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Pinheiro M, Harari A, Schiffman M, Clifford GM, Chen Z, Yeager M, Cullen M, Boland JF, Raine-Bennett T, Steinberg M, Bass S, Xiao Y, Tenet V, Yu K, Zhu B, Burdett L, Turan S, Lorey T, Castle PE, Wentzensen N, Burk RD, Mirabello L. Phylogenomic Analysis of Human Papillomavirus Type 31 and Cervical Carcinogenesis: A Study of 2093 Viral Genomes. Viruses 2021; 13:1948. [PMID: 34696378 PMCID: PMC8540939 DOI: 10.3390/v13101948] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/09/2021] [Accepted: 09/21/2021] [Indexed: 12/17/2022] Open
Abstract
Human papillomavirus (HPV) type 31 (HPV31) is closely related to the most carcinogenic type, HPV16, but only accounts for 4% of cervical cancer cases worldwide. Viral genetic and epigenetic variations have been associated with carcinogenesis for other high-risk HPV types, but little is known about HPV31. We sequenced 2093 HPV31 viral whole genomes from two large studies, one from the U.S. and one international. In addition, we investigated CpG methylation in a subset of 175 samples. We evaluated the association of HPV31 lineages/sublineages, single nucleotide polymorphisms (SNPs) and viral methylation with cervical carcinogenesis. HPV31 A/B clade was >1.8-fold more associated with cervical intraepithelial neoplasia grade 3 and cancer (CIN3+) compared to the most common C lineage. Lineage/sublineage distribution varied by race/ethnicity and geographic region. A viral genome-wide association analysis identified SNPs within the A/B clade associated with CIN3+, including H23Y (C626T) (odds ratio = 1.60, confidence intervals = 1.17-2.19) located in the pRb CR2 binding-site within the E7 oncogene. Viral CpG methylation was higher in lineage B, compared to the other lineages, and was most elevated in CIN3+. In conclusion, these data support the increased oncogenicity of the A/B lineages and suggest variation of E7 as a contributing risk factor.
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Affiliation(s)
- Maisa Pinheiro
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
| | - Ariana Harari
- Departments of Pediatrics and Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA;
| | - Mark Schiffman
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
| | - Gary M. Clifford
- Early Detection, Prevention and Infections Branch, International Agency for Research on Cancer (IARC/WHO), 150 cours Albert Thomas, CEDEX 08, 69372 Lyon, France; (G.M.C.); (V.T.)
| | - Zigui Chen
- Department of Microbiology, The Chinese University of Hong Kong, Hong Kong, China;
| | - Meredith Yeager
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | - Michael Cullen
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | - Joseph F. Boland
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | - Tina Raine-Bennett
- Division of Research, Kaiser Permanente Northern California, Oakland, CA 94612, USA;
| | - Mia Steinberg
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | - Sara Bass
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | - Yanzi Xiao
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
| | - Vanessa Tenet
- Early Detection, Prevention and Infections Branch, International Agency for Research on Cancer (IARC/WHO), 150 cours Albert Thomas, CEDEX 08, 69372 Lyon, France; (G.M.C.); (V.T.)
| | - Kai Yu
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
| | - Bin Zhu
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
| | - Laurie Burdett
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | - Sevilay Turan
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
| | - Thomas Lorey
- Regional Laboratory, Kaiser Permanente Northern California, Oakland, CA 94710, USA;
| | - Philip E. Castle
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
- Division of Cancer Prevention, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA
| | - Nicolas Wentzensen
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
| | - Robert D. Burk
- Departments of Pediatrics and Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA;
- Department of Epidemiology & Population Health, and Obstetrics, Gynecology and Women’s Health, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Lisa Mirabello
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA; (M.P.); (M.S.); (M.Y.); (M.C.); (J.F.B.); (M.S.); (S.B.); (Y.X.); (K.Y.); (B.Z.); (L.B.); (S.T.); (P.E.C.); (N.W.)
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Role of WDHD1 in Human Papillomavirus-Mediated Oncogenesis Identified by Transcriptional Profiling of E7-Expressing Cells. J Virol 2016; 90:6071-6084. [PMID: 27099318 DOI: 10.1128/jvi.00513-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/16/2016] [Indexed: 01/04/2023] Open
Abstract
UNLABELLED The E7 oncoprotein of the high-risk human papillomavirus (HPV) plays a major role in HPV-induced carcinogenesis. E7 abrogates the G1 cell cycle checkpoint and induces genomic instability, but the mechanism is not fully understood. In this study, we performed RNA sequencing (RNA-seq) to characterize the transcriptional profile of keratinocytes expressing HPV 16 (HPV-16) E7. At the transcriptome level, 236 genes were differentially expressed between E7 and vector control cells. A subset of the differentially expressed genes, most of them novel to E7-expressing cells, was further confirmed by real-time PCR. Of interest, the activities of multiple transcription factors were altered in E7-expressing cells. Through bioinformatics analysis, pathways altered in E7-expressing cells were investigated. The upregulated genes were enriched in cell cycle and DNA replication, as well as in the DNA metabolic process, transcription, DNA damage, DNA repair, and nucleotide metabolism. Specifically, we focused our studies on the gene encoding WDHD1 (WD repeat and high mobility group [HMG]-box DNA-binding protein), one of the genes that was upregulated in E7-expressing cells. WDHD1 is a component of the replisome that regulates DNA replication. Recent studies suggest that WDHD1 may also function as a DNA replication initiation factor as well as a G1 checkpoint regulator. We found that in E7-expressing cells, the steady-state level of WDHD1 protein was increased along with the half-life. Moreover, downregulation of WDHD1 reduced E7-induced G1 checkpoint abrogation and rereplication, demonstrating a novel function for WDHD1. These studies shed light on mechanisms by which HPV induces genomic instability and have therapeutic implications. IMPORTANCE The high-risk HPV types induce cervical cancer and encode an E7 oncoprotein that plays a major role in HPV-induced carcinogenesis. However, the mechanism by which E7 induces carcinogenesis is not fully understood; specific anti-HPV agents are not available. In this study, we performed RNA-seq to characterize transcriptional profiling of keratinocytes expressing HPV-16 E7 and identified more than 200 genes that were differentially expressed between E7 and vector control cells. Through bioinformatics analysis, pathways altered in E7-expressing cells were identified. Significantly, the WDHD1 gene, one of the genes that is upregulated in E7-expressing cells, was found to play an important role in E7-induced G1 checkpoint abrogation and rereplication. These studies shed light on mechanisms by which HPV induces genomic instability and have therapeutic implications.
