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Hüneke H, Langeheine M, Rode K, Jung K, Pilatz A, Fietz D, Kliesch S, Brehm R. Effects of a Sertoli cell-specific knockout of Connexin43 on maturation and proliferation of postnatal Sertoli cells. Differentiation 2023; 134:31-51. [PMID: 37839230 DOI: 10.1016/j.diff.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/06/2023] [Accepted: 09/11/2023] [Indexed: 10/17/2023]
Abstract
Adult male Sertoli cell-specific Connexin43 knockout mice (SCCx43KO) exhibit higher Sertoli cell (SC) numbers per seminiferous tubule compared to their wild type (WT) littermates. Thus, deletion of this testicular gap junction protein seems to affect the proliferative potential and differentiation of "younger" SC. Although SC have so far mostly been characterised as postmitotic cells that cease to divide and become an adult, terminally differentiated cell population at around puberty, there is rising evidence that there exist exceptions from this for a very long time accepted paradigm. Aim of this study was to investigate postnatal SC development and to figure out underlying causes for observed higher SC numbers in adult KO mice. Therefore, the amount of SC mitotic figures was compared, resulting in slightly more and prolonged detection of SC mitotic figures in KO mice compared to WT. SC counting per tubular cross section revealed significantly different time curves, and comparing proliferation rates using Bromodesoxyuridine and Sox9 showed higher proliferation rates in 8-day old KO mice. SC proliferation was further investigated by Ki67 immunohistochemistry. SC in KO mice displayed a delayed initiation of cell-cycle-inhibitor p27Kip1 synthesis and prolonged synthesis of the phosphorylated tumour suppressor pRb and proliferation marker Ki67. Thus, the higher SC numbers in adult male SCCx43KO mice may arise due to two different reasons: Firstly, in prepubertal KO mice, the proliferation rate of SC was higher. Secondly, there were differences in their ability to cease proliferation as shown by the delayed initiation of p27Kip1 synthesis and the prolonged production of phosphorylated pRb and Ki67. Immunohistochemical results indicating a prolonged period of SC proliferation in SCCx43KO were confirmed by detection of proliferating SC in 17-days-old KO mice. In conclusion, deletion of the testicular gap junction protein Cx43 might prevent normal SC maturation and might even alter also the proliferation potential of adult SC.
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Affiliation(s)
- Hanna Hüneke
- Institute of Anatomy, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Marion Langeheine
- Institute of Anatomy, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Kristina Rode
- Institute of Anatomy, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Klaus Jung
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Adrian Pilatz
- Department of Urology, Pediatric Urology and Andrology, Justus Liebig University Giessen, Giessen, Germany
| | - Daniela Fietz
- Department of Veterinary Anatomy, Histology and Embryology, Justus Liebig University Giessen, Giessen, Germany
| | - Sabine Kliesch
- Centre of Andrology and Reproductive Medicine, University of Muenster, Muenster, Germany
| | - Ralph Brehm
- Institute of Anatomy, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
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2
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Falkiewicz K, Kozak W, Zdrowowicz M, Spisz P, Chomicz-Mańka L, Torchala M, Rak J. Why 6-Iodouridine Cannot Be Used as a Radiosensitizer of DNA Damage? Computational and Experimental Studies. J Phys Chem B 2023; 127:2565-2574. [PMID: 36893332 PMCID: PMC10041638 DOI: 10.1021/acs.jpcb.3c00548] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
Previous density functional theory (DFT) studies on 6-brominated pyrimidine nucleosides suggest that 6-iodo-2'-deoxyuridine (6IdU) should act as a better radiosensitizer than its 5-iodosubstituted 2'-deoxyuridine analogue. In this work, we show that 6IdU is unstable in an aqueous solution. Indeed, a complete disappearance of the 6IdU signal was observed during its isolation by reversed-phase high-performance liquid chromatography (RP-HPLC). As indicated by the thermodynamic characteristics for the SN1-type hydrolysis of 6IdU obtained at the CAM-B3LYP/DGDZVP++ level and the polarizable continuum model (PCM) of water, 6-iodouracil (6IU) was already released quantitatively at ambient temperatures. The simulation of the hydrolysis kinetics demonstrated that a thermodynamic equilibrium was reached within seconds for the title compound. To assess the reliability of the calculations carried out, we synthesized 6-iodouridine (6IUrd), which was, unlike 6IdU, sufficiently stable in an aqueous solution at room temperature. The activation barrier for the N-glycosidic bond dissociation in 6IUrd was estimated experimentally using an Arrhenius plot. The stabilities in water calculated for 6IdU, 6IUrd, and 5-iodo-2'-deoxyuridine (5IdU) could be explained by the electronic and steric effects of the 2'-hydroxy group present in the ribose moiety. Our studies highlight the issue of the hydrolytic stability of potentially radiosensitizing nucleotides which, besides having favorable dissociative electron attachment (DEA) characteristics, must be stable in water to have any practical application.
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Affiliation(s)
- Karina Falkiewicz
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Witold Kozak
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Magdalena Zdrowowicz
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Paulina Spisz
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
- Laboratory of Intermolecular Interactions, Department of Bioinorganic Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Lidia Chomicz-Mańka
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Mieczyslaw Torchala
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Janusz Rak
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
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3
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Cui X, Zhao Y, Zhang C, Meng Q. Nitro rotation tuned dissociative electron attachment upon targeted radiosensitizer 4-substituted Z bases. Phys Chem Chem Phys 2022; 24:10356-10364. [PMID: 35438101 DOI: 10.1039/d2cp00351a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, a set of new potential radiation sensitizers (4-substituted Z-bases: 4XZ, X = F, Cl, Br, and I) are designed based on the artificial 6-amino-5-nitro-3-(1'-β-D-2'-deoxyribofuranosyl)-2(1H)-pyridone (Z), which can selectively bind to breast cancer cells. The calculated electron affinities in water solution show that the halogenated Z-bases are efficient electron acceptors which possess significant electron-withdrawing characters following the order of 4XZ > Z ≫ U. To ensure the effective electron attachment induced dissociation, we constructed the energy profiles related to the X-C bond cleavage of neutral and anionic bases. The results show that the X-C bond becomes relatively weak after the electron attachment. In particular, the electron induced dehalogenations of (4BrZ)- and (4IZ)- are low-barrier and exothermic, which support a high radiosensitivity. Furthermore, we characterized the vibrational excitation effect on the dissociative electron attachment, which demonstrates that the charge distribution can be regulated by the rotation-induced structural distortion accompanied by the electron localization on the nitro group. Also examined is the influence of base pairing on the dehalogenation, which is not only conducive to the electron-driven dissociation but is also beneficial to the stabilization of related products. The current study suggests 4BrZ and 4IZ can be regarded as potential targeted radiosensitizers with possible applications in reducing the side effects in radiotherapy.
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Affiliation(s)
- Xixi Cui
- College of Physics and Electronics, Shandong Normal University, Jinan 250358, Shandong, China.
| | - Yu Zhao
- College of Physics and Electronics, Shandong Normal University, Jinan 250358, Shandong, China.
| | - Changzhe Zhang
- College of Physics and Electronics, Shandong Normal University, Jinan 250358, Shandong, China.
| | - Qingtian Meng
- College of Physics and Electronics, Shandong Normal University, Jinan 250358, Shandong, China.
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4
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Shchukin PV, Muftakhov MV, Khatymov RV, Tuktarov RF. Resonant electron capture by 5-Br-2′-deoxyuridine. J Chem Phys 2022; 156:104304. [DOI: 10.1063/5.0077009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The results of the study of resonant electron capture by molecules of 5-Br-2′-deoxyuridine (BrdUrd) over the range of electron energies from near zero to 14 eV are described. In the thermal energy range, long-lived molecular negative ions, unstable with respect to autoneutralization and dehalogenation, have been registered. Examination of the kinetics of these decay processes led us to the conclusion that the most probable structure for molecular negative ions is that with an extended C–Br bond, which was predicted earlier using quantum-chemical calculations. Estimates have shown that the BrdUrd molecule owns a significant electronic affinity of 0.93–1.38 eV. The most intense fragmentation channel leads to the abundant formation of Br− ions. The dissociative electron attachment cross section for Br− ions formation was estimated to amount to no less than 1.65 × 10−15 cm2, indirectly implying a fairly intense formation of complementary highly reactive deoxyuridine-5-yl particles. These particles are known to be responsible for the radiosensitizing properties of BrdUrd.
