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Scarsella L, Ehrke-Schulz E, Paulussen M, Thal SC, Ehrhardt A, Aydin M. Advances of Recombinant Adenoviral Vectors in Preclinical and Clinical Applications. Viruses 2024; 16:377. [PMID: 38543743 PMCID: PMC10974029 DOI: 10.3390/v16030377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 02/14/2024] [Accepted: 02/19/2024] [Indexed: 05/23/2024] Open
Abstract
Adenoviruses (Ad) have the potential to induce severe infections in vulnerable patient groups. Therefore, understanding Ad biology and antiviral processes is important to comprehend the signaling cascades during an infection and to initiate appropriate diagnostic and therapeutic interventions. In addition, Ad vector-based vaccines have revealed significant potential in generating robust immune protection and recombinant Ad vectors facilitate efficient gene transfer to treat genetic diseases and are used as oncolytic viruses to treat cancer. Continuous improvements in gene delivery capacity, coupled with advancements in production methods, have enabled widespread application in cancer therapy, vaccine development, and gene therapy on a large scale. This review provides a comprehensive overview of the virus biology, and several aspects of recombinant Ad vectors, as well as the development of Ad vector, are discussed. Moreover, we focus on those Ads that were used in preclinical and clinical applications including regenerative medicine, vaccine development, genome engineering, treatment of genetic diseases, and virotherapy in tumor treatment.
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Affiliation(s)
- Luca Scarsella
- Department of Anesthesiology, Center for Clinical and Translational Research, Helios University Hospital Wuppertal, Witten/Herdecke University, 42283 Wuppertal, Germany;
- Virology and Microbiology, Center for Biomedical Education and Research (ZBAF), Department Human Medicine, Faculty of Health, Witten/Herdecke University, 58453 Witten, Germany; (E.E.-S.); (A.E.)
- Laboratory of Experimental Pediatric Pneumology and Allergology, Center for Biomedical Education and Science (ZBAF), Department of Human Medicine, Faculty of Medicine, Witten/Herdecke University, 58453 Witten, Germany
| | - Eric Ehrke-Schulz
- Virology and Microbiology, Center for Biomedical Education and Research (ZBAF), Department Human Medicine, Faculty of Health, Witten/Herdecke University, 58453 Witten, Germany; (E.E.-S.); (A.E.)
| | - Michael Paulussen
- Chair of Pediatrics, University Children’s Hospital, Vestische Kinder- und Jugendklinik Datteln, Witten/Herdecke University, 45711 Datteln, Germany;
| | - Serge C. Thal
- Department of Anesthesiology, Center for Clinical and Translational Research, Helios University Hospital Wuppertal, Witten/Herdecke University, 42283 Wuppertal, Germany;
| | - Anja Ehrhardt
- Virology and Microbiology, Center for Biomedical Education and Research (ZBAF), Department Human Medicine, Faculty of Health, Witten/Herdecke University, 58453 Witten, Germany; (E.E.-S.); (A.E.)
| | - Malik Aydin
- Virology and Microbiology, Center for Biomedical Education and Research (ZBAF), Department Human Medicine, Faculty of Health, Witten/Herdecke University, 58453 Witten, Germany; (E.E.-S.); (A.E.)
- Laboratory of Experimental Pediatric Pneumology and Allergology, Center for Biomedical Education and Science (ZBAF), Department of Human Medicine, Faculty of Medicine, Witten/Herdecke University, 58453 Witten, Germany
- Chair of Pediatrics, University Children’s Hospital, Vestische Kinder- und Jugendklinik Datteln, Witten/Herdecke University, 45711 Datteln, Germany;
- Institute for Medical Laboratory Diagnostics, Center for Clinical and Translational Research, Helios University Hospital Wuppertal, Witten/Herdecke University, 42283 Wuppertal, Germany
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Prusinkiewicz MA, Mymryk JS. Metabolic Control by DNA Tumor Virus-Encoded Proteins. Pathogens 2021; 10:560. [PMID: 34066504 PMCID: PMC8148605 DOI: 10.3390/pathogens10050560] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/01/2021] [Accepted: 05/04/2021] [Indexed: 12/15/2022] Open
Abstract
Viruses co-opt a multitude of host cell metabolic processes in order to meet the energy and substrate requirements for successful viral replication. However, due to their limited coding capacity, viruses must enact most, if not all, of these metabolic changes by influencing the function of available host cell regulatory proteins. Typically, certain viral proteins, some of which can function as viral oncoproteins, interact with these cellular regulatory proteins directly in order to effect changes in downstream metabolic pathways. This review highlights recent research into how four different DNA tumor viruses, namely human adenovirus, human papillomavirus, Epstein-Barr virus and Kaposi's associated-sarcoma herpesvirus, can influence host cell metabolism through their interactions with either MYC, p53 or the pRb/E2F complex. Interestingly, some of these host cell regulators can be activated or inhibited by the same virus, depending on which viral oncoprotein is interacting with the regulatory protein. This review highlights how MYC, p53 and pRb/E2F regulate host cell metabolism, followed by an outline of how each of these DNA tumor viruses control their activities. Understanding how DNA tumor viruses regulate metabolism through viral oncoproteins could assist in the discovery or repurposing of metabolic inhibitors for antiviral therapy or treatment of virus-dependent cancers.
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Affiliation(s)
| | - Joe S. Mymryk
- Department of Microbiology and Immunology, Western University, London, ON N6A 3K7, Canada;
- Department of Otolaryngology, Head & Neck Surgery, Western University, London, ON N6A 3K7, Canada
- Department of Oncology, Western University, London, ON N6A 3K7, Canada
- London Regional Cancer Program, Lawson Health Research Institute, London, ON N6C 2R5, Canada
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Songock WK, Kim SM, Bodily JM. The human papillomavirus E7 oncoprotein as a regulator of transcription. Virus Res 2016; 231:56-75. [PMID: 27818212 DOI: 10.1016/j.virusres.2016.10.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 10/27/2016] [Indexed: 12/12/2022]
Abstract
High-risk human papillomaviruses (HPVs) encode oncoproteins which manipulate gene expression patterns in the host keratinocytes to facilitate viral replication, regulate viral transcription, and promote immune evasion and persistence. In some cases, oncoprotein-induced changes in host cell behavior can cause progression to cancer, but a complete picture of the functions of the viral oncoproteins in the productive HPV life cycle remains elusive. E7 is the HPV-encoded factor most responsible for maintaining cell cycle competence in differentiating keratinocytes. Through interactions with dozens of host factors, E7 has an enormous impact on host gene expression patterns. In this review, we will examine the role of E7 specifically as a regulator of transcription. We will discuss mechanisms of regulation of cell cycle-related genes by E7 as well as genes involved in immune regulation, growth factor signaling, DNA damage responses, microRNAs, and others pathways. We will also discuss some unanswered questions about how transcriptional regulation by E7 impacts the biology of HPV in both benign and malignant conditions.
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Affiliation(s)
- William K Songock
- Department of Microbiology and Immunology and Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Seong-Man Kim
- Department of Microbiology and Immunology and Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Jason M Bodily
- Department of Microbiology and Immunology and Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
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Kelishadi M, Kelishadi M, Moradi A, Javid N, Bazouri M, Tabarraei A. human adenoviruses role in ophthalmic pterygium formation. Jundishapur J Microbiol 2015; 8:e16871. [PMID: 26034543 PMCID: PMC4449841 DOI: 10.5812/jjm.16871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Revised: 05/31/2014] [Accepted: 06/08/2014] [Indexed: 02/05/2023] Open
Abstract
Background: Ophthalmic pterygium is a common benign lesion of unknown origin and the pathogenesis might be vision-threatening. This problem is often associated with exposure to solar light. Recent evidence suggests that potentially oncogenic viruses such as human papillomavirus and Epstein-Barr virus may be involved in the pathogenesis of pterygia. Expression of specific adenovirus genes such as E1A and E1B, which potentially have many functions, may contribute to their oncogenic activity as well as relevance to cellular immortalization. Objectives: For the first time, we aimed to investigate involvement of adenoviruses in pterygium formation. Patients and Methods: Fifty tissue specimens of pterygium from patients undergoing pterygium surgery (as cases), 50 conjunctival swab samples from the same patients and 10 conjunctival biopsy specimens from individuals without pterygium such as patients undergoing cataract surgery (as controls) were analyzed for evidence of adenovirus infection with polymerase chain reaction using specific primers chosen from the moderately conserved region of the hexon gene. Furthermore, β-globin primers were used to access the quality of extracted DNA. Data was analyzed using SPSS (version 16) software. Results: Of 50 patients, 20 were men and 30 women with mean age of 61.1 ± 16.9 years ranged between 22 and 85 years. All samples of pterygia had positive results for adenoviruses DNA with polymerase chain reaction, but none of the negative control groups displayed adenoviruses. The pterygium group and the control groups were β-globin positive. Direct sequencing of PCR products confirmed Adenovirus infection. Conclusions: Adenoviruses might act as a possible cause of pterygium formation and other factors could play a synergistic role in the development. However, further larger studies are required to confirm this hypothesis.
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Affiliation(s)
- Mishar Kelishadi
- Infectious Diseases Research Center, Golestan University of Medical Sciences, Gorgan, IR Iran
| | | | - Abdolvahab Moradi
- Infectious Diseases Research Center, Golestan University of Medical Sciences, Gorgan, IR Iran
| | - Naeme Javid
- Infectious Diseases Research Center, Golestan University of Medical Sciences, Gorgan, IR Iran
| | - Masoud Bazouri
- Infectious Diseases Research Center, Golestan University of Medical Sciences, Gorgan, IR Iran
| | - Alijan Tabarraei
- Infectious Diseases Research Center, Golestan University of Medical Sciences, Gorgan, IR Iran
- Corresponding author: Alijan Tabarraei, Infectious Diseases Research Center, Golestan University of Medical Sciences, Gorgan, IR Iran. Tel: +98-1714422652, Fax: +98-1714440225, E-mail:
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Impact of the adenoviral E4 Orf3 protein on the activity and posttranslational modification of p53. J Virol 2015; 89:3209-20. [PMID: 25568206 DOI: 10.1128/jvi.03072-14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED Our previous studies have established that the p53 populations that accumulate in normal human cells exposed to etoposide or infected by an E1B 55-kDa protein-null mutant of human adenovirus type 5 carry a large number of posttranslational modifications at numerous residues (C. J. DeHart, J. S. Chahal, S. J. Flint, and D. H. Perlman, Mol Cell Proteomics 13:1-17, 2014, http://dx.doi.org/10.1074/mcp.M113.030254). In the absence of this E1B protein, the p53 transcriptional program is not induced, and it has been reported that the viral E4 Orf3 protein inactivates p53 (C. Soria, F. E. Estermann, K. C. Espantman, and C. C. O'Shea, Nature 466:1076-1081, 2010, http://dx.doi.org/10.1038/nature09307). As the latter protein disrupts nuclear Pml bodies, sites at which p53 is modified, we used mass spectrometry to catalogue the posttranscriptional modifications of the p53 population that accumulates when neither the E1B 55-kDa nor the E4 Orf3 protein is made in infected cells. Eighty-five residues carrying 163 modifications were identified. The overall patterns of posttranslational modification of this population and p53 present in cells infected by an E1B 55-kDa-null mutant were similar. The efficiencies with which the two forms of p53 bound to a consensus DNA recognition sequence could not be distinguished and were lower than that of transcriptionally active p53. The absence of the E4 Orf3 protein increased expression of several p53-responsive genes when the E1B protein was also absent from infected cells. However, expression of these genes did not attain the levels observed when p53 was activated in response to etoposide treatment and remained lower than those measured in mock-infected cells. IMPORTANCE The tumor suppressor p53, a master regulator of cellular responses to stress, is inactivated and destroyed in cells infected by species C human adenoviruses, such as type 5. It is targeted for proteasomal degradation by the action of a virus-specific E3 ubiquitin ligase that contains the viral E1B 55-kDa and E4 Orf6 proteins, while the E4 Orf3 protein has been reported to block its ability to stimulate expression of p53-dependent genes. The comparisons reported here of the posttranslational modifications and activities of p53 populations that accumulate in infected normal human cells in the absence of both mechanisms of inactivation or of only the E3 ligase revealed little impact of the E4 Orf3 protein. These observations indicate that E4 Orf3-dependent disruption of Pml bodies does not have a major effect on the pattern of p53 posttranslational modifications in adenovirus-infected cells. Furthermore, they suggest that one or more additional viral proteins contribute to blocking p53 activation and the consequences that are deleterious for viral reproduction, such as apoptosis or cell cycle arrest.
