1
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Fang Q. The Versatile Attributes of MGMT: Its Repair Mechanism, Crosstalk with Other DNA Repair Pathways, and Its Role in Cancer. Cancers (Basel) 2024; 16:331. [PMID: 38254819 PMCID: PMC10814553 DOI: 10.3390/cancers16020331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
O6-methylguanine-DNA methyltransferase (MGMT or AGT) is a DNA repair protein with the capability to remove alkyl groups from O6-AlkylG adducts. Moreover, MGMT plays a crucial role in repairing DNA damage induced by methylating agents like temozolomide and chloroethylating agents such as carmustine, and thereby contributes to chemotherapeutic resistance when these agents are used. This review delves into the structural roles and repair mechanisms of MGMT, with emphasis on the potential structural and functional roles of the N-terminal domain of MGMT. It also explores the development of cancer therapeutic strategies that target MGMT. Finally, it discusses the intriguing crosstalk between MGMT and other DNA repair pathways.
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Affiliation(s)
- Qingming Fang
- Department of Biochemistry and Structural Biology, Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, TX 78229, USA
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2
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Fillion A, Franco Pinto J, Granzhan A. Harnessing an emissive guanine surrogate to design small-molecule fluorescent chemosensors of O6-methylguanine-DNA-methyltransferase (MGMT). Org Biomol Chem 2022; 20:1888-1892. [PMID: 35174383 DOI: 10.1039/d2ob00208f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
The fluorescence properties of an emissive guanine surrogate, thienoguanine (thGN, 2-aminothieno[3,4-d]pyrimidin-4(3H)-one), were exploited to design two real-time chemosensors of O6-methylguanine-DNA-methyltransferase (MGMT), a key DNA repair enzyme involved in the resistance to DNA-alkylating anti-cancer drugs though direct reversal of O6-alkylated guanine adducts.
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Affiliation(s)
- Alexandra Fillion
- CNRS UMR9187, Inserm U1196, Institut Curie, PSL Research University, 91405 Orsay, France.
- CNRS UMR9187, Inserm U1196, Université Paris Saclay, 91405 Orsay, France
| | - Jaime Franco Pinto
- CNRS UMR9187, Inserm U1196, Institut Curie, PSL Research University, 91405 Orsay, France.
- CNRS UMR9187, Inserm U1196, Université Paris Saclay, 91405 Orsay, France
| | - Anton Granzhan
- CNRS UMR9187, Inserm U1196, Institut Curie, PSL Research University, 91405 Orsay, France.
- CNRS UMR9187, Inserm U1196, Université Paris Saclay, 91405 Orsay, France
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3
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Mazurek M, Rola R. The implications of nitric oxide metabolism in the treatment of glial tumors. Neurochem Int 2021; 150:105172. [PMID: 34461111 DOI: 10.1016/j.neuint.2021.105172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 08/03/2021] [Accepted: 08/21/2021] [Indexed: 12/20/2022]
Abstract
Glial tumors are the most common intracranial malignancies. Unfortunately, despite such a high prevalence, patients' prognosis is usually poor. It is related to the high invasiveness, tendency to relapse and the resistance of tumors to traditional methods of treatment. An important link in the aspect of these issues may be nitric oxide (NO) metabolism. It is a very complex mechanism with multidirectional effects on the neoplastic process. Depending on the concentration axis, it can both exert pro-tumor action as well as contribute to the inhibition of tumorigenesis. The latest observations show that the control of its metabolism can be very helpful in the development of new methods of treating gliomas, as well as in increasing the effectiveness of the agents currently used. The influence of nitric oxide and nitric oxide synthase (NOS) activity on glioma stem cells seem to be of particular importance. The use of specific inhibitors may allow the reduction of tumor growth and its tendency to relapse. Another important feature of GSCs is their conditioning of glioma resistance to traditional forms of treatment. Recent studies have shown that modulation of NO metabolism can suppress this effect, preventing the induction of radio and chemoresistance. Moreover, nitric oxide is involved in the regulation of a number of immune mechanisms. Adequate modulation of its metabolism may contribute to the induction of an anti-tumor response in the patients' immune system.
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Affiliation(s)
- Marek Mazurek
- Chair and Department of Neurosurgery and Paediatric Neurosurgery, Medical University in Lublin, Poland.
| | - Radosław Rola
- Chair and Department of Neurosurgery and Paediatric Neurosurgery, Medical University in Lublin, Poland
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4
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Kostka T, Empl MT, Seiwert N, Geisen SM, Hoffmann P, Adam J, Seeger B, Shay JW, Christmann M, Sturla SJ, Fahrer J, Steinberg P. Repair of O6-carboxymethylguanine adducts by O6-methylguanine-DNA methyltransferase in human colon epithelial cells. Carcinogenesis 2021; 42:1110-1118. [PMID: 34115837 DOI: 10.1093/carcin/bgab049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/23/2021] [Accepted: 06/09/2021] [Indexed: 11/13/2022] Open
Abstract
The protein O6-methylguanine-DNA methyltransferase (MGMT) is able to repair the mutagenic O6-methylguanine adduct back to guanine. In this context, it may protect against colorectal cancer (CRC) formation associated with N-nitroso compounds. Such compounds may be endogenously formed by nitrosylation of amino acids, which can give rise to mutagenic O6-methylguanine (O6-MeG) and O6-carboxymethylguanine (O6-CMG) adducts. It is well-established that O6-MeG is repaired by MGMT. However, up to now, whether O6-CMG is repaired by this enzyme remains unresolved. Therefore, the aim of the present study was to analyze the fate of both types of O6-guanine adducts in the presence and absence of MGMT activity. To this end, MGMT activity was efficiently blocked by its chemical inhibitor O6-benzylguanine in human colon epithelial cells (HCEC). Exposure of cells to azaserine (AZA) caused significantly higher levels of both O6-MeG and O6-CMG adducts in MGMT-inhibited cells, with O6-CMG as the more abundant DNA lesion. Interestingly, MGMT inhibition did not result in higher levels of AZA-induced DNA strand breaks in spite of elevated DNA adduct levels. In contrast, MGMT inhibition significantly increased DNA strand break formation after exposure to temozolomide (TMZ), a drug that exclusively generates O6-MeG adducts. In line with this finding, the viability of the cells was moderately reduced by TMZ upon MGMT inhibition, whereas no clear effect was observed in cells treated with AZA. In conclusion, our study clearly shows that O6-CMG is repaired by MGMT in HCEC, thereby suggesting that MGMT might play an important role as a tumor suppressor in diet-mediated CRC.
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Affiliation(s)
- Tina Kostka
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany.,Institute of Food Science and Human Nutrition, Gottfried Wilhelm Leibniz University Hannover, 30167 Hannover, Germany
| | - Michael T Empl
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Nina Seiwert
- Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, Kaiserslautern, Germany
| | - Susanne M Geisen
- Department of Health Sciences and Technology, ETH Zurich, 8092 Zurich, Switzerland
| | - Pascal Hoffmann
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Janine Adam
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Bettina Seeger
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany.,Institute for Food Quality and Food Safety, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Markus Christmann
- Department of Toxicology, University Medical Center Mainz, 55131 Mainz, Germany
| | - Shana J Sturla
- Department of Health Sciences and Technology, ETH Zurich, 8092 Zurich, Switzerland
| | - Jörg Fahrer
- Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, Kaiserslautern, Germany
| | - Pablo Steinberg
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany.,Max Rubner-Institut, Federal Research Institute of Nutrition and Food, 76131 Karlsruhe, Germany
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5
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Single symbiotic cell transcriptome sequencing of coral. Genomics 2020; 112:5305-5312. [DOI: 10.1016/j.ygeno.2020.10.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 09/22/2020] [Accepted: 10/16/2020] [Indexed: 12/17/2022]
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6
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Wängler B, Schirrmacher R, Wängler C. Aiming at the tumor-specific accumulation of MGMT-inhibitors: First description of a synthetic strategy towards inhibitor-peptide conjugates. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2020.151840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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7
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Yu W, Zhang L, Wei Q, Shao A. O 6-Methylguanine-DNA Methyltransferase (MGMT): Challenges and New Opportunities in Glioma Chemotherapy. Front Oncol 2020; 9:1547. [PMID: 32010632 PMCID: PMC6979006 DOI: 10.3389/fonc.2019.01547] [Citation(s) in RCA: 136] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 12/20/2019] [Indexed: 12/18/2022] Open
Abstract
Chemoresistance has been a significant problem affecting the efficacy of drugs targeting tumors for decades. MGMT, known as O6-methylguanine-DNA methyltransferase, is a DNA repair enzyme that plays an important role in chemoresistance to alkylating agents. Hence, MGMT is considered a promising target for tumor treatment. Several methods are employed to detect MGMT, each with its own advantages and disadvantages. Some of the detection methods are; immunohistochemistry, methylation-specific PCR (MSP), pyrophosphate sequencing, MGMT activity test, and real-time quantitative PCR. Methylation of MGMT promoter is a key predictor of whether alkylating agents can effectively control glioma cells. The prognostic value of MGMT in glioma is currently being explored. The expression of MGMT gene mainly depends on epigenetic modification–methylation of CpG island of MGMT promoter. CpG island covers a length of 762 bp, with 98 CpG sites located at the 5' end of the gene, ranging from 480 to 1,480 nucleotides. The methylation sites and frequencies of CpG islands vary in MGMT-deficient tumor cell lines, xenografts of glioblastoma and in situ glioblastoma. Methylation in some regions of promoter CpG islands is particularly associated with gene expression. The change in the methylation status of the MGMT promoter after chemotherapy, radiotherapy or both is not completely understood, and results from previous studies have been controversial. Several studies have revealed that chemotherapy may enhance MGMT expression in gliomas. This could be through gene induction or selection of high MGMT-expressing cells during chemotherapy. Selective survival of glioma cells with high MGMT expression during alkylating agent therapy may change MGMT status in case of recurrence. Several strategies have been pursued to improve the anti-tumor effects of temozolomide. These include the synthesis of analogs of O6-meG such as O6-benzylguanine (O6-BG) and O6-(4-bromothenyl) guanine (O6-BTG), RNAi, and viral proteins. This review describes the regulation of MGMT expression and its role in chemotherapy, especially in glioma. Targeting MGMT seems to be a promising approach to overcome chemoresistance. Further studies exploring new agents targeting MGMT with better curative effect and less toxicity are advocated. We anticipate that these developments will improve the current poor prognosis of glioma patients.