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Affiliation(s)
- P. V. Shchukin
- Institute of Molecule and Crystal Physics–Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - M. V. Muftakhov
- Institute of Molecule and Crystal Physics–Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - R. V. Khatymov
- Mendeleev University of Chemical Technology of Russia, Miusskaya square, 9, Moscow 125047, Russia
| | - R. F. Tuktarov
- Institute of Molecule and Crystal Physics–Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
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Muñoz EN, Rivera HM, Gómez LA. Changes in cytoarchitecture and mobility in B16F1 melanoma cells induced by 5-Br-2'-dU coincide with Rock2, miRNAs 138-5p and 455-3p reciprocal expressions. Biochem Biophys Rep 2021; 27:101027. [PMID: 34159262 PMCID: PMC8202345 DOI: 10.1016/j.bbrep.2021.101027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 05/12/2021] [Accepted: 05/14/2021] [Indexed: 11/23/2022] Open
Abstract
ROCK2 is a protein involved in the restructuring of the cytoskeleton in cell adhesion and contractibility processes. miR-138-5p and miR-455-3p regulate Rock2 expression, cell proliferation, migration, and invasion in different experimental cell models. However, their participation in the cytoarchitecture and mobility of B16F1 melanoma cells exposed to 5-Br-2'-dU is partially known. This work aimed to analyze ROCK2 and miRs 138-5p and 455-3p expression associated with morphological and mobility changes of B16F1 mouse melanoma cells exposed to the thymidine analog 5-Bromo-2'-deoxyuridine (5-Br-2'-dU). We observed an increase (2.2X n = 3, p < 0.05) in the cell area, coinciding with an increase in cell diameter (1.27X n = 3, p < 0.05), as well as greater cell granularity, capacity for circularization, adhesion, which was associated with more significant polymerization of F-actin, collapsed in the intermediate filaments of vimentin (VIM), and coinciding with a decrease in migration (87%). Changes coincided with a decrease in Rock2 mRNA expression (2.88X n = 3, p < 0.05), increased vimentin and a reciprocal decrease in miR-138-5p (1.8X), and an increase in miR-455-3p (2.39X). The Rock2 kinase inhibitor Y27632 partially rescued these changes. These results suggest ROCK2 and VIM regulate the morphological and mobility changes of B16 melanoma cells after exposure to 5-Br-2'-dU, and its expression may be reciprocally regulated, at least in part, by miR-138-5p and miR-455-3p.
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Affiliation(s)
- Esther Natalia Muñoz
- Molecular Physiology Group, Scientific and Technological Research, Public Health Research, Instituto Nacional de Salud de Colombia, Bogotá, D.C., Colombia
- Department of Physiological Sciences, Faculty of Medicine, Universidad Nacional de Colombia, Bogotá, D.C., Colombia
| | - Hernán Mauricio Rivera
- Molecular Physiology Group, Scientific and Technological Research, Public Health Research, Instituto Nacional de Salud de Colombia, Bogotá, D.C., Colombia
| | - Luis Alberto Gómez
- Molecular Physiology Group, Scientific and Technological Research, Public Health Research, Instituto Nacional de Salud de Colombia, Bogotá, D.C., Colombia
- Department of Physiological Sciences, Faculty of Medicine, Universidad Nacional de Colombia, Bogotá, D.C., Colombia
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Mendes M, Kossoski F, Lozano AI, Pereira-da-Silva J, Rodrigues R, Ameixa J, Jones NC, Hoffmann SV, Ferreira da Silva F. Excited States of Bromopyrimidines Probed by VUV Photoabsorption Spectroscopy and Theoretical Calculations. Int J Mol Sci 2021; 22:6460. [PMID: 34208711 PMCID: PMC8235550 DOI: 10.3390/ijms22126460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/10/2021] [Accepted: 06/12/2021] [Indexed: 11/16/2022] Open
Abstract
We report absolute photoabsorption cross sections for gas-phase 2- and 5-bromopyrimidine in the 3.7-10.8 eV energy range, in a joint theoretical and experimental study. The measurements were carried out using high-resolution vacuum ultraviolet synchrotron radiation, with quantum chemical calculations performed through the nuclear ensemble approach in combination with time-dependent density functional theory, along with additional Franck-Condon Herzberg-Teller calculations for the first absorption band (3.7-4.6 eV). The cross sections of both bromopyrimidines are very similar below 7.3 eV, deviating more substantially from each other at higher energies. In the 7.3-9.0 eV range where the maximum cross-section is found, a single and broad band is observed for 5-bromopyrimidine, while more discernible features appear in the case of 2-bromopyrimidine. Several π* ← π transitions account for the most intense bands, while weaker ones are assigned to transitions involving the nitrogen and bromine lone pairs, the antibonding σ*Br orbital, and the lower-lying Rydberg states. A detailed comparison with the available photo-absorption data of bromobenzene is also reported. We have found significant differences regarding the main absorption band, which is more peaked in bromobenzene, becoming broader and shifting to higher energies in both bromopyrimidines. In addition, there is a significant suppression of vibrational structures and of Rydberg states in the pair of isomers, most noticeably for 2-bromopyrimidine.
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Affiliation(s)
- Mónica Mendes
- CEFITEC, Departamento de Física, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (A.I.L.); (J.P.-d.-S.); (R.R.); (J.A.); (F.F.d.S.)
| | - Fábris Kossoski
- Laboratoire de Chimie et Physique Quantiques (UMR 5626), Université de Toulouse, CNRS, UPS, CEDEX 09, 31062 Toulouse, France
| | - Ana I. Lozano
- CEFITEC, Departamento de Física, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (A.I.L.); (J.P.-d.-S.); (R.R.); (J.A.); (F.F.d.S.)
| | - João Pereira-da-Silva
- CEFITEC, Departamento de Física, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (A.I.L.); (J.P.-d.-S.); (R.R.); (J.A.); (F.F.d.S.)
| | - Rodrigo Rodrigues
- CEFITEC, Departamento de Física, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (A.I.L.); (J.P.-d.-S.); (R.R.); (J.A.); (F.F.d.S.)
| | - João Ameixa
- CEFITEC, Departamento de Física, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (A.I.L.); (J.P.-d.-S.); (R.R.); (J.A.); (F.F.d.S.)
| | - Nykola C. Jones
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark; (N.C.J.); (S.V.H.)
| | - Søren V. Hoffmann
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark; (N.C.J.); (S.V.H.)
| | - Filipe Ferreira da Silva
- CEFITEC, Departamento de Física, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (A.I.L.); (J.P.-d.-S.); (R.R.); (J.A.); (F.F.d.S.)
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Ke CC, Li JJ, Wu HP, Kuo WW, Chen YA, Lu CH, Wang HE, Hsu SM, Hsieh YJ, Liu RS. Enhancement of IUdR Radiosensitization in Cancer Therapy by Low-Energy Transmission X Ray Irradiation. J Med Biol Eng 2021. [DOI: 10.1007/s40846-021-00616-0] [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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8
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Habas K, Brinkworth MH, Anderson D. A male germ cell assay and supporting somatic cells: its application for the detection of phase specificity of genotoxins in vitro. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2020; 23:91-106. [PMID: 32046612 DOI: 10.1080/10937404.2020.1724577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Male germ stem cells are responsible for transmission of genetic information to the next generation. Some chemicals exert a negative impact on male germ cells, either directly, or indirectly affecting them through their action on somatic cells. Ultimately, these effects might inhibit fertility, and may exhibit negative consequences on future offspring. Genotoxic anticancer agents may interact with DNA in germ cells potentially leading to a heritable germline mutation. Experimental information in support of this theory has not always been reproducible and suitable in vivo studies remain limited. Thus, alternative male germ cell tests, which are now able to detect phase specificity of such agents, might be used by regulatory agencies to help evaluate the potential risk of mutation. However, there is an urgent need for such approaches for identification of male reproductive genotoxins since this area has until recently been dependent on in vivo studies. Many factors drive alternative approaches, including the (1) commitment to the principles of the 3R's (Replacement, Reduction, and Refinement), (2) time-consuming nature and high cost of animal experiments, and (3) new opportunities presented by new molecular analytical assays. There is as yet currently no apparent appropriate model of full mammalian spermatogenesis in vitro, under the REACH initiative, where new tests introduced to assess genotoxicity and mutagenicity need to avoid unnecessary testing on animals. Accordingly, a battery of tests used in conjunction with the high throughput STAPUT gravity sedimentation was recently developed for purification of male germ cells to investigate genotoxicity for phase specificity in germ cells. This system might be valuable for the examination of phases previously only available in mammals with large-scale studies of germ cell genotoxicity in vivo. The aim of this review was to focus on this alternative approach and its applications as well as on chemicals of known in vivo phase specificities used during this test system development.
