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Subbotina ME, Grunina TM, Sergienko OV, Elkina NV, Elkin DS, Novikova MV, Kopnin PB, Vinokurova SV. Recombinant Antigens E6 and E7 of Human Papilloma Virus Type 16: Preparation, Purification, and Assessment of the Immunogenicity and Antitumor Effects In Vivo. APPL BIOCHEM MICRO+ 2021. [DOI: 10.1134/s0003683821030121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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2
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Choi SB, Kang YS, Bang SK, Bang IS. Expression and characterization of transforming protein E7 from cervical cancer-associated human papillomavirus type 31. BIOTECHNOL BIOPROC E 2014. [DOI: 10.1007/s12257-013-0467-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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3
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Mazzuchelli-de-Souza J, Carvalho RF, Ruiz RM, Melo TC, Araldi RP, Carvalho E, Thompson CE, Sircili MP, Beçak W, Stocco RC. Expression and in Silico analysis of the recombinant bovine papillomavirus E6 protein as a model for viral oncoproteins studies. BIOMED RESEARCH INTERNATIONAL 2013; 2013:421398. [PMID: 23878806 PMCID: PMC3708402 DOI: 10.1155/2013/421398] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 05/16/2013] [Indexed: 12/27/2022]
Abstract
Bovine papillomaviruses (BPVs) are recognized as the causal agents of economical relevant diseases in cattle, associated with the development of tumors in skin and mucosa. The oncogenesis process is mainly associated with different viral oncoprotein expressions, which are involved in cell transformation. The expression and characterization of recombinant viral oncoproteins represent an attractive strategy to obtain biotechnological products as antibodies and potential vaccines, Thus, the aim of this work was to clone and express the BPV-1 and BPV-2 E6 recombinant proteins and perform in silico analysis in order to develop a strategy for the systematic study of other papillomaviruses oncoproteins. The results demonstrated that BPV-1 and BPV-2 E6 recombinant proteins were expressed and purified from bacterial system as well as its in silico analysis was performed in order to explore and predict biological characteristics of these proteins.
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Affiliation(s)
- J. Mazzuchelli-de-Souza
- Laboratório de Genética, Instituto Butantan, Secretaria de Estado da Saúde, Avenida Vital Brasil, 1500 Butantã, 05503-900 São Paulo, SP, Brazil
- Programa de Pós-graduação Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, Edifício ICB-III-Cidade Universitária, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 2415 Butantã, 05508-900 São Paulo, SP, Brazil
| | - R. F. Carvalho
- Laboratório de Genética, Instituto Butantan, Secretaria de Estado da Saúde, Avenida Vital Brasil, 1500 Butantã, 05503-900 São Paulo, SP, Brazil
- Programa de Pós-graduação Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, Edifício ICB-III-Cidade Universitária, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 2415 Butantã, 05508-900 São Paulo, SP, Brazil
| | - R. M. Ruiz
- Laboratório de Genética, Instituto Butantan, Secretaria de Estado da Saúde, Avenida Vital Brasil, 1500 Butantã, 05503-900 São Paulo, SP, Brazil
- Programa de Pós-graduação Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, Edifício ICB-III-Cidade Universitária, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 2415 Butantã, 05508-900 São Paulo, SP, Brazil
| | - T. C. Melo
- Laboratório de Genética, Instituto Butantan, Secretaria de Estado da Saúde, Avenida Vital Brasil, 1500 Butantã, 05503-900 São Paulo, SP, Brazil
- Programa de Pós-graduação em Biologia Estrutural e Funcional, Universidade Federal de São Paulo, Rua Botucatu 740, Vila Clementina, 04023-900 São Paulo, SP, Brazil
| | - R. P. Araldi
- Laboratório de Genética, Instituto Butantan, Secretaria de Estado da Saúde, Avenida Vital Brasil, 1500 Butantã, 05503-900 São Paulo, SP, Brazil
- Programa de Pós-graduação Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, Edifício ICB-III-Cidade Universitária, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 2415 Butantã, 05508-900 São Paulo, SP, Brazil
| | - E. Carvalho
- Laboratório de Biotecnologia Molecular, Instituto Butantan, Secretaria de Estado da Saúde, Avenida Vital Brasil 1500, Butantã, 05503-900 São Paulo, SP, Brazil
| | - C. E. Thompson
- Laboratório Nacional de Computação Científica, Avenida Getúlio Vargas 333, Quitandinha, 25651-075 Petrópolis, RJ, Brazil
| | - M. P. Sircili
- Laboratório de Genética, Instituto Butantan, Secretaria de Estado da Saúde, Avenida Vital Brasil, 1500 Butantã, 05503-900 São Paulo, SP, Brazil
- Programa de Pós-graduação Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, Edifício ICB-III-Cidade Universitária, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 2415 Butantã, 05508-900 São Paulo, SP, Brazil
| | - W. Beçak
- Laboratório de Genética, Instituto Butantan, Secretaria de Estado da Saúde, Avenida Vital Brasil, 1500 Butantã, 05503-900 São Paulo, SP, Brazil
- Departamento de Biologia, Universidade Federal da Integração Latino-Americana (UNILA), Avenida Tancredo Neves 6731 bloco 4, 85867-970 Foz do Iguaçú, PR, Brazil
| | - R. C. Stocco
- Laboratório de Genética, Instituto Butantan, Secretaria de Estado da Saúde, Avenida Vital Brasil, 1500 Butantã, 05503-900 São Paulo, SP, Brazil
