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Wu SY, Lai HT, Sanjib Banerjee N, Ma Z, Santana JF, Wei S, Liu X, Zhang M, Zhan J, Chen H, Posner B, Chen Y, Price DH, Chow LT, Zhou J, Chiang CM. IDR-targeting compounds suppress HPV genome replication via disruption of phospho-BRD4 association with DNA damage response factors. Mol Cell 2024; 84:202-220.e15. [PMID: 38103559 PMCID: PMC10843765 DOI: 10.1016/j.molcel.2023.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 10/14/2023] [Accepted: 11/16/2023] [Indexed: 12/19/2023]
Abstract
Compounds binding to the bromodomains of bromodomain and extra-terminal (BET) family proteins, particularly BRD4, are promising anticancer agents. Nevertheless, side effects and drug resistance pose significant obstacles in BET-based therapeutics development. Using high-throughput screening of a 200,000-compound library, we identified small molecules targeting a phosphorylated intrinsically disordered region (IDR) of BRD4 that inhibit phospho-BRD4 (pBRD4)-dependent human papillomavirus (HPV) genome replication in HPV-containing keratinocytes. Proteomic profiling identified two DNA damage response factors-53BP1 and BARD1-crucial for differentiation-associated HPV genome amplification. pBRD4-mediated recruitment of 53BP1 and BARD1 to the HPV origin of replication occurs in a spatiotemporal and BRD4 long (BRD4-L) and short (BRD4-S) isoform-specific manner. This recruitment is disrupted by phospho-IDR-targeting compounds with little perturbation of the global transcriptome and BRD4 chromatin landscape. The discovery of these protein-protein interaction inhibitors (PPIi) not only demonstrates the feasibility of developing PPIi against phospho-IDRs but also uncovers antiviral agents targeting an epigenetic regulator essential for virus-host interaction and cancer development.
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Affiliation(s)
- Shwu-Yuan Wu
- Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hsien-Tsung Lai
- Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - N Sanjib Banerjee
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Zonghui Ma
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch (UTMB), Galveston, TX 77555, USA
| | - Juan F Santana
- Department of Biochemistry and Molecular Biology, The University of Iowa, Iowa City, IA 52242, USA
| | - Shuguang Wei
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Xisheng Liu
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Meirong Zhang
- State Key Laboratory of Natural Medicines, Department of Organic Chemistry, China Pharmaceutical University, Nanjing 210009, P.R. China
| | - Jian Zhan
- State Key Laboratory of Natural Medicines, Department of Organic Chemistry, China Pharmaceutical University, Nanjing 210009, P.R. China
| | - Haiying Chen
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch (UTMB), Galveston, TX 77555, USA
| | - Bruce Posner
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yadong Chen
- State Key Laboratory of Natural Medicines, Department of Organic Chemistry, China Pharmaceutical University, Nanjing 210009, P.R. China
| | - David H Price
- Department of Biochemistry and Molecular Biology, The University of Iowa, Iowa City, IA 52242, USA
| | - Louise T Chow
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jia Zhou
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch (UTMB), Galveston, TX 77555, USA.
| | - Cheng-Ming Chiang
- Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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Patra S, Patil S, Das S, Bhutia SK. Epigenetic dysregulation in autophagy signaling as a driver of viral manifested oral carcinogenesis. Biochim Biophys Acta Mol Basis Dis 2022; 1868:166517. [DOI: 10.1016/j.bbadis.2022.166517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 07/15/2022] [Accepted: 08/02/2022] [Indexed: 12/24/2022]
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Herbein G, Nehme Z. Polyploid Giant Cancer Cells, a Hallmark of Oncoviruses and a New Therapeutic Challenge. Front Oncol 2020; 10:567116. [PMID: 33154944 PMCID: PMC7591763 DOI: 10.3389/fonc.2020.567116] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/11/2020] [Indexed: 12/19/2022] Open
Abstract
Tumors are renowned as intricate systems that harbor heterogeneous cancer cells with distinctly diverse molecular signatures, sizes and genomic contents. Among those various genomic clonal populations within the complex tumoral architecture are the polyploid giant cancer cells (PGCC). Although described for over a century, PGCC are increasingly being recognized for their prominent role in tumorigenesis, metastasis, therapy resistance and tumor repopulation after therapy. A shared characteristic among all tumors triggered by oncoviruses is the presence of polyploidy. Those include Human Papillomaviruses (HPV), Epstein Barr Virus (EBV), Hepatitis B and C viruses (HBV and HCV, respectively), Human T-cell lymphotropic virus-1 (HTLV-1), Kaposi's sarcoma herpesvirus (KSHV) and Merkel polyomavirus (MCPyV). Distinct viral proteins, for instance Tax for HTLV-1 or HBx for HBV have demonstrated their etiologic role in favoring the appearance of PGCC. Different intriguing biological mechanisms employed by oncogenic viruses, in addition to viruses with high oncogenic potential such as human cytomegalovirus, could support the generation of PGCC, including induction of endoreplication, inactivation of tumor suppressors, development of hypoxia, activation of cellular senescence and others. Interestingly, chemoresistance and radioresistance have been reported in the context of oncovirus-induced cancers, for example KSHV and EBV-associated lymphomas and high-risk HPV-related cervical cancer. This points toward a potential linkage between the previously mentioned players and highlights PGCC as keystone cancer cells in virally-induced tumors. Subsequently, although new therapeutic approaches are actively needed to fight PGCC, attention should also be drawn to reveal the relationship between PGCC and oncoviruses, with the ultimate goal of establishing effective therapeutic platforms for treatment of virus-associated cancers. This review discusses the presence of PGCCs in tumors induced by oncoviruses, biological mechanisms potentially favoring their appearance, as well as their consequent implication at the clinical and therapeutic level.
