1
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Holzinger T, Frei J, Jarzebska NT, Beer HD, Kündig TM, Pascolo S, Läuchli S, Mellett M. Differential functionality of fluoropyrimidine nucleosides for safe cancer therapy. Anticancer Drugs 2024:00001813-990000000-00306. [PMID: 39012759 DOI: 10.1097/cad.0000000000001644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Chemotherapies are standard care for most cancer types. Pyrimidine analogs including 5-fluorouracil, cytosine arabinoside, 5-azacytidine, and gemcitabine are effective drugs that are utilized as part of a number of anticancer regimens. However, their lack of cell-specificity results in severe side effects. Therefore, there is a capacity to improve the efficacy of such therapies, while decreasing unwanted side effects. Here, we report that while 5-fluorocytosine is not chemotherapeutic in itself, incorporated into a ribonucleoside and more importantly into an RNA oligonucleotide, it induces cytotoxic effects on cancer cells in vitro. Interestingly, these effects are rescued by both uridine and thymidine. Similarly, in-vitro 2'-deoxy-5-fluorocytidine inhibits the growth of tumor cells but has the advantage of being less toxic to human primary cells compared with 5-fluorocytidine, suggesting that the deoxyribonucleoside could exhibit less side-effects in vivo. Thus, this work indicates that the potency of 5-fluorocytidine and 2'-deoxy-5-fluorocytidine should be further explored. In particular, oligonucleotides incorporating 5-fluorocytosine could be novel chemotherapeutic drugs that could be formulated in cancer-specific particles for safe and efficacious cancer treatments.
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Affiliation(s)
- Tim Holzinger
- Department of Dermatology, University Hospital Zürich (USZ), University of Zürich (UZH)
- Faculty of Medicine
| | - Julia Frei
- Department of Dermatology, University Hospital Zürich (USZ), University of Zürich (UZH)
- Faculty of Medicine
| | - Natalia Teresa Jarzebska
- Department of Dermatology, University Hospital Zürich (USZ), University of Zürich (UZH)
- Faculty of Science, University of Zürich, Zürich, Switzerland
| | - Hans-Dietmar Beer
- Department of Dermatology, University Hospital Zürich (USZ), University of Zürich (UZH)
- Faculty of Medicine
| | - Thomas M Kündig
- Department of Dermatology, University Hospital Zürich (USZ), University of Zürich (UZH)
- Faculty of Medicine
| | - Steve Pascolo
- Department of Dermatology, University Hospital Zürich (USZ), University of Zürich (UZH)
- Faculty of Medicine
| | - Severin Läuchli
- Department of Dermatology, University Hospital Zürich (USZ), University of Zürich (UZH)
- Faculty of Medicine
| | - Mark Mellett
- Department of Dermatology, University Hospital Zürich (USZ), University of Zürich (UZH)
- Faculty of Medicine
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2
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Throll P, G Dolce L, Rico-Lastres P, Arnold K, Tengo L, Basu S, Kaiser S, Schneider R, Kowalinski E. Structural basis of tRNA recognition by the m 3C RNA methyltransferase METTL6 in complex with SerRS seryl-tRNA synthetase. Nat Struct Mol Biol 2024:10.1038/s41594-024-01341-3. [PMID: 38918637 DOI: 10.1038/s41594-024-01341-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 05/29/2024] [Indexed: 06/27/2024]
Abstract
Methylation of cytosine 32 in the anticodon loop of tRNAs to 3-methylcytosine (m3C) is crucial for cellular translation fidelity. Misregulation of the RNA methyltransferases setting this modification can cause aggressive cancers and metabolic disturbances. Here, we report the cryo-electron microscopy structure of the human m3C tRNA methyltransferase METTL6 in complex with seryl-tRNA synthetase (SerRS) and their common substrate tRNASer. Through the complex structure, we identify the tRNA-binding domain of METTL6. We show that SerRS acts as the tRNASer substrate selection factor for METTL6. We demonstrate that SerRS augments the methylation activity of METTL6 and that direct contacts between METTL6 and SerRS are necessary for efficient tRNASer methylation. Finally, on the basis of the structure of METTL6 in complex with SerRS and tRNASer, we postulate a universal tRNA-binding mode for m3C RNA methyltransferases, including METTL2 and METTL8, suggesting that these mammalian paralogs use similar ways to engage their respective tRNA substrates and cofactors.
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Affiliation(s)
| | | | - Palma Rico-Lastres
- Institute of Functional Epigenetics, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Katharina Arnold
- Institute of Functional Epigenetics, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Laura Tengo
- European Molecular Biology Laboratory, Grenoble, France
| | - Shibom Basu
- European Molecular Biology Laboratory, Grenoble, France
| | - Stefanie Kaiser
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Robert Schneider
- Institute of Functional Epigenetics, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Eva Kowalinski
- European Molecular Biology Laboratory, Grenoble, France.
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3
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Görlitz K, Bessler L, Helm M, Schaffrath R, Klassen R. Fluoropyrimidines trigger decay of hypomodified tRNA in yeast. Nucleic Acids Res 2024; 52:5841-5851. [PMID: 38716877 PMCID: PMC11162795 DOI: 10.1093/nar/gkae341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 04/10/2024] [Accepted: 04/22/2024] [Indexed: 06/11/2024] Open
Abstract
Therapeutic fluoropyrimidines 5-fluorouracil (5-FU) and 5-fluorocytosine (5-FC) are in long use for treatment of human cancers and severe invasive fungal infections, respectively. 5-Fluorouridine triphosphate represents a bioactive metabolite of both drugs and is incorporated into target cells' RNA. Here we use the model fungus Saccharomyces cerevisiae to define fluorinated tRNA as a key mediator of 5-FU and 5-FC cytotoxicity when specific tRNA methylations are absent. tRNA methylation deficiency caused by loss of Trm4 and Trm8 was previously shown to trigger an RNA quality control mechanism resulting in partial destabilization of hypomodified tRNAValAAC. We demonstrate that, following incorporation into tRNA, fluoropyrimidines strongly enhance degradation of yeast tRNAValAAC lacking Trm4 and Trm8 dependent methylations. At elevated temperature, such effect occurs already in absence of Trm8 alone. Genetic approaches and quantification of tRNA modification levels reveal that enhanced fluoropyrimidine cytotoxicity results from additional, drug induced uridine modification loss and activation of tRNAValAAC decay involving the exonuclease Xrn1. These results suggest that inhibition of tRNA methylation may be exploited to boost therapeutic efficiency of 5-FU and 5-FC.
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Affiliation(s)
- Katharina Görlitz
- Institute of Biology, Department of Microbiology, Universität Kassel, Kassel 34132, Germany
| | - Larissa Bessler
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - Mark Helm
- Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-Universität Mainz, Mainz 55128, Germany
| | - Raffael Schaffrath
- Institute of Biology, Department of Microbiology, Universität Kassel, Kassel 34132, Germany
| | - Roland Klassen
- Institute of Biology, Department of Microbiology, Universität Kassel, Kassel 34132, Germany
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4
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De Zoysa T, Hauke AC, Iyer NR, Marcus E, Ostrowski SM, Stegemann F, Ermolenko DN, Fay JC, Phizicky EM. A connection between the ribosome and two S. pombe tRNA modification mutants subject to rapid tRNA decay. PLoS Genet 2024; 20:e1011146. [PMID: 38295128 PMCID: PMC10861057 DOI: 10.1371/journal.pgen.1011146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 02/12/2024] [Accepted: 01/22/2024] [Indexed: 02/02/2024] Open
Abstract
tRNA modifications are crucial in all organisms to ensure tRNA folding and stability, and accurate translation. In both the yeast Saccharomyces cerevisiae and the evolutionarily distant yeast Schizosaccharomyces pombe, mutants lacking certain tRNA body modifications (outside the anticodon loop) are temperature sensitive due to rapid tRNA decay (RTD) of a subset of hypomodified tRNAs. Here we show that for each of two S. pombe mutants subject to RTD, mutations in ribosomal protein genes suppress the temperature sensitivity without altering tRNA levels. Prior work showed that S. pombe trm8Δ mutants, lacking 7-methylguanosine, were temperature sensitive due to RTD, and that one class of suppressors had mutations in the general amino acid control (GAAC) pathway, which was activated concomitant with RTD, resulting in further tRNA loss. We now find that another class of S. pombe trm8Δ suppressors have mutations in rpl genes, encoding 60S subunit proteins, and that suppression occurs with minimal restoration of tRNA levels and reduced GAAC activation. Furthermore, trm8Δ suppression extends to other mutations in the large or small ribosomal subunit. We also find that S. pombe tan1Δ mutants, lacking 4-acetylcytidine, are temperature sensitive due to RTD, that one class of suppressors have rpl mutations, associated with minimal restoration of tRNA levels, and that suppression extends to other rpl and rps mutations. However, although S. pombe tan1Δ temperature sensitivity is associated with some GAAC activation, suppression by an rpl mutation only modestly inhibits GAAC activation. We propose a model in which ribosomal protein mutations result in reduced ribosome concentrations, leading to both reduced ribosome collisions and a reduced requirement for tRNA, with these effects having different relative importance in trm8Δ and tan1Δ mutants. This model is consistent with our results in S. cerevisiae trm8Δ trm4Δ mutants, known to undergo RTD, fueling speculation that this model applies across eukaryotes.