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Affiliation(s)
- Khaled Habas
- Faculty of Life Sciences, University of Bradford, Bradford, UK
| | | | - Diana Anderson
- Faculty of Life Sciences, University of Bradford, Bradford, UK
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9
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Makurat S, Spisz P, Kozak W, Rak J, Zdrowowicz M. 5-Iodo-4-thio-2'-Deoxyuridine as a Sensitizer of X-ray Induced Cancer Cell Killing. Int J Mol Sci 2019; 20:E1308. [PMID: 30875879 PMCID: PMC6470520 DOI: 10.3390/ijms20061308] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 03/12/2019] [Indexed: 12/21/2022] Open
Abstract
Nucleosides, especially pyrimidines modified in the C5-position, can act as radiosensitizers via a mechanism that involves their enzymatic triphosphorylation, incorporation into DNA, and a subsequent dissociative electron attachment (DEA) process. In this paper, we report 5-iodo-4-thio-2'-deoxyuridine (ISdU) as a compound that can effectively lead to ionizing radiation (IR)-induced cellular death, which is proven by a clonogenic assay. The test revealed that the survival of cells, pre-treated with 10 or 100 µM solution of ISdU and exposed to 0.5 Gy of IR, was reduced from 78.4% (for non-treated culture) to 67.7% and to 59.8%, respectively. For a somewhat higher dose of 1 Gy, the surviving fraction was reduced from 68.2% to 54.9% and to 40.8% for incubation with 10 or 100 µM ISdU, respectively. The cytometric analysis of histone H2A.X phosphorylation showed that the radiosensitizing effect of ISdU was associated, at least in part, with the formation of double-strand breaks. Moreover, the cytotoxic test against the MCF-7 breast cancer cell line and human dermal fibroblasts (HDFa line) confirmed low cytotoxic activity of ISdU. Based on the results of steady state radiolysis of ISdU with a dose of 140 Gy and quantum chemical calculations explaining the origin of the MS detected radioproducts, the molecular mechanism of sensitization by ISdU was proposed. In conclusion, we found ISdU to be a potential radiosensitizer that could improve anticancer radiotherapy.
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Affiliation(s)
- Samanta Makurat
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
| | - Paulina Spisz
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
| | - Witold Kozak
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
| | - Janusz Rak
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
| | - Magdalena Zdrowowicz
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
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10
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Ameixa J, Arthur-Baidoo E, Meißner R, Makurat S, Kozak W, Butowska K, Ferreira da Silva F, Rak J, Denifl S. Low-energy electron-induced decomposition of 5-trifluoromethanesulfonyl-uracil: A potential radiosensitizer. J Chem Phys 2018; 149:164307. [PMID: 30384761 DOI: 10.1063/1.5050594] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
5-trifluoromethanesulfonyl-uracil (OTfU), a recently proposed radiosensitizer, is decomposed in the gas-phase by attachment of low-energy electrons. OTfU is a derivative of uracil with a triflate (OTf) group at the C5-position, which substantially increases its ability to undergo effective electron-induced dissociation. We report a rich assortment of fragments formed upon dissociative electron attachment (DEA), mostly by simple bond cleavages (e.g., dehydrogenation or formation of OTf-). The most favorable DEA channel corresponds to the formation of the triflate anion alongside with the reactive uracil-5-yl radical through the cleavage of the O-C5 bond, particularly at about 0 eV. Unlike for halouracils, the parent anion was not detected in our experiments. The experimental findings are accounted by a comprehensive theoretical study carried out at the M06-2X/aug-cc-pVTZ level. The latter comprises the thermodynamic thresholds for the formation of the observed anions calculated under the experimental conditions (383.15 K and 3 × 10-11 atm). The energy-resolved ion yield of the dehydrogenated parent anion, (OTfU-H)-, is discussed in terms of vibrational Feshbach resonances arising from the coupling between the dipole bound state and vibrational levels of the transient negative ion. We also report the mass spectrum of the cations obtained through ionization of OTfU by electrons with a kinetic energy of 70 eV. The current study endorses OTfU as a potential radiosensitizer agent with possible applications in radio-chemotherapy.
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Affiliation(s)
- J Ameixa
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - E Arthur-Baidoo
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - R Meißner
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - S Makurat
- Laboratory of Biological Sensitizers, Physical Chemistry Department, Faculty of Chemistry, University of Gdańsk, 80-308 Gdańsk, Poland
| | - W Kozak
- Laboratory of Biological Sensitizers, Physical Chemistry Department, Faculty of Chemistry, University of Gdańsk, 80-308 Gdańsk, Poland
| | - K Butowska
- Laboratory of Biophysics, Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of the University of Gdańsk and Medical University of Gdańsk, 80-307 Gdańsk, Poland
| | - F Ferreira da Silva
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal
| | - J Rak
- Laboratory of Biological Sensitizers, Physical Chemistry Department, Faculty of Chemistry, University of Gdańsk, 80-308 Gdańsk, Poland
| | - S Denifl
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
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11
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Ligasová A, Koberna K. DNA Replication: From Radioisotopes to Click Chemistry. Molecules 2018; 23:molecules23113007. [PMID: 30453631 PMCID: PMC6278288 DOI: 10.3390/molecules23113007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 11/14/2018] [Accepted: 11/15/2018] [Indexed: 12/14/2022] Open
Abstract
The replication of nuclear and mitochondrial DNA are basic processes assuring the doubling of the genetic information of eukaryotic cells. In research of the basic principles of DNA replication, and also in the studies focused on the cell cycle, an important role is played by artificially-prepared nucleoside and nucleotide analogues that serve as markers of newly synthesized DNA. These analogues are incorporated into the DNA during DNA replication, and are subsequently visualized. Several methods are used for their detection, including the highly popular click chemistry. This review aims to provide the readers with basic information about the various possibilities of the detection of replication activity using nucleoside and nucleotide analogues, and to show the strengths and weaknesses of those different detection systems, including click chemistry for microscopic studies.
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Affiliation(s)
- Anna Ligasová
- Faculty of Medicine and Dentistry, Institute of Molecular and Translational Medicine, Palacký University in Olomouc, Hněvotínská 5, 779 00 Olomouc, Czech Republic.
| | - Karel Koberna
- Faculty of Medicine and Dentistry, Institute of Molecular and Translational Medicine, Palacký University in Olomouc, Hněvotínská 5, 779 00 Olomouc, Czech Republic.
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12
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Westphal K, Skotnicki K, Bobrowski K, Rak J. Radiation damage to single stranded oligonucleotide trimers labelled with 5-iodopyrimidines. Org Biomol Chem 2018; 14:9331-9337. [PMID: 27714271 DOI: 10.1039/c6ob01713d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The radiolysis of deoxygenated aqueous solution containing trimeric oligonucleotides labelled with iodinated pyrimidines and Tris-HCl as the hydroxyl radical scavenger leads to electron attachment to the halogenated bases that mainly results in single strand breaks. The iodinated trimers are 2-fold more sensitive to solvated electrons than the brominated oligonucleotides, which is explained by the barrier-free dissociation of the iodinated base anions. The present study fills the literature gap concerning the chemistry triggered by ionizing radiation in the iodinated pyrimidines incorporated into DNA.
