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Moujane S, Bouadid I, Bouymajane A, Younes FZ, Benlyas M, Mohammed B, Cacciola F, Vinci RL, Tropea A, Mondello L, Altemimi AB, Eddouks M, Moualij B. Biochemical and toxicity evaluation of Retama sphaerocarpa extracts and in-silico investigation of phenolic compounds as potential inhibitors against HPV16 E6 oncoprotein. Fitoterapia 2024; 175:105923. [PMID: 38554886 DOI: 10.1016/j.fitote.2024.105923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 03/22/2024] [Accepted: 03/23/2024] [Indexed: 04/02/2024]
Abstract
Cervical cancer is a type of cancer which affects the cervix cells. The conventional treatments for cervical cancer including surgery, chemotherapy, and radiotherapy are only effective in premature stages and less effective in late stages of this tumor. Therefore, the therapeutic strategies based on biologically active substances from plants are needed to develop for the treatment of cervical cancer. The aim of the present study was to assess in vivo toxicity, hematological and biochemical blood parameters in Wistar rats fed Retama sphaerocarpa aqueous leaf extract (RS-AE), as well as to perform in silico molecular docking studies and dynamic simulation of phenolic compounds against HPV16 oncoprotein E6 in order to identify potential inhibitors. RS-AE was found not to induce acute or sub-acute oral toxicity or significant alterations in hematological and biochemical blood parameters in Wistar rats. A total of 11 phenolic compounds were identified in RS-AE, including dihydrodaidzein glucuronide, chrysoperiol pentoside, genistin and vitexin, which turned out to have the highest binding affinity to HPV16 oncoprotein E6. Based on these results, these RS-AE phenolic compounds could be used as natural drugs against the HPV16 E6 oncoprotein.
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Zheng K, Egawa N, Shiraz A, Katakuse M, Okamura M, Griffin HM, Doorbar J. The Reservoir of Persistent Human Papillomavirus Infection; Strategies for Elimination Using Anti-Viral Therapies. Viruses 2022; 14:214. [PMID: 35215808 PMCID: PMC8876702 DOI: 10.3390/v14020214] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 02/06/2023] Open
Abstract
Human Papillomaviruses have co-evolved with their human host, with each of the over 200 known HPV types infecting distinct epithelial niches to cause diverse disease pathologies. Despite the success of prophylactic vaccines in preventing high-risk HPV infection, the development of HPV anti-viral therapies has been hampered by the lack of enzymatic viral functions, and by difficulties in translating the results of in vitro experiments into clinically useful treatment regimes. In this review, we discuss recent advances in anti-HPV drug development, and highlight the importance of understanding persistent HPV infections for future anti-viral design. In the infected epithelial basal layer, HPV genomes are maintained at a very low copy number, with only limited viral gene expression; factors which allow them to hide from the host immune system. However, HPV gene expression confers an elevated proliferative potential, a delayed commitment to differentiation, and preferential persistence of the infected cell in the epithelial basal layer, when compared to their uninfected neighbours. To a large extent, this is driven by the viral E6 protein, which functions in the HPV life cycle as a modulator of epithelial homeostasis. By targeting HPV gene products involved in the maintenance of the viral reservoir, there appears to be new opportunities for the control or elimination of chronic HPV infections.
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He H, Qiao D, Zhang L, Yao Y, Shao H, Qin A, Qian K. Antiviral Effect of Lithium Chloride on Replication of Marek's Disease Virus in Chicken Embryonic Fibroblasts. Int J Mol Sci 2021; 22:12375. [PMID: 34830257 PMCID: PMC8623539 DOI: 10.3390/ijms222212375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 11/09/2021] [Accepted: 11/15/2021] [Indexed: 11/16/2022] Open
Abstract
To investigate the antiviral effect of lithium chloride (LiCl) on the replication of Marek's disease virus (MDV) in chicken embryonic fibroblast (CEF) cells, real-time PCR, Western blotting, plaque counting, and indirect immunofluorescence experiments were performed at different time points of LiCl treated CEF cells with virus infection. The results demonstrated that LiCl could affect multiple steps of virus replication and inhibit viral gene expression and protein synthesis in a dose- and time-dependent manner. Moreover, LiCl could directly affect viral infectivity as well. In addition, LiCl significantly affected the gene expression of IFN-β related genes in virus-infected cells. These results indicate that LiCl significantly inhibits MDV replication and proliferation in CEF cells and it has the potential to be used as an antiviral agent against MDV.
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Celegato M, Messa L, Goracci L, Mercorelli B, Bertagnin C, Spyrakis F, Suarez I, Cousido-Siah A, Travé G, Banks L, Cruciani G, Palù G, Loregian A. A novel small-molecule inhibitor of the human papillomavirus E6-p53 interaction that reactivates p53 function and blocks cancer cells growth. Cancer Lett 2019; 470:115-125. [PMID: 31693922 DOI: 10.1016/j.canlet.2019.10.046] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 10/29/2019] [Accepted: 10/30/2019] [Indexed: 12/16/2022]
Abstract
Despite prophylactic vaccination campaigns, human papillomavirus (HPV)-induced cancers still represent a major medical issue for global population, thus specific anti-HPV drugs are needed. Since the ability of HPV E6 oncoprotein to promote p53 degradation is linked to tumor progression, E6 has been proposed as an ideal target for cancer treatment. Using the crystal structure of the E6/E6AP/p53 complex, we performed an in silico screening of small-molecule libraries against a highly conserved alpha-helix in the N-terminal domain of E6 involved in the E6-p53 interaction. We discovered a compound able to inhibit the E6-mediated degradation of p53 through disruption of E6-p53 binding both in vitro and in cells. This compound could restore p53 intracellular levels and transcriptional activity, reduce the viability and proliferation of HPV-positive cancer cells, and block 3D cervospheres formation. Mechanistic studies revealed that the compound anti-tumor activity mainly relies on induction of cell cycle arrest and senescence. Our data demonstrate that the disruption of the direct E6-p53 interaction can be obtained with a small-molecule compound leading to specific antitumoral activity in HPV-positive cancer cells and thus represents a new approach for anti-HPV drug development.
