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Rab R, Ehrhardt A, Achyut BR, Joshi D, Gilbert‐Ross M, Huang C, Floyd K, Borovjagin AV, Parker WB, Sorscher EJ, Hong JS. Evaluating antitumor activity of Escherichia coli purine nucleoside phosphorylase against head and neck patient-derived xenografts. Cancer Rep (Hoboken) 2023; 6:e1708. [PMID: 36253876 PMCID: PMC9939994 DOI: 10.1002/cnr2.1708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 08/01/2022] [Accepted: 08/10/2022] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Purine nucleoside phosphorylase (PNP) gene transfer represents a promising approach to treatment of head and neck malignancies. We tested recombinant adenovirus already in phase I/II clinical testing and leading-edge patient-derived xenografts (PDX) as a means to optimize this therapeutic strategy. METHODS Our experiments investigated purine base cytotoxicity, PNP enzyme activity following treatment of malignant tissue, tumor mass regression, viral receptor studies, and transduction by tropism-modified adenovirus. RESULTS Replication deficient vector efficiently transduced PDX cells and mediated significant anticancer effect following treatment with fludarabine phosphate in vivo. Either 6-methylpurine or 2-fluoroadenine (toxic molecules generated by the PNP approach) ablated head and neck cancer cell proliferation. High levels of adenovirus-3 specific receptors were detected in human tumor models, and vector was evaluated that utilizes this pathway. CONCLUSIONS Our studies provide the scientific foundation necessary to improve PNP prodrug cleavage and advance a new treatment for head and neck cancer.
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Affiliation(s)
- Regina Rab
- Department of Pediatrics and Children's Hospital of AtlantaEmory University School of MedicineAtlantaGeorgiaUSA
| | - Annette Ehrhardt
- Department of Pediatrics and Children's Hospital of AtlantaEmory University School of MedicineAtlantaGeorgiaUSA
| | - Bhagelu R. Achyut
- Winship Cancer InstituteEmory University School of MedicineAtlantaGeorgiaUSA
| | - Disha Joshi
- Department of Pediatrics and Children's Hospital of AtlantaEmory University School of MedicineAtlantaGeorgiaUSA
| | | | - Chunzi Huang
- Winship Cancer InstituteEmory University School of MedicineAtlantaGeorgiaUSA
| | - Katharine Floyd
- Winship Cancer InstituteEmory University School of MedicineAtlantaGeorgiaUSA
| | - Anton V. Borovjagin
- Department of Biomedical EngineeringUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - William B. Parker
- Department of PharmacologyUniversity of Alabama at Birmingham; PNP Therapeutics, Inc.BirminghamAlabamaUSA
| | - Eric J. Sorscher
- Department of Pediatrics and Children's Hospital of AtlantaEmory University School of MedicineAtlantaGeorgiaUSA
- Winship Cancer InstituteEmory University School of MedicineAtlantaGeorgiaUSA
| | - Jeong S. Hong
- Department of Pediatrics and Children's Hospital of AtlantaEmory University School of MedicineAtlantaGeorgiaUSA
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2
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Xu L, Wang Y, Ji Y, Li P, Cao W, Wu S, Kennelly E, Long C. Nutraceutical Study on Maianthemum atropurpureum, a Wild Medicinal Food Plant in Northwest Yunnan, China. Front Pharmacol 2021; 12:710487. [PMID: 34393791 PMCID: PMC8363226 DOI: 10.3389/fphar.2021.710487] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 07/20/2021] [Indexed: 11/13/2022] Open
Abstract
Maianthemum atropurpureum (Franch) LaFrankie (Asparagaceae), called nibai in Tibetan or dongka in Drung or zhu-ye-cai in local Chinese, is a wild vegetable consumed by the Tibetan people and other ethnic groups in Northwest Yunnan, China. It is also a traditional medicinal plant used by different linguistic groups for antimicrobial purposes. However the nutritional and phytochemical compositions of this important medicinal food plant have not been well studied previously. In this study, the nutrient content for nibai was determined by the China National Standards (GB) methods, and the phytochemical analysis involved multiple chromatographic and spectral methods including LC-TOF-MS analysis. Dried nibai is a rich source of protein (ca. 24.6%), with 18 of the 21 common amino acids. The amino acid content of nibai can reach up to 17.9/100 g, with the essential amino acids as major contributors, corresponding to 42.3% of the total amino acids. Nibai contains rich mineral elements, dietary fiber, vitamins, β-carotene, carbohydrates, and lipids. The phytochemical content of nibai was examined by conventional isolation strategies, as well as HR-ESI-TOF-MS to detect and identify 16 compounds including nine steroid saponins and seven flavonoids. Among these compounds, uridine, adenosine, guanosine, and β-methyl-6-methyl-d-glucopyranoside were found from the genus Maianthemum for the first time. These results help to demonstrate that the local people's practice of consuming Maianthemum atropurpureum is reasonable due to its high levels of vitamins, minerals, essential amino-acids, and phytochemicals. Nibai may be further developed in Tibet and surrounding regions, and beyond as a health food, nutraceutical, and/or dietary supplement product.
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Affiliation(s)
- Li Xu
- Key Laboratory of Ecology and Environment in Minority Areas, National Ethnic Affairs Commission, Minzu University of China, Beijing, China.,College of Life and Environmental Sciences, Minzu University of China, Beijing, China
| | - Yizhou Wang
- Key Laboratory of Ecology and Environment in Minority Areas, National Ethnic Affairs Commission, Minzu University of China, Beijing, China.,College of Life and Environmental Sciences, Minzu University of China, Beijing, China
| | - Yuanyuan Ji
- Key Laboratory of Ecology and Environment in Minority Areas, National Ethnic Affairs Commission, Minzu University of China, Beijing, China.,College of Life and Environmental Sciences, Minzu University of China, Beijing, China.,Key Laboratory of Ethnomedicine, Ministry of Education, Minzu University of China, Beijing, China.,Department of Biological Sciences, Lehman College City University of New York, New York, NY, United States
| | - Ping Li
- Key Laboratory of Ecology and Environment in Minority Areas, National Ethnic Affairs Commission, Minzu University of China, Beijing, China.,College of Life and Environmental Sciences, Minzu University of China, Beijing, China
| | - Wujisiguleng Cao
- Key Laboratory of Ecology and Environment in Minority Areas, National Ethnic Affairs Commission, Minzu University of China, Beijing, China.,College of Life and Environmental Sciences, Minzu University of China, Beijing, China.,Key Laboratory of Ethnomedicine, Ministry of Education, Minzu University of China, Beijing, China
| | - Shibiao Wu
- Department of Biological Sciences, Lehman College City University of New York, New York, NY, United States
| | - Edward Kennelly
- Department of Biological Sciences, Lehman College City University of New York, New York, NY, United States.,Ph.D. Programs in Biochemistry, Biology, and Chemistry, The Graduate Center, City University of New York, New York, NY, United States
| | - Chunlin Long
- Key Laboratory of Ecology and Environment in Minority Areas, National Ethnic Affairs Commission, Minzu University of China, Beijing, China.,College of Life and Environmental Sciences, Minzu University of China, Beijing, China.,Key Laboratory of Ethnomedicine, Ministry of Education, Minzu University of China, Beijing, China
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3
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Against the Resilience of High-Grade Gliomas: Gene Therapies (Part II). Brain Sci 2021; 11:brainsci11080976. [PMID: 34439595 PMCID: PMC8393930 DOI: 10.3390/brainsci11080976] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 07/12/2021] [Accepted: 07/19/2021] [Indexed: 12/29/2022] Open
Abstract
Introduction: High-grade gliomas (HGGs) still have a high rate of recurrence and lethality. Gene therapies were projected to overcome the therapeutic resilience of HGGs, due to the intrinsic genetic heterogenicity and immune evasion pathways. The present literature review strives to provide an updated overview of the novel gene therapies for HGGs treatment, highlighting evidence from clinical trials, molecular mechanisms, and future perspectives. Methods: An extensive literature review was conducted through PubMed/Medline and ClinicalTrials.gov databases, using the keywords “high-grade glioma,” “glioblastoma,” and “malignant brain tumor”, combined with “gene therapy,” “oncolytic viruses,” “suicide gene therapies,” “tumor suppressor genes,” “immunomodulatory genes,” and “gene target therapies”. Only articles in English and published in the last 15 years were chosen, further screened based on best relevance. Data were analyzed and described according to the PRISMA guidelines. Results: Viruses were the most vehicles employed for their feasibility and transduction efficiency. Apart from liposomes, other viral vehicles remain largely still experimental. Oncolytic viruses and suicide gene therapies proved great results in phase I, II preclinical, and clinical trials. Tumor suppressor, immunomodulatory, and target genes were widely tested, showing encouraging results especially for recurrent HGGs. Conclusions: Oncolytic virotherapy and suicide genes strategies are valuable second-line treatment options for relapsing HGGs. Immunomodulatory approaches, tumor suppressor, and target genes therapies may implement and upgrade standard chemoradiotherapy. Future research aims to improve safety profile and prolonging therapeutic effectiveness. Further clinical trials are needed to assess the efficacy of gene-based therapies.
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4
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Su M, Zhang Z, Zhou L, Han C, Huang C, Nice EC. Proteomics, Personalized Medicine and Cancer. Cancers (Basel) 2021; 13:2512. [PMID: 34063807 PMCID: PMC8196570 DOI: 10.3390/cancers13112512] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 05/12/2021] [Accepted: 05/17/2021] [Indexed: 02/05/2023] Open
Abstract
As of 2020 the human genome and proteome are both at >90% completion based on high stringency analyses. This has been largely achieved by major technological advances over the last 20 years and has enlarged our understanding of human health and disease, including cancer, and is supporting the current trend towards personalized/precision medicine. This is due to improved screening, novel therapeutic approaches and an increased understanding of underlying cancer biology. However, cancer is a complex, heterogeneous disease modulated by genetic, molecular, cellular, tissue, population, environmental and socioeconomic factors, which evolve with time. In spite of recent advances in treatment that have resulted in improved patient outcomes, prognosis is still poor for many patients with certain cancers (e.g., mesothelioma, pancreatic and brain cancer) with a high death rate associated with late diagnosis. In this review we overview key hallmarks of cancer (e.g., autophagy, the role of redox signaling), current unmet clinical needs, the requirement for sensitive and specific biomarkers for early detection, surveillance, prognosis and drug monitoring, the role of the microbiome and the goals of personalized/precision medicine, discussing how emerging omics technologies can further inform on these areas. Exemplars from recent onco-proteogenomic-related publications will be given. Finally, we will address future perspectives, not only from the standpoint of perceived advances in treatment, but also from the hurdles that have to be overcome.
