotide microRNA, is derived from a liver-specific noncoding polyadenylated RNA transcribed from the gene hcr. The exact sequence of miR-122 as well as the adjacent secondary structure within the hcr mRNA are conserved from mammalian species back to fish. Levels of miR-122 in the mouse liver increase to half maximal values around day 17 of embryogenesis, and reach near maximal levels of 50,000 copies per average cell before birth. Lewis et al. (2003) predicted the cationic amino acid transporter (CAT-1 or SLC7A1) as a miR-122 target. CAT-1 protein and its mRNA are expressed in all mammalian tissues but with lower levels in adult liver. Furthermore, during mouse liver development CAT-1 mRNA decreases in an almost inverse correlation with miR-122. Eight potential miR-122 target sites were predicted within the human CAT-1 mRNA, with six in the 3'-untranslated region. Using a reporter construct it was found that just three of the predicted sites, linked in a 400-nucleotide sequence from human CAT-1, acted with synergy and were sufficient to strongly inhibit protein synthesis and reduce mRNA levels. In summary, these studies followed the accumulation during development of miR-122 from its mRNA precursor, hcr, through to identification of what may be a specific mRNA target, CAT-1.
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Affiliation(s)
- Jinhong Chang
- Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111-2497, USA
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18
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Abstract
Lysine acetylation modulates the activities of nonhistone regulatory proteins and plays a critical role in the regulation of cellular gene transcription. In this study, we showed that the transcriptional coactivator p300 acetylated beta-catenin at lysine 345, located in arm repeat 6, in vitro and in vivo. Acetylation of this residue increased the affinity of beta-catenin for Tcf4, and the cellular Tcf4-bound pool of beta-catenin was significantly enriched in acetylated form. We demonstrated that the acetyltransferase activity of p300 was required for efficient activation of transcription mediated by beta-catenin/Tcf4 and that the cooperation between p300 and beta-catenin was severely reduced by the K345R mutation, implying that acetylation of beta-catenin plays a part in the coactivation of beta-catenin by p300. Interestingly, acetylation of beta-catenin had opposite, negative effects on the binding of beta-catenin to the androgen receptor. Our data suggest that acetylation of beta-catenin in the arm 6 domain regulates beta-catenin transcriptional activity by differentially modulating its affinity for Tcf4 and the androgen receptor. Thus, our results describe a new mechanism by which p300 might regulate beta-catenin transcriptional activity.
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Affiliation(s)
- Laurence Lévy
- Unité d'Oncogenèse et Virologie Moléculaire (INSERM U579), Institut Pasteur, 75015 Paris, France
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19
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Lévy L, Neuveut C, Renard CA, Charneau P, Branchereau S, Gauthier F, Van Nhieu JT, Cherqui D, Petit-Bertron AF, Mathieu D, Buendia MA. Transcriptional activation of interleukin-8 by beta-catenin-Tcf4. J Biol Chem 2002; 277:42386-93. [PMID: 12200448 DOI: 10.1074/jbc.m207418200] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Nuclear translocation of beta-catenin and its association with Tcf/Lef factors are key steps in transduction of the Wnt signal, which is aberrantly activated in a variety of human cancers. In a search for new beta-catenin-Tcf target genes, we analyzed beta-catenin-induced alterations of gene expression in primary human hepatocytes, after transduction of either dominant stable beta-catenin or its truncated, transactivation-deficient counterpart by means of a lentiviral vector. cDNA microarray analysis revealed a limited set of up-regulated genes, including known Wnt targets such as matrilysin and keratin-1. In this screen, we identified the CXC chemokine interleukin 8 (IL-8) as a direct target of beta-catenin-Tcf4. IL-8 is constitutively expressed in various cancers, and it has been implicated in tumor progression through its mitogenic, motogenic, and angiogenic activities. The IL-8 promoter contains a unique consensus Tcf/Lef site that is critical for IL-8 activation by beta-catenin. We show here that the p300 coactivator was required for efficient transactivation of beta-catenin on this promoter. Ectopic expression of beta-catenin in hepatoma cells promoted IL-8 secretion, which stimulated endothelial cell migration. These data define IL-8 as a Wnt target and suggest that IL-8 induction by beta-catenin might be implicated in developmental and tumorigenic processes.
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Affiliation(s)
- Laurence Lévy
- Unité de Recombinaison et Expression Génétique (Inserm U163), Département de Médecine Moléculaire, Institut Pasteur, 28 rue du Dr. Roux, 75015 Paris, France
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20
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Abstract
Hepatoblastoma (HB) and hepatocellular carcinoma (HCC) are two different subtypes of primary tumors arising from liver parenchymal cells. These tumors differ by many histoclinical characteristics, and comparative analysis of genetic alterations in HB and HCC might provide some clues on the molecular oncogenic pathways leading to hepatocyte transformation. Recent outcomes have been provided by the assessment of global genetic changes in tumor cells, using conventional cytogenetic approaches, PCR-based microsatellite analysis and Comparative genomic Hybridization (CGH). Cytogenetic studies of HB, microsatellite analysis of HCC and recent CHG data have outlined common and distinctive characters between the two tumor types. HBs are characterized by a low number of chromosomal changes, consisting mainly of gains at chromosomes 1q, 2, 8q, 17q, and 20. By contrast, HCCs harbor multiple chromosomal abnormalities, predominantly losses, with increased chromosomal instability in tumors associated with hepatitis B virus infection. Common alterations in HB and HCC include gain of chromosomes 1q, 8q, and 17q, and loss of 4q. Another important common feature shared by the two tumor types is the frequent activation of Wnt/beta-catenin signaling by stabilizing mutations of beta-catenin. Immunohistochemical analysis of beta-catenin has demonstrated nuclear/cytoplasmic accumulation of the protein in most HBs and in more than one third of HCCs. Strikingly, beta-catenin mutations are associated with chromosomal stability in both tumor types. Together, these studies define different pathways in liver cell transformation, reflecting various developmental stages and multiple risk factors. A detailed understanding of the molecular hits underlying liver tumorigenesis, combined with clinicopathological parameters, will permit an accurate evaluation of major targets for prognostic and therapeutic intervention.
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Affiliation(s)
- Marie Annick Buendia
- Unité de Recombinaison et Expression Génétique, Inserm U163, Département des Retrovirus, Institut Pasteur, Paris, France.