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Affiliation(s)
- Georges Herbein
- Pathogens & Inflammation/EPILAB Laboratory, EA 4266, University of Franche-Comté, Université Bourgogne Franche-Comté (UBFC), Besançon, France.,Department of Virology, CHRU Besancon, Besançon, France
| | - Zeina Nehme
- Pathogens & Inflammation/EPILAB Laboratory, EA 4266, University of Franche-Comté, Université Bourgogne Franche-Comté (UBFC), Besançon, France.,Faculty of Sciences, Lebanese University, Beirut, Lebanon
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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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Gupta K, Metgud R. Evidences suggesting involvement of viruses in oral squamous cell carcinoma. PATHOLOGY RESEARCH INTERNATIONAL 2013; 2013:642496. [PMID: 24455418 PMCID: PMC3880768 DOI: 10.1155/2013/642496] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 10/21/2013] [Indexed: 12/21/2022]
Abstract
Oral cancer is one of the most common cancers and it constitutes a major health problem particularly in developing countries. Oral squamous cell carcinoma (OSCC) represents the most frequent of all oral neoplasms. Several risk factors have been well characterized to be associated with OSCC with substantial evidences. The etiology of OSCC is complex and involves many factors. The most clearly defined potential factors are smoking and alcohol, which substantially increase the risk of OSCC. However, despite this clear association, a substantial proportion of patients develop OSCC without exposure to them, emphasizing the role of other risk factors such as genetic susceptibility and oncogenic viruses. Some viruses are strongly associated with OSCC while the association of others is less frequent and may depend on cofactors for their carcinogenic effects. Therefore, the exact role of viruses must be evaluated with care in order to improve the diagnosis and treatment of OSCC. Although a viral association within a subset of OSCC has been shown, the molecular and histopathological characteristics of these tumors have yet to be clearly defined.
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Affiliation(s)
- Kanupriya Gupta
- Department of Oral and Maxillofacial Pathology, Pacific Dental College and Hospital, Udaipur, Rajasthan 313001, India
| | - Rashmi Metgud
- Department of Oral and Maxillofacial Pathology, Pacific Dental College and Hospital, Udaipur, Rajasthan 313001, India
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Chow LT, Broker TR. Human papillomavirus infections: warts or cancer? Cold Spring Harb Perspect Biol 2013; 5:cshperspect.a012997. [PMID: 23685995 DOI: 10.1101/cshperspect.a012997] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Human papillomaviruses (HPVs) are prevalent pathogens of mucosal and cutaneous epithelia. Productive infections of squamous epithelia lead to benign hyperproliferative warts, condylomata, or papillomas. Persistent infections of the anogenital mucosa by high-risk HPV genotypes 16 and 18 and closely related types can infrequently progress to high-grade intraepithelial neoplasias, carcinomas-in-situ, and invasive cancers in women and men. HPV-16 is also associated with a fraction of head and neck cancers. We discuss the interactions of the mucosotropic HPVs with the host regulatory proteins and pathways that lead to benign coexistence and enable HPV DNA amplification or, alternatively, to cancers that no longer support viral production.