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Affiliation(s)
- Wei Yu
- Department of Radiation Oncology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Cancer Institute (Ministry of Education Key Laboratory of Cancer Prevention and Intervention), Zhejiang University Cancer Institute, Hangzhou, China
| | - Lili Zhang
- Department of Radiation Oncology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Cancer Institute (Ministry of Education Key Laboratory of Cancer Prevention and Intervention), Zhejiang University Cancer Institute, Hangzhou, China
| | - Qichun Wei
- Department of Radiation Oncology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Cancer Institute (Ministry of Education Key Laboratory of Cancer Prevention and Intervention), Zhejiang University Cancer Institute, Hangzhou, China
| | - Anwen Shao
- Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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8
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Basu B, Ghosh MK. Extracellular Vesicles in Glioma: From Diagnosis to Therapy. Bioessays 2019; 41:e1800245. [PMID: 31188499 DOI: 10.1002/bies.201800245] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 04/11/2019] [Indexed: 01/08/2023]
Abstract
Increasing evidence indicates that extracellular vesicles (EVs) secreted from tumor cells play a key role in the overall progression of the disease state. EVs such as exosomes are secreted by a wide variety of cells and transport a varied population of proteins, lipids, DNA, and RNA species within the body. Gliomas constitute a significant proportion of all primary brain tumors and majority of brain malignancies. Glioblastoma multiforme (GBM) represents grade IV glioma and is associated with very poor prognosis despite the cumulative advances in diagnostic procedures and treatment strategies. Here, the authors describe the progress in understanding the role of EVs, especially exosomes, in overall glioma progression, and how new research is unraveling the utilities of exosomes in glioma diagnostics and development of next-generation therapeutic systems. Finally, based on an understanding of the latest scientific literature, a model for the possible working of therapeutic exosomes in glioma treatment is proposed.
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Affiliation(s)
- Bhaskar Basu
- Cancer Biology and Inflammatory Disorder Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIR-IICB), TRUE Campus, CN-6, Sector-V, Salt Lake, Kolkata, 700091, & 4, Raja S.C. Mullick Road, Jadavpur, Kolkata, 700032, India
| | - Mrinal K Ghosh
- Cancer Biology and Inflammatory Disorder Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIR-IICB), TRUE Campus, CN-6, Sector-V, Salt Lake, Kolkata, 700091, & 4, Raja S.C. Mullick Road, Jadavpur, Kolkata, 700032, India
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9
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Kaina B, Christmann M. DNA repair in personalized brain cancer therapy with temozolomide and nitrosoureas. DNA Repair (Amst) 2019; 78:128-141. [PMID: 31039537 DOI: 10.1016/j.dnarep.2019.04.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/11/2019] [Accepted: 04/14/2019] [Indexed: 12/16/2022]
Abstract
Alkylating agents have been used since the 60ties in brain cancer chemotherapy. Their target is the DNA and, although the DNA of normal and cancer cells is damaged unselectively, they exert tumor-specific killing effects because of downregulation of some DNA repair activities in cancer cells. Agents exhibiting methylating properties (temozolomide, procarbazine, dacarbazine, streptozotocine) induce at least 12 different DNA lesions. These are repaired by damage reversal mechanisms involving the alkyltransferase MGMT and the alkB homologous protein ALKBH2, and through base excision repair (BER). There is a strong correlation between the MGMT expression level and therapeutic response in high-grade malignant glioma, supporting the notion that O6-methylguanine and, for nitrosoureas, O6-chloroethylguanine are the most relevant toxic damages at therapeutically relevant doses. Since MGMT has a significant impact on the outcome of anti-cancer therapy, it is a predictive marker of the effectiveness of methylating anticancer drugs, and clinical trials are underway aimed at assessing the influence of MGMT inhibition on the therapeutic success. Other DNA repair factors involved in methylating drug resistance are mismatch repair, DNA double-strand break (DSB) repair by homologous recombination (HR) and DSB signaling. Base excision repair and ALKBH2 might also contribute to alkylating drug resistance and their downregulation may have an impact on drug sensitivity notably in cells expressing a high amount of MGMT and at high doses of temozolomide, but the importance in a therapeutic setting remains to be shown. MGMT is frequently downregulated in cancer cells (up to 40% in glioblastomas), which is due to CpG promoter methylation. Astrocytoma (grade III) are frequently mutated in isocitrate dehydrogenase (IDH1). These tumors show a surprisingly good therapeutic response. IDH1 mutation has an impact on ALKBH2 activity thus influencing DNA repair. A master switch between survival and death is p53, which often retains transactivation activity (wildtype) in malignant glioma. The role of p53 in regulating survival via DNA repair and the routes of death are discussed and conclusions as to cancer therapeutic options were drawn.
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Affiliation(s)
- Bernd Kaina
- Institute of Toxicology, University Medical Center Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany.
| | - Markus Christmann
- Institute of Toxicology, University Medical Center Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany
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10
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Kaina B, Izzotti A, Xu J, Christmann M, Pulliero A, Zhao X, Dobreanu M, Au WW. Inherent and toxicant-provoked reduction in DNA repair capacity: A key mechanism for personalized risk assessment, cancer prevention and intervention, and response to therapy. Int J Hyg Environ Health 2018; 221:993-1006. [PMID: 30041861 DOI: 10.1016/j.ijheh.2018.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 07/03/2018] [Accepted: 07/04/2018] [Indexed: 02/05/2023]
Abstract
Genomic investigations reveal novel evidence which indicates that genetic predisposition and inherent drug response are key factors for development of cancer and for poor response to therapy. However, mechanisms for these outcomes and interactions with environmental factors have not been well-characterized. Therefore, cancer risk, prevention, intervention and prognosis determinations have still mainly been based on population, rather than on individualized, evaluations. The objective of this review was to demonstrate that a key mechanism which contributes to the determination is inherent and/or toxicant-provoked reduction in DNA repair capacity. In addition, functional and quantitative determination of DNA repair capacity on an individual basis would dramatically change the evaluation and management of health problems from a population to a personalized basis. In this review, justifications for the scenario were delineated. Topics to be presented include assays for detection of functional DNA repair deficiency, mechanisms for DNA repair defects, toxicant-perturbed DNA repair capacity, epigenetic mechanisms (methylation and miRNA expression) for alteration of DNA repair function, and bioinformatics approach to analyze large amount of genomic data. Information from these topics has recently been and will be used for better understanding of cancer causation and of response to therapeutic interventions. Consequently, innovative genomic- and mechanism-based evidence can be increasingly used to develop more precise cancer risk assessment, and target-specific and personalized medicine.
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Affiliation(s)
| | - Alberto Izzotti
- University of Genoa, Genoa, Italy; IRCCS Policlinico San Martino Genoa, Italy
| | - Jianzhen Xu
- Shantou University Medical College, Shantou, China
| | | | | | - Xing Zhao
- Shantou University Medical College, Shantou, China
| | | | - William W Au
- Shantou University Medical College, Shantou, China; University of Medicine and Pharmacy, Tirgu Mures, Romania; University of Texas Medical Branch, Galveston, TX, USA.