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Affiliation(s)
- Miao Su
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China; (M.S.); (Z.Z.); (L.Z.); (C.H.)
| | - Zhe Zhang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China; (M.S.); (Z.Z.); (L.Z.); (C.H.)
| | - Li Zhou
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China; (M.S.); (Z.Z.); (L.Z.); (C.H.)
| | - Chao Han
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China; (M.S.); (Z.Z.); (L.Z.); (C.H.)
| | - Canhua Huang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China; (M.S.); (Z.Z.); (L.Z.); (C.H.)
| | - Edouard C. Nice
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
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5
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Hassan AEA, Abou-Elkhair RAI, Maaroof HM, Secrist JA. Synthesis of 9-(6-Deoxy-α-L-Talofuranosyl)-6-Methylpurine and 9-(6-Deoxy-β-D-Allofuranosyl)-6-Methylpurine Nucleosides. ACTA ACUST UNITED AC 2020; 81:e105. [PMID: 32255553 DOI: 10.1002/cpnc.105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
6-Methylpurine (MeP) is a cytotoxic adenine analog that does not exhibit selectivity when administered systemically and could be very useful in a gene therapy approach to cancer treatment involving Escherichia coli purine nucleoside phosphorylase (PNP). 9-(6-Deoxy-β-D-allofuranosyl)-6-methylpurine [methyl(allo)-MePR, 18] and 9-(6-deoxy-α-L-talofuranosyl)-6-methylpurine [methyl(talo)-MePR, 21] were synthesized as potential prodrugs for MeP in the E. coli PNP/prodrug cancer gene therapy approach. The detailed syntheses of [methyl(allo)-MePR] and [methyl(talo)-MePR] are described. The glycosyl donors, 1,2-di-O-acetyl-3,5-di-O-benzyl-α-D-allofuranose (12) and 1-O-acetyl-3-O-benzyl-2,5-di-O-benzoyl-α-L-talofuranose (16) were prepared from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (4) in nine and eleven steps, respectively. Vorbrüggen coupling of the latter glycosyl donors with 6-methylpurine (3), followed by deprotection of the sugar hydroxyl groups, gave the title compounds in good overall yields. © 2020 by John Wiley & Sons, Inc. Basic Protocol 1: Preparation of 6-methylpurine Basic Protocol 2: Preparation of the D-allofuranose derivative (12) Basic Protocol 3: Preparation of 6-deoxy-α-L-talofuranoside Basic Protocol 4: Preparation of methyl(allo)-MePR (18) Basic Protocol 5: Preparation of methyl(talo)-MePR (21).
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Affiliation(s)
- Abdalla E A Hassan
- Southern Research Institute, Birmingham, Alabama.,Applied Nucleic Acids Research Center, Zagazig University, Egypt
| | | | - Hend M Maaroof
- Applied Nucleic Acids Research Center, Zagazig University, Egypt
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The use of Trichomonas vaginalis purine nucleoside phosphorylase to activate fludarabine in the treatment of solid tumors. Cancer Chemother Pharmacol 2020; 85:573-583. [PMID: 31915968 DOI: 10.1007/s00280-019-04018-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 12/17/2019] [Indexed: 10/25/2022]
Abstract
Treatment with fludarabine phosphate (9-β-D-arabinofuranosyl-2-F-adenine 5'-phosphate, F-araAMP) leads to regressions and cures of human tumor xenografts that express Escherichia coli purine nucleoside phosphorylase (EcPNP). This occurs despite the fact that fludarabine (F-araA) is a relatively poor substrate for EcPNP, and is cleaved to liberate 2-fluoroadenine at a rate only 0.3% that of the natural E. coli PNP substrate, adenosine. In this study, we investigated a panel of naturally occurring PNPs to identify more efficient enzymes that may be suitable for metabolizing F-araA as part of experimental cancer therapy. We show that Trichomonas vaginalis PNP (TvPNP) cleaves F-araA with a catalytic efficiency 25-fold greater than the prototypic E. coli enzyme. Cellular extracts from human glioma cells (D54) transduced with lentivirus stably expressing TvPNP (D54/TvPNP) were found to cleave F-araA at a rate similar to extracts from D54 cells expressing EcPNP, although much less enzyme was expressed per cell in the TvPNP transduced condition. As a test of safety and efficacy using TvPNP, human head and neck squamous cell carcinoma (FaDu) xenografts expressing TvPNP were studied in nude mice and shown to exhibit robust tumor regressions, albeit with partial weight loss that resolved post-therapy. F-araAMP was also a very effective treatment for mice bearing D54/TvPNP xenografts in which approximately 10% of tumor cells expressed the enzyme, indicating pronounced ability to kill non-transduced tumor cells (high bystander activity). Moreover, F-araAMP demonstrated activity against D54 tumors injected with an E1, E3 deleted adenoviral vector encoding TvPNP. In that setting, despite higher F-araA cleavage activity using TvPNP, tumor responses were similar to those obtained with EcPNP, indicating factors other than F-Ade production may limit regressions of the D54 murine xenograft model. Our results establish that TvPNP is a favorable enzyme for activating F-araA, and support further studies in combination with F-araAMP for difficult-to-treat human cancers.
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7
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Camici M, Garcia-Gil M, Pesi R, Allegrini S, Tozzi MG. Purine-Metabolising Enzymes and Apoptosis in Cancer. Cancers (Basel) 2019; 11:cancers11091354. [PMID: 31547393 PMCID: PMC6769685 DOI: 10.3390/cancers11091354] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/03/2019] [Accepted: 09/07/2019] [Indexed: 12/17/2022] Open
Abstract
The enzymes of both de novo and salvage pathways for purine nucleotide synthesis are regulated to meet the demand of nucleic acid precursors during proliferation. Among them, the salvage pathway enzymes seem to play the key role in replenishing the purine pool in dividing and tumour cells that require a greater amount of nucleotides. An imbalance in the purine pools is fundamental not only for preventing cell proliferation, but also, in many cases, to promote apoptosis. It is known that tumour cells harbour several mutations that might lead to defective apoptosis-inducing pathways, and this is probably at the basis of the initial expansion of the population of neoplastic cells. Therefore, knowledge of the molecular mechanisms that lead to apoptosis of tumoural cells is key to predicting the possible success of a drug treatment and planning more effective and focused therapies. In this review, we describe how the modulation of enzymes involved in purine metabolism in tumour cells may affect the apoptotic programme. The enzymes discussed are: ectosolic and cytosolic 5'-nucleotidases, purine nucleoside phosphorylase, adenosine deaminase, hypoxanthine-guanine phosphoribosyltransferase, and inosine-5'-monophosphate dehydrogenase, as well as recently described enzymes particularly expressed in tumour cells, such as deoxynucleoside triphosphate triphosphohydrolase and 7,8-dihydro-8-oxoguanine triphosphatase.
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Affiliation(s)
- Marcella Camici
- Dipartimento di Biologia, Unità di Biochimica, Via S. Zeno 51, 56127 Pisa, Italy.
| | - Mercedes Garcia-Gil
- Dipartimento di Biologia, Unità di Fisiologia Generale, Via S. Zeno 31, 56127 Pisa, Italy
| | - Rossana Pesi
- Dipartimento di Biologia, Unità di Biochimica, Via S. Zeno 51, 56127 Pisa, Italy
| | - Simone Allegrini
- Dipartimento di Biologia, Unità di Biochimica, Via S. Zeno 51, 56127 Pisa, Italy
| | - Maria Grazia Tozzi
- Dipartimento di Biologia, Unità di Biochimica, Via S. Zeno 51, 56127 Pisa, Italy
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Abstract
"Tumor chemosensitivity" can be achieved by the expression of the herpes simplex virus thymidine kinase gene in cells, followed by the conversion of the "prodrug" ganciclovir into the therapeutic drug inside the cells. This system presaged other combinations of suicide genes and prodrugs, including cytosine deaminase/5-fluorocytosine, purine nucleoside phosphorylase/6-methylpurine deoxyriboside, and horseradish peroxidase/indole-3-acetic acid.
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Affiliation(s)
- Nejat Düzgüneş
- Department of Biomedical Sciences, Arthur A. Dugoni School of Dentistry, University of the Pacific, San Francisco, CA, USA.
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9
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Sinitsyna EV, Timofeev VI, Zhukhlistova NE, Muravieva TI, Kostromina MA, Esipov RS, Kuranova IP. Crystallization and Preliminary X-ray Diffraction Study of Purine Nucleoside Phosphorylase from the Thermophilic Bacterium Thermus thermophilus Strain HB27. CRYSTALLOGR REP+ 2018. [DOI: 10.1134/s1063774518050279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Fiedler JD, Fishman MR, Brown SD, Lau J, Finn MG. Multifunctional Enzyme Packaging and Catalysis in the Qβ Protein Nanoparticle. Biomacromolecules 2018; 19:3945-3957. [DOI: 10.1021/acs.biomac.8b00885] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jason D. Fiedler
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Maxwell R. Fishman
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Steven D. Brown
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Jolene Lau
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - M. G. Finn
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
- School of Chemistry and Biochemistry, School of Biological Sciences, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332, United States
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Parker WB, Sorscher EJ. Use of E. coli Purine Nucleoside Phosphorylase in the Treatment of Solid Tumors. Curr Pharm Des 2017; 23:CPD-EPUB-86774. [PMID: 29119917 PMCID: PMC6224313 DOI: 10.2174/1381612823666171109101851] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND The selective expression of non-human genes in tumor tissue to activate non-toxic compounds (Gene Directed Prodrug Enzyme Therapy, GDEPT) is a novel strategy designed for killing tumor cells in patients with little or no systemic toxicity. Numerous non-human genes have been evaluated, but none have yet been successful in the clinic. METHODS Unlike human purine nucleoside phosphorylase (PNP), E. coli PNP accepts adenine containing nucleosides as substrates, and is therefore able to selectively activate non-toxic purine analogs in tumor tissue. Various in vitro and in vivo assays have been utilized to evaluate E. coli PNP as a potential activating enzyme. RESULTS We and others have demonstrated excellent in vitro and in vivo anti-tumor activity with various GDEPT strategies utilizing E. coli PNP to activate purine nucleoside analogs. A phase I clinical trial utilizing recombinant adenoviral vector for delivery of E. coli PNP to solid tumors followed by systemic administration of fludarabine phosphate (NCT01310179; IND# 14271) has recently been completed. In this trial, significant anti-tumor activity was demonstrated with negligible toxicity related to the therapy. The mechanism of cell kill (inhibition of RNA and protein synthesis) is distinct from all currently used anticancer drugs and all experimental compounds under development. The approach has demonstrated excellent ability to kill neighboring tumor cells that do not express E. coli PNP, is active against non-proliferating and proliferating tumors cells (as well as tumor stem cells, stroma), and is therefore very effective against solid tumors with a low growth fraction. CONCLUSION The unique attributes distinguish this approach from other GDEPT strategies and are precisely those required to mediate significant improvements in antitumor therapy.
