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Mentegari E, Kissova M, Bavagnoli L, Maga G, Crespan E. DNA Polymerases λ and β: The Double-Edged Swords of DNA Repair. Genes (Basel) 2016; 7:genes7090057. [PMID: 27589807 PMCID: PMC5042388 DOI: 10.3390/genes7090057] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 07/30/2016] [Accepted: 08/24/2016] [Indexed: 12/28/2022] Open
Abstract
DNA is constantly exposed to both endogenous and exogenous damages. More than 10,000 DNA modifications are induced every day in each cell's genome. Maintenance of the integrity of the genome is accomplished by several DNA repair systems. The core enzymes for these pathways are the DNA polymerases. Out of 17 DNA polymerases present in a mammalian cell, at least 13 are specifically devoted to DNA repair and are often acting in different pathways. DNA polymerases β and λ are involved in base excision repair of modified DNA bases and translesion synthesis past DNA lesions. Polymerase λ also participates in non-homologous end joining of DNA double-strand breaks. However, recent data have revealed that, depending on their relative levels, the cell cycle phase, the ratio between deoxy- and ribo-nucleotide pools and the interaction with particular auxiliary proteins, the repair reactions carried out by these enzymes can be an important source of genetic instability, owing to repair mistakes. This review summarizes the most recent results on the ambivalent properties of these enzymes in limiting or promoting genetic instability in mammalian cells, as well as their potential use as targets for anticancer chemotherapy.
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Affiliation(s)
- Elisa Mentegari
- Institute of Molecular Genetics, IGM-CNR, via Abbiategrasso 207, 27100 Pavia, Italy.
| | - Miroslava Kissova
- Institute of Molecular Genetics, IGM-CNR, via Abbiategrasso 207, 27100 Pavia, Italy.
| | - Laura Bavagnoli
- Institute of Molecular Genetics, IGM-CNR, via Abbiategrasso 207, 27100 Pavia, Italy.
| | - Giovanni Maga
- Institute of Molecular Genetics, IGM-CNR, via Abbiategrasso 207, 27100 Pavia, Italy.
| | - Emmanuele Crespan
- Institute of Molecular Genetics, IGM-CNR, via Abbiategrasso 207, 27100 Pavia, Italy.
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Narayan S, Sharma R. Molecular mechanism of adenomatous polyposis coli-induced blockade of base excision repair pathway in colorectal carcinogenesis. Life Sci 2015; 139:145-52. [PMID: 26334567 DOI: 10.1016/j.lfs.2015.08.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/31/2015] [Accepted: 08/23/2015] [Indexed: 02/07/2023]
Abstract
Colorectal cancer (CRC) is the third leading cause of death in both men and women in North America. Despite chemotherapeutic efforts, CRC is associated with a high degree of morbidity and mortality. Thus, to develop effective treatment strategies for CRC, one needs knowledge of the pathogenesis of cancer development and cancer resistance. It is suggested that colonic tumors or cell lines harbor truncated adenomatous polyposis coli (APC) without DNA repair inhibitory (DRI)-domain. It is also thought that the product of the APC gene can modulate base excision repair (BER) pathway through an interaction with DNA polymerase β (Pol-β) and flap endonuclease 1 (Fen-1) to mediate CRC cell apoptosis. The proposed therapy with temozolomide (TMZ) exploits this particular pathway; however, a high percentage of colorectal tumors continue to develop resistance to chemotherapy due to mismatch repair (MMR)-deficiency. In the present communication, we have comprehensively reviewed a critical issue that has not been addressed previously: a novel mechanism by which APC-induced blockage of single nucleotide (SN)- and long-patch (LP)-BER play role in DNA-alkylation damage-induced colorectal carcinogenesis.
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Affiliation(s)
- Satya Narayan
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610 United States.
| | - Ritika Sharma
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610 United States
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Barakat KH, Gajewski MM, Tuszynski JA. DNA polymerase beta (pol β) inhibitors: a comprehensive overview. Drug Discov Today 2012; 17:913-20. [PMID: 22561893 DOI: 10.1016/j.drudis.2012.04.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 03/19/2012] [Accepted: 04/19/2012] [Indexed: 11/25/2022]
Abstract
Base excision repair (BER) is the fundamental pathway responsible for the elimination of damaged DNA bases and repair of DNA single-strand breaks generated spontaneously or produced by DNA-damaging agents. Among the essential enzymes that are required to achieve the BER reaction is DNA polymerase beta (pol β), which has been regarded as a potential therapeutic target. More than 60 pol β-inhibitors have been identified so far; however, most of them are either not potent or not specific enough to become a drug. In this article we compile an essential knowledge base regarding the structures, the modes of inhibition and the activities of these pharmacologically interesting molecules.
