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Bębnowska D, Hrynkiewicz R, Rzeszotek S, Freus M, Poniewierska-Baran A, Niedźwiedzka-Rystwej P. Apoptotic Cell Death in an Animal Model of Virus-Induced Acute Liver Failure-Observations during Lagovirus europaeus/GI.2 Infection. Int J Mol Sci 2024; 25:798. [PMID: 38255873 PMCID: PMC10815770 DOI: 10.3390/ijms25020798] [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: 12/05/2023] [Revised: 12/28/2023] [Accepted: 12/31/2023] [Indexed: 01/24/2024] Open
Abstract
Lagovirus europaeus/GI.2 causes severe and highly fatal Rabbit Hemorrhagic Disease (RHD). Because of its characteristics, this infection is used as an animal model for acute liver failure (ALF). Apoptosis is one of the key processes underlying ALF and has been described as one of the mechanisms of RHD pathogenesis. Apoptotic cell death has been quite well characterized in infection with different variants of GI.1 strains, but so far, the GI.2 genotype has not been widely studied. In this study, we performed an evaluation of apoptotic cell death in hepatocytes of rabbits infected with Lagovirus europaeus/GI.2. We analyzed the expression of genes involved in apoptotic cell death by real-time PCR and performed immunohistochemical (IHC) assays. We showed a significant increase in the expression of caspase-3 and the proapoptotic Bax and anti-apoptotic Bcl-2 in infected animals. In addition, we recorded increased Bax/Bcl-2 ratios. IHC analyses showed the presence of morphological signs of apoptosis in the hepatocytes of infected rabbits. Our results indicate that caspase-3 and proteins from the Bcl-2 families play a key role in apoptosis induced by Lagovirus europaeus/GI.2 infection.
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Affiliation(s)
- Dominika Bębnowska
- Institute of Biology, University of Szczecin, Felczaka 3c, 71-412 Szczecin, Poland; (R.H.); (A.P.-B.)
| | - Rafał Hrynkiewicz
- Institute of Biology, University of Szczecin, Felczaka 3c, 71-412 Szczecin, Poland; (R.H.); (A.P.-B.)
| | - Sylwia Rzeszotek
- Department of Histology and Embryology, Faculty of Medicine and Dentistry, Pomeranian Medical University in Szczecin, Powstańców Wlkp. 72, 70-111 Szczecin, Poland; (S.R.); (M.F.)
| | - Marika Freus
- Department of Histology and Embryology, Faculty of Medicine and Dentistry, Pomeranian Medical University in Szczecin, Powstańców Wlkp. 72, 70-111 Szczecin, Poland; (S.R.); (M.F.)
| | - Agata Poniewierska-Baran
- Institute of Biology, University of Szczecin, Felczaka 3c, 71-412 Szczecin, Poland; (R.H.); (A.P.-B.)
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2
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Skelin J, Tomaić V. Comparative Analysis of Alpha and Beta HPV E6 Oncoproteins: Insights into Functional Distinctions and Divergent Mechanisms of Pathogenesis. Viruses 2023; 15:2253. [PMID: 38005929 PMCID: PMC10674601 DOI: 10.3390/v15112253] [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: 10/27/2023] [Revised: 11/09/2023] [Accepted: 11/10/2023] [Indexed: 11/26/2023] Open
Abstract
Human papillomaviruses (HPVs) represent a diverse group of DNA viruses that infect epithelial cells of mucosal and cutaneous tissues, leading to a wide spectrum of clinical outcomes. Among various HPVs, alpha (α) and beta (β) types have garnered significant attention due to their associations with human health. α-HPVs are primarily linked to infections of the mucosa, with high-risk subtypes, such as HPV16 and HPV18, being the major etiological agents of cervical and oropharyngeal cancers. In contrast, β-HPVs are predominantly associated with cutaneous infections and are commonly found on healthy skin. However, certain β-types, notably HPV5 and HPV8, have been implicated in the development of non-melanoma skin cancers in immunocompromised individuals, highlighting their potential role in pathogenicity. In this review, we comprehensively analyze the similarities and differences between α- and β-HPV E6 oncoproteins, one of the major drivers of viral replication and cellular transformation, and how these impact viral fitness and the capacity to induce malignancy. In particular, we compare the mechanisms these oncoproteins use to modulate common cellular processes-apoptosis, DNA damage repair, cell differentiation, and the immune response-further shedding light on their shared and distinct features, which enable them to replicate at divergent locations of the human body and cause different types of cancer.
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Affiliation(s)
| | - Vjekoslav Tomaić
- Division of Molecular Medicine, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia;
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3
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Baj J, Forma A, Dudek I, Chilimoniuk Z, Dobosz M, Dobrzyński M, Teresiński G, Buszewicz G, Flieger J, Portincasa P. The Involvement of Human Papilloma Virus in Gastrointestinal Cancers. Cancers (Basel) 2022; 14:cancers14112607. [PMID: 35681587 PMCID: PMC9179480 DOI: 10.3390/cancers14112607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/21/2022] [Accepted: 05/22/2022] [Indexed: 01/27/2023] Open
Abstract
Human Papilloma Virus (HPV) is one of the most common sexually transmitted infections worldwide. HPV infection has a strong relationship with the onset of cervix uteri, vagina, penis, anus, and oropharynx, but also tonsils and tongue cancers. Some epidemiological data indicate that except for gynecologic cancers, HPV infection can be one of the risk factors associated with a greater risk of induction and progression of gastrointestinal cancers. Data, however, remain contradictory and definite conclusions cannot be drawn, so far. The following review aims to organize recent evidence and summarize the current state of knowledge regarding the association between HPV infection and gastrointestinal tumors primarily focusing on esophageal, liver, gastric, colorectal, and anal cancers.