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Jubair L, Fallaha S, McMillan NAJ. Systemic Delivery of CRISPR/Cas9 Targeting HPV Oncogenes Is Effective at Eliminating Established Tumors. Mol Ther 2019; 27:2091-2099. [PMID: 31537455 DOI: 10.1016/j.ymthe.2019.08.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/30/2019] [Accepted: 08/21/2019] [Indexed: 12/15/2022] Open
Abstract
The recent advancements in CRISPR/Cas9 engineering have resulted in the development of more targeted and potentially safer gene therapies. The challenge in the cancer setting is knowing the driver oncogenes responsible, and the translation of these therapies is hindered by effective and safe delivery methods to target organs with minimal systemic toxicities, on-target specificity of gene editing, and demonstrated lack of long-term adverse events. Using a model system based on cervical cancer, which is driven by the ongoing expression of the human papillomavirus E6 and E7 proteins, we show that CRISPR/Cas9 delivered systemically in vivo using PEGylated liposomes results in tumor elimination and complete survival in treated animals. We compared treatment and editing efficiency of two Cas9 variants, wild-type (WT) Cas9 and the highly specific FokI-dCas9, and showed that the latter was not effective. We also explored high-fidelity repair but found that repair was inefficient, occurring in 6%-8% of cells, whereas non-homologous end joining (NHEJ) was highly efficient, occurring in ∼80% of the cells. Finally, we explored the post gene-editing events in tumors and showed that cell death is induced by apoptosis. Overall, our work demonstrates that in vivo CRISPR/Cas editing treatment of preexisting tumors is completely effective despite the large payloads.
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Yan H, Foo SS, Chen W, Yoo JS, Shin WJ, Wu C, Jung JU. Efficient Inhibition of Human Papillomavirus Infection by L2 Minor Capsid-Derived Lipopeptide. mBio 2019; 10:e01834-19. [PMID: 31387913 PMCID: PMC6686047 DOI: 10.1128/mbio.01834-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 07/16/2019] [Indexed: 01/05/2023] Open
Abstract
The amino (N)-terminal region of human papillomavirus (HPV) minor capsid protein (L2) is a highly conserved region which is essential for establishing viral infection. Despite its importance in viral infectivity, the role of the HPV N-terminal domain has yet to be fully characterized. Using fine mapping analysis, we identified a 36-amino-acid (aa) peptide sequence of the L2 N terminus, termed L2N, that is critical for HPV infection. Ectopic expression of L2N with the transmembrane sequence on the target cell surface conferred resistance to HPV infection. Additionally, L2N peptide with chemical or enzymatic lipidation at the carboxyl (C) terminus efficiently abrogated HPV infection in target cells. Among the synthetic L2N lipopeptides, a stearoylated lipopeptide spanning aa 13 to 46 (13-46st) exhibited the most potent anti-HPV activity, with a half-maximal inhibitory concentration (IC50) of ∼200 pM. Furthermore, we demonstrated that the 13-46st lipopeptide inhibited HPV entry by blocking trans-Golgi network retrograde trafficking of virion particles, leading to rapid degradation. Fundamentally, the inhibitory effect of L2N lipopeptides appeared to be evolutionarily conserved, as they showed cross-type inhibition among various papillomaviruses. In conclusion, our findings provide new insights into the critical role of the L2N sequence in the HPV entry mechanism and identify the therapeutic potential of L2N lipopeptide as an effective anti-HPV agent.IMPORTANCE HPV is a human oncogenic virus that causes a major public health problem worldwide, which is responsible for approximately 5% of total human cancers and almost all cases of cervical cancers. HPV capsid consists of two structure proteins, the major capsid L1 protein and the minor capsid L2 protein. While L2 plays critical roles during the viral life cycle, the molecular mechanism in viral entry remains elusive. Here, we performed fine mapping of the L2 N-terminal region and defined a short 36-amino-acid peptide, called L2N, which is critical for HPV infection. Specifically, L2N peptide with carboxyl-terminal lipidation acted as a potent and cross-type HPV inhibitor. Taken together, data from our study highlight the essential role of the L2N sequence at the early step of HPV entry and suggests the L2N lipopeptide as a new strategy to broadly prevent HPV infection.
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Ricci-López J, Vidal-Limon A, Zunñiga M, Jimènez VA, Alderete JB, Brizuela CA, Aguila S. Molecular modeling simulation studies reveal new potential inhibitors against HPV E6 protein. PLoS One 2019; 14:e0213028. [PMID: 30875378 PMCID: PMC6420176 DOI: 10.1371/journal.pone.0213028] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 02/13/2019] [Indexed: 11/18/2022] Open
Abstract
High-risk strains of human papillomavirus (HPV) have been identified as the etiologic agent of some anogenital tract, head, and neck cancers. Although prophylactic HPV vaccines have been approved; it is still necessary a drug-based treatment against the infection and its oncogenic effects. The E6 oncoprotein is one of the most studied therapeutic targets of HPV, it has been identified as a key factor in cell immortalization and tumor progression in HPV-positive cells. E6 can promote the degradation of p53, a tumor suppressor protein, through the interaction with the cellular ubiquitin ligase E6AP. Therefore, preventing the formation of the E6-E6AP complex is one of the main strategies to inhibit the viability and proliferation of infected cells. Herein, we propose an in silico pipeline to identify small-molecule inhibitors of the E6-E6AP interaction. Virtual screening was carried out by predicting the ADME properties of the molecules and performing ensemble-based docking simulations to E6 protein followed by binding free energy estimation through MM/PB(GB)SA methods. Finally, the top-three compounds were selected, and their stability in the E6 docked complex and their effect in the inhibition of the E6-E6AP interaction was corroborated by molecular dynamics simulation. Therefore, this pipeline and the identified molecules represent a new starting point in the development of anti-HPV drugs.