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21
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Abstract
Hepatocellular carcinoma (HCC) is a major type of primary liver cancer and one of the rare human neoplasms etiologically linked to viral factors. Chronic infections with the hepatitis B virus (HBV) and the hepatitis C virus (HCV) have been implicated in about 80% of cases worldwide, and other known environmental risk factors, including alcohol abuse and dietary intake of aflatoxin B1, might synergize with viral infections. Recent insight into the molecular mechanisms leading to HCC development has been provided by the identification of major genetic abnormalities revealed by genomewide allelotype studies and molecular cytogenetic analysis. Moreover, several oncogenic pathways have been implicated in malignant transformation of liver cells. Inactivation of the p53 tumor suppressor gene by mutations and allelic deletions in about 30% of HCC cases has been associated predominantly with exposure to aflatoxin B1 and HBV infection. By contrast, a mutation in the beta-catenin gene in around 22% of HCCs is more rare in HBV-associated tumors. Activation of cyclin D1 and disruption of the Rb pathway are also commonly involved in liver tumorigenesis. New major challenges include the identification of candidate genes located in frequently altered chromosomal regions and that of oncogenic pathways driven by different risk factors. This search might shed some light on the tumorigenic role of HBV and HCV. It might also permit accurate evaluation of major targets for prognostic and therapeutic intervention.
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Affiliation(s)
- Laurence Lévy
- Unité de Recombinaison et Expression Génétique, INSERM U163, Département des Rétrovirus, Institut Pasteur, 75015 Paris, France
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22
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Wu Y, Renard CA, Apiou F, Huerre M, Tiollais P, Dutrillaux B, Buendia MA. Recurrent allelic deletions at mouse chromosomes 4 and 14 in Myc-induced liver tumors. Oncogene 2002; 21:1518-26. [PMID: 11896580 DOI: 10.1038/sj.onc.1205208] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2001] [Revised: 11/12/2001] [Accepted: 11/28/2001] [Indexed: 02/02/2023]
Abstract
Transgenic mice expressing the c-Myc oncogene driven by woodchuck hepatitis virus (WHV) regulatory sequences develop hepatocellular carcinoma with a high frequency. To investigate genetic lesions that cooperate with Myc in liver carcinogenesis, we conducted a genome-wide scan for loss of heterozygosity (LOH) and mutational analysis of beta-catenin in 37 hepatocellular adenomas and carcinomas from C57BL/6 x castaneus F1 transgenic mice. In a subset of these tumors, chromosome imbalances were examined by comparative genomic hybridization (CGH). Allelotyping with 99 microsatellite markers spanning all autosomes revealed allelic imbalances at one or more chromosomes in 83.8% of cases. The overall fractional allelic loss was rather low, with a mean index of 0.066. However, significant LOH rates involved chromosomes 4 (21.6% of tumors), 14, 9 and 1 (11 to 16%). Interstitial LOH on chromosome 4 was mapped at band C4-C7 that contains the INK4a/ARF and INK4b loci, and on chromosome 14 at band B-D including the RB locus. In man, the homologous chromosomal regions 9p21, 13q14 and 8p21-23 are frequently deleted in liver cancer. LOH at chromosomes 1 and 14, and beta-catenin mutations (12.5% of cases) were seen only in HCCs. All tumors examined were found to be aneuploid. CGH analysis of 10 representative cases revealed recurrent gains at chromosomes 16 and 19, but losses or deletions involving mostly chromosomes 4 and 14 generally prevailed over gains. Thus, Myc activation in the liver might select for inactivation of tumor suppressor genes on regions of chromosomes 4 and 14 in a context of low genomic instability. Myc transgenic mice provide a useful model for better defining crosstalks between oncogene and tumor suppressor pathways in liver tumorigenesis.
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MESH Headings
- Adenoma, Liver Cell/etiology
- Adenoma, Liver Cell/genetics
- Animals
- Carcinoma, Hepatocellular/etiology
- Carcinoma, Hepatocellular/genetics
- Chromosome Mapping
- Cytoskeletal Proteins/genetics
- DNA Mutational Analysis
- DNA, Neoplasm/analysis
- Flow Cytometry
- Genes, myc
- Hepatitis B Virus, Woodchuck/genetics
- Liver Neoplasms, Experimental/etiology
- Liver Neoplasms, Experimental/genetics
- Loss of Heterozygosity
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Microscopy, Fluorescence
- Nucleic Acid Hybridization
- Ploidies
- Trans-Activators
- beta Catenin
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Affiliation(s)
- Yuanfei Wu
- Unité de Recombinaison et Expression Génétique (Inserm U163), Institut Pasteur, 28 rue du Dr. Roux, 75015 Paris, France
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23
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Amicone L, Terradillos O, Calvo L, Costabile B, Cicchini C, Della Rocca C, Lozupone F, Piacentini M, Buendia MA, Tripodi M. Synergy between truncated c-Met (cyto-Met) and c-Myc in liver oncogenesis: importance of TGF-beta signalling in the control of liver homeostasis and transformation. Oncogene 2002; 21:1335-45. [PMID: 11857077 DOI: 10.1038/sj.onc.1205199] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2001] [Revised: 11/26/2001] [Accepted: 11/26/2001] [Indexed: 11/08/2022]
Abstract
The c-Met tyrosine kinase receptor and its ligand, Hepatocyte Growth Factor/ Scatter Factor, have been implicated in human cancer. We have previously described that the transgenic expression of a truncated form of human c-Met (cyto-Met) in the liver confers resistance to several apoptotic stimuli. Here we show the impact of cyto-Met expression on liver proliferation and transformation. Despite a sixfold increase of hepatocyte proliferation, adult transgenic livers displayed normal size and architecture. We present evidence showing that activation of TGF-beta1 signalling controls the liver mass in cyto-Met mice. The oncogenic potential of cyto-Met was further assessed in the context of c-Myc-induced hepatocarcinogenesis, using WHV/c-Myc transgenic mice. Co-expression of cyto-Met and c-Myc further enhanced hepatocyte proliferation and caused a dramatic acceleration of the Myc-induced tumorigenesis, leading to the emergence of hepatocarcinomas in 3-4-month-old animals. Importantly, the TGF-beta receptor type II expression was strongly downregulated in most tumours, indicating that impairment of TGF-beta1-mediated growth inhibition plays a major role in accelerated neoplastic development. The strong potential of cyto-Met for oncogenic cooperation without direct transforming activity designates cyto-Met mice as an ideal tool for studying the early steps of multistage hepatocarcinogenesis and for identification of prognostic markers of transformation.