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Affiliation(s)
- Louise T Chow
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294-0005, USA
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Nonconserved lysine residues attenuate the biological function of the low-risk human papillomavirus E7 protein. J Virol 2011; 85:5546-54. [PMID: 21411531 DOI: 10.1128/jvi.02166-10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mucosotrophic human papillomaviruses (HPVs) are classified as high-risk (HR) or low-risk (LR) genotypes based on their neoplastic properties. We have demonstrated previously that the E7 protein destabilizes p130, a pRb-related pocket protein, thereby promoting S-phase reentry in postmitotic, differentiated keratinocytes of squamous epithelia, and that HR HPV E7 does so more efficiently than LR HPV E7. The E7 proteins of LR HPV-11 and -6b uniquely possess lysine residues following a casein kinase II phosphorylation motif which is critical for the biological function of E7. We now show that mutations of these lysine residues elevated the efficiency of S-phase reentry, independent of their charge. An 11E7 K39,42R mutation moderately increased the association with and the destabilization of p130. Unexpectedly, polyubiquitination on these lysine residues did not attenuate E7 activity, as their mutation caused elevated proteasomal degradation and decreased protein stability. In this regard, the biologically more potent HR HPV E7 proteins were also less stable than the LR HPV E7 proteins. We infer that these lysine residues impede functional protein-protein interactions. A G22D mutation of 11E7 at the pocket protein binding motif possessed augmented efficiency in promoting S-phase reentry and strongly enhanced association with p130 and pRb. The combined effects of these two classes of 11E7 mutations exhibited an efficiency of S-phase reentry comparable to that of HR HPV E7. Thus, these nonconserved residues are primarily responsible for the differential abilities of LR and HR HPV E7 proteins to promote unscheduled DNA replication in organotypic raft cultures.
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Banerjee NS, Wang HK, Broker TR, Chow LT. Human papillomavirus (HPV) E7 induces prolonged G2 following S phase reentry in differentiated human keratinocytes. J Biol Chem 2011; 286:15473-82. [PMID: 21321122 DOI: 10.1074/jbc.m110.197574] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The productive program of human papillomaviruses occurs in differentiated squamous keratinocytes. We have previously shown that HPV-18 DNA amplification initiates in spinous cells in organotypic cultures of primary human keratinocytes during prolonged G(2) phase, as signified by abundant cytoplasmic cyclin B1 (Wang, H. K., Duffy, A. A., Broker, T. R., and Chow, L. T. (2009) Genes Dev. 23, 181-194). In this study, we demonstrated that the E7 protein, which induces S phase reentry in suprabasal cells by destabilizing the p130 pocket protein (Genovese, N. J., Banerjee, N. S., Broker, T. R., and Chow, L. T. (2008) J. Virol. 82, 4862-4873), also elicited extensive G(2) responses. Western blots and indirect immunofluorescence assays were used to probe for host proteins known to control G(2)/M progression. E7 expression induced cytoplasmic accumulation of cyclin B1 and cdc2 in the suprabasal cells. The elevated cdc2 had inactivating phosphorylation on Thr(14) or Tyr(15), and possibly both, due to an increase in the responsible Wee1 and Myt1 kinases. In cells that harbored cytoplasmic cyclin B1 or cdc2, there was also an accumulation of the phosphatase-inactive cdc25C phosphorylated on Ser(216), unable to activate cdc2. Moreover, E7 expression induced elevated expression of phosphorylated ATM (Ser(1981)) and the downstream phosphorylated Chk1, Chk2, and JNKs, kinases known to inactivate cdc25C. Similar results were observed in primary human keratinocyte raft cultures in which the productive program of HPV-18 took place. Collectively, this study has revealed the mechanisms by which E7 induces prolonged G(2) phase in the differentiated cells following S phase induction.
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Affiliation(s)
- N Sanjib Banerjee
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294-0005, USA
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9
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Abstract
Human papillomaviruses (HPVs), members of a very large family of small DNA viruses, cause both benign papillomas and malignant tumors. While most research on these viruses over the past 30 years has focused on their oncogenic properties in the genital tract, they also play an important role in diseases of the upper aerodigestive tract. Rapidly accelerating advances in knowledge have increased our understanding of the biology of these viruses and this knowledge, in turn, is being applied to new approaches to prevent, diagnose, and treat HPV-induced diseases. In this introductory article, we provide an overview of the structure and life cycle of the mucosal HPVs and their interactions with their target tissues and cells. Finally, we provide our thoughts about treatments for HPV-induced diseases, present and future.
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Wang HK, Duffy AA, Broker TR, Chow LT. Robust production and passaging of infectious HPV in squamous epithelium of primary human keratinocytes. Genes Dev 2009; 23:181-94. [PMID: 19131434 DOI: 10.1101/gad.1735109] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Using Cre-loxP-mediated recombination, we established a highly efficient and reproducible system that generates autonomous HPV-18 genomes in primary human keratinocytes (PHKs), the organotypic raft cultures of which recapitulated a robust productive program. While E7 promoted S-phase re-entry in numerous suprabasal differentiated cells, HPV DNA unexpectedly amplified following a prolonged G2 arrest in mid- and upper spinous cells. As viral DNA levels intensified, E7 activity diminished and then extinguished. These cells then exited the cell cycle to undergo virion morphogenesis. High titers of progeny virus generated an indistinguishable productive infection in naïve PHK raft cultures as before, never before achieved until now. An immortalization-defective HPV-18 E6 mutant genome was also characterized for the first time. Numerous cells accumulated p53 protein, without inducing apoptosis, but the productive program was severely curtailed. Complementation of mutant genomes by E6-expressing retrovirus restored proper degradation of p53 as well as viral DNA amplification and L1 production. This system will be invaluable for HPV genetic dissection and serves as a faithful ex vivo model for investigating infections and interventions.