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Aggarwal C, Cohen RB, Morrow MP, Kraynyak KA, Sylvester AJ, Knoblock DM, Bauml JM, Weinstein GS, Lin A, Boyer J, Sakata L, Tan S, Anton A, Dickerson K, Mangrolia D, Vang R, Dallas M, Oyola S, Duff S, Esser M, Kumar R, Weiner D, Csiki I, Bagarazzi ML. Immunotherapy Targeting HPV16/18 Generates Potent Immune Responses in HPV-Associated Head and Neck Cancer. Clin Cancer Res 2018; 25:110-124. [PMID: 30242022 DOI: 10.1158/1078-0432.ccr-18-1763] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 08/10/2018] [Accepted: 09/19/2018] [Indexed: 12/11/2022]
Abstract
PURPOSE Clinical responses with programmed death (PD-1) receptor-directed antibodies occur in about 20% of patients with advanced head and neck squamous cell cancer (HNSCCa). Viral neoantigens, such as the E6/E7 proteins of HPV16/18, are attractive targets for therapeutic immunization and offer an immune activation strategy that may be complementary to PD-1 inhibition. PATIENTS AND METHODS We report phase Ib/II safety, tolerability, and immunogenicity results of immunotherapy with MEDI0457 (DNA immunotherapy targeting HPV16/18 E6/E7 with IL12 encoding plasmids) delivered by electroporation with CELLECTRA constant current device. Twenty-two patients with locally advanced, p16+ HNSCCa received MEDI0457. RESULTS MEDI0457 was associated with mild injection site reactions, but no treatment-related grade 3-5 adverse events (AE) were noted. Eighteen of 21 evaluable patients showed elevated antigen-specific T-cell activity by IFNγ ELISpot, and persistent cellular responses surpassing 100 spot-forming units (SFUs)/106 peripheral blood mononuclear cells (PBMCs) were noted out to 1 year. Induction of HPV-specific CD8+ T cells was observed. MEDI0457 shifted the CD8+/FoxP3+ ratio in 4 of 5 post immunotherapy tumor samples and increased the number of perforin+ immune infiltrates in all 5 patients. One patient developed metastatic disease and was treated with anti-PD-1 therapy with a rapid and durable complete response. Flow-cytometric analyses revealed induction of HPV16-specific PD-1+ CD8+ T cells that were not found prior to MEDI0547 (0% vs. 1.8%). CONCLUSIONS These data demonstrate that MEDI0457 can generate durable HPV16/18 antigen-specific peripheral and tumor immune responses. This approach may be used as a complementary strategy to PD-1/PD-L1 inhibition in HPV-associated HNSCCa to improve therapeutic outcomes.
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Bender Ignacio RA, Lin LL, Rajdev L, Chiao E. Evolving Paradigms in HIV Malignancies: Review of Ongoing Clinical Trials. J Natl Compr Canc Netw 2018; 16:1018-1026. [PMID: 30099376 PMCID: PMC6109631 DOI: 10.6004/jnccn.2018.7064] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/23/2018] [Indexed: 12/19/2022]
Abstract
This review highlights current interventional clinical trials for HIV-associated malignancies (HIVAMs), with emphasis on 4 mechanistic areas: immunomodulatory therapies and gene therapies, including immune checkpoint inhibitors; cytotoxic therapies; novel tumor-targeted and virally targeted therapies in both AIDS-defining and non-AIDS-defining cancers (NADC); and other screening or topical/ablative interventions. A search on ClinicalTrials.gov located 35 trials, including 12 immunomodulatory or gene therapy trials, 6 cytotoxic therapy trials, 10 trials of therapies with tumor or viral molecular targets, and 7 trials evaluating screening interventions or topical or ablative therapies. Study drugs, mechanisms, and outcomes of interest, including future directions, are discussed. Targeted therapies and immunotherapies address not only the tumor but underlying viral oncogens, including possible benefits on HIV-specific immunologic control. The resulting science from the trials listed in this review will provide important translational breakthroughs for people living with HIV (PLWH) and cancer. We highlight disease-specific challenges that could be addressed in future studies, including testing the safety and efficacy of cutting-edge immunotherapy and targeted treatments used in the general cancer population, and improving gaps in knowledge and practice for cancer screening and its treatment, especially in low-resource regions. Additional important considerations include identification of novel therapies for virally mediated tumors that disproportionally present in PLWH, how to treat persons with HIVAM and advanced immunosuppression, and how to comanage both diseases in antiretroviral therapy-naïve persons and those receiving care in settings where supportive therapies for hematologic toxicities and infections are limited. Current and future clinical trials should address needs of both resource-replete and -limited regions, as well as cancers that are uncommon in or respond differently to HIV-negative populations (eg, Kaposi sarcoma or anal cancer), in addition to an increased focus on NADCs not traditionally linked with HIV, such as lung or gastrointestinal tumors.
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Sedan Y, Marcu O, Lyskov S, Schueler-Furman O. Peptiderive server: derive peptide inhibitors from protein-protein interactions. Nucleic Acids Res 2016; 44:W536-41. [PMID: 27141963 PMCID: PMC4987930 DOI: 10.1093/nar/gkw385] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/25/2016] [Accepted: 04/26/2016] [Indexed: 02/05/2023] Open
Abstract
The Rosetta Peptiderive protocol identifies, in a given structure of a protein-protein interaction, the linear polypeptide segment suggested to contribute most to binding energy. Interactions that feature a 'hot segment', a linear peptide with significant binding energy compared to that of the complex, may be amenable for inhibition and the peptide sequence and structure derived from the interaction provide a starting point for rational drug design. Here we present a web server for Peptiderive, which is incorporated within the ROSIE web interface for Rosetta protocols. A new feature of the protocol also evaluates whether derived peptides are good candidates for cyclization. Fast computation times and clear visualization allow users to quickly assess the interaction of interest. The Peptiderive server is available for free use at http://rosie.rosettacommons.org/peptiderive.