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p53 tumor suppressor protein stability and transcriptional activity are targeted by Kaposi's sarcoma-associated herpesvirus-encoded viral interferon regulatory factor 3. Mol Cell Biol 2013; 34:386-99. [PMID: 24248600 DOI: 10.1128/mcb.01011-13] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Viruses have developed numerous strategies to counteract the host cell defense. Kaposi's sarcoma-associated herpesvirus (KSHV) is a DNA tumor virus linked to the development of Kaposi's sarcoma, Castleman's disease, and primary effusion lymphoma (PEL). The virus-encoded viral interferon regulatory factor 3 (vIRF-3) gene is a latent gene which is involved in the regulation of apoptosis, cell cycle, antiviral immunity, and tumorigenesis. vIRF-3 was shown to interact with p53 and inhibit p53-mediated apoptosis. However, the molecular mechanism underlying this phenomenon has not been established. Here, we show that vIRF-3 associates with the DNA-binding domain of p53, inhibits p53 phosphorylation on serine residues S15 and S20, and antagonizes p53 oligomerization and the DNA-binding affinity. Furthermore, vIRF-3 destabilizes p53 protein by increasing the levels of p53 polyubiquitination and targeting p53 for proteasome-mediated degradation. Consequently, vIRF-3 attenuates p53-mediated transcription of the growth-regulatory p21 gene. These effects of vIRF-3 are of biological relevance since the knockdown of vIRF-3 expression in KSHV-positive BC-3 cells, derived from PEL, leads to an increase in p53 phosphorylation, enhancement of p53 stability, and activation of p21 gene transcription. Collectively, these data suggest that KSHV evolved an efficient mechanism to downregulate p53 function and thus facilitate uncontrolled cell proliferation and tumor growth.
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Wang F, Marshall CB, Ikura M. Transcriptional/epigenetic regulator CBP/p300 in tumorigenesis: structural and functional versatility in target recognition. Cell Mol Life Sci 2013; 70:3989-4008. [PMID: 23307074 PMCID: PMC11113169 DOI: 10.1007/s00018-012-1254-4] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 11/08/2012] [Accepted: 12/20/2012] [Indexed: 01/19/2023]
Abstract
In eukaryotic cells, gene transcription is regulated by sequence-specific DNA-binding transcription factors that recognize promoter and enhancer elements near the transcriptional start site. Some coactivators promote transcription by connecting transcription factors to the basal transcriptional machinery. The highly conserved coactivators CREB-binding protein (CBP) and its paralog, E1A-binding protein (p300), each have four separate transactivation domains (TADs) that interact with the TADs of a number of DNA-binding transcription activators as well as general transcription factors (GTFs), thus mediating recruitment of basal transcription machinery to the promoter. Most promoters comprise multiple activator-binding sites, and many activators contain tandem TADs, thus multivalent interactions may stabilize CBP/p300 at the promoter, and intrinsically disordered regions in CBP/p300 and many activators may confer adaptability to these multivalent complexes. CBP/p300 contains a catalytic histone acetyltransferase (HAT) domain, which remodels chromatin to 'relax' its superstructure and enables transcription of proximal genes. The HAT activity of CBP/p300 also acetylates some transcription factors (e.g., p53), hence modulating the function of key transcriptional regulators. Through these numerous interactions, CBP/p300 has been implicated in complex physiological and pathological processes, and, in response to different signals, can drive cells towards proliferation or apoptosis. Dysregulation of the transcriptional and epigenetic functions of CBP/p300 is associated with leukemia and other types of cancer, thus it has been recognized as a potential anti-cancer drug target. In this review, we focus on recent exciting findings in the structural mechanisms of CBP/p300 involving multivalent and dynamic interactions with binding partners, which may pave new avenues for anti-cancer drug development.
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Affiliation(s)
- Feng Wang
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 2M9 Canada
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 1L7 Canada
- Present Address: Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - Christopher B. Marshall
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 2M9 Canada
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 1L7 Canada
| | - Mitsuhiko Ikura
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 2M9 Canada
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 1L7 Canada
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Yano S, Tazawa H, Hashimoto Y, Shirakawa Y, Kuroda S, Nishizaki M, Kishimoto H, Uno F, Nagasaka T, Urata Y, Kagawa S, Hoffman RM, Fujiwara T. A genetically engineered oncolytic adenovirus decoys and lethally traps quiescent cancer stem-like cells in S/G2/M phases. Clin Cancer Res 2013; 19:6495-505. [PMID: 24081978 DOI: 10.1158/1078-0432.ccr-13-0742] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE Because chemoradiotherapy selectively targets proliferating cancer cells, quiescent cancer stem-like cells are resistant. Mobilization of the cell cycle in quiescent leukemia stem cells sensitizes them to cell death signals. However, it is unclear that mobilization of the cell cycle can eliminate quiescent cancer stem-like cells in solid cancers. Thus, we explored the use of a genetically-engineered telomerase-specific oncolytic adenovirus, OBP-301, to mobilize the cell cycle and kill quiescent cancer stem-like cells. EXPERIMENTAL DESIGN We established CD133(+) cancer stem-like cells from human gastric cancer MKN45 and MKN7 cells. We investigated the efficacy of OBP-301 against quiescent cancer stem-like cells. We visualized the treatment dynamics of OBP-301 killing of quiescent cancer stem-like cells in dormant tumor spheres and xenografts using a fluorescent ubiquitination cell-cycle indicator (FUCCI). RESULTS CD133(+) gastric cancer cells had stemness properties. OBP-301 efficiently killed CD133(+) cancer stem-like cells resistant to chemoradiotherapy. OBP-301 induced cell-cycle mobilization from G0-G1 to S/G2/M phases and subsequent cell death in quiescent CD133(+) cancer stem-like cells by mobilizing cell-cycle-related proteins. FUCCI enabled visualization of quiescent CD133(+) cancer stem-like cells and proliferating CD133(-) non-cancer stem-like cells. Three-dimensional visualization of the cell-cycle behavior in tumor spheres showed that CD133(+) cancer stem-like cells maintained stemness by remaining in G0-G1 phase. We showed that OBP-301 mobilized quiescent cancer stem-like cells in tumor spheres and xenografts into S/G2/M phases where they lost viability and cancer stem-like cell properties and became chemosensitive. CONCLUSION Oncolytic adenoviral infection is an effective mechanism of cancer cell killing in solid cancer and can be a new therapeutic paradigm to eliminate quiescent cancer stem-like cells.
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Affiliation(s)
- Shuya Yano
- Authors' Affiliations: Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences; Center for innovative clinical medicine, Okayama University Hospital, Okayama; Oncolys BioPharma, Inc., Tokyo, Japan; Department of Surgery, University of California San Diego; and AntiCancer, Inc., San Diego, California
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Svyatchenko VA, Tarasova MV, Netesov SV, Chumakov PM. Oncolytic adenoviruses in anticancer therapy: Current status and prospects. Mol Biol 2012. [DOI: 10.1134/s0026893312040103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Yamasaki Y, Tazawa H, Hashimoto Y, Kojima T, Kuroda S, Yano S, Yoshida R, Uno F, Mizuguchi H, Ohtsuru A, Urata Y, Kagawa S, Fujiwara T. A novel apoptotic mechanism of genetically engineered adenovirus-mediated tumour-specific p53 overexpression through E1A-dependent p21 and MDM2 suppression. Eur J Cancer 2012; 48:2282-91. [PMID: 22244827 DOI: 10.1016/j.ejca.2011.12.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Revised: 12/15/2011] [Accepted: 12/17/2011] [Indexed: 10/14/2022]
Abstract
Oncolytic viruses engineered to replicate in tumour cells but not in normal cells could be used as tumour-specific vectors carrying the therapeutic genes. We previously developed a telomerase-specific oncolytic adenovirus, OBP-301, that causes cell death in human cancer cells with telomerase activities. Here, we further modified OBP-301 to express the wild-type p53 tumour suppressor gene (OBP-702), and investigated whether OBP-702 induces stronger antitumour activity than OBP-301. The antitumour effect of OBP-702 was compared to that of OBP-301 on OBP-301-sensitive (H358 and H460) and OBP-301-resistant (T.Tn and HSC4) human cancer cells. OBP-702 suppressed the viability of both OBP-301-sensitive and OBP-301-resistant cancer cells more efficiently than OBP-301. OBP-702 caused increased apoptosis compared to OBP-301 or a replication-deficient adenovirus expressing the p53 gene (Ad-p53) in H358 and T.Tn cells. Adenovirus E1A-mediated p21 and MDM2 downregulation was involved in the apoptosis caused by OBP-702. Moreover, OBP-702 significantly suppressed tumour growth in subcutaneous tumour xenograft models compared to monotherapy with OBP-301 or Ad-p53. Our data demonstrated that OBP-702 infection expressed adenovirus E1A and then inhibited p21 and MDM2 expression, which in turn efficiently induced apoptotic cell death. This novel apoptotic mechanism suggests that the p53-expressing OBP-702 is a promising antitumour reagent for human cancer and could improve the clinical outcome.