- Programa de Pós-graduação Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, Edifício ICB-III-Cidade Universitária, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 2415 Butantã, 05508-900 São Paulo, SP, Brazil
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Tzenov YR, Andrews PG, Voisey K, Popadiuk P, Xiong J, Popadiuk C, Kao KR. Human papilloma virus (HPV) E7-mediated attenuation of retinoblastoma (Rb) induces hPygopus2 expression via Elf-1 in cervical cancer. Mol Cancer Res 2013; 11:19-30. [PMID: 23284001 DOI: 10.1158/1541-7786.mcr-12-0510] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The human papillomavirus (HPV) is the etiologic agent of cervical cancer. In this study, we provide evidence for the human Pygopus (hPygo)2 gene as a cellular biomarker for HPV-related disease. In a tumor microarray of cervical cancer progression, hPygo2 levels were greater in high-grade lesions and squamous cell carcinomas than in normal epithelia. Similarly, hPygo2 mRNA and protein levels were greater in HPV-positive cervical cancer cells relative to uninfected primary cells. RNA interference (RNAi)-mediated depletion of HPV-E7 increased whereas E74-like factor (Elf)-1 RNAi decreased association of Retinoblastoma (Rb) tumor suppressor with the hPygo2 promoter in cervical cancer cell lines. Transfection of dominant-active Rb inhibited Elf-1-dependent activation of hPygo2, whereas Elf-1 itself increased hPygo2 expression. Chromatin immunoprecipitation assays showed that Rb repressed hPygo2 by inhibiting Elf-1 at the Ets-binding site in the hPygo2 promoter. These results suggested that abrogation of Rb by E7 resulted in derepression of Elf-1, which in turn stimulated expression of hPygo2. Thus, initiation of hPygo2 expression by Elf-1 was required for proliferation of cervical cancer cells and its expression therefore may act as a surrogate marker for dysplasia.
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Affiliation(s)
- Youlian R Tzenov
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Philip Drive, St. John's, NL, Canada, A1B 3V6
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Ramakrishnan C, Subramanian V, Balamurugan K, Velmurugan D. Molecular dynamics simulations of retinoblastoma protein. J Biomol Struct Dyn 2012; 31:1277-92. [PMID: 23157310 DOI: 10.1080/07391102.2012.732345] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tumor suppressor proteins play a crucial role in cell cycle regulation. Retinoblastoma protein (pRB) is one among them which regulates G1-S transition by binding with transcription factors. The activity of pRB is deregulated by cyclin dependent kinases-mediated hyper-phosphorylation and also due to cancer-derived mutations. In addition, it is also deactivated by binding of viral onco-proteins such as large T antigen, E1A, and E7. These viral proteins initially recognize pRB through their conserved LxCxE motif and facilitate dissociation of preexisting pRB-E2F complex. Based on these features, molecular dynamics (MD) simulation is performed for four different states of pRB for which the crystal structure is available. The unliganded/apo form and complex forms with E2F and E7 peptides reveal the molecular mechanism behind the activation and inactivation of pRB. In addition, the ternary complex of pRB with both E7 and E2F (for which no crystal structure is available) is modeled and simulated to understand the influence of binding of one ligand on the other. The variations in the three major factors such as conformational changes, inter- and intra-molecular interactions, and binding free energies between the apo and complex forms confirm the possibility for designing a small molecule inhibitor to inhibit pRB-E7 interactions without altering the prebound E2F. The present study deals with the molecular modeling and MD simulations of pRB in free and ligand-bound forms and confirms that pRB could be a valid target for the anticancer drug design when the cancer is induced by the viral onco-proteins and forms a clear base for designing E7 antagonists.
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Affiliation(s)
- C Ramakrishnan
- a Centre of Advanced Study in Crystallography and Biophysics, University of Madras , Maraimalai (Guindy) Campus, Chennai , 600025 , India
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Efficient expression of Human papillomavirus 16 E7 oncoprotein fused to C-terminus of Tobacco mosaic virus (TMV) coat protein using molecular chaperones in Escherichia coli. Protein Expr Purif 2012; 85:152-7. [PMID: 22850536 DOI: 10.1016/j.pep.2012.07.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 07/10/2012] [Accepted: 07/17/2012] [Indexed: 11/21/2022]
Abstract
The Human papillomavirus 16 (HPV16) E7 oncoprotein is a promising candidate for development of anti-cancer therapeutic vaccine. We have prepared the expression construct carrying mutagenized E7 oncoprotein fused to the C-terminus of Tobacco mosaic virus (TMV) coat protein via 15 amino acids β-sheet linker. The fusion protein was expressed in Escherichia coli MC 1061 cells. We have obtained high level expression, but most of the protein remained in insoluble inclusion bodies. To increase the ratio of soluble protein various molecular chaperones (TF, DnaK-DnaJ-GrpE, GroEL-GroES) were used. The immunological reactivity of expressed recombinant protein was evaluated with anti-E7 and anti-TMV antibodies. The distribution of expressed product during ultracentrifugation on sucrose gradient was studied.