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Affiliation(s)
- Hsu-Kun Wang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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Cell-Cycle Control Protein Expression Is Disrupted in Anogenital Condylomata Infected With Low-Risk Human Papillomavirus Types. J Low Genit Tract Dis 2008; 12:224-31. [DOI: 10.1097/lgt.0b013e318166eff2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Banerjee NS, Genovese NJ, Noya F, Chien WM, Broker TR, Chow LT. Conditionally activated E7 proteins of high-risk and low-risk human papillomaviruses induce S phase in postmitotic, differentiated human keratinocytes. J Virol 2006; 80:6517-24. [PMID: 16775338 PMCID: PMC1488939 DOI: 10.1128/jvi.02499-05] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The productive program of human papillomaviruses (HPVs) in epithelia is tightly linked to squamous differentiation. The E7 proteins of high-risk HPV genotypes efficiently inactivate the pRB family of proteins that control the cell cycle, triggering S phase in suprabasal keratinocytes. This ability has until now not been demonstrated for the low-risk HPV-6 or HPV-11 E7 proteins. An inducible system in which HPV-16 E7 is fused to the ligand binding domain of the human estrogen receptor (ER) was described by Smith-McCune et al. (K. Smith-McCune, D. Kalman, C. Robbins, S. Shivakumar, L. Yuschenkoff, and J. M. Bishop, Proc. Natl. Acad. Sci. USA 96:6999-7004, 1999). In the absence of hormone, E7ER is cytoplasmic, and upon addition of 17beta-estradiol, it translocates to the nucleus. Using organotypic epithelial raft cultures developed from primary human keratinocytes, we show that 16E7ER promotes either S-phase reentry or p21cip1 accumulation in differentiated keratinocytes in a stochastic manner as early as 6 h postinduction with 17beta-estradiol. A vector expressing the ER moiety alone had no effect. These observations prove unequivocally that the E7 protein drives S-phase reentry in postmitotic, differentiated keratinocytes rather than preventing S-phase exit while the cells ascend through the epithelium. HPV-11 E7ER and, much less efficiently, HPV-6 E7ER also promoted S-phase reentry by differentiated cells upon exposure to 17beta-estradiol. S-phase induction required the consensus pRB binding motif. We propose that the elevated nuclear levels of the low-risk HPV E7 protein afforded by the inducible system account for the positive results. These observations are entirely consistent with the fact that low-risk HPV genotypes replicate in the differentiated strata in patient specimens, as do the high-risk HPVs.
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Affiliation(s)
- N Sanjib Banerjee
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294-0005, USA
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Knopp S, Nesland JM, Tropé C, Holm R. p14ARF, a prognostic predictor in HPV-negative vulvar carcinoma. Am J Clin Pathol 2006; 126:266-76. [PMID: 16891203 DOI: 10.1309/e9e8y9wg5qe3lk29] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The present study addressed the impact of human papillomavirus (HPV), p14, and the product of the retinoblastoma gene (pRb) in vulvar carcinoma in relation to other clinicopathologic variables and prognosis. We immunohistochemically studied 217 primary tumors from patients with vulvar carcinoma for the expression of pRb and p14. By the use of in situ hybridization, the primary tumors and 7 lymph node metastases were studied for the presence of HPV-16, HPV-18, HPV-31, and HPV-33 DNA. HPV-infected cases significantly correlated with high expression of p14 (P < .01) and p16 (P < .01). In HPV- cases with high expression of p53, no p14 expression predicted the poorest disease-specific survival (P < .01). For the first time, we have shown that p14 expression indicates longer disease-specific survival in patients with vulvar carcinoma. In patients with HPV- tumors expressing high levels of p53, low p14 indicated the poorest 5-year disease-specific survival.