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Affiliation(s)
- Jacek Baj
- Department of Anatomy, Medical University of Lublin, Jaczewskiego 4, 20-090 Lublin, Poland
- Correspondence: (J.B.); (A.F.)
| | - Alicja Forma
- Department of Forensic Medicine, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland; (I.D.); (Z.C.); (M.D.); (M.D.); (G.T.); (G.B.)
- Correspondence: (J.B.); (A.F.)
| | - Iga Dudek
- Department of Forensic Medicine, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland; (I.D.); (Z.C.); (M.D.); (M.D.); (G.T.); (G.B.)
| | - Zuzanna Chilimoniuk
- Department of Forensic Medicine, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland; (I.D.); (Z.C.); (M.D.); (M.D.); (G.T.); (G.B.)
| | - Maciej Dobosz
- Department of Forensic Medicine, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland; (I.D.); (Z.C.); (M.D.); (M.D.); (G.T.); (G.B.)
| | - Michał Dobrzyński
- Department of Forensic Medicine, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland; (I.D.); (Z.C.); (M.D.); (M.D.); (G.T.); (G.B.)
| | - Grzegorz Teresiński
- Department of Forensic Medicine, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland; (I.D.); (Z.C.); (M.D.); (M.D.); (G.T.); (G.B.)
| | - Grzegorz Buszewicz
- Department of Forensic Medicine, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland; (I.D.); (Z.C.); (M.D.); (M.D.); (G.T.); (G.B.)
| | - Jolanta Flieger
- Department of Analytical Chemistry, Medical University of Lublin, Chodźki 4A, 20-093 Lublin, Poland;
| | - Piero Portincasa
- Clinica Medica “A. Murri”, Department of Biomedical Sciences & Human Oncology, University of Bari Medical School, 70124 Bari, Italy;
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Lee J, Lee D, Kim Y. Mathematical model of STAT signalling pathways in cancer development and optimal control approaches. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210594. [PMID: 34631119 PMCID: PMC8479343 DOI: 10.1098/rsos.210594] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 09/03/2021] [Indexed: 06/10/2023]
Abstract
In various diseases, the STAT family display various cellular controls over various challenges faced by the immune system and cell death programs. In this study, we investigate how an intracellular signalling network (STAT1, STAT3, Bcl-2 and BAX) regulates important cellular states, either anti-apoptosis or apoptosis of cancer cells. We adapt a mathematical framework to illustrate how the signalling network can generate a bi-stability condition so that it will induce either apoptosis or anti-apoptosis status of tumour cells. Then, we use this model to develop several anti-tumour strategies including IFN-β infusion. The roles of JAK-STATs signalling in regulation of the cell death program in cancer cells and tumour growth are poorly understood. The mathematical model unveils the structure and functions of the intracellular signalling and cellular outcomes of the anti-tumour drugs in the presence of IFN-β and JAK stimuli. We identify the best injection order of IFN-β and DDP among many possible combinations, which may suggest better infusion strategies of multiple anti-cancer agents at clinics. We finally use an optimal control theory in order to maximize anti-tumour efficacy and minimize administrative costs. In particular, we minimize tumour volume and maximize the apoptotic potential by minimizing the Bcl-2 concentration and maximizing the BAX level while minimizing total injection amount of both IFN-β and JAK2 inhibitors (DDP).
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Affiliation(s)
- Jonggul Lee
- Pierre Louis Institute of Epidemiology and Public Health, Paris 75012, France
| | - Donggu Lee
- Department of Mathematics, Konkuk University, Seoul 05029, Republic of Korea
| | - Yangjin Kim
- Department of Mathematics, Konkuk University, Seoul 05029, Republic of Korea
- Mathematical Biosciences Institute, Columbus, OH 43210, USA
- Department of Neurosurgery, Harvard Medical School & Brigham and Women’s Hospital, Boston MA 02115, USA
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5
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Vats A, Trejo-Cerro O, Thomas M, Banks L. Human papillomavirus E6 and E7: What remains? Tumour Virus Res 2021; 11:200213. [PMID: 33716206 PMCID: PMC7972986 DOI: 10.1016/j.tvr.2021.200213] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/12/2022] Open
Abstract
Decades of research on the human papillomavirus oncogenes, E6 and E7, have given us huge amounts of data on their expression, functions and structures. We know much about the very many cellular proteins and pathways that they influence in one way or another. However, much of this information is quite discrete, referring to one activity examined under one condition. It is now time to join the dots to try to understand a larger picture: how, where and when do all these interactions occur... and why? Examining these questions will also show how many of the yet obscure cellular processes work together for cellular and tissue homeostasis in health and disease.