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11
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The specific role of O 6-methylguanine-DNA methyltransferase inhibitors in cancer chemotherapy. Future Med Chem 2018; 10:1971-1996. [PMID: 30001630 DOI: 10.4155/fmc-2018-0069] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The DNA repair protein, O6-methylguanine DNA methyltransferase (MGMT), can confer resistance to guanine O6-alkylating agents. Therefore, inhibition of resistant MGMT protein is a practical approach to increase the anticancer effects of such alkylating agents. Numerous small molecule inhibitors were synthesized and exhibited potential MGMT inhibitory activities. Although they were nontoxic alone, they also inhibited MGMT in normal tissues, thereby enhancing the side effects of chemotherapy. Therefore, strategies for tumor-specific MGMT inhibition have been proposed, including local drug delivery and tumor-activated prodrugs. Over-expression of MGMT in hematopoietic stem cells to protect bone marrow from the toxic effects of chemotherapy is also a feasible selection. The future prospects and challenges of MGMT inhibitors in cancer chemotherapy were also discussed.
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12
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Uptake of glucose-conjugated MGMT inhibitors in cancer cells: role of flippases and type IV P-type ATPases. Sci Rep 2017; 7:13925. [PMID: 29066805 PMCID: PMC5655675 DOI: 10.1038/s41598-017-14129-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 10/06/2017] [Indexed: 01/11/2023] Open
Abstract
The DNA repair protein O6-methylguanine-DNA-methyltransferase (MGMT) is a key determinant of cancer resistance. The MGMT inhibitors O6-benzylguanine (O6BG) and O6-(4-bromothenyl)guanine (O6BTG) failed to enhance the therapeutic response due to toxic side effects when applied in combination with alkylating chemotherapeutics, indicating a need of inhibitor targeting. We assessed MGMT targeting that relies on conjugating the inhibitors O6BG and O6BTG to ß-D-glucose, resulting in O6BG-Glu and O6BTG-Glu, respectively. This targeting strategy was selected by taking advantage of high demand of glucose in cancers. Contrary to our expectation, the uptake of O6BG-Glu and O6BTG-Glu was not dependent on glucose transporters. Instead, it seems that after membrane binding the conjugates are taken up via flippases, which normally transport phospholipids. This membrane binding is the consequence of the amphiphilic character of the conjugates, which at higher concentrations lead to the formation of micelle-like particles in aqueous solution. The unusual uptake mechanism of the conjugates highlights the importance of proper linker selection for a successful ligand-based drug delivery strategy. We also demonstrate that proteins of the P4-Type ATPase family are involved in the transport of the glucose conjugates. The findings are not only important for MGMT inhibitor targeting, but also for other amphiphilic drugs.
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13
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Marsoner T, Schmidt OP, Triemer T, Luedtke NW. DNA-Targeted Inhibition of MGMT. Chembiochem 2017; 18:894-898. [PMID: 28177192 DOI: 10.1002/cbic.201600652] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Indexed: 12/17/2022]
Abstract
The cationic porphyrin 5,10,15,20-tetrakis (diisopropyl-guanidine)-21H,23H-porphine (DIGPor) selectively binds to DNA containing O6 -methylguanine (O6 -MeG) and inhibits the DNA repair enzyme O6 -methylguanine-DNA methyltransferase (MGMT). The O6 -MeG selectivity and MGMT inhibitory activity of DIGPor were improved by incorporating ZnII into the porphyrin. The resulting metal complex (Zn-DIGPor) potentiated the activity of the DNA-alkylating drug temozolomide in an MGMT-expressing cell line. To the best of our knowledge, this is the first example of DNA-targeted MGMT inhibition.
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Affiliation(s)
- Theodor Marsoner
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Olivia P Schmidt
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Therese Triemer
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Nathan W Luedtke
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
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14
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Koyama H, Ikenuma H, Toda H, Kondo G, Hirano M, Kato M, Abe J, Yamada T, Wakabayashi T, Ito K, Natsume A, Suzuki M. Synthesis of PET probe O 6-[(3-[ 11C]methyl)benzyl]guanine by Pd 0-mediated rapid C-[ 11C]methylation toward imaging DNA repair protein O 6-methylguanine-DNA methyltransferase in glioblastoma. Bioorg Med Chem Lett 2017; 27:1892-1896. [PMID: 28363750 DOI: 10.1016/j.bmcl.2017.03.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 02/28/2017] [Accepted: 03/17/2017] [Indexed: 12/31/2022]
Abstract
O6-Benzylguanine (O6-BG) is a substrate of O6-methylguanine-DNA methyltransferase (MGMT), which is involved in drug resistance of chemotherapy in the majority of glioblastoma multiform. For clinical diagnosis, it is hoped that the MGMT expression level could be determined by a noninvasive method to understand the detailed biological properties of MGMT-specific tumors. We synthesized 11C-labeled O6-[(3-methyl)benzyl]guanine ([11C]mMeBG) as a positron emission tomography probe. Thus, a mixed amine-protected stannyl precursor, N9-(tert-butoxycarbonyl)-O6-[3-(tributylstannyl)benzyl]-N2-(trifluoroacetyl)guanine, was subjected to rapid C-[11C]methylation under [11C]CH3I/[Pd2(dba)3]/P(o-CH3C6H4)3/CuCl/K2CO3 in NMP, followed by quick deprotection with LiOH/H2O, giving [11C]mMeBG with total radioactivity of 1.34GBq and ≥99% radiochemical and chemical purities.
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Affiliation(s)
- Hiroko Koyama
- Division of Regeneration and Advanced Medical Science, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu 501-1194, Japan.
| | - Hiroshi Ikenuma
- Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, 7-430 Morioka-cho, Obu-shi, Aichi 474-8511, Japan
| | - Hiroshi Toda
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Goro Kondo
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Masaki Hirano
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Masaya Kato
- Division of Regeneration and Advanced Medical Science, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu 501-1194, Japan
| | - Junichiro Abe
- Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, 7-430 Morioka-cho, Obu-shi, Aichi 474-8511, Japan
| | - Takashi Yamada
- Department of Food and Nutritional Science, College of Bioscience and Biotechnology, Chubu University, Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
| | - Toshihiko Wakabayashi
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Kengo Ito
- Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, 7-430 Morioka-cho, Obu-shi, Aichi 474-8511, Japan
| | - Atsushi Natsume
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
| | - Masaaki Suzuki
- Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, 7-430 Morioka-cho, Obu-shi, Aichi 474-8511, Japan.
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Erasimus H, Gobin M, Niclou S, Van Dyck E. DNA repair mechanisms and their clinical impact in glioblastoma. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2016; 769:19-35. [PMID: 27543314 DOI: 10.1016/j.mrrev.2016.05.005] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 05/04/2016] [Indexed: 12/18/2022]
Abstract
Despite surgical resection and genotoxic treatment with ionizing radiation and the DNA alkylating agent temozolomide, glioblastoma remains one of the most lethal cancers, due in great part to the action of DNA repair mechanisms that drive resistance and tumor relapse. Understanding the molecular details of these mechanisms and identifying potential pharmacological targets have emerged as vital tasks to improve treatment. In this review, we introduce the various cellular systems and animal models that are used in studies of DNA repair in glioblastoma. We summarize recent progress in our knowledge of the pathways and factors involved in the removal of DNA lesions induced by ionizing radiation and temozolomide. We introduce the therapeutic strategies relying on DNA repair inhibitors that are currently being tested in vitro or in clinical trials, and present the challenges raised by drug delivery across the blood brain barrier as well as new opportunities in this field. Finally, we review the genetic and epigenetic alterations that help shape the DNA repair makeup of glioblastoma cells, and discuss their potential therapeutic impact and implications for personalized therapy.
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Affiliation(s)
- Hélène Erasimus
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health (LIH), 84 Val Fleuri, L-1526 Luxembourg, Luxembourg
| | - Matthieu Gobin
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health (LIH), 84 Val Fleuri, L-1526 Luxembourg, Luxembourg
| | - Simone Niclou
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health (LIH), 84 Val Fleuri, L-1526 Luxembourg, Luxembourg
| | - Eric Van Dyck
- NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health (LIH), 84 Val Fleuri, L-1526 Luxembourg, Luxembourg.