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Plchova H, Moravec T, Hoffmeisterova H, Folwarczna J, Cerovska N. Expression of Human papillomavirus 16 E7ggg oncoprotein on N- and C-terminus of Potato virus X coat protein in bacterial and plant cells. Protein Expr Purif 2011; 77:146-52. [PMID: 21266198 DOI: 10.1016/j.pep.2011.01.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 01/18/2011] [Accepted: 01/18/2011] [Indexed: 11/21/2022]
Abstract
The E7 oncoprotein from Human papillomavirus type 16 (HPV16) is an attractive candidate for anti-cancer therapeutical vaccine development. In this study, we engineered different fusions of mutagenized coding sequence of E7 oncoprotein (E7ggg) with coat protein of Potato virus X (PVX CP) both on 5'- and 3'-terminus of PVX CP and evaluated the influence of the length of linker (no linker, 4, 15aa) connecting PVX CP and E7ggg on their production. At first the expression in Escherichia coli was conducted to assess the characteristics of the recombinant protein prior to be further produced in plants, that is, resultant proteins were used for screening of their immunological reactivity with antibodies against PVX CP and E7. Fusion proteins successfully expressed in bacteria and plants were partially purified and their reactivity and ability to form virus-like particles were evaluated with anti-E7 antibodies.
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Affiliation(s)
- Helena Plchova
- Academy of Sciences of the Czech Republic, 160 00 Prague 6, Czech Republic
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Petrone L, Ammendolia MG, Cesolini A, Caimi S, Superti F, Giorgi C, Di Bonito P. Recombinant HPV16 E7 assembled into particles induces an immune response and specific tumour protection administered without adjuvant in an animal model. J Transl Med 2011; 9:69. [PMID: 21592382 PMCID: PMC3120688 DOI: 10.1186/1479-5876-9-69] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 05/18/2011] [Indexed: 01/20/2023] Open
Abstract
Background The HPV16 E7 protein is both a tumour-specific and a tumour-rejection antigen, the ideal target for developing therapeutic vaccines for the treatment of HPV16-associated cancer and its precursor lesions. E7, which plays a key role in virus-associated carcinogenesis, contains 98 amino acids and has two finger-type structures which bind a Zn++ ion. The ability of an Escherichia coli-produced E7-preparation, assembled into particles, to induce protective immunity against a HPV16-related tumour in the TC-1-C57BL/6 mouse tumour model, was evaluated. Methods E7 was expressed in E. coli, purified via a one-step denaturing protocol and prepared as a soluble suspension state after dialysis in native buffer. The presence in the E7 preparation of particulate forms was analysed by non-reducing SDS-PAGE and negative staining electron microscopy (EM). The Zn++ ion content was analysed by mass-spectrometry. Ten μg of protein per mouse was administered to groups of animals, once, twice or three times without adjuvant. The E7-specific humoral response was monitored in mice sera using an E7-based ELISA while the cell-mediated immune response was analysed in mice splenocytes with lymphoproliferation and IFN-γ ELISPOT assays. The E7 immunized mice were challenged with TC-1 tumour cells and the tumour growth monitored for two months. Results In western blot analysis E7 appears in multimers and high molecular mass oligomers. The EM micrographs show the protein dispersed as aggregates of different shape and size. The protein appears clustered in micro-, nano-aggregates, and structured particles. Mice immunised with this protein preparation show a significant E7-specific humoral and cell-mediated immune response of mixed Th1/Th2 type. The mice are fully protected from the tumour growth after vaccination with three E7-doses of 10 μg without any added adjuvant. Conclusions This report shows that a particulate form of HPV16 E7 is able to induce, without adjuvant, an E7-specific tumour protection in C57BL/6 mice. The protective immunity is sustained by both humoral and cell-mediated immune responses. The E. coli-derived HPV16 E7 assembled in vitro into micro- and nanoparticles represents not only a good substrate for antigen-presenting cell uptake and processing, but also a cost-effective means for the production of a new generation of HPV subunit vaccines.
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Affiliation(s)
- Linda Petrone
- Department of Infectious Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, Rome, Italy
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Granadillo M, Vallespi MG, Batte A, Mendoza O, Soria Y, Lugo VM, Torrens I. A novel fusion protein-based vaccine comprising a cell penetrating and immunostimulatory peptide linked to human papillomavirus (HPV) type 16 E7 antigen generates potent immunologic and anti-tumor responses in mice. Vaccine 2010; 29:920-30. [PMID: 21145912 DOI: 10.1016/j.vaccine.2010.11.083] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 11/03/2010] [Accepted: 11/10/2010] [Indexed: 11/17/2022]
Abstract
The ultimate success of cancer vaccination is dependent upon the generation of tumor-specific CTLs. In this study, we designed and evaluated a novel fusion protein comprising a cell penetrating and immunostimulatory peptide corresponding to residues 32-51 of the Limulus polyphemus protein (LALF(32-51)) linked to human papillomavirus (HPV) 16 E7 antigen (LALF(32-51)-E7). We demonstrated that LALF(32-51) penetrates the cell membrane and delivers E7 into cells. In a preclinical model of HPV16-induced cervical carcinoma we showed that vaccination with adjuvant-free LALF(32-51)-E7 fusion protein significantly improves the presentation of E7-derived peptides to T-cells in vitro and induces suppression of tumor growth.
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Affiliation(s)
- Milaid Granadillo
- Department of Cancer, Center for Genetic Engineering and Biotechnology, P.O. Box 6162, Cubanacan, Playa, Havana 10600, Cuba.