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Affiliation(s)
- Thareendra De Zoysa
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Alayna C. Hauke
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Nivedita R. Iyer
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Erin Marcus
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Sarah M. Ostrowski
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Franziska Stegemann
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Dmitri N. Ermolenko
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Justin C. Fay
- Department of Biology, University of Rochester, Rochester, New York, United States of America
| | - Eric M. Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York, United States of America
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5
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De Zoysa T, Hauke AC, Iyer NR, Marcus E, Ostrowski SM, Fay JC, Phizicky EM. A connection between the ribosome and two S. pombe tRNA modification mutants subject to rapid tRNA decay. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.18.558340. [PMID: 37790432 PMCID: PMC10542129 DOI: 10.1101/2023.09.18.558340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
tRNA modifications are crucial in all organisms to ensure tRNA folding and stability, and accurate translation in the ribosome. In both the yeast Saccharomyces cerevisiae and the evolutionarily distant yeast Schizosaccharomyces pombe, mutants lacking certain tRNA body modifications (outside the anticodon loop) are temperature sensitive due to rapid tRNA decay (RTD) of a subset of hypomodified tRNAs. Here we show that for each of two S. pombe mutants subject to RTD, mutations in ribosomal protein genes suppress the temperature sensitivity without altering tRNA levels. Prior work showed that S. pombe trm8Δ mutants, lacking 7-methylguanosine, were temperature sensitive due to RTD and that one class of suppressors had mutations in the general amino acid control (GAAC) pathway, which was activated concomitant with RTD, resulting in further tRNA loss. We now find that another class of S. pombe trm8Δ suppressors have mutations in rpl genes, encoding 60S subunit proteins, and that suppression occurs with minimal restoration of tRNA levels and reduced GAAC activation. Furthermore, trm8Δ suppression extends to other mutations in the large or small ribosomal subunit. We also find that S. pombe tan1Δ mutants, lacking 4-acetylcytidine, are temperature sensitive due to RTD, that one class of suppressors have rpl mutations, associated with minimal restoration of tRNA levels, and that suppression extends to other rpl and rps mutations. However, although S. pombe tan1Δ temperature sensitivity is associated with some GAAC activation, suppression by an rpl mutation does not significantly inhibit GAAC activation. These results suggest that ribosomal protein mutations suppress the temperature sensitivity of S. pombe trm8Δ and tan1Δ mutants due to reduced ribosome concentrations, leading to both a reduced requirement for tRNA, and reduced ribosome collisions and GAAC activation. Results with S. cerevisiae trm8Δ trm4Δ mutants are consistent with this model, and fuel speculation that similar results will apply across eukaryotes.
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Affiliation(s)
- Thareendra De Zoysa
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Alayna C. Hauke
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Nivedita R. Iyer
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Erin Marcus
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Sarah M. Ostrowski
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
| | - Justin C. Fay
- Department of Biology, University of Rochester, Rochester, NY, USA 14627
| | - Eric M. Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, USA 14642
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6
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Asadi MR, Moslehian MS, Sabaie H, Poornabi M, Ghasemi E, Hassani M, Hussen BM, Taheri M, Rezazadeh M. Stress Granules in the Anti-Cancer Medications Mechanism of Action: A Systematic Scoping Review. Front Oncol 2021; 11:797549. [PMID: 35004322 PMCID: PMC8739770 DOI: 10.3389/fonc.2021.797549] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/08/2021] [Indexed: 12/16/2022] Open
Abstract
Stress granule (SG) formation is a well-known cellular mechanism for minimizing stress-related damage and increasing cell survival. In addition to playing a critical role in the stress response, SGs have emerged as critical mediators in human health. It seems logical that SGs play a key role in cancer cell formation, development, and metastasis. Recent studies have shown that many SG components contribute to the anti-cancer medications' responses through tumor-associated signaling pathways and other mechanisms. SG proteins are known for their involvement in the translation process, control of mRNA stability, and capacity to function in both the cytoplasm and nucleus. The current systematic review aimed to include all research on the impact of SGs on the mechanism of action of anti-cancer medications and was conducted using a six-stage methodological framework and the PRISMA guideline. Prior to October 2021, a systematic search of seven databases for eligible articles was performed. Following the review of the publications, the collected data were subjected to quantitative and qualitative analysis. Notably, Bortezomib, Sorafenib, Oxaliplatin, 5-fluorouracil, Cisplatin, and Doxorubicin accounted for the majority of the medications examined in the studies. Overall, this systematic scoping review attempts to demonstrate and give a complete overview of the function of SGs in the mechanism of action of anti-cancer medications by evaluating all research.
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Affiliation(s)
- Mohammad Reza Asadi
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Hani Sabaie
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Marziye Poornabi
- Student Research Committee, School of Medicine, Shahroud University of Medical Science, Shahroud, Iran
| | - Elham Ghasemi
- Department of Molecular Medicine and Biotechnology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran
| | - Mehdi Hassani
- Student Research Committee, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Bashdar Mahmud Hussen
- Department of Pharmacognosy, College of Pharmacy, Hawler Medical University, Erbil, Iraq
| | - Mohammad Taheri
- Skull Base Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Institute of Human Genetics, Jena University Hospital, Jena, Germany
| | - Maryam Rezazadeh
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
- Clinical Research Development Unit of Tabriz Valiasr Hospital, Tabriz University of Medical Sciences, Tabriz, Iran
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7
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Wollen KL, Hagen L, Vågbø CB, Rabe R, Iveland TS, Aas PA, Sharma A, Sporsheim B, Erlandsen HO, Palibrk V, Bjørås M, Fonseca DM, Mosammaparast N, Slupphaug G. ALKBH3 partner ASCC3 mediates P-body formation and selective clearance of MMS-induced 1-methyladenosine and 3-methylcytosine from mRNA. J Transl Med 2021; 19:287. [PMID: 34217309 PMCID: PMC8254245 DOI: 10.1186/s12967-021-02948-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 06/17/2021] [Indexed: 02/07/2023] Open
Abstract
Background Reversible enzymatic methylation of mammalian mRNA is widespread and serves crucial regulatory functions, but little is known to what degree chemical alkylators mediate overlapping modifications and whether cells distinguish aberrant from canonical methylations. Methods Here we use quantitative mass spectrometry to determine the fate of chemically induced methylbases in the mRNA of human cells. Concomitant alteration in the mRNA binding proteome was analyzed by SILAC mass spectrometry. Results MMS induced prominent direct mRNA methylations that were chemically identical to endogenous methylbases. Transient loss of 40S ribosomal proteins from isolated mRNA suggests that aberrant methylbases mediate arrested translational initiation and potentially also no-go decay of the affected mRNA. Four proteins (ASCC3, YTHDC2, TRIM25 and GEMIN5) displayed increased mRNA binding after MMS treatment. ASCC3 is a binding partner of the DNA/RNA demethylase ALKBH3 and was recently shown to promote disassembly of collided ribosomes as part of the ribosome quality control (RQC) trigger complex. We find that ASCC3-deficient cells display delayed removal of MMS-induced 1-methyladenosine (m1A) and 3-methylcytosine (m3C) from mRNA and impaired formation of MMS-induced P-bodies. Conclusions Our findings conform to a model in which ASCC3-mediated disassembly of collided ribosomes allows demethylation of aberrant m1A and m3C by ALKBH3. Our findings constitute first evidence of selective sanitation of aberrant mRNA methylbases over their endogenous counterparts and warrant further studies on RNA-mediated effects of chemical alkylators commonly used in the clinic. Supplementary Information The online version contains supplementary material available at 10.1186/s12967-021-02948-6.
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Affiliation(s)
- Kristian Lied Wollen
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim, Norway
| | - Lars Hagen
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim, Norway.,PROMEC Core Facility for Proteomics and Modomics, Norwegian University of Science and Technology, NTNU, and the Central Norway Regional Health Authority Norway, Trondheim, Norway
| | - Cathrine B Vågbø
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim, Norway.,PROMEC Core Facility for Proteomics and Modomics, Norwegian University of Science and Technology, NTNU, and the Central Norway Regional Health Authority Norway, Trondheim, Norway
| | - Renana Rabe
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim, Norway
| | - Tobias S Iveland
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim, Norway
| | - Per Arne Aas
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim, Norway
| | - Animesh Sharma
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim, Norway.,PROMEC Core Facility for Proteomics and Modomics, Norwegian University of Science and Technology, NTNU, and the Central Norway Regional Health Authority Norway, Trondheim, Norway
| | - Bjørnar Sporsheim
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.,CMIC Cellular & Molecular Imaging Core Facility, Norwegian University of Science and Technology, NTNU, and the Central Norway Regional Health Authority Norway, Trondheim, Norway
| | - Hilde O Erlandsen
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway
| | - Vuk Palibrk
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway
| | - Magnar Bjørås
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway
| | - Davi M Fonseca
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim, Norway.,PROMEC Core Facility for Proteomics and Modomics, Norwegian University of Science and Technology, NTNU, and the Central Norway Regional Health Authority Norway, Trondheim, Norway
| | - Nima Mosammaparast
- Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Geir Slupphaug
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway. .,Clinic of Laboratory Medicine, St. Olavs Hospital, Trondheim, Norway. .,PROMEC Core Facility for Proteomics and Modomics, Norwegian University of Science and Technology, NTNU, and the Central Norway Regional Health Authority Norway, Trondheim, Norway.
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8
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Kanno Y, Chen CY, Lee HL, Chiou JF, Chen YJ. Molecular Mechanisms of Chemotherapy Resistance in Head and Neck Cancers. Front Oncol 2021; 11:640392. [PMID: 34026617 PMCID: PMC8138159 DOI: 10.3389/fonc.2021.640392] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/06/2021] [Indexed: 12/24/2022] Open
Abstract
Chemotherapy resistance is a huge barrier for head and neck cancer (HNC) patients and therefore requires close attention to understand its underlay mechanisms for effective strategies. In this review, we first summarize the molecular mechanisms of chemotherapy resistance that occur during the treatment with cisplatin, 5-fluorouracil, and docetaxel/paclitaxel, including DNA/RNA damage repair, drug efflux, apoptosis inhibition, and epidermal growth factor receptor/focal adhesion kinase/nuclear factor-κB activation. Next, we describe the potential approaches to combining conventional therapies with previous cancer treatments such as immunotherapy, which may improve the treatment outcomes and prolong the survival of HNC patients. Overall, by parsing the reported molecular mechanisms of chemotherapy resistance within HNC patient’s tumors, we can improve the prediction of chemotherapeutic responsiveness, and reveal new therapeutic targets for the future.