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Affiliation(s)
- Yasumoto Yamasaki
- Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
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Lenos K, de Lange J, Teunisse AFAS, Lodder K, Verlaan-de Vries M, Wiercinska E, van der Burg MJM, Szuhai K, Jochemsen AG. Oncogenic functions of hMDMX in in vitro transformation of primary human fibroblasts and embryonic retinoblasts. Mol Cancer 2011; 10:111. [PMID: 21910853 PMCID: PMC3179748 DOI: 10.1186/1476-4598-10-111] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 09/12/2011] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND In around 50% of all human cancers the tumor suppressor p53 is mutated. It is generally assumed that in the remaining tumors the wild-type p53 protein is functionally impaired. The two main inhibitors of p53, hMDM2 (MDM2) and hMDMX (MDMX/MDM4) are frequently overexpressed in wild-type p53 tumors. Whereas the main activity of hMDM2 is to degrade p53 protein, its close homolog hMDMX does not degrade p53, but it represses its transcriptional activity. Here we study the role of hMDMX in the neoplastic transformation of human fibroblasts and embryonic retinoblasts, since a high number of retinoblastomas contain elevated hMDMX levels. METHODS We made use of an in vitro transformation model using a retroviral system of RNA interference and gene overexpression in primary human fibroblasts and embryonic retinoblasts. Consecutive knockdown of RB and p53, overexpression of SV40-small t, oncogenic HRasV12 and HA-hMDMX resulted in a number of stable cell lines representing different stages of the transformation process, enabling a comparison between loss of p53 and hMDMX overexpression. The cell lines were tested in various assays to assess their oncogenic potential. RESULTS Both p53-knockdown and hMDMX overexpression accelerated proliferation and prevented growth suppression induced by introduction of oncogenic Ras, which was required for anchorage-independent growth and the ability to form tumors in vivo. Furthermore, we found that hMDMX overexpression represses basal p53 activity to some extent. Transformed fibroblasts with very high levels of hMDMX became largely resistant to the p53 reactivating drug Nutlin-3. The Nutlin-3 response of hMDMX transformed retinoblasts was intact and resembled that of retinoblastoma cell lines. CONCLUSIONS Our studies show that hMDMX has the essential properties of an oncogene. Its constitutive expression contributes to the oncogenic phenotype of transformed human cells. Its main function appears to be p53 inactivation. Therefore, developing new drugs targeting hMDMX is a valid approach to obtain new treatments for a subset of human tumors expressing wild-type p53.
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Affiliation(s)
- Kristiaan Lenos
- Department of Molecular Cell Biology, Leiden University Medical Center, P,O, Box 9600, 2300 RC Leiden, The Netherlands
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Saha A, Kaul R, Murakami M, Robertson ES. Tumor viruses and cancer biology: Modulating signaling pathways for therapeutic intervention. Cancer Biol Ther 2010; 10:961-78. [PMID: 21084867 DOI: 10.4161/cbt.10.10.13923] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Tumor viruses have provided relatively simple genetic systems, which can be manipulated for understanding the molecular mechanisms of the cellular transformation process. A growing body of information in the tumor virology field provides several prospects for rationally targeted therapies. However, further research is needed to better understand the multiple mechanisms utilized by these viruses in cancer progression in order to develop therapeutic strategies. Initially viruses were believed to be associated with cancers as causative agents only in animals. It was almost half a century before the first human tumor virus, Epstein-Barr virus (EBV), was identified in 1964. Subsequently, several human tumor viruses have been identified including Kaposi sarcoma associated herpesvirus (KSHV), human Papillomaviruses (HPV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Human T lymphotropic virus (HTLV-1) and recently identified Merkel cell Polyomavirus (MCPyV). Tumor viruses are sub-categorized as either DNA viruses, which include EBV, KSHV, HPV, HBV, and MCPyV, or RNA viruses such as HCV and HTLV-1. Tumor-viruses induce oncogenesis through manipulating an array of different cellular pathways. These viruses initiate a series of cellular events, which lead to immortalization and proliferation of the infected cells by disrupting the mitotic checkpoint upon infection of the host cell. This is often accomplished by functional inhibition or proteasomal degradation of many tumor suppressor proteins by virally encoded gene products. The virally infected cells can either be eliminated via cell-mediated apoptosis or persist in a state of chronic infection. Importantly, the chronic persistence of infection by tumor viruses can lead to oncogenesis. This review discusses the major human tumor associated viruses and their ability to modulate numerous cell signaling pathways, which can be targeted for potential therapeutic approaches.
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Affiliation(s)
- Abhik Saha
- Department of Microbiology and Tumor Virology, University of Pennsylvania School of Medicine, Philadelphia, USA
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Infection with E1B-mutant adenovirus stabilizes p53 but blocks p53 acetylation and activity through E1A. Oncogene 2010; 30:865-75. [PMID: 20935676 DOI: 10.1038/onc.2010.461] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Wild-type adenovirus type 5 eliminates p53 through the E1B-55kDa and E4-34kDa gene products. Deletion or mutation of E1B-55kDa has long been thought to confer p53-selective replication of oncolytic viruses. We show here that infection with E1B-defective adenovirus mutants induces massive accumulation of p53, without obvious defects in p53 localization, phosphorylation, conformation and oligomerization. Nonetheless, p53 completely failed to induce its target genes in this scenario, for example, p21/CDKN1A, Mdm2 and PUMA. Two regions of the E1A gene products independently contributed to the suppression of p21 transcription. Depending on the E1A conserved region 3, E1B-defective adenovirus impaired the ability of the transcription factor Sp1 to bind the p21 promoter. Moreover, the amino terminal region of E1A, binding the acetyl transferases p300 and CREB-binding protein, blocked p53 K382 acetylation in infected cells. Mutating either of these E1A regions, in addition to E1B, partially restored p21 mRNA levels. Our findings argue that adenovirus attenuates p53-mediated p21 induction, through at least two E1B-independent mechanisms. Other virus species and cancer cells may employ analogous strategies to impair p53 activity.
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Lou JJW, Chua YL, Chew EH, Gao J, Bushell M, Hagen T. Inhibition of hypoxia-inducible factor-1alpha (HIF-1alpha) protein synthesis by DNA damage inducing agents. PLoS One 2010; 5:e10522. [PMID: 20479887 PMCID: PMC2866540 DOI: 10.1371/journal.pone.0010522] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 04/12/2010] [Indexed: 12/22/2022] Open
Abstract
Hypoxia-inducible factor (HIF) is a heterodimeric transcription factor that is composed of a hypoxia-inducible α subunit (HIF-1α and HIF-2α) and a constitutively expressed β subunit (HIF-1β). HIF mediates the adaptation of cells and tissues to low oxygen concentrations. It also plays an important role in tumorigenesis and constitutes an important therapeutic target in anti-tumor therapy. We have screened a number of reported HIF inhibitors for their effects on HIF-transcriptional activity and found that the DNA damage inducing agents camptothecin and mitomycin C produced the most robust effects. Camptothecin is a reported inhibitor of HIF-1α translation, while mitomycin C has been reported to induce p53-dependent HIF-1α degradation. In this study we demonstrate that the inhibitory effect of mitomycin C on HIF-1α protein expression is not dependent on p53 and protein degradation, but also involves HIF-1α translational regulation. Initiation of a DNA damage response with the small molecule p53 activator NSC-652287 (RITA) has been reported to inhibit HIF-1α protein synthesis by increasing the phosphorylation of eIF2α. However, we show here that even when eIF2α phosphorylation is prevented, the DNA damage inducing drugs mitomycin C, camptothecin and NSC-652287 still inhibit HIF-1α protein synthesis to the same extent. The inhibitory effects of camptothecin on HIF-1α expression but not that of mitomycin C and NSC-652287 were dependent on cyclin-dependent kinase activity. In conclusion, specific types of DNA damage can bring about selective inhibition of HIF-1α protein synthesis. Further characterization of the involved mechanisms may reveal important novel therapeutic targets.
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Affiliation(s)
- Jessica Jie Wei Lou
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Yee Liu Chua
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Eng Hui Chew
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jie Gao
- School of Pharmacy, University of Nottingham, University Park, Nottingham, United Kingdom
| | - Martin Bushell
- School of Pharmacy, University of Nottingham, University Park, Nottingham, United Kingdom
| | - Thilo Hagen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- * E-mail:
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Structural basis for subversion of cellular control mechanisms by the adenoviral E1A oncoprotein. Proc Natl Acad Sci U S A 2009; 106:13260-5. [PMID: 19651603 DOI: 10.1073/pnas.0906770106] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The adenovirus early region 1A (E1A) oncoprotein mediates cell transformation by deregulating host cellular processes and activating viral gene expression by recruitment of cellular proteins that include cyclic-AMP response element binding (CREB) binding protein (CBP)/p300 and the retinoblastoma protein (pRb). While E1A is capable of independent interaction with CBP/p300 or pRb, simultaneous binding of both proteins is required for maximal biological activity. To obtain insights into the mechanism by which E1A hijacks the cellular transcription machinery by competing with essential transcription factors for binding to CBP/p300, we have determined the structure of the complex between the transcriptional adaptor zinc finger-2 (TAZ2) domain of CBP and the conserved region-1 (CR1) domain of E1A. The E1A CR1 domain is unstructured in the free state and upon binding folds into a local helical structure mediated by an extensive network of intermolecular hydrophobic contacts. By NMR titrations, we show that E1A efficiently competes with the N-terminal transactivation domain of p53 for binding to TAZ2 and that pRb interacts with E1A at 2 independent sites located in CR1 and CR2. We show that pRb and the CBP TAZ2 domain can bind simultaneously to the CR1 site of E1A to form a ternary complex and propose a structural model for the pRb:E1A:CBP complex on the basis of published x-ray data for homologous binary complexes. These observations reveal the molecular basis by which E1A inhibits p53-mediated transcriptional activation and provide a rationale for the efficiency of cellular transformation by the adenoviral E1A oncoprotein.
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Yi F, Saha A, Murakami M, Kumar P, Knight JS, Cai Q, Choudhuri T, Robertson ES. Epstein-Barr virus nuclear antigen 3C targets p53 and modulates its transcriptional and apoptotic activities. Virology 2009; 388:236-47. [PMID: 19394062 DOI: 10.1016/j.virol.2009.03.027] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 03/09/2009] [Accepted: 03/21/2009] [Indexed: 01/17/2023]
Abstract
The p53 tumor suppressor gene is one of the most commonly mutated genes in human cancers and the corresponding encoded protein induces apoptosis or cell-cycle arrest at the G1/S checkpoint in response to DNA damage. To date, previous studies have shown that antigens encoded by human tumor viruses such as SV40 large T antigen, adenovirus E1A and HPV E6 interact with p53 and disrupt its functional activity. In a similar fashion, we now show that EBNA3C, one of the EBV latent antigens essential for the B-cell immortalization in vitro, interacts directly with p53. Additionally, we mapped the interaction of EBNA3C with p53 to the C-terminal DNA-binding and the tetramerization domain of p53, and the region of EBNA3C responsible for binding to p53 was mapped to the N-terminal domain of EBNA3C (residues 130-190), previously shown to interact with a number of important cell-cycle components, specifically SCF(Skp2), cyclin A, and cMyc. Furthermore, we demonstrate that EBNA3C substantially represses the transcriptional activity of p53 in luciferase based reporter assays, and rescues apoptosis induced by ectopic p53 expression in SAOS-2 (p53(-/-)) cells. Interestingly, we also show that the DNA-binding ability of p53 is diminished in the presence of EBNA3C. Thus, the interaction between the p53 and EBNA3C provides new insights into the mechanism(s) by which the EBNA3C oncoprotein can alter cellular gene expression in EBV associated human cancers.