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Ferenczi A, Gyöngyösi E, Szalmás A, László B, Kónya J, Veress G. Phylogenetic and functional analysis of sequence variation of human papillomavirus type 31 E6 and E7 oncoproteins. INFECTION GENETICS AND EVOLUTION 2016; 43:94-100. [PMID: 27197052 DOI: 10.1016/j.meegid.2016.05.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/13/2016] [Accepted: 05/14/2016] [Indexed: 01/19/2023]
Abstract
High-risk human papillomaviruses (HPV) are the causative agents of cervical and other anogenital cancers as well as a subset of head and neck cancers. The E6 and E7 oncoproteins of HPV contribute to oncogenesis by associating with the tumour suppressor protein p53 and pRb, respectively. For HPV types 16 and 18, intratypic sequence variation was shown to have biological and clinical significance. The functional significance of sequence variation among HPV 31 variants was studied less intensively. HPV 31 variants belonging to different variant lineages were found to have differences in persistence and in the ability to cause high grade cervical intraepithelial neoplasia. In the present study, we started to explore the functional effects of natural sequence variation of HPV 31 E6 and E7 oncoproteins. The E6 variants were tested for their effects on p53 protein stability and transcriptional activity, while the E7 variants were tested for their effects on pRb protein level and also on the transcriptional activity of E2F transcription factors. HPV 31 E7 variants displayed uniform effects on pRb stability and also on the activity of E2F transcription factors. HPV 31 E6 variants had remarkable differences in the ability to inhibit the trans-activation function of p53 but not in the ability to induce the in vivo degradation of p53. Our results indicate that natural sequence variation of the HPV 31 E6 protein may be involved in the observed differences in the oncogenic potential between HPV 31 variants.
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Affiliation(s)
- Annamária Ferenczi
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary
| | - Eszter Gyöngyösi
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary
| | - Anita Szalmás
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary
| | - Brigitta László
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary
| | - József Kónya
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary
| | - György Veress
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary.
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Fan X, Chen JJ. Role of Cdk1 in DNA damage-induced G1 checkpoint abrogation by the human papillomavirus E7 oncogene. Cell Cycle 2015; 13:3249-59. [PMID: 25485505 DOI: 10.4161/15384101.2014.953879] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The high-risk human papillomavirus (HPV) E7 oncogene abrogates DNA damage-induced G1 checkpoint but the mechanism is not fully understood. The G1 kinase Cdk2 is activated in E7-expressing cells. However, whether Cdk2 is required for E7 to abrogate the G1 checkpoint is not known. Accumulating evidence implicates a role for the mitotic Cdk1 in G1/S phase transition in the absence of Cdk2. We therefore examined the expression and requirement of Cdk1 and Cdk2 in the G1 checkpoint abrogation in E7-expressing cells. Although both Cdk1 and Cdk2 were up-regulated in E7-expressing cells upon DNA damage, down-regulation of Cdk1 but not Cdk2 impairs the ability of E7 to abrogate the G1 checkpoint. Our study thus demonstrated an important role for Cdk1 in bypassing the G1 checkpoint in E7-expressing cells. To understand the mechanism by which E7 activates Cdk1, we examined the transcription factor B-Myb. Our studies demonstrated that downregulation of B-Myb reduced the steady-state level of Cdk1 and induced G1 arrest in E7-expressing cells upon DNA damage. In addition, it remains a mystery how E7 promotes cell cycle progression in the presence of Cdk inhibitor p21. As p21 binds Cdk1 with lower affinity than Cdk2, our results suggest a mechanism by which E7 bypasses the inhibitory effect of p21. Nonetheless, our studies demonstrated that p21 still possessed partial ability to arrest cells at G1 phase in E7-expressing cells. These studies shed light on mechanisms by which HPV E7 modulates cell cycle checkpoint.
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Affiliation(s)
- Xueli Fan
- a Department of Medicine ; University of Massachusetts Medical School ; Worcester , MA USA
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Abstract
E7 is an accessory protein that is not encoded by all papillomaviruses. The E7 amino terminus contains two regions of similarity to conserved regions 1 and 2 of the adenovirus E1A protein, which are also conserved in the simian vacuolating virus 40 large tumor antigen. The E7 carboxyl terminus consists of a zinc-binding motif, which is related to similar motifs in E6 proteins. E7 proteins play a central role in the human papillomavirus life cycle, reprogramming the cellular environment to be conducive to viral replication. E7 proteins encoded by the cancer-associated alpha human papillomaviruses have potent transforming activities, which together with E6, are necessary but not sufficient to render their host squamous epithelial cell tumorigenic. This article strives to provide a comprehensive summary of the published research studies on human papillomavirus E7 proteins.