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MESH Headings
- Animals
- Apoptosis
- Blotting, Western
- Cell Division
- Cell Transformation, Neoplastic
- Down-Regulation
- Gene Expression Regulation, Neoplastic
- Hepatitis B Virus, Woodchuck/genetics
- Hepatocytes/metabolism
- Hepatocytes/pathology
- Homeostasis
- Humans
- Hyperplasia/genetics
- Hyperplasia/metabolism
- Hyperplasia/pathology
- Liver Neoplasms/genetics
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Mice
- Mice, Transgenic
- Organ Size
- Promoter Regions, Genetic/genetics
- Protein Serine-Threonine Kinases
- Proto-Oncogene Proteins c-met/genetics
- Proto-Oncogene Proteins c-met/metabolism
- Proto-Oncogene Proteins c-myc/genetics
- Proto-Oncogene Proteins c-myc/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor, Transforming Growth Factor-beta Type II
- Receptors, Transforming Growth Factor beta/metabolism
- Signal Transduction
- Transforming Growth Factor beta/metabolism
- Transforming Growth Factor beta1
- Transgenes/genetics
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Affiliation(s)
- Laura Amicone
- Fondazione Istituto Pasteur-Cenci Bolognetti, Dipartimento di Biotecnologie Cellulari ed Ematologia, Sezione di Genetica Molecolare, Università La Sapienza, 00161, Rome, Italy
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24
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Merle P, Chevallier M, Levy R, Maisonnas M, Terradillos O, Trépo C, Buendia MA, Vitvitski-Trépo L. Preliminary results of interferon-alpha therapy on woodchuck hepatitis virus-induced hepatocarcinogenesis: possible benefit in female transgenic mice. J Hepatol 2001; 34:562-9. [PMID: 11394656 DOI: 10.1016/s0168-8278(00)00054-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
BACKGROUND C-myc activation is a potent oncogenic event in hepatocarcinogenesis. The aim of this study was to test the preventive effect of interferon-alpha (IFN-alpha) on the development of dysplasia and subsequent hepatocellular carcinoma (HCC) in transgenic (Tg) mice overexpressing c-myc in the liver. METHODS The WHV/c-myc Tg mice recapitulating woodchuck hepatitis virus-induced hepatocarcinogenesis were treated with IFN-alpha, starting early in life until sacrifice at pre-neoplastic or neoplastic stages. Transgene expression was assessed by reverse transcription-polymerase chain reaction (RT-PCR), hepatocyte proliferation was assessed by bromodeoxyuridine incorporation and RT-PCR for proliferating cell nuclear antigen, and apoptosis was assessed by in situ nick-end-labeling of DNA. RESULTS C-myc expression and hepatocyte proliferation were significantly reduced in treated female mice, without modification of apoptosis, correlating with a lower severity of dysplasia in 9/12 treated animals at pre-neoplastic stages. At the neoplastic stage, 2/3 treated females neither exhibited carcinoma nor dysplasia, while all 6/6 untreated mice and 3/3 treated males developed carcinomas. CONCLUSIONS Inhibition of c-myc and hepatocyte proliferation by long-term administration of IFN-alpha was associated with a decrease, or a delay, of oncogenesis in the mouse Tg HCC model. Whether c-myc and hepatocyte proliferation down-regulation could be relevant parameters of IFN-alpha efficiency for hepatocarcinogenesis prevention in cirrhotic patients should be established.
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Affiliation(s)
- P Merle
- INSERM Unit 271, Lyon, France
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25
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26
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Abstract
Hepatocellular carcinoma (HCC) is one of the human cancers clearly linked to viral infections. Although the major viral and environmental risk factors for HCC development have been unravelled, the oncogenic pathways leading to malignant transformation of liver cells have long remained obscure. Recent outcomes have been provided by extensive allelotype studies which resulted in a comprehensive overview of the main genetic abnormalities in HCC, including DNA copy gains and losses. The differential involvement of the p53 tumor-suppressor gene in tumors associated with various risk factors has been largely clarified. Evidence for a crucial role of the reactivation of the Wnt/beta-catenin pathway, through mutations in the beta-catenin and axin genes in 30-40% of liver tumors, represents a major breakthrough. It has also been shown that the Rb pathway is frequently disrupted by methylation-dependent silencing of the p16INK4A gene and stimulation of Rb degradation by a proteosomal subunit. Presently, the identification of candidate oncogenes and tumor suppressors in the most frequently altered chromosomal regions is a major challenge. Great insights will come from integrating the signals from different pathways operating at preneoplastic and neoplastic stages. This search might, in time, permit an accurate evaluation of the major targets for therapeutic treatments.
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Affiliation(s)
- M A Buendia
- Unité INSERM U163, Department of Retroviruses, Institut Pasteur, Paris
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27
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Renard CA, Fourel G, Bralet MP, Degott C, De La Coste A, Perret C, Tiollais P, Buendia MA. Hepatocellular carcinoma in WHV/N-myc2 transgenic mice: oncogenic mutations of beta-catenin and synergistic effect of p53 null alleles. Oncogene 2000; 19:2678-86. [PMID: 10851067 DOI: 10.1038/sj.onc.1203617] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The intronless N-myc2 gene was originally identified as the major target of hepatitis virus insertion in woodchuck liver tumors. Here we report that transgenic mice carrying the N-myc2 gene controlled by woodchuck hepatitis virus (WHV) regulatory sequences are highly predisposed to liver cancer. In a WHV/N-myc2 transgenic line, hepatocellular carcinomas or adenomas arose in over 70% of mice, despite barely detectable expression of the methylated transgene in liver cells. Furthermore, a transgenic founder carrying unmethylated transgene sequences succumbed to a large liver tumor by the age of two months, demonstrating the high oncogenicity of the woodchuck N-myc2 retroposon. Stabilizing mutations or deletions of beta-catenin were found in 25% of liver tumors and correlated with reduced tumor latency (P<0.05), confirming the important role of beta-catenin activation in Myc-induced tumorigenesis. The ability of the tumor suppressor gene p53 to cooperate with N-myc2 in liver cell transformation was tested by introducing a p53-null allele into WHV/N-myc2 transgenic mice. The loss of one p53 allele in transgenic animals markedly accelerated the onset of liver cancer (P=0.0001), and most tumors of WHV/N-myc2 p53+/Delta mice harbored either a deletion of the wt p53 allele or a beta-catenin mutation. These findings provide direct evidence that activation of N-myc2 and reduction of p53 levels act synergistically during multistage carcinogenesis in vivo and suggest that different genetic pathways may underlie liver carcinogenesis initiated by a myc transgene. Oncogene (2000).
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Affiliation(s)
- C A Renard
- Unité de Recombinaison et Expression Génétique (INSERM U163), Institut Pasteur, 28 rue du Dr. Roux, 75015 Paris, France
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28
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Abstract
Wnt/beta-catenin signaling is frequently activated in cancer cells by stabilizing mutations of beta-catenin or loss-of-function mutations of the APC tumor suppressor gene. We have analysed the role of beta-catenin in the pathogenesis of hepatoblastoma (HB), an embryonic liver tumor occurring mainly in children under 2 years of age. Sequence analysis of the beta-catenin NH2-terminal domain in 18 epithelial and mixed HBs revealed missense mutations in the GSK3beta phosphorylation motif or interstitial deletions in 12 tumors (67%). In the remaining cases, no truncating mutation of APC could be evidenced. Immunohistochemical analysis of beta-catenin in 11 HBs demonstrated nuclear/cytoplasmic accumulation of the protein in all tumors analysed, with predominant nuclear beta-catenin immunostaining in undifferentiated cells. Membranous beta-catenin localization was preserved only in fetal-type tumoral hepatocytes and was associated with E-cadherin expression. Moreover, we show that beta-catenin is aberrantly overexpressed in a large spectrum of tumor components, including hepatocyte-like cells at various differentiation stages and heterologous elements such as squamous, osteoid and chrondroid tissues, and in occasional other mesenchymally-derived cells. These data strongly suggest that activation of beta-catenin signaling is an obligatory step in HB pathogenesis, and raise the possibility that it interferes with developmental signals that specify different tissue types at early stages of hepatic differentiation.