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16
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Sun G, Zhang N, Zhao L, Fan T, Zhang S, Zhong R. Synthesis and antitumor activity evaluation of a novel combi-nitrosourea prodrug: Designed to release a DNA cross-linking agent and an inhibitor of O(6)-alkylguanine-DNA alkyltransferase. Bioorg Med Chem 2016; 24:2097-107. [PMID: 27041398 DOI: 10.1016/j.bmc.2016.03.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 03/22/2016] [Accepted: 03/25/2016] [Indexed: 10/22/2022]
Abstract
The drug resistance of CENUs induced by O(6)-alkylguanine-DNA alkyltransferase (AGT), which repairs the O(6)-alkylated guanine and subsequently inhibits the formation of dG-dC cross-links, hinders the application of CENU chemotherapies. Therefore, the discovery of CENU analogs with AGT inhibiting activity is a promising approach leading to novel CENU chemotherapies with high therapeutic index. In this study, a new combi-nitrosourea prodrug 3-(3-(((2-amino-9H-purin-6-yl)oxy)methyl)benzyl)-1-(2-chloroethyl)-1-nitrosourea (6), designed to release a DNA cross-linking agent and an inhibitor of AGT, was synthesized and evaluated for its antitumor activity and ability to induce DNA interstrand cross-links (ICLs). The results indicated that 6 exhibited higher cytotoxicity against mer(+) glioma cells compared with ACNU, BCNU, and their respective combinations with O(6)-benzylguanine (O(6)-BG). Quantifications of dG-dC cross-links induced by 6 were performed using HPLC-ESI-MS/MS. Higher levels of dG-dC cross-link were observed in 6-treated human glioma SF763 cells (mer(+)), whereas lower levels of dG-dC cross-link were observed in 6-treated calf thymus DNA, when compared with the groups treated with BCNU and ACNU. The results suggested that the superiority of 6 might result from the AGT inhibitory moiety, which specifically functions in cells with AGT activity. Molecular docking studies indicated that five hydrogen bonds were formed between the O(6)-BG analogs released from 6 and the five residues in the active pocket of AGT, which provided a reasonable explanation for the higher AGT-inhibitory activity of 6 than O(6)-BG.
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Affiliation(s)
- Guohui Sun
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China
| | - Na Zhang
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China
| | - Lijiao Zhao
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China.
| | - Tengjiao Fan
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China
| | - Shufen Zhang
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China
| | - Rugang Zhong
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China
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Tomaszowski KH, Schirrmacher R, Kaina B. Multidrug Efflux Pumps Attenuate the Effect of MGMT Inhibitors. Mol Pharm 2015; 12:3924-34. [PMID: 26379107 DOI: 10.1021/acs.molpharmaceut.5b00341] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Various mechanisms of drug resistance attenuate the effectiveness of cancer therapeutics, including drug transport and DNA repair. The DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) is a key factor determining the resistance against alkylating anticancer drugs inducing the genotoxic DNA lesions O(6)-methylguanine and O(6)-chloroethylguanine, and MGMT inactivation or depletion renders cells more susceptible to treatment with methylating and chloroethylating agents. Highly specific and efficient inhibitors of the repair protein MGMT were designed, including O(6)-benzylguanine (O(6)BG) and O(6)-(4-bromothenyl)guanine (O(6)BTG) that are nontoxic on their own. Unfortunately, these inhibitors do not select between MGMT in normal and cancer cells, causing nontarget effects in the healthy tissue. Therefore, a targeting strategy for MGMT inhibitors is required. Here, we used O(6)BG and O(6)BTG conjugated to β-d-glucose (O(6)BG-Glu and O(6)BTG-Glu, respectively) in order to selectively inhibit MGMT in tumors, harnessing their high demand for glucose. Both glucose conjugates efficiently inhibited MGMT in several cancer cell lines, but with different extents of sensitization to DNA alkylating agents, with lomustine being more effective than temozolomide. We further show that the glucose conjugates are subject to ATP-binding cassette (ABC) transporter mediated efflux, involving P-glycoprotein, MRP1, and BCRP, which impacts the efficiency of MGMT inhibition. Surprisingly, also O(6)BG and O(6)BTG were subject to an active transport out of the cell. We also show that pharmacological inhibition of efflux transporters increases the induction of cell death following treatment with these MGMT inhibitors and temozolomide. We conclude that strategies of attenuating the efflux by ABC transporters are required for achieving successful MGMT targeting.
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Affiliation(s)
- Karl-Heinz Tomaszowski
- Department of Toxicology, University Medical Center , Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Ralf Schirrmacher
- Montreal Neurological Hospital and Institute , 3801 University Street, Montréal, Quebec H3A 2B4, Canada
| | - Bernd Kaina
- Department of Toxicology, University Medical Center , Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
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18
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Kelley MR, Logsdon D, Fishel ML. Targeting DNA repair pathways for cancer treatment: what's new? Future Oncol 2015; 10:1215-37. [PMID: 24947262 DOI: 10.2217/fon.14.60] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Disruptions in DNA repair pathways predispose cells to accumulating DNA damage. A growing body of evidence indicates that tumors accumulate progressively more mutations in DNA repair proteins as cancers progress. DNA repair mechanisms greatly affect the response to cytotoxic treatments, so understanding those mechanisms and finding ways to turn dysregulated repair processes against themselves to induce tumor death is the goal of all DNA repair inhibition efforts. Inhibition may be direct or indirect. This burgeoning field of research is replete with promise and challenge, as more intricacies of each repair pathway are discovered. In an era of increasing concern about healthcare costs, use of DNA repair inhibitors can prove to be highly effective stewardship of R&D resources and patient expenses.
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Affiliation(s)
- Mark R Kelley
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
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19
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Safdar S, Payne CA, Tu NH, Taite LJ. Targeted nitric oxide delivery preferentially induces glioma cell chemosensitivity via altered p53 and O6-Methylguanine-DNA Methyltransferase activity. Biotechnol Bioeng 2012; 110:1211-20. [DOI: 10.1002/bit.24775] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 08/30/2012] [Accepted: 10/22/2012] [Indexed: 12/30/2022]
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20
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Yao Y, Bilichak A, Golubov A, Kovalchuk I. ddm1 plants are sensitive to methyl methane sulfonate and NaCl stresses and are deficient in DNA repair. PLANT CELL REPORTS 2012; 31:1549-61. [PMID: 22538524 DOI: 10.1007/s00299-012-1269-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 03/28/2012] [Accepted: 04/13/2012] [Indexed: 05/22/2023]
Abstract
UNLABELLED Plant response to stress includes changes in gene expression and chromatin structure. Our previous work showed that Arabidopsis thaliana Dicer-like (DCL) mutants were impaired in transgenerational response to stress that included an increase in recombination frequency, cytosine methylation and stress tolerance. It can be hypothesized that changes in chromatin structure are important for an efficient stress response. To test this hypothesis, we analyzed the stress response of ddm1, a mutant impaired in DDM1, a member of the SWI/SNF family of adenosine triphosphate-dependent chromatin remodeling genes. We exposed Arabidopsis thaliana ddm1 mutants to methyl methane sulfonate (MMS) and NaCl and found that these plants were more sensitive. At the same time, ddm1 plants were similar to wild-type plants in sensitivity to temperature and bleomycin stresses. Direct comparison to met1 plants, deficient in maintenance methyltransferase MET1, showed higher sensitivity of ddm1 plants to NaCl. The level of DNA strand breaks upon exposure to MMS increased in wild-type plants but decreased in ddm1 plants. DNA methylation analysis showed that heterozygous ddm1/DDM1 plants had lower methylation as compared to fourth generation of homozygous ddm1/ddm1 plants. Exposure to MMS resulted in a decrease in methylation in wild-type plants and an increase in ddm1 plants. Finally, in vitro DNA excision repair assay showed lower capacity for ddm1 mutant. Our results provided a new example of a link between genetic genome stability and epigenetic genome stability. KEY MESSAGE We demonstrate that heterozygous ddm1/DDM1 plants are more sensitive to stress and have more severe changes in methylation than homozygous ddm1/ddm1 plants.
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Affiliation(s)
- Youli Yao
- Department of Biological Sciences, University of Lethbridge, University Drive 4401, Lethbridge, AB, T1K 3M4, Canada.
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21
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Bau DT, Lin CC, Chiu CF, Tsai MH. Role of nonhomologous end-joining in oral cancer and personalized pharmacogenomics. Biomedicine (Taipei) 2012. [DOI: 10.1016/j.biomed.2011.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Yang MD, Tsai CW, Chang WS, Tsou YA, Wu CN, Bau DT. Predictive role of XRCC5/ XRCC6 genotypes in digestive system cancers. World J Gastrointest Oncol 2011; 3:175-81. [PMID: 22224172 PMCID: PMC3251741 DOI: 10.4251/wjgo.v3.i12.175] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 10/06/2011] [Accepted: 10/14/2011] [Indexed: 02/05/2023] Open
Abstract
Cancers are a worldwide concern; oral, esophageal and gastrointestinal cancers represent important causes of cancer-related mortality and contribute to a significant burden of human health. The DNA repair systems are the genome caretakers, playing a critical role in the initiation and progression of cancers. However, the association between the genomic variations of DNA repair genes and cancer susceptibility is not well understood. This review focuses on the polymorphic genotypes of the non-homologous end-joining DNA repair system, highlighting the role of two genes of this pathway, XRCC5 and XRCC6, in the susceptibility to digestive system cancers and discussing their potential contributions to personalized medicine.