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Affiliation(s)
- Arushi Vats
- Tumour Virology Group, ICGEB, AREA Science Park, Trieste, 34149, Italy
| | - Oscar Trejo-Cerro
- Tumour Virology Group, ICGEB, AREA Science Park, Trieste, 34149, Italy
| | - Miranda Thomas
- Tumour Virology Group, ICGEB, AREA Science Park, Trieste, 34149, Italy.
| | - Lawrence Banks
- Tumour Virology Group, ICGEB, AREA Science Park, Trieste, 34149, Italy
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Sen P, Ghosal S, Hazra R, Mohanty R, Arega S, Sahu B, Ganguly N. CRISPR-mediated knockdown of miR-214 modulates cell fate in response to anti-cancer drugs in HPV-negative and HPV-positive cervical cancer cells. J Biosci 2020. [DOI: 10.1007/s12038-020-00054-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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7
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Cyprian FS, Al-Farsi HF, Vranic S, Akhtar S, Al Moustafa AE. Epstein-Barr Virus and Human Papillomaviruses Interactions and Their Roles in the Initiation of Epithelial-Mesenchymal Transition and Cancer Progression. Front Oncol 2018; 8:111. [PMID: 29765906 PMCID: PMC5938391 DOI: 10.3389/fonc.2018.00111] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 03/29/2018] [Indexed: 12/27/2022] Open
Abstract
Oncoviruses are implicated in around 20% of all human cancers including both solid and non-solid malignancies. Epstein–Barr virus (EBV) and human papillomaviruses (HPVs) are the most common oncoviruses worldwide. Currently, it is well established that onco-proteins of EBV (LMP1, LMP2A, and EBNA1) and high-risk HPVs (E5 and E6/E7) play an important role in the initiation and/or progression of several human carcinomas, including cervical, oral, and breast. More significantly, it has been recently pointed out that viral onco-proteins of EBV and high-risk HPVs can be co-present and consequently cooperate to initiate and/or amplify epithelial–mesenchymal transition (EMT), which is the hallmark of cancer progression and metastasis. This could occur by β-catenin, JAK/STAT/SRC, PI3k/Akt/mTOR, and/or RAS/MEK/ERK signaling pathways, which onco-proteins of EBV and HPVs share. This review presents the most recent advances related to EBV and high-risk HPVs onco-proteins interactions and their roles in the progression of human carcinomas especially oral and breast via the initiation of EMT.
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Affiliation(s)
| | | | - Semir Vranic
- College of Medicine, Qatar University, Doha, Qatar
| | | | - Ala-Eddin Al Moustafa
- College of Medicine, Qatar University, Doha, Qatar.,Biomedical Research Centre, Qatar University, Doha, Qatar.,Oncology Department, McGill University, Montreal, Quebec, Canada
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8
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Cruz-Gregorio A, Manzo-Merino J, Lizano M. Cellular redox, cancer and human papillomavirus. Virus Res 2018; 246:35-45. [DOI: 10.1016/j.virusres.2018.01.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 01/10/2018] [Accepted: 01/10/2018] [Indexed: 12/28/2022]
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9
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Pan-Cancer Analysis Links PARK2 to BCL-XL-Dependent Control of Apoptosis. Neoplasia 2016; 19:75-83. [PMID: 28038320 PMCID: PMC5198112 DOI: 10.1016/j.neo.2016.12.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 12/04/2016] [Accepted: 12/06/2016] [Indexed: 11/23/2022] Open
Abstract
Mutation of the PARK2 gene can promote both Parkinson's Disease and cancer, yet the underlying mechanisms of how PARK2 controls cellular physiology is incompletely understood. Here, we show that the PARK2 tumor suppressor controls the apoptotic regulator BCL-XL and modulates programmed cell death. Analysis of approximately 10,000 tumor genomes uncovers a striking pattern of mutual exclusivity between PARK2 genetic loss and amplification of BCL2L1, implicating these genes in a common pathway. PARK2 directly binds to and ubiquitinates BCL-XL. Inactivation of PARK2 leads to aberrant accumulation of BCL-XL both in vitro and in vivo, and cancer-specific mutations in PARK2 abrogate the ability of the ubiquitin E3 ligase to target BCL-XL for degradation. Furthermore, PARK2 modulates mitochondrial depolarization and apoptosis in a BCL-XL-dependent manner. Thus, like genes at the nodal points of growth arrest pathways such as p53, the PARK2 tumor suppressor is able to exert its antiproliferative effects by regulating both cell cycle progression and programmed cell death.
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10
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Altamura G, Corteggio A, Pacini L, Conte A, Pierantoni GM, Tommasino M, Accardi R, Borzacchiello G. Transforming properties of Felis catus papillomavirus type 2 E6 and E7 putative oncogenes in vitro and their transcriptional activity in feline squamous cell carcinoma in vivo. Virology 2016; 496:1-8. [PMID: 27236740 DOI: 10.1016/j.virol.2016.05.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 04/12/2016] [Accepted: 05/20/2016] [Indexed: 01/18/2023]
Abstract
Felis catus papillomavirus type 2 (FcaPV2) DNA is found in feline cutaneous squamous cell carcinomas (SCCs); however, its biological properties are still uncharacterized. In this study, we successfully expressed FcaPV2 E6 and E7 putative oncogenes in feline epithelial cells and demonstrated that FcaPV2 E6 binds to p53, impairing its protein level. In addition, E6 and E7 inhibited ultraviolet B (UVB)-triggered accumulation of p53, p21 and pro-apoptotic markers such as Cleaved Caspase3, Bax and Bak, suggesting a synergistic action of the virus with UV exposure in tumour pathogenesis. Furthermore, FcaPV2 E7 bound to feline pRb and impaired pRb levels, resulting in upregulation of the downstream pro-proliferative genes Cyclin A and Cdc2. Importantly, we demonstrated mRNA expression of FcaPV2 E2, E6 and E7 in feline SCC samples, strengthening the hypothesis of a causative role in the development of feline SCC.