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Rietz A, Petrov DP, Bartolowits M, DeSmet M, Davisson VJ, Androphy EJ. Molecular Probing of the HPV-16 E6 Protein Alpha Helix Binding Groove with Small Molecule Inhibitors. PLoS One 2016; 11:e0149845. [PMID: 26915086 PMCID: PMC4767726 DOI: 10.1371/journal.pone.0149845] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 02/05/2016] [Indexed: 12/30/2022] Open
Abstract
The human papillomavirus (HPV) HPV E6 protein has emerged as a central oncoprotein in HPV-associated cancers in which sustained expression is required for tumor progression. A majority of the E6 protein interactions within the human proteome use an alpha-helix groove interface for binding. The UBE3A/E6AP HECT domain ubiquitin ligase binds E6 at this helix-groove interface. This enables formation of a trimeric complex with p53, resulting in destruction of this tumor suppressor. While recent x-ray crystal structures are useful, examples of small molecule probes that can modulate protein interactions at this interface are limited. To develop insights useful for potential structure-based design of ligands for HPV E6, a series of 2,6-disubstituted benzopyranones were prepared and tested as competitive antagonists of E6-E6AP helix-groove interactions. These small molecule probes were used in both binding and functional assays to evaluate recognition features of the E6 protein. Evidence for an ionic functional group interaction within the helix groove was implicated by the structure-activity among the highest affinity ligands. The molecular topographies of these protein-ligand interactions were evaluated by comparing the binding and activities of single amino acid E6 mutants with the results of molecular dynamic simulations. A group of arginine residues that form a rim-cap over the E6 helix groove offer compensatory roles in binding and recognition of the small molecule probes. The flexibility and impact on the overall helix-groove shape dictated by these residues offer new insights for structure-based targeting of HPV E6.
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Zanier K, Stutz C, Kintscher S, Reinz E, Sehr P, Bulkescher J, Hoppe-Seyler K, Travé G, Hoppe-Seyler F. The E6AP binding pocket of the HPV16 E6 oncoprotein provides a docking site for a small inhibitory peptide unrelated to E6AP, indicating druggability of E6. PLoS One 2014; 9:e112514. [PMID: 25383876 PMCID: PMC4226571 DOI: 10.1371/journal.pone.0112514] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 10/03/2014] [Indexed: 12/11/2022] Open
Abstract
The HPV E6 oncoprotein maintains the malignant phenotype of HPV-positive cancer cells and represents an attractive therapeutic target. E6 forms a complex with the cellular E6AP ubiquitin ligase, ultimately leading to p53 degradation. The recently elucidated x-ray structure of a HPV16 E6/E6AP complex showed that HPV16 E6 forms a distinct binding pocket for E6AP. This discovery raises the question whether the E6AP binding pocket is druggable, i. e. whether it provides a docking site for functional E6 inhibitors. To address these issues, we performed a detailed analysis of the HPV16 E6 interactions with two small peptides: (i) E6APpep, corresponding to the E6 binding domain of E6AP, and (ii) pep11**, a peptide that binds to HPV16 E6 and, in contrast to E6APpep, induces apoptosis, specifically in HPV16-positive cancer cells. Surface plasmon resonance, NMR chemical shift perturbation, and mammalian two-hybrid analyses coupled to mutagenesis indicate that E6APpep contacts HPV16 E6 amino acid residues within the E6AP pocket, both in vitro and intracellularly. Many of these amino acids were also important for binding to pep11**, suggesting that the binding sites for the two peptides on HPV16 E6 overlap. Yet, few E6 amino acids were differentially involved which may contribute to the higher binding affinity of pep11**. Data from the HPV16 E6/pep11** interaction allowed the rational design of single amino acid exchanges in HPV18 and HPV31 E6 that enabled their binding to pep11**. Taken together, these results suggest that E6 molecular surfaces mediating E6APpep binding can also accommodate pro-apoptotic peptides that belong to different sequence families. As proof of concept, this study provides the first experimental evidence that the E6AP binding pocket is druggable, opening new possibilities for rational, structure-based drug design.