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Affiliation(s)
- Mei-Due Yang
- Mei-Due Yang, Chia-Wen Tsai, Wen-Shin Chang, Yung-An Tsou, Cheng-Nan Wu, Da-Tian Bau, Terry Fox Cancer Research Laboratory, China Medical University Hospital, 2 Yuh-Der Road, Taichung 40402, Taiwan, China
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23
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Bau DT, Tsai CW, Wu CN. Role of the XRCC5/XRCC6 dimer in carcinogenesis and pharmacogenomics. Pharmacogenomics 2011; 12:515-34. [PMID: 21521024 DOI: 10.2217/pgs.10.209] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Over the past few decades, the incidence of cancer has rapidly increased all over the world and cancer remains a major threat to public health. It is believed that cancer results from a series of genetic alterations that lead to the progressive disorder of the normal mechanisms controlling cell proliferation, differentiation, death and/or genomic stability. The response of the cell to genetic injury and its ability to maintain genomic stability by means of a variety of DNA repair mechanisms are therefore essential in preventing tumor initiation and progression. From the same viewpoint, the relative role of DNA repair as a biomarker for prognosis, predictor of drug and therapy responses or indeed as a target for novel gene therapy, is very promising. In this article, we have summarized the studies investigating the association between the XRCC5/XRCC6 dimer and the susceptibility to multiple cancers and discuss its role in carcinogenesis and its potential application to anticancer drug discovery.
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Affiliation(s)
| | - Chia-Wen Tsai
- Terry Fox Cancer Research Laboratory, China Medical University Hospital, 2 Yuh-Der Road, Taichung, 404 Taiwan, Republic of China
| | - Cheng-Nan Wu
- Terry Fox Cancer Research Laboratory, China Medical University Hospital, 2 Yuh-Der Road, Taichung, 404 Taiwan, Republic of China
- Department of Medical Laboratory Science & Biotechnology, Central-Taiwan University of Science & Technology, Taichung, Taiwan, Republic of China
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24
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KS900: A hypoxia-directed, reductively activated methylating antitumor prodrug that selectively ablates O(6)-alkylguanine-DNA alkyltransferase in neoplastic cells. Biochem Pharmacol 2011; 81:1201-10. [PMID: 21396917 DOI: 10.1016/j.bcp.2011.02.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 02/24/2011] [Accepted: 02/28/2011] [Indexed: 11/22/2022]
Abstract
To most effectively treat cancer it may be necessary to preferentially destroy tumor tissue while sparing normal tissues. One strategy to accomplish this is to selectively cripple the involved tumor resistance mechanisms, thereby allowing the affected anticancer drugs to gain therapeutic efficacy. Such an approach is exemplified by our design and synthesis of the intracellular hypoxic cell activated methylating agent, 1,2-bis(methylsulfonyl)-1-methyl-2-[[1-(4-nitrophenyl)ethoxy]carbonyl]hydrazine (KS900) that targets the O-6 position of guanine in DNA. KS900 is markedly more cytotoxic in clonogenic experiments under conditions of oxygen deficiency than the non-intracellularly activated agents KS90, and 90M, when tested in O(6)-alkylguanine-DNA alkyltransferase (AGT) non-expressing cells (EMT6 mouse mammary carcinoma, CHO/AA8 hamster ovary, and U251 human glioma), and than temozolomide when tested in AGT expressing cells (DU145 human prostate carcinoma). Furthermore, KS900 more efficiently ablates AGT in HL-60 human leukemia and DU145 cells than the spontaneous globally activated methylating agent KS90, with an IC(50) value over 9-fold lower than KS90. Finally, KS900 under oxygen-deficient conditions selectively sensitizes DU145 cells to the chloroethylating agent, onrigin, through the ablation of the resistance protein AGT. Thus, under hypoxia, KS900 is more cytotoxic at substantially lower concentrations than methylating agents such as temozolomide that are not preferentially activated in neoplastic cells by intracellular reductase catalysts. The necessity for intracellular activation of KS900 permits substantially greater cytotoxic activity against cells containing the resistance protein O(6)-alkylguanine-DNA alkyltransferase (AGT) than agents such as temozolomide. Furthermore, the hypoxia-directed intracellular activation of KS900 allows it to preferentially ablate AGT pools under the oxygen-deficient conditions that are present in malignant tissue.
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25
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Apraiz A, Boyano MD, Asumendi A. Cell-centric view of apoptosis and apoptotic cell death-inducing antitumoral strategies. Cancers (Basel) 2011; 3:1042-80. [PMID: 24212653 PMCID: PMC3756403 DOI: 10.3390/cancers3011042] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 02/18/2011] [Accepted: 03/01/2011] [Indexed: 12/14/2022] Open
Abstract
Programmed cell death and especially apoptotic cell death, occurs under physiological conditions and is also desirable under pathological circumstances. However, the more we learn about cellular signaling cascades, the less plausible it becomes to find restricted and well-limited signaling pathways. In this context, an extensive description of pathway-connections is necessary in order to point out the main regulatory molecules as well as to select the most appropriate therapeutic targets. On the other hand, irregularities in programmed cell death pathways often lead to tumor development and cancer-related mortality is projected to continue increasing despite the effort to develop more active and selective antitumoral compounds. In fact, tumor cell plasticity represents a major challenge in chemotherapy and improvement on anticancer therapies seems to rely on appropriate drug combinations. An overview of the current status regarding apoptotic pathways as well as available chemotherapeutic compounds provides a new perspective of possible future anticancer strategies.
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Affiliation(s)
- Aintzane Apraiz
- Department of Cell Biology and Histology, School of Medicine and Dentistry, University of the Basque Country, 48940, Leioa (Bizkaia), Spain.
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26
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Eisele G, Roth P, Hasenbach K, Aulwurm S, Wolpert F, Tabatabai G, Wick W, Weller M. APO010, a synthetic hexameric CD95 ligand, induces human glioma cell death in vitro and in vivo. Neuro Oncol 2010; 13:155-64. [PMID: 21183510 DOI: 10.1093/neuonc/noq176] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Death receptor targeting has emerged as one of the promising novel approaches of cancer therapy. The activation of one such prototypic death receptor, CD95 (Fas/APO-1), has remained controversial because CD95 agonistic molecules have exhibited either too strong toxicity or too little activity. The natural CD95 ligand (CD95L) is a cytokine, which needs to trimerize to mediate a cell death signal. Mega-Fas-Ligand, now referred to as APO010, is a synthetic hexameric CD95 agonist that exhibits strong antitumor activity in various tumor models. Here, we studied the effects of APO010 in human glioma models in vitro and in vivo. Compared with a cross-linked soluble CD95L or a CD95-agonistic antibody, APO010 exhibited superior activity in glioma cell lines expressing CD95 and triggered caspase-dependent cell death. APO010 reduced glioma cell viability in synergy when combined with temozolomide. The locoregional administration of APO010 induced glioma cell death in vivo and prolonged the survival of tumor-bearing mice. A further exploration of APO010 as a novel antiglioma agent is warranted.
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Affiliation(s)
- Günter Eisele
- Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, CH-8091 Zurich, Switzerland.
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27
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Kaina B, Margison GP, Christmann M. Targeting O⁶-methylguanine-DNA methyltransferase with specific inhibitors as a strategy in cancer therapy. Cell Mol Life Sci 2010; 67:3663-81. [PMID: 20717836 PMCID: PMC11115711 DOI: 10.1007/s00018-010-0491-7] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 07/28/2010] [Indexed: 11/29/2022]
Abstract
O (6)-methylguanine-DNA methyltransferase (MGMT) repairs the cancer chemotherapy-relevant DNA adducts, O (6)-methylguanine and O (6)-chloroethylguanine, induced by methylating and chloroethylating anticancer drugs, respectively. These adducts are cytotoxic, and given the overwhelming evidence that MGMT is a key factor in resistance, strategies for inactivating MGMT have been pursued. A number of drugs have been shown to inactivate MGMT in cells, human tumour models and cancer patients, and O (6)-benzylguanine and O (6)-[4-bromothenyl]guanine have been used in clinical trials. While these agents show no side effects per se, they also inactivate MGMT in normal tissues and hence exacerbate the toxic side effects of the alkylating drugs, requiring dose reduction. This might explain why, in any of the reported trials, the outcome has not been improved by their inclusion. It is, however, anticipated that, with the availability of tumour targeting strategies and hematopoetic stem cell protection, MGMT inactivators hold promise for enhancing the effectiveness of alkylating agent chemotherapy.
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Affiliation(s)
- Bernd Kaina
- Institute of Toxicology, University Medical Center, Obere Zahlbacher Str. 67, 55131, Mainz, Germany.