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Affiliation(s)
- Gennaro Altamura
- Department of Veterinary Medicine and Animal Productions, General Pathology and Pathological Anatomy Unit, University of Naples Federico II, Via Delpino 1, 80137 Naples, Italy.
| | - Annunziata Corteggio
- Department of Veterinary Medicine and Animal Productions, General Pathology and Pathological Anatomy Unit, University of Naples Federico II, Via Delpino 1, 80137 Naples, Italy.
| | - Laura Pacini
- Infections and Cancer Biology Group, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon, France.
| | - Andrea Conte
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Via Pansini 5, 80131 Naples, Italy.
| | - Giovanna Maria Pierantoni
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Via Pansini 5, 80131 Naples, Italy.
| | - Massimo Tommasino
- Infections and Cancer Biology Group, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon, France.
| | - Rosita Accardi
- Infections and Cancer Biology Group, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon, France.
| | - Giuseppe Borzacchiello
- Department of Veterinary Medicine and Animal Productions, General Pathology and Pathological Anatomy Unit, University of Naples Federico II, Via Delpino 1, 80137 Naples, Italy.
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11
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Al Moustafa AE, Al-Awadhi R, Missaoui N, Adam I, Durusoy R, Ghabreau L, Akil N, Ahmed HG, Yasmeen A, Alsbeih G. Human papillomaviruses-related cancers. Presence and prevention strategies in the Middle east and north African regions. Hum Vaccin Immunother 2015; 10:1812-21. [PMID: 25424787 DOI: 10.4161/hv.28742] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Human papillomavirus (HPV) infections are estimated to be the most common sexually transmitted infections worldwide. Meanwhile, it is well established that infection by high-risk HPVs is considered the major cause of cervical cancer since more than 96% of these cancers are positive for high-risk HPVs, especially types 16 and 18. Moreover, during the last 2 decades, numerous studies pointed-out the possible involvement of high-risk HPV in several human carcinomas including head and neck, colorectal and breast cancers. The association between high-risk HPVs and cervical cancer and potentially other human malignancies would necessitate the introduction of vaccines which were generated against the 2 most frequent high-risk HPVs (types 16 and 18) worldwide, including the Middle East (ME) as well as North African countries. The presence of high-risk HPVs in the pathogenesis of human cancers in the ME, which is essential in order to evaluate the importance of vaccination against HPVs, has not been fully investigated yet. In this review, we present an overview of the existing epidemiological evidence regarding the presence of HPV in human cancers in the ME and the potential impact of vaccination against HPV infections and its outcome on human health in this region.
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12
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Holloway A, Simmonds M, Azad A, Fox JL, Storey A. Resistance to UV-induced apoptosis by β-HPV5 E6 involves targeting of activated BAK for proteolysis by recruitment of the HERC1 ubiquitin ligase. Int J Cancer 2014; 136:2831-43. [PMID: 25408501 DOI: 10.1002/ijc.29350] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 11/04/2014] [Indexed: 11/11/2022]
Abstract
UV exposure is the main etiological agent in the development of non-melanoma skin cancer (NMSC), but mounting evidence suggests a co-factorial role for β-genus HPV types early in tumor initiation or progression. UV damage initiates an apoptotic response, driven at the mitochondrial level by BCL-2 family proteins, that eliminates damaged cells that may accumulate deleterious mutations and acquire tumorigenic properties. BAK is a pro-apoptotic BCL-2 protein that functions ultimately to form pores that permeabilize the mitochondrial outer membrane, thereby committing a cell to death, a process involving changes in BAK phosphorylation and conformation. The E6 protein of β-type HPV5 signals BAK for proteasomal degradation, a function that confers protection from UV-induced apoptosis. We find that HPV5 E6 does not constitutively target BAK for proteolysis, but targets the latter stages of BAK activation, following changes in phosphorylation and conformation. A mutational analysis identified the lysine residue on BAK required for proteolysis, and a functional siRNA screen identified the HECT domain E3 ubiquitin ligase HERC1 as being required for E6-mediated BAK degradation. We show that HERC1 interacts with BAK in E6-expressing cells that have been damaged by UV, and provide evidence that the interaction of HERC1 with BAK requires access to a hydrophobic surface on BAK that binds BH3 domains of BCL-2 proteins. We also show that HERC1 contains a putative BH3 domain that can bind to BAK. These findings reveal a specific and unique mechanism used by the HPV5 E6 protein to target BAK.