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Affiliation(s)
- Y Wei
- Unité de Recombinasion et Expression Génétique INSERM U163, Institut Pasteur, Paris, France
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29
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Nhieu JT, Renard CA, Wei Y, Cherqui D, Zafrani ES, Buendia MA. Nuclear accumulation of mutated beta-catenin in hepatocellular carcinoma is associated with increased cell proliferation. Am J Pathol 1999; 155:703-10. [PMID: 10487827 PMCID: PMC1866892 DOI: 10.1016/s0002-9440(10)65168-1] [Citation(s) in RCA: 242] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Inappropriate activation of the Wnt pathway resulting from beta-catenin gene alterations has recently been implicated in the development of hepatocellular carcinoma (HCC). To explore the in vivo effects of mutated beta-catenin, HCC specimens from 32 patients carrying one or several tumors were screened for somatic mutations in exon 3 of the beta-catenin gene, and the expression and subcellular localization of beta-catenin was studied by immunohistochemistry. Missense mutations or interstitial deletions in beta-catenin exon 3 were detected in 12 of 35 (34%) HCC samples. After immunostaining, most tumors exhibited increased membranous and/or cytoplasmic expression of beta-catenin compared with adjacent nontumoral liver. Strong nuclear accumulation of beta-catenin was observed either focally or uniformly in 15 of 35 (43%) tumor specimens, but not in cirrhotic nodules or dysplastic liver cells in adjacent liver. Aberrant nuclear expression of beta-catenin was significantly associated with the presence of mutations in the beta-catenin gene (P < 0.005). Moreover, nuclear beta-catenin staining correlated significantly with increased Ki-67 proliferative index in tumor (P < 0.001) and seemed to be associated with poor outcome in patients with HCC. In conclusion, our data indicate that activation of the Wnt/beta-catenin pathway in HCC results mainly from somatic mutations in the beta-catenin gene and may promote tumor progression by stimulating tumor cell proliferation.
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Affiliation(s)
- J T Nhieu
- Département de Pathologie, Service de Chirurgie, Hôpital Henri Mondor - AP-HP, Créteil, Paris, France
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30
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Pineau P, Nagai H, Prigent S, Wei Y, Gyapay G, Weissenbach J, Tiollais P, Buendia MA, Dejean A. Identification of three distinct regions of allelic deletions on the short arm of chromosome 8 in hepatocellular carcinoma. Oncogene 1999; 18:3127-34. [PMID: 10340384 DOI: 10.1038/sj.onc.1202648] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The chromosome 8p is associated with a large number of allelic imbalances in epithelial tumors including hepatocellular carcinoma (HCC). However, no tumor suppressor gene has been identified so far in this particular region of the genome. To further clarify the pattern of allelic deletions on chromosome 8p in HCC, we have undertaken high-density polymorphic marker analysis of 109 paired normal and primary tumor samples using 40 microsatellites positioned every 2 cm in average throughout 8p. We found that 60% of the tumors exhibited loss of heterozygosity (LOH) at one or more loci at 8p with three distinct minimal deleted areas: a 13 cm region in the distal part of 8p21, a 9 cm area in the more proximal portion of 8p22 and a 5 cm area in 8p23. These data strongly suggest the presence of at least three novel tumor suppressor loci on 8p in hepatocellular carcinoma.
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Affiliation(s)
- P Pineau
- Unité de Recombinaison & Expression Génétique, INSERM U163, Institut Pasteur, Paris, France
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31
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Abstract
The hepatitis B virus (HBV) is a common human pathogen that causes acute and chronic liver disease. Persistent HBV infection is strongly associated with the development of hepatocellular carcinoma. The contribution of the viral regulatory protein HBx in liver oncogenesis has been supported by our recent studies in a transgenic mouse model, showing that HBx cooperates with c-myc by accelerating the onset of primary liver tumors. Here we show that liver expression of HBx is associated with increased rates of spontaneous apoptosis in liver cells from two different transgenic lines. In transient transfection assays, overexpression of HBx in the established hepatocyte cell line MMHD3 and in human hepatoma cells HepG2 was found to induce apoptosis in a dose-dependent manner. These data suggest that HBx might trigger an apoptotic process in HBV-infected hepatocytes, in turn possibly favoring liver regeneration and accumulation of genetic alterations, ultimately leading to liver cell transformation in chronically infected patients.
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Affiliation(s)
- T Pollicino
- Département du SIDA et des Rétrovirus, Institut Pasteur, Paris, France
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32
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Terradillos O, Pollicino T, Lecoeur H, Tripodi M, Gougeon ML, Tiollais P, Buendia MA. p53-independent apoptotic effects of the hepatitis B virus HBx protein in vivo and in vitro. Oncogene 1998; 17:2115-23. [PMID: 9798683 DOI: 10.1038/sj.onc.1202432] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The hepatitis B virus protein HBx is a promiscuous transactivator implicated in both cell growth and death and in the development of hepatocellular carcinoma. We recently reported that HBx can potentiate c-myc-induced liver oncogenesis in a transgenic model where low level expression of HBx induces no pathology. To assess if HBx could affect the hepatocyte turnover, we investigated the HBx-elicited apoptotic responses in transgenic livers and in primary hepatocyte cultures. Here we show that transgenic expression of HBx is associated with a twofold increase of spontaneous cell death in the mouse liver. The finding that apoptosis was enhanced to similar extents in HBx mice carrying homozygous p53 null mutations implied that functionally intact p53 was not required to transduce the death signal. A direct, dose-dependent apoptotic function of HBx was demonstrated in transient transfections of liver-derived cell lines. We further show that stable expression of HBx at low, presumably physiological levels in primary hepatocytes, induced cellular susceptibility to diverse apoptotic insults, including growth factor deprivation, treatment with anti-Fas antibodies or doxorubicine and oxidative stress. HBx expression, but not p53 status profoundly affected the commitment of cells to die upon apoptotic stimuli. These data strengthen the notion that HBX may contribute to HBV pathogenesis by enhancing apoptotic death in the chronically infected liver.
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Affiliation(s)
- O Terradillos
- Unité de Recombinaison et Expression Génétique (INSERM U163), Paris, France
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33
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Abstract
Hepatitis B virus (HBV) is a small, enveloped DNA virus which primarily infects liver cells and causes acute and persistent liver disease. Chronic HBV infection, frequently associated with cirrhosis and eventually hepatocellular carcinoma (HCC), represents a major health problem in the world. HBV is the prototype member of the hepadnavirus family, which includes several related mammalian viruses also implicated in liver carcinogenesis in the host. Although epidemiological evidence has clearly linked HBV infection with HCC development, the precise role of the virus and the molecular mechanisms of liver cell transformation remain elusive. Here we discuss potential oncogenic strategies of HBV, ranging from indirect mechanisms related to chronic necroinflammatory disease and to the effects of viral gene products on cell proliferation and apoptosis, to direct insertional activation of cellular (onco)genes. Presently, vaccination of high risk populations represents a major way to prevent the development of HBV-related liver cancer.
