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Gershburg E, Pagano JS. Epstein-Barr virus infections: prospects for treatment. J Antimicrob Chemother 2005; 56:277-81. [PMID: 16006448 DOI: 10.1093/jac/dki240] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Epstein-Barr virus (EBV) causes infectious mononucleosis and oral hairy leucoplakia, and is associated with a number of malignancies. There are, however, no regulatory agency-approved treatments for EBV-related diseases. Several antiviral drugs inhibit replication of EBV in cell culture including acyclic nucleoside and nucleotide analogues and pyrophosphate analogues, all of which inhibit the EBV DNA polymerase. Despite their potency in vitro, these drugs have limited use in vivo for treatment of acute primary EBV infection as well as EBV-associated malignancies for several reasons. Here we discuss novel anti-EBV compounds, including maribavir, potentially useful for the treatment of acute EBV infections. A number of experimental approaches for treatment of EBV-related malignancies that are not susceptible to conventional antiviral drug treatment are also discussed.
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Affiliation(s)
- Edward Gershburg
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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52
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Yue W, Gershburg E, Pagano JS. Hyperphosphorylation of EBNA2 by Epstein-Barr virus protein kinase suppresses transactivation of the LMP1 promoter. J Virol 2005; 79:5880-5. [PMID: 15827205 PMCID: PMC1082719 DOI: 10.1128/jvi.79.9.5880-5885.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Epstein-Barr virus (EBV) BGLF4 gene encodes a serine/threonine protein kinase (PK) that is expressed in the cytolytic cycle. EBV nuclear antigen 2 (EBNA2) is a key latency gene essential for immortalization of B lymphocytes and transactivation of viral and cellular promoters. Here we report that EBV PK phosphorylates EBNA2 at Ser-243 and that these two proteins physically associate. PK suppresses EBNA2's ability to transactivate the LMP1 promoter, and Ser-243 of EBNA2 is involved in this suppression. Moreover, EBNA2 is hyperphosphorylated during EBV reactivation in latently infected B cells, which is associated with decreased LMP1 protein levels. This is the first report about the effect of EBV PK on the function of one of its target proteins and regulation of EBNA2 phosphorylation during the EBV lytic cycle.
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Affiliation(s)
- Wei Yue
- Department of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina, Campus Box 7295, Chapel Hill, NC 27599, USA
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53
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Routier S, Peixoto P, Mérour JY, Coudert G, Dias N, Bailly C, Pierré A, Léonce S, Caignard DH. Synthesis and Biological Evaluation of Novel Naphthocarbazoles as Potential Anticancer Agents. J Med Chem 2005; 48:1401-13. [PMID: 15743184 DOI: 10.1021/jm049213f] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the efficient synthesis involving palladium-catalyzed reactions and biological evaluation of new naphthocarbazoles designed as potential anticancer agents. The use of 5- and 6-benzyloxyindoles generated three substitution sites which were successively exploited to introduce several hydrophilic side chains. The cytotoxicity of the newly designed compounds was evaluated on three cell lines. Several compounds showed a marked cytotoxicity with IC(50) values in the sub-micromolar range. This is the case for the 3-hydroxy-naphthopyrrolocarbazoledione 37, bearing a dimethylaminoethyl side chain, which is extremely cytotoxic to L1210 and DU145 cells (IC(50): 36 nM, 108 nM) and induces an accumulation of L1210 cells in the G2+M phases of the cell cycle. Some of the most cytotoxic compounds were tested for inhibition of CDK-5, GSK-3 and topoisomerase I, and their interaction with DNA was also evaluated. Interaction with DNA was detected, suggesting that nucleic acids represent a privileged target for these molecules.
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Affiliation(s)
- Sylvain Routier
- Institut de Chimie Organique et Analytique, UMR CNRS 6005, Université d'orléans, Rue de Chartres, BP 6759, 45067 Orléans Cedex 2, France.