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10
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A C-terminal hydrophobic, solvent-protected core and a flexible N-terminus are potentially required for human papillomavirus 18 E7 protein functionality. Biochimie 2010; 92:901-8. [DOI: 10.1016/j.biochi.2010.02.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Accepted: 02/19/2010] [Indexed: 11/21/2022]
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Morgenfeld M, Segretin ME, Wirth S, Lentz E, Zelada A, Mentaberry A, Gissmann L, Bravo-Almonacid F. Potato virus X coat protein fusion to human papillomavirus 16 E7 oncoprotein enhance antigen stability and accumulation in tobacco chloroplast. Mol Biotechnol 2009; 43:243-9. [PMID: 19579017 DOI: 10.1007/s12033-009-9195-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Accepted: 06/10/2009] [Indexed: 10/20/2022]
Abstract
Cervical cancer linked to infection with human papillomavirus (HPV) is the third cause of cancer-related death in women. As the virus cannot be propagated in culture, vaccines have been based on recombinant antigens with inherited high-cost production. In a search of alternative cheap production system, E7 HPV type 16 protein, an attractive candidate for anticancer vaccine development, was engineered to be expressed in tobacco chloroplast. In addition, E7 coding sequence was fused to potato virus X coat protein (CP) to compare expression level. Results show that E7CP transcript accumulation reached lower levels than non-fused E7. However, antigen expression levels were higher for fusion protein indicating that CP stabilizes E7 peptide in the chloroplast stroma. These results support viability of transplastomic plants for antigen production and the relevance of improving recombinant peptide stability for certain transgenes to enhance protein accumulation in this organelle.
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Affiliation(s)
- Mauro Morgenfeld
- Instituto de Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Vuelta de Obligado 2490, C.C. 1428, Ciudad Autónoma de Buenos Aires, Argentina
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12
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Yan W, Huang L. The effects of salt on the physicochemical properties and immunogenicity of protein based vaccine formulated in cationic liposome. Int J Pharm 2008; 368:56-62. [PMID: 18992312 DOI: 10.1016/j.ijpharm.2008.09.053] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 09/29/2008] [Accepted: 09/30/2008] [Indexed: 11/25/2022]
Abstract
Recently, we have developed a simple and potent therapeutic cancer vaccine consisting of a cationic lipid and a peptide antigen. In this report, we expanded the utility of this formulation to protein based vaccines. First, we formulated the human papillomavirus (HPV) 16 E7 protein (E7) in different doses of DOTAP liposome. The results showed that these formulations failed to regress an established tumor. However, when sodium chloride (30 mM) was added to the DOTAP (100 nmol)/E7 (20 microg) formulation, anti-tumor activity was generated in the immunized mice. Correlatively, 30 mM NaCl in the DOTAP/E7 protein formulation increased the particle size from approximately 350 to 550 nm, decreased the protein loading capacity (from 95 to 90%), and finally increased the zeta potential (from 29 to 38 mV). Next, a model protein antigen ovalbumin (OVA) was formulated in different doses of DOTAP liposomes. Similarly, the results showed that 20 microg OVA formulated in 200 nmol DOTAP with 30 mM NaCl had the best OVA-specific antibody response, including both IgG(1) and IgG(2a), suggesting both Th1 and Th2 immune responses were generated by this formulation. In conclusion, we have expanded the application of cationic DOTAP liposome formulation to protein based vaccines and also identified that small amounts of salt could change the physicochemical properties of the vaccine formulation and enhance the activity of the DOTAP/protein based vaccine. The enhancement of immune responses by salt is possibly due to its interference of the electrostatic interaction between the cationic lipid and the protein antigen to facilitate the antigen release from the carrier and at the same time activate the antigen presenting cells.
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Affiliation(s)
- Weili Yan
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, 2316 Kerr Hall, CB# 7360, Chapel Hill, NC 27599-7360, USA
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Uversky VN, Roman A, Oldfield CJ, Dunker AK. Protein intrinsic disorder and human papillomaviruses: increased amount of disorder in E6 and E7 oncoproteins from high risk HPVs. J Proteome Res 2007; 5:1829-42. [PMID: 16889404 DOI: 10.1021/pr0602388] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is recognized now that many functional proteins or their long segments are devoid of stable secondary and/or tertiary structure and exist instead as very dynamic ensembles of conformations. They are known by different names including natively unfolded, intrinsically disordered, intrinsically unstructured, rheomorphic, pliable, and different combinations thereof. Many important functions and activities have been associated with these intrinsically disordered proteins (IDPs), including molecular recognition, signaling, and regulation. It is also believed that disorder of these proteins allows function to be readily modified through phosphorylation, acetylation, ubiquitination, hydroxylation, and proteolysis. Bioinformatics analysis revealed that IDPs comprise a large fraction of different proteomes. Furthermore, it is established that the intrinsic disorder is relatively abundant among cancer-related and other disease-related proteins and IDPs play a number of key roles in oncogenesis. There are more than 100 different types of human papillomaviruses (HPVs), which are the causative agents of benign papillomas/warts, and cofactors in the development of carcinomas of the genital tract, head and neck, and epidermis. With respect to their association with cancer, HPVs are grouped into two classes, known as low (e.g., HPV-6 and HPV-11) and high-risk (e.g., HPV-16 and HPV-18) types. The entire proteome of HPV includes six nonstructural proteins [E1, E2, E4, E5, E6, and E7 (the latter two are known to function as oncoproteins in the high-risk HPVs)] and two structural proteins (L1 and L2). To understand whether intrinsic disorder plays a role in the oncogenic potential of different HPV types, we have performed a detailed bioinformatics analysis of proteomes of high-risk and low-risk HPVs with the major focus on E6 and E7 oncoproteins. The results of this analysis are consistent with the conclusion that high-risk HPVs are characterized by the increased amount of intrinsic disorder in transforming proteins E6 and E7.