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Affiliation(s)
- Kinga Westphal
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
| | - Konrad Skotnicki
- Centre of Radiation Research and Technology, Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw, Poland
| | - Krzysztof Bobrowski
- Centre of Radiation Research and Technology, Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw, Poland
| | - Janusz Rak
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
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13
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Wityk P, Wieczór M, Makurat S, Chomicz-Mańka L, Czub J, Rak J. Dominant Pathways of Adenosyl Radical-Induced DNA Damage Revealed by QM/MM Metadynamics. J Chem Theory Comput 2017; 13:6415-6423. [PMID: 29117674 DOI: 10.1021/acs.jctc.7b00978] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Brominated nucleobases sensitize double stranded DNA to hydrated electrons, one of the dominant genotoxic species produced in hypoxic cancer cells during radiotherapy. Such radiosensitizers can therefore be administered locally to enhance treatment efficiency within the solid tumor while protecting the neighboring tissue. When a solvated electron attaches to 8-bromoadenosine, a potential sensitizer, the dissociation of bromide leads to a reactive C8 adenosyl radical known to generate a range of DNA lesions. In the current work, we propose a multiscale computational approach to elucidate the mechanism by which this unstable radical causes further damage in genomic DNA. We employed a combination of classical molecular dynamics conformational sampling and QM/MM metadynamics to study the thermodynamics and kinetics of plausible reaction pathways in a realistic model, bridging between different time scales of the key processes and accounting for the spatial constraints in DNA. The obtained data allowed us to build a kinetic model that correctly predicts the products predominantly observed in experimental settings-cyclopurine and β-elimination (single strand break) lesions-with their ratio and yield dependent on the effective lifetime of the radical species. To date, our study provides the most complete description of purine radical reactivity in double stranded DNA, explaining the radiosensitizing action of electrophilic purines in molecular detail as well as providing a conceptual framework for the computational modeling of competing reaction pathways in biomolecules.
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Affiliation(s)
- Paweł Wityk
- Faculty of Chemistry, University of Gdańsk , Wita Stwosza 63, 80-952 Gdańsk, Poland
| | - Miłosz Wieczór
- Department of Physical Chemistry, Faculty of Chemistry, Gdańsk University of Technology , Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Samanta Makurat
- Faculty of Chemistry, University of Gdańsk , Wita Stwosza 63, 80-952 Gdańsk, Poland
| | - Lidia Chomicz-Mańka
- Faculty of Chemistry, University of Gdańsk , Wita Stwosza 63, 80-952 Gdańsk, Poland
| | - Jacek Czub
- Department of Physical Chemistry, Faculty of Chemistry, Gdańsk University of Technology , Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Janusz Rak
- Faculty of Chemistry, University of Gdańsk , Wita Stwosza 63, 80-952 Gdańsk, Poland
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14
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Andrews MG, Del Castillo LM, Ochoa-Bolton E, Yamauchi K, Smogorzewski J, Butler SJ. BMPs direct sensory interneuron identity in the developing spinal cord using signal-specific not morphogenic activities. eLife 2017; 6. [PMID: 28925352 PMCID: PMC5605194 DOI: 10.7554/elife.30647] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 08/24/2017] [Indexed: 02/06/2023] Open
Abstract
The Bone Morphogenetic Protein (BMP) family reiteratively signals to direct disparate cellular fates throughout embryogenesis. In the developing dorsal spinal cord, multiple BMPs are required to specify sensory interneurons (INs). Previous studies suggested that the BMPs act as concentration-dependent morphogens to direct IN identity, analogous to the manner in which sonic hedgehog patterns the ventral spinal cord. However, it remains unresolved how multiple BMPs would cooperate to establish a unified morphogen gradient. Our studies support an alternative model: BMPs have signal-specific activities directing particular IN fates. Using chicken and mouse models, we show that the identity, not concentration, of the BMP ligand directs distinct dorsal identities. Individual BMPs promote progenitor patterning or neuronal differentiation by their activation of different type I BMP receptors and distinct modulations of the cell cycle. Together, this study shows that a 'mix and match' code of BMP signaling results in distinct classes of sensory INs.
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Affiliation(s)
- Madeline G Andrews
- Department of Neurobiology, University of California, Los Angeles, United States.,Neuroscience Graduate Program, University of California, Los Angeles, United States.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, United States
| | - Lorenzo M Del Castillo
- Department of Neurobiology, University of California, Los Angeles, United States.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, United States.,CIRM Bridges to Research Program, California State University, Northridge, United States
| | - Eliana Ochoa-Bolton
- Department of Neurobiology, University of California, Los Angeles, United States.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, United States.,CIRM Bridges to Research Program, California State University, Northridge, United States
| | - Ken Yamauchi
- Department of Neurobiology, University of California, Los Angeles, United States.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, United States
| | - Jan Smogorzewski
- Department of Dermatology, University of Southern California, California, United States
| | - Samantha J Butler
- Department of Neurobiology, University of California, Los Angeles, United States.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, United States
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15
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Peccati F, Mai S, González L. Insights into the deactivation of 5-bromouracil after ultraviolet excitation. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2017; 375:20160202. [PMID: 28320905 PMCID: PMC5360901 DOI: 10.1098/rsta.2016.0202] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/03/2016] [Indexed: 06/06/2023]
Abstract
5-Bromouracil is a nucleobase analogue that can replace thymine in DNA strands and acts as a strong radiosensitizer, with potential applications in molecular biology and cancer therapy. Here, the deactivation of 5-bromouracil after ultraviolet irradiation is investigated in the singlet and triplet manifold by accurate quantum chemistry calculations and non-adiabatic dynamics simulations. It is found that, after irradiation to the bright ππ* state, three main relaxation pathways are, in principle, possible: relaxation back to the ground state, intersystem crossing (ISC) and C-Br photodissociation. Based on accurate MS-CASPT2 optimizations, we propose that ground-state relaxation should be the predominant deactivation pathway in the gas phase. We then employ different electronic structure methods to assess their suitability to carry out excited-state dynamics simulations. MRCIS (multi-reference configuration interaction including single excitations) was used in surface hopping simulations to compute the ultrafast ISC dynamics, which mostly involves the 1nOπ* and 3ππ* states.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.
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Affiliation(s)
- Francesca Peccati
- Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Sebastian Mai
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
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16
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Nakada Y, Canseco DC, Thet S, Abdisalaam S, Asaithamby A, Santos CX, Shah AM, Zhang H, Faber JE, Kinter MT, Szweda LI, Xing C, Hu Z, Deberardinis RJ, Schiattarella G, Hill JA, Oz O, Lu Z, Zhang CC, Kimura W, Sadek HA. Hypoxia induces heart regeneration in adult mice. Nature 2016; 541:222-227. [DOI: 10.1038/nature20173] [Citation(s) in RCA: 439] [Impact Index Per Article: 54.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 10/21/2016] [Indexed: 01/08/2023]
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17
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Affiliation(s)
- Arthur Jones
- Radiotherapeutic Department, St Bartholomew's Hospital, London
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18
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Churchill CDM, Eriksson LA, Wetmore SD. DNA Distortion Caused by Uracil-Containing Intrastrand Cross-Links. J Phys Chem B 2016; 120:1195-204. [PMID: 26830475 DOI: 10.1021/acs.jpcb.5b10381] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Four uracil-containing intrastrand cross-links have been detected in human cells upon UV irradiation of 5-bromouracil-containing DNA, namely 5'-G[8-5]U-3', 5'-U[5-8]G-3', 5'-A[8-5]U-3', and 5'-A[2-5]U-3'. These lesions feature unique composition and connectivity compared with other intrastrand cross-links reported in the literature. For the first time, structural information obtained using molecular dynamics (MD) simulations reveal that all four lesions distort the DNA helix, which can involve an extrahelical location of the cross-link, changes in the helical interactions of the complementary nucleotides, or disruption of hydrogen bonding in the flanking base pairs up to two positions from the cross-linked site; however, the degree of distortion varies between the cross-links, being affected by the sequence, nucleobase-nucleobase connectivity, and the purine involved. Most importantly, the relative distortion of the damaged DNA provides the first structural explanation for the observed abundances of the four uracil-containing cross-links. Furthermore, the highly distorted conformations suggest that these lesions will likely have severe implications for DNA replication and repair processes in cells.