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Hassan AEA, Abou-Elkhair RAI, Parker WB, Allan PW, Secrist JA. 6-Methylpurine derived sugar modified nucleosides: Synthesis and evaluation of their substrate activity with purine nucleoside phosphorylases. Bioorg Chem 2015; 65:9-16. [PMID: 26745284 DOI: 10.1016/j.bioorg.2015.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 12/22/2015] [Accepted: 12/23/2015] [Indexed: 01/10/2023]
Abstract
6-Methylpurine (MeP) is cytotoxic adenine analog that does not exhibit selectivity when administered systemically, and could be very useful in a gene therapy approach to cancer treatment involving Escherichia coli PNP. The prototype MeP releasing prodrug, 9-(β-d-ribofuranosyl)-6-methylpurine, MeP-dR has demonstrated good activity against tumors expressing E. coli PNP, but its antitumor activity is limited due to toxicity resulting from the generation of MeP from gut bacteria. Therefore, we have embarked on a medicinal chemistry program to identify non-toxic MeP prodrugs that could be used in conjunction with E. coli PNP. In this work, we report on the synthesis of 9-(6-deoxy-β-d-allofuranosyl)-6-methylpurine (3) and 9-(6-deoxy-5-C-methyl-β-d-ribo-hexofuranosyl)-6-methylpurine (4), and the evaluation of their substrate activity with several phosphorylases. The glycosyl donors; 1,2-di-O-acetyl-3,5-di-O-benzyl-α-d-allofuranose (10) and 1-O-acetyl-3-O-benzyl-2,5-di-O-benzoyl-6-deoxy-5-C-methyl-β-d-ribohexofuran-ose (15) were prepared from 1,2:5,6-di-O-isopropylidine-α-d-glucofuranose in 9 and 11 steps, respectively. Coupling of 10 and 15 with silylated 6-methylpurine under Vorbrüggen glycosylation conditions followed conventional deprotection of the hydroxyl groups furnished 5'-C-methylated-6-methylpurine nucleosides 3 and 4, respectively. Unlike 9-(6-deoxy-α-l-talo-furanosyl)-6-methylpurine, which showed good substrate activity with E. coli PNP mutant (M64V), the β-d-allo-furanosyl derivative 3 and the 5'-di-C-methyl derivative 4 were poor substrates for all tested glycosidic bond cleavage enzymes.
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Affiliation(s)
- Abdalla E A Hassan
- Southern Research Institute, P.O. Box 55305, Birmingham, AL 35255-5305, USA; Applied Nucleic Acids Research Center, Zagazig University, Egypt.
| | | | - William B Parker
- Southern Research Institute, P.O. Box 55305, Birmingham, AL 35255-5305, USA; PNP Therapeutics Inc., 15 Richard Arrington Jr. Blvd North, Birmingham, AL 35203, USA
| | - Paula W Allan
- Southern Research Institute, P.O. Box 55305, Birmingham, AL 35255-5305, USA
| | - John A Secrist
- Southern Research Institute, P.O. Box 55305, Birmingham, AL 35255-5305, USA
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13
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Hassan AEA, Abou-Elkhair RAI, Parker WB, Allan PW, Secrist JA. 6-Methylpurine derived sugar modified nucleosides: Synthesis and in vivo antitumor activity in D54 tumor expressing M64V-Escherichia coli purine nucleoside phosphorylase. Eur J Med Chem 2015; 108:616-622. [PMID: 26724729 DOI: 10.1016/j.ejmech.2015.12.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Revised: 11/24/2015] [Accepted: 12/14/2015] [Indexed: 10/22/2022]
Abstract
Impressive antitumor activity has been observed with fludarabine phosphate against tumors that express Escherichia coli purine nucleoside phosphorylase (PNP) due to the liberation of 2-fluoroadenine in the tumor tissue. 6-Methylpurine (MeP) is another cytotoxic adenine analog that does not exhibit selectivity when administered systemically, and could be very useful in a gene therapy approach to cancer treatment involving E. coli PNP. The prototype MeP releasing prodrug 9-(2-deoxy-β-d-ribofuranosyl)-6-methylpurine (1) [MeP-dR] has demonstrated good activity against tumors expressing E. coli PNP, but its antitumor activity is limited due to toxicity resulting from the generation of MeP from gut bacteria. Therefore, we have embarked on a medicinal chemistry program to identify a combination of non-toxic MeP prodrugs and non-human adenosine glycosidic bond cleaving enzymes. The two best MeP-based substrates with M64V-E coli PNP, a mutant which was engineered to tolerate modification at the 5'-position of adenosine and its analogs, were 9-(6-deoxy-α-l-talofuranosyl)-6-methylpurine (3) [methyl(talo)-MeP-R] and 9-(α-l-lyxofuranosyl)6-methylpurine (4) [lyxo-MeP-R]. The detailed synthesis methyl(talo)-MeP-R and lyxo-MeP-R, and the evaluation of their substrate activity with 4 enzymes not normally associated with cancer patients is described. In addition, we have determined the intraperitoneal pharmacokinetic (ip-PK) properties of methyl(talo)-MeP-R and have determined its in vivo bystander activity in mice bearing D54 tumors that express M64V PNP. The observed good in vivo bystander activity of [methyl(talo)-MeP-R/M64V-E coli PNP combination suggests that these agents could be useful for the treatment of cancer.
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Affiliation(s)
- Abdalla E A Hassan
- Southern Research Institute, P.O. Box 55305, Birmingham, AL, 35255-5305, USA; Applied Nucleic Acids Research Centre, Zagazig University, Zagazig, PO Box 44519, Egypt.
| | - Reham A I Abou-Elkhair
- Southern Research Institute, P.O. Box 55305, Birmingham, AL, 35255-5305, USA; Applied Nucleic Acids Research Centre, Zagazig University, Zagazig, PO Box 44519, Egypt
| | - William B Parker
- Southern Research Institute, P.O. Box 55305, Birmingham, AL, 35255-5305, USA; PNP Therapeutics Inc., 15 Richard Arrington Jr. Blvd North, Birmingham, AL, 35203, USA
| | - Paula W Allan
- Southern Research Institute, P.O. Box 55305, Birmingham, AL, 35255-5305, USA
| | - John A Secrist
- Southern Research Institute, P.O. Box 55305, Birmingham, AL, 35255-5305, USA
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Lehouritis P, Stanton M, McCarthy FO, Jeavons M, Tangney M. Activation of multiple chemotherapeutic prodrugs by the natural enzymolome of tumour-localised probiotic bacteria. J Control Release 2015; 222:9-17. [PMID: 26655063 DOI: 10.1016/j.jconrel.2015.11.030] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/26/2015] [Accepted: 11/27/2015] [Indexed: 12/15/2022]
Abstract
Some chemotherapeutic drugs (prodrugs) require activation by an enzyme for efficacy. We and others have demonstrated the ability of probiotic bacteria to grow specifically within solid tumours following systemic administration, and we hypothesised that the natural enzymatic activity of these tumour-localised bacteria may be suitable for activation of certain such chemotherapeutic drugs. Several wild-type probiotic bacteria; Escherichia coli Nissle, Bifidobacterium breve, Lactococcus lactis and Lactobacillus species, were screened against a panel of popular prodrugs. All strains were capable of activating at least one prodrug. E. coli Nissle 1917 was selected for further studies because of its ability to activate numerous prodrugs and its resistance to prodrug toxicity. HPLC data confirmed biochemical transformation of prodrugs to their toxic counterparts. Further analysis demonstrated that different enzymes can complement prodrug activation, while simultaneous activation of multiple prodrugs (CB1954, 5-FC, AQ4N and Fludarabine phosphate) by E. coli was confirmed, resulting in significant efficacy improvement. Experiments in mice harbouring murine tumours validated in vitro findings, with significant reduction in tumour growth and increase in survival of mice treated with probiotic bacteria and a combination of prodrugs. These findings demonstrate the ability of probiotic bacteria, without the requirement for genetic modification, to enable high-level activation of multiple prodrugs specifically at the site of action.
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Affiliation(s)
- Panos Lehouritis
- Cork Cancer Research Centre, University College Cork, Cork, Ireland
| | - Michael Stanton
- Cork Cancer Research Centre, University College Cork, Cork, Ireland
| | - Florence O McCarthy
- Department of Chemistry and Analytical and Biological Chemistry Research Facility, University College Cork, Cork, Ireland
| | - Matthieu Jeavons
- Cork Cancer Research Centre, University College Cork, Cork, Ireland
| | - Mark Tangney
- Cork Cancer Research Centre, University College Cork, Cork, Ireland.
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15
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Cacciapuoti G, Bagarolo ML, Martino E, Scafuri B, Marabotti A, Porcelli M. Efficient Fludarabine-Activating PNP From Archaea as a Guidance for Redesign the Active Site of E. Coli PNP. J Cell Biochem 2015; 117:1126-35. [PMID: 26477689 DOI: 10.1002/jcb.25396] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/06/2015] [Indexed: 11/08/2022]
Abstract
The combination of the gene of purine nucleoside phosphorylase (PNP) from Escherichia coli and fludarabine represents one of the most promising systems in the gene therapy of solid tumors. The use of fludarabine in gene therapy is limited by the lack of an enzyme that is able to efficiently activate this prodrug which, consequently, has to be administered in high doses that cause serious side effects. In an attempt to identify enzymes with a better catalytic efficiency than E. coli PNP towards fludarabine to be used as a guidance on how to improve the activity of the bacterial enzyme, we have selected 5'-deoxy-5'-methylthioadenosine phosphorylase (SsMTAP) and 5'-deoxy-5'-methylthioadenosine phosphorylase II (SsMTAPII), two PNPs isolated from the hyperthermophilic archaeon Sulfolobus solfataricus. Substrate specificity and catalytic efficiency of SsMTAP and SsMTAPII for fludarabine were analyzed by kinetic studies and compared with E. coli PNP. SsMTAP and SsMTAPII share with E. coli PNP a comparable low affinity for the arabinonucleoside but are better catalysts of fludarabine cleavage with k(cat)/K(m) values that are 12.8-fold and 6-fold higher, respectively, than those reported for the bacterial enzyme. A computational analysis of the interactions of fludarabine in the active sites of E. coli PNP, SsMTAP, and SsMTAPII allowed to identify the crucial residues involved in the binding with this substrate, and provided structural information to improve the catalytic efficiency of E. coli PNP by enzyme redesign.