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Affiliation(s)
- Vladimir N Uversky
- Department of Biochemistry and Molecular Biology, Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, 46202, USA.
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Mirecka EA, Rudolph R, Hey T. Expression and purification of His-tagged HPV16 E7 protein active in pRb binding. Protein Expr Purif 2006; 48:281-91. [PMID: 16814565 DOI: 10.1016/j.pep.2006.04.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 04/16/2006] [Accepted: 04/17/2006] [Indexed: 12/23/2022]
Abstract
Human papillomavirus type 16 (HPV16) protein E7 is the major oncogenic factor associated with the development of human cervical cancer. The transforming activity of the E7 protein is linked to its interaction with host regulatory proteins such as the retinoblastoma tumor suppressor protein. The recombinant production of E7 protein is a prerequisite for its structural and functional characterization as well as for the development of various preventive and therapeutic strategies. We present an approach to enhance the soluble expression of His-tagged E7 protein by optimization of the E7 gene and the expression conditions in the host Escherichia coli. We also report a detailed protocol for the purification of E7 protein by standard chromatographic methods. The binding of E7 protein to the recombinant non-phosphorylated form of retinoblastoma protein was examined by ELISA and surface plasmon resonance analysis. These studies confirm that the recombinant His-tagged E7 protein retains its conformational properties and biological activity.
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Affiliation(s)
- Ewa A Mirecka
- Institut für Biotechnologie, Martin-Luther-Universität Halle/Wittenberg, Halle (Saale), Germany
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15
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Abstract
Human papillomavirus (HPV) is the most common sexually transmitted infection, with > 50% of sexually active women being affected. The virus causes a wide variety of benign and pre-malignant epithelial tumours and although most infections are transient, it is estimated that 1% of the sexually active population in the US have clinically apparent genital warts. A subset of genital HPVs, termed high-risk HPVs, is highly associated with the development of genital cancers including cervical carcinoma. Therapies for these HPV related cancers are however outside of the scope of this review. The absence of a simple monolayer cell culture system for analysis and propagation of the virus has substantially retarded progress in the development of diagnostic and therapeutic strategies for HPV infection. In spite of these difficulties, great progress has been made in the elucidation of the molecular controls of virus gene expression, replication and pathogenesis, and there has been some progress in the development of prophylactic and therapeutic vaccines and of other therapies.
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Affiliation(s)
- F X Wilson
- Roche Discovery Welwyn, Broadwater Road, Welwyn Garden City, Herts, AL7 3AY, UK
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16
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Alonso LG, García-Alai MM, Smal C, Centeno JM, Iacono R, Castaño E, Gualfetti P, de Prat-Gay G. The HPV16 E7 Viral Oncoprotein Self-Assembles into Defined Spherical Oligomers†. Biochemistry 2004; 43:3310-7. [PMID: 15035602 DOI: 10.1021/bi036037o] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Despite the fact that E7 is a major transforming oncoprotein in papillomavirus, its structure and precise molecular mechanism of action remain puzzling to date. E7 proteins share sequence homology and proteasome targeting properties of tumor suppressors with adenovirus E1A and SV40 T antigen, two other paradigmatic oncoproteins from DNA tumor viruses. High-risk HPV16 E7, a nonglobular dimer with some properties of intrinsically disordered proteins, is capable of undergoing pH-dependent conformational transitions that expose hydrophobic surfaces to the solvent. We found that treatment with a chelating agent produced a protein that can readily assemble into homogeneous spherical particles with an average molecular mass of 790 kDa and a diameter of 50 nm, as determined from dynamic light scattering and electron microscopy. The protein undergoes a substantial conformational transition from coil to beta-sheet structure, with concomitant consolidation of tertiary structure as judged by circular dichroism and fluorescence. The assembly process is very slow, in agreement with a substantial energy barrier caused by structural rearrangements. The resulting particles are highly stable, cooperatively folded, and capable of binding both Congo Red and thioflavin T, reporters of repetitive beta-sheet structures similar to those found in amyloids, although no fibrillar or insoluble material was observed under our experimental conditions.
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Affiliation(s)
- Leonardo G Alonso
- Instituto Leloir, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Patricias Argentinas 435, (1405) Buenos Aires, Argentina
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Alonso LG, García-Alai MM, Nadra AD, Lapeña AN, Almeida FL, Gualfetti P, Prat-Gay GD. High-risk (HPV16) human papillomavirus E7 oncoprotein is highly stable and extended, with conformational transitions that could explain its multiple cellular binding partners. Biochemistry 2002; 41:10510-8. [PMID: 12173938 DOI: 10.1021/bi025579n] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High-risk papillomaviruses are known to exert their transforming activity mainly through E7, one of their two oncoproteins. Despite its relevance, no structural information has been obtained that could explain the apparent broad binding specificity of E7. Recombinant E7 from HPV-16 purified to near homogeneity showed two species in gel filtration chromatography, one of these corresponding to a dimer with a molecular weight of 22 kDa, determined by multiangle light scattering. The E7 dimer was isolated for characterization and was shown to undergo a substantial conformational transition when changing from pH 7.0 to 5.0, with an increase in helical structure and increased solvent accessibility to hydrophobic surfaces. The protein was resistant to thermal denaturation even in the presence of SDS, and we show that persistent residual structure in the monomer is responsible for its reported anomalous electrophoretic behavior. The dimer also displays a nonglobular hydrodynamic volume based on gel filtration experiments and becomes more globular in the presence of 0.3 M guanidinium chloride, with hydrophobic surfaces becoming accessible to the solvent, as indicated by the large increase in ANS binding. At low protein concentration, dissociation of the globular E7 dimer was observed, preceding the cooperative unfolding of the structured and extended monomer. Although E7 bears properties that resemble natively unfolded polypeptides, its far-UV circular dichroism spectrum, cooperative unfolding, and exposure of ANS binding sites support a folded and extended, as opposed to disordered and fluctuating, conformation. The large increase in solvent accessibility to hydrophobic surfaces upon small pH decrease within physiological range and in mild denaturant concentrations suggests conformational properties that could have evolved to enable protein-protein recognition of the large number of cellular binding partners reported.