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Affiliation(s)
- Yuzuka Kanno
- Division of Molecular Regulation of Inflammatory and Immune Disease, Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba, Japan.,Department of Medicinal and Life Sciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan
| | - Chang-Yu Chen
- Division of Molecular Regulation of Inflammatory and Immune Disease, Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba, Japan.,Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hsin-Lun Lee
- Department of Radiation Oncology, Taipei Medical University Hospital, Taipei, Taiwan.,Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.,Taipei Cancer Center, Taipei Medical University, Taipei, Taiwan
| | - Jeng-Fong Chiou
- Department of Radiation Oncology, Taipei Medical University Hospital, Taipei, Taiwan.,Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.,Taipei Cancer Center, Taipei Medical University, Taipei, Taiwan.,TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yin-Ju Chen
- Department of Radiation Oncology, Taipei Medical University Hospital, Taipei, Taiwan.,TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei, Taiwan.,Graduate Institute of Biomedical Materials and Tissue Engineering, College of Biomedical Engineering, Taipei Medical University, Taipei, Taiwan.,International PhD Program in Biomedical Engineering, College of Biomedical Engineering, Taipei Medical University, Taipei, Taiwan.,Translational Laboratory, Research Department, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan
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9
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Yu QK, Han LT, Wu YJ, Liu TB. The Role of Oxidoreductase-Like Protein Olp1 in Sexual Reproduction and Virulence of Cryptococcus neoformans. Microorganisms 2020; 8:microorganisms8111730. [PMID: 33158259 PMCID: PMC7694259 DOI: 10.3390/microorganisms8111730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 10/31/2020] [Accepted: 11/03/2020] [Indexed: 11/16/2022] Open
Abstract
Cryptococcus neoformans is a basidiomycete human fungal pathogen causing lethal meningoencephalitis, mainly in immunocompromised patients. Oxidoreductases are a class of enzymes that catalyze redox, playing a crucial role in biochemical reactions. In this study, we identified one Cryptococcus oxidoreductase-like protein-encoding gene OLP1 and investigated its role in the sexual reproduction and virulence of C. neoformans. Gene expression patterns analysis showed that the OLP1 gene was expressed in each developmental stage of Cryptococcus, and the Olp1 protein was located in the cytoplasm of Cryptococcus cells. Although it produced normal major virulence factors such as melanin and capsule, the olp1Δ mutants showed growth defects on the yeast extract peptone dextrose (YPD) medium supplemented with lithium chloride (LiCl) and 5-fluorocytosine (5-FC). The fungal mating analysis showed that Olp1 is also essential for fungal sexual reproduction, as olp1Δ mutants show significant defects in hyphae growth and basidiospores production during bisexual reproduction. The fungal nuclei imaging showed that during the bilateral mating of olp1Δ mutants, the nuclei failed to undergo meiosis after fusion in the basidia, indicating that Olp1 is crucial for regulating meiosis during mating. Moreover, Olp1 was also found to be required for fungal virulence in C. neoformans, as the olp1Δ mutants showed significant virulence attenuation in a murine inhalation model. In conclusion, our results showed that the oxidoreductase-like protein Olp1 is required for both fungal sexual reproduction and virulence in C. neoformans.
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Affiliation(s)
- Qi-Kun Yu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (Q.-K.Y.); (L.-T.H.); (Y.-J.W.)
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
| | - Lian-Tao Han
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (Q.-K.Y.); (L.-T.H.); (Y.-J.W.)
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
| | - Yu-Juan Wu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (Q.-K.Y.); (L.-T.H.); (Y.-J.W.)
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
| | - Tong-Bao Liu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (Q.-K.Y.); (L.-T.H.); (Y.-J.W.)
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
- Correspondence: ; Tel.: +86-23-6825-1088
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10
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Keffer-Wilkes LC, Soon EF, Kothe U. The methyltransferase TrmA facilitates tRNA folding through interaction with its RNA-binding domain. Nucleic Acids Res 2020; 48:7981-7990. [PMID: 32597953 PMCID: PMC7641329 DOI: 10.1093/nar/gkaa548] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 05/29/2020] [Accepted: 06/17/2020] [Indexed: 11/12/2022] Open
Abstract
tRNAs are the most highly modified RNAs in all cells, and formation of 5-methyluridine (m5U) at position 54 in the T arm is a common RNA modification found in all tRNAs. The m5U modification is generated by the methyltransferase TrmA. Here, we test and prove the hypothesis that Escherichia coli TrmA has dual functions, acting both as a methyltransferase and as a tRNA chaperone. We identify two conserved residues, F106 and H125, in the RNA-binding domain of TrmA, which interact with the tRNA elbow and are critical for tRNA binding. Co-culture competition assays reveal that the catalytic activity of TrmA is important for cellular fitness, and that substitutions of F106 or H125 impair cellular fitness. We directly show that TrmA enhances tRNA folding in vitro independent of its catalytic activity. In conclusion, our study suggests that F106 and H125 in the RNA-binding domain of TrmA act as a wedge disrupting tertiary interactions between tRNA’s D arm and T arm; this tRNA unfolding is the mechanistic basis for TrmA’s tRNA chaperone activity. TrmA is the second tRNA modifying enzyme next to the pseudouridine synthase TruB shown to act as a tRNA chaperone supporting a functional link between RNA modification and folding.
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Affiliation(s)
- Laura Carole Keffer-Wilkes
- University of Lethbridge, Alberta RNA Research and Training Institute (ARRTI), Department of Chemistry and Biochemistry, Lethbridge, AB T1K 3M4, Canada
| | - Emily F Soon
- University of Lethbridge, Alberta RNA Research and Training Institute (ARRTI), Department of Chemistry and Biochemistry, Lethbridge, AB T1K 3M4, Canada
| | - Ute Kothe
- University of Lethbridge, Alberta RNA Research and Training Institute (ARRTI), Department of Chemistry and Biochemistry, Lethbridge, AB T1K 3M4, Canada
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11
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De Zoysa T, Phizicky EM. Hypomodified tRNA in evolutionarily distant yeasts can trigger rapid tRNA decay to activate the general amino acid control response, but with different consequences. PLoS Genet 2020; 16:e1008893. [PMID: 32841241 PMCID: PMC7473580 DOI: 10.1371/journal.pgen.1008893] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 09/04/2020] [Accepted: 07/22/2020] [Indexed: 12/14/2022] Open
Abstract
All tRNAs are extensively modified, and modification deficiency often results in growth defects in the budding yeast Saccharomyces cerevisiae and neurological or other disorders in humans. In S. cerevisiae, lack of any of several tRNA body modifications results in rapid tRNA decay (RTD) of certain mature tRNAs by the 5'-3' exonucleases Rat1 and Xrn1. As tRNA quality control decay mechanisms are not extensively studied in other eukaryotes, we studied trm8Δ mutants in the evolutionarily distant fission yeast Schizosaccharomyces pombe, which lack 7-methylguanosine at G46 (m7G46) of their tRNAs. We report here that S. pombe trm8Δ mutants are temperature sensitive primarily due to decay of tRNATyr(GUA) and that spontaneous mutations in the RAT1 ortholog dhp1+ restored temperature resistance and prevented tRNA decay, demonstrating conservation of the RTD pathway. We also report for the first time evidence linking the RTD and the general amino acid control (GAAC) pathways, which we show in both S. pombe and S. cerevisiae. In S. pombe trm8Δ mutants, spontaneous GAAC mutations restored temperature resistance and tRNA levels, and the trm8Δ temperature sensitivity was precisely linked to GAAC activation due to tRNATyr(GUA) decay. Similarly, in the well-studied S. cerevisiae trm8Δ trm4Δ RTD mutant, temperature sensitivity was closely linked to GAAC activation due to tRNAVal(AAC) decay; however, in S. cerevisiae, GAAC mutations increased tRNA loss and exacerbated temperature sensitivity. A similar exacerbated growth defect occurred upon GAAC mutation in S. cerevisiae trm8Δ and other single modification mutants that triggered RTD. Thus, these results demonstrate a conserved GAAC activation coincident with RTD in S. pombe and S. cerevisiae, but an opposite impact of the GAAC response in the two organisms. We speculate that the RTD pathway and its regulation of the GAAC pathway is widely conserved in eukaryotes, extending to other mutants affecting tRNA body modifications.
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Affiliation(s)
- Thareendra De Zoysa
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, United States of America
| | - Eric M. Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, United States of America
- * E-mail:
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12
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Carter JM, Emmett W, Mozos IR, Kotter A, Helm M, Ule J, Hussain S. FICC-Seq: a method for enzyme-specified profiling of methyl-5-uridine in cellular RNA. Nucleic Acids Res 2019; 47:e113. [PMID: 31361898 PMCID: PMC6821191 DOI: 10.1093/nar/gkz658] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 07/03/2019] [Accepted: 07/17/2019] [Indexed: 12/16/2022] Open
Abstract
Methyl-5-uridine (m5U) is one the most abundant non-canonical bases present in cellular RNA, and in yeast is found at position U54 of tRNAs where modification is catalysed by the methyltransferase Trm2. Although the mammalian enzymes that catalyse m5U formation are yet to be identified via experimental evidence, based on sequence homology to Trm2, two candidates currently exist, TRMT2A and TRMT2B. Here we developed a genome-wide single-nucleotide resolution mapping method, Fluorouracil-Induced-Catalytic-Crosslinking-Sequencing (FICC-Seq), in order to identify the relevant enzymatic targets. We demonstrate that TRMT2A is responsible for the majority of m5U present in human RNA, and that it commonly targets U54 of cytosolic tRNAs. By comparison to current methods, we show that FICC-Seq is a particularly robust method for accurate and reliable detection of relevant enzymatic target sites. Our associated finding of extensive irreversible TRMT2A-tRNA crosslinking in vivo following 5-Fluorouracil exposure is also intriguing, as it suggests a tangible mechanism for a previously suspected RNA-dependent route of Fluorouracil-mediated cytotoxicity.
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Affiliation(s)
- Jean-Michel Carter
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Warren Emmett
- The Francis-Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,University College London Genetics Institute, Gower Street, London, WC1E 6BT, UK
| | - Igor Rdl Mozos
- The Francis-Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,Department for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Annika Kotter
- Johannes Gutenberg-Universität, Institut für Pharmazie und Biochemie, Staudinger Weg 5, 55128 Mainz, Germany
| | - Mark Helm
- Johannes Gutenberg-Universität, Institut für Pharmazie und Biochemie, Staudinger Weg 5, 55128 Mainz, Germany
| | - Jernej Ule
- The Francis-Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,Department for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Shobbir Hussain
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
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13
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Sharma V, Gupta SK, Verma M. Dihydropyrimidine dehydrogenase in the metabolism of the anticancer drugs. Cancer Chemother Pharmacol 2019; 84:1157-1166. [DOI: 10.1007/s00280-019-03936-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 08/21/2019] [Indexed: 01/02/2023]
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14
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Catalytic crosslinking-based methods for enzyme-specified profiling of RNA ribonucleotide modifications. Methods 2018; 156:60-65. [PMID: 30308313 DOI: 10.1016/j.ymeth.2018.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/23/2018] [Accepted: 10/05/2018] [Indexed: 12/26/2022] Open
Abstract
Well over a hundred types of naturally occurring covalent modifications can be made to ribonucleotides in RNA molecules. Moreover, several types of such modifications are each known to be catalysed by multiple enzymes which largely appear to modify distinct sites within the cellular RNA. In order to aid functional investigations of such multi-enzyme RNA modification types in particular, it is important to determine which enzyme is responsible for catalysing modification at each site. Two methods, Aza-IP and methylation-iCLIP, were developed and used to map genome-wide locations of methyl-5-cytosine (m5C) RNA modifications inherently in an enzyme specific context. Though the methods are quite distinct, both rely on capturing catalytic intermediates of RNA m5C methyltransferases in a state where the cytosine undergoing methylation is covalently crosslinked to the enzyme. More recently the fundamental methylation-iCLIP principle has also been applied to map methyl-2-adenosine sites catalysed by the E. coli RlmN methylsynthase. Here I describe the ideas on which the two basic methods hinge, and summarise what has been achieved by them thus far. I also discuss whether and how such principles may be further exploited for profiling of other RNA modification types, such as methyl-5-uridine and pseudouridine.