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Affiliation(s)
- Giovanna Cacciapuoti
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, Naples, 80138, Italy
| | - Maria Libera Bagarolo
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, Naples, 80138, Italy
| | - Elisa Martino
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, Naples, 80138, Italy
| | - Bernardina Scafuri
- Department of Chemistry and Biology, University of Salerno, Via Giovanni Paolo II 132, Fisciano, Salerno, 84084, Italy
| | - Anna Marabotti
- Department of Chemistry and Biology, University of Salerno, Via Giovanni Paolo II 132, Fisciano, Salerno, 84084, Italy
| | - Marina Porcelli
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, Naples, 80138, Italy
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Sahebalzamani H. A comparative study on FT-IR, conformational and electronic structure of 6-methylpurine. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 128:559-566. [PMID: 24691370 DOI: 10.1016/j.saa.2014.02.162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 02/21/2014] [Accepted: 02/23/2014] [Indexed: 06/03/2023]
Abstract
In this work, the experimental and theoretical study on molecular structure and vibrational spectra of 6-methylpurine were studied. A detailed quantum chemical calculations have been performed by Hartree-Fock (HF) and density functional theory (DFT) methods (B3LYP) with 6-31++G(d,p) basis sets. Ultraviolet-visible (UV-Vis) spectra, thermodynamic properties and Natural Bond Orbital (NBO) analysis of the title compound in the ground state have been calculated using the Hartree-Fock (HF) and density functional theory (DFT) methods (B3LYP) with 6-31++G(d,p) basis set combination for the first time. The vibrational spectra were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The results show that the vibrational frequencies are in good agreement with the experimental data. In addition, not only were frontier molecular orbitals (HOMO and LUMO), molecular electrostatic potential (MEP) and density of the state (DOS) energy band gap values were predicted.
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Affiliation(s)
- Hajar Sahebalzamani
- Young Researchers and Elite Club, Ardabil Branch, Islamic Azad University, Ardabil, Iran.
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17
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Krais JJ, De Crescenzo O, Harrison RG. Purine nucleoside phosphorylase targeted by annexin v to breast cancer vasculature for enzyme prodrug therapy. PLoS One 2013; 8:e76403. [PMID: 24098491 PMCID: PMC3789731 DOI: 10.1371/journal.pone.0076403] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 08/26/2013] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE The targeting of therapeutics is a promising approach for the development of new cancer treatments that seek to reduce the devastating side effects caused by the systemic administration of current drugs. This study evaluates a fusion protein developed as an enzyme prodrug therapy targeted to the tumor vasculature. Cytotoxicity would be localized to the site of the tumor using a protein fusion of purine nucleoside phosphorylase (PNP) and annexin V. Annexin V acts as the tumor-targeting component of the fusion protein as it has been shown to bind to phosphatidylserine expressed externally on cancer cells and the endothelial cells of the tumor vasculature, but not normal vascular endothelial cells. The enzymatic component of the fusion, PNP, converts the FDA-approved cancer therapeutic, fludarabine, into a more cytotoxic form. The purpose of this study is to determine if this system has a good potential as a targeted therapy for breast cancer. METHODS A fusion of E. coli purine nucleoside phosphorylase and human annexin V was produced in E. coli and purified. Using human breast cancer cell lines MCF-7 and MDA-MB-231 and non-confluent human endothelial cells grown in vitro, the binding strength of the fusion protein and the cytotoxicity of the enzyme prodrug system were determined. Endothelial cells that are not confluent expose phosphatidylserine and therefore mimic the tumor vasculature. RESULTS The purified recombinant fusion protein had good enzymatic activity and strong binding to the three cell lines. There was significant cell killing (p<0.001) by the enzyme prodrug treatment for all three cell lines, with greater than 80% cytotoxicity obtained after 6 days of treatment. CONCLUSION These results suggest that this treatment could be useful as a targeted therapy for breast cancer.
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Affiliation(s)
- John J. Krais
- Bioengineering Center and the School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Olivier De Crescenzo
- Bioengineering Center and the School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Roger G. Harrison
- Bioengineering Center and the School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, Oklahoma, United States of America
- Stephenson Cancer Center, Health Sciences Center, University of Oklahoma, Oklahoma City, Oklahoma, United States of America
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18
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Vande Voorde J, Liekens S, Balzarini J. Mycoplasma hyorhinis-encoded purine nucleoside phosphorylase: kinetic properties and its effect on the cytostatic potential of purine-based anticancer drugs. Mol Pharmacol 2013; 84:865-75. [PMID: 24068428 DOI: 10.1124/mol.113.088625] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A mycoplasma-encoded purine nucleoside phosphorylase (designated PNPHyor) has been cloned and characterized for the first time. Efficient phosphorolysis of natural 6-oxopurine and 6-aminopurine nucleosides was observed, with adenosine the preferred natural substrate (Km = 61 µM). Several cytostatic purine nucleoside analogs proved to be susceptible to PNPHyor-mediated phosphorolysis, and a markedly decreased or increased cytostatic activity was observed in Mycoplasma hyorhinis-infected human breast carcinoma MCF-7 cell cultures (MCF-7.Hyor), depending on the properties of the released purine base. We demonstrated an ∼10-fold loss of cytostatic activity of cladribine in MCF-7.Hyor cells and observed a rapid and complete phosphorolysis of this drug when it was exposed to the supernatant of mycoplasma-infected cells. This conversion (inactivation) could be prevented by a specific PNP inhibitor. These findings correlated well with the high efficiency of PNPHyor-catalyzed phosphorolysis of cladribine to its less toxic base 2-chloroadenine (Km = 80 µM). In contrast, the cytostatic activity of nucleoside analogs carrying a highly toxic purine base and being a substrate for PNPHyor, but not human PNP, was substantially increased in MCF-7.Hyor cells (∼130-fold for fludarabine and ∼45-fold for 6-methylpurine-2'-deoxyriboside). Elimination of the mycoplasma from the tumor cell cultures or selective inhibition of PNPHyor by a PNP inhibitor restored the cytostatic activity of the purine-based nucleoside drugs. Since several studies suggest a high and preferential colonization or association of tumor tissue in cancer patients with different prokaryotes (including mycoplasmas), the data presented here may be of relevance for the optimization of purine nucleoside-based anticancer drug treatment.
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19
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Thermus thermophilus nucleoside phosphorylases active in the synthesis of nucleoside analogues. Appl Environ Microbiol 2012; 78:3128-35. [PMID: 22344645 DOI: 10.1128/aem.07605-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cells extracts from Thermus thermophilus HB27 express phosphorolytic activities on purines and pyrimidine nucleosides. Five putative encoding genes were cloned and expressed in Escherichia coli, and the corresponding recombinant proteins were purified and studied. Two of these showed phosphorolytic activities against purine nucleosides, and third one showed phosphorolytic activity against pyrimidine nucleosides in vitro, and the three were named TtPNPI, TtPNPII, and TtPyNP, respectively. The optimal temperature for the activity of the three enzymes was beyond the water boiling point and could not be measured accurately, whereas all of them exhibited a wide plateau of optimal pHs that ranged from 5.0 to 7.0. Analytical ultracentrifugation experiments revealed that TtPNPI was a homohexamer, TtPNPII was a monomer, and TtPyNP was a homodimer. Kinetic constants were determined for the phosphorolysis of the natural substrates of each enzyme. Reaction tests with nucleoside analogues revealed critical positions in the nucleoside for its recognition. Activities with synthetic nucleobase analogues, such as 5-iodouracil or 2,6-diaminopurine, and arabinosides were detected, supporting that these enzymes could be applied for the synthesis of new nucleoside analogs with pharmacological activities.
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20
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Hassan AEA, Abou-Elkhair RAI, Riordan JM, Allan PW, Parker WB, Khare R, Waud WR, Montgomery JA, Secrist JA. Synthesis and evaluation of the substrate activity of C-6 substituted purine ribosides with E. coli purine nucleoside phosphorylase: palladium mediated cross-coupling of organozinc halides with 6-chloropurine nucleosides. Eur J Med Chem 2011; 47:167-74. [PMID: 22112758 DOI: 10.1016/j.ejmech.2011.10.039] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 10/14/2011] [Accepted: 10/19/2011] [Indexed: 11/19/2022]
Abstract
A series of C-6 alkyl, cycloalkyl, and aryl-9-(β-d-ribofuranosyl)purines were synthesized and their substrate activities with Escherichia coli purine nucleoside phosphorylase (E. coli PNP) were evaluated. (Ph(3)P)(4)Pd-mediated cross-coupling reactions of 6-chloro-9-(2,3,5-tri-O-acetyl-β-d-ribofuranosyl)-purine (6) with primary alkyl (Me, Et, n-Pr, n-Bu, isoBu) zinc halides followed by treatment with NH(3)/MeOH gave the corresponding 6-alkyl-9-(β-d-ribofuranosyl)purine derivatives 7-11, respectively, in good yields. Reactions of 6 with cycloalkyl(propyl, butyl, pentyl)zinc halides and aryl (phenyl, 2-thienyl)zinc halides gave under similar conditions the corresponding 6-cyclopropyl, cyclobutyl, cyclopentyl, phenyl, and thienyl -9-(β-d-ribofuranosyl)purine derivatives 12-16, respectively in high yields. E. coli PNP showed a high tolerance to the steric and hydrophobic environment at the 6-position of the synthesized purine ribonucleosides. Significant cytotoxic activity was observed for 8, 12, 15, and 16. Evaluation of 12 and 16 against human tumor xenografts in mice did not demonstrate any selective antitumor activity. In addition, 6-methyl-9-(β-d-arabinofuranosyl)purine (18) was prepared and evaluated.