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Affiliation(s)
- Leonardo G Alonso
- Instituto Leloir, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Patricias Argentinas 435, (1405) Buenos Aires, Argentina
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18
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Chun YM, Moon SK, Lee HY, Webster P, Brackmann DE, Rhim JS, Lim DJ. Immortalization of normal adult human middle ear epithelial cells using a retrovirus containing the E6/E7 genes of human papillomavirus type 16. Ann Otol Rhinol Laryngol 2002; 111:507-17. [PMID: 12090706 DOI: 10.1177/000348940211100606] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A human middle ear epithelial cell line (HMEEC-1) was established using human papillomavirus E6/E7 genes. HMEEC-1 has remained morphologically and phenotypically stable, even after 50 passages. The cells are anchorage-dependent and nontumorigenic when injected into nude mice. This cell line thus provides a new tool for the study of normal cell biology and the pathological processes associated with the epithelial cells of the middle ear in otitis media. HMEEC-1 will also be useful in the search for new drugs and biological agents for the treatment of otitis media.
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Affiliation(s)
- Young-Myoung Chun
- Gonda Department of Cell and Molecular Biology, Los Angeles, California, USA
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19
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Dunker AK, Brown CJ, Lawson JD, Iakoucheva LM, Obradović Z. Intrinsic disorder and protein function. Biochemistry 2002; 41:6573-82. [PMID: 12022860 DOI: 10.1021/bi012159+] [Citation(s) in RCA: 1322] [Impact Index Per Article: 60.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A Keith Dunker
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA.
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20
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Lee YL, Lee KF, Xu JS, Wang YL, Tsao SW, Yeung WS. Establishment and characterization of an immortalized human oviductal cell line. Mol Reprod Dev 2001; 59:400-9. [PMID: 11468776 DOI: 10.1002/mrd.1046] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Human oviductal cells stimulate embryo development in vitro partly by the production of embryotrophic glycoproteins. The identity of these glycoproteins is not yet known mainly because oviductal samples are limited and that the cultured parental oviductal cells cannot produce sufficient amount of embryotrophic factors for characterization. In this study, human oviductal epithelial cells (OE) were immortalized by HPV 16 E6/E7 open reading frame (ORF) by retroviral expression. The characteristics of this immortalized cell line (OE-E6/E7) were compared to the parental OE. HPV 16 E6/E7 DNA was found only in OE-E6/E7 but not in OE. Human oviduct-specific glycoprotein, estrogen receptors, and cytokeratin were found in both cell types. Both OE and OE-E6/E7 possessed telomerase activities but the former had much lower activity. OE-E6/E7 also produced glycoproteins with chromatographic behavior similar to the embryotrophic glycoproteins derived from OE. These results showed that OE-E6/E7 retained a number of characteristics of OE. The development of preimplantation mouse embryo was significantly better after coculture with OE-E6/E7 when compared to medium alone culture in term of blastulation rates (52% vs. 32%) and blastocyst diameter (113.0 +/- 2.07 microm vs. 83.9 +/- 5.23 microm). This immortalized cell line can be used as a continuous and stable in vitro system for the study of the oviductal embryotrophic activity. Mol. Reprod. Dev. 59: 400-409, 2001.