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Integration of HPV6 and downregulation of AKR1C3 expression mark malignant transformation in a patient with juvenile-onset laryngeal papillomatosis. PLoS One 2013; 8:e57207. [PMID: 23437342 PMCID: PMC3577740 DOI: 10.1371/journal.pone.0057207] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 01/21/2013] [Indexed: 11/24/2022] Open
Abstract
Juvenile-onset recurrent respiratory papillomatosis (RRP) is associated with low risk human papillomavirus (HPV) types 6 and 11. Malignant transformation has been reported solely for HPV11-associated RRP in 2–4% of all RRP-cases, but not for HPV6. The molecular mechanisms in the carcinogenesis of low risk HPV-associated cancers are to date unknown. We report of a female patient, who presented with a laryngeal carcinoma at the age of 24 years. She had a history of juvenile-onset RRP with an onset at the age of three and subsequently several hundred surgical interventions due to multiple recurrences of RRP. Polymerase chain reaction (PCR) or bead-based hybridization followed by direct sequencing identified HPV6 in tissue sections of previous papilloma and the carcinoma. P16INK4A, p53 and pRb immunostainings were negative in all lesions. HPV6 specific fluorescence in situ hybridization (FISH) revealed nuclear staining suggesting episomal virus in the papilloma and a single integration site in the carcinoma. Integration-specific amplification of papillomavirus oncogene transcripts PCR (APOT-PCR) showed integration in the aldo-keto reductase 1C3 gene (AKR1C3) on chromosome 10p15.1. ArrayCGH detected loss of the other gene copy as part of a deletion at 10p14-p15.2. Western blot analysis and immunohistochemistry of the protein AKR1C3 showed a marked reduction of its expression in the carcinoma. In conclusion, we identified a novel molecular mechanism underlying a first case of HPV6-associated laryngeal carcinoma in juvenile-onset RRP, i.e. that HPV6 integration in the AKR1C3 gene resulted in loss of its expression. Alterations of AKR1C gene expression have previously been implicated in the tumorigenesis of other (HPV-related) malignancies.
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Gyöngyösi E, Szalmás A, Ferenczi A, Kónya J, Gergely L, Veress G. Effects of human papillomavirus (HPV) type 16 oncoproteins on the expression of involucrin in human keratinocytes. Virol J 2012; 9:36. [PMID: 22333115 PMCID: PMC3296608 DOI: 10.1186/1743-422x-9-36] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 01/11/2012] [Accepted: 02/14/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The human papillomavirus (HPV) life cycle is closely linked to keratinocyte differentiation. Oncogenic HPV infection has been shown to hamper the normal differentiation of keratinocytes; however, the underlying mechanisms responsible for this phenomenon are yet to be clarified. Here, we aimed to study the effects of HPV16 E6 and E7 oncogenes on the expression of involucrin (IVL), an established marker of keratinocyte differentiation, in human foreskin keratinocyte (HFK) cells. RESULTS The differentiation of HFK cells by serum and high calcium significantly increased both the mRNA and the protein levels of IVL. The E6 and E7 oncoproteins of HPV16 together caused strong down-regulation of IVL mRNA and protein both in proliferating and in differentiating HFK cells. To study the effects of HPV oncogenes on the IVL promoter, we made transient transfection assays and luciferase tests and found that HPV 16 E6 but not E7 repressed IVL promoter activity in proliferating HFK cells. The inhibitory effect of HPV 16 E6 on the human IVL promoter could be localised to the proximal regulatory region (PRR) of the gene. CONCLUSIONS These results suggest that the down-regulation of IVL promoter activity by HPV 16 E6 significantly contribute to the inhibition of endogenous IVL expression by the HPV 16 oncoproteins. In contrast, the down-regulation of endogenous IVL expression by HPV16 E7 is probably not caused by a direct and specific effect of E7 on the IVL promoter.
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Affiliation(s)
- Eszter Gyöngyösi
- Department of Medical Microbiology, Medical and Health Science Centre, University of Debrecen, 4032 Debrecen, Nagyerdei krt, 98, Hungary
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Klingelhutz AJ, Roman A. Cellular transformation by human papillomaviruses: lessons learned by comparing high- and low-risk viruses. Virology 2012; 424:77-98. [PMID: 22284986 DOI: 10.1016/j.virol.2011.12.018] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 12/17/2011] [Accepted: 12/27/2011] [Indexed: 12/19/2022]
Abstract
The oncogenic potential of papillomaviruses (PVs) has been appreciated since the 1930s yet the mechanisms of virally-mediated cellular transformation are still being revealed. Reasons for this include: a) the oncoproteins are multifunctional, b) there is an ever-growing list of cellular interacting proteins, c) more than one cellular protein may bind to a given region of the oncoprotein, and d) there is only limited information on the proteins encoded by the corresponding non-oncogenic PVs. The perspective of this review will be to contrast the activities of the viral E6 and E7 proteins encoded by the oncogenic human PVs (termed high-risk HPVs) to those encoded by their non-oncogenic counterparts (termed low-risk HPVs) in an attempt to sort out viral life cycle-related functions from oncogenic functions. The review will emphasize lessons learned from the cell culture studies of the HPVs causing mucosal/genital tract cancers.