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15
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Jorge AF, Aviñó A, Pais AACC, Eritja R, Fàbrega C. DNA-based nanoscaffolds as vehicles for 5-fluoro-2'-deoxyuridine oligomers in colorectal cancer therapy. NANOSCALE 2018; 10:7238-7249. [PMID: 29632908 DOI: 10.1039/c7nr08442k] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Fluoropyrimidines, such as 5-fluorouracil (5-FU) and related prodrugs, are considered one of the most successful agents in the treatment of colorectal cancer, yet poor specificity and tumor cell resistance remain the major limiting bottlenecks. Here, we exploited for the first time the ability of two DNA nanoscaffolds, a DNA tetrahedron (Td) and rectangle DNA origami, to incorporate 5-fluoro-2'-deoxyuridine (FdUn) oligomers. In addition, cholesterol moieties were synthetically attached to Td and DNA origami staples to enhance cellular uptake. DNA nanostructures functionalized with FdUn exhibited an enhanced cytotoxicity and higher ability to trigger apoptosis in colorectal cancer cells relative to conventional 5-FU and FdU, especially having cholesterol as an internalization helper. The cholesterol content mostly correlates with the increase of the FdUn nanostructure cytotoxicity. DNA nanoscaffolds bearing FdUn were able to circumvent the low sensitivity of colorectal cancer cells towards 5-FU. Both DNA nanostructures attained a comparable cytotoxic effect yet Td displays higher antiproliferative action. The ability to reduce the proliferation of cancer cells is mainly related to the concentration of DNA nanostructures. The present work suggests that self-assembled DNA nanoparticles are privileged vehicles for delivering fluoropyrimidines, opening new avenues to the development of promising therapeutics for cancer treatment.
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Affiliation(s)
- A F Jorge
- Coimbra Chemistry Centre (CQC), Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal.
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16
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5-Fluorouracil targets thymidylate synthase in the selective suppression of TH17 cell differentiation. Oncotarget 2017; 7:19312-26. [PMID: 27027355 PMCID: PMC4991385 DOI: 10.18632/oncotarget.8344] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/07/2016] [Indexed: 12/02/2022] Open
Abstract
While it is well established that treatment of cancer patients with 5-Fluorouracil (5-FU) can result in immune suppression, the exact function of 5-FU in the modulation of immune cells has not been fully established. We found that low dose 5-FU selectively suppresses TH17 and TH1 cell differentiation without apparent effect on Treg, TH2, and significantly suppresses thymidylate synthase (TS) expression in TH17 and TH1 cells but has a lesser effect in tumor cells and macrophages. Interestingly, the basal expression of TS varies significantly between T helper phenotypes and knockdown of TS significantly impairs TH17 and TH1 cell differentiation without affecting the differentiation of either Treg or TH2 cells. Finally, low dose 5-FU is effective in ameliorating colitis development by suppressing TH17 and TH1 cell development in a T cell transfer colitis model. Taken together, the results highlight the importance of the anti-inflammatory functions of low dose 5-FU by selectively suppressing TH17 and TH1 immune responses.
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17
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Shamim HM, Minami Y, Tanaka D, Ukimori S, Murray JM, Ueno M. Fission yeast strains with circular chromosomes require the 9-1-1 checkpoint complex for the viability in response to the anti-cancer drug 5-fluorodeoxyuridine. PLoS One 2017; 12:e0187775. [PMID: 29121084 PMCID: PMC5679574 DOI: 10.1371/journal.pone.0187775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 10/25/2017] [Indexed: 11/18/2022] Open
Abstract
Thymidine kinase converts 5-fluorodeoxyuridine to 5-fluorodeoxyuridine monophosphate, which causes disruption of deoxynucleotide triphosphate ratios. The fission yeast Schizosaccharomyces pombe does not express endogenous thymidine kinase but 5-fluorodeoxyuridine inhibits growth when exogenous thymidine kinase is expressed. Unexpectedly, we found that 5-fluorodeoxyuridine causes S phase arrest even without thymidine kinase expression. DNA damage checkpoint proteins such as the 9-1-1 complex were required for viability in the presence of 5-fluorodeoxyuridine. We also found that strains with circular chromosomes, due to loss of pot1+, which have higher levels of replication stress, were more sensitive to loss of the 9-1-1 complex in the presence of 5-fluorodeoxyuridine. Thus, our results suggest that strains carrying circular chromosomes exhibit a greater dependence on DNA damage checkpoints to ensure viability in the presence of 5-fluorodeoxyuridine compared to stains that have linear chromosomes.
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Affiliation(s)
- Hossain Mohammad Shamim
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Yukako Minami
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Daiki Tanaka
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Shinobu Ukimori
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Johanne M. Murray
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Masaru Ueno
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
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18
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Motorin Y, Seidu-Larry S, Helm M. DNA and RNA Pyrimidine Nucleobase Alkylation at the Carbon-5 Position. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 945:19-33. [PMID: 27826833 DOI: 10.1007/978-3-319-43624-1_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The carbon 5 of pyrimidine nucleobases is a privileged position in terms of nucleoside modification in both DNA and RNA. The simplest modification of uridine at this position is methylation leading to thymine. Thymine is an integral part of the standard nucleobase repertoire of DNA that is synthesized at the nucleotide level. However, it also occurs in RNA, where it is synthesized posttranscriptionally at the polynucleotide level. The cytidine analogue 5-methylcytidine also occurs in both DNA and RNA, but is introduced at the polynucleotide level in both cases. The same applies to a plethora of additional derivatives found in nature, resulting either from a direct modification of the 5-position by electrophiles or by further derivatization of the 5-methylpyrimidines. Here, we review the structural diversity of these modified bases, the variety of cofactors that serve as carbon donors, and the common principles shared by enzymatic mechanisms generating them.
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Affiliation(s)
- Yuri Motorin
- IMoPA UMR7365 CNRS-UL, BioPole de l'Université de Lorraine, 9 avenue de la Foret de Haye, 54505, Vandoeuvre-les-Nancy, France.
| | - Salifu Seidu-Larry
- Department of Biochemistry, University of Cape Coast, College of Agriculture and Natural Sciences, School of Biological Sciences, Cape Coast, Ghana
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Staudingerweg 5, 55128, Mainz, Germany
| | - Mark Helm
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Staudingerweg 5, 55128, Mainz, Germany.
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19
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Fitzsimmons CM, Fujimori DG. Determinants of tRNA Recognition by the Radical SAM Enzyme RlmN. PLoS One 2016; 11:e0167298. [PMID: 27902775 PMCID: PMC5130265 DOI: 10.1371/journal.pone.0167298] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/12/2016] [Indexed: 11/19/2022] Open
Abstract
RlmN, a bacterial radical SAM methylating enzyme, has the unusual ability to modify two distinct types of RNA: 23S rRNA and tRNA. In rRNA, RlmN installs a methyl group at the C2 position of A2503 of 23S rRNA, while in tRNA the modification occurs at nucleotide A37, immediately adjacent to the anticodon triplet. Intriguingly, only a subset of tRNAs that contain an adenosine at position 37 are substrates for RlmN, suggesting that the enzyme carefully probes the highly conserved tRNA fold and sequence features to identify its targets. Over the past several years, multiple studies have addressed rRNA modification by RlmN, while relatively few investigations have focused on the ability of this enzyme to modify tRNAs. In this study, we utilized in vitro transcribed tRNAs as model substrates to interrogate RNA recognition by RlmN. Using chimeras and point mutations, we probed how the structure and sequence of RNA influences methylation, identifying position 38 of tRNAs as a critical determinant of substrate recognition. We further demonstrate that, analogous to previous mechanistic studies with fragments of 23S rRNA, tRNA methylation requirements are consistent with radical SAM reactivity. Together, our findings provide detailed insight into tRNA recognition by a radical SAM methylating enzyme.
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Affiliation(s)
- Christina M. Fitzsimmons
- Chemistry and Chemical Biology Graduate Program, University of California San Francisco, San Francisco, California, United States of America
| | - Danica Galonić Fujimori
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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20
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Shelton J, Lu X, Hollenbaugh JA, Cho JH, Amblard F, Schinazi RF. Metabolism, Biochemical Actions, and Chemical Synthesis of Anticancer Nucleosides, Nucleotides, and Base Analogs. Chem Rev 2016; 116:14379-14455. [PMID: 27960273 DOI: 10.1021/acs.chemrev.6b00209] [Citation(s) in RCA: 235] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Nucleoside, nucleotide, and base analogs have been in the clinic for decades to treat both viral pathogens and neoplasms. More than 20% of patients on anticancer chemotherapy have been treated with one or more of these analogs. This review focuses on the chemical synthesis and biology of anticancer nucleoside, nucleotide, and base analogs that are FDA-approved and in clinical development since 2000. We highlight the cellular biology and clinical biology of analogs, drug resistance mechanisms, and compound specificity towards different cancer types. Furthermore, we explore analog syntheses as well as improved and scale-up syntheses. We conclude with a discussion on what might lie ahead for medicinal chemists, biologists, and physicians as they try to improve analog efficacy through prodrug strategies and drug combinations.