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Affiliation(s)
- Y L Lee
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Hong Kong, China
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21
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Youk EG, Ku JL, Park JG. Detection and typing of human papillomavirus in anal epidermoid carcinomas: sequence variation in the E7 gene of human papillomavirus Type 16. Dis Colon Rectum 2001; 44:236-42. [PMID: 11227941 DOI: 10.1007/bf02234299] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
INTRODUCTION Human papillomavirus, particularly Type 16, plays a central role in the development of anogenital squamous-cell carcinomas. A common sequence variation of human papillomavirus Type 16 in cervical cancer cell lines and in cervical cancer tissues from Korean patients was recently reported. The present study was performed to determine the integration type of human papillomavirus DNA in anal epidermoid carcinoma and to identify the common sequence variations in the human papillomavirus Type 16 E7 gene that had been previously reported. METHODS Twenty-one formalin-fixed, paraffin-embedded specimens collected from 29 patients with anal epidermoid carcinomas treated at the Seoul National University Hospital over a ten-year period (1989-1998) were investigated. Genomic DNA from the 21 specimens was extracted and analyzed using the polymerase chain reaction with a general primer and a type-specific primer for human papillomavirus Types 16 and 18. Direct sequencing was performed. As a control, 13 normal anal epithelia available from these patients were microdissected. As another control, 21 hemorrhoidal squamous epithelia obtained from a demographically adjusted group were also analyzed. RESULTS Human papillomavirus Type 16 DNA was present in all 21 anal epidermoid carcinomas. All controls were negative for human papillomavirus DNA. Sequence analysis revealed that 57 percent (12/21) specimens showed two types of sequence variation in the E7 gene. One variant with a single nucleotide change at position 647 (amino acid 29, AAT-->AGT, asparagine to serine) was found in 38 percent (8/21) of the samples. This variant has been detected in cervical cancers from Korean patients: 19 (39 percent) of 49 cervical cancer tissues and 6 (50 percent) of 12 cervical cancer cell lines. Another single nucleotide change at position 645 (amino acid 28, TTA-->TTC, leucine to phenylalanine) was found in 19 percent (4/21) of the samples. These two variants exhibit a change of amino acid affecting the critical sites for Rb binding. CONCLUSION Human papillomavirus Type 16 was found to be present in all 21 anal epidermoid carcinomas. Furthermore, in the Korean population, the most common sequence variant found in cervical
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Affiliation(s)
- E G Youk
- Laboratory of Cell Biology, Cancer Research Institute, Seoul National University College of Medicine, Korea
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22
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Clements A, Johnston K, Mazzarelli JM, Ricciardi RP, Marmorstein R. Oligomerization properties of the viral oncoproteins adenovirus E1A and human papillomavirus E7 and their complexes with the retinoblastoma protein. Biochemistry 2000; 39:16033-45. [PMID: 11123931 DOI: 10.1021/bi002111g] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human papillomavirus 16 E7 (HPV16 E7) and adenovirus 5 E1A (Ad5 E1A) are encoded by highly divergent viruses yet are functionally similar in their ability to bind the retinoblastoma (pRB) tumor suppressor protein, causing the aberrant displacement of E2F trancription factors. The amino acid residues of HPV16 E7 that are necessary for stability, for inhibition of pRB function, and for cell transformation are also necessary for E7 oligomerization. However, neither the specific oligomerization state of HPV16 E7 nor of Ad5 E1A as a function of pRB-binding has been characterized. To gain insight into HPV16 E7 and Ad5 E1A oligomerization properties, sedimentation equilibrium experiments were performed with recombinant HPV16 E7 and Ad5 E1A proteins. These studies reveal that, despite the overall functional similarities between these proteins, monomers, dimers, and tetramers of HPV16 E7 were detected while only reversible monomer-dimer association was identified for Ad5 E1A. The apparent K(d(monomer)-(dimer)) of HPV16 E7 is approximately 100-fold lower than that of a comparable region of Ad5 E1A, and it is concluded that under physiological protein concentrations HPV16 E7 exists primarily as a dimer. Sedimentation equilibrium experiments of pRB/Ad5 E1A and of pRB/HPV16 E7 complexes demonstrate that the tight association of pRB with the viral oncoproteins does not disturb their inherent oligomerization properties. Taken together, this study demonstrates significant differences between the Ad5 E1A and HPV16 E7 oligomerization states that are potentially related to their distinct structures and specific mechanisms of pRB-inactivation.
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Affiliation(s)
- A Clements
- The Wistar Institute, Department of Biochemistry and Biophysics, University of Pennsylvania Dental School, and The Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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23
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Abstract
"Natively unfolded" proteins occupy a unique niche within the protein kingdom in that they lack ordered structure under conditions of neutral pH in vitro. Analysis of amino acid sequences, based on the normalized net charge and mean hydrophobicity, has been applied to two sets of proteins: small globular folded proteins and "natively unfolded" ones. The results show that "natively unfolded" proteins are specifically localized within a unique region of charge-hydrophobicity phase space and indicate that a combination of low overall hydrophobicity and large net charge represent a unique structural feature of "natively unfolded" proteins.
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Affiliation(s)
- V N Uversky
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA.
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24
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25
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Choo CK, Ling MT, Chan KW, Tsao SW, Zheng Z, Zhang D, Chan LC, Wong YC. Immortalization of human prostate epithelial cells by HPV 16 E6/E7 open reading frames. Prostate 1999; 40:150-8. [PMID: 10398276 DOI: 10.1002/(sici)1097-0045(19990801)40:3<150::aid-pros2>3.0.co;2-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND The exact pathogenesis for prostate cancer is not known. Progress made in prostate cancer research has been slow, largely due to the lack of suitable in vitro models. Here, we report our work on the immortalization of a human prostate epithelial cell line and show that it can be used as a model to study prostate tumorigenesis. METHODS Replication-defective retrovirus harboring the human papillomavirus (HPV) type 16 E6 and E7 open reading frames was used to infect primary human prostate epithelial cells. Polymerase chain reaction, followed by Southern hybridization for the HPV 16 E6/E7, Western blot for prostatic acid phosphatase, telomeric repeat amplification protocol assay for telomerase activity, two-dimensional gels for cytokeratins, and cytogenetic analysis were undertaken to characterized the infected cells. RESULTS The retrovirus-infected cell line, HPr-1, continued to grow in culture for more than 80 successive passages. Normal primary cells failed to proliferate after passage 6. HPr-1 cells bore close resemblance to normal primary prostate epithelial cells, both morphologically and biochemically. However, they possessed telomerase activity and proliferated indefinitely. Cytogenetic analysis of HPr-1 cells revealed a human male karyotype with clonal abnormalities and the appearance of multiple double minutes. CONCLUSIONS The HPr-1 cells expressed prostatic acid phosphatase and cytokeratins K8 and K18, proving that they were prostate epithelial cells. They were benign in nude mice tumor formation and soft agar colony formation assay. The HPr-1 cell line is an in vitro representation of early prostate neoplastic progression.