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54
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Herget T, Freitag M, Morbitzer M, Kupfer R, Stamminger T, Marschall M. Novel chemical class of pUL97 protein kinase-specific inhibitors with strong anticytomegaloviral activity. Antimicrob Agents Chemother 2004; 48:4154-62. [PMID: 15504835 PMCID: PMC525407 DOI: 10.1128/aac.48.11.4154-4162.2004] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a major human pathogen frequently associated with life-threatening disease in immunosuppressed patients and newborns. The HCMV UL97-encoded protein kinase (pUL97) represents an important determinant of viral replication. Recent studies demonstrated that pUL97-specific kinase inhibitors are powerful tools for the control of HCMV replication. We present evidence that three related quinazoline compounds are potent inhibitors of the pUL97 kinase activity and block in vitro substrate phosphorylation, with 50% inhibitory concentrations (IC(50)s) between 30 and 170 nM. Replication of HCMV in primary human fibroblasts was suppressed with a high efficiency. The IC(50)s of these three quinazoline compounds (2.4 +/- 0.4, 3.4 +/- 0.6, and 3.9 +/- 1.1 microM, respectively) were in the range of the IC(50) of ganciclovir (1.2 +/- 0.2 microM), as determined by the HCMV green fluorescent protein-based antiviral assay. Importantly, the quinazolines were demonstrated to have strong inhibitory effects against clinical HCMV isolates, including ganciclovir- and cidofovir-resistant virus variants. Moreover, in contrast to ganciclovir, the formation of resistance to the quinazolines was not observed. The mechanisms of action of these compounds were confirmed by kinetic analyses with infected cells. Quinazolines specifically inhibited viral early-late protein synthesis but had no effects at other stages of the replication cycle, such as viral entry, consistent with a blockage of the pUL97 function. In contrast to epithelial growth factor receptor inhibitors, quinazolines affected HCMV replication even when they were added hours after virus adsorption. Thus, our findings indicate that quinazolines are highly efficient inhibitors of HCMV replication in vitro by targeting pUL97 protein kinase activity.
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Affiliation(s)
- Thomas Herget
- Institute for Clinical and Molecular Virology, University of Erlangen-Nürnberg, Erlangen 91054, Germany.
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55
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Gershburg E, Marschall M, Hong K, Pagano JS. Expression and localization of the Epstein-Barr virus-encoded protein kinase. J Virol 2004; 78:12140-6. [PMID: 15507600 PMCID: PMC525081 DOI: 10.1128/jvi.78.22.12140-12146.2004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The protein kinase (PK) encoded by the Epstein-Barr Virus (EBV) BGLF4 gene is the only EBV protein kinase. The expression pattern of EBV PK during the reactivation of the viral lytic cycle and the subcellular localization of the protein were analyzed with a polyclonal antiserum raised against a peptide corresponding to the N terminus of EBV PK. Based on previously published data (E. Gershburg and J. S. Pagano, J. Virol. 76:998-1003, 2002) and the expression pattern described here, we conclude that EBV PK is an early protein that requires viral-DNA replication for maximum expression. By biochemical fractionation, the protein could be detected mainly in the nuclear fraction 4 h after viral reactivation in Akata cells. Nuclear localization could be visualized by indirect immunofluorescence in HeLa cells transiently expressing EBV BGLF4 in the absence of other viral products. Transient expression of 3'-terminal deletion mutants of EBV BGLF4 resulted in cytoplasmic localization, confirming the presence of a nuclear localization site in the C-terminal region of the protein. In contrast to the wild-type EBV PK, all of the mutants were unable to hyperphosphorylate EA-D during coexpression or to phosphorylate ganciclovir, as measured by an in-cell activity assay. Thus, the results demonstrate that the nuclear localization, as well as the kinase activity, of BGFL4 is dependent on an intact C-terminal region.
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Affiliation(s)
- E Gershburg
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, CB no. 7295, Chapel Hill, NC 27599-7295, USA
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56
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Gershburg E, Hong K, Pagano JS. Effects of maribavir and selected indolocarbazoles on Epstein-Barr virus protein kinase BGLF4 and on viral lytic replication. Antimicrob Agents Chemother 2004; 48:1900-3. [PMID: 15105156 PMCID: PMC400567 DOI: 10.1128/aac.48.5.1900-1903.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human cytomegalovirus (HCMV) homolog of the Epstein-Barr virus (EBV) protein kinase (PK), UL97, is inhibited by maribavir (1263W94) and selected indolocarbazoles. Here we show that only one of these indolocarbazoles (K252a), but not maribavir, inhibits autophosphorylation of the EBV PK, BGLF4. However, maribavir and another indolocarbazole, NGIC-I, do inhibit EBV DNA synthesis, suggesting that although these last compounds inhibit both HCMV and EBV, they seem to operate through differ-ent pathways.