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Affiliation(s)
- Jadd Shelton
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine , 1760 Haygood Drive, NE, Atlanta, Georgia 30322, United States
| | - Xiao Lu
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine , 1760 Haygood Drive, NE, Atlanta, Georgia 30322, United States
| | - Joseph A Hollenbaugh
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine , 1760 Haygood Drive, NE, Atlanta, Georgia 30322, United States
| | - Jong Hyun Cho
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine , 1760 Haygood Drive, NE, Atlanta, Georgia 30322, United States
| | - Franck Amblard
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine , 1760 Haygood Drive, NE, Atlanta, Georgia 30322, United States
| | - Raymond F Schinazi
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine , 1760 Haygood Drive, NE, Atlanta, Georgia 30322, United States
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21
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Negrei C, Hudita A, Ginghina O, Galateanu B, Voicu SN, Stan M, Costache M, Fenga C, Drakoulis N, Tsatsakis AM. Colon Cancer Cells Gene Expression Signature As Response to 5- Fluorouracil, Oxaliplatin, and Folinic Acid Treatment. Front Pharmacol 2016; 7:172. [PMID: 27445811 PMCID: PMC4917556 DOI: 10.3389/fphar.2016.00172] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 06/03/2016] [Indexed: 12/05/2022] Open
Abstract
5-FU cytotoxicity mechanism has been assigned both to the miss-incorporation of fluoronucleotides into RNA and DNA and to the inhibition of thymidylate synthase. 5-FU is one of the most widely used chemotherapeutic drugs, although it has severe side effects that may vary between patients. Pharmacogenetic studies related to 5-FU have been traditionally focused on the rate-limiting catabolic enzyme, dihydropyrimidine dehydrogenase that breaks 80–85% of 5-FU into its inactive metabolite. Choosing the right dosing scheme and chemotherapy strategy for each individual patient remains challenging for personalized chemotherapy management. In the general effort toward reduction of colorectal cancer mortality, in vitro screening studies play a very important role. To accelerate translation research, increasing interest has been focused on using in vivo-like models such as three-dimensional spheroids. The development of higher throughput assays to quantify phenotypic changes in spheroids is an active research area. Consequently, in this study we used the microarray technology to reveal the HT-29 colorectal adenocarcinoma cells gene expression signature as response to 5-FU/OXP/FA treatment in a state of the art 3D culture system. We report here an increased reactive oxygen species production under treatment, correlated with a decrease in cell viability and proliferation potential. With respect to the HT-29 cells gene expression under the treatment with 5-FU/OXP/FA, we found 15.247 genes that were significantly differentially expressed (p < 0.05) with a fold change higher that two-fold. Among these, 7136 genes were upregulated and 8111 genes were downregulated under experimental conditions as compared to untreated cells. The most relevant and statistic significant (p < 0.01) pathways in the experiment are associated with the genes that displayed significant differential expression and are related to intracellular signaling, oxidative stress, apoptosis, and cancer.
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Affiliation(s)
- Carolina Negrei
- Department of Toxicology, Faculty of Pharmacy, "Carol Davila" University of Medicine and Pharmacy Bucharest, Romania
| | - Ariana Hudita
- Department of Biochemistry and Molecular Biology, University of Bucharest Bucharest, Romania
| | - Octav Ginghina
- Department of Surgery, "Sf. Ioan" Clinical Emergency HospitalBucharest, Romania; Department II, Faculty of Dental Medicine, "Carol Davila" University of Medicine and PharmacyBucharest, Romania
| | - Bianca Galateanu
- Department of Biochemistry and Molecular Biology, University of Bucharest Bucharest, Romania
| | - Sorina Nicoleta Voicu
- Department of Biochemistry and Molecular Biology, University of Bucharest Bucharest, Romania
| | - Miriana Stan
- Department of Toxicology, Faculty of Pharmacy, "Carol Davila" University of Medicine and Pharmacy Bucharest, Romania
| | - Marieta Costache
- Department of Biochemistry and Molecular Biology, University of Bucharest Bucharest, Romania
| | - Concettina Fenga
- Occupational Medicine Section, Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina Messina, Italy
| | - Nikolaos Drakoulis
- Research Laboratory of Clinical Pharmacology and Pharmacogenomics, School of Health Sciences, Faculty of Pharmacy, National and Kapodistrian University of Athens Athens, Greece
| | - Aristidis M Tsatsakis
- Department of Toxicology and Forensic Sciences, Medical School, University of Crete Heraklion, Greece
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22
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Abstract
tRNA molecules undergo extensive post-transcriptional processing to generate the mature functional tRNA species that are essential for translation in all organisms. These processing steps include the introduction of numerous specific chemical modifications to nucleotide bases and sugars; among these modifications, methylation reactions are by far the most abundant. The tRNA methyltransferases comprise a diverse enzyme superfamily, including members of multiple structural classes that appear to have arisen independently during evolution. Even among closely related family members, examples of unusual substrate specificity and chemistry have been observed. Here we review recent advances in tRNA methyltransferase mechanism and function with a particular emphasis on discoveries of alternative substrate specificities and chemistry associated with some methyltransferases. Although the molecular function for a specific tRNA methylation may not always be clear, mutations in tRNA methyltransferases have been increasingly associated with human disease. The impact of tRNA methylation on human biology is also discussed.
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Affiliation(s)
- William E Swinehart
- a Center for RNA Biology and Department of Chemistry and Biochemistry ; Ohio State University ; Columbus , OH USA
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23
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Abstract
Transfer RNA (tRNA) from all organisms on this planet contains modified nucleosides, which are derivatives of the four major nucleosides. tRNA from Escherichia coli/Salmonella enterica contains 31 different modified nucleosides, which are all, except for one (Queuosine[Q]), synthesized on an oligonucleotide precursor, which through specific enzymes later matures into tRNA. The corresponding structural genes for these enzymes are found in mono- and polycistronic operons, the latter of which have a complex transcription and translation pattern. The syntheses of some of them (e.g.,several methylated derivatives) are catalyzed by one enzyme, which is position and base specific, but synthesis of some have a very complex biosynthetic pathway involving several enzymes (e.g., 2-thiouridines, N6-threonyladenosine [t6A],and Q). Several of the modified nucleosides are essential for viability (e.g.,lysidin, t6A, 1-methylguanosine), whereas deficiency in others induces severe growth defects. However, some have no or only a small effect on growth at laboratory conditions. Modified nucleosides that are present in the anticodon loop or stem have a fundamental influence on the efficiency of charging the tRNA, reading cognate codons, and preventing missense and frameshift errors. Those, which are present in the body of the tRNA, have a primarily stabilizing effect on the tRNA. Thus, the ubiquitouspresence of these modified nucleosides plays a pivotal role in the function of the tRNA by their influence on the stability and activity of the tRNA.
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The Complex Mechanism of Antimycobacterial Action of 5-Fluorouracil. ACTA ACUST UNITED AC 2015; 22:63-75. [DOI: 10.1016/j.chembiol.2014.11.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/30/2014] [Accepted: 11/03/2014] [Indexed: 11/17/2022]
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25
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Evaluation of the progression and treatment of experimental periodontitis in rats subjected to chemotherapy with 5-fluorouracil. Support Care Cancer 2014; 23:2007-17. [DOI: 10.1007/s00520-014-2563-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 12/07/2014] [Indexed: 12/14/2022]
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26
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Spenkuch F, Hinze G, Kellner S, Kreutz C, Micura R, Basché T, Helm M. Dye label interference with RNA modification reveals 5-fluorouridine as non-covalent inhibitor. Nucleic Acids Res 2014; 42:12735-45. [PMID: 25300485 PMCID: PMC4227767 DOI: 10.1093/nar/gku908] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The interest in RNA modification enzymes surges due to their involvement in epigenetic phenomena. Here we present a particularly informative approach to investigate the interaction of dye-labeled RNA with modification enzymes. We investigated pseudouridine (Ψ) synthase TruB interacting with an alleged suicide substrate RNA containing 5-fluorouridine (5FU). A longstanding dogma, stipulating formation of a stable covalent complex was challenged by discrepancies between the time scale of complex formation and enzymatic turnover. Instead of classic mutagenesis, we used differentially positioned fluorescent labels to modulate substrate properties in a range of enzymatic conversion between 6% and 99%. Despite this variegation, formation of SDS-stable complexes occurred instantaneously for all 5FU-substrates. Protein binding was investigated by advanced fluorescence spectroscopy allowing unprecedented simultaneous detection of change in fluorescence lifetime, anisotropy decay, as well as emission and excitation maxima. Determination of Kd values showed that introduction of 5FU into the RNA substrate increased protein affinity by 14× at most. Finally, competition experiments demonstrated reversibility of complex formation for 5FU-RNA. Our results lead us to conclude that the hitherto postulated long-term covalent interaction of TruB with 5FU tRNA is based on the interpretation of artifacts. This is likely true for the entire class of pseudouridine synthases.
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Affiliation(s)
- Felix Spenkuch
- Institute of Pharmacy and Biochemistry, University of Mainz, Staudingerweg 5, D-55128 Mainz, Germany
| | - Gerald Hinze
- Institute of Physical Chemistry, University of Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany
| | - Stefanie Kellner
- Institute of Pharmacy and Biochemistry, University of Mainz, Staudingerweg 5, D-55128 Mainz, Germany
| | - Christoph Kreutz
- Institute of Organic Chemistry, Center for Molecular Biosciences (CMBI), University of Innsbruck, Innrain 52A, A-60230 Innsbruck, Austria
| | - Ronald Micura
- Institute of Organic Chemistry, Center for Chemistry and Biomedicine - CCB, University of Innsbruck, Innrain 80/82, A-60230 Innsbruck, Austria
| | - Thomas Basché
- Institute of Physical Chemistry, University of Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany
| | - Mark Helm
- Institute of Pharmacy and Biochemistry, University of Mainz, Staudingerweg 5, D-55128 Mainz, Germany
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Björk GR, Hagervall TG. Transfer RNA Modification: Presence, Synthesis, and Function. EcoSal Plus 2014; 6. [PMID: 26442937 DOI: 10.1128/ecosalplus.esp-0007-2013] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Indexed: 06/05/2023]
Abstract
Transfer RNA (tRNA) from all organisms on this planet contains modified nucleosides, which are derivatives of the four major nucleosides. tRNA from Escherichia coli/Salmonella enterica serovar Typhimurium contains 33 different modified nucleosides, which are all, except one (Queuosine [Q]), synthesized on an oligonucleotide precursor, which by specific enzymes later matures into tRNA. The structural genes for these enzymes are found in mono- and polycistronic operons, the latter of which have a complex transcription and translation pattern. The synthesis of the tRNA-modifying enzymes is not regulated similarly, and it is not coordinated to that of their substrate, the tRNA. The synthesis of some of them (e.g., several methylated derivatives) is catalyzed by one enzyme, which is position and base specific, whereas synthesis of some has a very complex biosynthetic pathway involving several enzymes (e.g., 2-thiouridines, N 6-cyclicthreonyladenosine [ct6A], and Q). Several of the modified nucleosides are essential for viability (e.g., lysidin, ct6A, 1-methylguanosine), whereas the deficiency of others induces severe growth defects. However, some have no or only a small effect on growth at laboratory conditions. Modified nucleosides that are present in the anticodon loop or stem have a fundamental influence on the efficiency of charging the tRNA, reading cognate codons, and preventing missense and frameshift errors. Those that are present in the body of the tRNA primarily have a stabilizing effect on the tRNA. Thus, the ubiquitous presence of these modified nucleosides plays a pivotal role in the function of the tRNA by their influence on the stability and activity of the tRNA.