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Affiliation(s)
- Abdalla E A Hassan
- Drug Discovery Division, Southern Research Institute, P.O. Box 55305, Birmingham, AL 35255-5305, USA
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21
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Yang YH, Aloysius H, Inoyama D, Chen Y, Hu LQ. Enzyme-mediated hydrolytic activation of prodrugs. Acta Pharm Sin B 2011. [DOI: 10.1016/j.apsb.2011.08.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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22
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Castro MG, Candolfi M, Kroeger K, King GD, Curtin JF, Yagiz K, Mineharu Y, Assi H, Wibowo M, Ghulam Muhammad AKM, Foulad D, Puntel M, Lowenstein PR. Gene therapy and targeted toxins for glioma. Curr Gene Ther 2011; 11:155-80. [PMID: 21453286 DOI: 10.2174/156652311795684722] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 03/08/2011] [Indexed: 12/12/2022]
Abstract
The most common primary brain tumor in adults is glioblastoma. These tumors are highly invasive and aggressive with a mean survival time of 15-18 months from diagnosis to death. Current treatment modalities are unable to significantly prolong survival in patients diagnosed with glioblastoma. As such, glioma is an attractive target for developing novel therapeutic approaches utilizing gene therapy. This review will examine the available preclinical models for glioma including xenographs, syngeneic and genetic models. Several promising therapeutic targets are currently being pursued in pre-clinical investigations. These targets will be reviewed by mechanism of action, i.e., conditional cytotoxic, targeted toxins, oncolytic viruses, tumor suppressors/oncogenes, and immune stimulatory approaches. Preclinical gene therapy paradigms aim to determine which strategies will provide rapid tumor regression and long-term protection from recurrence. While a wide range of potential targets are being investigated preclinically, only the most efficacious are further transitioned into clinical trial paradigms. Clinical trials reported to date are summarized including results from conditionally cytotoxic, targeted toxins, oncolytic viruses and oncogene targeting approaches. Clinical trial results have not been as robust as preclinical models predicted; this could be due to the limitations of the GBM models employed. Once this is addressed, and we develop effective gene therapies in models that better replicate the clinical scenario, gene therapy will provide a powerful approach to treat and manage brain tumors.
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Affiliation(s)
- Maria G Castro
- Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
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Effect of expression of adenine phosphoribosyltransferase on the in vivo anti-tumor activity of prodrugs activated by E. coli purine nucleoside phosphorylase. Cancer Gene Ther 2011; 18:390-8. [PMID: 21394111 PMCID: PMC3096718 DOI: 10.1038/cgt.2011.4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The use of E. coli purine nucleoside phosphorylase (PNP) to activate prodrugs has demonstrated excellent activity in the treatment of various human tumor xenografts in mice. E. coli PNP cleaves purine nucleoside analogs to generate toxic adenine analogs, which are activated by adenine phosphoribosyl transferase (APRT) to metabolites that inhibit RNA and protein synthesis. We created tumor cell lines that encode both E. coli PNP and excess levels of human APRT, and have used these new cell models to test the hypothesis that treatment of otherwise refractory human tumors could be enhanced by overexpression of APRT. In vivo studies with 6-methylpurine-2′-deoxyriboside (MeP-dR), 2-F-2′-deoxyadenosine (F-dAdo) or 9-β-D-arabinofuranosyl-2-fluoroadenine 5′-monophosphate (F-araAMP) indicated that increased APRT in human tumor cells coexpressing E. coli PNP did not enhance either the activation or the anti-tumor activity of any of the three prodrugs. Interestingly, expression of excess APRT in bystander cells improved the activity of MeP-dR, but diminished the activity of F-araAMP. In vitro studies indicated that increasing the expression of APRT in the cells did not significantly increase the activation of MeP. These results provide insight into the mechanism of bystander killing of the E. coli PNP strategy, and suggest ways to enhance the approach that are independent of APRT.
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Jang SJ, Kang JH, Lee TS, Kim SJ, Kim KI, Lee YJ, Cheon GJ, Choi CW, Lim SM. Prodrug-activating Gene Therapy with Rabbit Cytochrome P450 4B1/4-Ipomeanol or 2-Aminoanthracene System in Glioma Cells. Nucl Med Mol Imaging 2010; 44:193-8. [PMID: 24899949 DOI: 10.1007/s13139-010-0038-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Revised: 05/19/2010] [Accepted: 05/24/2010] [Indexed: 10/19/2022] Open
Abstract
OBJECTIVE We determined the cytotoxic properties of cytochrome P450 4B1 (CYP4B1) activated 4-ipomeanol (4-ipo) and 2-aminoanthracene (2-AA) in rat glioma to verify the CYP4B1/4-ipo or 2-AA system for prodrug-activating gene therapy. METHODS The cyp4B1 cDNA was cloned into pcDNA3.1/Hygro from rabbit lung total RNA (pcDNA-cyp4B1). Lentiviral vector encoding firefly luciferase (fLuc) was infected into C6 (rat glioma), and the fLuc-expressing cell was selected (C6-L). After transfection with pcDNA-cyp4B1 vector into C6-L, the single clone expressing cyp4B1 gene was selected (C6-CL). Prodrug for various concentrations of 4-ipo or 2-AA was treated for 72 h and 96 h. The cell survival rate of C6-CL was determined using MTT assay and trypan-blue dye exclusion methods. RESULTS By RT-PCR analysis, fLuc and CYP4B1 expression was detected in C6-CL, but not in C6. MTT assay and trypan-blue dye exclusion showed that IC50 of C6-CL was 0.3 mM and <0.01 mM after 4-ipo or 2-AA treatment at 96 h or 72 h exposure, respectively. Cell survivals of C6-CL were more rapidly reduced after treatment with 4-ipo or 2-AA than those of C6-L cells. The cell survival rate with MTT and trypan-blue dye exclusion assay was well correlated with fLuc activity in C6-CL cells. CONCLUSION CYP4B1-based prodrug-activating gene therapy may have the potential to treat glioma and the cytotoxic effects of CYP4B1 enzyme activated 4-ipo or 2-AA in C6, and could be clearly determined by bioluminescent activity in C6-CL.
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Affiliation(s)
- Su Jin Jang
- Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea
| | - Joo Hyun Kang
- Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea
| | - Tae Sup Lee
- Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea
| | - Sung Joo Kim
- Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea
| | - Kwang Il Kim
- Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea
| | - Yong Jin Lee
- Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea
| | - Gi Jeong Cheon
- Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea ; Department of Nuclear Medicine, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea
| | - Chang Woon Choi
- Department of Nuclear Medicine, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea
| | - Sang Moo Lim
- Department of Nuclear Medicine, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Gongneung-Dong, Nowon-Gu, Seoul, 139-706 Republic of Korea
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Enhanced efficiency of prodrug activation therapy by tumor-selective replicating retrovirus vectors armed with the Escherichia coli purine nucleoside phosphorylase gene. Cancer Gene Ther 2010; 17:614-23. [PMID: 20467451 DOI: 10.1038/cgt.2010.17] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Gene transfer of the Escherichia coli purine nucleoside phosphorylase (PNP) results in potent cytotoxicity after administration of the prodrug fludarabine phosphate (F-araAMP). Here, we have tested whether application of this strategy in the context of replication-competent retrovirus (RCR) vectors, which can achieve highly efficient tumor-restricted transduction as well as persistent expression of transgenes, would result in effective tumor inhibition, or, alternatively, would adversely affect viral replication. We found that RCR vectors could achieve high levels of PNP expression concomitant with the efficiency of their replicative spread, with significant cell killing activity in vitro and potent therapeutic effects in vivo. In U-87 xenograft models, replicative spread of the vector resulted in progressive transmission of the PNP transgene, as evidenced by increasing PNP enzyme activity with time after vector inoculation. On F-araAMP administration, high efficiency gene transfer of PNP by the RCR vector resulted in significant suppression of tumor growth and extended survival time. As the RCR mediates stable integration of the PNP gene and continuous expression, an additional round of F-araAMP administration resulted in further survival benefit. RCR-mediated PNP suicide gene therapy thus represents a highly efficient form of intracellular chemotherapy, and may achieve effective antitumor activity with less systemic toxicity.
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Hassan AEA, Parker WB, Allan PW, Secrist JA. Regioselective metalation of 6-methylpurines: synthesis of fluoromethyl purines and related nucleosides for suicide gene therapy of cancer. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2010; 28:642-56. [PMID: 20183607 DOI: 10.1080/15257770903091938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Metalation of 6-methyl-9-(tetrahydro-2H-pyran-2-yl)purine (10) with lithiating agents of varying basicities such as n-BuLi and LiHMDS in THF at -78 degrees C resulted in metalation at both of the 6-CH(3) moiety and the 8-CH position, irrespective of the molar equivalence of the base. On the other hand, a regioselective metalation at the 6-CH(3) moiety of 10 was observed with NaHMDS or KHMDS, under similar conditions. Treatment of the potassium salts of 10 and of the protected riboside derivative 6-methyl-9-(beta-D-2,3,5-tri-O-tert-butyldimethylsilylribofuranosyl)purine (22) with N-fluorobenzenesulfonamide (NFSI) at -78 degrees C gave the corresponding 6-fluoromethylpurine derivatives 11 and 23, respectively, in good yields. Deprotection of 11 and 23 under standard conditions gave 6-fluoromethylpurine (6-FMeP, 3) and 6-fluoromethyl-9-(beta-D-ribofuranosyl)purine (6-FMePR, 4), respectively, in high yield. Both 3 and 4 demonstrated cytotoxic activity against CCRF-CEM cells in culture. 6-FMePR is a good substrate for E. coli purine nucleoside phosphorylase (E. coli PNP) with a comparable substrate activity to that of the parent nucleoside, 6-methyl-9-(beta-D-ribofuranosyl)purine (6-MePR, 21). The cytotoxic activity of 6-FMeP along with the substrate activity of 6-FMePR with E. coli PNP meet the fundamental requirements for using 6-FMeP as a potential toxin in PNP/prodrug based cancer gene therapy.