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Affiliation(s)
- Cassandra D M Churchill
- Department of Chemistry and Biochemistry, University of Lethbridge , 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Leif A Eriksson
- Department of Chemistry and Molecular Biology, University of Gothenburg , Box 462, Göteborg 405 30, Sweden
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge , 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
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19
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Cheng HY, Chen YC, Lin CJ, Liu WC, Hsieh SH. Temporary anion states of radiosensitive halopyrimidines: Shape and core-excited resonances. COMPUT THEOR CHEM 2016. [DOI: 10.1016/j.comptc.2015.10.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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20
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Chomicz L, Petrovici A, Archbold I, Adhikary A, Kumar A, Sevilla MD, Rak J. An ESR and DFT study of hydration of the 2'-deoxyuridine-5-yl radical: a possible hydroxyl radical intermediate. Chem Commun (Camb) 2014; 50:14605-8. [PMID: 25306924 PMCID: PMC4213299 DOI: 10.1039/c4cc07089e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mechanism of radiation-induced frank strand break formation in irradiated 5-bromo-2'-deoxyuridine (BrdU)-labelled DNA is still unclear despite the proven radiosensitizing properties of BrdU. Combination of ESR spectroscopy and quantum chemical modelling points to a simple reaction between the uridine-5-yl radical and water molecules that produces the genotoxic hydroxyl radical.
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Affiliation(s)
- Lidia Chomicz
- Department of Chemistry, University of Gdansk, 80-308 Gdansk, Poland
| | - Alex Petrovici
- Department of Chemistry, Oakl and University, Rochester, Michigan 48309, USA
| | - Ian Archbold
- Department of Chemistry, Oakl and University, Rochester, Michigan 48309, USA
| | - Amitava Adhikary
- Department of Chemistry, Oakl and University, Rochester, Michigan 48309, USA
| | - Anil Kumar
- Department of Chemistry, Oakl and University, Rochester, Michigan 48309, USA
| | - Michael D. Sevilla
- Department of Chemistry, Oakl and University, Rochester, Michigan 48309, USA
| | - Janusz Rak
- Department of Chemistry, University of Gdansk, 80-308 Gdansk, Poland
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21
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Golon Ł, Chomicz L, Rak J. Electron-induced single strand break in the nucleotide of 5- and 6-bromouridine. A DFT study. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.08.049] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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22
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Barbosa AS, Bettega MHF. Shape resonances in low-energy-electron collisions with halopyrimidines. J Chem Phys 2014; 139:214301. [PMID: 24320374 DOI: 10.1063/1.4834776] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report calculated cross sections for elastic collisions of low-energy electrons with halopyrimidines, namely, 2-chloro, 2-bromo, and 5-bromopyrimidine. We employed the Schwinger multichannel method with pseudopotentials to compute the cross sections in the static-exchange and static-exchange plus polarization levels of approximation for energies up to 10 eV. We found four shape resonances for each molecule: three of π* nature localized on the ring and one of σ* nature localized along the carbon-halogen bond. We compared the calculated positions of the resonances with the electron transmission spectroscopy data measured by Modelli et al. [J. Phys. Chem. A 115, 10775 (2011)]. In general the agreement between theory and experiment is good. In particular, our results show the existence of a π* temporary anion state of A2 symmetry for all three halopyrimidines, in agreement with the dissociative electron attachment spectra also reported by Modelli et al. [J. Phys. Chem. A 115, 10775 (2011)].
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Affiliation(s)
- Alessandra Souza Barbosa
- Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-990 Curitiba, Paraná, Brazil
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23
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Zylicz-Stachula A, Polska K, Skowron P, Rak J. Artificial plasmid labeled with 5-bromo-2'-deoxyuridine: a universal molecular system for strand break detection. Chembiochem 2014; 15:1409-12. [PMID: 24850054 DOI: 10.1002/cbic.201402082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Indexed: 01/08/2023]
Abstract
DNA strand breaks (SBs) are among the most cytotoxic forms of DNA damage, and their residual levels correlate directly with cell death. Hence, the type and amount of SBs is directly related to the efficacy of a given anticancer therapy. In this study, we describe a molecular tool that can differentiate between single (SSBs) and double (DSBs) strand breaks and also assess them quantitatively. Our method involves PCR amplification of a linear DNA fragment labeled with a sensitizing nucleotide, circularization of that fragment, and enzymatic introduction of supercoils to transform the circular relaxed form of the synthesized plasmid into a supercoiled one. After exposure of the molecule to a damaging factor, SSB and DSB levels can be easily assayed with gel electrophoresis. We applied this method to prepare an artificial plasmid labeled with 5-bromo-2'-deoxyuridine and to assay SBs photoinduced in the synthesized plasmid.
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24
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Zdrowowicz M, Michalska B, Zylicz-Stachula A, Rak J. Photoinduced single strand breaks and intrastrand cross-links in an oligonucleotide labeled with 5-bromouracil. J Phys Chem B 2014; 118:5009-16. [PMID: 24766391 DOI: 10.1021/jp500192z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
5-Bromouracil (BrU) is photoreactive toward near UVB photons and can be introduced into genomic DNA during its biosynthesis in cells. However, PCR seems to be a simpler approach, which can be used to obtain labeled DNA similar to that synthesized within the cell. In the current work, PCR has been employed and optimized in order to substitute all thymines (besides those present in starters) with BrU in the dsDNA fragment of 80 base pairs (bp) in length. The modified oligonucleotide was irradiated with 300 nm photons in a buffered aqueous solution (pH = 7) and digested with a cocktail of enzymes specific to the phosphodiester bond cleavage. Initially, the extent of damage in the intact photolyte was measured with DHPLC. Then, the digested reaction mixture was subjected to HPLC and MS analyses and, in addition to the formation of 5-bromo-2'-deoxuyridine, which proves the occurrence of single strand breaks (SSBs) due to irradiation, U∧U and U∧C dimers were found, whose molecular structure was confirmed by MS/MS analysis. Although the abundance of such tandem lesions is lower than that of the SSB type, they pose a potent threat to genome integrity. Thus, our findings shed new light on the photosensitizing properties of BrU toward DNA.
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Affiliation(s)
- Magdalena Zdrowowicz
- Faculty of Chemistry, University of Gdańsk , Wita Stwosza 63, 80-308 Gdańsk, Poland
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25
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Chomicz L, Furmanchuk A, Leszczynski J, Rak J. Electron induced single strand break and cyclization: a DFT study on the radiosensitization mechanism of the nucleotide of 8-bromoguanine. Phys Chem Chem Phys 2014; 16:6568-74. [PMID: 24569645 DOI: 10.1039/c3cp55411b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cleavage of the O-P bond in 8-bromo-2'-deoxyguanosine-3',5'-diphosphate (BrdGDP), considered as a model of single strand break (SSB) in labelled double-stranded DNA (ds DNA), is investigated at the B3LYP/6-31++G(d,p) level. The thermodynamic and kinetic characteristics of the formation of SSB are compared to those related to the 5',8-cycloguanosine lesion. The first reaction step, common to both damage types, which is the formation of the reactive guanyl radical, proceeds with a barrier-free or low-barrier release of the bromide anion. The guanyl radical is then stabilized by hydrogen atom transfer from the C3' or C5' sites of the 2'-deoxyribose moiety to its C8 center. The C3' path, via the O-P bond cleavage, leads to a ketone derivative (the SSB model), while the C5' path is more likely to yield 5',8-cycloguanosine.