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Affiliation(s)
- Glenn R Björk
- Department of Molecular Biology, Umeå University, S-90187 Umeå, Sweden
| | - Tord G Hagervall
- Department of Molecular Biology, Umeå University, S-90187 Umeå, Sweden
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Mojardín L, Botet J, Quintales L, Moreno S, Salas M. New insights into the RNA-based mechanism of action of the anticancer drug 5'-fluorouracil in eukaryotic cells. PLoS One 2013; 8:e78172. [PMID: 24223771 PMCID: PMC3815194 DOI: 10.1371/journal.pone.0078172] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 09/18/2013] [Indexed: 01/23/2023] Open
Abstract
5-Fluorouracil (5FU) is a chemotherapeutic drug widely used in treating a range of advanced, solid tumours and, in particular, colorectal cancer. Here, we used high-density tiling DNA microarray technology to obtain the specific transcriptome-wide response induced by 5FU in the eukaryotic model Schizosaccharomyces pombe. This approach combined with real-time quantitative PCR analysis allowed us to detect splicing defects of a significant number of intron-containing mRNA, in addition to identify some rRNA and tRNA processing defects after 5FU treatment. Interestingly, our studies also revealed that 5FU specifically induced the expression of certain genes implicated in the processing of mRNA, tRNA and rRNA precursors, and in the post-transcriptional modification of uracil residues in RNA. The transcription of several tRNA genes was also significantly induced after drug exposure. These transcriptional changes might represent a cellular response mechanism to counteract 5FU damage since deletion strains for some of these up-regulated genes were hypersensitive to 5FU. Moreover, most of these RNA processing genes have human orthologs that participate in conserved pathways, suggesting that they could be novel targets to improve the efficacy of 5FU-based treatments.
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Affiliation(s)
- Laura Mojardín
- Instituto de Biología Molecular “Eladio Viñuela” (CSIC), Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Universidad Autónoma, Cantoblanco, Madrid, Spain
- * E-mail: (LM); (MS)
| | - Javier Botet
- Instituto de Biología Funcional y Genómica (CSIC/Universidad de Salamanca), Salamanca, Spain
| | - Luis Quintales
- Instituto de Biología Funcional y Genómica (CSIC/Universidad de Salamanca), Salamanca, Spain
| | - Sergio Moreno
- Instituto de Biología Funcional y Genómica (CSIC/Universidad de Salamanca), Salamanca, Spain
| | - Margarita Salas
- Instituto de Biología Molecular “Eladio Viñuela” (CSIC), Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Universidad Autónoma, Cantoblanco, Madrid, Spain
- * E-mail: (LM); (MS)
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AOKI YOSHIRO, SAKOGAWA KENJI, HIHARA JUN, EMI MANABU, HAMAI YOICHI, KONO KAZUTERU, SHI LIN, SUN JIYING, KITAO HIROYUKI, IKURA TSUYOSHI, NIIDA HIROYUKI, NAKANISHI MAKOTO, OKADA MORIHITO, TASHIRO SATOSHI. Involvement of ribonucleotide reductase-M1 in 5-fluorouracil-induced DNA damage in esophageal cancer cell lines. Int J Oncol 2013; 42:1951-60. [DOI: 10.3892/ijo.2013.1899] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 02/22/2013] [Indexed: 11/06/2022] Open
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Wang Z, Ferrer S, Moliner V, Kohen A. QM/MM calculations suggest a novel intermediate following the proton abstraction catalyzed by thymidylate synthase. Biochemistry 2013; 52:2348-58. [PMID: 23464672 DOI: 10.1021/bi400267q] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cleavage of covalent C-H bonds is one of the most energetically demanding, yet biologically essential, chemical transformations. Two C-H bond cleavages are involved in the reaction catalyzed by thymidylate synthase (TSase), which provides the sole de novo source of thymidylate (i.e., the DNA base T) for most organisms. Our QM/MM free energy calculations show that the C-H → O proton transfer has three transition states that are energetically similar but structurally diverse. These characteristics are different from our previous calculation results on the C-H → C hydride transfer, providing an explanation for differences in temperature dependences of KIEs on these two C-H bond activation steps. The calculations also suggest that the traditionally proposed covalent bond between the protein and substrate (the C6-S bond) is very labile during the multistep catalytic reaction. Collective protein motions not only assist cleavage of the C6-S bond to stabilize the transition state of the proton transfer step but also rearrange the H-bond network at the end of this step to prepare the active site for subsequent chemical steps. These computational results illustrate functionalities of specific protein residues that reconcile many previous experimental observations and provide guidance for future experiments to examine the proposed mechanisms. The synchronized conformational changes in the protein and ligands observed in our simulations demonstrate participation of protein motions in the reaction coordinate of enzymatic reactions. Our computational findings suggest the existence of new reaction intermediates not covalently bound to TSase, which may lead to a new class of drugs targeting DNA biosynthesis.
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Affiliation(s)
- Zhen Wang
- Department of Chemistry, University of Iowa, Iowa City, IA 52242-1727, USA
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31
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McCusker KP, Fujimori DG. The chemistry of peptidyltransferase center-targeted antibiotics: enzymatic resistance and approaches to countering resistance. ACS Chem Biol 2012; 7:64-72. [PMID: 22208312 DOI: 10.1021/cb200418f] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The continued ability to treat bacterial infections requires effective antibiotics. The development of new therapeutics is guided by knowledge of the mechanisms of action of and resistance to these antibiotics. Continued efforts to understand and counteract antibiotic resistance mechanisms at a molecular level have the potential to direct development of new therapeutic strategies in addition to providing insight into the underlying biochemical functions impacted by antibiotics. The interaction of antibiotics with the peptidyltransferase center and adjacent exit tunnel within the bacterial ribosome is the predominant mechanism by which antibiotics impede translation, thus stalling growth. Resistance enzymes catalyze the chemical modification of the RNA that composes these functional regions, leading to diminished binding of antibiotics. This review discusses recent advances in the elucidation of chemical mechanisms underlying resistance and driving the development of new antibiotics.
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Affiliation(s)
- Kevin P. McCusker
- Department of Cellular and Molecular Pharmacology and ‡Department of Pharmaceutical Chemistry, University of California, San Francisco, 600 16th St, MC2280, San Francisco, California 94158, United States
| | - Danica Galonić Fujimori
- Department of Cellular and Molecular Pharmacology and ‡Department of Pharmaceutical Chemistry, University of California, San Francisco, 600 16th St, MC2280, San Francisco, California 94158, United States
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32
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Yan F, Fujimori DG. RNA methylation by radical SAM enzymes RlmN and Cfr proceeds via methylene transfer and hydride shift. Proc Natl Acad Sci U S A 2011; 108:3930-4. [PMID: 21368151 PMCID: PMC3054002 DOI: 10.1073/pnas.1017781108] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
RlmN and Cfr are Radical SAM enzymes that modify a single adenosine nucleotide--A2503--in 23S ribosomal RNA. This nucleotide is positioned within the peptidyl transferase center of the ribosome, which is a target of numerous antibiotics. An unusual feature of these enzymes is their ability to carry out methylation of amidine carbons of the adenosine substrate. To gain insight into the mechanism of methylation catalyzed by RlmN and Cfr, deuterium labeling experiments were carried out. These experiments demonstrate that the newly introduced methyl group is assembled from an S-adenosyl-L-methionine (SAM)-derived methylene fragment and a hydrogen atom that had migrated from the substrate amidine carbon. Rather than activating the adenosine nucleotide of the substrate by hydrogen atom abstraction from an amidine carbon, the 5'-deoxyadenosyl radical abstracts hydrogen from the second equivalent of SAM to form the SAM-derived radical cation. This species, or its corresponding sulfur ylide, subsequently adds into the substrate, initiating hydride shift and S-adenosylhomocysteine elimination to complete the formation of the methyl group. These findings indicate that rather than acting as methyltransferases, RlmN and Cfr are methyl synthases. Together with the previously described 5'-deoxyadenosyl and 3-amino-3-carboxypropyl radicals, these findings demonstrate that all three carbon atoms attached to the sulfonium center in SAM can serve as precursors to carbon-derived radicals in enzymatic reactions.
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Affiliation(s)
- Feng Yan
- Department of Cellular and Molecular Pharmacology and Department of Pharmaceutical Chemistry, University of California, 600 16th Street, San Francisco, CA 94158
| | - Danica Galonić Fujimori
- Department of Cellular and Molecular Pharmacology and Department of Pharmaceutical Chemistry, University of California, 600 16th Street, San Francisco, CA 94158
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33
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Matuo R, Sousa FG, Escargueil AE, Soares DG, Grivicich I, Saffi J, Larsen AK, Henriques JAP. DNA repair pathways involved in repair of lesions induced by 5-fluorouracil and its active metabolite FdUMP. Biochem Pharmacol 2010; 79:147-53. [DOI: 10.1016/j.bcp.2009.08.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Revised: 08/14/2009] [Accepted: 08/17/2009] [Indexed: 11/28/2022]
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34
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Hou YM, Perona JJ. Stereochemical mechanisms of tRNA methyltransferases. FEBS Lett 2009; 584:278-86. [PMID: 19944101 DOI: 10.1016/j.febslet.2009.11.075] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 11/18/2009] [Accepted: 11/19/2009] [Indexed: 12/31/2022]
Abstract
Methylation of tRNA on the four canonical bases adds structural complexity to the molecule, and improves decoding specificity and efficiency. While many tRNA methylases are known, detailed insight into the catalytic mechanism is only available in a few cases. Of interest among all tRNA methylases is the structural basis for nucleotide selection, by which the specificity is limited to a single site, or broadened to multiple sites. General themes in catalysis include the basis for rate acceleration at highly diverse nucleophilic centers for methyl transfer, using S-adenosylmethionine as a cofactor. Studies of tRNA methylases have also yielded insights into molecular evolution, particularly in the case of enzymes that recognize distinct structures to perform identical reactions at the same target nucleotide.
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Affiliation(s)
- Ya-Ming Hou
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th St., Philadelphia, PA 19107, USA.