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Affiliation(s)
- M A Buendia
- Unité de Recombinaison et Expression Génétique, INSERM U163, Institut Pasteur, Paris, France
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34
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de La Coste A, Romagnolo B, Billuart P, Renard CA, Buendia MA, Soubrane O, Fabre M, Chelly J, Beldjord C, Kahn A, Perret C. Somatic mutations of the beta-catenin gene are frequent in mouse and human hepatocellular carcinomas. Proc Natl Acad Sci U S A 1998; 95:8847-51. [PMID: 9671767 PMCID: PMC21165 DOI: 10.1073/pnas.95.15.8847] [Citation(s) in RCA: 822] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is the major primary malignant tumor in the human liver, but the molecular changes leading to liver cell transformation remain largely unknown. The Wnt-beta-catenin pathway is activated in colon cancers and some melanoma cell lines, but has not yet been investigated in HCC. We have examined the status of the beta-catenin gene in different transgenic mouse lines of HCC obtained with the oncogenes c-myc or H-ras. Fifty percent of the hepatic tumors in these transgenic mice had activating somatic mutations within the beta-catenin gene similar to those found in colon cancers and melanomas. These alterations in the beta-catenin gene (point mutations or deletions) lead to a disregulation of the signaling function of beta-catenin and thus to carcinogenesis. We then analyzed human HCCs and found similar mutations in eight of 31 (26%) human liver tumors tested and in HepG2 and HuH6 hepatoma cells. The mutations led to the accumulation of beta-catenin in the nucleus. Thus alterations in the beta-catenin gene frequently are selected for during liver tumorigenesis and suggest that disregulation of the Wnt-beta-catenin pathway is a major event in the development of HCC in humans and mice.
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Affiliation(s)
- A de La Coste
- Institut National de la Santé et de la Recherche Médicale U129, Institut Cochin de Génétique Moléculaire, Université Paris V René Descartes, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France
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35
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Flajolet M, Tiollais P, Buendia MA, Fourel G. Woodchuck hepatitis virus enhancer I and enhancer II are both involved in N-myc2 activation in woodchuck liver tumors. J Virol 1998; 72:6175-80. [PMID: 9621085 PMCID: PMC110429 DOI: 10.1128/jvi.72.7.6175-6180.1998] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/1997] [Accepted: 03/25/1998] [Indexed: 02/07/2023] Open
Abstract
Direct activation of the N-myc2 oncogene by insertion of woodchuck hepatitis virus (WHV) DNA is a major oncogenic step in woodchuck hepatocarcinogenesis. We previously reported that WHV enhancer II (We2), which controls expression of the core/pregenome RNA, can also activate the N-myc2 promoter in hepatoma cell lines. To better define the integrated WHV regulatory sequences responsible for N-myc2 promoter activation in woodchuck liver tumors, we analyzed the structure and enhancer activity of a single viral integrant found at the win locus in tumor 2260T1 and mapping approximately 175 kb 3' of N-myc2. This viral insert was made of 11 concatemerized WHV fragments, 5 of which overlapped with We2 sequences and 1 with WHV sequence homologous to that of hepatitis B virus enhancer I (We1). In transient transfection assays in hepatoma-derived cells, the We2 activator was found to be fully effective only when inserted in close proximity to the N-myc2 promoter whereas the We1 element by itself was apparently devoid of activity. In contrast, the 2260T1 viral insert exhibited a potent enhancer capacity that depended both on multimerized We2 and on We1 sequences. In a survey of different woodchuck hepatomas, both elements were commonly found within integrated viral sequences involved in long-range N-myc2 activation.
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Affiliation(s)
- M Flajolet
- Unité de Recombinaison et Expression Génétique, INSERM U163, Institut Pasteur, 75724 Paris Cedex 15, France
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36
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Tiollais P, Pineau P, Wei Y, Dejean A, Buendia MA. [Hepatitis B virus and hepatocellular carcinoma]. Bull Acad Natl Med 1998; 182:73-7; discussion 77-8. [PMID: 9622933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatitis B is a very important public health problem. Epidemiologic studies have shown a relationship between the hepatitis B virus (HBV) chronic carrier state and the development of hepatocellular carcinoma. HBV belongs to the Hepadna viruses family which includes the woodchuck hepatitis virus (WHV), Woodchucks infected with WHV represent a good experimental model to study the viral oncogenesis. In 85% of the studied cases, WHV acts by insertional mutagenesis in a gene of the myc family, mostly the N-myc2 gene. Expression of the myc genes is increased, suggesting the role of the viral enhancer. Study of transgenic mice have shown the liver specificity of the WHV action. In man, the liver oncogenesis is not explained. Studies are in progress to detect inactivation of tumor suppressor genes.
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Affiliation(s)
- P Tiollais
- Unité de Recombinaison et Expression Génétique (INSERM U.163), Institut Pasteur, Paris
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37
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Renard CA, Transy C, Tiollais P, Buendia MA. Infection of WHV/c-myc transgenic mice with Moloney murine leukaemia virus and proviral insertion near the syndecan-4 gene in an early liver tumour. Res Virol 1998; 149:133-43. [PMID: 9711537 DOI: 10.1016/s0923-2516(98)80031-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The capacity of Moloney murine leukaemia virus (MoMLV) to infect neonatal hepatocytes and to accelerate liver carcinogenesis was examined in a transgenic mouse model. WHV/c-myc mice which are highly susceptible to the development of liver tumours were infected with MoMLV shortly after birth, when expression of the murine ecotropic retroviral receptor gene was still detectable in the neonatal liver. All MoMLV-infected transgenic mice and non-transgenic littermates succumbed to T-cell lymphomas within 2-9 months; during this period of time, three infected transgenic animals developed primary hepatocellular carcinomas. Remarkably, one of these liver tumours arose significantly faster than tumours from uninfected WHV/c-myc controls, and it harboured a unique MoMLV provirus. The provirus integration site was located 5.5 kb upstream of the first exon of the syndecan-4 gene, which encodes a heparan sulphate proteoglycan implicated in growth factor activation and protein kinase C distribution in focal adhesions. Our data provide evidence for clonal MoMLV provirus integration in a hepatocellular carcinoma, and indicate that parenchymal liver cells may be susceptible to MoMLV infection following neonatal inoculation.