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Heller C, Weisser T, Mueller-Schickert A, Rufer E, Hoh A, Leonhardt RM, Knittler MR. Identification of key amino acid residues that determine the ability of high risk HPV16-E7 to dysregulate major histocompatibility complex class I expression. J Biol Chem 2011; 286:10983-97. [PMID: 21321113 DOI: 10.1074/jbc.m110.199190] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
High risk human Papillomavirus (HPV) types are the major causative agents of cervical cancer. Reduced expression of major histocompatibility complex class I (MHC I) on HPV-infected cells might be responsible for insufficient T cell response and contribute to HPV-associated malignancy. The viral gene product required for subversion of MHC I synthesis is the E7 oncoprotein. Although it has been suggested that high and low risk HPVs diverge in their ability to dysregulate MHC I expression, it is not known what sequence determinants of HPV-E7 are responsible for this important functional difference. To investigate this, we analyzed the capability to affect MHC I of a set of chimeric E7 variants containing sequence elements from either high risk HPV16 or low risk HPV11. HPV16-E7, but not HPV11-E7, causes significant diminution of mRNA synthesis and surface presentation of MHC I, which depend on histone deacetylase activity. Our experiments demonstrate that the C-terminal region within the zinc finger domain of HPV-E7 is responsible for the contrasting effects of HPV11- and HPV16-E7 on MHC I. By using different loss- and gain-of-function mutants of HPV11- and HPV16-E7, we identify for the first time a residue variation at position 88 that is highly critical for HPV16-E7-mediated suppression of MHC I. Furthermore, our studies suggest that residues at position 78, 80, and 88 build a minimal functional unit within HPV16-E7 required for binding and histone deacetylase recruitment to the MHC I promoter. Taken together, our data provide new insights into how high risk HPV16-E7 dysregulates MHC I for immune evasion.
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Affiliation(s)
- Corina Heller
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Immunology, Tuebingen, Germany
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Holland D, Hoppe-Seyler K, Schuller B, Lohrey C, Maroldt J, Dürst M, Hoppe-Seyler F. Activation of the enhancer of zeste homologue 2 gene by the human papillomavirus E7 oncoprotein. Cancer Res 2009; 68:9964-72. [PMID: 19047178 DOI: 10.1158/0008-5472.can-08-1134] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The malignant phenotype of human papillomavirus (HPV)-positive cancer cells is maintained by the activity of the viral E6 and E7 genes. Here, we identified the polycomb group gene enhancer of zeste homologue 2 (EZH2) as a novel downstream target for the viral oncogenes in HPV-transformed cells. EZH2 expression was activated by HPV16 E7 at the transcriptional level via E7-mediated release of E2F from pocket proteins. RNA interference analyses showed that continuous EZH2 expression is required for the proliferation of HPV-positive tumor cells by stimulating cell cycle progression at the G1-S boundary. In addition to its growth-promoting activity, EZH2 also contributed to the apoptotic resistance of cervical cancer cells. Furthermore, we found that HPV-positive dysplastic and tumorigenic cervical lesions were characterized by high levels of EZH2 protein in vivo. We conclude that the E7 target gene EZH2 is a major determinant for the proliferation of HPV-positive cancer cells and contributes to their apoptotic resistance. Moreover, EZH2 may serve as a novel therapeutic target for the treatment of cervical cancer.
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Affiliation(s)
- Daniela Holland
- Molecular Therapy of Virus-Associated Cancers (F065), German Cancer Research Center, Heidelberg, Germany
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11
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Abstract
The papillomavirus life cycle is intimately coupled to the differentiation state of the infected epithelium. Since papillomaviruses lack most of the rate-limiting enzymes required for genome synthesis, they need to uncouple keratinocyte differentiation from cell cycle arrest and maintain or reestablish a replication-competent state within terminally differentiated keratinocytes. The human papillomavirus (HPV) E7 protein appears to be a major determinant for this activity and induces aberrant S-phase entry through the inactivation of the retinoblastoma tumor suppressor and related pocket proteins. In addition, E7 can abrogate p21 and p27. Together, this leads to the activation of E2F1 to E2F5, enhanced expression of E2F-responsive genes, and increased cdk2 activity. E2F6 is a pRB-independent, noncanonical member of the E2F transcription factor family that acts as a transcriptional repressor. E2F6 expression is activated in S phase through an E2F-dependent mechanism and thus may provide a negative-feedback mechanism that slows down S-phase progression and/or exit in response to the activation of the other E2F transcription factors. Here, we show that low- and high-risk HPV E7 proteins, as well as simian virus 40 T antigen and adenovirus E1A, can associate with and inactivate the transcriptional repression activity of E2F6, thereby subverting a critical cellular defense mechanism. This may result in the extended S-phase competence of HPV-infected cells. E2F6 is a component of polycomb group complexes, which bind to silenced chromatin and are critical for the maintenance of cell fate. We show that E7-expressing cells show decreased staining for E2F6/polycomb complexes and that this is at least in part dependent on the association with E2F6.
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Gomez-Gutierrez JG, Elpek KG, Montes de Oca-Luna R, Shirwan H, Sam Zhou H, McMasters KM. Vaccination with an adenoviral vector expressing calreticulin-human papillomavirus 16 E7 fusion protein eradicates E7 expressing established tumors in mice. Cancer Immunol Immunother 2007; 56:997-1007. [PMID: 17146630 PMCID: PMC11030956 DOI: 10.1007/s00262-006-0247-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Accepted: 09/26/2006] [Indexed: 12/19/2022]
Abstract
BACKGROUND Cervical cancer remains a leading cause of cancer-related mortality in women, particularly in developing countries. The causal association between genital human papilloma virus (HPV) infection and cervical cancer has been firmly established, and the oncogenic potential of certain HPV types has been clearly demonstrated. Vaccines targeting the oncogenic proteins, E6 and E7 of HPV-16 and -18 are the focus of current vaccine development. Previous studies have shown that calreticulin (CRT) enhances the MHC class I presentation of linked peptide/protein and may serve as an effective vaccination strategy for antigen-specific cancer treatment. METHODS Two replication-deficient adenoviruses, one expressing HPV-16 E7 (Ad-E7) and the other expressing CRT linked to E7 (Ad-CRT/E7), were assessed for their ability to induce cellular immune response and tested for prophylactic and therapeutic effects in an E7-expressing mouse tumor model. RESULTS Vaccination with Ad-CRT/E7 led to a dramatic increase in E7-specific T cell proliferation, interferon (IFN)-gamma-secretion, and cytotoxic activity. Immunization of mice with Ad-CRT/E7 was effective in preventing E7-expressing tumor growth, as well as eradicating established tumors with long-term immunological memory. CONCLUSION Vaccination with an adenoviral vector expressing CRT-E7 fusion protein represents an effective strategy for immunotherapy of cervical cancer in rodents, with possible therapeutic potential in clinical settings.