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Affiliation(s)
- Edward Gershburg
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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57
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Michel D, Mertens T. The UL97 protein kinase of human cytomegalovirus and homologues in other herpesviruses: impact on virus and host. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2004; 1697:169-80. [PMID: 15023359 DOI: 10.1016/j.bbapap.2003.11.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2003] [Accepted: 11/12/2003] [Indexed: 11/16/2022]
Abstract
The human herpesviruses, herpes simplex virus 1 (HSV-1), HSV-2, varicella zoster virus (VZV), Epstein-Barr virus (EBV), human cytomegalovirus (HCMV), human herpesvirus 6A (HHV-6A), HHV-6B, HHV-7 and HHV-8, establish persistent infections with possible recurrence during immunosuppression. HCMV replication is inhibited by the nucleoside analogue ganciclovir (GCV), the compound of choice for the treatment of HCMV diseases and preemptive treatment of infections. The viral UL97 protein (pUL97) which shares homologies with protein kinases and bacterial phosphotransferases is able to monophosphorylate GCV. Homologues of pUL97 are found in HSV (UL13), VZV (ORF47), EBV (BGLF4), HHV-6 (U69), HHV-8 (ORF36) as well as in murine CMV (M97) or rat CMV (R97). Several indolocarbazoles have been reported to be specific inhibitors of pUL97. The protein is important for efficient replication of the virus. Autophosphorylation of pUL97 was observed using different experimental systems. Most recently, it has been shown that pUL97 interacts with the DNA polymerase processivity factor pUL44. Indolocarbazole protein kinase inhibitors are promising lead compounds for the development of more specific inhibitors of HCMV.
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Affiliation(s)
- Detlef Michel
- Universitätsklinikum Ulm, Abteilung Virologie, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
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58
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Schang LM. Effects of pharmacological cyclin-dependent kinase inhibitors on viral transcription and replication. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2004; 1697:197-209. [PMID: 15023361 DOI: 10.1016/j.bbapap.2003.11.024] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2003] [Accepted: 11/12/2003] [Indexed: 10/26/2022]
Abstract
Cyclin-dependent kinases (CDKs) are required for replication of adeno-, papilloma- and other viruses that replicate only in dividing cells. Surprisingly, CDKs are also required for replication of HIV-1, HSV-1, and other viruses that can replicate in non-dividing cells. Since two low-molecular weight pharmacological CDK inhibitors (PCIs), flavopiridol (Flavo) and roscovitine (Rosco), appear to be non-toxic in human clinical trials against cancer, these drugs have been proposed as potential antiviral drugs. Rosco preferentially inhibits CDKs involved in cell cycle regulation (CDK1, 2, and 7) or neuronal functions (CDK5), whereas Flavo preferentially inhibits CDKs involved in cell cycle (CDK1, 2, 4, 7) or transcription (CDK7, and 9). As potential antivirals, PCIs display several advantages: (i) they are active against many different viruses, including drug-resistant strains of HIV-1 and HSV-1; (ii) PCI-resistant mutants of HIV-1 or HSV-1 have not been identified; and (iii) the antiviral effects of PCIs and conventional antivirals appear to be additive (as expected from drugs that target independent pathways). Moreover, PCIs target both the etiological agents (i.e., the virus) and the pathogenic mechanisms (i.e., unrestricted cell division) of the many diseases that include both a CDK-requiring virus and unrestricted cell division (e.g., Kaposi's sarcoma, cervical carcinoma, HIV-associated nephropathy-HIVAN). This is nicely illustrated in a recent study which demonstrated the efficacy of Flavo in a mouse model of HIVAN. Herein, we will review the involvement of CDKs in viral replication and the antiviral properties of the most extensively characterized PCIs, with special emphasis on the mechanisms of inhibition of viral transcription.
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Affiliation(s)
- Luis M Schang
- Department of Biochemistry and Department of Medical Microbiology and Immunology, Signal Transduction Research Group, Molecular Mechanisms of Growth Control Research Group, University of Alberta, Canada.
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59
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Eickhoff J, Hanke M, Stein-Gerlach M, Kiang TP, Herzberger K, Habenberger P, Müller S, Klebl B, Marschall M, Stamminger T, Cotten M. RICK Activates a NF-κB-dependent Anti-human Cytomegalovirus Response. J Biol Chem 2004; 279:9642-52. [PMID: 14670961 DOI: 10.1074/jbc.m312893200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The adapter kinase receptor interacting protein-like interacting caspase-like apoptosis regulatory protein kinase (RICK, also called RIP2 and CARDIAK) was found to be elevated at both the protein and RNA levels during human cytomegalovirus (HCMV) replication, suggesting either that the virus may require RICK for replication or that RICK is part of an unsuccessful host attempt to inhibit HCMV replication. It is demonstrated here that forced expression of RICK in either a kinase active or inactive form activates nuclear factor (NF)-kappaB by means of its intermediate domain and potently blocks HCMV replication in human fibroblasts. Importantly, NF-kappaB activation, which exerted a modestly positive effect on the early phase of infection, clearly had a strongly negative impact during later viral steps. A stable inhibitor of NF-kappaB (IkappaB) reverses the RICK inhibitory effect, and activation of NF-kappaB by IkappaB kinase beta expression is inhibitory to HCMV, demonstrating that NF-kappaB activation is part of a potent anti-HCMV response. Supernatant transfer experiments identified interferon-beta as a downstream component of the RICK inhibitory pathway. RICK expression was found to synergize with HCMV infection in the induction of interferon-beta expression. This study identifies an endogenous RICK-activated, NF-kappaB- and interferon-beta-dependent antiviral pathway that is either inhibited or faulty under normal HCMV replication conditions; efforts to bolster this pathway may lead to novel anti-viral approaches.