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Affiliation(s)
- C A Renard
- Unité de Recombinaison et Expression génétique (INSERM U.163), Institut Pasteur, Paris
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38
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Fourel G, Ringeisen F, Flajolet M, Tiollais P, Buendia MA. Functional analysis of ground squirrel hepatitis virus enhancer II. J Virol 1998; 72:1616-22. [PMID: 9445066 PMCID: PMC124644 DOI: 10.1128/jvi.72.2.1616-1622.1998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/1997] [Accepted: 10/15/1997] [Indexed: 02/05/2023] Open
Abstract
We have characterized a major regulatory element of ground squirrel hepatitis virus (GSHV) located within a 90-nucleotide fragment of the core promoter upstream sequences and have compared its organization to that of woodchuck hepatitis virus (WHV) enhancer II (We2). The GSHV element (Ge2) stimulates transcription from the viral core promoter and heterologous promoters in an orientation-independent manner but displays a lower level of activity than We2 in transient transfection assays in human hepatoma cells. The general organization of Ge2 into binding sites for the liver-enriched HNF-1 and HNF-4 proteins and for ubiquitous factors of the NF1 and Oct families was found to be mostly conserved with respect to the homologous We2 region. Accordingly, transactivation by HNF-1 and HNF-4 plays an essential role in the liver-specific transcriptional activity of both the GSHV and WHV core promoters. Distinctive features of the GSHV enhancer consist of its ability to bind C/EBP family factors in a central motif that overlaps with one of the two HNF-4 sites and its differential binding affinities for HNF-4.
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Affiliation(s)
- G Fourel
- Unité de Recombinaison et Expression Génétique, INSERM U163, Institut Pasteur, Paris, France
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39
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Merle P, Levy R, Vitvitski L, Chevallier M, Buendia MA, Trepo C. [Efficacy of interferon alpha in primary prevention of preneoplastic lesions in a transgenic murine model of hepatocellular carcinoma related to the interaction between woodchuck hepatitis viruses and c-myc oncogene]. Gastroenterol Clin Biol 1997; 21:459-65. [PMID: 9295972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES C-myc oncogene overexpression by near insertion of hepatitis B virus is important in woodchuck hepatocarcinogenesis. This DNA fragment was transferred in mice who developed hepatocellular carcinoma via preneoplastic lesions. In the present study, we tested the preventive effect of alpha interferon on the incidence of hepatocyte dysplasia. METHODS Human recombinant alpha interferon hybrid B/D was continuously administered at increasing doses (0 to 10,000 IU/g) in a transgenic mouse model. One cohort was treated from day 21 to day 80. A histological liver examination was performed and the transgene expression was assessed by hybridization with or without previous genic amplification, and by indirect immunofluorescence. RESULTS At day 15, histological liver examination was normal. Interferon treatment decreased the expression of viral sequences, but not of c-myc. At day 80, interferon treatment resulted in a reduction of the incidence and severity of dysplasic lesions, and a marked decrease in c-myc overexpression. CONCLUSION In this transgenic mouse model, alpha interferon treatment decreased the incidence and severity of precancerous lesions, due to a reduction in c-myc overexpression. This prophylaxis could be of interest in human hepatocarcinogenesis where c-myc overexpression is frequent.
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Affiliation(s)
- P Merle
- Laboratoire de Recherche sur les Hépatites et les Rétrovirus Humains, INSERM U271, Lyon
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40
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Flajolet M, Gegonne A, Ghysdael J, Tiollais P, Buendia MA, Fourel G. Cellular and viral trans-acting factors modulate N-myc2 promoter activity in woodchuck liver tumors. Oncogene 1997; 15:1103-10. [PMID: 9285565 DOI: 10.1038/sj.onc.1201257] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Activation of the N-myc2 oncogene by integration of woodchuck hepatitis virus (WHV) DNA is a central event in woodchuck liver oncogenesis. In this study, we have evaluated the influence of several cellular and viral trans-acting factors and mediators of inflammation on N-myc2 promoter activity in hepatoma cell lines. Ets oncoproteins, including Ets1, Ets2 and PEA3 efficiently activated a chimeric N-myc2 promoter/luciferase reporter gene. By electrophoretic mobility shift assays, we show that Etsl and Ets2 proteins can efficiently bind two consensus Ets sites located within a 59 bp sequence upstream of the N-myc2 transcription start site. Site-directed mutagenesis of these Ets-binding motifs abolished transactivation of the N-myc2 promoter by Ets proteins. Addition of interleukin-6 (IL-6) induced a weak but reproducible activation of the N-myc2 promoter, while IL-1 was ineffective. We further show that the N-myc2 promoter can be transactivated by the hepadna-virus X protein, and that distal promoter sequences are required for both IL-6 and X responsiveness. Similar effects of these factors were observed in the context of the N-myc2 promoter activated by WHV cis-regulatory elements. In view of the high-level expression of the N-myc2 oncogene in most woodchuck liver tumors, the Ets oncoproteins, inflammation-associated cytokine IL-6 and the viral X transactivator might play important roles in hepadnavirus-associated tumorigenesis.
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Affiliation(s)
- M Flajolet
- Unité de Recombinaison et Expression Génétique (INSERM U163), Institut Pasteur, Paris, France
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41
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Abstract
Hepatocellular carcinoma (HCC) is one of the most common cancers in many parts of the world, however the molecular mechanisms underlying liver cell transformation remain obscure. A genome-wide scan of loss of heterozygosity (LOH) in tumors provides a powerful tool to search for genes involved in neoplastic processes. To identify recurrent genetic alterations in liver tumors, we examined DNAs isolated from 120 HCCs and their adjacent non tumorous parts for LOH using a collection of 195 microsatellite markers located roughly every 20 cM throughout 39 autosomal arms. The mean heterozygosity was 73%. Our findings provide additional support that LOH for loci on chromosomal arms 1p, 4q, 6q, 8p, 13q and 16p is significantly elevated in HCC. The highest percentage of LOH is found for a locus in 8p23 (42% of informative csaes). This corresponds to one of the most common genetic abnormalities reported to date in these tumors. In addition, high ratio of LOH (> or = 35%) is observed on chromosome arms which had not been implicated in previous studies, notably on 1q, 2q and 9q. No correlation was found between LOH of specific chromosomal regions and etiologic factors such as chronic infections with hepatitis B or C viruses. This first report of an extensive allelotypic analysis of HCC should help in identifying new genes whose loss of function contributes to the development of liver cancer.