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Affiliation(s)
- Synne Knopp
- Department of Pathology, and the University of Oslo, Faculty Division, the Norwegian Radium, Hospital, Oslo, Norway
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Nakahara T, Peh WL, Doorbar J, Lee D, Lambert PF. Human papillomavirus type 16 E1circumflexE4 contributes to multiple facets of the papillomavirus life cycle. J Virol 2005; 79:13150-65. [PMID: 16189016 PMCID: PMC1235822 DOI: 10.1128/jvi.79.20.13150-13165.2005] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The life cycle of human papillomaviruses (HPVs) is tightly linked to the differentiation program of the host's stratified epithelia that it infects. E1(circumflex)E4 is a viral protein that has been ascribed multiple biochemical properties of potential biological relevance to the viral life cycle. To identify the role(s) of the viral E1(circumflex)E4 protein in the HPV life cycle, we characterized the properties of HPV type 16 (HPV16) genomes harboring mutations in the E4 gene in NIKS cells, a spontaneously immortalized keratinocyte cell line that when grown in organotypic raft cultures supports the HPV life cycle. We learned that E1(circumflex)E4 contributes to the replication of the viral plasmid genome as a nuclear plasmid in basal cells, in which we also found E1(circumflex)E4 protein to be expressed at low levels. In the suprabasal compartment of organotypic raft cultures harboring E1(circumflex)E4 mutant HPV16 genomes there were alterations in the frequency of suprabasal cells supporting DNA synthesis, the levels of viral DNA amplification, and the degree to which the virus perturbs differentiation. Interestingly, the comparison of the phenotypes of various mutations in E4 indicated that the E1(circumflex)E4 protein-encoding requirements for these various processes differed. These data support the hypothesis that E1(circumflex)E4 is a multifunctional protein and that the different properties of E1(circumflex)E4 contribute to different processes in both the early and late stages of the virus life cycle.
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Affiliation(s)
- Tomomi Nakahara
- McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, 53706, USA
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Vinther J, Rosenstierne MW, Kristiansen K, Norrild B. The 3' region of human papillomavirus type 16 early mRNAs decrease expression. BMC Infect Dis 2005; 5:83. [PMID: 16225671 PMCID: PMC1266366 DOI: 10.1186/1471-2334-5-83] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Accepted: 10/14/2005] [Indexed: 11/27/2022] Open
Abstract
Background High risk human papillomavirus (HR-HPV) infects mucosal surfaces and HR-HPV infection is required for development of cervical cancer. Accordingly, enforced expression of the early HR-HPV proteins can induce immortalisation of human cells. In most cervical cancers and cervical cancer cell lines the HR-HPV double stranded DNA genome has been integrated into the host cell genome. Methods We have used a retroviral GUS reporter system to generate pools of stably transfected HaCaT and SiHa cells. The HPV-16 early sequences that are deleted upon integration of the HPV-16 genome was inserted into the 3' UTR of the reporter mRNA. Pools containing thousands of independent integrations were tested for the steady state levels of the reporter mRNA by Real Time PCR and reporter protein by a GUS enzymatic activity assays. In addition, we tested the cellular distribution and half lives of the reporter mRNAs. The integrity of the reporter mRNAs were tested by northern blotting. Results We show that the 3' region of the HPV-16 early mRNAs (HPV-16 nucleotide (nt.) 2582–4214) act in cis to decrease both mRNA and protein levels. This region seems to affect transcription from the exogenous minimal CMV promoter or processing of the reporter mRNA. The observed repression was most pronounced at the protein level, suggesting that this sequence may also affect translation. For the HPV types: 2, 6, 11, 13, 18, 30, 31, and 35 we have investigated the regulatory effect of the regions corresponding to the HPV-16 nt. 3358–4214. For all types, except HPV-18, the region was found to repress expression by posttranscriptional mechanisms. Conclusion We find that the 3' region of HPV-16 early mRNAs interfere with gene expression. It is therefore possible that the deletion of the 3' part of early HPV-16 mRNAs occurring during cervical oncogenesis could contribute to transformation of cells through deregulation of the viral oncogene synthesis. Moreover, we find that the corresponding region from several other HPV types also repress expression, suggesting that the repression by this region may be a general feature of the HPV life cycle.