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Affiliation(s)
- Fuming Yi
- Department of Microbiology and Tumor Virology Program, Abramson Comprehensive Cancer Center, University of Pennsylvania Medical School, 201E Johnson Pavilion, 3610 Hamilton Walk, PA 19104, USA
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17
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Cha EJ, Oh BC, Wee HJ, Chi XZ, Goh YM, Lee KS, Ito Y, Bae SC. E1A physically interacts with RUNX3 and inhibits its transactivation activity. J Cell Biochem 2008; 105:236-44. [PMID: 18570183 DOI: 10.1002/jcb.21818] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The adenoviral gene, termed early region 1A (E1A), is crucial for transformation and has been used very effectively as a tool to determine the molecular mechanisms that underlie the basis of cellular transformation. pRb, p107, p130, p300/CBP, p400, TRRAP, and CtBP were identified to be E1A-binding proteins and their roles in cellular transformation have been established. Although the major function of E1A is considered to be the regulation of gene expression that is critical for differentiation and cell cycle exit, one of the most significant questions relating to E1A transformation is how E1A mediates this regulation. RUNX3 is a transcription factor that was first described as a gastric cancer tumor suppressor but is now known to be involved in many different cancers. Exogenous expression of RUNX3 strongly inhibits the growth of cells. Here, we show that the adenovirus oncoprotein E1A interacts with RUNX3 in vitro and in vivo. RUNX3 interacts with the N-terminus (amino acids 2-29) of E1A, which is known to interact with p300/CBP, p400, and TRRAP. E1A interacts directly with the Runt domain of RUNX3 but does not interfere with CBFbeta-RUNX3 interactions. In addition, E1A inhibits the transactivation activity of RUNX3 on the p21(WAF1/CIP1) promoter. Consistent with these observations, the growth inhibition induced by RUNX3 is reduced by E1A. These results demonstrate that E1A specifically binds to RUNX3 and inactivates its transactivation activity. We propose that one of the mechanisms for the oncogenic activity of E1A is the inhibition of RUNX3, similar to that of RB and p300/CBP.
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Affiliation(s)
- Eun-Jeong Cha
- Department of Biochemistry, School of Medicine, Institute for Tumor Research, Chungbuk National University, Cheongju 361-763, South Korea
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Teufel DP, Freund SM, Bycroft M, Fersht AR. Four domains of p300 each bind tightly to a sequence spanning both transactivation subdomains of p53. Proc Natl Acad Sci U S A 2007; 104:7009-14. [PMID: 17438265 PMCID: PMC1855428 DOI: 10.1073/pnas.0702010104] [Citation(s) in RCA: 161] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The transcriptional coactivator p300 binds to and mediates the transcriptional functions of the tetrameric tumor suppressor p53. Both proteins consist of independently folded domains linked by intrinsically disordered sequences. A well studied short sequence of the p53 transactivation domain, p53(15-29), binds weakly to four folded domains of p300 [Taz1/cysteine-histidine-rich region 1 (CH1), Kix, Taz2/CH3, IBiD], with dissociation constants (K(D)) in the 100 muM region. However, we found that a longer N-terminal transactivation domain construct p53(1-57) bound tightly to each p300 domain. Taz2/CH3 had the greatest affinity (K(D) = 27 nM) and competes with the N-terminal domain of Mdm2 for the p53 N terminus. p300 thus can protect the N terminus of p53 against the binding of other proteins. Mutations of p53 that abrogate transactivation (L22Q/W23S, W53Q/F54S) greatly weakened binding to each p300 domain, linking phenotypic defects to weakened coactivator binding. We propose a complex between tetrameric p53 and p300 in which four domains of p300 wrap around the four transactivation domains of p53.
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Affiliation(s)
- Daniel P. Teufel
- MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road,Cambridge CB2 2QH, United Kingdom
| | - Stefan M. Freund
- MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road,Cambridge CB2 2QH, United Kingdom
| | - Mark Bycroft
- MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road,Cambridge CB2 2QH, United Kingdom
| | - Alan R. Fersht
- MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road,Cambridge CB2 2QH, United Kingdom
- *To whom correspondence should be addressed. E-mail:
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Zahedi K, Bissler JJ, Wang Z, Josyula A, Lu L, Diegelman P, Kisiel N, Porter CW, Soleimani M. Spermidine/spermine N1-acetyltransferase overexpression in kidney epithelial cells disrupts polyamine homeostasis, leads to DNA damage, and causes G2 arrest. Am J Physiol Cell Physiol 2007; 292:C1204-15. [PMID: 17065202 DOI: 10.1152/ajpcell.00451.2006] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Expression of spermidine/spermine N1-acetyltransferase (SSAT) increases in kidneys subjected to ischemia-reperfusion injury (IRI). Increased expression of SSAT in vitro leads to alterations in cellular polyamine content, depletion of cofactors and precursors of polyamine synthesis, and reduced cell proliferation. In our model system, a >28-fold increase in SSAT levels in HEK-293 cells leads to depletion of polyamines and elevation in the enzymatic activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase, suggestive of a compensatory reaction to increased polyamine catabolism. Increased expression of SSAT also led to DNA damage and G2 arrest. The increased DNA damage was primarily due to the depletion of polyamines. Other factors such as increased production of H2O2 due to polyamine oxidase activity may play a secondary role in the induction of DNA lesions. In response to DNA damage the ATM/ATR → Chk1/2 DNA repair and cell cycle checkpoint pathways were activated, mediating the G2 arrest in SSAT-expressing cells. In addition, the activation of ERK1 and ERK2, which play integral roles in the G2/M transition, is impaired in cells expressing SSAT. These results indicate that the disruption of polyamine homeostasis due to enhanced SSAT activity leads to DNA damage and reduced cell proliferation via activation of DNA repair and cell cycle checkpoint and disruption of Raf → MEK → ERK pathways. We propose that in kidneys subjected to IRI, one mechanism through which increased expression of SSAT may cause cellular injury and organ damage is through induction of DNA damage and the disruption of cell cycle.
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Affiliation(s)
- Kamyar Zahedi
- Division of Nephrology and Hypertension, Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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Felsani A, Mileo AM, Paggi MG. Retinoblastoma family proteins as key targets of the small DNA virus oncoproteins. Oncogene 2006; 25:5277-85. [PMID: 16936748 DOI: 10.1038/sj.onc.1209621] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
RB, the most investigated tumor suppressor gene, is the founder of the RB family of growth/tumor suppressors, which comprises also p107 (RBL1) and Rb2/p130 (RBL2). The protein products of these genes, pRb, p107 and pRb2/p130, respectively, are also known as 'pocket proteins', because they share a 'pocket' domain responsible for most of the functional interactions characterizing the activity of this family of cellular factors. The interest in these genes and proteins springs essentially from their ability to regulate negatively cell cycle processes and for their ability to slow down or abrogate neoplastic growth. The pocket domain of the RB family proteins is dramatically hampered in its functions by the interference of a number of proteins produced by the small DNA viruses. In the last two decades, the 'viral hypothesis' of cancer has received a considerable renewed impulse from the notion that small DNA viruses, such as Adenovirus, Human papillomavirus (HPV) and Polyomavirus, produce factors that can physically interact with major cellular regulators and alter their function. These viral proteins (oncoproteins) act as multifaceted molecular devices that have evolved to perform very specific tasks. Owing to these features, viral oncoproteins have been widely employed as invaluable experimental tools for the identification of several key families of regulators, particularly of the cell cycle homeostasis. Adenovirus early-region 1A (E1A) is the most widely investigated small DNA tumor virus oncoprotein, but relevant interest in human oncology is raised by the E1A-related E7 protein from transforming HPV strains and by Polyomavirus oncoproteins, particularly large and small T antigens from Simian virus 40, JC virus and BK virus.
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Affiliation(s)
- A Felsani
- Istituto di Neurobiologia e Medicina Molecolare, CNR, Rome, Italy
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Pomati F, Castiglioni S, Zuccato E, Fanelli R, Vigetti D, Rossetti C, Calamari D. Effects of a complex mixture of therapeutic drugs at environmental levels on human embryonic cells. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2006; 40:2442-7. [PMID: 16646487 DOI: 10.1021/es051715a] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The potential risk associated with the presence of low levels of pharmaceuticals in aquatic environments is currently under debate. In this study we investigated the effects of 13 drugs merged to mimic both the association and low concentration (ng/L) profiles detected in the environment. The mixture comprised atenolol, bezafibrate, carbamazepine, cyclophosphamide, ciprofloxacin, furosemide, hydrochlorothiazide, ibuprofen, lincomycin, ofloxacin, ranitidine, salbutamol, and sulfamethoxazole. At environmental exposure levels, the drug mix inhibited the growth of human embryonic cells HEK293, with the highest effect observed as a 30% decrease in cell proliferation compared to controls. Pharmaceuticals activated stress-response signaling protein kinases (ERK1/2), and induced overexpression of glutathione-S-transferase P1 gene. No evidence was found for apoptosis or necrosis in HEK293 cells, although morphological changes were observed. The drug mixture effectively stimulated the expression of cell-cycle progression-mediating genes p16 and p21, with a slight accumulation of cells in the G2/M phase of the cell-cycle. Our results suggest that a mixture of drugs at ng/L levels can inhibit cells proliferation by affecting their physiology and morphology. This also suggests that water-borne pharmaceuticals can be potential effectors on aquatic life.
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Affiliation(s)
- Francesco Pomati
- Department of Biotechnology and Molecular Sciences, University of Insubria, Varese 21100, Italy.
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Abstract
In response to various stresses, p53 is rapidly activated and transcriptionally regulates a number of target genes by which p53 modulates a variety of cellular activities. The transcriptional activity of p53 is delicately regulated by a plethora of cellular factors, independently or synergistically, in multiple ways in order to achieve a specific response. This article reviewed the role of the basal transcriptional machinery, co-activators, and co-repressors involved in p53-dependent transcription, and the underlying mechanism by which the p53 transcriptional activity is regulated. We also discussed some potentially interesting questions and future directions in the field.