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Affiliation(s)
- Jorge G. Gomez-Gutierrez
- Louisville, KY USA
- Department of Surgery, University of Louisville School of Medicine; James Graham Brown Cancer Center, 40292 Louisville, KY USA
- Facultad de Ciencias Biológicas, Departamanto de Microbiología e Inmunología, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, NL México
| | - Kutlu G. Elpek
- Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY USA
- Institute for Cellular Therapeutics, University of Louisville School of Medicine, Louisville, KY USA
| | - Roberto Montes de Oca-Luna
- Departamento de Histología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey, NL México
| | - Haval Shirwan
- Louisville, KY USA
- Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY USA
- Institute for Cellular Therapeutics, University of Louisville School of Medicine, Louisville, KY USA
- Microbiology and Immunology, University of Louisville School of Medicine; James Graham Brown Cancer Center, Louisville, KY USA
| | - H. Sam Zhou
- Louisville, KY USA
- Department of Medicine, University of Louisville School of Medicine; James Graham Brown Cancer Center, Louisville, KY USA
- Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY USA
- Microbiology and Immunology, University of Louisville School of Medicine; James Graham Brown Cancer Center, Louisville, KY USA
| | - Kelly M. McMasters
- Louisville, KY USA
- Department of Surgery, University of Louisville School of Medicine; James Graham Brown Cancer Center, 40292 Louisville, KY USA
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13
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Campisi G, Giovannelli L, Calvino F, Matranga D, Colella G, Di Liberto C, Capra G, Leao JC, Lo Muzio L, Capogreco M, D'Angelo M. HPV infection in relation to OSCC histological grading and TNM stage. Evaluation by traditional statistics and fuzzy logic model. Oral Oncol 2006; 42:638-45. [PMID: 16483833 DOI: 10.1016/j.oraloncology.2005.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Accepted: 11/10/2005] [Indexed: 11/22/2022]
Abstract
We aimed to evaluate if in oral squamous cell carcinoma (OSCC) there is a relationship between histological grading (HG), TNM clinical stage and HPV infection; and to study the performance of fuzzy logic compared to traditional statistics, in the analysis of HPV status and correlates of OSCC. In cross-sectional analysis, the study group comprised 63 patients (mean age 68.89 years (SD +/-11.78), range (32-93); males 28 (44.4%), females 35 (55.6%)) with OSCC histologically diagnosed. HPV-DNA was studied in exfoliated oral epithelial cells by nested PCR (MY09/MY11 and GP5+/GP6+ primers). Data were analysed in parallel by traditional statistics with multivariate analysis and a fuzzy logic (FL) technique (membership functions as input, the ANFIS methodology, and the Sugeno's model of first order). HPV infection was detected in 24/63 (38.1%) of OSCC, as being HPV+ve 14/36 (38.9%) in G1, 7/18 (38.9%) in G2, and 3/9 (33.3%) in G3; HPV+ve 8/33 (24.2%) in Stage I, 9/12 (75.0%) in Stage II, 6/11(54.5%) in Stage III, and 1/7 (14.3%) in Stage IV. In both methods of analysis, no significantly increased risk of HPV infection was found for any HG score; whereas, TNM stage II was significantly associated to HPV infection (p=0.004; OR=9.375 (95% CI=2.030:43.30); OR'=11.148 (95% CI=1.951:43.30)), and, in particular, to primary tumour size T2 (p=0.0036; OR=7.812 (95% CI=1.914:31.890); OR'=9.414 (95% CI=1.846:48.013)); FL (% of prevision: 79.8; Root Mean-Square Error (RMSE): 0.29). No association was found between HPV infection and any demographical variable. Our findings show an association between HPV infection with TNM (stage II-T2), but not with histological grading of OSCC. Also, FL seems to be an additional effective tool in analysing the relationship of HPV infection with correlates of OSCC.
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Affiliation(s)
- G Campisi
- Dipartimento di Scienze Stomatologiche, Università di Palermo, Via del Vespro 129, 90127 Palermo, Italy.
