1
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Turnham RE, Pitea A, Jang GM, Xu Z, Lim HC, Choi AL, Von Dollen J, Levin RS, Webber JT, McCarthy E, Hu J, Li X, Che L, Singh A, Yoon A, Chan G, Kelley RK, Swaney DL, Zhang W, Bandyopadhyay S, Theis FJ, Eckhardt M, Chen X, Shokat KM, Ideker T, Krogan NJ, Gordan JD. HBV Remodels PP2A Complexes to Rewire Kinase Signaling in Hepatocellular Carcinoma. Cancer Res 2025; 85:660-674. [PMID: 39652575 PMCID: PMC11949624 DOI: 10.1158/0008-5472.can-24-0456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 09/09/2024] [Accepted: 12/04/2024] [Indexed: 02/18/2025]
Abstract
Hepatitis B virus (HBV) infections promote liver cancer initiation by inducing inflammation and cellular stress. Despite a primarily indirect effect on oncogenesis, HBV is associated with a recurrent genomic phenotype in hepatocellular carcinoma (HCC), suggesting that it impacts the biology of established HCC. Characterization of the interaction of HBV with host proteins and the mechanistic contributions of HBV to HCC initiation and maintenance could provide insights into HCC biology and uncover therapeutic vulnerabilities. In this study, we used affinity purification mass spectrometry to comprehensively map a network of 145 physical interactions between HBV and human proteins in HCC. A subset of the host factors targeted by HBV proteins were preferentially mutated in non-HBV-associated HCC, suggesting that their interaction with HBV influences HCC biology. HBV interacted with proteins involved in mRNA splicing, mitogenic signaling, and DNA repair, with the latter set interacting with the HBV oncoprotein X (HBx). HBx remodeled the PP2A phosphatase complex by excluding striatin regulatory subunits from the PP2A holoenzyme, and the HBx effects on PP2A caused Hippo kinase activation. In parallel, HBx activated mTOR complex 2, which can prevent YAP degradation. mTOR complex 2-mediated upregulation of YAP was observed in human HCC specimens and mouse HCC models and could be targeted with mTOR kinase inhibitors. Thus, HBV interaction with host proteins rewires HCC signaling rather than directly activating mitogenic pathways, providing an alternative paradigm for the cellular effects of a tumor-promoting virus. Significance: Integrative proteomic and genomic analysis of HBV/host interactions illuminated modifiers of hepatocellular carcinoma behavior and key signaling mechanisms in advanced disease, which suggested that HBV may have therapeutically actionable effects.
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Affiliation(s)
- Rigney E Turnham
- Division of Hematology/Oncology, University of California, San Francisco CA
- Quantitative Biosciences Institute, University of California, San Francisco CA
| | - Adriana Pitea
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Gwendolyn M Jang
- Quantitative Biosciences Institute, University of California, San Francisco CA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco CA
| | - Zhong Xu
- Department of Bioengineering, University of California, San Francisco CA
| | - Huat Chye Lim
- Division of Hematology/Oncology, University of California, San Francisco CA
- Quantitative Biosciences Institute, University of California, San Francisco CA
| | - Alex L Choi
- Division of Hematology/Oncology, University of California, San Francisco CA
- Quantitative Biosciences Institute, University of California, San Francisco CA
| | - John Von Dollen
- Quantitative Biosciences Institute, University of California, San Francisco CA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco CA
| | - Rebecca S. Levin
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco CA
| | - James T Webber
- Department of Bioengineering, University of California, San Francisco CA
| | - Elizabeth McCarthy
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco CA
| | - Junjie Hu
- Department of Bioengineering, University of California, San Francisco CA
| | - Xiaolei Li
- Department of Bioengineering, University of California, San Francisco CA
| | - Li Che
- Department of Bioengineering, University of California, San Francisco CA
| | - Ananya Singh
- Division of Hematology/Oncology, University of California, San Francisco CA
- Quantitative Biosciences Institute, University of California, San Francisco CA
| | - Alex Yoon
- Division of Hematology/Oncology, University of California, San Francisco CA
- Quantitative Biosciences Institute, University of California, San Francisco CA
| | - Gary Chan
- Division of Hematology/Oncology, University of California, San Francisco CA
- Quantitative Biosciences Institute, University of California, San Francisco CA
| | - Robin K Kelley
- Division of Hematology/Oncology, University of California, San Francisco CA
| | - Danielle L Swaney
- Quantitative Biosciences Institute, University of California, San Francisco CA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco CA
| | - Wei Zhang
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | | | - Fabian J Theis
- TUM School of Life Sciences, Technical University of Munich, Munich, Germany
| | - Manon Eckhardt
- Quantitative Biosciences Institute, University of California, San Francisco CA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco CA
- Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, CA
| | - Xin Chen
- Department of Bioengineering, University of California, San Francisco CA
| | - Kevan M Shokat
- Quantitative Biosciences Institute, University of California, San Francisco CA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco CA