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28
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Addeo R, Caraglia M, De Santi MS, Montella L, Abbruzzese A, Parlato C, Vincenzi B, Carraturo M, Faiola V, Genovese M, Cennamo G, Del Prete S. A new schedule of fotemustine in temozolomide-pretreated patients with relapsing glioblastoma. J Neurooncol 2010; 102:417-24. [PMID: 20694830 PMCID: PMC3089727 DOI: 10.1007/s11060-010-0329-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Accepted: 07/21/2010] [Indexed: 02/08/2023]
Abstract
In the present study we investigated the feasibility and effectiveness of a new biweekly schedule of fotemustine (FTM) in patients with recurrent glioblastoma, after at least one previous treatment. The primary endpoint was progression-free survival at 6 months; secondary objectives were clinical response, overall survival, disease-free survival, and toxicity. Forty patients (median age 52.8 years; median Karnofsky Performance Status at progression 90) underwent second-line chemotherapy with FTM. Selected patients were previously treated with a standard radiotherapy course with concomitant temozolomide (TMZ). After tumor relapse or progression proven by magnetic resonance imaging (MRI), all patients underwent chemotherapy with FTM, given intravenously at dose of 80 mg/m2 every 2 weeks for five consecutive administrations (induction phase), and then every 3 weeks at 100 mg/m2 as maintenance. A total of 329 infusions were administered; the median number of cycles administered was 8. All patients completed the induction phase, and 29 patients received at least one maintenance infusion. Response to treatment was assessed using MacDonald criteria. One complete response [2.5%, 95% confidence interval (CI): 0–10%], 9 partial responses (22.5%, 95% CI: 15–37%), and 16 stable diseases (40%, 95% CI: 32–51%) were observed. Median time to progression was 6.7 months (95% CI: 3.9–9.1 months). Progression-free survival at 6 months was 61%. Median survival from beginning of FTM chemotherapy was 11.1 months. The schedule was generally well tolerated; the main toxicities were hematologic (grade 3 thrombocytopenia in two cases). To the best of our knowledge, this is the first report specifically dealing with the use of a biweekly induction schedule of FTM. The study demonstrates that FTM has therapeutic efficacy as single-drug second-line chemotherapy with a favorable safety profile.
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Affiliation(s)
- Raffaele Addeo
- Oncology Department, "S. Giovanni di Dio" Hospital, ASL Napoli2 Nord Via Giovanni XXIII, 80028 Frattaminore, Naples, Italy.
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29
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Ristić-Fira AM, Korićanac LB, Zakula JJ, Valastro LM, Iannolo G, Privitera G, Cuttone G, Petrović IM. Effects of fotemustine or dacarbasine on a melanoma cell line pretreated with therapeutic proton irradiation. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2009; 28:50. [PMID: 19358719 PMCID: PMC2672057 DOI: 10.1186/1756-9966-28-50] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 04/09/2009] [Indexed: 01/30/2023]
Abstract
Background Considering that HTB140 melanoma cells have shown a poor response to either protons or alkylating agents, the effects of a combined use of these agents have been analysed. Methods Cells were irradiated in the middle of the therapeutic 62 MeV proton spread out Bragg peak (SOBP). Irradiation doses were 12 or 16 Gy and are those frequently used in proton therapy. Four days after irradiation cells were treated with fotemustine (FM) or dacarbazine (DTIC). Drug concentrations were 100 and 250 μM, values close to those that produce 50% of growth inhibition. Cell viability, proliferation, survival and cell cycle distribution were assessed 7 days after irradiation that corresponds to more than six doubling times of HTB140 cells. In this way incubation periods providing the best single effects of drugs (3 days) and protons (7 days) coincided at the same time. Results Single proton irradiations have reduced the number of cells to ~50%. FM caused stronger cell inactivation due to its high toxicity, while the effectiveness of DTIC, that was important at short term, almost vanished with the incubation of 7 days. Cellular mechanisms triggered by proton irradiation differently influenced the final effects of combined treatments. Combination of protons and FM did not improve cell inactivation level achieved by single treatments. A low efficiency of the single DTIC treatment was overcome when DTIC was introduced following proton irradiation, giving better inhibitory effects with respect to the single treatments. Most of the analysed cells were in G1/S phase, viable, active and able to replicate DNA. Conclusion The obtained results are the consequence of a high resistance of HTB140 melanoma cells to protons and/or drugs. The inactivation level of the HTB140 human melanoma cells after protons, FM or DTIC treatments was not enhanced by their combined application.
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Ridolfi L, Fiorentini G, Guida M, Michiara M, Freschi A, Aitini E, Ballardini M, Bichisao E, Ridolfi R. Multicentre, open, noncomparative Phase II trial to evaluate the efficacy and tolerability of fotemustine, cisplatin, alpha-interferon and interleukin-2 in advanced melanoma patients. Melanoma Res 2009; 19:100-5. [DOI: 10.1097/cmr.0b013e328328f7ec] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Treatment of recurrent malignant gliomas with fotemustine monotherapy: impact of dose and correlation with MGMT promoter methylation. BMC Cancer 2009; 9:101. [PMID: 19335893 PMCID: PMC2667532 DOI: 10.1186/1471-2407-9-101] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Accepted: 03/31/2009] [Indexed: 12/02/2022] Open
Abstract
Background In recurrent malignant gliomas (MGs), a high rate of haematological toxicity is observed with the use of fotemustine at the conventional schedule (100 mg/m2 weekly for 3 consecutive weeks followed by triweekly administration after a 5-week rest period). Also, the impact of O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status on fotemustine activity has never been explored in the clinical setting. Methods 40 patients with recurrent pretreated MG were identified as being treated with fotemustine at doses ranging from 65 mg/m2 to 100 mg/m2. Patients were classified into 3 groups according to the dose of fotemustine received, from the lowest dosage received in group A, to the highest in group C. Analysis of MGMT promoter methylation in tumor tissue was successfully performed in 19 patients. Results Overall, 20% of patients responded to treatment, for a disease control rate (DCR, responses plus stabilizations) of 47.5%. Groups A and B experienced a response rate of 40% and 26.5% respectively, while the corresponding value for group C was 10%. Out of 19 patients, MGMT promoter was found methylated in 12 cases among which a DCR of 66.5% was observed. All 7 patients with unmethylated MGMT promoter were progressive to fotemustine. Conclusion Low-dose fotemustine at 65–75 mg/m2 (induction phase) followed by 75–85 mg/m2 (maintenance phase) has an activity comparable to that of the conventional schedule. By determination of the MGMT promoter methylation status patients might be identified who are more likely to benefit from fotemustine chemotherapy.
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Ristić-Fira AM, Petrović IM, Korićanac LB, Valastro LM, Privitera G, Cuttone G. Assessment of the inhibitory effects of different radiation qualities or chemotherapeutic agents on a human melanoma cell line. Phys Med 2008; 24:187-95. [DOI: 10.1016/j.ejmp.2008.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 03/07/2008] [Accepted: 04/16/2008] [Indexed: 11/17/2022] Open
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Kitange GJ, Carlson BL, Schroeder MA, Grogan PT, Lamont JD, Decker PA, Wu W, James CD, Sarkaria JN. Induction of MGMT expression is associated with temozolomide resistance in glioblastoma xenografts. Neuro Oncol 2008; 11:281-91. [PMID: 18952979 DOI: 10.1215/15228517-2008-090] [Citation(s) in RCA: 257] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Temozolomide (TMZ)-based therapy is the standard of care for patients with glioblastoma multiforme (GBM), and resistance to this drug in GBM is modulated by the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT). Expression of MGMT is silenced by promoter methylation in approximately half of GBM tumors, and clinical studies have shown that elevated MGMT protein levels or lack of MGMT promoter methylation is associated with TMZ resistance in some, but not all, GBM tumors. In this study, the relationship between MGMT protein expression and tumor response to TMZ was evaluated in four GBM xenograft lines that had been established from patient specimens and maintained by serial subcutaneous passaging in nude mice. Three MGMT unmethylated tumors displayed elevated basal MGMT protein expression, but only two of these were resistant to TMZ therapy (tumors GBM43 and GBM44), while the other (GBM14) displayed a level of TMZ sensitivity that was similar in extent to that seen in a single MGMT hypermethylated line (GBM12). In tissue culture and animal studies, TMZ treatment resulted in robust and prolonged induction of MGMT expression in the resistant GBM43 and GBM44 xenograft lines, while MGMT induction was blunted and abbreviated in GBM14. Consistent with a functional significance of MGMT induction, treatment of GBM43 with a protracted low-dose TMZ regimen was significantly less effective than a shorter high-dose regimen, while survival for GBM14 was improved with the protracted dosing regimen. In conclusion, MGMT expression is dynamically regulated in some MGMT nonmethylated tumors, and in these tumors, protracted dosing regimens may not be effective.
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Affiliation(s)
- Gaspar J Kitange
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA
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Kelley MR, Fishel ML. DNA repair proteins as molecular targets for cancer therapeutics. Anticancer Agents Med Chem 2008; 8:417-25. [PMID: 18473726 DOI: 10.2174/187152008784220294] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cancer therapeutics include an ever-increasing array of tools at the disposal of clinicians in their treatment of this disease. However, cancer is a tough opponent in this battle and current treatments which typically include radiotherapy, chemotherapy and surgery are not often enough to rid the patient of his or her cancer. Cancer cells can become resistant to the treatments directed at them and overcoming this drug resistance is an important research focus. Additionally, increasing discussion and research is centering on targeted and individualized therapy. While a number of approaches have undergone intensive and close scrutiny as potential approaches to treat and kill cancer (signaling pathways, multidrug resistance, cell cycle checkpoints, anti-angiogenesis, etc.), much less work has focused on blocking the ability of a cancer cell to recognize and repair the damaged DNA which primarily results from the front line cancer treatments; chemotherapy and radiation. More recent studies on a number of DNA repair targets have produced proof-of-concept results showing that selective targeting of these DNA repair enzymes has the potential to enhance and augment the currently used chemotherapeutic agents and radiation as well as overcoming drug resistance. Some of the targets identified result in the development of effective single-agent anti-tumor molecules. While it is inherently convoluted to think that inhibiting DNA repair processes would be a likely approach to kill cancer cells, careful identification of specific DNA repair proteins is increasingly appearing to be a viable approach in the cancer therapeutic cache.