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14
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Zhang B, Chen W, Roman A. The E7 proteins of low- and high-risk human papillomaviruses share the ability to target the pRB family member p130 for degradation. Proc Natl Acad Sci U S A 2005; 103:437-42. [PMID: 16381817 PMCID: PMC1326189 DOI: 10.1073/pnas.0510012103] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
High-risk human papillomaviruses (HPVs) (e.g., HPV-16) cause anogenital and head and neck cancers, and low-risk HPVs (e.g., HPV-6) cause benign hyperproliferative disease. The E7 protein of HPV-16 binds all retinoblastoma tumor suppressor protein (pRB) family members with higher affinity than HPV-6E7. The HPV-16 E7 protein has been reported to target pRB family members for degradation and to immortalize cells. Here we tested the hypothesis that the low-risk E7 protein has an intrinsic ability to decrease expression of pRB family members. First, we introduced a high-affinity pRB-binding site into HPV-6 E7 (6E7G22D) and showed that, in human foreskin keratinocytes, HPV-6 E7G22D decreased the level of pRB protein but not pRB mRNA. Second, we analyzed the ability of wild-type HPV-6 E7 to destabilize the other pRB family members, p107 and p130. HPV-6 E7, like HPV-16 E7, decreased the level of p130 protein. This decrease was inhibited by MG132, a proteasome inhibitor. Binding of HPV-6 E7 to p130 was necessary but not sufficient to decrease the level of p130. Furthermore, the destabilization of p130 correlated with a decrease in the expression of involucrin, a differentiation marker. We suggest that the shared activity of HPV-16 E7 and HPV-6 E7 to destabilize p130 and decrease or delay differentiation may be related to the role of E7 in the HPV life cycle. The added ability of HPV-16 E7 to regulate pRB and p107 may be related to oncogenic activity.
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Affiliation(s)
- Benyue Zhang
- Department of Microbiology and Immunology and The Walther Oncology Center, Indiana University School of Medicine and The Walther Cancer Institute, Indianapolis, IN 46202, USA
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15
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Campisi G, Di Fede O, Giovannelli L, Capra G, Greco I, Calvino F, Maria Florena A, Lo Muzio L. Use of fuzzy neural networks in modeling relationships of HPV infection with apoptotic and proliferation markers in potentially malignant oral lesions. Oral Oncol 2005; 41:994-1004. [PMID: 16129653 DOI: 10.1016/j.oraloncology.2005.05.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2005] [Accepted: 05/27/2005] [Indexed: 10/25/2022]
Abstract
To evaluate in oral leukoplakia the relationship between HPV infection and markers of apoptosis (bcl-2, survivin) and proliferation (PCNA), also conditionally to age, gender, smoking and drinking habits of patients, by means of Fuzzy neural networks (FNN) system 21 cases of oral leukopakia, clinically and histologically diagnosed, were examined for HPV DNA presence, bcl-2, survivin and PCNA expression. HPV DNA was investigated in exfoliated oral mucosa cells by nested PCR (nPCR: MY09-MY11/GP5-GP6), and the HPV genotype determined by direct DNA sequencing. All markers were investigated by means of standardised immunohistochemistry procedure. Data were analysed by chi-square test, crude OR and the 95% CI; in blindness, FNN was applied. HPV DNA was found in 8/21 OL (38.1%); survivin, PCNA, and tobacco smoking were associated in univariate analysis (p = 0.04) with HPV DNA status. HPV-18 was the most frequently detected genotype (6/8), followed by HPV-16 (2/8). FNN revealed that survivin and PCNA, both being expressed in all of OL HPV+ve, were associated with HPV infection. In conclusion, the FNN allowed to hypothesise a model of specific variables associated to HPV infection in OL. The relevance of survivin and PCNA suggest that they may be involved in HPV-mediated deregulation of epithelial maturation and, conversely, that HPV may have a role in the expression level of these two markers. FNN system seems to be an effective tool in the analysis of correlates of OL and HPV infection.
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Affiliation(s)
- Giuseppina Campisi
- Department of Oral Sciences, University of Palermo, 90127 Palermo, Italy
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16
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Lo Muzio L, D'Angelo M, Procaccini M, Bambini F, Calvino F, Florena AM, Franco V, Giovannelli L, Ammatuna P, Campisi G. Expression of cell cycle markers and human papillomavirus infection in oral squamous cell carcinoma: Use of fuzzy neural networks. Int J Cancer 2005; 115:717-23. [PMID: 15729691 DOI: 10.1002/ijc.20940] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Our aim was to evaluate in oral squamous cell carcinoma (OSCC) the relationship between some cell cycle markers and HPV infection, conditionally to age, gender and certain habits of patients, and to assess the ability of fuzzy neural networks (FNNs) in building up an adequate predictive model based on logic inference rules. Eighteen cases of OSCC were examined by immunohistochemistry for MIB-1, PCNA and survivin expression; presence of HPV DNA was investigated in exfoliated oral mucosa cells by nested PCR (nPCR, MY09-MY11/GP5-GP6), and HPV genotype was determined by direct DNA sequencing. Data were analyzed by traditional statistics (TS) and FNNs. HPV DNA was found in 9/18 OSCCs (50.0 %) without any significant higher risk of HPV infection with respect to the sociodemographic variables considered (p > 0.2), apart from tobacco smoking, reported in 44.4% of OSCC HPV-positive vs. 100% HPV-negative subjects (p = 0.029). Regarding cell cycle markers, TS and FNN revealed that survivin was expressed significantly more in HPV-negative than in HPV-positive OSCC [root mean-square error (RMSE) = 5.89 x 10(-6), % predicted 100.0]; furthermore, smoking played a protective role for survivin expression in HPV-positive cases (OR = 0.019, 95%CI 0.001-0.723, RMSE = 0.20, % of prevision 94.4). FNN, although on a small sample size, allowed us to confirm data by TS and to hypothesize a different cell cycle pattern for HPV-positive vs. HPV-negative OSCC. In the latter cases, the relevance of apoptotic vs. proliferative markers suggested that they may be related to the different supposed outcome of HPV-negative OSCC and that HPV may have a protective role in the expression level of survivin, especially in tobacco smokers.