- Howard Hughes Medical Institute, University of California, San Francisco CA
| | - Trey Ideker
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Nevan J Krogan
- Quantitative Biosciences Institute, University of California, San Francisco CA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco CA
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco
- Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, CA
| | - John D Gordan
- Division of Hematology/Oncology, University of California, San Francisco CA
- Quantitative Biosciences Institute, University of California, San Francisco CA
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2
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Sivasudhan E, Zhou J, Ma J, Wang Y, Liu S, Khan FI, Lu Z, Meng J, Blake N, Rong R. Hepatitis B Virus X Protein Contributes to Hepatocellular Carcinoma via Upregulation of KIAA1429 Methyltransferase and mRNA m6A Hypermethylation of HSPG2/Perlecan. Mol Carcinog 2025; 64:108-125. [PMID: 39412412 DOI: 10.1002/mc.23830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Revised: 09/12/2024] [Accepted: 09/27/2024] [Indexed: 12/13/2024]
Abstract
Chronic hepatitis B virus (HBV) remains to be the most common risk factor of hepatocellular carcinoma (HCC). While previous work has primarily focussed on understanding the direct and indirect mechanisms of Hepatitis B virus X protein (HBx)-mediated hepatocarcinogenesis, from genetic and epigenetic perspectives, its influence on RNA modification mediated onset of liver malignancies is less well understood. This study explored the role of HBV-encoded HBx in altering the m6A methylome profile and its implications on the pathogenesis of HCC. We established HBx-expressing stable HCC cell lines, Huh7-HBx and HepG2-HBx, and explored the transcriptomic and epitranscriptomic profiles by RNA-seq and MeRIP-seq, respectively. Preliminary results suggest that HBx promotes liver cell proliferation, migration, survival and overall m6A methylation in HCC cells and is involved in modulating the extracellular matrix. We show that HBx mediates liver cell transformation by upregulating KIAA1429 methyltransferase. HBx also drives the expression and hypermethylation of the extracellular matrix protein HSPG2/Perlecan and promotes tumourigenesis. Furthermore, we observed a potential interaction between KIAA1429 and HSPG2 in HCC liver cancer cells and demands further investigation.
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MESH Headings
- Humans
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/virology
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Viral Regulatory and Accessory Proteins
- Liver Neoplasms/genetics
- Liver Neoplasms/virology
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Gene Expression Regulation, Neoplastic
- Heparan Sulfate Proteoglycans/metabolism
- Heparan Sulfate Proteoglycans/genetics
- Hepatitis B virus/genetics
- Cell Proliferation
- Up-Regulation
- DNA Methylation
- RNA, Messenger/genetics
- Animals
- Cell Line, Tumor
- Mice
- Methyltransferases/metabolism
- Methyltransferases/genetics
- Hep G2 Cells
- Hepatitis B, Chronic/genetics
- Hepatitis B, Chronic/metabolism
- Hepatitis B, Chronic/virology
- Hepatitis B, Chronic/pathology
- Hepatitis B, Chronic/complications
- Cell Movement/genetics
- RNA-Binding Proteins
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Affiliation(s)
- Enakshi Sivasudhan
- Department of Biological Sciences, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Suzhou Municipal Key Lab of Cancer Biology and Chronic Disease, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Jingxian Zhou
- Suzhou Municipal Key Lab of Cancer Biology and Chronic Disease, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- School of AI and Advanced Computing, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Department of Computer Science, University of Liverpool, Liverpool, UK
| | - Jiongming Ma
- Department of Biological Sciences, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Suzhou Municipal Key Lab of Cancer Biology and Chronic Disease, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Yuanyuan Wang
- Department of Biological Sciences, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Suzhou Municipal Key Lab of Cancer Biology and Chronic Disease, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
| | - Siying Liu
- Department of Biological Sciences, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Suzhou Municipal Key Lab of Cancer Biology and Chronic Disease, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China
| | - Faez Iqbal Khan
- Department of Biological Sciences, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Suzhou Municipal Key Lab of Cancer Biology and Chronic Disease, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
| | - Zhiliang Lu
- Department of Biological Sciences, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Suzhou Municipal Key Lab of Cancer Biology and Chronic Disease, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Jia Meng
- Department of Biological Sciences, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Suzhou Municipal Key Lab of Cancer Biology and Chronic Disease, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Neil Blake
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Rong Rong
- Department of Biological Sciences, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Suzhou Municipal Key Lab of Cancer Biology and Chronic Disease, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, China
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