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Affiliation(s)
- Amy Holloway
- Department of Oncology, Weatherall Institute of Molecular Medicine,University of Oxford, OX3 9DS, United Kingdom
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13
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Sominsky S, Kuslansky Y, Shapiro B, Jackman A, Haupt Y, Rosin-Arbesfeld R, Sherman L. HPV16 E6 and E6AP differentially cooperate to stimulate or augment Wnt signaling. Virology 2014; 468-470:510-523. [PMID: 25262469 DOI: 10.1016/j.virol.2014.09.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 08/05/2014] [Accepted: 09/08/2014] [Indexed: 01/24/2023]
Abstract
The present study investigated the roles of E6 and E6AP in the Wnt pathway. We showed that E6 levels are markedly reduced in cells in which Wnt signaling is activated. Coexpression of wild-type or mutant E6AP (C820A) in Wnt-activated cells stabilized E6 and enhanced Wnt/β-catenin/TCF transcription. Expression of E6AP alone in nonstimulated cells elevated β-catenin level, promoted its nuclear accumulation, and activated β-catenin/TCF transcription. A knockdown of E6AP lowered β-catenin levels. Coexpression with E6 intensified the activities of E6AP. Further experiments proved that E6AP/E6 stabilize β-catenin by protecting it from proteasomal degradation. This function was dependent on the catalytic activity of E6AP, the kinase activity of GSK3β and the susceptibility of β-catenin to GSK3β phosphorylation. Thus, this study identified E6AP as a novel regulator of the Wnt signaling pathway, capable of cooperating with E6 in stimulating or augmenting Wnt/β-catenin signaling, thereby possibly contributing to HPV carcinogenesis.
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Affiliation(s)
- Sophia Sominsky
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Yael Kuslansky
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Beny Shapiro
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Anna Jackman
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Ygal Haupt
- Research Division, The Peter MacCallum Cancer Centre, East Melbourne, Australia.
| | - Rina Rosin-Arbesfeld
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Levana Sherman
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
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14
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Pan-cancer genetic analysis identifies PARK2 as a master regulator of G1/S cyclins. Nat Genet 2014; 46:588-94. [PMID: 24793136 DOI: 10.1038/ng.2981] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 04/11/2014] [Indexed: 12/15/2022]
Abstract
Coordinate control of different classes of cyclins is fundamentally important for cell cycle regulation and tumor suppression, yet the underlying mechanisms are incompletely understood. Here we show that the PARK2 tumor suppressor mediates this coordination. The PARK2 E3 ubiquitin ligase coordinately controls the stability of both cyclin D and cyclin E. Analysis of approximately 5,000 tumor genomes shows that PARK2 is a very frequently deleted gene in human cancer and uncovers a striking pattern of mutual exclusivity between PARK2 deletion and amplification of CCND1, CCNE1 or CDK4-implicating these genes in a common pathway. Inactivation of PARK2 results in the accumulation of cyclin D and acceleration of cell cycle progression. Furthermore, PARK2 is a component of a new class of cullin-RING-containing ubiquitin ligases targeting both cyclin D and cyclin E for degradation. Thus, PARK2 regulates cyclin-CDK complexes, as does the CDK inhibitor p16, but acts as a master regulator of the stability of G1/S cyclins.
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15
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Gabriel JE, de Figueiredo DDLG, de Farias RP. Revealing highly conserved regions in the E6 protein among distinct human papillomavirus types using comparative analysis of multiple sequence alignments. BRAZ J BIOL 2013; 73:449-50. [DOI: 10.1590/s1519-69842013000200030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 05/11/2012] [Indexed: 11/21/2022] Open
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16
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RXRα deletion and E6E7 oncogene expression are sufficient to induce cervical malignant lesions in vivo. Cancer Lett 2012; 317:226-36. [DOI: 10.1016/j.canlet.2011.11.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 11/23/2011] [Accepted: 11/23/2011] [Indexed: 01/01/2023]
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17
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Nunes CT, Miners KL, Dolton G, Pepper C, Fegan C, Mason MD, Man S. A novel tumor antigen derived from enhanced degradation of bax protein in human cancers. Cancer Res 2011; 71:5435-44. [PMID: 21697278 DOI: 10.1158/0008-5472.can-11-0393] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cancer cells frequently exhibit defects in apoptosis, which contribute to increased survival and chemotherapeutic resistance. For example, genetic mutations or abnormal proteasomal degradation can reduce expression of Bax which limits apoptosis. In cancers where abnormal proteasomal degradation of Bax occurs, we hypothesized that Bax peptides that bind to human leukocyte antigen (HLA) class I molecules would be generated for presentation to CD8(+) T cells. To test this hypothesis, we generated T cells against pooled Bax peptides, using the blood of healthy human donors. Although T-cell responses were of low frequency (0.15%), a CD8(+) T-cell clone (KSIVB17) was isolated that optimally recognized Bax(136-144) peptide (IMGWTLDFL) presented by HLA-A*0201. KSIVB17 was able to recognize and kill a variety of HLA-matched cancer cells including primary tumor cells from chronic lymphocytic leukemia (CLL). No reactivity was seen against HLA-matched, nontransformed cells such as PHA blasts and skin fibroblasts. Furthermore, KSIVB17 reactivity corresponded with the proteasomal degradation patterns of Bax protein observed in cancer cells. Taken together, our findings suggest a new concept for tumor antigens based on regulatory proteins that are ubiquitously expressed in normal cells, but that have abnormally enhanced degradation in cancer cells. Bax degradation products offer candidate immune antigens in cancers such as CLL in which increased Bax degradation correlates with poor clinical prognosis.