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Affiliation(s)
- Khaled H Barakat
- Department of Physics, University of Alberta, Edmonton, AB, Canada.
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Barakat K, Tuszynski J. Relaxed complex scheme suggests novel inhibitors for the lyase activity of DNA polymerase beta. J Mol Graph Model 2011; 29:702-16. [DOI: 10.1016/j.jmgm.2010.12.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 12/02/2010] [Accepted: 12/06/2010] [Indexed: 11/26/2022]
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Gao Z, Maloney DJ, Dedkova LM, Hecht SM. Inhibitors of DNA polymerase beta: activity and mechanism. Bioorg Med Chem 2008; 16:4331-40. [PMID: 18343122 DOI: 10.1016/j.bmc.2008.02.071] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 02/20/2008] [Accepted: 02/22/2008] [Indexed: 11/30/2022]
Abstract
Bioassay-guided fractionation of extracts prepared from Couepia polyandra and Edgeworthia gardneri resulted in the isolation of the DNA polymerase beta (pol beta) inhibitors oleanolic acid (1), edgeworin (2), betulinic acid (3), and stigmasterol (4). Study of these pol beta inhibitors revealed that three of them inhibited both the lyase and polymerase activities of DNA polymerase beta, while stigmasterol inhibited only the lyase activity. Further investigation indicated that the four inhibitors had substantially different effects on the DNA-pol beta binary complex that is believed to be an obligatory intermediate in the lyase reaction. It was found that the inhibitors potentiated the inhibitory action of the anticancer drug bleomycin in cultured A549 cells, without any influence on the expression of pol beta in the cells. The results of the unscheduled DNA synthesis assay support the thesis that the potentiation of bleomycin cytotoxicity by DNA pol beta inhibitors was a result of an inhibition of DNA repair synthesis.
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Affiliation(s)
- Zhijie Gao
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
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Horton JK, Wilson SH. Hypersensitivity phenotypes associated with genetic and synthetic inhibitor-induced base excision repair deficiency. DNA Repair (Amst) 2006; 6:530-43. [PMID: 17113833 PMCID: PMC1911606 DOI: 10.1016/j.dnarep.2006.10.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Single-base lesions in DNA are repaired predominantly by base excision repair (BER). DNA polymerase beta (pol beta) is the polymerase of choice in the preferred single-nucleotide BER pathway. The characteristic phenotype of mouse fibroblasts with a deletion of the pol beta gene is moderate hypersensitivity to monofunctional alkylating agents, e.g., methyl methanesulfonate (MMS). Increased sensitivity to MMS is also seen in the absence of pol beta partner proteins XRCC1 and PARP-1, and under conditions where BER efficiency is reduced by synthetic inhibitors. PARP activity plays a major role in protection against MMS-induced cytotoxicity, and cells treated with a combination of non-toxic concentrations of MMS and a PARP inhibitor undergo cell cycle arrest and die by a Chk1-dependent apoptotic pathway. Since BER-deficient cells and tumors are similarly hypersensitive to the clinically used chemotherapeutic methylating agent temozolomide, modulation of DNA damage-induced cell signaling pathways, as well as BER, are attractive targets for potentiating chemotherapy.
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Affiliation(s)
| | - Samuel H. Wilson
- * Corresponding author. Tel.: 919-541-3267; fax: 919-541-3592. E-mail address: (S.H. Wilson)
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Eitsuka T, Nakagawa K, Igarashi M, Miyazawa T. Telomerase inhibition by sulfoquinovosyldiacylglycerol from edible purple laver (Porphyra yezoensis). Cancer Lett 2004; 212:15-20. [PMID: 15246557 DOI: 10.1016/j.canlet.2004.03.019] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Revised: 01/29/2004] [Accepted: 03/17/2004] [Indexed: 11/18/2022]
Abstract
As high telomerase activity is detected in most cancer cells, telomerase represents a promising cancer therapeutic target. We investigated the inhibitory effect of sulfoquinovosyldiacylglycerol (SQDG), distributed in plants and seaweeds, on human telomerase in a cell-free system. SQDG inhibited telomerase activity dose-dependently with 50% inhibition at 22 microM, whereas monogalactosyldiacylglycerol and digalactosyldiacylglycerol did not, even at concentrations of 100 microM. Moreover, we confirmed that eicosapentaenoic acid, one of the fatty acid components of SQDG, is a potent telomerase inhibitor with 50% inhibition at 19 microM. We speculate that the structure of the sulfate group and fatty acid of SQDG is important for the potent telomerase-inhibitory effect. Our findings suggest that SQDG has potential use as a therapeutic dietary compound for telomerase inhibition.