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3
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Shi F, Jiang J, Wang B, Hong L, Zhang Y, Meng Y, Zhang X, Gong L, Lin J, Diao H. Hepatitis B virus X protein promotes tumor glycolysis by downregulating lncRNA OIP5-AS1/HKDC1 in HCC. Cell Signal 2024; 119:111183. [PMID: 38636768 DOI: 10.1016/j.cellsig.2024.111183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 03/31/2024] [Accepted: 04/16/2024] [Indexed: 04/20/2024]
Abstract
Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality worldwide, with Hepatitis B virus (HBV) infection being the leading cause. This study aims to investigate the role of HBV in HCC pathogenesis involving glucose metabolism. Long non-coding RNA (lncRNA) OIP5-AS1 was significantly downregulated in HBV-positive HCC patients, and its low expression indicated a poor prognosis. This lncRNA was primarily localized in the cytoplasm, acting as a tumor suppressor. HBV protein X (HBx) repressed OIP5-AS1 expression by inhibiting a ligand-activated transcriptional factor peroxisome proliferator-activated receptor α (PPARα). Furthermore, mechanistic studies revealed that OIP5-AS1 inhibited tumor growth by suppressing Hexokinase domain component 1 (HKDC1)-mediated glycolysis. The expression of HKDC1 could be enhanced by transcriptional factor sterol regulatory element-binding protein 1 (SREBP1). OIP5-AS1 facilitated the ubiquitination and degradation of SREBP1 to suppress HKDC1 transcription, which inhibited glycolysis. The results suggest that lncRNA OIP5-AS1 plays an anti-oncogenic role in HBV-positive HCC via the HBx/OIP5-AS1/HKDC1 axis, providing a promising diagnostic marker and therapeutic target for HBV-positive HCC patients.
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MESH Headings
- RNA, Long Noncoding/genetics
- RNA, Long Noncoding/metabolism
- Humans
- Carcinoma, Hepatocellular/virology
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Liver Neoplasms/genetics
- Liver Neoplasms/virology
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Glycolysis/genetics
- Viral Regulatory and Accessory Proteins
- Trans-Activators/metabolism
- Trans-Activators/genetics
- Hexokinase/metabolism
- Hexokinase/genetics
- Gene Expression Regulation, Neoplastic
- Animals
- Hepatitis B virus
- Male
- Cell Line, Tumor
- Down-Regulation
- Mice
- Mice, Nude
- Female
- Sterol Regulatory Element Binding Protein 1/metabolism
- Sterol Regulatory Element Binding Protein 1/genetics
- Mice, Inbred BALB C
- PPAR alpha/metabolism
- PPAR alpha/genetics
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Affiliation(s)
- Fan Shi
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310000, PR China
| | - Jingjing Jiang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310000, PR China
| | - Baohua Wang
- Department of Ultrasound, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310000, PR China
| | - Liang Hong
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310000, PR China
| | - Yongting Zhang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310000, PR China
| | - Yuting Meng
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310000, PR China
| | - Xujun Zhang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310000, PR China
| | - Lan Gong
- Microbiome Research Centre, St George and Sutherland Clinical School, University of New South Wales, Sydney, NSW 2052, Australia
| | - Jianjun Lin
- Clinical Laboratory Department, The Affiliated Xiangshan Hospital of Wenzhou Medical University, Ningbo, Zhejiang 315700, PR China.
| | - Hongyan Diao
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310000, PR China.
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4
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Gordan JD, Keenan BP, Lim HC, Yarchoan M, Kelley RK. New Opportunities to Individualize Frontline Therapy in Advanced Stages of Hepatocellular Carcinoma. Drugs 2023; 83:1091-1109. [PMID: 37402062 DOI: 10.1007/s40265-023-01907-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2023] [Indexed: 07/05/2023]
Abstract
Hepatocellular carcinoma (HCC) is a leading cause of cancer death globally and is rising in incidence. Until recently, treatment options for patients with advanced stages of HCC have been limited to antiangiogenic therapies with modest improvements in overall survival. The emerging role of immunotherapy with immune checkpoint inhibitors (ICI) in oncology has led to a rapid expansion in treatment options and improvements in outcomes for patients with advanced stages of HCC. Recent clinical trials have shown meaningful survival improvement in patients treated with the combination of bevacizumab and atezolizumab, as well as with the combination of tremelimumab with durvalumab, resulting in regulatory approvals of these regimens as frontline therapy. Beyond improvements in overall survival, ICI-based combination regimens achieve higher rates of durable treatment response than multikinase inhibitors and have favorable side effect profiles. With the emergence of doublet anti-angiogenic and immune checkpoint inhibitor (ICI) and dual ICI combinations, individualized therapy is now possible for patients based on co-morbidity profiles and other factors. These more potent systemic therapies are also being tested in earlier stages of disease and in combination with loco-regional therapies such as trans-arterial chemoembolization and stereotactic body radiotherapy. We summarize these advances and emerging therapeutic combinations currently in clinical trials.