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Affiliation(s)
- Cláudia Trindade Nunes
- Departments of Infection, Immunity and Biochemistry, School of Medicine, Cardiff University, Cardiff, Wales, United Kingdom
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18
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Heaton PR, Deyrieux AF, Bian XL, Wilson VG. HPV E6 proteins target Ubc9, the SUMO conjugating enzyme. Virus Res 2011; 158:199-208. [PMID: 21510985 DOI: 10.1016/j.virusres.2011.04.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2011] [Revised: 04/03/2011] [Accepted: 04/04/2011] [Indexed: 12/31/2022]
Abstract
The human papillomavirus oncogenic protein, E6, interacts with a number of cellular proteins, and for some targets, E6 directs their degradation through the ubiquitin-proteasome pathway. Post-translational modification with ubiquitin-like modifiers, such as SUMO, also influences protein activities, protein-protein interactions, and protein stability. We report that the high risk HPVE6 proteins reduce the intracellular quantity of the sole SUMO conjugation enzyme, Ubc9, concomitant with decreased host sumoylation. E6 did not significantly influence transcription of Ubc9, indicating that the effects were likely at the protein level. Consistent with typical E6-mediated proteasomal degradation, E6 bound to Ubc9 in vitro, and required E6AP for reduction of Ubc9 levels. Under stable E6 expression conditions in differentiating keratinocytes there was a decrease in Ubc9 and a loss of numerous sumoylated targets indicating a significant perturbation of the normal sumoylation profile. While E6 is known to inhibit PIASy, a SUMO ligase, our results suggest that HPV E6 also targets the Ubc9 protein to modulate host cell sumoylation, suggesting that the sumoylation system may be an important target during viral reproduction and possibly the subsequent development of cervical cancer.
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Affiliation(s)
- Phillip R Heaton
- Department of Microbial and Molecular Pathogenesis, College of Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, USA
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19
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Interaction between ultraviolet radiation and human papillomavirus. Cancer Treat Res 2009. [PMID: 19415201 DOI: 10.1007/978-0-387-78574-5_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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20
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21
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Struijk L, van der Meijden E, Kazem S, Ter Schegget J, de Gruijl FR, Steenbergen RDM, Feltkamp MCW. Specific betapapillomaviruses associated with squamous cell carcinoma of the skin inhibit UVB-induced apoptosis of primary human keratinocytes. J Gen Virol 2008; 89:2303-2314. [PMID: 18753241 DOI: 10.1099/vir.0.83317-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Epidemiological studies have shown an association between infections by specific betapapillomaviruses, such as human papillomavirus (HPV) types 5 and 8, and cutaneous squamous cell carcinoma (SCC). The role of betapapillomaviruses in the development of cutaneous SCC is, however, still enigmatic. The ability to inhibit UVB-induced apoptosis, as demonstrated for HPV5 in vitro, may be important in this respect, as survival of DNA-damaged and mutated cells increases the risk of transformation. The aim of this study was to assess whether inhibition of UVB-induced apoptosis is a general property of betapapillomaviruses and to identify apoptotic factors that are potentially involved in this process. Primary human keratinocytes transduced with E6 and E7 of selected betapapillomaviruses (HPV5, HPV8, HPV15, HPV20, HPV24 and HPV38) were characterized and subjected to UVB irradiation. HPV8- and HPV20-expressing keratinocytes in particular showed fewer signs of apoptosis, as demonstrated by lower levels of active caspase 3, less enzymic caspase activity and less DNA fragmentation. The observed inhibition of UVB-induced apoptosis was mediated by E6 and coincided with reduced steady-state expression of the pro-apoptotic protein Bax. In conclusion, E6 of HPV8 and HPV20 reduces the apoptotic responses upon UVB irradiation when expressed in primary human keratinocytes. Infections with HPV8 and HPV20 may therefore augment the carcinogenic effect of UV radiation and potentially contribute to oncogenic transformation of the skin.
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Affiliation(s)
- Linda Struijk
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Els van der Meijden
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Siamaque Kazem
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jan Ter Schegget
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Frank R de Gruijl
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Mariet C W Feltkamp
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
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22
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The interaction between human papillomavirus type 16 and FADD is mediated by a novel E6 binding domain. J Virol 2008; 82:9600-14. [PMID: 18632871 DOI: 10.1128/jvi.00538-08] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
High-risk strains of human papillomavirus, such as types 16 and 18, have been etiologically linked to cervical cancer. Most cervical cancer tissues are positive for both the E6 and E7 oncoproteins, since it is their cooperation that results in successful transformation and immortalization of infected cells. We have reported that E6 binds to tumor necrosis factor receptor 1 and to Fas-associated death domain (FADD) and, in doing so, prevents E6-expressing cells from responding to apoptotic stimuli. The binding site of E6 to FADD localizes to the first 23 amino acids of FADD and has now been further characterized by the use of deletion and site-directed mutants of FADD in pull-down and functional assays. The results from these experiments revealed that mutations of serine 16, serine 18, and leucine 20 obstruct FADD binding to E6, suggesting that these residues are part of the E6 binding domain on FADD. Because FADD does not contain the two previously identified E6 binding motifs, the LxxphiLsh motif, and the PDZ motif, a novel binding domain for E6 has been identified on FADD. Furthermore, peptides that correspond to this region can block E6/FADD binding in vitro and can resensitize E6-expressing cells to apoptotic stimuli in vivo. These results demonstrate the existence of a novel E6 binding domain.