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Prescott EL, Brimacombe CL, Hartley M, Bell I, Graham S, Roberts S. Human papillomavirus type 1 E1^E4 protein is a potent inhibitor of the serine-arginine (SR) protein kinase SRPK1 and inhibits phosphorylation of host SR proteins and of the viral transcription and replication regulator E2. J Virol 2014; 88:12599-611. [PMID: 25142587 PMCID: PMC4248925 DOI: 10.1128/jvi.02029-14] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 08/13/2014] [Indexed: 01/13/2023] Open
Abstract
UNLABELLED The serine-arginine-specific protein kinase SRPK1 is a common binding partner of the E1^E4 protein of diverse human papillomavirus types. We show here for the first time that the interaction between HPV1 E1^E4 and SRPK1 leads to potent inhibition of SRPK1 phosphorylation of host serine-arginine (SR) proteins that have critical roles in mRNA metabolism, including pre-mRNA processing, mRNA export, and translation. Furthermore, we show that SRPK1 phosphorylates serine residues of SR/RS dipeptides in the hinge region of the HPV1 E2 protein in in vitro kinase assays and that HPV1 E1^E4 inhibits this phosphorylation. After mutation of the putative phosphoacceptor serine residues, the localization of the E2 protein was altered in primary human keratinocytes; with a significant increase in the cell population showing intense E2 staining of the nucleolus. A similar effect was observed following coexpression of E2 and E1^E4 that is competent for inhibition of SRPK1 activity, suggesting that the nuclear localization of E2 is sensitive to E1^E4-mediated SRPK1 inhibition. Collectively, these data suggest that E1^E4-mediated inhibition of SRPK1 could affect the functions of host SR proteins and those of the virus transcription/replication regulator E2. We speculate that the novel E4 function identified here is involved in the regulation of E2 and SR protein function in posttranscriptional processing of viral transcripts. IMPORTANCE The HPV life cycle is tightly linked to the epithelial terminal differentiation program, with the virion-producing phase restricted to differentiating cells. While the most abundant HPV protein expressed in this phase is the E4 protein, we do not fully understand the role of this protein. Few E4 interaction partners have been identified, but we had previously shown that E4 proteins from diverse papillomaviruses interact with the serine-arginine-specific protein kinase SRPK1, a kinase important in the replication cycles of a diverse range of DNA and RNA viruses. We show that HPV1 E4 is a potent inhibitor of this host cell kinase. We show that E4 inhibits SRPK1 phosphorylation, not only of cellular SR proteins involved in regulating alternative splicing of RNA but also the viral transcription/replication regulator E2. Our findings reveal a potential E4 function in regulation of viral late gene expression through the inhibition of a host cell kinase.
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He J, Ji Y, Li A, Zhang Q, Song W, Li Y, Huang H, Qian J, Zhai A, Yu X, Zhao J, Shang Q, Wei L, Zhang F. MiR-122 directly inhibits human papillomavirus E6 gene and enhances interferon signaling through blocking suppressor of cytokine signaling 1 in SiHa cells. PLoS One 2014; 9:e108410. [PMID: 25265013 PMCID: PMC4180754 DOI: 10.1371/journal.pone.0108410] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 08/22/2014] [Indexed: 11/28/2022] Open
Abstract
Human Papillomavirus (HPV) 16 infection is considered as one of the significant causes of human cervical cancer. The expression of the viral oncogenes like E6 and E7 play an important role in the development of the cancer. MiR-122 has been reported to exhibit a strong relationship with hepatitis viruses and take part in several tumor development, while the effects of miR-122 on HPV infection and the HPV viral oncogenes expression still remain unexplored. In this study, using RNAhybrid software, the potential binding sites between miR-122 and HPV16 E6 and E7 mRNAs were identified. Over and loss of miR-122 function showed that miR-122 could directly bind with HPV16 E6 mRNA and significantly inhibit its expression in SiHa cells, which was further confirmed by constructing the miR-122-E6-mu to eliminate the miR-122 binding effects with E6. The increase of the expression of type I interferon (IFN) and its classical effective molecules and the phosphorylation of signal transducers and activators of transcription (STAT1) protein indicated that miR-122 might enhance type I interferon in cervical carcinoma cells, which explained the significant reduction of HPV16 E7 and E6*I mRNA expression. This might be due to the binding between miR-122 and suppressor of cytokine signaling 1 (SOCS1) mRNA, which is the suppressor of interferon signaling pathway. Moreover, it was identified that the miR-122 binding position was nt359-nt375 in SOCS1 mRNA. Taken together, this study indicated that HPV16 could be effectively inhibited by miR-122 through both direct binding with E6 mRNA and promoting SOCS1-dependent IFN signaling pathway. Thus, miR-122 may serve as a new therapeutic option for inhibiting HPV infection.
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You X, Yang YC, Ke X, Hong SL, Hu GH. Fluorescence visualization screening for EBV-LMP1-targeted DNAzymes. Otolaryngol Head Neck Surg 2013; 150:251-8. [PMID: 24323909 DOI: 10.1177/0194599813514514] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVES To develop a novel screening method for DNAzymes targeting the LMP1 carboxy region. STUDY DESIGN To design a method to screen special DNAzymes toward the Epstein-Barr virus (EBV)-associated carcinoma before clinic use. SETTING Key Laboratory of the Ministry of Education-Molecular Biology of Infectious Diseases in Chongqing Medical University. SUBJECTS AND METHODS Four novel 10-23 DNAzymes (DZ509, DZ1037, DZ893, and DZ827) targeting the EBV-LMP1 gene were designed and evaluated by detecting enhanced green fluorescence protein (EGFP) expression of LMP1 mRNA and the protein in the nasopharyngeal carcinoma (NPC) cell line CNE2 transfected with the pEGFP-C1-LMP1c vector. The screened specific DNAzymes were then transfected into NPC cell lines C666-1 while a mutant oligonucleotide mutDZ509 and an antisense oligonucleotide ASODN509 were designed as positive and negative controls. Cell proliferation, cell apoptosis, LMP1 mRNA, and the protein were assessed using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, Annexin V-fluorescence isothiocyanate (FITC), reverse transcription polymerase chain reaction (RT-PCR), and Western blots. RESULTS The inhibition rates of fluorescence expression of the DNAzymes DZ509, DZ1037, DZ893, and DZ827 were 91.25%, 65.84%, 49.02%, and 44.56%, respectively. The results were in accordance with the inhibition effects of mRNA and protein expression. The screened DZ509 could effectively knock down endogenous LMP1 expression in C666-1 cells, inhibit cell proliferation, and induce cell apoptosis compared with mutDZ509 and ASODN509. CONCLUSION LMP1 could present a potential target for DNAzymes toward the EBV-associated carcinoma, and the EGFP expression vector could be a visible method for screening special DNAzymes before clinic use.