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Affiliation(s)
- Mark R Kelley
- Department of Pediatrics, Section of Hematology/Oncology, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 W Walnut St. R4-W302C, Indianapolis, IN 46202, USA.
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Rapp M, Maurizis JC, Papon J, Labarre P, Wu TD, Croisy A, Guerquin-Kern JL, Madelmont JC, Mounetou E. A New O6-Alkylguanine-DNA Alkyltransferase Inhibitor Associated with a Nitrosourea (Cystemustine) Validates a Strategy of Melanoma-Targeted Therapy in Murine B16 and Human-Resistant M4Beu Melanoma Xenograft Models. J Pharmacol Exp Ther 2008; 326:171-7. [DOI: 10.1124/jpet.108.137737] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Tubbs JL, Pegg AE, Tainer JA. DNA binding, nucleotide flipping, and the helix-turn-helix motif in base repair by O6-alkylguanine-DNA alkyltransferase and its implications for cancer chemotherapy. DNA Repair (Amst) 2007; 6:1100-15. [PMID: 17485252 PMCID: PMC1993358 DOI: 10.1016/j.dnarep.2007.03.011] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
O(6)-Alkylguanine-DNA alkyltransferase (AGT) is a crucial target both for the prevention of cancer and for chemotherapy, since it repairs mutagenic lesions in DNA, and it limits the effectiveness of alkylating chemotherapies. AGT catalyzes the unique, single-step, direct damage reversal repair of O(6)-alkylguanines by selectively transferring the O(6)-alkyl adduct to an internal cysteine residue. Recent crystal structures of human AGT alone and in complex with substrate DNA reveal a two-domain alpha/beta fold and a bound zinc ion. AGT uses its helix-turn-helix motif to bind substrate DNA via the minor groove. The alkylated guanine is then flipped out from the base stack into the AGT active site for repair by covalent transfer of the alkyl adduct to Cys145. An asparagine hinge (Asn137) couples the helix-turn-helix DNA binding and active site motifs. An arginine finger (Arg128) stabilizes the extrahelical DNA conformation. With this newly improved structural understanding of AGT and its interactions with biologically relevant substrates, we can now begin to unravel the role it plays in preserving genetic integrity and discover how it promotes resistance to anticancer therapies.
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Affiliation(s)
- Julie L. Tubbs
- The Scripps Research Institute, The Skaggs Institute for Chemical Biology and Department of Molecular Biology, 10550 North Torrey Pines Road, MB4, La Jolla, CA 92037
| | - Anthony E. Pegg
- Department of Cellular and Molecular Physiology, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - John A. Tainer
- The Scripps Research Institute, The Skaggs Institute for Chemical Biology and Department of Molecular Biology, 10550 North Torrey Pines Road, MB4, La Jolla, CA 92037
- Life Sciences Division, Department of Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- *To whom correspondence should be addressed: Tel: +1-858-784-8119; fax: +1-858-784-2289;
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Kaina B, Christmann M, Naumann S, Roos WP. MGMT: key node in the battle against genotoxicity, carcinogenicity and apoptosis induced by alkylating agents. DNA Repair (Amst) 2007; 6:1079-99. [PMID: 17485253 DOI: 10.1016/j.dnarep.2007.03.008] [Citation(s) in RCA: 444] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
O(6)-methylguanine-DNA methyltransferase (MGMT) plays a crucial role in the defense against alkylating agents that generate, among other lesions, O(6)-alkylguanine in DNA (collectively termed O(6)-alkylating agents [O(6)AA]). The defense is highly important, since O(6)AA are common environmental carcinogens, are formed endogenously during normal cellular metabolism and possibly inflammation, and are being used in cancer therapy. O(6)AA induced DNA damage is subject to repair, which is executed by MGMT, AlkB homologous proteins (ABH) and base excision repair (BER). Although this review focuses on MGMT, the mechanism of repair by ABH and BER will also be discussed. Experimental systems, in which MGMT has been modulated, revealed that O(6)-methylguanine (O(6)MeG) and O(6)-chloroethylguanine are major mutagenic, carcinogenic, recombinogenic, clastogenic and killing lesions. O(6)MeG-induced clastogenicity and cell death require MutS alpha-dependent mismatch repair (MMR), whereas O(6)-chloroethylguanine-induced killing occurs independently of MMR. Extensive DNA replication is required for O(6)MeG to provoke cytotoxicity. In MGMT depleted cells, O(6)MeG induces apoptosis almost exclusively, barely any necrosis, which is presumably due to the remarkable ability of secondarily formed DNA double-strand breaks (DSBs) to trigger apoptosis via ATM/ATR, Chk1, Chk2, p53 and p73. Depending on the cellular background, O(6)MeG activates both the death receptor and the mitochondrial apoptotic pathway. The inter-individual expression of MGMT in human lymphocytes is highly variable. Given the key role of MGMT in cellular defense, determination of MGMT activity could be useful for assessing a patient's drug sensitivity. MGMT is expressed at highly variable amounts in human tumors. In gliomas, a correlation was found between MGMT activity, MGMT promoter methylation and response to O(6)AA. Although the human MGMT gene is inducible by glucocorticoids and genotoxins such as radiation and alkylating agents, the role of this induction in the protection against carcinogens and the development of chemotherapeutic alkylating drug resistance are still unclear. Modulation of MGMT expression in tumors and normal tissue is currently being investigated as a possible strategy for improving cancer therapy.
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Affiliation(s)
- Bernd Kaina
- Department of Toxicology, University of Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany.
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Juillerat A, Juillerat-Jeanneret L. S-alkylthiolation of O6-methylguanine-DNA-methyltransferase (MGMT) to sensitize cancer cells to anticancer therapy. Expert Opin Ther Targets 2007; 11:349-61. [PMID: 17298293 DOI: 10.1517/14728222.11.3.349] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
O6-methylguanine DNA methyltransferase/O6-alkylguanine DNA alkyltransferase (MGMT/AGT) removes alkyl adducts from the O6-position of guanine in DNA. Expression of MGMT in human cancers has been associated with resistance to therapies using alkylating agents. MGMT promoter methylation regulates its expression and response to alkylating agents. A combination of O6-benzylguanine-based inhibitors of MGMT with alkylating agents improved the efficacy. However, this is associated with enhanced cytotoxicity and the induction of GC to AT transition mutations presumably also in progenitor/stem cells. A few recent studies have described analogs of O6-benzylguanine targeting defined pathways of cancer cells that can be used to improve the selectivity of O6-benzylguanine-based inhibitors for cancer cells. Therefore, MGMT inhibitor targeting represents a reliable strategy for improving cancer therapy with alkylating agents.
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Affiliation(s)
- Alexandre Juillerat
- Institute of Chemical Sciences and Engineering, Swiss Institute of Technology of Lausanne (EPFL), Lausanne, Switzerland
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Koch D, Hundsberger T, Boor S, Kaina B. Local intracerebral administration of O(6)-benzylguanine combined with systemic chemotherapy with temozolomide of a patient suffering from a recurrent glioblastoma. J Neurooncol 2006; 82:85-9. [PMID: 17031555 DOI: 10.1007/s11060-006-9244-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Accepted: 08/09/2006] [Indexed: 10/24/2022]
Abstract
The DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) is a major determinant of methylating anticancer drug resistance. Inactivation of MGMT by pseudosubstrate inhibitors, such as O(6)-benzylguanine (O(6)BG), sensitizes tumor cells to O(6)-alkylating agents. However, systemic administration of O(6)BG causes depletion of MGMT in all tissues of the body. Therefore, dose reduction of O(6)-alkylating drugs administered together with O(6)BG is required in order to avoid unwished toxic side effects. To attenuate the increased systemic toxicity caused by MGMT inhibitors, local MGMT inactivation would be desirable. Here, we report on intracerebral treatment with O(6)BG of a patient suffering from glioblastoma. O(6)BG was administered weekly in the tumor cavity by means of an Ommaya reservoir. This application was well tolerated. Concomitant treatment with temozolomide (Temodal) was associated with transient tumor stabilization without detectable side effects. Although evidence is still lacking that local O(6)BG administration caused MGMT to be depleted in the residual tumor, the trial shows that intracerebral treatment with O(6)BG is feasible. It might be a safe strategy for improving glioma therapy by treatment with temozolomide (and presumably also other O(6)-alkylating drugs) concomitant with O(6)BG without augmenting drug-induced systemic side effects.