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23
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Liu HC, Chen GG, Vlantis AC, Tse GM, Chan ATC, van Hasselt CA. Inhibition of apoptosis in human laryngeal cancer cells by E6 and E7 oncoproteins of human papillomavirus 16. J Cell Biochem 2008; 103:1125-43. [PMID: 17668439 DOI: 10.1002/jcb.21490] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The carcinogenesis of human papillomaviruses type 16 (HPV-16) is mainly due to its two oncoproteins, E6 and E7. Their carcinogenic features in term of their relationship with Bcl-2 family are still unclear. We thus aimed to analyze the expression of Bcl-2 family members, Bcl-2, Bax, and Bak in laryngeal cancer cells transfected with the E6 or E7 and to determine the sensitivity of these cells to apoptotic stimuli. We employed two human laryngeal cancer cell lines, UMSCC12 and UMSCC11A in this study. These two cell lines were stably transfected with HPV16 E6, E7 or empty vector, pcDNA3.1. We found that E6 and E7 inhibited apoptosis induced by TNF-alpha/CHX in both UMSCC11A and UMSCC12 cells, enhanced the stability of Bcl-2 protein and increased the degradation of Bak protein. Furthermore, it was found that HPV-16 E7 statistically enhanced the expression of Bcl-2 in laryngeal cancer. The alteration of Bak by E6 and E7 was not through the influence on the Bak promoter, as the luciferase assay showed that neither E6 nor E7 changed the Bak promoter activity. We conclude that the evasion of apoptosis mediated by HPV-16 E6 and E7 is associated with increased Bcl-2 and decreased Bak in laryngeal carcinogenesis and that the decreased level of Bak by E6 and E7 is not caused by the regulation of the Bak promoter but by reducing its protein stability.
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Affiliation(s)
- Han Ching Liu
- Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
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24
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Rieck GC, Fiander AN. Human papillomavirus, cervical carcinogenesis and chemoprevention with Indole derivates - a review of pathomechanisms. Mol Nutr Food Res 2007; 52:105-13. [DOI: 10.1002/mnfr.200700138] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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25
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Wang J, An H, Mayo MW, Baldwin AS, Yarbrough WG. LZAP, a putative tumor suppressor, selectively inhibits NF-kappaB. Cancer Cell 2007; 12:239-51. [PMID: 17785205 DOI: 10.1016/j.ccr.2007.07.002] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Revised: 04/26/2007] [Accepted: 07/06/2007] [Indexed: 12/16/2022]
Abstract
LZAP has been reported to inhibit cellular proliferation and clonogenic growth. Here, we report that decreased LZAP expression promoted cellular transformation, xenograft tumor growth, and xenograft tumor vascularity. Loss of LZAP also increased cellular invasion, and MMP-9 expression dependent on NF-kappaB. LZAP directly bound to RelA, impaired serine 536 phosphorylation of RelA, increased HDAC association with RelA, inhibited basal and stimulated NF-kappaB transcriptional activity, and was found at the promoter of selective NF-kappaB-responsive genes. LZAP protein levels were markedly decreased in 32% of primary HNSCCs (n = 28) and decreased LZAP levels in primary HNSCC correlated with increased expression of the NF-kappaB-regulated genes IL-8 and IkappaBalpha. In aggregate, these data support a role of LZAP in NF-kappaB regulation and tumor suppression.
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Affiliation(s)
- Jialiang Wang
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232, USA
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26
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Filippova M, Johnson MM, Bautista M, Filippov V, Fodor N, Tungteakkhun SS, Williams K, Duerksen-Hughes PJ. The large and small isoforms of human papillomavirus type 16 E6 bind to and differentially affect procaspase 8 stability and activity. J Virol 2007; 81:4116-29. [PMID: 17267478 PMCID: PMC1866154 DOI: 10.1128/jvi.01924-06] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Accepted: 01/23/2007] [Indexed: 11/20/2022] Open
Abstract
Human papillomavirus type 16 (HPV-16) has developed numerous ways to modulate host-initiated immune mechanisms. The HPV-16 E6 oncoprotein, for example, can modulate the cellular level, and consequently the activity, of procaspase 8, thus modifying the cellular response to cytokines of the tumor necrosis factor family. E6 from HPV-16, but not E6 from the low-risk types 6b and 11, alters the cellular level of procaspase 8 in a dose-dependent manner. Both the large and small (E6*) isoforms of E6, which originate by way of alternate splicing, can modulate procaspase 8 stability. Intriguingly, although both isoforms bind to procaspase 8, the large isoform accelerates the degradation of procaspase 8 while the small isoform stabilizes it. Binding leads to a change in the ability of procaspase 8 to bind either to itself or to FADD (Fas-associated death domain), with the large version of E6 able to inhibit this binding while the small isoform does not. Consistent with this model, knockdown of the large version of E6 by small interfering RNA leads to increases in the levels of procaspase 8 and its binding to both itself and FADD. Thus, these alternatively spliced isoforms can modulate both the level and the activity of procaspase 8 in opposite directions.