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Wetherill LF, Holmes KK, Verow M, Müller M, Howell G, Harris M, Fishwick C, Stonehouse N, Foster R, Blair GE, Griffin S, Macdonald A. High-risk human papillomavirus E5 oncoprotein displays channel-forming activity sensitive to small-molecule inhibitors. J Virol 2012; 86:5341-51. [PMID: 22357280 PMCID: PMC3347351 DOI: 10.1128/jvi.06243-11] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 02/15/2012] [Indexed: 01/12/2023] Open
Abstract
High-risk human papillomavirus type 16 (HPV16) is the primary causative agent of cervical cancer and therefore is responsible for significant morbidity and mortality worldwide. Cellular transformation is mediated directly by the expression of viral oncogenes, the least characterized of which, E5, subverts cellular proliferation and immune recognition processes. Despite a growing catalogue of E5-specific host interactions, little is understood regarding the molecular basis of its function. Here we describe a novel function for HPV16 E5 as an oligomeric channel-forming protein, placing it within the virus-encoded "viroporin" family. The development of a novel recombinant E5 expression system showed that E5 formed oligomeric assemblies of a defined luminal diameter and stoichiometry in membranous environments and that such channels mediated fluorescent dye release from liposomes. Hexameric E5 channel stoichiometry was suggested by native PAGE studies. In lieu of high-resolution structural information, established de novo molecular modeling and design methods permitted the development of the first specific small-molecule E5 inhibitor, capable of both abrogating channel activity in vitro and reducing E5-mediated effects on cell signaling pathways. The identification of channel activity should enhance the future understanding of the physiological function of E5 and could represent an important target for antiviral intervention.
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Eaton S, Wiktor P, Thirstrup D, Lake D, Nagaraj VJ. Efficacy of TRAIL treatment against HPV16 infected cervical cancer cells undergoing senescence following siRNA knockdown of E6/E7 genes. Biochem Biophys Res Commun 2010; 405:1-6. [PMID: 21167816 DOI: 10.1016/j.bbrc.2010.12.056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 12/10/2010] [Indexed: 11/19/2022]
Abstract
In this study we investigated E6 and E7 oncogenes from the Human Papilloma Virus as targets for siRNA knockdown in order to boost the efficacy of the anti-cancer drug 'tumor necrosis factor-related apoptosis inducing ligand' (TRAIL). SiHa cells were treated with TRAIL following transfection with E6/E7 siRNA and the expression of death receptors DR4 and DR5, cell viability, apoptosis, senescence and cell cycle analysis were undertaken using flow cytometry, MTT viability assay and cellular β-galactosidase activity assays. E6/E7 siRNA resulted in significant upregulation of death receptors DR4 and DR5 but did not result in an enhanced sensitivity to TRAIL. Our results indicate that E6/E7-siRNA induces senescence rather than apoptosis in SiHa cells. The occurrence of senescence in drug resistant cervical cancer cells such as the SiHa cell line by E6/E7 siRNA, among other factors, may prevent TRAIL induced activation of extrinsic and intrinsic pathways that lead to apoptotic cell death. Our findings are significant for combinatorial strategies for cancer therapy since the induction of senescence can preclude apoptosis rendering cells to be recalcitrant to TRAIL treatment.
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18
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Li GL, Jiang W, Xia Q, Chen SH, Ge XR, Gui SQ, Xu CJ. HPV E6 down-regulation and apoptosis induction of human cervical cancer cells by a novel lipid-soluble extract (PE) from Pinellia pedatisecta Schott in vitro. JOURNAL OF ETHNOPHARMACOLOGY 2010; 132:56-64. [PMID: 20659543 DOI: 10.1016/j.jep.2010.07.035] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2010] [Revised: 06/15/2010] [Accepted: 07/18/2010] [Indexed: 05/29/2023]
Abstract
AIM OF THE STUDY To evaluate the cytotoxicity and apoptosis induction effects of a novel lipid-soluble extract (PE) from Pinellia pedatisecta Schott on CaSki, HeLa and HBL-100 cells. Particularly, the effect of PE on HPV E6 gene expression was tested, and the mechanism of its apoptosis induction effect was also studied. MATERIALS AND METHODS Cell viability was measured by the MTT assay. DAPI staining and flow cytometric analysis (FCM) were used to identify apoptotic cells in PE-treated CaSki, HeLa, and HBL-100 cells. Expression of the HPV E6 gene in CaSki and HeLa cells was detected by real-time RT-PCR and western blot analysis. Apoptosis-associated genes were examined by RT-PCR and western blot analysis in CaSki cells. RESULTS PE inhibited the growth of CaSki and HeLa cells in a time- and dose-dependent manner, but it had no obvious inhibiting effect on HBL-100 cells except at a relatively high dose (500 μg/mL). PE could induce apoptosis in CaSki and HeLa cells in a time-dependent manner but not in HBL-100 cells. HPV E6 mRNA and protein were decreased significantly by PE. Caspase-8, caspase-3, Bax, P53 and P21 mRNAs as well as proteins were increased while Bcl-2 mRNA and protein were decreased significantly by 24 h of PE treatment. CONCLUSIONS PE can function as a tumor suppressor by inducing apoptosis in human cervical cancer cells but it has little side effect on normal cells. It probably acts via mitochondria-dependent and death receptor-dependent apoptotic pathways. HPV E6 may be the key target of its action.