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Affiliation(s)
- Gang Liu
- Department of Cell Biology, The University of Alabama at Birmingham, 1918 University Boulevard, Birmingham, AL 35294, USA
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Bahnassi AA, Zekri ARN, El-Houssini S, Mokhtar NM, Abdel-Aziz AO, Sherif GM, El-Mishad AM, Khaled HM. Hepatitis C virus-NS3P in relation to p53, p21waf, mdm2, p21-ras and c-erbB2 in hepatocarcinogenesis. J Gastroenterol Hepatol 2005; 20:1731-40. [PMID: 16246194 DOI: 10.1111/j.1440-1746.2005.04002.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND The non-structural protein 3 (NS3P) of hepatitis C virus (HCV) genome was linked to the neoplastic transformation of normal hepatocytes in chronically infected patients. However, the exact mechanisms involved in this process are unidentified yet, especially in the Egyptian population where the commonest type is genotype 4. METHODS We investigated 32 HCV reverse transcriptase-polymerase chain reaction (RT-PCR) positive hepatocellular carcinoma (HCC) cases and 18 morphologically normal hepatic tissues distant to tumors (MNT) for the correlation between HCV-NS3P, p53, p21(waf), mdm2, p21ras and c-erbB2 and DNA content by immunohistochemistry and image analysis. RESULTS The NS3P expression was lower in HCC (65.6%) than in MNT (94.4%) patients. The expression level of studied genes in HCC was: p53 (56.25%), p21(waf) (43.7%), mdm2 (59.4%), p21-ras (73.3%) and c-erbB2 (75%). Whereas in MNT, it was 22.2, 61.1, 44.4, 41.2 and 77.8%, respectively. The NS3P expression showed a significant correlation with the presence of cirrhosis, chronic active hepatitis (CAH) and tumor grade (P < 0.05). c-erbB2 overexpression and p21(waf) loss were higher in MNT than in HCC patients, however, this did not reach a statistically significant level. There was a statistically significant correlation between NS3P, c-erbB2 and p21(waf) (P < 0.01). There was also a significant correlation between p21(waf) loss and CAH (P = 0.01) as well as between mdm2, c-erbB2 and cirrhosis (P = 0.025 and 0.001) in HCC cases. There was a statistically significant difference in the ploidy status between HCC and MNT, but there was no significant relationship between the ploidy status and other clinicopathological features. CONCLUSION The carcinogenic effect of NS3P is probably exerted at an early stage of HCC possibly through a pathway involving c-erbB2 and p21(waf) alterations. In contrast, p53, p21ras and mdm2 alterations are late events in hepatocarcinogenesis and are usually associated with an aggressive phenotype.
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Affiliation(s)
- Abeer A Bahnassi
- Pathology Department, National Cancer Institute, Cairo University, Cairo, Egypt
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Yun S, Lie-A-Cheong C, Porter ACG. Discriminatory suppression of homologous recombination by p53. Nucleic Acids Res 2004; 32:6479-89. [PMID: 15601996 PMCID: PMC545454 DOI: 10.1093/nar/gkh986] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Revised: 11/19/2004] [Accepted: 11/19/2004] [Indexed: 12/19/2022] Open
Abstract
Homologous recombination (HR) is used in vertebrate somatic cells for essential, RAD51-dependent, repair of DNA double-strand-breaks (DSBs), but inappropriate HR can cause genome instability. A transcriptional transactivation-independent role for p53 in suppressing HR has been established, but is not detected in all HR assays. To address the basis of such exceptions, and the possibility that suppression by p53 may be discriminatory, we have conducted a controlled comparison of the effects of p53 depletion on three different kinds of HR. We show that, within the same cells, p53 depletion promotes both intra-chromosomal HR (ICHR) and extra-chromosomal HR (ECHR), but not homologous DNA integration (gene targeting; GT). This conclusion holds true for both spontaneous and DSB-induced ICHR and GT. We show further that non-conservative ICHR is more susceptible than conservative ICHR to inhibition by p53. These results provide strong evidence that p53 can discriminate between different forms of HR and, despite the fact that GT is used experimentally for gene disruption, is consistent with the possibility that p53 preferentially suppresses genome-destabilizing forms of HR. While the mechanism of suppression by p53 remains unclear, our data suggest that it is independent of mismatch repair and of changes in RAD51 protein levels.
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Affiliation(s)
- Sheng Yun
- Gene Targeting Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Du Cane Road, London W12 ONN, UK
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Kühnel F, Zender L, Wirth T, Schulte B, Trautwein C, Manns M, Kubicka S. Tumor-specific adenoviral gene therapy: transcriptional repression of gene expression by utilizing p53-signal transduction pathways. Cancer Gene Ther 2004; 11:28-40. [PMID: 14681724 DOI: 10.1038/sj.cgt.7700632] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Adenoviral gene expression that is repressed by p53 in nontransformed cells could provide a tumor-specific gene therapy approach for a large subset of tumors. Adenoviral infection in vivo induces stabilization of p53, which can be utilized for a strategy that includes p53-dependent expression of a transcriptional repressor and a target promoter,which is highly susceptible for transcriptional repression. Therefore, we constructed different versions of CMV-promoters (CMVgal) with binding sites for GAL4-DBD and investigated 11 GAL4-DBD fusion proteins to elucidate the most effective repressor domain to silence CMVgal activity. The transcriptional repressor GAL4-KRAB-A under control of a p53-dependent promoter facilitates strong CMVgal-mediated gene expression specifically in p53 mutant cells by a double-recombinant adenoviral vector (Ad-RGCdR). GAL4-KRAB-A mediates strong transcriptional repression of Ad-RGCdR in p53 wild-type cells, which could be further enhanced by preactivation of p53-signalling following low-dose chemotherapy prior to adenoviral infection. By utilizing p53 signalling involved in chemotherapy and adenoviral infection, more than 99% of Ad-RGCdR gene expression could be repressed in p53 wild-type cells. Controlled gene expression from CMVgal promoters by transcriptional repression utilizing functional p53 signalling thus provides a very effective tool for tumor-specific adenoviral gene therapy.
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Affiliation(s)
- Florian Kühnel
- Department of Gastroenterology, Hepatology and Endocrinology, Medical School Hannover, Carl Neuberg Str. 1, 30625 Hannover, Germany
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Zhao LY, Colosimo AL, Liu Y, Wan Y, Liao D. Adenovirus E1B 55-kilodalton oncoprotein binds to Daxx and eliminates enhancement of p53-dependent transcription by Daxx. J Virol 2003; 77:11809-21. [PMID: 14557665 PMCID: PMC229361 DOI: 10.1128/jvi.77.21.11809-11821.2003] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The adenovirus E1B 55-kDa protein impairs the p53 pathway and enhances transformation, although the underlying mechanisms remain to be defined. We found that Daxx binds to the E1B 55-kDa protein in a yeast two-hybrid screen. The two proteins interact through their C termini. Mutation of three potential phosphorylation sites (S489/490 and T494 to alanine) within the E1B 55-kDa protein did not affect its interaction with Daxx, although such mutations were previously shown to inhibit E1B's ability to repress p53-dependent transcription and to enhance transformation. In addition to their coimmunoprecipitation in 293 extracts, purified Daxx interacted with the E1B 55-kDa protein in vitro, indicating their direct interaction. In 293 cells, Daxx colocalized with the E1B 55-kDa protein within discrete nuclear dots, where p53 was also found. Such structures were distinct from PML (promyelocytic leukemia protein) bodies, and it appeared that Daxx was displaced from PML bodies. Thus, the Daxx concentration was diminished in dots with a prominent presence of PML and vice versa. Indeed, PML overexpression led to dramatic redistribution of Daxx from p53-E1B 55-kDa protein complexes to PML bodies. Additionally, expression of the E1B 55-kDa protein in Saos2 osteosarcoma cells reduced the number of PML bodies. Our data suggest that E1B and PML compete for available Daxx in the cell. Surprisingly, Daxx significantly augmented p53-mediated transcription and the E1B 55-kDa protein eliminated this effect. Thus, it is likely that the E1B 55-kDa protein sequesters Daxx and p53 in specific nuclear locations, where p53 cannot activate transcription. One consequence of the Daxx-E1B interaction might be an alteration of normal interactions of Daxx, PML, and p53, which may contribute to cell transformation.
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Affiliation(s)
- Lisa Y Zhao
- Department of Anatomy and Cell Biology and Shands Cancer Center, University of Florida College of Medicine, Gainesville, Florida 32610-0235, USA
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27
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Das S, El-Deiry WS, Somasundaram K. Regulation of the p53 homolog p73 by adenoviral oncogene E1A. J Biol Chem 2003; 278:18313-20. [PMID: 12639967 DOI: 10.1074/jbc.m211704200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
p73 is a p53 homolog, as they are similar structurally and functionally. Unlike p53, p73 is not inactivated by the products of viral oncogenes such as SV40 T antigen and human papilloma virus E6. Here we show that the product of adenoviral oncogene E1A inhibits the transcriptional activation by both p73alpha and p73beta. Electrophoretic mobility shift assays revealed that E1A does not inhibit the sequence-specific DNA binding by p73. Transcriptional activation by a fusion protein containing the Gal4 DNA-binding domain and either of the activation domains of p73 was inhibited by wild-type (WT) E1A, but not by the N-terminal deletion mutant E1A(Delta2-36). E1A(Delta2-36), which does not bind to the p300/CBP family of coactivators, failed to inhibit p73-mediated transcription, whereas E1A(DeltaCR2), a deletion mutant that does not bind to the pRb family of proteins, inhibited p73-mediated transcription as efficiently as WT E1A. Consistent with these observations, growth arrest induced by p73 expressed from a recombinant adenovirus was abrogated by WT E1A, which correlated with inhibition of p73-mediated induction of p21(WAF1/CIP1) by E1A. However, p73 was able to induce p21(WAF1/CIP1) and to mediate growth arrest in the presence of E1A(Delta2-36). Furthermore, the expression of either wild-type E1A or E1A(Delta2-36) resulted in the stabilization of endogenous p73. However, p73 stabilized in response to the expression of E1A(Delta2-36), but not WT E1A, was able to activate the expression of p21(WAF1/CIP1). These results suggest that the transcriptional activation function of p73 is specifically targeted by E1A through a mechanism involving p300/CBP proteins during the process of transformation and that p73 may have a role to play as a tumor suppressor.
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Affiliation(s)
- Sanjeev Das
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
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28
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Abstract
OBJECTIVES [corrected] Genomic instability is a driving force for tumorigenesis. Telomerase and p53 play central roles in maintaining genomic integrity. The purpose of this study was to assess the role of telomerase expression and p53 protein overexpression in hepatocellular carcinoma (HCC). METHODS Telomerase activity and p53 overexpression were investigated in 63 patients undergoing hepatectomy for HCC by a telomeric repeat amplification protocol and immunohistochemistry, respectively. The associations among telomerase expression, p53 overexpression, and clinicopathological features were analyzed, and independent prognostic factors in the recurrence of HCC after hepatectomy were determined. RESULTS Telomerase expression did not correlate with clinicopathological features except hepatitis virus status (p = 0.04) and was identified as a significant prognostic variable for HCC recurrence (p = 0.027) along with portal venous invasion (p = 0.001). In contrast, p53 overexpression strongly correlated with tumor differentiation (p < 0.0001) but did not reflect time to recurrence (p = 0.26). Telomerase expression did not correlate with p53 overexpression (p = 0.35). CONCLUSIONS The reactivation of telomerase was of significant value in predicting the recurrence of HCC after hepatectomy. However, p53 overexpression did not correlate with telomerase expression in HCC, nor did it reflect the time to recurrence.