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Affiliation(s)
- Lidia Chomicz
- Department of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
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26
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Bigda JJ, Koszałka P. Wacław Szybalski's contribution to immunotherapy: HGPRT mutation & HAT selection as first steps to gene therapy and hybrid techniques in mammalian cells. Gene 2013; 525:158-61. [DOI: 10.1016/j.gene.2013.03.099] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Revised: 02/27/2013] [Accepted: 03/07/2013] [Indexed: 01/04/2023]
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27
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Chomicz L, Leszczynski J, Rak J. Electron-Induced Degradation of 8-Bromo-2′-deoxyadenosine 3′,5′-Diphosphate, a DNA Radiosensitizing Nucleotide. J Phys Chem B 2013; 117:8681-8. [DOI: 10.1021/jp4022689] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lidia Chomicz
- Department
of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952
Gdańsk, Poland
| | - Jerzy Leszczynski
- Interdisciplinary
Nanotoxicity
Center, Jackson State University, Jackson,
Mississippi, 39217, United States
| | - Janusz Rak
- Department
of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952
Gdańsk, Poland
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28
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Cell diameter measurements obtained with a handheld cell counter could be used as a surrogate marker of G2/M arrest and apoptosis in colon cancer cell lines exposed to SN-38. Biochem Biophys Res Commun 2013; 434:753-9. [PMID: 23583407 DOI: 10.1016/j.bbrc.2013.03.128] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 03/30/2013] [Indexed: 11/20/2022]
Abstract
In vitro assessment of chemosensitivity are important for experiments evaluating cancer therapies. The Scepter 2.0 cell counter, an automated handheld device based on the Coulter principle of impedance-based particle detection, enables the accurate discrimination of cell populations according to cell size and volume. In this study, the effects of SN-38, the active metabolite of irinotecan, on the colon cancer cell lines HCT116 and HT29 were evaluated using this device. The cell count data obtained with the Scepter counter were compared with those obtained with the (3)H-thymidine uptake assay, which has been used to measure cell proliferation in many previous studies. In addition, we examined whether the changes in the size distributions of these cells reflected alterations in the frequency of cell cycle arrest and/or apoptosis induced by SN-38 treatment. In our experiments using the Scepter 2.0 cell counter, the cell counts were demonstrated to be accurate and reproducible measure and alterations of cell diameter reflected G2/M cell cycle arrest and apoptosis. Our data show that easy-to-use cell counting tools can be utilized to evaluate the cell-killing effects of novel treatments on cancer cells in vitro.
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29
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Park Y, Polska K, Rak J, Wagner JR, Sanche L. Fundamental mechanisms of DNA radiosensitization: damage induced by low-energy electrons in brominated oligonucleotide trimers. J Phys Chem B 2012; 116:9676-82. [PMID: 22812492 DOI: 10.1021/jp304964r] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The replacement of nucleobases with brominated analogs enhances DNA radiosensitivity. We examine the chemistry of low-energy electrons (LEEs) in this sensitization process by experiments with thin films of the oligonucleotide trimers TBrXT, where BrX = 5-BrU (5-bromouracil), 5-BrC (5-bromocytosine), 8-BrA (8-bromoadenine), or 8-BrG (8-bromoguanine). The products induced from irradiation of thin (∼ 2.5 nm) oligonucleotide films, with 10 eV electrons, under ultrahigh vacuum (UHV) are analyzed by HPLC-UV. The number of damaged brominated trimers ranges from about 12 to 15 × 10(-3) molecules per incident electron, whereas under the identical conditions, these numbers drop to 4-7 × 10(-3) for the same, but nonbrominated oligonucleotides. The results of HPLC analysis show that the main degradation pathway of trinucleotides containing brominated bases involve debromination (i.e., loss of the bromine atom and its replacement with a hydrogen atom). The electron-induced sum of products upon bromination increases by factors of 2.1 for the pyrimidines and 3.2 for the purines. Thus, substitution of any native nucleobase with a brominated one in simple models of DNA increases LEE-induced damage to DNA and hence its radiosensitivity. Furthermore, besides the brominated pyrimidines that have already been tested in clinical trials, brominated purines not only appear to be promising sensitizers for radiotherapy, but could provide a higher degree of radiosensitization.
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Affiliation(s)
- Yeunsoo Park
- Center for Radiobiology and Radiotherapy, Department of Nuclear Medicine and Radiobiology, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
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30
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Chomicz L, Rak J, Storoniak P. Electron-induced elimination of the bromide anion from brominated nucleobases. A computational study. J Phys Chem B 2012; 116:5612-9. [PMID: 22510158 DOI: 10.1021/jp3008738] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The enhancement of radiodamage to DNA labeled with halonucleobases is attributed to the reactive radical produced from a halonucleobase by the attachment of an electron. We examined at the B3LYP/6-31++G** level electron capture by four brominated nucleobases (BrNBs): 8-bromo-9-methyladenine, 8-bromo-9-methylguanine, 5-bromo-1-methylcytosine, and 5-bromo-1-methyluracil followed by the release of the bromide anion and a nucleobase radical. We demonstrate that neutral BrNBs in both gas and aqueous phases are better electron acceptors than unsubstituted NBs and that resulting anion radicals, BrNBs(•-), can easily transform into the product complex of the bromide anion and the nucleobase radical ([Br(-)···NB(•)]). The overall thermodynamic stimulus for the process starting with the neutral BrNB and ending with the isolated bromide anion and the NB(•) radical is similar in the case of all four BrNBs studied, which suggests their comparable radiosensitizing capabilities.
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Affiliation(s)
- Lidia Chomicz
- Department of Chemistry, University of Gdańsk , Sobieskiego 18, 80-952 Gdańsk, Poland
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31
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Polska K, Rak J, Bass AD, Cloutier P, Sanche L. Electron stimulated desorption of anions from native and brominated single stranded oligonucleotide trimers. J Chem Phys 2012; 136:075101. [PMID: 22360262 PMCID: PMC3813477 DOI: 10.1063/1.3685587] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We measured the low energy electron stimulated desorption (ESD) of anions from thin films of native (TXT) and bromine monosubstituted (TBrXT) oligonucleotide trimers deposited on a gold surface (T = thymidine, X = T, deoxycytidine (C), deoxyadenosine (A) or deoxyguanosine (G), Br = bromine). The desorption of H(-), CH(3)(-)/NH(-), O(-)/NH(2)(-), OH(-), CN(-), and Br(-) was induced by 0 to 20 eV electrons. Dissociative electron attachment, below 12 eV, and dipolar dissociation, above 12 eV, are responsible for the formation of these anions. The comparison of the results obtained for the native and brominated trimers suggests that the main pathways of TBrXT degradation correspond to the release of the hydride and bromide anions. Significantly, the presence of bromine in oligonucleotide trimers blocks the electron-induced degradation of nuclobases as evidenced by a dramatic decrease in CN(-) desorption. An increase in the yields of OH(-) is also observed. The debromination yield of particular oligonucleotides diminishes in the following order: BrdU > BrdA > BrdG > BrdC. Based on these results, 5-bromo-2(')-deoxyuridine appears to be the best radiosensitizer among the studied bromonucleosides.
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Affiliation(s)
- Katarzyna Polska
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland
| | - Janusz Rak
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland
| | - Andrew D. Bass
- Research Group in the Radiation Sciences, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
| | - Pierre Cloutier
- Research Group in the Radiation Sciences, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
| | - Léon Sanche
- Research Group in the Radiation Sciences, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
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Churchill CDM, Eriksson LA, Wetmore SD. Formation mechanism and structure of a guanine-uracil DNA intrastrand cross-link. Chem Res Toxicol 2011; 24:2189-99. [PMID: 22060045 DOI: 10.1021/tx2003239] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The formation and structure of the 5'-G[8-5]U-3' intrastrand cross-link are studied using density functional theory and molecular dynamics simulations due to the potential role of this lesion in the activity of 5-halouracils in antitumor therapies. Upon UV irradiation of 5-halouracil-containing DNA, a guanine radical cation reacts with the uracil radical to form the cross-link, which involves phosphorescence or an intersystem crossing and a rate-determining step of bond formation. Following ionizing radiation, guanine and the uracil radical react, with a rate-limiting step involving hydrogen atom removal. Although cross-link formation from UV radiation is favored, comparison of calculated reaction thermokinetics with that for related experimentally observed purine-pyrimidine cross-links suggests this lesion is also likely to form from ionizing radiation. For the first time, the structure of 5'-G[8-5]U-3' within DNA is identified by molecular dynamics simulations. Furthermore, three conformations of cross-linked DNA are revealed, which differ in the configuration of the complementary bases. Distortions, such as unwinding, are localized to the cross-linked dinucleotide and complementary nucleotides, with minimal changes to the flanking bases. Global changes to the helix, such as bending and groove alterations, parallel cisplatin-induced distortions, which indicate 5'-G[8-5]U-3', may contribute to the cytotoxicity of halouracils in tumor cell DNA using similar mechanisms.