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17
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Lo Muzio L, Campisi G, Giovannelli L, Ammatuna P, Greco I, Staibano S, Pannone G, De Rosa G, Di Liberto C, D'Angelo M. HPV DNA and survivin expression in epithelial oral carcinogenesis: a relationship? Oral Oncol 2004; 40:736-41. [PMID: 15172644 DOI: 10.1016/j.oraloncology.2003.11.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Accepted: 11/15/2003] [Indexed: 11/20/2022]
Abstract
HPV has been thought to be involved in the development of several oral diseases, such as premalignant mucosal lesions and oral carcinoma. Survivin is a recently characterized IAP protein, which is abundantly expressed in most solid and haematological malignancies, but undetectable in normal adult tissues. Aim of this study was to investigate survivin expression and HPV presence in oral premalignant lesions and oral carcinoma. 47 samples of oral tissue including 11 squamous cell carcinomas (OSCC), 16 oral leukoplakias (OL) and 20 normal oral mucosa specimens, after investigation of HPV presence by nested PCR (consensus MY/GP primers) and viral genotype identification by direct sequencing were investigated by immunohistochemistry to detect survivin expression. Survivin expression was evident in 4/7 (57.1%) HPV+ and 4/4 (100%) HPV- OSCC, 6/7 (85.7%) HPV+ and 5/9 (55.5%) HPV- OL and in 0/20 (0%) control samples. Data showed high levels of survivin expression in HPV-positive SCCs, even if mean values were lower than HPV-negative ones, which in particular showed survivin expression in 100% of cases. Conversely, survivin expression was greater in HPV+ precancerous lesions than in HPV- ones. Our findings suggest that survivin may be involved in HPV- mediated deregulation during maturation of squamous epithelium through modulation of the apoptotic processes and, conversely, HPV may have a direct or indirect effect on the regulation of the survivin expression level. In particular, the results of this study suggest distinguishing between cancerous and precancerous oral lesions with respect to survivin expression when HPV infection is present. The most unfavourable behaviour is likely to be for the HPV- OSCC.
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Affiliation(s)
- Lorenzo Lo Muzio
- Institute of Dental Sciences, University of Ancona, Via Toti 4, 60100, Italy.
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18
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Fan X, Liu Y, Chen JJ. Activation of c-Myc contributes to bovine papillomavirus type 1 E7-induced cell proliferation. J Biol Chem 2003; 278:43163-8. [PMID: 12937171 DOI: 10.1074/jbc.m306008200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inactivation of the tumor suppressor pRB by the human papillomavirus (HPV) oncoprotein E7 is a mechanism by which HPV promotes cell growth. The bovine papillomavirus type 1 (BPV-1) E7 does not bind pRB efficiently yet is required for full transformation of murine cells by BPV-1. In the present study, we investigated the mechanism of BPV-1 E7-induced cell proliferation. Our studies indicate that expression of BPV-1 E7 induces DNA synthesis and stimulates cells to enter S phase in quiescent cells. The induction of cell proliferation by BPV-1 E7 can occur in the retinoblastoma gene (Rb)-null cells, suggesting an Rb-independent mechanism. Consistent with this observation, BPV-1 E7 does not efficiently activate the transcription of the E2F family of transcription factors (E2F)-responsive promoters. Notably, c-Myc is able to induce cells to enter S phase in quiescent cells through an Rb/E2F-independent pathway. Significantly, c-Myc levels are increased in BPV-1 E7-expressing cells. Moreover, expression of a dominant negative c-Myc mutant inhibited BPV-1 E7-induced DNA synthesis. Consistent with the notion that c-Myc could down-regulate p27 and activate Cdk2, p27 level is decreased while both cyclin A and cyclin E-associated kinase activities are up-regulated in BPV-1 E7-expressing cells. These studies indicate an important role for c-Myc in BPV-1 E7-induced cell proliferation.
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Affiliation(s)
- Xueli Fan
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605-2324, USA
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19
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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: 68] [Impact Index Per Article: 3.1] [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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20
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Hwang SG, Lee D, Kim J, Seo T, Choe J. Human papillomavirus type 16 E7 binds to E2F1 and activates E2F1-driven transcription in a retinoblastoma protein-independent manner. J Biol Chem 2002; 277:2923-30. [PMID: 11713253 DOI: 10.1074/jbc.m109113200] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human papillomavirus (HPV) E7 oncoprotein can immortalize primary human cells and induce tumor formation. These properties of E7 depend on its ability to inhibit the activity of retinoblastoma protein (pRB), which in turn affects E2F function. E2F proteins control the expression of genes involved in differentiation, development, cell proliferation, and apoptosis. By using genetic and biochemical approaches, the present study shows that E7 binds to E2F1 in vivo and in vitro and that both proteins co-localize in the nucleus. Importantly, the binding of the high risk group HPV E7 to E2F1 is tighter than the binding of the low risk group HPV E7 to E2F1. Although E7 of the high risk group HPVs activates E2F1-dependent transcription strongly in C33A or 293T cells, E7 of the low risk group HPVs activates transcription only weakly. By using electrophoretic mobility shift assay, we also showed that E7 binds to E2F1-DNA complexes. Furthermore, we show that these activities of E7 are independent of pRB by using E7 and E2F1 mutants that cannot bind to pRB. Taken together, these data suggest that E7 contributes to the deregulation of pRB-dependent E2F1 repression and to the further activation of E2F1 independently of pRB.