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Affiliation(s)
- Jeppe Vinther
- Institute of Molecular Pathology, University of Copenhagen, Blegdamsvej 3C, Bldg. 6.2, DK-2200 Copenhagen N, Denmark
- Institute of Molecular Biology, University of Copenhagen, Universitetsparken 15, Bldg. 10, DK-2100 Copenhagen Ø, Denmark
| | - Maiken W Rosenstierne
- Institute of Molecular Pathology, University of Copenhagen, Blegdamsvej 3C, Bldg. 6.2, DK-2200 Copenhagen N, Denmark
| | - Karen Kristiansen
- Institute of Molecular Pathology, University of Copenhagen, Blegdamsvej 3C, Bldg. 6.2, DK-2200 Copenhagen N, Denmark
- BioCentrum-DTU, Technical University of Denmark, Building 208, DK-2800 Lyngby, Denmark
| | - Bodil Norrild
- Institute of Molecular Pathology, University of Copenhagen, Blegdamsvej 3C, Bldg. 6.2, DK-2200 Copenhagen N, Denmark
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Knight GL, Grainger JR, Gallimore PH, Roberts S. Cooperation between different forms of the human papillomavirus type 1 E4 protein to block cell cycle progression and cellular DNA synthesis. J Virol 2004; 78:13920-33. [PMID: 15564500 PMCID: PMC533915 DOI: 10.1128/jvi.78.24.13920-13933.2004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Posttranslational modification-oligomerization, phosphorylation, and proteolytic cleavage-of the human papillomavirus (HPV) E4 protein occurs as the infected keratinocytes migrate up through the suprabasal wart layers. It has been postulated that these events modify E4 function during the virus life cycle. In HPV type 1 (HPV1)-induced warts, N-terminal sequences are progressively cleaved from the full-length E4 protein (E1(wedge)E4) of 17 kDa to produce a series of polypeptides of 16, 11 and 10 kDa. Here, we have shown that in human keratinocytes, a truncated protein (E4-16K), equivalent to the 16-kDa species, mediated a G(2) arrest in the cell cycle that was dependent on a threonine amino acid in a proline-rich domain of the protein. Reconstitution of cyclin B1 expression in E4-16K cells reversed the G(2) arrest. Expression of E4-16K also induced chromosomal rereplication, and this was associated with aberrant nuclear morphology. Perturbation of the mitotic cell cycle was a biological activity specific to the truncated protein. However, coexpression of the full-length E1(wedge)E4 protein and the truncated E4-16K protein inhibited normal cellular proliferation and cellular DNA rereplication but did not prevent cells from arresting in G(2). Our findings provide the first evidence to support the hypothesis that proteolytic cleavage of the E1(wedge)E4 protein modifies its function. Also, different forms of the HPV1 E4 protein cooperate to negatively influence keratinocyte proliferation. We predict that these distinct biological activities of E4 act to support efficient amplification of the viral genome in suprabasal keratinocytes.
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Affiliation(s)
- Gillian L Knight
- Cancer Research UK Institute for Cancer Studies, University of Birmingham, Vincent Dr., Edgbaston, Birmingham B15 2TT, United Kingdom
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Boccardo E, Noya F, Broker TR, Chow LT, Villa LL. HPV-18 confers resistance to TNF-alpha in organotypic cultures of human keratinocytes. Virology 2004; 328:233-43. [PMID: 15464843 DOI: 10.1016/j.virol.2004.07.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 07/14/2004] [Accepted: 07/22/2004] [Indexed: 11/30/2022]
Abstract
The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) inhibits normal keratinocytes proliferation. However, many human papillomavirus (HPV)-immortalized or transformed cell lines are resistant to TNF-alpha antiproliferative effect. The present study analyzes the effects of TNF-alpha on organotypic cultures of primary human keratinocytes (PHKs) that express HPV-18 oncogenes. Raft cultures prepared with PHKs acutely transfected with HPV-18 whole genome or infected with recombinant retroviruses containing only E6/E7 or E7 were treated with 2 nM TNF-alpha. While BrdU incorporation into basal/parabasal cells of normal PHKs cultures was markedly inhibited by TNF-alpha cultures transfected with HPV-18 whole genome showed proliferation in all cell strata. Furthermore, BrdU incorporation into cultures expressing E6/E7 or E7 was not significantly reduced, indicating that E7 alone confers partial resistance to TNF-alpha. Besides, TNF-alpha treatment did not alter p16ink4a, p21cip1, p27kip1, or cyclin E levels, but did reduce cyclin A and PCNA levels in sensitive cells.
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Affiliation(s)
- Enrique Boccardo
- Ludwig Institute for Cancer Research, 1509-010 São Paulo, SP, Brazil.
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Garner-Hamrick PA, Fostel JM, Chien WM, Banerjee NS, Chow LT, Broker TR, Fisher C. Global effects of human papillomavirus type 18 E6/E7 in an organotypic keratinocyte culture system. J Virol 2004; 78:9041-50. [PMID: 15308700 PMCID: PMC506920 DOI: 10.1128/jvi.78.17.9041-9050.2004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The effects of human papillomavirus type 18 (HPV-18) E6 and E7 proteins on global patterns of host gene expression in primary human keratinocytes grown in organotypic raft culture system were assessed. Primary human keratinocytes were infected with retroviruses that express the wild-type HPV-18 E6 and E7 genes from the native differentiation-dependent HPV enhancer-promoter. Total RNA was isolated from raft cultures and used to generate probes for querying Affymetrix U95A microarrays, which contain >12,500 human gene sequences. Quadruplicate arrays of each E6/E7-transduced and empty vector-transduced samples were analyzed by 16 pairwise comparisons. Transcripts altered in > or =12 comparisons were selected for further analysis. With this approach, HPV-18 E6/E7 expression significantly altered the expression of 1,381 genes. A large increase in transcripts associated with DNA and RNA metabolism was observed, with major increases noted for transcription factors, splicing factors, and DNA replication elements, among others. Multiple genes associated with protein translation were downregulated. In addition, major alterations were found in transcripts associated with the cell cycle and cell differentiation. Our study provides a systematic description of transcript changes brought about by HPV-18 E6/E7 in a physiologically relevant model and should furnish a solid source of information to guide future studies.