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Affiliation(s)
- Abdalla E A Hassan
- Southern Research Institute, Drug Discovery Division, Birmingham, Alabama, USA
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Development of gene therapy in association with clinically used cytotoxic deoxynucleoside analogues. Cancer Gene Ther 2009; 16:541-50. [PMID: 19343063 DOI: 10.1038/cgt.2009.25] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The clinical use of cytotoxic deoxynucleoside analogues is often limited by resistance mechanisms due to enzymatic deficiency, or high toxicity in nontumor tissues. To improve the use of these drugs, gene therapy approaches have been proposed and studied, associating clinically used deoxynucleoside analogues such as araC and gemcitabine and suicide genes or myeloprotective genes. In this review, we provide an update of recent results in this area, with particular emphasis on human deoxycytidine kinase, the deoxyribonucleoside kinase from Drosophila melanogaster, purine nucleoside phosphorylase from Escherichia coli, and human cytidine deaminase. Data from literature clearly show the feasibility of these systems, and clinical trials are warranted to conclude on their use in the treatment of cancer patients.
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Kuchař M, Pohl R, Klepetářová B, Hocek M. Synthesis of diverse 6-(1,2-disubstituted ethyl)purine bases and nucleosides via 6-(oxiran-2-yl)purines. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.08.074] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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29
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Fu W, Lan H, Liang S, Gao T, Ren D. Suicide gene/prodrug therapy using salmonella-mediated delivery ofEscherichia colipurine nucleoside phosphorylase gene and 6-methoxypurine 2′-deoxyriboside in murine mammary carcinoma 4T1 model. Cancer Sci 2008; 99:1172-9. [DOI: 10.1111/j.1349-7006.2008.00808.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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30
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Fu W, Lan H, Li S, Han X, Gao T, Ren D. Synergistic antitumor efficacy of suicide/ePNP gene and 6-methylpurine 2'-deoxyriboside via Salmonella against murine tumors. Cancer Gene Ther 2008; 15:474-84. [PMID: 18437183 DOI: 10.1038/cgt.2008.19] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Some anaerobes and facultative anaerobes have been used in tumor-specific gene therapy by reason of their selective growth in tumors. In this work, we aimed to evaluate the anticancer efficacy of attenuated Salmonella typhimurium as a carrier to deliver the Escherichia coli purine nucleoside phosphorylase (ePNP) gene for GDEPT (gene-directed enzyme-prodrug therapy). A live attenuated purine-auxotrophic strain of S. typhimurium (SC36) was used to carry the pEGFP-C1-ePNP vector that contains a green fluorescent protein (GFP) and an ePNP gene under the control of the human cytomegalovirus (CMV) promoter. The function of the ePNP expression vector was confirmed in vitro using the enzymic conversion of 6-methylpurine 2'-deoxyriboside (MePdR) into 6-methylpurine. We also observed a high bystander effect induced by the ePNP/MePdR system with a very low proportion (1%) of ePNP-positive cells. The killing effect and increased apoptosis induced by SC/ePNP (SC36 carrying the ePNP expression vector) infection were detected by cytotoxicity assay and PI staining flow cytometry analysis, in combination with MePdR administration. Furthermore, SC/ePNP was administered orally into mice bearing melanomas or pulmonary tumors, and its anti-tumor effect was evaluated. When the tumor was huge (500 mm(3)) at the beginning of MePdR administration, SC/ePNP plus MepdR significantly inhibited tumor growth by about 59-80% and prolonged survival of mice. Complete tumor regression and long-term cure were achieved by MePdR administration, even when the tumor was large (100 mm(3)) at the beginning of MePdR treatment. Our data support a hopeful view that tumor-targeting SC36 could improve antitumor efficacy of the ePNP/MePdR system due to its preferential accumulation and anticancer activity in tumors.
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Affiliation(s)
- W Fu
- State Key Lab of Genetic Engineering, Department of Genetics, Fudan University, Shanghai, China
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31
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Stritzker J, Pilgrim S, Szalay AA, Goebel W. Prodrug converting enzyme gene delivery by L. monocytogenes. BMC Cancer 2008; 8:94. [PMID: 18402662 PMCID: PMC2329648 DOI: 10.1186/1471-2407-8-94] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Accepted: 04/10/2008] [Indexed: 11/10/2022] Open
Abstract
Background Listeria monocytogenes is a highly versatile bacterial carrier system for introducing protein, DNA and RNA into mammalian cells. The delivery of tumor antigens with the help of this carrier into tumor-bearing animals has been successfully carried out previously and it was recently reported that L. monocytogenes is able to colonize and replicate within solid tumors after local or even systemic injection. Methods Here we report on the delivery of two prodrug converting enzymes, purine-deoxynucleoside phosphorylase (PNP) and a fusion protein consisting of yeast cytosine deaminase and uracil phosphoribosyl transferase (FCU1) into cancer cells in culture by L. monocytogenes. Transfer of the prodrug converting enzymes was achieved by bacterium mediated transfer of eukaryotic expression plasmids or by secretion of the proteins directly into the host cell cytosol by the infecting bacteria. Results The results indicate that conversion of appropriate prodrugs to toxic drugs in the cancer cells occured after both procedures although L. monocytogenes-mediated bactofection proved to be more efficient than enzyme secretion 4T1, B16 and COS-1 tumor cells. Exchanging the constitutively PCMV-promoter with the melanoma specific P4xTETP-promoter resulted in melanoma cell-specific expression of the prodrug converting enzymes but reduced the efficiencies. Conclusion These experiments open the way for bacterium mediated tumor specific activation of prodrugs in live animals with tumors.
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Affiliation(s)
- Jochen Stritzker
- Biocenter (Microbiology), University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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32
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Kuchař M, Pohl R, Klepetářová B, Votruba I, Hocek M. Synthesis of substituted 6-cyclopropylpurine bases and nucleosides by cross-coupling reactions or cyclopropanations. Org Biomol Chem 2008; 6:2377-87. [DOI: 10.1039/b802833h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Synthesis of (purin-6-yl)acetates and 6-(2-hydroxyethyl)purines via cross-couplings of 6-chloropurines with the Reformatsky reagent. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2007.06.053] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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34
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Cacciapuoti G, Gorassini S, Mazzeo MF, Siciliano RA, Carbone V, Zappia V, Porcelli M. Biochemical and structural characterization of mammalian-like purine nucleoside phosphorylase from the Archaeon Pyrococcus furiosus. FEBS J 2007; 274:2482-95. [PMID: 17419725 DOI: 10.1111/j.1742-4658.2007.05784.x] [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: 11/27/2022]
Abstract
We report here the characterization of the first mammalian-like purine nucleoside phosphorylase from the hyperthermophilic archaeon Pyrococcus furiosus (PfPNP). The gene PF0853 encoding PfPNP was cloned and expressed in Escherichia coli and the recombinant protein was purified to homogeneity. PfPNP is a homohexamer of 180 kDa which shows a much higher similarity with 5'-deoxy-5'-methylthioadenosine phosphorylase (MTAP) than with purine nucleoside phosphorylase (PNP) family members. Like human PNP, PfPNP shows an absolute specificity for inosine and guanosine. PfPNP shares 50% identity with MTAP from P. furiosus (PfMTAP). The alignment of the protein sequences of PfPNP and PfMTAP indicates that only four residue changes are able to switch the specificity of PfPNP from a 6-oxo to a 6-amino purine nucleoside phosphorylase still maintaining the same overall active site organization. PfPNP is highly thermophilic with an optimum temperature of 120 degrees C and is characterized by extreme thermodynamic stability (T(m), 110 degrees C that increases to 120 degrees C in the presence of 100 mm phosphate), kinetic stability (100% residual activity after 4 h incubation at 100 degrees C), and remarkable SDS-resistance. Limited proteolysis indicated that the only proteolytic cleavage site is localized in the C-terminal region and that the C-terminal peptide is not necessary for the integrity of the active site. By integrating biochemical methodologies with mass spectrometry we assigned three pairs of intrasubunit disulfide bridges that play a role in the stability of the enzyme against thermal inactivation. The characterization of the thermal properties of the C254S/C256S mutant suggests that the CXC motif in the C-terminal region may also account for the extreme enzyme thermostability.
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Affiliation(s)
- Giovanna Cacciapuoti
- Dipartimento di Biochimica e Biofisica F. Cedrangolo, Seconda Università di Napoli, Napoli, Italy.
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35
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Hocek M, Silhár P. Palladium-catalyzed cross-coupling reactions in c6 modifications of purine nucleosides. CURRENT PROTOCOLS IN NUCLEIC ACID CHEMISTRY 2007; Chapter 1:Unit 1.16. [PMID: 18428964 DOI: 10.1002/0471142700.nc0116s28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This unit describes the cross-coupling methodology for introduction of diverse C-substituents to position 6 of purine nucleosides. Protected 6-chloropurine nucleosides undergo Pd-catalyzed cross-coupling reactions with trialkylaluminium, alkylzinc halides, aryl(tributyl)stannanes, and arylboronic acids to give the corresponding 6-substituted intermediates, which can be deprotected by treatment with NaOMe. (Acetyloxy)methylzinc iodide is used for introduction of the hydroxymethyl group, which can further be transformed to fluoromethyl and difluoromethyl groups. Most of the title 6-substituted purine ribonucleosides possess cytostatic and/or anti-HCV activity.
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Affiliation(s)
- Michal Hocek
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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36
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Kikuchi E, Menendez S, Ozu C, Ohori M, Cordon-Cardo C, Logg CR, Kasahara N, Bochner BH. Delivery of replication-competent retrovirus expressing Escherichia coli purine nucleoside phosphorylase increases the metabolism of the prodrug, fludarabine phosphate and suppresses the growth of bladder tumor xenografts. Cancer Gene Ther 2007; 14:279-86. [PMID: 17218950 DOI: 10.1038/sj.cgt.7701013] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We have developed unique replication-competent retroviral (RCR) vectors based on murine leukemia virus that provide improved efficiency of viral delivery, allow for long-term transgene expression and demonstrate an intrinsic selectivity for transduction of rapidly dividing tumor cells. The purpose of this study was to evaluate the in vivo transduction efficiency and the therapeutic efficacy of the RCR vector mediated delivery of Escherichia coli purine nucleoside phosphorylase (PNP) in combination with fludarabine phosphate for bladder cancer. We constructed vectors containing green fluorescent protein (GFP) gene (ACE)-GFP) or PNP gene (ACE-PNP). KU-19-19 bladder tumors exhibited 28.3+/-16.1, 46.6+/-5.8 and 93.7+/-7.8% of GFP expression on 14, 18 and 26 days after intratumoral injection of ACE-GFP, respectively. GFP expression could not be observed in normal tissues surrounding the injected tumors. No detectable polymerase chain reaction products of GFP gene could be observed in any distant organs. Intratumoral injection of ACE-PNP, followed by systemically administered fludarabine phosphate, significantly inhibited the growth of pre-established KU-19-19 tumors. Our results indicate that RCR vectors are a potentially efficient gene delivery method and that the RCR vector mediated PNP gene transfer and fludarabine phosphate treatment might be a novel and potentially therapeutic modality for bladder cancer.