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Affiliation(s)
- Takahiro Eitsuka
- Food and Biodynamic Chemistry Lab., Graduate School of Life Science and Agriculture, Tohoku University, Sendai 981-8555, Japan
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Hu HY, Horton JK, Gryk MR, Prasad R, Naron JM, Sun DA, Hecht SM, Wilson SH, Mullen GP. Identification of small molecule synthetic inhibitors of DNA polymerase beta by NMR chemical shift mapping. J Biol Chem 2004; 279:39736-44. [PMID: 15258144 DOI: 10.1074/jbc.m402842200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA polymerase beta (beta-pol) plays a central role in repair of damaged DNA bases by base excision repair (BER) pathways. A predominant phenotype of beta-pol null mouse fibroblasts is hypersensitivity to the DNA-methylating agent methyl methanesulfonate. Residues in the 8-kDa domain of beta-pol that seem to interact with a known natural product beta-pol inhibitor, koetjapic acid, were identified by NMR chemical shift mapping. The data implicate the binding pocket as the hydrophobic cleft between helix-2 and helix-4, which provides the DNA binding and deoxyribose phosphate lyase activities of the enzyme. Nine structurally related synthetic compounds, containing aromatic or other hydrophobic groups in combination with two carboxylate groups, were then tested. They were found to bind to the same or a very similar region on the surface of the enzyme. The ability of these compounds to potentiate methyl methanesulfonate cytotoxicity, an indicator of cellular BER capacity, in wild-type and beta-pol null mouse fibroblasts, was next ascertained. The most active and beta-pol-specific of these agents, pamoic acid, was further characterized and found to be an inhibitor of the deoxyribose phosphate lyase and DNA polymerase activities of purified beta-pol on a BER substrate. Our results illustrate that NMR-based mapping techniques can be used in the design of small molecule enzyme inhibitors including those with potential use in a clinical setting.
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Affiliation(s)
- Hong-Yu Hu
- Department of Biochemistry, University of Connecticut Health Center, Farmington, Connecticut 06032, USA
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Nagle DG, Zhou YD, Mora FD, Mohammed KA, Kim YP. Mechanism targeted discovery of antitumor marine natural products. Curr Med Chem 2004; 11:1725-56. [PMID: 15279579 PMCID: PMC2908268 DOI: 10.2174/0929867043364991] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Antitumor drug discovery programs aim to identify chemical entities for use in the treatment of cancer. Many strategies have been used to achieve this objective. Natural products have always played a major role in anticancer medicine and the unique metabolites produced by marine organisms have increasingly become major players in antitumor drug discovery. Rapid advances have occurred in the understanding of tumor biology and molecular medicine. New insights into mechanisms responsible for neoplastic disease are significantly changing the general philosophical approach towards cancer treatment. Recently identified molecular targets have created exciting new means for disrupting tumor-specific cell signaling, cell division, energy metabolism, gene expression, drug resistance and blood supply. Such tumor-specific treatments could someday decrease our reliance on traditional cytotoxicity-based chemotherapy and provide new less toxic treatment options with significantly fewer side effects. Novel molecular targets and state-of-the-art, molecular mechanism-based screening methods have revitalized antitumor research and these changes are becoming an ever-increasing component of modern antitumor marine natural products research. This review describes marine natural products identified using tumor-specific mechanism-based assays for regulators of angiogenesis, apoptosis, cell cycle, macromolecule synthesis, mitochondrial respiration, mitosis, multidrug efflux and signal transduction. Special emphasis is placed on natural products directly discovered using molecular mechanism-based screening.
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Affiliation(s)
- Dale G Nagle
- Department of Phamacognosy, National Center for Natural Products Research, and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, Mississippi 38677-1848, USA.