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Southern SA, Lewis MH, Herrington CS. Induction of tetrasomy by human papillomavirus type 16 E7 protein is independent of pRb binding and disruption of differentiation. Br J Cancer 2004; 90:1949-54. [PMID: 15138476 PMCID: PMC2409454 DOI: 10.1038/sj.bjc.6601827] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We have demonstrated previously that high-risk human papillomaviruses (HPVs) induce tetrasomy in low-grade squamous intraepithelial lesions of the cervix. In this study we show that the E6 and E7 genes of high-risk HPV-16, but not those of low-risk HPV-6, are independently able to induce tetrasomy when constitutively expressed in proliferating monolayer cultures of primary human keratinocytes. Of seven HPV-16 E7 mutants analysed (H2P, Delta6-10, Delta21-24, C24G, S31G/S32G, A50S and S71I), five were severely impaired in their ability to induce tetrasomy in monolayer and raft culture. Only mutant C24G induced tetrasomy to levels comparable with wild-type E7 in monolayer and raft culture. This mutant shows strongly reduced binding to the retinoblastoma gene product pRb. The casein kinase II phosphorylation defective mutant S31G/S32G induced tetrasomy to levels comparable with wild-type E7 in raft culture, but not in monolayer culture, and induction of tetrasomy did not correlate with raft morphology. These results indicate that pRb protein binding is not required for HPV-16 E7 associated tetrasomy and that tetrasomy is not directly related to the ability of this protein to disrupt keratinocyte differentiation.
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Affiliation(s)
- S A Southern
- Department of Pathology, University of Liverpool, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - M H Lewis
- Department of Pathology, University of Liverpool, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - C S Herrington
- Department of Pathology, University of Liverpool, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
- Bute Medical School, University of St Andrews, St Andrews KY16 9TS, UK
- Department of Pathology, University of Liverpool, Duncan Building, Daulby Street, Liverpool L69 3GA, UK. E-mail:
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Sacco A, Siepi F, Crescenzi M. HPV E7 expression in skeletal muscle cells distinguishes initiation of the postmitotic state from its maintenance. Oncogene 2003; 22:4027-34. [PMID: 12821937 DOI: 10.1038/sj.onc.1206353] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The E7 oncogene is an essential tool used by papillomaviruses to interfere with the cell cycle and cellular differentiation. We investigated the effects of E7 expression on both cellular functions in skeletal muscle cells, a terminally differentiating system. When expressed in myoblasts, E7 impaired differentiation only partially, but allowed continuation of DNA synthesis during and after differentiation. Surprisingly, E7 expression in terminally differentiated myotubes could not reactivate DNA synthesis even though the oncogene bound the retinoblastoma protein, reduced its levels, and increased E2F transcriptional activity. Despite the high cyclin E protein levels induced by E7, the myotubes remained devoid of cyclin E-associated kinase activity. Enforcement of such activity in the presence of E7 brought myotubes into S phase. These results show that E7, unlike other DNA tumor-virus oncogenes, cannot reactivate the cell cycle in postmitotic myotubes. In contrast, E7 allows significant differentiation to occur in the presence of persisting DNA synthesis. These observations distinguish E7 from other functionally related oncogenes and bear significance for the understanding of the natural life cycle of human papillomaviruses. The fact that E7 alone inhibits the initiation but not the maintenance of the postmitotic state indicates that the mechanisms underlying these two functions are at least partially distinct.