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Affiliation(s)
- Takashi Kobayashi
- Hepato-Biliary-Pancreatic Surgery Division, Department of Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
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29
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Sauthoff H, Pipiya T, Heitner S, Chen S, Norman RG, Rom WN, Hay JG. Late expression of p53 from a replicating adenovirus improves tumor cell killing and is more tumor cell specific than expression of the adenoviral death protein. Hum Gene Ther 2002; 13:1859-71. [PMID: 12396618 DOI: 10.1089/104303402760372954] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Gene transfer of p53 induces cell death in most cancer cells, and replication-defective adenoviral vectors expressing p53 are being evaluated in clinical trials. However, low transduction efficiency limits the efficacy of replication-defective vector systems for cancer therapy. The use of replication-competent vectors for gene delivery may have several advantages, holding the potential to multiply and spread the therapeutic agent after infection of only a few cells. However, expression of a transgene may adversely affect viral replication. We have constructed a replicating adenoviral vector (Adp53rc) that expresses high levels of p53 at a late time point in the viral life cycle and also contains a deletion of the adenoviral death protein (ADP). Adp53rc-infected cancer cells demonstrated high levels of p53 expression in parallel with the late expression pattern of the adenoviral fiber protein. p53 expression late in the viral life cycle did not impair effective virus propagation. Survival of several lung cancer cell lines was significantly diminished after infection with Adp53rc, compared with an identical p53-negative control virus. p53 expression also improved virus release and spread. Interestingly, p53 was more cytotoxic than the ADP in cancer cells but less cytotoxic than the ADP in normal cells. In conclusion, late expression of p53 from a replicating virus improves tumor cell killing and viral spread without impairing viral replication. In addition, in combination with a deletion of the ADP, specificity of tumor cell killing is improved.
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Affiliation(s)
- Harald Sauthoff
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
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30
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Abstract
The adenovirus early region 1A (E1A) proteins were described originally as immortalizing oncoproteins that altered transcription in rodent cells. Surprisingly, the 243-amino-acid form of adenovirus-5 E1A was found subsequently to reverse-transform many human tumour cells. Tumour suppression apparently results from the ability of E1A to re-programme transcription in tumour cells, and the molecular basis of this intriguing effect is now beginning to emerge. These discoveries have provided a tool with which to study the regulation of fundamental cellular processes.
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Affiliation(s)
- Steven M Frisch
- The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA.
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31
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Yu Q, Rose JH, Zhang H, Pommier Y. Antisense inhibition of Chk2/hCds1 expression attenuates DNA damage-induced S and G2 checkpoints and enhances apoptotic activity in HEK-293 cells. FEBS Lett 2001; 505:7-12. [PMID: 11557032 DOI: 10.1016/s0014-5793(01)02756-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The cellular response to DNA damage involves checkpoint controls that delay cell cycle progression in order to provide time for repair of damaged DNA. Chk2/hCds1 is a recently identified homolog of the yeast Cds1 kinase that is involved in cell cycle checkpoint response to DNA damage. To investigate the functions of Chk2/hCds1 in response to DNA damage in mammalian cells, we established a stable human kidney embryonic cell line (HEK-293) that expresses antisense Chk2/hCds1 (Chk2AS) under the control of an inducible promoter. Cells that express Chk2AS display defective S-phase delay in response to DNA replication-mediated DNA damage induced by the topoisomerase I inhibitor camptothecin. The defective G2 checkpoint was also observed in Chk2AS cells exposed to the DNA damaging agent VP-16 or gamma-radiation. Enhanced apoptosis was observed in Chk2AS cells after exposure to gamma-radiation or camptothecin. No p53 activation was observed after DNA damage in HEK-293 or Chk2AS cells. Our results indicate that perturbation of Chk2/hCds1 expression adversely affects the S- and G2-phase checkpoints following DNA damage or DNA replication block, and suggest that reduced expression of Chk2/hCds1 might promote a p53-independent apoptotic response.
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Affiliation(s)
- Q Yu
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bldg. 37, Rm. 4E28, Bethesda, MD 20892-4255, USA
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32
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Zhao J, Wang H, Wei L, Habib NA, Lu X, Wu M, Guo Y. The cytotoxic effect of E1B 55-kDa mutant adenovirus on human hepatocellular carcinoma cell lines. Cancer Gene Ther 2001; 8:333-41. [PMID: 11477453 DOI: 10.1038/sj.cgt.7700316] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2001] [Indexed: 11/09/2022]
Abstract
It has been suggested the E1B 55 kDa mutant adenovirus dl1520 can selectively kill p53-deficient human tumor cells. In this study, we examined the cytotoxic effect of dl1520 on nine human hepatocellular carcinoma (HCC) cell lines with different p53 genetic and functional status. The results showed that HCC cell lines with deleted or mutant p53 gene and reduced p53 transcriptional activities were more susceptible to dl1520-induced cytolysis. Hep3B (p53-null) and HepG2 (p53-wt) cells were arrested at G2/M phase when cytolysis occurred. Cyclin-dependent kinase inhibitor (CDKI) p21(Waf-1/Cip-1) was downregulated 24 hours after dl1520 infection in HepG2 cells and increased when cytolysis occurred. No p21 expression was detected in Hep3B cells. DNA fragmentation was found in both Hep3B and HepG2 cells after dl1520 infection. Bax expression increased in dl1520-infected HepG2 cells but not in Hep3B cells. Notably, three Bax-like proteins, molecular mass around 40 to 80 kDa, accumulated 48 hours after adenovirus infection in Hep3B cells but not in HepG2 cells. These results suggest that the susceptibility of HCC cells to dl1520-induced cytolysis is related to both p53 genotype and functional status, and is mediated by both cell cycle disturbance and apoptosis.
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Affiliation(s)
- J Zhao
- International Cancer Institute and Eastern Hospital of Hepatobiliary Surgery, the Second Military Medical University, Shanghai 200433, People's Republic of China
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33
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Grossman SR. p300/CBP/p53 interaction and regulation of the p53 response. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:2773-8. [PMID: 11358491 DOI: 10.1046/j.1432-1327.2001.02226.x] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Substantial evidence points to a critical role for the p300/CREB binding protein (CBP) coactivators in p53 responses to DNA damage. p300/CBP and the associated protein P/CAF bind to and acetylate p53 during the DNA damage response, and are needed for full p53 transactivation as well as downstream p53 effects of growth arrest and/or apoptosis. Beyond this simplistic model, p300/CBP appear to be complex integrators of signals that regulate p53, and biochemically, the multipartite p53/p300/CBP interaction is equally complex. Through physical interaction with p53, p300/CBP can both positively and negatively regulate p53 transactivation, as well as p53 protein turnover depending on cellular context and environmental stimuli, such as DNA damage.
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Affiliation(s)
- S R Grossman
- Department of Adult Oncology and Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
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34
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Abstract
According to classical concepts of viral oncogenesis, the persistence of virus-specific oncogenes is required to maintain the transformed cellular phenotype. In contrast, the "hit-and-run" hypothesis claims that viruses can mediate cellular transformation through an initial "hit," while maintenance of the transformed state is compatible with the loss ("run") of viral molecules. It is well established that the adenovirus E1A and E1B gene products can cooperatively transform primary human and rodent cells to a tumorigenic phenotype and that these cells permanently express the viral oncogenes. Additionally, recent studies have shown that the adenovirus E4 region encodes two novel oncoproteins, the products of E4orf6 and E4orf3, which cooperate with the viral E1A proteins to transform primary rat cells in an E1B-like fashion. Unexpectedly, however, cells transformed by E1A and either E4orf6 or E4orf3 fail to express the viral E4 gene products, and only a subset contain E1A proteins. In fact, the majority of these cells lack E4- and E1A-specific DNA sequences, indicating that transformation occurred through a hit-and-run mechanism. We provide evidence that the unusual transforming activities of the adenoviral oncoproteins may be due to their mutagenic potential. Our results strongly support the possibility that even tumors that lack any detectable virus-specific molecules can be of viral origin, which could have a significant impact on the use of adenoviral vectors for gene therapy.
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Affiliation(s)
- M Nevels
- Institut für Medizinische Mikrobiologie und Hygiene, Universität Regensburg, D-93053 Regensburg, Germany
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35
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Park JS, Kim EJ, Lee JY, Sin HS, Namkoong SE, Um SJ. Functional inactivation of p73, a homolog of p53 tumor suppressor protein, by human papillomavirus E6 proteins. Int J Cancer 2001; 91:822-7. [PMID: 11275986 DOI: 10.1002/1097-0215(200002)9999:9999<::aid-ijc1130>3.0.co;2-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Human papillomavirus (HPV) is strongly implicated as a causative agent in the etiology of cervical cancer. Of its gene products, E6 binds to and inactivates p53 tumor suppressor protein by ubiquitin/proteasome-dependent degradation. Recently, p73, a novel family of p53, has been identified and demonstrated, like p53, to activate p21(WAF1). Here we show that p73 is also inactivated by HPV-E6, but ubiquitin-mediated proteolysis is not responsive. Yeast two-hybrid and GST pull-down assays indicate a physical interaction between p73 and either HPV-16 or HPV-11 E6 proteins in vivo and in vitro, respectively. The transactivation domain (amino acid residues 1 to 49) is found to be absolutely required for the interaction. Transient co-expression of E6 significantly inhibits the p73-mdiated activation of p21(WAF1) promoter in a p53-defective C33A cell line. Using Gal4-p73 fusion protein, we demonstrate that E6 inhibition of p73 transactivation function is independent of sequence-specific DNA binding, which is confirmed by a direct electrophoretic mobility shift assay. Moreover, E6 inhibits p73 function by interfering with the activity of the amino-terminal activation domain. Co-transfection of E6 mutants reveals that the same portion of E6 appears to be responsible for the inactivation of p53 and p73 function. However, the inactivation mechanism of p73 is clearly different from that of p53, because p73, unlike p53, is inactivated by both high- and low-risk E6s and is not susceptible to E6-dependent proteolysis. These overall results, consequently, suggest that in addition to the inactivation of p53, the functional interference of p73 by HPV-E6 may, at least in part, contribute to E6-mediated transformation and hyperproliferation of cervical cells.
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Affiliation(s)
- J S Park
- Department of Obstetrics and Gynecology, Catholic University Medical College, Seoul, Korea
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36
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Park JS, Kim EJ, Lee JY, Sin HS, Namkoong SE, Um SJ. Functional inactivation of p73, a homolog of p53 tumor suppressor protein, by human papillomavirus E6 proteins. Int J Cancer 2001. [DOI: 10.1002/1097-0215(200002)9999:9999%3c::aid-ijc1130%3e3.0.co;2-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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37
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Liu Y, Colosimo AL, Yang XJ, Liao D. Adenovirus E1B 55-kilodalton oncoprotein inhibits p53 acetylation by PCAF. Mol Cell Biol 2000; 20:5540-53. [PMID: 10891493 PMCID: PMC86007 DOI: 10.1128/mcb.20.15.5540-5553.2000] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The adenovirus E1B 55-kDa protein binds to cellular tumor suppressor p53 and inactivates its transcriptional transactivation function. p53 transactivation activity is dependent upon its ability to bind to specific DNA sequences near the promoters of its target genes. It was shown recently that p53 is acetylated by transcriptional coactivators p300, CREB bidning protein (CBP), and PCAF and that acetylation of p53 by these proteins enhances p53 sequence-specific DNA binding. Here we show that the E1B 55-kDa protein specifically inhibits p53 acetylation by PCAF in vivo and in vitro, while acetylation of histones and PCAF autoacetylation is not affected. Furthermore, the DNA-binding activity of p53 is diminished in cells expressing the E1B 55-kDa protein. PCAF binds to the E1B 55-kDa protein and to a region near the C terminus of p53 encompassing Lys-320, the specific PCAF acetylation site. We further show that the E1B 55-kDa protein interferes with the physical interaction between PCAF and p53, suggesting that the E1B 55-kDa protein inhibits PCAF acetylase function on p53 by preventing enzyme-substrate interaction. These results underscore the importance of p53 acetylation for its function and suggest that inhibition of p53 acetylation by viral oncoproteins prevent its activation, thereby contributing to viral transformation.