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Affiliation(s)
- E Kikuchi
- Department of Urology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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37
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Portsmouth D, Hlavaty J, Renner M. Suicide genes for cancer therapy. Mol Aspects Med 2007; 28:4-41. [PMID: 17306358 DOI: 10.1016/j.mam.2006.12.001] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Accepted: 12/18/2006] [Indexed: 12/31/2022]
Abstract
The principle of using suicide genes for gene directed enzyme prodrug therapy (GDEPT) of cancer has gained increasing significance during the 20 years since its inception. The astute application of suitable GDEPT systems should permit tumour ablation in the absence of off-target toxicity commonly associated with classical chemotherapy, a hypothesis which is supported by encouraging results in a multitude of pre-clinical animal models. This review provides a clear explanation of the rationale behind the GDEPT principle, outlining the advantages and limitations of different GDEPT strategies with respect to the roles of the bystander effect, the immune system and the selectivity of the activated prodrug in contributing to their therapeutic efficacy. An in-depth analysis of the most widely used suicide gene/prodrug combinations is presented, including details of the latest advances in enzyme and prodrug optimisation and results from the most recent clinical trials.
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Affiliation(s)
- Daniel Portsmouth
- Research Institute for Virology and Biomedicine, University of Veterinary Medicine, Vienna, Austria
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38
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Modrak-Wójcik A, Stepniak K, Akoev V, Zółkiewski M, Bzowska A. Molecular architecture of E. coli purine nucleoside phosphorylase studied by analytical ultracentrifugation and CD spectroscopy. Protein Sci 2006; 15:1794-800. [PMID: 16751611 PMCID: PMC2242567 DOI: 10.1110/ps.062183206] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Purine nucleoside phosphorylase (PNP) is a key enzyme of the nucleoside salvage pathway and is characterized by complex kinetics. It was suggested that this is due to coexistence of various oligomeric forms that differ in specific activity. In this work, the molecular architecture of Escherichia coli PNP in solution was studied by analytical ultracentrifugation and CD spectroscopy. Sedimentation equilibrium analysis revealed a homohexameric molecule with molecular mass 150+/-10 kDa, regardless of the conditions investigated-protein concentration, 0.18-1.7 mg/mL; presence of up to 10 mM phosphate and up to 100 mM KCl; temperature, 4-20 degrees C. The parameters obtained from the self-associating model also describe the hexameric form. Sedimentation velocity experiments conducted for broad protein concentration range (1 microg/mL-1.3 mg/mL) with boundary (classical) and band (active enzyme) approaches gave s(0)20,w=7.7+/-0.3 and 8.3+/-0.4 S, respectively. The molecular mass of the sedimenting particle (146+/-30 kDa), calculated using the Svedberg equation, corresponds to the mass of the hexamer. Relative values of the CD signal at 220 nm and the catalytic activity of PNP as a function of GdnHCl concentration were found to be correlated. The transition from the native state to the random coil is a single-step process. The sedimentation coefficient determined at 1 M GdnHCl (at which the enzyme is still fully active) is 7.7 S, showing that also under these conditions the hexamer is the only catalytically active form. Hence, in solution similar to the crystal, E. coli PNP is a hexameric molecule and previous suggestions for coexistence of two oligomeric forms are incorrect.
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Affiliation(s)
- Anna Modrak-Wójcik
- Department of Biophysics, Institute of Experimental Physics, University of Warsaw, Poland
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Synthesis of novel 2-(2-(6-chloro-9H-purin-9-yl)ethoxy)-6-isobutoxy-tetrahydro-2H-pyran-3-ol as a potential antiviral agent. MOLBANK 2006. [DOI: 10.3390/m481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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40
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King GD, Curtin JF, Candolfi M, Kroeger K, Lowenstein PR, Castro MG. Gene therapy and targeted toxins for glioma. Curr Gene Ther 2006; 5:535-57. [PMID: 16457645 PMCID: PMC1629033 DOI: 10.2174/156652305774964631] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The most common primary brain tumor in adults is glioblastoma. These tumors are highly invasive and aggressive with a mean survival time of nine to twelve months from diagnosis to death. Current treatment modalities are unable to significantly prolong survival in patients diagnosed with glioblastoma. As such, glioma is an attractive target for developing novel therapeutic approaches utilizing gene therapy. This review will examine the available preclinical models for glioma including xenographs, syngeneic and genetic models. Several promising therapeutic targets are currently being pursued in pre-clinical investigations. These targets will be reviewed by mechanism of action, i.e., conditional cytotoxic, targeted toxins, oncolytic viruses, tumor suppressors/oncogenes, and immune stimulatory approaches. Preclinical gene therapy paradigms aim to determine which strategies will provide rapid tumor regression and long-term protection from recurrence. While a wide range of potential targets are being investigated preclinically, only the most efficacious are further transitioned into clinical trial paradigms. Clinical trials reported to date are summarized including results from conditionally cytotoxic, targeted toxins, oncolytic viruses and oncogene targeting approaches. Clinical trial results have not been as robust as preclinical models predicted, this could be due to the limitations of the GBM models employed. Once this is addressed, and we develop effective gene therapies in models that better replicate the clinical scenario, gene therapy will provide a powerful approach to treat and manage brain tumors.
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Affiliation(s)
- Gwendalyn D King
- Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, UCLA, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA
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Šilhár P, Pohl R, Votruba I, Klepetářová B, Hocek M. Synthesis of 6-Amino-, 6-Methyl- and 6-Aryl-2-(hydroxymethyl)purine Bases and Nucleosides. ACTA ACUST UNITED AC 2006. [DOI: 10.1135/cccc20060788] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
An efficient methodology of the synthesis of 6-substituted 2-(hydroxymethyl)purine derivatives (bases and nucleosides) was developed. Regioselective Pd-catalyzed cross-coupling reactions of 6-chloro-2-iodopurines with [(benzoyloxy)methyl]zinc iodide gave 2-[(benzoyloxy)-methyl]-6-chloropurines that were converted to 2-(hydroxymethyl)adenines by reactions with ammonia and to 6-methyl- or 6-aryl-2-(hydroxymethyl)purines by cross-coupling reactions with trimethylaluminium or arylboronic acids followed by deprotection. The title 6-substituted 2-(hydroxymethyl)purine bases and nucleosides did not exhibit significant cytostatic or anti-HCV activity.
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Parker WB, Allan PW, Ealick SE, Sorscher EJ, Hassan AEA, Silamkoti AV, Fowler AT, Waud WR, Secrist JA. Design and evaluation of 5'-modified nucleoside analogs as prodrugs for an E. coli purine nucleoside phosphorylase mutant. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2005; 24:387-92. [PMID: 16247956 DOI: 10.1081/ncn-200059807] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Our studies have led to the identification of an E. coli PNP mutant (M64V) that is able to cleave numerous 5'-modified nucleoside analogs with much greater efficiency than the wild-type enzyme. The biological activity of the three best substrates of this mutant (9-[6-deoxy-alpha-L-talofuranosyl]-6-methylpurine (methyl(talo)-MeP-R), 9-[6-deoxy-alpha-L-talofuranosyl]-2-F-adenine, and 9-[alpha-L-lyxofuranosyl]-2-F-adenine) were evaluated so that we can optimally utilize these compounds. Our results indicated that the mechanism of toxicity of methyl(talo)-MeP-R to mice was due to its cleavage to MeP by a bacterial enzyme, and that the toxicity of the two F-Ade analogs was due to their cleavage to F-Ade by mammalian methylthioadenosine phosphorylase.
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Affiliation(s)
- William B Parker
- Southern Research Institute, 2000 Ninth Ave., South, Birmingham, AL 35205, USA.
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43
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Sorscher EJ, Harris J, Alexander M, Rottgers A, Hardy K, Ponnazhagan S, Collawn JF, McClintock J, Amsler CD, Webster A, Maddry J, Baker BJ, Hong JS. Activators of viral gene expression in polarized epithelial monolayers identified by rapid-throughput drug screening. Gene Ther 2005; 13:781-8. [PMID: 16307002 DOI: 10.1038/sj.gt.3302676] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epithelial polarity and tight junction formation limit the ability of adenovirus, retrovirus and adeno-associated virus (AAV) to deliver and express virally encoded genes. Using an extended half-life luciferase assay and high-throughput luminometry, we screened 23 000 compounds and natural product extracts as potentiators to overcome this barrier. Seven strong activators were discovered (up to several hundred fold above control) and two of these exhibited spectrum of activity in multiple cell types (HeLa (human cervical carcinoma), cystic fibrosis bronchial epithelial (human bronchial), HT29 (human colonic carcinoma), Calu3 (airway serous glandular)). Enhanced transduction by unrelated gene transfer vectors (adenovirus, lentivirus, AAV, liposomal) was also observed. These results establish a strategy for identifying compounds that improve viral gene transfer to resistant cell types, and provide new tools for examining epithelial defense against viral infection. The compounds should have broad usefulness in experimental therapies for cancer and genetic diseases.
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Affiliation(s)
- E J Sorscher
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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44
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Deharvengt S, Wack S, Aprahamian M, Hajri A. Transcriptional tumor-selective promoter targeting of E. coli purine nucleoside phosphorylase for pancreatic cancer suicide gene therapy. J Gene Med 2005; 7:672-80. [PMID: 15580629 DOI: 10.1002/jgm.701] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Pancreatic cancer remains a rapidly fatal disease. Suicide gene therapy has been shown to be an effective tool for pancreatic tumor cell destruction, but a cell-specific gene delivery is required to limit host toxicity. The objective of this study was both to design recombinant vectors in which the suicide gene E. coli purine nucleoside phosphorylase (ePNP) is under the control of either CEA or MUC1 promoter sequences and to investigate on experimental pancreatic carcinomas the selective killing effects of the conditional ePNP/prodrug (MePdR) system. METHODS Transcriptional activities of CEA and MUC1 promoter sequences were analyzed using luciferase reporter gene constructions. Thereafter, recombinant vectors expressing ePNP under control of the most promising pCEA and pMUC1 sequences were designed and used to establish stable tumor cell transfectants from two human pancreatic cell lines, respectively tumor-marker positive (BxPc3) or negative (Panc-1), then applied for in vitro and in vivo experiments. RESULTS Transient experiments indicated that CEA and MUC1 promoter sequences confer specificity while preserving high transcriptional activities. The MePdR treatment induced a high in vitro cytotoxicity on the sole CEA- and MUC1-producing cell lines (i.e. BxPc3-CEA and -MUC1/ePNP). In the same way, prodrug treatment induced a significant tumor regression on the sole tumor-marker-positive BxPc3 xenografts, whilst the Panc1-CEA and -MUC1/ePNP tumors were not affected. CONCLUSIONS These data confirm and extend the antitumor efficacy of the ePNP/MePdR killing system and demonstrate the feasibility of the transcriptional targeting strategy under tumor marker promoter control and thereby a preferential killing of CEA- and MUC1-producing pancreatic tumor cells. Thus, efficient in vivo gene delivery and transcriptional targeting constitute the major future clinical challenge for a selective pancreatic cancer suicide gene strategy.