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Affiliation(s)
- Alessandra Sacco
- Laboratory of Comparative Toxicology and Ecotoxicology, Istituto Superiore di Sanita, Viale Regina Elena, 299, 00161 Rome, Italy
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Noya F, Balagué C, Banerjee NS, Curiel DT, Broker TR, Chow LT. Activation of adenovirus early promoters and lytic phase in differentiated strata of organotypic cultures of human keratinocytes. J Virol 2003; 77:6533-40. [PMID: 12743310 PMCID: PMC155017 DOI: 10.1128/jvi.77.11.6533-6540.2003] [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: 11/20/2022] Open
Abstract
Human oncolytic adenoviruses have been used in clinical trials targeting cancers of epithelial origin. To gain a better understanding of the infectious cycle of adenovirus in normal human squamous tissues, we examined the viral infection process in organotypic cultures of primary human keratinocytes. We show that for the infection to occur, wounding of the epithelium is required. In addition, infection appears to initiate at the basal or parabasal cells that express the high-affinity coxsackievirus-adenovirus receptor, CAR, whereas the productive phase takes place in differentiated cells. This is due, at least in part, to the differentiation-dependent activation of the E1A and E2A early promoters and E4 promoters. We also show that adenovirus infection triggers a response mediated by the abnormal accumulation of cyclin E and p21cip1 proteins similar to the one previously observed in human papillomavirus-infected tissues. However, the virus seems to be able to overcome it, at least partially.
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Affiliation(s)
- Francisco Noya
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 35294-0005, USA
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Helt AM, Funk JO, Galloway DA. Inactivation of both the retinoblastoma tumor suppressor and p21 by the human papillomavirus type 16 E7 oncoprotein is necessary to inhibit cell cycle arrest in human epithelial cells. J Virol 2002; 76:10559-68. [PMID: 12239337 PMCID: PMC136576 DOI: 10.1128/jvi.76.20.10559-10568.2002] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The human papillomavirus (HPV) type 16 E7 oncoprotein must inactivate the retinoblastoma tumor suppressor (Rb) pathway to bypass G(1) arrest. However, E7 C-terminal mutants that were able to inactivate Rb were unable to bypass DNA damage-induced G(1) arrest and keratinocyte senescence, suggesting that the E7 C terminus may target additional G(1) regulators. The E7 C-terminal mutant proteins E7 CVQ68-70AAA and E7 Delta79-83 (deletion of positions 79 through 83) were further tested in several models of cell cycle arrest associated with elevated levels of p21. C-terminal mutations rendered E7 unable to induce S phase and endoreduplication in differentiated keratinocytes and rendered it less efficient in delaying senescence of human mammary epithelial cells. Interestingly, when cell cycle arrest was induced with a peptide form of p21, the E7 C-terminal mutants were deficient in overcoming arrest, whereas a mutant defective in Rb binding was competent in inhibiting G(1) arrest. These results suggest that the inactivation of both p21 and Rb by E7 contributes to subversion of cell cycle control in normal human epithelia but that neither p21 nor Rb inactivation alone is sufficient.
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Affiliation(s)
- Anna-Marija Helt
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA
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Noya F, Chien WM, Wu X, Banerjee NS, Kappes JC, Broker TR, Chow LT. The promoter of the human proliferating cell nuclear antigen gene is not sufficient for cell cycle-dependent regulation in organotypic cultures of keratinocytes. J Biol Chem 2002; 277:17271-80. [PMID: 11877408 DOI: 10.1074/jbc.m112441200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The proliferating cell nuclear antigen (PCNA) is essential for DNA replication of mammalian cells and their small DNA tumor viruses. The mechanism of the cell cycle-dependent regulation of the human PCNA promoter is not clear despite extensive investigations. In this report, we employed organotypic cultures of primary human keratinocytes, which closely resemble native skin comprising both proliferating and postmitotic, differentiated cells, to examine the cell cycle-dependent regulation of the human PCNA gene (hPCNA) in the absence or presence of the human papillomavirus type 18 (HPV-18) E7 protein. HPV-18 E7 promotes S phase re-entry in post-mitotic differentiated keratinocytes by abrogating the transcription repression of E2F transcription factors by the retinoblastoma susceptibility protein, pRb. We demonstrated that E7 reactivated the transcription of the endogenous hPCNA in differentiated keratinocytes. In contrast, with or without E7, the expression of a transduced hPCNA promoter-driven reporter did not correlate with that of the endogenous hPCNA gene in either proliferating or differentiated cells. Moreover, in Chinese hamster ovary and L-cells, HPV E7 and the adenovirus E1A protein repressed the transduced hPCNA promoter, but both activated an extended promoter construct spanning the first intron. Mutations of two E2F sites in the intron reduced the basal activity and abolished the response to E7 or E1A. Promoter repression or activation required the CR2 domain of E7 and, to a lesser extent, CR1 as well. However, in organotypic cultures, this extended promoter construct failed to recapitulate the cell cycle-dependent regulation of the endogenous hPCNA gene. Only when a full-length Myc-tagged hPCNA spanning the 5' promoter and all exons and introns was used was the native pattern of expression largely restored, indicative of the complexity of its regulation.
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Affiliation(s)
- Francisco Noya
- Department of Biochemistry, University of Alabama at Birmingham, 35294-0005, USA
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