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Affiliation(s)
- Y Liu
- Department of Microbiology and Infectious Diseases, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
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38
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Shi YZ, Hui AM, Takayama T, Li X, Cui X, Makuuchi M. Reduced p21(WAF1/CIP1) protein expression is predominantly related to altered p53 in hepatocellular carcinomas. Br J Cancer 2000; 83:50-5. [PMID: 10883667 PMCID: PMC2374549 DOI: 10.1054/bjoc.2000.1310] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
To investigate the relationship between the expression of p21(WAF1/CIP1) protein and p53 status and the possible role of the two proteins in hepatocellular carcinomas (HCCs), we examined the expression of p21(WAF1/CIP1) and p53 immunohistochemically in 81 tumours from 65 patients with hepatocellular carcinoma. p21(WAF1/CIP1) protein was absent from 59 of 81 tumours (72.8%), and altered p53 expression was found in 43 (53.1%). p21(WAF1/CIP1) expression was significantly associated with p53 status (P = 0.0008); 38 of 59 tumours lacking p21(WAF1/CIP1) protein were accompanied by altered p53 expression. Further analyses showed that p21(WAF1/CIP1) expression was inversely correlated with p53 expression in hepatitis C virus (HCV)-related HCCs, but not in HBV-related hepatocellular carcinomas and hepatocellular carcinomas without viral infection. All 11 tumours with intrahepatic metastasis showed altered p21(WAF1/CIP1) or p53 expression. In contrast, no intrahepatic metastasis was found in any of the 17 tumours without abnormal expression of either of the two proteins. These results suggest that: (1) different modes of p21(WAF1/CIP1) regulation are involved in HCCs differing in their hepatitis viral infection status, and p21(WAF1/CIP1) expression appears to be predominantly related to altered p53 in HCV-related HCCs; (2) disruption of the p53-p21(WAF1/CIP1) cell-cycle-regulating pathway may contribute to malignant progression of HCC.
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Affiliation(s)
- Y Z Shi
- Department of Surgery, Graduate School of Medicine, University of Tokyo, Japan
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39
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Brick DJ, Burke RD, Minkley AA, Upton C. Ectromelia virus virulence factor p28 acts upstream of caspase-3 in response to UV light-induced apoptosis. J Gen Virol 2000; 81:1087-97. [PMID: 10725436 DOI: 10.1099/0022-1317-81-4-1087] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Ectromelia virus (EV) virulence factor p28 (EVp28) is a member of a family of poxvirus proteins that are defined largely by the presence of a C-terminal RING finger motif and localization to virus factories within the cytoplasm of infected cells. Previously, overexpression of the Shope fibroma virus (SFV) homologue, N1R, in vaccinia virus (VV)-infected BGMK cells was found to inhibit virus-induced apoptosis. Here, we report that both EVp28 and overexpression of SFV N1R in poxvirus-infected HeLa cells protect specifically from UV light-induced apoptosis, but not from apoptosis induced by Fas or TNF. Further, we report that both VV and EV protect from apoptosis induced by UV, Fas and TNF. Immunoblot analysis indicates that EVp28 acts upstream of caspase-3, blocking activation of the protease in response to UV irradiation. Although no difference was found in replication of an EVp28(-) mutant virus, which expresses a truncated p28 protein lacking the RING motif, compared to EV wild-type in HeLa cells, UV irradiation of infected HeLa cells reduced the replication of the EV mutant compared with wild-type EV.
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Affiliation(s)
- D J Brick
- Departments of Biochemistry and Microbiology and Biology, University of Victoria, PO Box 3055, Victoria, BC, Canada V8W 3P6
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40
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Kannabiran C, Morris GF, Mathews MB. Dual action of the adenovirus E1A 243R oncoprotein on the human proliferating cell nuclear antigen promoter: repression of transcriptional activation by p53. Oncogene 1999; 18:7825-33. [PMID: 10618724 DOI: 10.1038/sj.onc.1203294] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The promoter of the human proliferating cell nuclear antigen (PCNA) gene is activated by the adenovirus oncoprotein E1A 243R in HeLa cells. To understand the effect of this oncoprotein on PCNA expression in cells that are sensitive to oncogenic transformation by adenovirus, we studied the effect of E1A 243R on PCNA promoter-directed reporter gene expression in cloned rat embryo fibroblast (CREF) and primary baby rat kidney cells. In contrast to the results obtained in HeLa cells, E1A repressed the PCNA promoter in both cell-types. Promoter analysis identified a p53-responsive element that mediates E1A-induced repression. Repression required the intact N-terminus of E1A 243R, as shown by the ability of mutant E1A proteins to repress the promoter, and correlated with the p300-binding region of E1A. The adenovirus E1B 19K protein relieved repression by E1A 243R. These results reveal dual pathways for induction of this essential DNA replication factor and suggest a mechanism for oncogenic cooperativity between the E1A and E1B oncoproteins.
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Affiliation(s)
- C Kannabiran
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY 11724, USA
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41
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Abstract
Activation of p53 can occur in response to a number of cellular stresses, including DNA damage, hypoxia and nucleotide deprivation. Several forms of DNA damage have been shown to activate p53, including those generated by ionising radiation (IR), radio-mimetic drugs, ultraviolet light (UV) and chemicals such as methyl methane sulfonate (MMS). Under normal conditions, p53 levels are maintained at a low state by virtue of the extremely short-half life of the polypeptide. In addition to this, p53 normally exists in an largely inactive state that is relatively inefficient at binding to DNA and activating transcription. Activation of p53 in response to DNA damage is associated with a rapid increase in its levels and with an increased ability of p53 to bind DNA and mediate transcriptional activation. This then leads to the activation of a number of genes whose products trigger cell-cycle arrest, apoptosis, or DNA repair. Recent work has suggested that this regulation is brought about largely through DNA damage triggering a series of phosphorylation, de-phosphorylation and acetylation events on the p53 polypeptide. Here, we discuss the nature of these modifications, the enzymes that bring them about, and how changes in p53 modification lead to p53 activation.
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Affiliation(s)
- N D Lakin
- Wellcome Trust/Cancer Research Campaign, Institute of Cancer and Developmental Biology, Cambridge University, Tennis Court Road, Cambridge CB2 1QR, UK
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42
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Steegenga WT, Riteco N, Bos JL. Infectivity and expression of the early adenovirus proteins are important regulators of wild-type and DeltaE1B adenovirus replication in human cells. Oncogene 1999; 18:5032-43. [PMID: 10490840 DOI: 10.1038/sj.onc.1202886] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
An adenovirus mutant lacking the expression of the large E1B protein (DeltaE1B) has been reported to replicate selectively in cells lacking the expression of functionally wild-type (wt) p53. Based on these results the DeltaE1B or ONYX-015 virus has been proposed to be an oncolytic virus which might be useful to treat p53-deficient tumors. Recently however, contradictory results have been published indicating that p53-dependent cell death is required for productive adenovirus infection. Since there is an urgent need for new methods to treat aggressive, mutant p53-expressing primary tumors and their metastases we carefully examined adenovirus replication in human cells to determine whether or not the DeltaE1B virus can be used for tumor therapy. The results we present here show that not all human tumor cell lines take up adenovirus efficiently. In addition, we observed inhibition of the expression of adenovirus early proteins in tumor cells. We present evidence that these two factors rather than the p53 status of the cell determine whether adenovirus infection results in lytic cell death. Furthermore, the results we obtained by infecting a panel of different tumor cell lines show that viral spread of the DeltaE1B is strongly inhibited in almost all p53-proficient and -deficient cell lines compared to the wt virus. We conclude that the efficiency of the DeltaE1B virus to replicate efficiently in tumor cells is determined by the ability to infect cells and to express the early adenovirus proteins rather than the status of p53.
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Affiliation(s)
- W T Steegenga
- Laboratory for Physiological Chemistry and Centre for Biomedical Genetics, Utrecht University, 3508 TA Utrecht, The Netherlands
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43
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Goodrum FD, Ornelles DA. Roles for the E4 orf6, orf3, and E1B 55-kilodalton proteins in cell cycle-independent adenovirus replication. J Virol 1999; 73:7474-88. [PMID: 10438837 PMCID: PMC104274 DOI: 10.1128/jvi.73.9.7474-7488.1999] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adenoviruses bearing lesions in the E1B 55-kDa protein (E1B 55-kDa) gene are restricted by the cell cycle such that mutant virus growth is most impaired in cells infected during G(1) and least restricted in cells infected during S phase (F. D. Goodrum and D. A. Ornelles, J. Virol. 71:548-561, 1997). A similar defect is reported here for E4 orf6-mutant viruses. An E4 orf3-mutant virus was not restricted for growth by the cell cycle. However, orf3 was required for enhanced growth of an E4 orf6-mutant virus in cells infected during S phase. The cell cycle restriction may be linked to virus-mediated mRNA transport because both E1B 55-kDa- and E4 orf6-mutant viruses are defective at regulating mRNA transport at late times of infection. Accordingly, the cytoplasmic-to-nuclear ratio of late viral mRNA was reduced in G(1) cells infected with the mutant viruses compared to that in G(1) cells infected with the wild-type virus. By contrast, this ratio was equivalent among cells infected during S phase with the wild-type or mutant viruses. Furthermore, cells infected during S phase with the E1B 55-kDa- or E4 orf6-mutant viruses synthesized more late viral protein than did cells infected during G(1). However, the total amount of cytoplasmic late viral mRNA was greater in cells infected during G(1) than in cells infected during S phase with either the wild-type or mutant viruses, indicating that enhanced transport of viral mRNA in cells infected during S phase cannot account for the difference in yields in cells infected during S phase and in cells infected during G(1). Thus, additional factors affect the cell cycle restriction. These results indicate that the E4 orf6 and orf3 proteins, in addition to the E1B 55-kDa protein, may cooperate to promote cell cycle-independent adenovirus growth.