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Affiliation(s)
- C K Choo
- Department of Pathology, University of Hong Kong, Hong Kong, China.
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26
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Fernando GJ, Murray B, Zhou J, Frazer IH. Expression, purification and immunological characterization of the transforming protein E7, from cervical cancer-associated human papillomavirus type 16. Clin Exp Immunol 1999; 115:397-403. [PMID: 10193409 PMCID: PMC1905249 DOI: 10.1046/j.1365-2249.1999.00813.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
E7 is the major oncogenic protein produced in cervical cancer-associated human papillomavirus type 16 (HPV16). This protein was expressed in Escherichia coli as a glutathione-S-transferase (GST) fusion protein. E7-enriched inclusion bodies were collected from bacterial lysates, were solubilized in 10 M urea, and the protein was purified using anion exchange column chromatography. After removal of endotoxin with serial Triton X-114 extractions, material of high purity (about 90%) was obtained, which is suitable for use in a human clinical trial. This material was immunogenic, and when used as a vaccine, protected mice against challenge with an HPV16 E7 DNA transfected tumour cell line. Based on this observation, the E7GST fusion protein is currently being used in a human clinical trial of a vaccine against HPV16-induced cervical cancer. This fusion protein could be cleaved with thrombin to remove the GST fusion part and further purified by preparative SDS gel electrophoresis to obtain free E7 with > 98% purity.
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Affiliation(s)
- G J Fernando
- University of Queensland, Department of Medicine, Princess Alexandra Hospital, Brisbane, Australia
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27
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Phelps WC, Barnes JA, Lobe DC. Molecular targets for human papillomaviruses: prospects for antiviral therapy. Antivir Chem Chemother 1998; 9:359-77. [PMID: 9875390 DOI: 10.1177/095632029800900501] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A substantial medical need exists for the development of antiviral medicines for the treatment of diseases associated with infection by human papillomaviruses (HPVs). HPVs are associated with various benign and malignant lesions including benign genital condyloma, common skin warts, laryngeal papillomas and anogenital cancer. Since treatment options are limited and typically not very satisfactory, the development of safe and effective antiviral drugs for HPV could have substantial clinical impact. In the last few years, exciting advances have been made in our understanding of papillomavirus replication and the effects that the virus has on growth of the host cell. Although still somewhat rudimentary, techniques have been developed for limited virion production in vitro offering the promise of more rapid advances in the dissection and understanding of the virus life cycle. Of the 8-10 HPV gene products that are made during infection, only one encodes enzymatic activities, the E1 helicase. Successful antiviral therapies have traditionally targeted viral enzymes such as polymerases, kinases and proteases. In contrast, macromolecular interactions which mediate the functions of E6, E7 and E2 are thought to be more difficult targets for small molecule therapy.
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Affiliation(s)
- W C Phelps
- Department of Virology, Glaxo Wellcome Inc, Research Triangle Park, North Carolina 27709-3398, USA.
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28
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Song YS, Kee SH, Kim JW, Park NH, Kang SB, Chang WH, Lee HP. Major sequence variants in E7 gene of human papillomavirus type 16 from cervical cancerous and noncancerous lesions of Korean women. Gynecol Oncol 1997; 66:275-81. [PMID: 9264576 DOI: 10.1006/gyno.1997.4756] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Geographic specificity of nucleotide sequence variations in the coding and noncoding regions of HPV 16 genome has been reported. Little has been known, however, regarding whether these naturally occurring sequence variations of HPV 16 may result in marked differences in biological properties, such as oncogenic potential. This study was performed to identify sequence variants in the HPV 16 E7 gene derived from Korean women with cervical cancerous and noncancerous lesions, and to assess the association between the sequence variant and the cervical cancer. We examined E7 variants of HPV 16 in a total of 157 patients with no cervical disease (NCD, n = 87) or cervical neoplasia (cervical intraepithelial neoplasia 3, n = 21; cervical carcinoma, n = 49), using the nested polymerase chain reaction (PCR) and the PCR-directed sequencing methods with outer consensus and inner type-specific primers. Forty-two (NCD, n = 9; CIN 3, n = 6; cervical carcinoma, n = 27) of 157 cervical samples contained HPV 16 E7 DNA, but only 8 had prototype sequences. Four variants of the HPV 16 E7 gene were identified. The variant with a single nucleotide change at position 647 (A --> G, Asn --> Ser) was found in about 60% of DNA samples with HPV 16. The second most common variant, found in 16.7% of cases, had three silent mutations at positions 732 (T --> C), 789 (T --> C), and 795 (T --> G). Two other variants were detected, one in a patient with cervical cancer and the other in a patient with no cervical disease. One had a single nucleotide change at position 666 (G --> A) and the other had one silent mutation at position 796 (T --> C). The most common variant in Korea has a change of nucleotide affecting the predicted amino acid related with high antigenicity and binding to retinoblastoma protein. There was a statistically significant trend for this variant to be more frequently detected in cancerous lesions of the uterine cervix than in noncancerous lesions. These data suggest that naturally occurring sequence variants of HPV 16 E7 gene may have different oncogenic properties.
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Affiliation(s)
- Y S Song
- Department of Obstetrics and Gynecology, Seoul National University Hospital, Korea
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29
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Affiliation(s)
- CG Ullman
- Department of Biochemistry, Royal Free Hospital School of Medicine, Rowland Hill Street, Hampstead NW3 2QG, UK
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