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Affiliation(s)
- Sophie Deharvengt
- INSERM U375, IRCAD, 1 place de l'Hôpital, BP 426, 67091 Strasbourg Cedex, France
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Bharara S, Sorscher EJ, Gillespie GY, Lindsey JR, Hong JS, Curlee KV, Allan PW, Gadi VK, Alexander SA, Secrist JA, Parker WB, Waud WR. Antibiotic-mediated chemoprotection enhances adaptation of E. coli PNP for herpes simplex virus-based glioma therapy. Hum Gene Ther 2005; 16:339-47. [PMID: 15812229 DOI: 10.1089/hum.2005.16.339] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The E. coli PNP suicide gene sensitizes solid tumors to nucleoside prodrugs, such as 6-methylpurine-2'-deoxyriboside (MeP-dR). In this study using lentiviral, MuLv, and HSV-based gene transfer, we quantified thresholds for inhibition of tumor growth and bystander killing by E. coli PNP and tested the role of intestinal flora in this process. Regressions of human glioma tumors following retroviral transduction exhibited dose dependence on both the level of PNP expression and the dose of MeP-dR administered, including strong tumor inhibition when 90-99% bystander cells comprised the tumor mass. A replication competent, non-neurovirulent herpes simplex virus (HSV) deficient in both copies of the gamma-1 34.5 gene was next engineered to express E. coli PNP under the egr-1 promoter (HSV-PNP). HSV-PNP injected intratumorally (17 million pfu/0.05 ml) in nude mice bearing 300 mg human glioma flank tumors produced a delay in tumor growth (approximately 24 days delay to one doubling). MeP-dR treatment after antibiotic therapy (to eliminate enteric flora encoding PNP enzymes) resulted in antitumor enhancement, with arrest of tumor growth (delay to doubling >50 days). Bystander killing of the magnitude described here has been difficult to accomplish with other suicide genes, such as HSV-tk or cytosine deaminase. The results establish a model for applying E. coli PNP to HSV treatment of glioma.
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Affiliation(s)
- Suman Bharara
- Department of Surgery, University of Alabama at Birmingham, AL 35294, USA
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Hocek M, Pohl R, Císařová I. Highly Methylated Purines and Purinium Salts as Analogues of Heteromines. European J Org Chem 2005. [DOI: 10.1002/ejoc.200500154] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Zang Y, Wang WH, Wu SW, Ealick SE, Wang CC. Identification of a subversive substrate of Trichomonas vaginalis purine nucleoside phosphorylase and the crystal structure of the enzyme-substrate complex. J Biol Chem 2005; 280:22318-25. [PMID: 15817485 DOI: 10.1074/jbc.m501843200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Trichomonas vaginalis is an anaerobic protozoan parasite that causes trichomoniasis, a common sexually transmitted disease with worldwide impact. One of the pivotal enzymes in its purine salvage pathway, purine nucleoside phosphorylase (PNP), shows physical properties and substrate specificities similar to those of the high molecular mass bacterial PNPs but differing from those of human PNP. While carrying out studies to identify inhibitors of T. vaginalis PNP (TvPNP), we discovered that the nontoxic nucleoside analogue 2-fluoro-2'-deoxyadenosine (F-dAdo) is a "subversive substrate." Phosphorolysis by TvPNP of F-dAdo, which is not a substrate for human PNP, releases highly cytotoxic 2-fluoroadenine (F-Ade). In vitro studies showed that both F-dAdo and F-Ade exert strong inhibition of T. vaginalis growth with estimated IC(50) values of 106 and 84 nm, respectively, suggesting that F-dAdo might be useful as a potential chemotherapeutic agent against T. vaginalis. To understand the basis of TvPNP specificity, the structures of TvPNP complexed with F-dAdo, 2-fluoroadenosine, formycin A, adenosine, inosine, or 2'-deoxyinosine were determined by x-ray crystallography with resolutions ranging from 2.4 to 2.9 A. These studies showed that the quaternary structure, monomer fold, and active site are similar to those of Escherichia coli PNP. The principal active site difference is at Thr-156, which is alanine in E. coli PNP. In the complex of TvPNP with F-dAdo, Thr-156 causes the purine base to tilt and shift by 0.5 A as compared with the binding scheme of F-dAdo in E. coli PNP. The structures of the TvPNP complexes suggest opportunities for further improved subversive substrates beyond F-dAdo.
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Affiliation(s)
- Yang Zang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
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Wang XY, Martiniello-Wilks R, Shaw JM, Ho T, Coulston N, Cooke-Yarborough C, Molloy PL, Cameron F, Moghaddam M, Lockett TJ, Webster LK, Smith IK, Both GW, Russell PJ. Preclinical evaluation of a prostate-targeted gene-directed enzyme prodrug therapy delivered by ovine atadenovirus. Gene Ther 2005; 11:1559-67. [PMID: 15343359 DOI: 10.1038/sj.gt.3302308] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Gene-directed enzyme prodrug therapy (GDEPT) based on the Escherichia coli enzyme, purine nucleoside phosphorylase (PNP), provides a novel strategy for treating slowly growing tumors like prostate cancer (CaP). PNP converts systemically administered prodrug, fludarabine phosphate, to a toxic metabolite, 2-fluoroadenine, that kills PNP-expressing and nearby cells by inhibiting DNA, RNA and protein synthesis. Reporter gene expression directed by a hybrid prostate-directed promoter and enhancer, PSMEPb, was assayed after plasmid transfection or viral transduction of prostate and non-CaP cell lines. Androgen-sensitive (AS) LNCaP-LN3 and androgen-independent (AI) PC3 human CaP xenografts in nude mice were injected intratumorally with an ovine atadenovirus vector, OAdV623, that carries the PNP gene under PSMEPb, formulated with cationic lipid for enhanced infectivity. Fludarabine phosphate was then given intraperitoneally for 5 days at 75 mg/m2/day. PNP expression was evaluated by enzymic conversion of its substrate using reverse phase HPLC. OAdV623 showed excellent in vitro transcriptional specificity for CaP cells. In vivo, expression of PNP persisted for > 6 days after OAdV623 injection and a single treatment provided 100% increase in tumor doubling time and > 50% inhibition of tumor growth for both LNCaP-LN3 and PC3 lines, with increased tumor necrosis and apoptosis and decreased tumor cell proliferation. OAdV623 significantly suppressed the growth of AS and AI human CaP xenografts in mice.
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Affiliation(s)
- X Y Wang
- Oncology Research Centre, Prince of Wales Hospital Clinical School of Medicine, The University of New South Wales, Randwick, Australia
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Silhár P, Pohl R, Votruba I, Hocek M. The first synthesis and cytostatic activity of novel 6-(fluoromethyl)purine bases and nucleosides. Org Biomol Chem 2005; 3:3001-7. [PMID: 16186932 DOI: 10.1039/b508122j] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two alternative approaches to the synthesis of novel 6-(fluoromethyl)purine bases and nucleosides are described either by direct deoxyfluorination or by multistep functional group transformations starting from 6-(hydroxymethyl)purines. 6-(fluoromethyl)purine ribonucleoside displayed significant cytostatic effects.
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Affiliation(s)
- Peter Silhár
- Centre for New Antivirals and Antineoplastics, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, CZ-16610, Prague 6, Czech Republic
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Arvidsson Y, Sumantran V, Watt F, Uramoto H, Funa K. Neuroblastoma-specific cytotoxicity mediated by the Mash1-promoter and E. coli purine nucleoside phosphorylase. Pediatr Blood Cancer 2005; 44:77-84. [PMID: 15390277 DOI: 10.1002/pbc.20163] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Neuroblastoma is derived from cells of neural crest origin and often expresses the transcription factor human achaete-scute homolog 1 (HASH1). The aim of this study was to selectively kill neuroblastoma cells by expressing the suicide gene E. coli purine nucleoside phosphorylase (PNP) under the control of the Mash1 promoter, the murine homolog of HASH1. PROCEDURE The E. coli PNP gene regulated by the Mash1 promoter was cloned into an expression vector and transfected into neuroblastoma and non-neuroblastoma cell lines. After addition of the prodrug M2-fluoroadenine 9-beta-D-arabinofuranoside (F-araA) the cell-specific toxicity was examined. To optimize the cell specific activity, different sizes of the Mash1 promoter were analyzed in neuroblastoma cell lines and compared with the activity in non-neuroblastoma cells. RESULTS Estimated as the percentages of CMV enhancer-promoter, the activity was significantly higher in the neuroblastoma cells, ranging from 17 to 58% when the shortest and the most active promoter was measured. The non-neuroblastoma cells yielded only 1-6% of the CMV promoter activity. When the shortest Mash1 promoter was combined with the E. coli PNP gene the cytotoxicity was 65% in the neuroblastoma cells with low cell death in the non-neuroblastoma cell lines, relative to the cytotoxicity where the E.coli PNP gene was regulated by the strong but non-specific CMV enhancer-promoter. CONCLUSIONS We show here that the Mash1 promoter regulating the PNP gene confers a cell-type selective toxicity in neuroblastoma cell lines. These results indicate the feasibility to use the Mash1 promoter for regulating E.coli PNP expression in gene-directed enzyme prodrug therapy (GDEPT) of neuroblastoma.
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Affiliation(s)
- Yvonne Arvidsson
- Department of Cell Biology, Institute of Anatomy and Cell Biology, Göteborg University, Gothenburg, Sweden.
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