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Affiliation(s)
- John D Gordan
- Division of Hematology/Oncology, Helen Diller Family Comprehensive Cancer Center, UC San Francisco, San Francisco, CA, USA.
- Quantitative Biosciences Institute, UC San Francisco, San Francisco, CA, USA.
| | - Bridget P Keenan
- Division of Hematology/Oncology, Helen Diller Family Comprehensive Cancer Center, UC San Francisco, San Francisco, CA, USA
- Cancer Immunotherapy Program, Helen Diller Family Comprehensive Cancer Center, UC San Francisco, San Francisco, CA, USA
| | - Huat Chye Lim
- Division of Hematology/Oncology, Helen Diller Family Comprehensive Cancer Center, UC San Francisco, San Francisco, CA, USA
- Quantitative Biosciences Institute, UC San Francisco, San Francisco, CA, USA
| | - Mark Yarchoan
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - R Katie Kelley
- Division of Hematology/Oncology, Helen Diller Family Comprehensive Cancer Center, UC San Francisco, San Francisco, CA, USA
- Cancer Immunotherapy Program, Helen Diller Family Comprehensive Cancer Center, UC San Francisco, San Francisco, CA, USA
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5
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Testa U, Pelosi E, Castelli G. Clinical value of identifying genes that inhibit hepatocellular carcinomas. Expert Rev Mol Diagn 2022; 22:1009-1035. [PMID: 36459631 DOI: 10.1080/14737159.2022.2154658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
INTRODUCTION Primary liver cancer is a major health problem being the sixth most frequent cancer in the world and the fourth most frequent cause of cancer-related death in the world. The most common histological type of liver cancer is hepatocellular carcinoma (HCC, 75-80%). AREAS COVERED Based on primary literature, this review provides an updated analysis of studies of genetic characterization of HCC at the level of gene mutation profiling, copy number alterations and gene expression, with definition of molecular subgroups and identification of some molecular biomarkers and therapeutic targets. EXPERT OPINION A detailed and comprehensive study of the genetic abnormalities characterizing different HCC subsets represents a fundamental tool for a better understanding of the disease heterogeneity and for the identification of subgroups of patients responding or resistant to targeted treatments and for the discovery of new therapeutic targets. It is expected that a comprehensive characterization of these tumors may provide a fundamental contribution to improve the survival of a subset of HCC patients. Immunotherapy represents a new fundamental strategy for the treatment of HCC.
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Affiliation(s)
- Ugo Testa
- Department of Oncology, Istituto Superiore Di Sanità, ROME, ITALY
| | - Elvira Pelosi
- Department of Oncology, Istituto Superiore Di Sanità, ROME, ITALY
| | - Germana Castelli
- Department of Oncology, Istituto Superiore Di Sanità, ROME, ITALY
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6
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Funato K, Otsuka M, Sekiba K, Miyakawa Y, Seimiya T, Shibata C, Kishikawa T, Fujishiro M. Hepatitis B virus-associated hepatocellular carcinoma with Smc5/6 complex deficiency is susceptible to PARP inhibitors. Biochem Biophys Res Commun 2022; 607:89-95. [PMID: 35367833 DOI: 10.1016/j.bbrc.2022.03.137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 03/25/2022] [Indexed: 12/11/2022]
Abstract
DNA repair processes represent attractive synthetic lethal targets because many cancers exhibit impaired DNA repair pathways, which leads to dependence on specific repair proteins. The finding that poly (ADP-ribose) polymerase (PARP)-1 inhibitors are highly effective against cancers with deficient homologous recombination highlights the potential of this approach. In hepatitis B viral (HBV) infection, degradation of the structural maintenance of the chromosome 5/6 (Smc5/6) complex, which plays a key role in repairing double-stranded DNA breaks by homologous recombination, is induced by HBV regulatory protein X (HBx). Here, we hypothesized that a deficiency in the Smc5/6 complex in HBV-associated hepatocellular carcinoma (HCC) increases susceptibility to PARP inhibitors via a deficiency in homologous recombination. We confirmed impaired double-stranded DNA break repair in HBx-expressing HCC cells using a sensitive reporter to monitor homologous recombination. Treatment with a PARP inhibitor was significantly more effective against HBx-expressing HCC cells, and overexpression of Smc5/6 prevented these effects. Overall, our results suggest that homologous recombination deficiency in HBV-associated HCC leads to increased susceptibility to PARP inhibitors.
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Affiliation(s)
- Kazuyoshi Funato
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan
| | - Motoyuki Otsuka
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan.
| | - Kazuma Sekiba
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan
| | - Yu Miyakawa
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan
| | - Takahiro Seimiya
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan; Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Chikako Shibata
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan; Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Takahiro Kishikawa
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan
| | - Mitsuhiro Fujishiro
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan
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