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Affiliation(s)
- Cassandra D M Churchill
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, Canada T1K 3M4
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Morgenroth A, Vogg AT, Mottaghy FM, Schmaljohann J. Targeted endoradiotherapy using nucleotides. Methods 2011; 55:203-14. [PMID: 21782950 DOI: 10.1016/j.ymeth.2011.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/24/2011] [Accepted: 06/28/2011] [Indexed: 11/15/2022] Open
Abstract
Increased cellular proliferation is an integral part of the cancer phenotype. Hence, the sustained and continued demand on supply of DNA building blocks during the DNA replication presents a potential target for therapeutic intervention. For this propose, the α and Auger electron emitting nucleotides analogs are attractive for targeted endoradiotherapy, given that DNA of malignant cells is selectively addressed. This review summarizes development and preclinical and clinical studies of endoradiotherapeutic acting nucleoside analogs with a special focus on thymidine analogs.
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Affiliation(s)
- Agnieszka Morgenroth
- Department of Nuclear Medicine, University Hospital Aachen, RWTH, Pauwelsstraße 30, D-52074 Aachen, Germany.
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Abstract
Deinococcus radiodurans is a robust bacterium best known for its capacity to repair massive DNA damage efficiently and accurately. It is extremely resistant to many DNA-damaging agents, including ionizing radiation and UV radiation (100 to 295 nm), desiccation, and mitomycin C, which induce oxidative damage not only to DNA but also to all cellular macromolecules via the production of reactive oxygen species. The extreme resilience of D. radiodurans to oxidative stress is imparted synergistically by an efficient protection of proteins against oxidative stress and an efficient DNA repair mechanism, enhanced by functional redundancies in both systems. D. radiodurans assets for the prevention of and recovery from oxidative stress are extensively reviewed here. Radiation- and desiccation-resistant bacteria such as D. radiodurans have substantially lower protein oxidation levels than do sensitive bacteria but have similar yields of DNA double-strand breaks. These findings challenge the concept of DNA as the primary target of radiation toxicity while advancing protein damage, and the protection of proteins against oxidative damage, as a new paradigm of radiation toxicity and survival. The protection of DNA repair and other proteins against oxidative damage is imparted by enzymatic and nonenzymatic antioxidant defense systems dominated by divalent manganese complexes. Given that oxidative stress caused by the accumulation of reactive oxygen species is associated with aging and cancer, a comprehensive outlook on D. radiodurans strategies of combating oxidative stress may open new avenues for antiaging and anticancer treatments. The study of the antioxidation protection in D. radiodurans is therefore of considerable potential interest for medicine and public health.
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Ross HH, Rahman M, Levkoff LH, Millette S, Martin-Carreras T, Dunbar EM, Reynolds BA, Laywell ED. Ethynyldeoxyuridine (EdU) suppresses in vitro population expansion and in vivo tumor progression of human glioblastoma cells. J Neurooncol 2011; 105:485-98. [PMID: 21643840 DOI: 10.1007/s11060-011-0621-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 05/25/2011] [Indexed: 11/30/2022]
Abstract
Thymidine analogs (TAs) are synthetic nucleosides that incorporate into newly synthesized DNA. Halogenated pyrimidines (HPs), such as bromodeoxyuridine (BrdU), are a class of TAs that can be detected with antibodies and are commonly used for birthdating individual cells and for assessing the proliferative index of cell populations. It is well established that HPs can act as radiosensitizers when incorporated into DNA chains, but they are generally believed not to impair normal cell function in the absence of secondary stressors. However, we and others have shown that HP incorporation leads to a sustained suppression of cell cycle progression in mammalian cells, resulting in cellular senescence in somatic cells. In addition, we have shown that HP incorporation results in delayed tumor progression in a syngeneic rat model of glioma. Here we examine ethynyldeoxyuridine (EdU), a newly developed and alkylated TA, for its anti-cancer activity, both in vitro and in vivo. We show that EdU, like HPs, leads to a severe reduction in the proliferation rate of normal and transformed cells in vitro. Unlike HPs, however, EdU incorporation also causes DNA damage resulting in the death of a substantial subset of treated cells. When administered over an extended time as a monotherapy to mice bearing subcutaneous xenografts of human glioblastoma multiforme tumors, EdU significantly reduces tumor volume and increases survival without apparent significant toxicity. These results, combined with the fact that EdU readily crosses the blood-brain barrier, support the continued investigation of EdU as a potential therapy for malignant brain tumors.
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Affiliation(s)
- Heather H Ross
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA
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Storoniak P, Rak J, Polska K, Blancafort L. Local Excitation of the 5-Bromouracil Chromophore in DNA. Computational and UV Spectroscopic Studies. J Phys Chem B 2011; 115:4532-7. [DOI: 10.1021/jp201028a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Piotr Storoniak
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland
| | - Janusz Rak
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland
| | - Katarzyna Polska
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland
| | - Lluís Blancafort
- Institute of Computational Chemistry, Department of Chemistry, University of Girona, Campus de Montilivi, 17071 Girona, Spain
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O'Brien TF, Coons AH. STUDIES ON ANTIBODY PRODUCTION : VII. THE EFFECT OF 5-BROMODEOXYURIDINE ON THE IN VITRO ANAMNESTIC ANTIBODY RESPONSE. ACTA ACUST UNITED AC 2010; 117:1063-74. [PMID: 19867230 PMCID: PMC2137596 DOI: 10.1084/jem.117.6.1063] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Incorporation of 5-bromodeoxyuridine (BUDR) in the culture medium for the 2nd, 3rd, or 4th day after in vitro antigen stimulation of rabbit popliteal lymph node fragments suppressed the in vitro anamnestic antibody response described previously. Before or after this 3-day period, BUDR had no measurable effect. The results suggest that the antibody response in this in vitro system depends upon cell multiplication during this period.
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Affiliation(s)
- T F O'Brien
- Department of Bacteriology and Immunology, Harvard Medical School, Boston
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KIHLMAN BA. THE EFFECT OF 5-HALOGENATED DEOXYURIDINES ON THE FREQUENCY OF X-RAY-INDUCED CHROMOSOMAL ABERRATIONS IN VICIA FABA. Hereditas 2009. [DOI: 10.1111/j.1601-5223.1963.tb01886.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Heshmati E, Abdolmaleki P, Mozdarani H, Sarvestani AS. Effects of halogen substitution on Watson–Crick base pairing: A possible mechanism for radiosensitivity. Bioorg Med Chem Lett 2009; 19:5256-60. [DOI: 10.1016/j.bmcl.2009.06.105] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 05/21/2009] [Accepted: 06/18/2009] [Indexed: 11/15/2022]
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TYM R, TODD PW. The Sensitization by Iododeoxyuridine of Cultured Human Cells to the Lethal Effect of X-rays and Heavy Ions. ACTA ACUST UNITED AC 2009; 8:589-603. [PMID: 14278133 DOI: 10.1080/09553006414550721] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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X-ray sensitivity of HeLa S3 cells in the G2 phase comparison of two methods of synchronization. Biophys J 2008; 7:77-94. [PMID: 19210983 DOI: 10.1016/s0006-3495(67)86576-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The sensitivity of HeLa S3 cells to 220 kv X-rays was measured in terms of cell survival (colony development) during the G2 phase of the cell generation cycle, employing two procedures designed to free G2 cultures from contaminating cells from other phases of the cycle. Treatment of synchronous cultures (obtained initially by mitotic selection) with high specific activity tritiated thymidine (HSA-(3)HTdR) selectively eliminated S phase cells, while addition of vinblastine permitted removal of cells as they entered mitosis. It was found that HeLa S3 cells become increasingly sensitive as they progress through G2. The pattern of sensitivity fluctuations observed in synchronous HeLa S3 populations selected by the foregoing method was compared with that found in synchronous cultures prepared by the HSA-(3)HTdR method of Whitmore. The latter method had been used previously with mouse L cells, which were found to undergo a different pattern of sensitivity fluctuations. The two methods yield similar results for HeLa cells in the S and G2 phases of the cycle. It may be concluded, therefore, that the discrepancies between HeLa and mouse L cells do not arise from methodological factors, but represent fundamental differences between the cell types.