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35
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Behera RK, Nayak R. Expression profiling of nucleotide metabolism-related genes in human breast cancer cells after treatment with 5-fluorouracil. Cancer Invest 2009; 27:561-7. [PMID: 19219653 DOI: 10.1080/07357900802620802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
5-Fluorouracil (5-FU) is one of the most widely used drugs for treatment of cancers, including breast cancer that exhibits its anticancer activity by inhibiting DNA synthesis and also incorporated into DNA and RNA. The objective of this investigation was to find out the total nucleotide metabolism genes regulated by 5-FU in breast cancer cell line. The breast cancer cell line MCF-7 was treated with the drug 5-FU. To analyze the expression of genes, we have conducted the experiment using 1.7 k and 19k human microarray slide and confirmed the expression of genes by semiquantitative reverse transcription-polymerase chain reaction. The expression of 44 genes involved in the nucleotide metabolism pathway was quantified. Of these 44 genes analyzed, transcription of 6 genes were upregulated and 9 genes were downregulated. Earlier studies revealed that the transcription of genes for key enzymes like thymidylate synthase, thymidine kinase, and dihydropyrimidine dehydrogenase are regulated by 5-FU. This study identified some novel genes like thioredoxin reductase, ectonucleotide triphosphate dephosphorylase, and CTP synthase are regulated by 5-FU. The data also reveal large-scale perturbation in transcription of genes not involved directly in the known mechanism of action of 5-FU.
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Affiliation(s)
- Rajendra Kumar Behera
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.
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36
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Gustavsson M, Ronne H. Evidence that tRNA modifying enzymes are important in vivo targets for 5-fluorouracil in yeast. RNA (NEW YORK, N.Y.) 2008; 14:666-74. [PMID: 18314501 PMCID: PMC2271368 DOI: 10.1261/rna.966208] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We have screened a collection of haploid yeast knockout strains for increased sensitivity to 5-fluorouracil (5-FU). A total of 138 5-FU sensitive strains were found. Mutants affecting rRNA and tRNA maturation were particularly sensitive to 5-FU, with the tRNA methylation mutant trm10 being the most sensitive mutant. This is intriguing since trm10, like many other tRNA modification mutants, lacks a phenotype under normal conditions. However, double mutants for nonessential tRNA modification enzymes are frequently temperature sensitive, due to destabilization of hypomodified tRNAs. We therefore tested if the sensitivity of our mutants to 5-FU is affected by the temperature. We found that the cytotoxic effect of 5-FU is strongly enhanced at 38 degrees C for tRNA modification mutants. Furthermore, tRNA modification mutants show similar synthetic interactions for temperature sensitivity and sensitivity to 5-FU. A model is proposed for how 5-FU kills these mutants by reducing the number of tRNA modifications, thus destabilizing tRNA. Finally, we found that also wild-type cells are temperature sensitive at higher concentrations of 5-FU. This suggests that tRNA destabilization contributes to 5-FU cytotoxicity in wild-type cells and provides a possible explanation why hyperthermia can enhance the effect of 5-FU in cancer therapy.
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MESH Headings
- Antineoplastic Agents/pharmacology
- Drug Resistance, Fungal/genetics
- Fluorouracil/pharmacology
- Gene Deletion
- Genes, Fungal
- Haploidy
- Humans
- Models, Biological
- Models, Molecular
- Mutation
- Nucleic Acid Conformation
- RNA Processing, Post-Transcriptional
- RNA Stability
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Transfer/chemistry
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- Saccharomyces cerevisiae/drug effects
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Temperature
- tRNA Methyltransferases/genetics
- tRNA Methyltransferases/metabolism
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Affiliation(s)
- Marie Gustavsson
- Department of Medical Biochemistry and Microbiology, Uppsala University, SE-751 23 Uppsala, Sweden
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37
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Hoskins J, Scott Butler J. Evidence for distinct DNA- and RNA-based mechanisms of 5-fluorouracil cytotoxicity in Saccharomyces cerevisiae. Yeast 2007; 24:861-70. [PMID: 17640085 DOI: 10.1002/yea.1516] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
5-Fluorouracil (5FU) is an effective chemotherapeutic drug developed as an inhibitor of thymidylate synthetase (TS). Inhibition of TS leads to 'thymine-less death', a condition resulting from depletion of dTTP pools and misincorporation of dUTP into newly synthesized or repaired DNA. 5FU is also incorporated into RNA and a growing body of evidence suggests that RNA-based effects play a significant role in its cytotoxicity. Indeed, recent experiments in yeast showed that defects in the nuclear RNA exosome subunit Rrp6p cause hypersensitivity to 5FU. The present study asked whether the 5FU hypersensitivity of an rrp6-Delta yeast strain reflects the DNA- or RNA-based effects of 5FU. Genetic analyses suggest that while a DNA repair mutation, apn1-Delta, causes sensitivity to 5FU-induced DNA damage, an rrp6-Delta mutation causes hypersensitivity, due to the RNA-based effects of 5FU. Analysis of a strain with normal DNA and RNA metabolism grown in the presence of 5FU shows that UMP suppresses the 5FU-induced defect more than dTMP, suggesting that the RNA-based toxicity of 5FU predominates in these cells. These findings underscore the importance of understanding the RNA-based mechanism of 5FU cytotoxicity and highlight the use of yeast as a model system for elucidating its details.
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Affiliation(s)
- Jason Hoskins
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA
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Shieh FK, Reich NO. AdoMet-dependent Methyl-transfer: Glu119 Is Essential for DNA C5-Cytosine Methyltransferase M.HhaI. J Mol Biol 2007; 373:1157-68. [PMID: 17897676 DOI: 10.1016/j.jmb.2007.08.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2007] [Revised: 07/17/2007] [Accepted: 08/03/2007] [Indexed: 11/21/2022]
Abstract
The role of Glu119 in S-adenosyl-L-methionine-dependent DNA methyltransferase M.HhaI-catalyzed DNA methylation was studied. Glu119 belongs to the highly conserved Glu/Asn/Val motif found in all DNA C5-cytosine methyltransferases, and its importance for M.HhaI function remains untested. We show that formation of the covalent intermediate between Cys81 and the target cytosine requires Glu119, since conversion to Ala, Asp or Gln lowers the rate of methyl transfer 10(2)-10(6) fold. Further, unlike the wild-type M.HhaI, these mutants are not trapped by the substrate in which the target cytosine is replaced with the mechanism-based inhibitor 5-fluorocytosine. The DNA binding affinity for the Glu119Asp mutant is decreased 10(3)-fold. Thus, the ability of the enzyme to stabilize the extrahelical cytosine is coupled directly to tight DNA binding. The structures of the ternary protein/DNA/AdoHcy complexes for both the Glu119Ala and Glu119Gln mutants (2.70 A and 2.75 A, respectively) show that the flipped base is positioned nearly identically with that observed in the wild-type M.HhaI complex. A single water molecule in the Glu119Ala structure between Ala119 and the extrahelical cytosine N3 is lacking in the Glu119Gln and wild-type M.HhaI structures, and most likely accounts for this mutant's partial activity. Glu119 has essential roles in activating the target cytosine for nucleophilic attack and contributes to tight DNA binding.
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Affiliation(s)
- Fa-Kuen Shieh
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA
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39
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Sheflyan GY, Kubareva EA, Gromova ES. Methods for the covalent attachment of nucleic acids and their derivatives to proteins. RUSSIAN CHEMICAL REVIEWS 2007. [DOI: 10.1070/rc1996v065n08abeh000277] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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40
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Seiple L, Jaruga P, Dizdaroglu M, Stivers JT. Linking uracil base excision repair and 5-fluorouracil toxicity in yeast. Nucleic Acids Res 2006; 34:140-51. [PMID: 16407331 PMCID: PMC1326247 DOI: 10.1093/nar/gkj430] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Revised: 12/02/2005] [Accepted: 12/16/2005] [Indexed: 11/14/2022] Open
Abstract
5-fluorouracil (5-FU) is a widely used anticancer drug that disrupts pyrimidine nucleotide pool balances and leads to uracil incorporation in DNA, which is then recognized and removed by the uracil base excision repair (BER) pathway. Using complementary biochemical and genetic approaches we have examined the role of uracil BER in the cell killing mechanism of 5-FU. A yeast strain lacking the enzyme uracil DNA glycosylase (Ung1), which excises uracil from the DNA backbone leaving an abasic site, showed significant protection against the toxic effects of 5-FU, a G1/S cell cycle arrest phenotype, and accumulated massive amounts of U/A base pairs in its genome (approximately 4% of T/A pairs were now U/A). A strain lacking the major abasic site endonuclease of Saccharomyces cerevisiae (Apn1) showed significantly increased sensitivity to 5-FU with G2/M arrest. Thus, efficient processing of abasic sites by this enzyme is protective against the toxic effects of 5-FU. However, contrary to expectations, the Apn1 deficient strain did not accumulate intact abasic sites, indicating that another repair pathway attempts to process these sites in the absence Apn1, but that this process has catastrophic effects on genome integrity. These findings suggest that new strategies for chemical intervention targeting BER could enhance the effectiveness of this widely used anticancer drug.
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Affiliation(s)
- Lauren Seiple
- Department of Pharmacology and Molecular Sciences Johns Hopkins University School of Medicine725 North Wolfe Street Baltimore, MD 21205, USA
- Department of Chemical and Biochemical Engineering, University of Maryland Baltimore CountyBaltimore, MD 21225, USA
- Chemical Science and Technology Laboratory, National Institute of Standards and Technology GaithersburgMD 20899, USA
| | - Pawel Jaruga
- Department of Chemical and Biochemical Engineering, University of Maryland Baltimore CountyBaltimore, MD 21225, USA
- Chemical Science and Technology Laboratory, National Institute of Standards and Technology GaithersburgMD 20899, USA
| | - Miral Dizdaroglu
- Chemical Science and Technology Laboratory, National Institute of Standards and Technology GaithersburgMD 20899, USA
| | - James T. Stivers
- To whom correspondence should be addressed. Tel: +1 410 502 2758; Fax: +1 410 955 3023;
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41
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Hoshino S, Yamashita Y, Maekawa T, Shirakusa T. Effects on DNA and RNA after the administration of two different schedules of 5-fluorouracil in colorectal cancer patients. Cancer Chemother Pharmacol 2005; 56:648-52. [PMID: 15959779 DOI: 10.1007/s00280-004-0985-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2004] [Accepted: 09/24/2004] [Indexed: 11/26/2022]
Abstract
PURPOSE 5-Fluorouracil (5-FU) has two major mechanisms by which it exerts its anticancer activity. One mechanism operates through the inhibition of thymidylate synthetase (TS) by the active metabolite 5-fluorodeoxyuridine 5'-monophosphate. The other mechanism is the incorporation of 5-FU into RNA. Using tumor tissue specimens from colon carcinoma patients given 5-FU by two different modes of administration, we investigated the effects of 5-FU on DNA and RNA. EXPERIMENTAL DESIGN Group A patients received 200 mg/day of 5-FU as a rapid infusion for 5 days preoperatively, and group B patients received 200 mg/day of 5-FU as a continuous infusion for 5 days preoperatively. Postoperatively, we analyzed the 5-FU concentration, 5-FU incorporation into RNA (F-RNA), and TS inhibition rate (TSIR) in normal tissue, cancerous tissue, and lymph nodes. RESULTS The F-RNA concentration in tumor tissue from group A patients was higher than in tissue from group B patients. The TS concentrations in tumor tissue were significantly higher than in non-tumor tissue in both groups. In lymph nodes, the TSIR of group A was 78.5% and that of group B was 55.2%, a significant difference. CONCLUSION Bolus injection can be considered to be more effective with respect to RNA damage in tumor tissue. Especially in cases involving lymph node metastasis, bolus injection was effective with respect to DNA damage as well as RNA damage.