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MESH Headings
- Antineoplastic Agents, Phytogenic/chemistry
- Antineoplastic Agents, Phytogenic/isolation & purification
- Antineoplastic Agents, Phytogenic/pharmacology
- Apoptosis/drug effects
- Apoptosis/genetics
- Cell Culture Techniques
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Cell Survival/drug effects
- Dose-Response Relationship, Drug
- Down-Regulation
- Drugs, Chinese Herbal/chemistry
- Drugs, Chinese Herbal/isolation & purification
- Drugs, Chinese Herbal/pharmacology
- Female
- HeLa Cells
- Humans
- Lipids/chemistry
- Microscopy, Fluorescence
- Oncogene Proteins, Viral/antagonists & inhibitors
- Oncogene Proteins, Viral/biosynthesis
- Oncogene Proteins, Viral/genetics
- Pinellia/chemistry
- Reverse Transcriptase Polymerase Chain Reaction
- Rhizome/chemistry
- Solubility
- Time Factors
- Uterine Cervical Neoplasms/metabolism
- Uterine Cervical Neoplasms/pathology
- Uterine Cervical Neoplasms/virology
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19
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Qi Z, Xu X, Zhang B, Li Y, Liu J, Chen S, Chen G, Huo X. Effect of simultaneous silencing of HPV-18 E6 and E7 on inducing apoptosis in HeLa cells. Biochem Cell Biol 2010; 88:697-704. [PMID: 20651842 DOI: 10.1139/o10-005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The objective of this investigation was to determine if simultaneous silencing of the human papillomavirus type 18 (HPV-18) E6 and E7 oncogenes using RNA interference (RNAi) would be a potential therapeutic approach against the carcinogenic activity of this virus. Two synthetic double-stranded oligonucleotides, encoding short hairpin transcripts corresponding to HPV-18 E6 and E7 genes, were cloned into pGenesilence (pGS) 1.0 vectors to produce pGS-E6, pGS-E7, and pGS-(E6+E7), respectively. Our results showed that the expression of HPV-18 E6 class 1 and HPV-18 E7 in HeLa cells was markedly decreased after being transfected with pGS-E6, pGS-E7, and pGS-(E6+E7) vectors. Of the three vectors, pGS-(E6+E7) had a greater ability to decrease the growth rate of HeLa cells, inhibit colony formation in soft agar, and significantly reduce tumor growth in nude mice. We also found that depletion of HPV-18 E6 and E7 in this manner promoted apoptosis of HeLa cells. Our data showed that simultaneously decreasing HPV-18 E6 and E7 gene expression in HeLa cells by RNAi could significantly inhibit tumor growth under in vitro conditions and in nude mice. These data suggest that gene therapy may be a possible therapeutic approach for HPV-positive cervical cancers.
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Amine A, Rivera S, Opolon P, Dekkal M, Biard DSF, Bouamar H, Louache F, McKay MJ, Bourhis J, Deutsch E, Vozenin-Brotons MC. Novel anti-metastatic action of cidofovir mediated by inhibition of E6/E7, CXCR4 and Rho/ROCK signaling in HPV tumor cells. PLoS One 2009; 4:e5018. [PMID: 19325708 PMCID: PMC2657827 DOI: 10.1371/journal.pone.0005018] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2008] [Accepted: 02/16/2009] [Indexed: 12/17/2022] Open
Abstract
Cervical cancer is frequently associated with HPV infection. The expression of E6 and E7 HPV oncoproteins is a key factor in its carcinogenicity and might also influence its virulence, including metastatic conversion. The cellular mechanisms involved in metastatic spread remain elusive, but pro-adhesive receptors and their ligands, such as SDF-1α and CXCR4 are implicated. In the present study, we assessed the possible relationship between SDF-1α/CXCR4 signaling, E6/E7 status and the metastatic process. We found that SDF-1α stimulated the invasion of E6/E7-positive cancer cell lines (HeLa and TC-1) in Matrigel though CXCR4 and subsequent Rho/ROCK activation. In pulmonary metastatic foci generated by TC-1 cells IV injection a high proportion of cells expressed membrane-associated CXCR4. In both cases models (in vitro and in vivo) cell adhesion and invasion was abrogated by CXCR4 immunological blockade supporting a contribution of SDF-1α/CXCR4 to the metastatic process. E6 and E7 silencing using stable knock-down and the approved anti-viral agent, Cidofovir decreased CXCR4 gene expression as well as both, constitutive and SDF-1α-induced cell invasion. In addition, Cidofovir inhibited lung metastasis (both adhesion and invasion) supporting contribution of E6 and E7 oncoproteins to the metastatic process. Finally, potential signals activated downstream SDF-1α/CXCR4 and involved in lung homing of E6/E7-expressing tumor cells were investigated. The contribution of the Rho/ROCK pathway was suggested by the inhibitory effect triggered by Cidofovir and further confirmed using Y-27632 (a small molecule ROCK inhibitor). These data suggest a novel and highly translatable therapeutic approach to cervix cancer, by inhibition of adhesion and invasion of circulating HPV-positive tumor cells, using Cidofovir and/or ROCK inhibition.
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Martinez I, Gardiner AS, Board KF, Monzon FA, Edwards RP, Khan SA. Human papillomavirus type 16 reduces the expression of microRNA-218 in cervical carcinoma cells. Oncogene 2008; 27:2575-82. [PMID: 17998940 PMCID: PMC2447163 DOI: 10.1038/sj.onc.1210919] [Citation(s) in RCA: 270] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 09/10/2007] [Accepted: 10/10/2007] [Indexed: 12/15/2022]
Abstract
Human papillomaviruses (HPVs) are involved in the pathogenesis of cancer of the cervix (CaCx). MicroRNA (miRNA) expression analysis using Ambion (Austin, TX, USA) arrays showed that three miRNAs were overexpressed and 24 underexpressed in cervical cell lines containing integrated HPV-16 DNA compared to the normal cervix. Furthermore, nine miRNAs were overexpressed and one underexpressed in integrated HPV-16 cell lines compared to the HPV-negative CaCx cell line C-33A. Based on microarray and/or quantitative real-time PCR and northern blot analyses, microRNA-218 (miR-218) was specifically underexpressed in HPV-positive cell lines, cervical lesions and cancer tissues containing HPV-16 DNA compared to both C-33A and the normal cervix. Expression of the E6 oncogene of high-risk HPV-16, but not that of low-risk HPV-6, reduced miR-218 expression, and conversely, RNA interference of E6/E7 oncogenes in an HPV-16-positive cell line increased miR-218 expression. We also demonstrate that the epithelial cell-specific marker LAMB3 is a target of miR-218. We also show that LAMB3 expression is increased in the presence of the HPV-16 E6 oncogene and this effect is mediated through miR-218. These findings may contribute to a better understanding of the molecular mechanisms involved in cervical carcinogenesis.