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Affiliation(s)
- Maria Filippova
- Department of Biochemistry and Microbiology, 11085 Campus Street, 121 Mortensen Hall, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
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27
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Asadurian Y, Kurilin H, Lichtig H, Jackman A, Gonen P, Tommasino M, Zehbe I, Sherman L. Activities of human papillomavirus 16 E6 natural variants in human keratinocytes. J Med Virol 2007; 79:1751-60. [PMID: 17854024 DOI: 10.1002/jmv.20978] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Genetic variations in the E6 oncogene have been associated with different risk for cancer progression. In the present study, the functional significance of human papillomavirus (HPV) polymorphism in the E6 oncogene was investigated. Ten HPV16 E6 variants containing amino acid substitutions in the N-terminal region of E6 were evaluated for different biological and biochemical activities in human keratinocytes, the target cells for HPV infection. Western blot analyses of primary foreskin human keratinocytes or immortalized human keratinocytes, stably transduced with the E6 variants, revealed reduced p53 and Bax levels in all E6 expressing cultures. The reduction induced by most E6 proteins was at similar levels and comparable to the reduction induced by the E6 prototype. The ability of the proteins to induce serum/calcium-differentiation resistant colonies in primary keratinocytes was more variable. Overall activities of the variants ranged between 0.24- and 2.18-fold of the E6 prototype activity. The I27R/L83V variant showed the lowest activity whereas the R8Q variant showed the highest activity. The L83V polymorphism previously associated with risk for cancer progression in some populations, showed significant activity, comparable to that of the E6 prototype, in reducing p53 and Bax levels. Furthermore, this variant showed enhancement in the ability to induce colonies resistant to serum/calcium-triggered differentiation, however, the difference from the prototype was not statistically significant. This, and augmentation of other described functions might result in differences in L83V pathogenicity.
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Affiliation(s)
- Yulia Asadurian
- Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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28
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Lichtig H, Algrisi M, Botzer LE, Abadi T, Verbitzky Y, Jackman A, Tommasino M, Zehbe I, Sherman L. HPV16 E6 natural variants exhibit different activities in functional assays relevant to the carcinogenic potential of E6. Virology 2006; 350:216-27. [PMID: 16519914 DOI: 10.1016/j.virol.2006.01.038] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 01/09/2006] [Accepted: 01/26/2006] [Indexed: 01/16/2023]
Abstract
Genetic studies have revealed natural amino acid variations within the human papillomavirus (HPV) type 16 E6 oncoprotein. To address the functional significance of E6 polymorphisms, 10 HPV16 E6 variants isolated from cervical lesions of Swedish women were evaluated for their activities in different in vitro and in vivo assays relevant to the carcinogenic potential of E6. Small differences between E6 prototype and variants, and among variants, were observed in transient expression assays that assessed p53 degradation, Bax degradation, and inhibition of p53 transactivation. More variable levels of activities were exhibited by the E6 proteins in assays that evaluated binding to the E6-binding protein (E6BP) or the human discs large protein (hDlg). The E6 prototype expressed moderate to high activity in the above assays. The L83V polymorphism, previously associated with risk for cancer progression in some populations, expressed similar levels of activity as that of the E6 prototype in most functional assays. On the other hand, L83V displayed more efficient degradation of Bax and binding to E6BP, but lower binding to hDlg. Results of this study indicate that naturally occurring amino acid variations in HPV16 E6 can alter activities of the protein important for its carcinogenic potential.
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Affiliation(s)
- Hava Lichtig
- Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel, and Thunder Bay Regional Health Sciences Centre, Regional Cancer Care Program, Ontario, Canada
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29
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Vogt M, Butz K, Dymalla S, Semzow J, Hoppe-Seyler F. Inhibition of Bax activity is crucial for the antiapoptotic function of the human papillomavirus E6 oncoprotein. Oncogene 2006; 25:4009-15. [PMID: 16462759 DOI: 10.1038/sj.onc.1209429] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Oncogenic types of human papillomaviruses (HPVs) cause cervical cancer in humans. The antiapoptotic viral E6 gene has been identified as a key factor for maintaining the viability of HPV-positive cancer cells. Although E6 has the potential to modulate many apoptosis regulators, the crucial apoptotic pathway blocked by endogenous E6 in cervical cancer cells remained unknown. Using RNA interference (RNAi), here, we show that targeted inhibition of E6 expression in cervical cancer cells leads to the transcriptional stimulation of the PUMA promoter, in a p53-dependent manner. This is linked to the activation and translocation of Bax to the mitochondrial membrane, cytochrome c release into the cytosol, and activation of caspase-3, in a PUMA-dependent manner. Moreover, inhibition of Bax expression by RNAi efficiently reverts the apoptotic phenotype, which results from inhibition of E6 expression. Thus, interference with the p53/PUMA/Bax cascade is crucial for the antiapoptotic function of the viral E6 oncogene in HPV-positive cancer cells.
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Affiliation(s)
- M Vogt
- Deutsches Krebsforschungszentrum, Arbeitsgruppe Molekulare Therapie Virus-assoziierter Tumore (F065), Im Neuenheimer Feld 242, Heidelberg, Germany
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