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Affiliation(s)
- Seiichirou Hoshino
- Second Department of Surgery, Fukuoka University School of Medicine, 7-45-1 Nanakuma, Jonan-ku, Fukuoka, Japan.
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42
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Garcia GA, Kittendorf JD. Transglycosylation: a mechanism for RNA modification (and editing?). Bioorg Chem 2005; 33:229-51. [PMID: 15888313 PMCID: PMC2802272 DOI: 10.1016/j.bioorg.2005.01.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 01/11/2005] [Accepted: 01/11/2005] [Indexed: 11/22/2022]
Abstract
The vast majority of the ca. 100 chemically distinct modified nucleosides in RNA appear to arise via the chemical transformation of a genetically encoded nucleoside. Two notable exceptions are queuosine and pseudouridine, which are incorporated into tRNA via transglycosylation. Transglycosylation is an extremely efficient process for incorporating highly modified bases such as queuine into RNA. Transglycosylation is also a requisite process for "isomerizing" an N-nucleoside into a C-nucleoside as is the case for pseudouridine formation. Finally, transglycosylation is an attractive possibility for certain RNA editing events (e.g., pyrimidine to purine conversions) that cannot occur via the known, more straightforward enzymatic reactions (e.g., deaminations). This review discusses what is known about the mechanisms of transglycosylation for the queuine and pseudouridine RNA modifications and will speculate about a potential role for transglycosylation in certain RNA editing events.
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Affiliation(s)
- George A. Garcia
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA
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Meyers M, Hwang A, Wagner MW, Bruening AJ, Veigl ML, Sedwick WD, Boothman DA. A role for DNA mismatch repair in sensing and responding to fluoropyrimidine damage. Oncogene 2003; 22:7376-88. [PMID: 14576845 DOI: 10.1038/sj.onc.1206941] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The phenomenon of damage tolerance, whereby cells incur DNA lesions that are nonlethal, largely ignored, but highly mutagenic, appears to play a key role in carcinogenesis. Typically, these lesions are generated by alkylation of DNA or incorporation of base analogues. This tolerance is usually a result of the loss of specific DNA repair processes, most often DNA mismatch repair (MMR). The availability of genetically matched MMR-deficient and -corrected cell systems allows dissection of the consequences of this unrepaired damage in carcinogenesis as well as the elucidation of cell cycle checkpoint responses and cell death consequences. Recent data indicate that MMR plays an important role in detecting damage caused by fluorinated pyrimidines (FPs) and represents a repair system that is probably not the primary system for detecting damage caused by these agents, but may be an important system for correcting key mutagenic lesions that could initiate carcinogenesis. In fact, clinical studies have shown that there is no benefit of FP-based adjuvant chemotherapy in colon cancer patients exhibiting microsatellite instability, a hallmark of MMR deficiency. MMR-mediated damage tolerance and futile cycle repair processes are discussed, as well as possible strategies using FPs to exploit these systems for improved anticancer therapy.
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Affiliation(s)
- Mark Meyers
- Laboratory of Molecular Stress Responses, Department of Radiation Oncology, Case Western Reserve University, Biomedical Research Building 326-East, 2109 Adelbert Road, Cleveland, OH 44106-4942, USA
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Madsen CT, Mengel-Jørgensen J, Kirpekar F, Douthwaite S. Identifying the methyltransferases for m(5)U747 and m(5)U1939 in 23S rRNA using MALDI mass spectrometry. Nucleic Acids Res 2003; 31:4738-46. [PMID: 12907714 PMCID: PMC169892 DOI: 10.1093/nar/gkg657] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
There are three sites of m(5)U modification in Escherichia coli stable RNAs: one at the invariant tRNA position U54 and two in 23S rRNA at the phylogenetically conserved positions U747 and U1939. Each of these sites is modified by its own methyltransferase, and the tRNA methyltransferase, TrmA, is well-characterised. Two open reading frames, YbjF and YgcA, are approximately 30% identical to TrmA, and here we determine the functions of these candidate methyltransferases using MALDI mass spectrometry. A purified recombinant version of YgcA retains its activity and specificity, and methylates U1939 in an RNA transcript in vitro. We were unable to generate a recombinant version of YbjF that retained in vitro activity, so the function of this enzyme was defined in vivo by engineering a ybjF knockout strain. Comparison of the methylation patterns in 23S rRNAs from YbjF(+) and YbjF(-) strains showed that the latter differed only in the lack of the m(5)U747 modification. With this report, the functions of all the E.coli m(5)U RNA methyltransferases are identified, and a more appropriate designation for YbjF would be RumB (RNA uridine methyltransferases B), in line with the recent nomenclature change for YgcA (now RumA).
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Affiliation(s)
- Christian Toft Madsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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Abstract
5-fluorouracil (5-FU) is widely used in the treatment of cancer. Over the past 20 years, increased understanding of the mechanism of action of 5-FU has led to the development of strategies that increase its anticancer activity. Despite these advances, drug resistance remains a significant limitation to the clinical use of 5-FU. Emerging technologies, such as DNA microarray profiling, have the potential to identify novel genes that are involved in mediating resistance to 5-FU. Such target genes might prove to be therapeutically valuable as new targets for chemotherapy, or as predictive biomarkers of response to 5-FU-based chemotherapy.
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Affiliation(s)
- Daniel B Longley
- Cancer Research Centre, Department of Oncology, Queen's University Belfast, University Floor, Belfast City Hospital, 97 Lisburn Road, Belfast BT9 7AB, Northern Ireland
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Huang CC, Smith CV, Glickman MS, Jacobs WR, Sacchettini JC. Crystal structures of mycolic acid cyclopropane synthases from Mycobacterium tuberculosis. J Biol Chem 2002; 277:11559-69. [PMID: 11756461 DOI: 10.1074/jbc.m111698200] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mycolic acids are major components of the cell wall of Mycobacterium tuberculosis. Several studies indicate that functional groups in the acyl chain of mycolic acids are important for pathogenesis and persistence. There are at least three mycolic acid cyclopropane synthases (PcaA, CmaA1, and CmaA2) that are responsible for these site-specific modifications of mycolic acids. To derive information on the specificity and enzyme mechanism of the family of proteins, the crystal structures of CmaA1, CmaA2, and PcaA were solved to 2-, 2-, and 2.65-A resolution, respectively. All three enzymes have a seven-stranded alpha/beta fold similar to other methyltransferases with the location and interactions with the cofactor S-adenosyl-l-methionine conserved. The structures of the ternary complexes demonstrate the position of the mycolic acid substrate binding site. Close examination of the active site reveals electron density that we believe represents a bicarbonate ion. The structures support the hypothesis that these enzymes catalyze methyl transfer via a carbocation mechanism in which the bicarbonate ion acts as a general base. In addition, comparison of the enzyme structures reveals a possible mechanism for substrate specificity. These structures provide a foundation for rational-drug design, which may lead to the development of new inhibitors effective against persistent bacteria.
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Affiliation(s)
- Chih-chin Huang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128, USA
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47
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5-Fluorouracil and Its Biomodulation in the Management of Colorectal Cancer. COLORECTAL CANCER 2002. [DOI: 10.1007/978-1-59259-160-2_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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48
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Thanedar S, Dineshkumar TK, Varshney U. The mere lack of rT modification in initiator tRNA does not facilitate formylation-independent initiation in Escherichia coli. J Bacteriol 2001; 183:7397-402. [PMID: 11717300 PMCID: PMC95590 DOI: 10.1128/jb.183.24.7397-7402.2001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Formylation of initiator methionyl-tRNA is essential for normal growth of eubacteria. However, under special conditions, it has been possible to initiate protein synthesis with unformylated initiator tRNA even in eubacteria. Earlier studies suggested that the lack of ribothymidine (rT) modification in initiator tRNA may facilitate initiation in the absence of formylation. In this report we show, by using trmA strains of Escherichia coli (defective for rT modification) and a sensitive in vivo initiation assay system, that the lack of rT modification in the initiators is not sufficient to effect formylation-independent initiation of protein synthesis.
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Affiliation(s)
- S Thanedar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
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Coenzymes of Oxidation—Reduction Reactions. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50018-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Grem JL. 5-Fluorouracil: forty-plus and still ticking. A review of its preclinical and clinical development. Invest New Drugs 2000; 18:299-313. [PMID: 11081567 DOI: 10.1023/a:1006416410198] [Citation(s) in RCA: 264] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
5-Fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine (FdUrd) are pyrimidine analogs that have been part of the therapeutic armamentarium for a variety of solid tumors for over forty years. 5-FU has customarily required intravenous administration due to poor and erratic oral bioavailability, while FdUrd has generally been employed for regional administration to the liver or the peritoneal cavity. A great deal of knowledge has been gained concerning the cellular pharmacology and mechanism of action of 5-FU since it was first synthesized in the late 1950's. A more thorough understanding of the factors influencing the metabolic activation of 5-FU and its cellular effects has generated considerable interest in combining it with both modulatory agents such as leucovorin and methotrexate that enhance its metabolism or cytotoxic effects. In addition, 5-FU has also been employed to enhance the therapeutic activity of other antineoplastic agents or modalities such as cisplatin and ionizing radiation with which it can synergize. Appreciation of the clinical pharmacology of 5-FU and FdUrd have led to a variety of schedules that are clinically useful. The preclinical and clinical pharmacology of 5-FU is reviewed to provide a basis for exploring the novel approaches to permit oral administration of 5-FU or its prodrugs that will be described in other articles in this issue.
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Affiliation(s)
- J L Grem
- Developmental Therapeutics Department, National Cancer Institute- Medicine Branch, National Naval Medical Center, Bethesda, MD 20889, USA.
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