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22
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Yamayoshi A, Kato K, Suga S, Ichinoe A, Arima T, Matsuda T, Kato H, Murakami A, Wake N. Specific apoptosis induction in human papillomavirus-positive cervical carcinoma cells by photodynamic antisense regulation. Oligonucleotides 2007; 17:66-79. [PMID: 17461764 DOI: 10.1089/oli.2006.0047] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Human papillomavirus type 18 (HPV18) is frequently detected in cervical cancer cells. The viral proteins E6 and E7 are expressed consistently and have oncogenic activities. The E7 protein binds to a tumor suppressor, the retinoblastoma gene product (pRB), however, leading to the stabilization of tumor suppressor, p53 protein. On the other hand, another viral product, E6, forms complexes with p53 and abrogates its function, resulting in tumor progression. These facts imply that the E6 oncogene is one of the ideal targets for directed gene therapy in HPV-positive cervical cancer. In this study, we tried photodynamic antisense regulation of the antiapoptotic E6 expression using a photocross-linking reagent, 4,5',8-trimethylpsoralen, conjugated oligo(nucleoside phosphorothioate) (Ps-S-Oligo). This photodynamic antisense strategy effectively elicited the apoptotic death of HPV18-positive cervical cancer cells through the selective repression of E6 mRNA and consequent stabilization of p53 protein. E7-mediated signals potentially activated the p53 function and mobilized the p53 pathway to deliver pro-apoptotic signals to the cancer cells, leading to the suppression of in vivo tumorigenesis. An extremely low concentration of cisplatin in addition to Ps-S-Oligos further up-regulated p53 activity, provoking massive apoptotic induction. These results suggest that the photodynamic antisense strategy has the great therapeutic potential in HPV-positive cervical cancers.
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Sehr P, Pawlita M, Lewis J. Evaluation of different glutathione S-transferase-tagged protein captures for screening E6/E6AP interaction inhibitors using AlphaScreen. ACTA ACUST UNITED AC 2007; 12:560-7. [PMID: 17478484 DOI: 10.1177/1087057107301246] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Human papillomavirus (HPV) infection is responsible for the development of cervical cancer and its premalignant lesions in women. The virus-encoded oncogene E6 is a promising target for an anti-HPV drug therapy. The authors describe the development of a homogenous screening assay for inhibitors of the E6 interaction with its cellular target, the E6-associated protein (E6AP), based on AlphaScreen technology. The E6 protein was expressed and purified as glutathione S-transferase (GST) fusion protein, and the binding to a biotinylated E6AP peptide was monitored using GST-detecting Acceptor beads coated either with anti-GST antibody or glutathione. After optimization of the assay conditions, a commercial library of 3000 compounds was screened for inhibitors. Active compounds were retested and counterscreened for E6/E6AP specificity using biotinylated GST as a control protein. The results obtained with both types of GST-detecting reagents correlated very well and demonstrated the great potential of the newly developed glutathione-coated Acceptor beads as a detection reagent for GST fusion proteins.
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Niu XY, Peng ZL, Duan WQ, Wang H, Wang P. Inhibition of HPV 16 E6 oncogene expression by RNA interference in vitro and in vivo. Int J Gynecol Cancer 2006; 16:743-51. [PMID: 16681755 DOI: 10.1111/j.1525-1438.2006.00384.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Substantial studies have demonstrated that the initiation and progression of cervical cancer were closely associated with human papillomavirus (HPV) E6 and E7 oncogenes. The therapeutic strategy with ribozyme or antisense oligonucleotides to inhibit the expression of HPV E6 or E7 oncogenes showed effect to some degree, but problems such as low efficiency, short-period maintenance, and high cost still remain. The aim of this study was to investigate in vitro and in vivo the effect of HPV 16 E6 small interfering RNA (HPV 16 E6 siRNA) on cervical cancer cell line CaSki cells. The specific siRNA of HPV 16 E6 was synthesized and transfected into CaSki cells by liposome. The number of apoptotic cells, HPV 16 E6 messenger RNA (mRNA) level, and E6 protein expression were measured before and after the transfection by flow cytometry, reverse transcriptase-polymerase chain reaction, and Western blot, respectively. Cervical cancer in nude mice was established, and siRNA was injected directly into the nude mice peritoneal cavity or subcutaneous tumor. The efficiency of siRNA was evaluated by tumor volume change, HPV 16 E6 protein expression, and apoptosis of tumor cells. Apoptosis rate of CaSki cells at days 1, 2, 5, and 9 after siRNA transfection were 7.7%, 11.8%, 37.4%, and 12.6%, respectively. The mRNA level of HPV 16 E6 at the same time points were reduced by 77%, 83%, 59%, and 41%, respectively. But the mRNA level of beta-actin, as an internal control, showed no significant change. The inhibition rates of E6 protein synthesis at days 1, 2, 5, and 9 after the transfection were 79.7%, 80.4%, 71.3%, and 57.4%, respectively, whereas the protein levels of Lamin A/C, as internal control, had no change. In vivo, E6 siRNA administration groups showed a dramatic effect in inhibiting tumor growth, suppressing expression of E6 protein, and inducing tumor necrosis and apoptosis as compared with the control group. Direct injection of siRNA into subcutaneous tumor resulted in tumor suppression effect similar to that via the peritoneal cavity, and with additional injection better results could be achieved in cervical cancer CaSki cells. RNA interference exists, and the interference to HPV 16 E6 is specific and highly efficient both in vitro and in vivo.
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