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Affiliation(s)
- Jan Eickhoff
- Axxima Pharmaceuticals AG, 81377 München, Germany
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60
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Cioc AM, Allen C, Kalmar JR, Suster S, Baiocchi R, Nuovo GJ. Oral plasmablastic lymphomas in AIDS patients are associated with human herpesvirus 8. Am J Surg Pathol 2004; 28:41-6. [PMID: 14707862 DOI: 10.1097/00000478-200401000-00003] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Human herpes virus type 8 (HHV8) has been strongly associated with Kaposi sarcoma, primary effusion lymphoma (PEL), and Castleman's disease. To our knowledge, infection by this virus has not been strongly associated with other hematopathologic malignancies. We examined five oral cavity lymphomas from men with AIDS for HHV8 and HIV-1 by reverse transcriptase in situ polymerase chain reaction, as well as for Epstein-Barr virus (EBV) (EBER-1, -2) using in situ hybridization and HHV8 protein with immunohistochemistry. Four of these tumors were plasmablastic lymphomas; the final case was diffuse large B-cell lymphoma. Most of the neoplastic cells in these five lymphomas contained HHV8 RNA and protein. Further, the four plasmablastic lymphoma cases had tumor cells that contained EBV. HIV-1 RNA was not detected in the tumor cells but was noted in surrounding benign T cells. In comparison, HHV8 RNA was not detected in any of the five oral cavity lymphomas from people who did not have acquired immunosuppression nor in five lymphomas from AIDS patients that were located at a site other than the oral cavity. It is concluded that oral cavity lymphomas from people with AIDS are strongly associated with infection by HHV8 and EBV. Given the poor prognosis of oral cavity lymphomas in immunocompromised patients, therapy directed against the HHV8 and EBV infection may be of therapeutic value.
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Affiliation(s)
- Adina M Cioc
- Department of Pathology, Ohio State University Medical Center and College of Dentistry, Columbus, OH 43210, USA
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61
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Marschall M, Freitag M, Suchy P, Romaker D, Kupfer R, Hanke M, Stamminger T. The protein kinase pUL97 of human cytomegalovirus interacts with and phosphorylates the DNA polymerase processivity factor pUL44. Virology 2003; 311:60-71. [PMID: 12832203 DOI: 10.1016/s0042-6822(03)00147-8] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The protein kinase pUL97 of human cytomegalovirus plays important but incompletely defined roles in viral replication. Concerning the early phase of infection, it is postulated that pUL97 possesses regulatory functions in gene expression and/or DNA synthesis. Here we report that pUL97 interacts with an essential component of the replication complex, the DNA polymerase processivity factor pUL44. Interaction was determined by yeast two-hybrid and coimmunoprecipitation analyses and was mapped to the pUL97 region 366-459. In vitro kinase assays demonstrated that pUL44, coimmunoprecipitated either from transfected or from infected cells, is phosphorylated by pUL97 (but not by a catalytically inactive pUL97-mutant). In infected fibroblasts, immunofluorescence analysis revealed that pUL97 and pUL44 accumulate in the nucleus and are both incorporated into viral replication centers. The treatment with inhibitors of DNA synthesis or pUL97 kinase activity largely prevented colocalization. Thus, pUL97 may be indirectly involved in viral genome replication by modifying the replication cofactor pUL44.
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Affiliation(s)
- Manfred Marschall
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nümberg, Martinsried, Germany.
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62
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Coen DM, Schaffer PA. Antiherpesvirus drugs: a promising spectrum of new drugs and drug targets. Nat Rev Drug Discov 2003; 2:278-88. [PMID: 12669027 DOI: 10.1038/nrd1065] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the absence of effective vaccines to control herpesvirus infections, nucleosidic antiviral drugs have been the mainstay of clinical treatment since their development in the late 1970s. However, given the drawbacks of these drugs, including the increasing emergence of drug-resistant clinical isolates, new strategies for treating herpesvirus infections are warranted. A range of promising new drugs with novel molecular targets has been developed, but will they cure latent infections?
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Affiliation(s)
- Donald M Coen
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachussets 02115, USA.
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