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Affiliation(s)
- H Nagai
- Unité de Recombinaison et Expression Génétique, INSERM U163, Institut Pasteur, Paris, France
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42
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Liu P, Terradillos O, Renard CA, Feldmann G, Buendia MA, Bernuau D. Hepatocarcinogenesis in woodchuck hepatitis virus/c-myc mice: sustained cell proliferation and biphasic activation of insulin-like growth factor II. Hepatology 1997; 25:874-83. [PMID: 9096591 DOI: 10.1002/hep.510250415] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Transgenic mice carrying the c-myc oncogene under control of woodchuck hepatitis virus (WHV) DNA sequences invariably develop hepatocellular carcinoma (HCC), despite a temporally limited expression of the transgene in the neonatal liver. To better characterize the different steps of the tumorigenic process, we analyzed the liver expression of the c-myc transgene and several growth-related genes by in situ hybridization and Northern blotting. In parallel studies, proliferated changes were investigated by detection of bromodeoxy-uridine-positive S-phase nuclei and apoptosis was evaluated by in situ nick end-labeling of DNA. During the neonatal period, high levels of c-myc messenger RNAs (mRNAs) were detected in all hepatocytes, and the expression of insulin-like growth factor II (IGF II) was frequently enhanced, correlating with increased cell proliferation. Despite elevated expression of the p53 gene, no change in liver cell apoptosis was observed. After weaning, c-myc transgene expression decreased to undetectable levels in all hepatocytes, whereas proliferation decreased but remained notably higher than in age-matched controls. The expression of c-fos, c-jun, and c-H-ras was highly variable during the preneoplastic period and in the tumors, with no consistent increase compared with controls. Resurgence of c-myc transgene expression was evidenced in all cells from hyperplastic lesions and carcinomas, accompanied with frequent focal reactivation of IGF II. Thus the strong proliferative stimulus induced by the combined effects of c-myc and IGF II in the neonatal liver might initiate a process characterized by persistent, dysregulated hepatocyte proliferation, in turn greatly increasing the risk of hepatocellular transformation.
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MESH Headings
- Animals
- Cell Division
- Gene Expression Regulation, Neoplastic
- Genes, fos
- Genes, jun
- Genes, myc
- Genes, p53
- Genes, ras
- Hepatitis B Virus, Woodchuck/genetics
- Hepatitis B Virus, Woodchuck/pathogenicity
- In Situ Hybridization
- Insulin-Like Growth Factor II/genetics
- Liver Neoplasms, Experimental/etiology
- Liver Neoplasms, Experimental/metabolism
- Liver Neoplasms, Experimental/pathology
- Mice
- Mice, Transgenic
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Neoplasm/genetics
- RNA, Neoplasm/metabolism
- Transforming Growth Factor alpha/genetics
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Affiliation(s)
- P Liu
- Laboratoire de Biologie Cellulaire, INSERM U 327, Faculté de Médecine X. Bichat, Paris, France
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43
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Terradillos O, Billet O, Renard CA, Levy R, Molina T, Briand P, Buendia MA. The hepatitis B virus X gene potentiates c-myc-induced liver oncogenesis in transgenic mice. Oncogene 1997; 14:395-404. [PMID: 9053836 DOI: 10.1038/sj.onc.1200850] [Citation(s) in RCA: 225] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The hepatitis B virus X protein (HBx) is thought to be implicated in the development of hepatocellular carcinoma, but its exact function remains controversial. Transgenic mice from PEX7 and AX16 lineages that express HBx in the liver under control of different viral regulatory elements develop no liver pathology (Billet et al., 1995). We have crossed these two mouse lineages with WHV/c-myc oncomice in which liver-specific expression of c-myc driven by woodchuck hepatitis virus (WHV) regulatory sequences causes liver cancer in all animals. The average tumor latency was shortened by 2 to 3 months in bitransgenic animals from all populations compared with simple c-myc transgenic littermates. At preneoplastic stages, adult bitransgenic mice showed four to fivefold enhanced expression of the c-myc transgene, increased hepatocyte proliferation and more extensive liver lesions compared with simple WHV/c-myc transgenics. Thus in this model, HBx alone has no direct pathological effect but it is shown to accelerate tumor development induced by c-myc. The data presented here firmly establish the oncogenic potential of HBx, apparently acting as a tumor promoter. This model offers unique opportunities to investigate the mechanisms by which HBx trans-activates the expression of target genes and deregulates the hepatocyte growth control in vivo.
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Affiliation(s)
- O Terradillos
- Unité de Recombinaison et Expression Génétique (INSERM U163), Institut Pasteur, Paris, France
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44
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Fourel G, Ringeisen F, Flajolet M, Tronche F, Pontoglio M, Tiollais P, Buendia MA. The HNF1/HNF4-dependent We2 element of woodchuck hepatitis virus controls viral replication and can activate the N-myc2 promoter. J Virol 1996; 70:8571-83. [PMID: 8970982 PMCID: PMC190950 DOI: 10.1128/jvi.70.12.8571-8583.1996] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Transcriptional activation of myc family proto-oncogenes through the insertion of viral sequences is the predominant mechanism by which woodchuck hepatitis virus (WHV) induces liver tumors in chronically infected animals. The main target is N-myc2, a functional retroposon of the N-myc gene, but c-myc and N-myc are also marginally involved. Here we identify a major, liver-specific regulatory element in the WHV genome (We2) which efficiently activates the N-myc2 promoter in cultured hepatoma cells. In the context of the episomal viral genome, We2 governs the production of pregenomic RNA and thus plays a central role in the control of viral replication. We2 activity is primarily controlled by the liver-enriched HNF1 and HNF4 transcription factors, although NF1 and Oct proteins were also shown to bind in a central region. The expression of HNF1 and HNF4 appears to be maintained in woodchuck tumors. Thus, We2 is a prime candidate for controlling myc gene cis activation during WHV-induced hepatocarcinogenesis.
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Affiliation(s)
- G Fourel
- Unité de Recombinaison et Expression Génétique, INSERM U163, Institut Pasteur, Paris, France
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45
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Testut P, Renard CA, Terradillos O, Vitvitski-Trepo L, Tekaia F, Degott C, Blake J, Boyer B, Buendia MA. A new hepadnavirus endemic in arctic ground squirrels in Alaska. J Virol 1996; 70:4210-9. [PMID: 8676441 PMCID: PMC190351 DOI: 10.1128/jvi.70.7.4210-4219.1996] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We present evidence for a novel member of the hepadnavirus family that is endemic in wild arctic ground squirrels (Spermophylus parryi kennicotti) in Alaska. This virus, designated arctic squirrel hepatitis virus (ASHV), was initially detected in the livers of animals bearing large hepatic nodules by nucleic acid hybridization with hepadnavirus probes and in plasma by cross-reactivity with antibodies to hepadnavirus surface and core antigens. The complete nucleotide sequence of the 3,302-bp-long ASHV genome was determined and compared with those of ground squirrel hepatitis virus (GSHV) and woodchuck hepatitis virus (WHV); all sequences were organized into four open reading frames, designated pre-C/C, pre-S/S, pol, and X. Despite roughly equivalent variability among the three rodent hepadnaviruses (around 16% base and 19% amino acid exchanges), ASHV appeared to be more closely related to GSHV than to WHV in phylogenetic analysis. Accordingly, preliminary studies of the pathology of ASHV infection suggested that ASHV may be a less efficient oncogenic agent than WHV. About one-third of aged animals maintained in captivity, including virus-infected as well as uninfected squirrels, developed large liver nodules, consisting of hepatocellular adenomas or carcinomas or nonmalignant lesions characterized by drastic microvesicular steatosis. ASHV-infected arctic ground squirrels may serve as a new model with which to analyze the contribution of hepadnavirus- and host-specific determinants to liver pathology and tumorigenesis.