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Affiliation(s)
- F D Goodrum
- Molecular Genetics Program and Department of Microbiology and Immunology, Wake Forest University School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157-1064, USA
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44
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Gottifredi V, Peschiaroli A, Fimia GM, Maione R. p53-independent apoptosis induced by muscle differentiation stimuli in polyomavirus large T-expressing myoblasts. J Cell Sci 1999; 112 ( Pt 14):2397-407. [PMID: 10381395 DOI: 10.1242/jcs.112.14.2397] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Abnormal proliferation signals, driven by cellular or viral oncogenes, can result in the induction of apoptosis under sub-optimal cell growth conditions. The tumor suppressor p53 plays a central role in mediating oncogene-induced apoptosis, therefore transformed cells lacking p53 are generally resistant to apoptosis-promoting treatments. In a previous work we have reported that the expression of polyomavirus large T antigen causes apoptosis in differentiating myoblasts and that this phenomenon is dependent on the onset of muscle differentiation in the absence of a correct cell cycle arrest. Here we report that polyomavirus large T increases the levels and activity of p53, but these alterations are not involved in the apoptotic mechanism. Apoptosis in polyomavirus large T-expressing myoblasts is not prevented by the expression of a p53 dominant-negative mutant nor it is increased by p53 over-expression. Moreover, forced differentiation induced through the over-expression of the muscle regulatory factor MyoD, leads to apoptosis without altering p53 function and, more significantly, even in a p53-null background. Our results indicate that apoptosis induced by the activation of muscle differentiation pathways in oncogene-expressing cells can occur in a p53-independent manner.
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Affiliation(s)
- V Gottifredi
- Isituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biotecnologie Cellulari ed Ematologia, Sezione di Genetica Molecolare, Università di Roma La Sapienza, Viale Regina Elena 324, Italy
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Steegenga WT, Shvarts A, Riteco N, Bos JL, Jochemsen AG. Distinct regulation of p53 and p73 activity by adenovirus E1A, E1B, and E4orf6 proteins. Mol Cell Biol 1999; 19:3885-94. [PMID: 10207112 PMCID: PMC84246 DOI: 10.1128/mcb.19.5.3885] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multiple adenovirus (Ad) early proteins have been shown to inhibit transcription activation by p53 and thereby to alter its normal biological functioning. Since these Ad proteins affect the activity of p53 via different mechanisms, we examined whether this inhibition is target gene specific. In addition, we analyzed whether the same Ad early proteins have a comparable effect on transcription activation by the recently identified p53 homologue p73. Our results show that the large E1B proteins very efficiently inhibited the activity of p53 on the Bax, p21(Waf1), cyclin G, and MDM2 reporter constructs but had no effect on the activation of the same reporter constructs by p73, with the exception of some inhibition of the Bax promoter by Ad12 E1B. The repressive effect of the E1A proteins on p53 activity is less than that seen with the large E1B proteins, but the E1A proteins inhibit the activity of both p53 and p73. We could not detect significant inhibition of p53 functions by E4orf6, but a clear repression of the transcription activation by p73 by this Ad early protein was observed. In addition, we found that stable expression of the Ad5 E1A and that of the E1B protein both caused increased p73 protein expression. The large E1B and the E4orf6 proteins together do not target the p73 protein for rapid degradation after adenoviral infection, as has previously been found for the p53 protein, probably because the large E1B protein does not interact with p73. Our results suggest that the p53 and p73 proteins are both inactivated after Ad infection and transformation but via distinct mechanisms.
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Affiliation(s)
- W T Steegenga
- Laboratory for Physiological Chemistry and Centre for Biomedical Genetics, Utrecht University, 3508 TA Utrecht, The Netherlands.
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Xu J, Morris GF. p53-mediated regulation of proliferating cell nuclear antigen expression in cells exposed to ionizing radiation. Mol Cell Biol 1999; 19:12-20. [PMID: 9858527 PMCID: PMC83861 DOI: 10.1128/mcb.19.1.12] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/1998] [Accepted: 09/18/1998] [Indexed: 11/20/2022] Open
Abstract
The proliferating cell nuclear antigen (PCNA) is a highly conserved cellular protein that functions both in DNA replication and in DNA repair. Exposure of a rat embryo fibroblast cell line (CREF cells) to gamma radiation induced simultaneous expression of PCNA with the p53 tumor suppressor protein and the cyclin-dependent kinase inhibitor p21(WAF1/Cip1). PCNA mRNA levels transiently increased in serum-starved cells exposed to ionizing radiation, an observation suggesting that the radiation-associated increase in PCNA expression could be dissociated from cell cycle progression. Irradiation of CREF cells activated a transiently expressed PCNA promoter chloramphenicol acetyltransferase construct through p53 binding sequences via a mechanism blocked by a dominant negative mutant p53. Electrophoretic mobility shift assays with nuclear extracts prepared from irradiated CREF cells produced four p53-specific DNA-protein complexes with the PCNA p53 binding site. Addition of monoclonal antibody PAb421 (p53-specific) or AC238 (specific to the transcriptional coactivator p300/CREB binding protein) to the mobility shift assay distinguished different forms of p53 that changed in relative abundance with time after irradiation. These findings suggest a complex cellular response to DNA damage in which p53 transiently activates expression of PCNA for the purpose of limited DNA repair. In a population of nongrowing cells with diminished PCNA levels, this pathway may be crucial to survival following DNA damage.
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Affiliation(s)
- J Xu
- Programs in Molecular and Cellular Biology and Lung Biology, Department of Pathology, Tulane Cancer Center and Tulane/Xavier Center for Bioenvironmental Research, New Orleans, Louisiana 70112, USA
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Giaccia AJ, Kastan MB. The complexity of p53 modulation: emerging patterns from divergent signals. Genes Dev 1998; 12:2973-83. [PMID: 9765199 DOI: 10.1101/gad.12.19.2973] [Citation(s) in RCA: 984] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- A J Giaccia
- Mayer Cancer Biology Research Laboratory, Department of Radiation Oncology, Stanford University, Stanford, California 94305-5468, USA
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Karuppayil SM, Moran E, Das GM. Differential regulation of p53-dependent and -independent proliferating cell nuclear antigen gene transcription by 12 S E1A oncoprotein requires CBP. J Biol Chem 1998; 273:17303-6. [PMID: 9651310 DOI: 10.1074/jbc.273.28.17303] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The tumor suppressor protein p53 and the adenoviral 12 S E1A oncoprotein are both known to elicit their biological effects mainly by regulating the transcription of important cellular genes. The human proliferating cell nuclear antigen (PCNA) gene is a transcriptional target of both p53 and E1A. We have analyzed the effects of p53 and 12 S E1A, separately as well as together, on PCNA gene transcription. Our results showed that whereas both p53 and 12 S E1A separately activated PCNA transcription, 12 S E1A repressed p53-mediated transcriptional activation. Thus, 12 S E1A uses a dual strategy of transcriptional activation and repression to take control of the cellular PCNA gene regulation. The cyclic AMP-response element in the PCNA core promoter, besides being crucial for basal transcription, synergizes with p53 to activate transcription. The cyclic AMP response element-binding protein (CREB)-binding protein (CBP) is an essential component of both the transcriptional activation and repression by E1A. Our data demonstrate for the first time that E1A can modulate CBP function to activate PCNA transcription, while at the same time repressing p53-mediated activation by disrupting CBP interaction with p53, thereby uncoupling PCNA transcription from the regulatory effects of p53.
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Affiliation(s)
- S M Karuppayil
- Cancer Therapy and Research Center, The University of Texas Health Science Center, San Antonio, Texas 78229, USA
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Thomas A, White E. Suppression of the p300-dependent mdm2 negative-feedback loop induces the p53 apoptotic function. Genes Dev 1998; 12:1975-85. [PMID: 9649502 PMCID: PMC316960 DOI: 10.1101/gad.12.13.1975] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The p53 tumor suppressor gene product interacts with the p300 transcriptional coactivator that regulates the transactivation of p53-inducible genes. The adenovirus E1A protein has been shown to bind to p300 and inhibit its function. E1A inhibits p53 transactivation and also promotes p53 accumulation by a p300-dependent mechanism. Murine double minute 2 (Mdm2) is a transcriptional target of p53 that binds to p53 and inhibits its transcriptional activity. E1A inhibited mdm2 transactivation without affecting the expression of p21(WAF1) or Bax, which resulted in high levels of p53 accumulation and apoptosis. Ectopic expression of p300 restored Mdm2 levels and inhibited p53-dependent apoptosis, as did ectopic expression of Mdm2. Thus, p300 is required for mdm2 induction by p53 and the subsequent inhibition of p53 stabilization. Inhibition of p300 by E1A results in stabilization of p53 and causes apoptosis. Moreover, E1B 19K or Bcl-2 expression in E1A-transformed cells abrogated p53-dependent apoptosis by restoring mdm2 transactivation by p53. Hence, p300 regulation of mdm2 expression controls apoptotic activity of p53, and 19K or Bcl-2 bypass E1A inhibition of p300 transactivation of Mdm2.
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Affiliation(s)
- A Thomas
- Center for Advanced Biotechnology and Medicine, Cancer Institute of New Jersey, Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854 USA
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Li Z, Yu A, Weiner AM. Adenovirus type 12-induced fragility of the human RNU2 locus requires p53 function. J Virol 1998; 72:4183-91. [PMID: 9557707 PMCID: PMC109647 DOI: 10.1128/jvi.72.5.4183-4191.1998] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Adenovirus type 12 (Ad12) infection of human cells induces four chromosomal fragile sites corresponding to the U1 small nuclear RNA (snRNA) genes (the RNU1 locus), the U2 snRNA genes (RNU2), the U1 snRNA pseudogenes (PSU1), and the 5S rRNA genes (RN5S). Ad12-induced fragility of the RNU2 locus requires U2 snRNA transcriptional regulatory elements and viral early functions but not viral replication or integration, or chromosomal sequences flanking the RNU2 locus. We now show that Ad12 cannot induce the RNU1, RNU2, or PSU1 fragile sites in Saos-2 cells lacking the p53 and retinoblastoma (Rb) proteins but that viral induction of fragility is rescued in these cells when the expression of wild-type p53 or selected hot-spot mutants (i.e., V143A, R175H, R248W, and R273H) is restored by transient expression or stable retroviral transduction. We also observed weak constitutive fragility of the RNU1 and RNU2 loci in cells belonging to xeroderma pigmentosum complementation groups B and D (XPB and XPD) which are partially defective in the ERCC2 (XPD) and ERCC3 (XPB) helicase activities shared between the repairosome and the RNA polymerase H basal transcription factor TFIIH. We propose a model for Ad12-induced chromosome fragility in which interaction of p53 with the Ad12 E1B 55-kDa transforming protein (and possibly E4orf6) induces a p53 gain of function which ultimately perturbs the RNA polymerase II basal transcription apparatus. The p53 gain of function could interfere with chromatin condensation either by blocking mitotic shutdown of U1 and U2 snRNA transcription or by phenocopying global or local DNA damage. Specific fragilization of the RNU1, RNU2, and PSU1 loci could reflect the unusually high local concentration of strong transcription units or the specialized nature of the U1 and U2 snRNA transcription apparatus.
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Affiliation(s)
- Z Li
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA
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