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Affiliation(s)
- Sun Gwan Hwang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
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21
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Münger K, Basile JR, Duensing S, Eichten A, Gonzalez SL, Grace M, Zacny VL. Biological activities and molecular targets of the human papillomavirus E7 oncoprotein. Oncogene 2001; 20:7888-98. [PMID: 11753671 DOI: 10.1038/sj.onc.1204860] [Citation(s) in RCA: 412] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The human papillomavirus (HPV) E7 protein is one of only two viral proteins that remain expressed in HPV-associated human cancers. HPV E7 proteins share structural and functional similarities with oncoproteins encoded by other small DNA tumor viruses such as adenovirus E1A and SV40 large tumor antigen. The HPV E7 protein plays an important role in the viral life cycle by subverting the tight link between cellular differentiation and proliferation in normal epithelium, thus allowing the virus to replicate in differentiating epithelial cells that would have normally withdrawn from the cell division cycle. The transforming activities of E7 largely reflect this important function.
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Affiliation(s)
- K Münger
- Department of Pathology and Harvard Center for Cancer Biology, Harvard Medical School, Boston, MA 02115, USA.
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22
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Overexpression of CCAAT Displacement Protein Represses the Promiscuously Active Proximal gp91phox Promoter. Blood 1999. [DOI: 10.1182/blood.v94.9.3151] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
AbstractCCAAT displacement protein (CDP) is a transcriptional repressor that restricts expression of the gp91phox gene to mature myeloid cells. CDP interacts with multiple sites within the −450 to +12 bp human gp91phox promoter, and down-regulation of CDP DNA-binding activity is required for induction of gp91phox transcription in mature phagocytes. Truncation of the gp91phox promoter to −102 to +12 bp removes 4 CDP-binding sites and reveals a promiscuous promoter activity that is active in some nonphagocytic cells. A cis-element at −90 bp is required for derepressed transcription and serves as a binding site for multiple transcriptional activators. We now report that this element also serves as a binding site for CDP. The affinity of CDP for this element is relatively weak compared with upstream CDP-binding sites within the promoter, consistent with the promiscuous transcriptional activity exhibited by the −102 to +12 bp gp91phox promoter fragment. Further analysis of the proximal promoter reveals an additional weak-affinity CDP-binding site centered at approximately −20 bp. Overexpression of cloned CDP represses the −102 to +12 bp gp91phox promoter, indicating that these proximal CDP-binding sites are functionally significant. The constellation of transcriptional activators and a repressor that interacts with the −90 bp cis-element is identical to that observed for a promoter element at −220 bp, reflecting the highly modular organization of the gp91phoxpromoter. These studies illustrate the complex interplay between transcriptional activators and a repressor that contribute to the myeloid-restricted expression of the gp91phox gene.
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Abstract
CCAAT displacement protein (CDP) is a transcriptional repressor that restricts expression of the gp91phox gene to mature myeloid cells. CDP interacts with multiple sites within the −450 to +12 bp human gp91phox promoter, and down-regulation of CDP DNA-binding activity is required for induction of gp91phox transcription in mature phagocytes. Truncation of the gp91phox promoter to −102 to +12 bp removes 4 CDP-binding sites and reveals a promiscuous promoter activity that is active in some nonphagocytic cells. A cis-element at −90 bp is required for derepressed transcription and serves as a binding site for multiple transcriptional activators. We now report that this element also serves as a binding site for CDP. The affinity of CDP for this element is relatively weak compared with upstream CDP-binding sites within the promoter, consistent with the promiscuous transcriptional activity exhibited by the −102 to +12 bp gp91phox promoter fragment. Further analysis of the proximal promoter reveals an additional weak-affinity CDP-binding site centered at approximately −20 bp. Overexpression of cloned CDP represses the −102 to +12 bp gp91phox promoter, indicating that these proximal CDP-binding sites are functionally significant. The constellation of transcriptional activators and a repressor that interacts with the −90 bp cis-element is identical to that observed for a promoter element at −220 bp, reflecting the highly modular organization of the gp91phoxpromoter. These studies illustrate the complex interplay between transcriptional activators and a repressor that contribute to the myeloid-restricted expression of the gp91phox gene.
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Alloul N, Sherman L. Transcription-modulatory activities of differentially spliced cDNAs encoding the E2 protein of human papillomavirus type 16. J Gen Virol 1999; 80 ( Pt 9):2461-2470. [PMID: 10501502 DOI: 10.1099/0022-1317-80-9-2461] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human papillomavirus (HPV) type 16 expresses a variety of alternatively spliced polycistronic mRNAs encoding the E2 transcription-regulatory protein. These mRNAs initiate at the p97 promoter and contain the 880/2708 (a-type), 880/2581 (a'-type) and 226/2708 (d-type) splice sites upstream from the E2 open reading frame (ORF). Recent studies investigating the translational capacities of partial cDNAs representing three of these mRNAs indicated their abilities to function in E2 protein translation, although at different efficiencies. In the present study, the transcription-regulatory activities of the E2 cDNAs towards the virus long control region (LCR) have been examined. LCR regulation was evaluated in transient transfection assays by using the chloramphenicol acetyltransferase reporter gene linked to the HPV-16 LCR. Transfections were carried out into fibroblast (Cf2Th) and epithelial (C33A) cell lines. It is shown that all three E2 cDNAs transrepressed the virus LCR in a dose-dependent manner. Transrepression was mainly dependent on the function of the E2 ORF and was abolished or markedly reduced by premature termination or truncation of the E2 ORF. Transrepression activities exhibited by the various E2 cDNAs correlated with the previously defined efficiencies of E2 protein translation from the respective templates. The truncated E2 cDNAs exhibited variable low regulatory activities that correlated with the activities of the 5' ORFs contained in each cDNA. The E6I and E1C ORFs transactivated the virus LCR whereas the E6IV cDNA transrepressed LCR activity. Thus, the 5' ORFs contribute in different manners to the overall activities of the polycistronic cDNAs.
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Affiliation(s)
- Nathalie Alloul
- Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel1
| | - Levana Sherman
- Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel1
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