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MESH Headings
- Alaska
- Amino Acid Sequence
- Animals
- Base Sequence
- DNA, Viral
- Genome, Viral
- Hepatitis B Virus, Woodchuck/genetics
- Hepatitis, Viral, Animal/blood
- Hepatitis, Viral, Animal/pathology
- Hepatitis, Viral, Animal/virology
- Liver/pathology
- Liver/virology
- Liver Neoplasms/virology
- Molecular Sequence Data
- Orthohepadnavirus/classification
- Orthohepadnavirus/genetics
- Orthohepadnavirus/metabolism
- Phylogeny
- Sciuridae/virology
- Sequence Homology, Amino Acid
- Viral Proteins/metabolism
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Affiliation(s)
- P Testut
- Unité de Recombinaison et Expression Génétique (INSERM U163), France
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46
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Quignon F, Renard CA, Tiollais P, Buendia MA, Transy C. A functional N-myc2 retroposon in ground squirrels: implications for hepadnavirus-associated carcinogenesis. Oncogene 1996; 12:2011-7. [PMID: 8649862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Three hepatitis B viruses infecting humans, woodchucks and ground squirrels increase the risk of hepatocellular carcinoma in their respective hosts. The woodchuck hepatitis B virus (WHV), unlike the two other viruses, induces a rapid carcinogenic process characterized by direct activation of myc proto-oncogenes by insertion of viral DNA. The highly preferred target of insertional mutagenesis in woodchucks is N-myc2, an intronless N-myc gene. Strikingly, N-myc2 has no human homolog and the homologous N-myc2 locus previously detected in the ground squirrel genome, remains silent during hepatocarcinogenesis. Therefore, N-myc2 may represent a critical host determinant in the evolution of the disease associated with hepadnavirus infection. To address this question, we performed a structural and functional analysis of the ground squirrel N-myc2 locus. We show that ground squirrel N-myc2 is highly homologous to its woodchuck counterpart and is a functional proto-oncogene. Existence of a functional N-myc2 gene as a potential target for insertional activation by viral DNA is therefore not restricted to the woodchuck species. This suggests that viral rather than host factors determine the higher oncogenic phenotype of WHV as compared to the two other mammalian hepadnaviruses.
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Affiliation(s)
- F Quignon
- Unité de Recombinaison et Expression Génétique (INSERM U163), Institut Pasteur, Paris, France
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Wei Y, Etiemble J, Renard CA, Tiollais P, Buendia MA. Unusual activation of the integrated preS1 promoter of woodchuck hepatitis virus in a liver tumour. J Gen Virol 1996; 77 ( Pt 2 ):177-82. [PMID: 8627220 DOI: 10.1099/0022-1317-77-2-177] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have analysed abnormal virus RNAs produced from integrated woodchuck hepatitis virus (WHV) sequences in two woodchuck liver tumours. Analysis of cDNA clones revealed that these transcripts consisted of rearranged, virus-specific RNAs encoding the WHV surface antigens. In one tumour, transcription was driven by the major preS2/S promoter and terminated at a cryptic poly(A) signal in the 5' end of the P gene, giving rise to a truncated version of the normal viral S message. In contrast, the integrated preS2/S promoter remained silent in the second tumour. The start sites of two abundant WHV transcripts encoding the large and middle surface proteins were localized about 100 bp upstream and 300 bp downstream of the preS1 translation initiation codon, corresponding to minor start sites of the normal surface protein mRNAs in chronically infected liver. Thus, the preS1 promoter, a weak promoter in episomal replicative forms of the virus, was activated in the integrated state in this tumour. Our results indicate that alternative usage of the preS1 or the preS2/S promoter in the integrated state may yield differential production of the three virus surface proteins in woodchuck liver tumours.
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Affiliation(s)
- Y Wei
- Unité de Recombinaison et Expression Génétique, INSERM U163, Institut Pasteur, Paris, France
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48
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Wei Y, Etiemble J, Fourel G, Vitvitski-Trepo L, Buendia MA. Hepadna virus integration generates virus-cell cotranscripts carrying 3' truncated X genes in human and woodchuck liver tumors. J Med Virol 1995; 45:82-90. [PMID: 7714496 DOI: 10.1002/jmv.1890450116] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Integration of the human and woodchuck hepatitis B viruses (HBV and WHV) in host chromosomes has been implicated in the development of hepatocellular carcinoma by different cis- and trans-acting mechanisms. The structure and coding capacity of abundant HBV and WHV transcripts of abnormal sizes produced from integrated viral sequences in one human and two woodchuck liver tumors were examined. Analysis of cDNA clones revealed in all cases hybrid virus-cell transcripts containing sequences of the viral surface gene, the viral enhancer, and different truncated versions of the viral X transactivator. Cotranscribed cellular sequences showing no significant coding function provided the signals for transcription termination. In two transcripts, the HBX and WHX genes truncated at carboxy terminal positions conserved transcriptional trans-acting capacity in transient transfection assays. These results lend support to the hypothesis that the integrated hepadnavirus X transactivator might participate in the development of woodchuck as well as human liver tumors by a common trans-acting mechanism.
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MESH Headings
- Amino Acid Sequence
- Animals
- Carcinoma, Hepatocellular/virology
- Gene Library
- Genes, Regulator/genetics
- Hepatitis B Virus, Woodchuck/genetics
- Hepatitis B virus/genetics
- Humans
- Liver Neoplasms/virology
- Marmota
- Molecular Sequence Data
- RNA, Messenger/analysis
- RNA, Messenger/genetics
- RNA, Neoplasm/analysis
- RNA, Neoplasm/genetics
- RNA, Viral/analysis
- RNA, Viral/genetics
- Restriction Mapping
- Trans-Activators/genetics
- Transcription, Genetic/genetics
- Transcriptional Activation/genetics
- Viral Regulatory and Accessory Proteins
- Virus Integration
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Affiliation(s)
- Y Wei
- Unité de Recombinaison et Expression Génétique, INSERM U.163, Institut Pasteur, Paris, France
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50
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Abstract
We cloned the integrated ground squirrel hepatitis B virus (GSHV) sequences from two hepatomas showing a single viral insertion. The GSHV inserts shared structural features with integrated DNAs of other hepadnaviruses. Insertional activation of a cellular gene appears unlikely: the integrated GSHV sequences lacked the known viral enhancers and were not expressed in the tumors, and we found no evidence for the presence of a gene at the integration site. Our results, together with those earlier studies, suggest that GSHV does not behave as an extensive insertional mutagen, in sharp contrast with the closely related woodchuck hepatitis virus. GSHV may thus cause carcinogenesis by more indirect mechanisms, as does the human hepatitis B virus.
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Affiliation(s)
- C Transy
- Département des Rétrovirus, Unité de Recombinaison et Expression Génétique (Institut National de la Santé et de la Recherche Médicale U163), Institut Pasteur, Paris, France
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