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Thermotropic and lyotropic phase properties of glycolipid diastereomers: role of headgroup and interfacial interactions in determining phase behaviour. Curr Opin Colloid Interface Sci 2004. [DOI: 10.1016/j.cocis.2004.01.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
The role that lipids may play in enveloped viruses is reviewed. Small lipid molecules can influence retrovirus binding to cell receptors, plasma membrane fusion, and transcription. Palmitoylation following myristoylation of viral glycoproteins is required at the transmembrane level for signal transduction as well as for virion budding and maturation. Cholesterol, ether lipids, phospholipids, platelet-activating factor, phosphatidic acids, diacylglycerols, and several analogs and derivatives influence human immunodeficiency virus (HIV) activity; when conjugated with inhibitors of the viral reverse transcriptase (RT) or aspartyl protease these compounds increase drug effectiveness. On the other hand, L-carnitine, in association with the mitochondrial cardiolipins, inhibits myopathy due to continued prescription of drugs [AZT (zidovudine), ddl (didanoside), or ddC (zalcitabine)], and the redox couple of alpha-lipoic-dihydrolipoic acid prevents production of the reactive oxygen species that trigger apoptosis of infected cells, with sphingomyelin breakdown to ceramides. Retroviral infection induces a shift from phospholipid to neutral fat synthesis in host cells, and a long antiviral, i.e., antiprotease, treatment may lead to lipodystrophy. Multitherapy involving lipids and their analogs in association with anti-RT and antiproteases might enhance the inhibition of growth and proliferation of retroviruses.
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Affiliation(s)
- J Raulin
- Université Denis Diderot (Paris 7), France.
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Deng JZ, Starck SR, Hecht SM. Pentacyclic triterpenoids from Freziera sp. that inhibit DNA polymerase beta. Bioorg Med Chem 2000; 8:247-50. [PMID: 10968284 DOI: 10.1016/s0968-0896(99)00276-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In a survey of crude plant extracts for DNA polymerase 1 inhibitors, a methyl ethyl ketone extract prepared from Freziera sp. exhibited potent inhibition of DNA polymerase beta. Bioassay-guided fractionation of the extract, guided by an assay to detect DNA polymerase beta inhibition, resulted in the isolation of six active pentacyclic triterpenoids (1-6). These triterpenoids had IC50 values ranging from 7.5 to 16 microM in the presence of bovine serum albumin (BSA) and 2.6-5.8 microM in the absence of BSA, consistent with the possibility that these inhibitors may be of use in vivo.
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Affiliation(s)
- J Z Deng
- Department of Chemistry, University of Virginia, Charlottesville 22901, USA
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Sun DA, Deng JZ, Starck SR, Hecht SM. Mispyric Acid, a New Monocyclic Triterpenoid with a Novel Skeleton from Mischocarpus pyriformis that Inhibits DNA Polymerase β. J Am Chem Soc 1999. [DOI: 10.1021/ja990208o] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Di-An Sun
- Contribution from the Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22901
| | - Jing-Zhen Deng
- Contribution from the Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22901
| | - Shelley R. Starck
- Contribution from the Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22901
| | - Sidney M. Hecht
- Contribution from the Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22901
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Ogawa A, Murate T, Suzuki M, Nimura Y, Yoshida S. Lithocholic acid, a putative tumor promoter, inhibits mammalian DNA polymerase beta. Jpn J Cancer Res 1998; 89:1154-9. [PMID: 9914784 PMCID: PMC5921720 DOI: 10.1111/j.1349-7006.1998.tb00510.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Lithocholic acid (LCA), one of the major components in secondary bile acids, promotes carcinogenesis in rat colon epithelial cells induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), which methylates DNA. Base-excision repair of DNA lesions caused by the DNA methylating agents requires DNA polymerase beta (pol beta). In the present study, we examined 17 kinds of bile acids with respect to inhibition of mammalian DNA polymerases in vitro. Among them, only LCA and its derivatives inhibited DNA polymerases, while other bile acids were not inhibitory. Among eukaryotic DNA polymerases alpha, beta, delta, epsilon, and gamma, pol beta was the most sensitive to inhibition by LCA. The inhibition mode of pol beta was non-competitive with respect to the DNA template-primer and was competitive with the substrate, dTTP, with the Ki value of 10 microM. Chemical structures at the C-7 and C-12 positions in the sterol skeleton are important for the inhibitory activity of LCA. This inhibition could contribute to the tumor-promoting activity of LCA.
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Affiliation(s)
- A Ogawa
- First Department of Surgery, Nagoya University School of Medicine
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