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Abstract
The thymidine analog bromodeoxyuridine (BrdU) is incorporated into newly synthesized DNA and has been shown to increase the susceptibility of incorporating cells to ionizing radiation. However, in the absence of secondary stressors, BrdU is thought to substitute relatively benignly for thymidine and is commonly used to "birth-date" proliferative cells. We report a novel antiproliferative effect of BrdU on cancer cells, which is independent of its role in radiosensitization. A single, brief in vitro exposure to BrdU induces a profound and sustained reduction in the proliferation rate of all cancer cells examined. Cells do not die but variably up-regulate some senescence-associated proteins as they accumulate in the G1 phase of the cell cycle. Bromodeoxyuridine also impairs the proliferative capacity of primary tumor-initiating human glioma cells and may therefore represent a means of targeting cancer stem cells. Finally, conservative in vivo BrdU regimens--in the absence of any other treatment--significantly suppress the progression of gliomas in the highly aggressive, syngeneic RG2 model. These results suggest that BrdU may have an important role as an adjunctive therapeutic for a wide variety of cancers based on new insights into its effect as a negative regulator of cell cycle progression.
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Abstract
Pten is a negative regulator of the Akt pathway, and its inactivation is believed to be an etiological factor in many tumor types. Pten+/- mice are susceptible to a variety of spontaneous tumor types, depending on strain background. Pten+/- mice, in lung tumor-sensitive and -resistant background strains, were treated with a tobacco carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), to determine whether allelic Pten deletion can cooperate with NNK in carcinogenesis in lung or other tissues. In lung tumor-resistant C57BL/6 Pten+/- or +/+ mice, NNK treatment did not lead to any lung tumors and did not increase the incidence or severity of tumors previously reported for this strain. In contrast, in a lung tumor-susceptible pseudo-A/J strain, there was a dose-dependent increase in lung tumor size in Pten+/- compared with +/+ mice, although there was no increase in multiplicity. No other tumor types were observed in pseudo-A/J Pten+/- mice regardless of NNK treatment. Lung tumors from these Pten+/- mice had K-ras mutations, retained Pten expression and had similar Akt pathway activation as lung tumors from +/+ mice. Therefore, deletion of a single copy of Pten does not substantially add to the lung tumor phenotype conferred by mutation of K-ras by NNK, and there is likely no selective advantage for loss of the second Pten allele in lung tumor initiation.
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Ross HH, Levkoff LH, Marshall GP, Caldeira M, Steindler DA, Reynolds BA, Laywell ED. Bromodeoxyuridine induces senescence in neural stem and progenitor cells. Stem Cells 2008; 26:3218-27. [PMID: 18802036 DOI: 10.1634/stemcells.2008-0299] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Bromodeoxyuridine (BrdU) is a halogenated pyrimidine that incorporates into newly synthesized DNA during the S phase. BrdU is used ubiquitously in cell birthdating studies and as a means of measuring the proliferative index of various cell populations. In the absence of secondary stressors, BrdU is thought to incorporate relatively benignly into replicating DNA chains. However, we report here that a single, low-dose pulse of BrdU exerts a profound and sustained antiproliferative effect in cultured murine stem and progenitor cells. This is accompanied by altered terminal differentiation, cell morphology, and protein expression consistent with the induction of senescence. There is no evidence of a significant increase in spontaneous cell death; however, cells are rendered resistant to chemically induced apoptosis. Finally, we show that a brief in vivo BrdU regimen reduces the proliferative potential of subsequently isolated subependymal zone neurosphere-forming cells. We conclude, therefore, that BrdU treatment induces a senescence pathway that causes a progressive decline in the replication of rapidly dividing stem/progenitor cells, suggesting a novel and uncharacterized effect of BrdU. This finding is significant in that BrdU-incorporating neural stem/progenitor cells and their progeny should not be expected to behave normally with respect to proliferative potential and downstream functional parameters. This effect highlights the need for caution when results based on long-term BrdU tracking over multiple rounds of replication are interpreted. Conversely, the reliable induction of senescence in stem/progenitor cells in vitro and in vivo may yield a novel platform for molecular studies designed to address multiple aspects of aging and neurogenesis.
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Affiliation(s)
- Heather H Ross
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610, USA
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Breunig JJ, Arellano JI, Macklis JD, Rakic P. Everything that glitters isn't gold: a critical review of postnatal neural precursor analyses. Cell Stem Cell 2008; 1:612-27. [PMID: 18371403 DOI: 10.1016/j.stem.2007.11.008] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Adult neurogenesis research has made enormous strides in the last decade but has been complicated by several failures to replicate promising findings. Prevalent use of highly sensitive methods with inherent sources of error has led to extraordinary conclusions without adequate crossvalidation. Perhaps the biggest culprit is the reliance on molecules involved in DNA synthesis and genetic markers to indicate neuronal neogenesis. In this Protocol Review, we present an overview of common methodological issues in the field and suggest alternative approaches, including viral vectors, siRNA, and inducible transgenic/knockout mice. A multipronged approach will enhance the overall rigor of research on stem cell biology and related fields by allowing increased replication of findings between groups and across systems.
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Affiliation(s)
- Joshua J Breunig
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06510, USA
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Kagawa Y, Noge I, Higashigawa M, Komada Y. Combined Antitumor Effect of Cyclophosphamide and Bromodeoxyuridine in BDF1 Mice Bearing L1210 Ascites Tumors. Biol Pharm Bull 2008; 31:57-61. [DOI: 10.1248/bpb.31.57] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Yoshiyuki Kagawa
- Department of Clinical Pharmaceutics, School of Pharmaceutical Sciences, University of Shizuoka
| | - Ichiro Noge
- Department of Clinical Pharmaceutics, School of Pharmaceutical Sciences, University of Shizuoka
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Masterson JC, O'Dea S. 5-Bromo-2-deoxyuridine activates DNA damage signalling responses and induces a senescence-like phenotype in p16-null lung cancer cells. Anticancer Drugs 2007; 18:1053-68. [PMID: 17704656 DOI: 10.1097/cad.0b013e32825209f6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
5-Bromo-2-deoxyuridine (BrdU) is a thymidine analogue that is incorporated into replicating DNA. Although originally designed as a chemotherapeutic agent, sublethal concentrations of BrdU have long been known to alter the growth and phenotype of a wide range of cell types. Mechanisms underlying these BrdU-mediated effects remain unknown, however. We have characterized the effects of BrdU on A549 lung cancer cells by examining DNA damage responses, cell cycle effects and phenotypic changes. A549 cells express wild-type p53, but are p16-null. Sublethal concentrations of BrdU evoke a DNA damage response in these cells that involves the activation of Chk1, Chk2 and p53. Increased numbers of enlarged nuclei and multinucleated cells are evident in the treated populations. Cell cycle inhibition occurs, resulting in reduced proliferation and accumulation of cells in the S, G2/M and G0 phases. BrdU induces an early inhibition of p21 expression that coincides with nuclear localization of proliferating cell nuclear antigen. Subsequently, p21 levels increase, whereas proliferating cell nuclear antigen levels decrease compared with control cells. Upregulation of p27 and p57 expression also occurs. By day 7 of exposure to BrdU, treated cells acquire a senescent-like phenotype with an increase in cell size, granularity and beta-galactosidase activity. We conclude that BrdU induces a DNA damage response in A549 cells, which results in reduced proliferation mitotic exit and phenotypic changes that resemble senescence.
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Affiliation(s)
- Joanne C Masterson
- Institute of Immunology, Biology Department, National University of Ireland Maynooth, Ireland
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