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Affiliation(s)
- Dorothee Koch
- Department of Neurosurgery, University of Mainz, Langenbeckstr 1, 55131, Mainz, Germany.
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Abstract
Chemotherapy and radiation are two important modalities for cancer treatment. Many agents in clinical used have the ability to induce DNA damage, however they may be highly cytotoxic as a secondary effect. Different mechanisms are involved both, in detection and repair of DNA damage. The modulation of these pathways, has a great impact on clinical outcome and is frequently responsible of therapeutic resistance. Therefore, pharmacological inhibition of DNA damage repair pathways has been explored as a useful strategy to enhance chemo and radiosensitivity, thus it could be used for reversing drug resistance. Different agents have shown excellent results in preclinical studies in combination with radiation or chemotherapy. Early phase clinical trials are now being carried out using different DNA repair inhibitors targeting several enzymes such as PARP, DNA-PK or MGMT.
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Affiliation(s)
- Isabel Sánchez-Pérez
- Instituto de Investigaciones Biomédicas del CSIC/UAM, Traslational Oncology Unit CSIC/Hospital La Paz, Madrid, Spain.
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Ding J, Miao ZH, Meng LH, Geng MY. Emerging cancer therapeutic opportunities target DNA-repair systems. Trends Pharmacol Sci 2006; 27:338-44. [PMID: 16697054 DOI: 10.1016/j.tips.2006.04.007] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Revised: 03/07/2006] [Accepted: 04/24/2006] [Indexed: 12/18/2022]
Abstract
DNA-damaging agents have a central role in non-surgical cancer treatment. The balance between DNA damage and repair determines the final therapeutic consequences. An elevated DNA-repair capacity in tumor cells leads to drug or radiation resistance and severely limits the efficacy of these agents. Interference with DNA repair has emerged as an important approach in combination therapy against cancer. Anticancer targets in DNA-repair systems have emerged, against which several small-molecule compounds are currently undergoing clinical trials.
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Affiliation(s)
- Jian Ding
- Division of Antitumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China.
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Gajewski TF, Sosman J, Gerson SL, Liu L, Dolan E, Lin S, Vokes EE. Phase II trial of the O6-alkylguanine DNA alkyltransferase inhibitor O6-benzylguanine and 1,3-bis(2-chloroethyl)-1-nitrosourea in advanced melanoma. Clin Cancer Res 2006; 11:7861-5. [PMID: 16278409 DOI: 10.1158/1078-0432.ccr-05-0060] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE 1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU) induces DNA damage via a chloroethyl adduct at the O(6) position of guanine, which can be repaired by O(6)-alkylguanine DNA alkyltransferase (AGT) expressed in melanoma. We postulated that the addition of O(6) benzylguanine (O(6)BG), a potent inactivator of AGT, would improve the clinical response to BCNU in melanoma. EXPERIMENTAL DESIGN Patients had measurable disease, adequate organ function, and a corrected Diffusing capacity of the lung for carbon monoxide (DLCO) of > or =70% predicted. They were accrued into two cohorts based on prior chemotherapy. O(6)BG (120 mg/m(2)) was administered i.v. followed by BCNU (40 mg/m(2)) on an outpatient basis. Peripheral blood mononuclear cells (PBMC) were collected pre- and 18 hours post-O(6)BG to analyze AGT depletion. Treatment was every 6 weeks, and clinical response was assessed after every two cycles. RESULTS Forty-two patients were enrolled, 22 of these patients were chemotherapy-naïve. In the chemotherapy-naïve cohort, there was a patient with a complete response (CR), 4 with stable disease (SD), 13 with progressive disease (PD), and 4 nonevaluable patients; the median time to progression was 80 days and the median survival was 211 days. In the prior-chemotherapy cohort, there were no responses, 3 SD, 15 PD, and 2 nonevaluable patients; median time to progression was 54 days and median survival was 120 days. AGT was depleted from PBMC in the 15 patients tested. Grades 3 to 4 myelosuppression was seen in 57% of patients; toxicities were similar between the two cohorts. CONCLUSIONS O(6)BG/BCNU was successfully administered on an outpatient basis and depleted AGT from PBMC. However, significant myelosuppression was observed and the clinical outcome was not improved. Alternative mechanisms of resistance to melanoma cell death need to be investigated.
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Affiliation(s)
- Yukiko Mishina
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637
| | - Erica M. Duguid
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637
| | - Chuan He
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637
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Hermisson M, Klumpp A, Wick W, Wischhusen J, Nagel G, Roos W, Kaina B, Weller M. O6-methylguanine DNA methyltransferase and p53 status predict temozolomide sensitivity in human malignant glioma cells. J Neurochem 2006; 96:766-76. [PMID: 16405512 DOI: 10.1111/j.1471-4159.2005.03583.x] [Citation(s) in RCA: 244] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Temozolomide (TMZ) is a methylating agent which prolongs survival when administered during and after radiotherapy in the first-line treatment of glioblastoma and which also has significant activity in recurrent disease. O6-methylguanine DNA methyltransferase (MGMT) is a DNA repair enzyme attributed a role in cancer cell resistance to O6-alkylating agent-based chemotherapy. Using a panel of 12 human glioma cell lines, we here defined the sensitivity to TMZ in acute cytotoxicity and clonogenic survival assays in relation to MGMT, mismatch repair and p53 status and its modulation by dexamethasone, irradiation and BCL-X(L). We found that the levels of MGMT expression were a major predictor of TMZ sensitivity in human glioma cells. MGMT activity and clonogenic survival after TMZ exposure are highly correlated (p < 0.0001, r2 = 0.92). In contrast, clonogenic survival after TMZ exposure does not correlate with the expression levels of the mismatch repair proteins mutS homologue 2, mutS homologue 6 or post-meiotic segregation increased 2. The MGMT inhibitor O6-benzylguanine sensitizes MGMT-positive glioma cells to TMZ whereas MGMT gene transfer into MGMT-negative cells confers protection. The antiapoptotic BCL-X(L) protein attenuates TMZ cytotoxicity in MGMT-negative LNT-229 but not in MGMT-positive LN-18 cells. Neither ionizing radiation (4 Gy) nor clinically relevant concentrations of dexamethasone modulate MGMT activity or TMZ sensitivity. Abrogation of p53 wild-type function strongly attenuates TMZ cytotoxicity. Conversely, p53 mimetic agents designed to stabilize the wild-type conformation of p53 sensitize glioma cells for TMZ cytotoxicity. Collectively, these results suggest that the determination of MGMT expression and p53 status will help to identify glioma patients who will or will not respond to TMZ.
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Affiliation(s)
- Mirjam Hermisson
- Laboratory of Molecular Neuro-Oncology, Department of General Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, School of Medicine, Tübingen, Germany.
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Mühlhausen U, Schirrmacher R, Piel M, Lecher B, Briegert M, Piee-Staffa A, Kaina B, Rösch F. Synthesis of 131I-Labeled Glucose-Conjugated Inhibitors of O6-Methylguanine-DNA Methyltransferase (MGMT) and Comparison with Nonconjugated Inhibitors as Potential Tools for in Vivo MGMT Imaging. J Med Chem 2005; 49:263-72. [PMID: 16392811 DOI: 10.1021/jm050588q] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
O(6)-Substituted guanine derivatives are powerful agents used for tumor cell sensitization by inhibition of the DNA repair enzyme O(6)-methylguanine-DNA methyltransferase (MGMT). To provide targeted accumulation of MGMT inhibitors in tumor tissue as well as tools for in vivo imaging, we synthesized iodinated C(8)-alkyl-linked glucose conjugates of 2-amino-6-(5-iodothenyl)-9H-purine (O(6)-(5-iodothenyl) guanine, ITG) and 2-amino-6-(3-iodobenzyloxy)-9H-purine (O(6)-(5-iodobenzyl) guanine, IBG). These compounds have MGMT inhibitor constants (IC(50) values) of 0.8 and 0.45 microM for ITGG and IBGG, respectively, as determined in HeLa S3 cells after 2-h incubation with inhibitor. To substantiate that the (131)I-(hetero)arylmethylene group at the O(6)-position of guanine is transferred to MGMT, both the glucose conjugated inhibitors ITGG and IBGG and the corresponding nonglucose conjugated compounds ITG and IBG were labeled with iodine-131. The radioiodinations of all compounds with [(131)I]I(-) were performed with radiochemical yields of >70% for the destannylation of the corresponding tri-n-butylstannylated precursors. The binding ability of [(131)I]ITGG, [(131)]IBGG, [(131)I]ITG, and [(131)I]IBG to purified MGMT was tested. All radioactive compounds were substrates for MGMT, as demonstrated using a competitive repair assay. The newly synthesized radioactive inhibitors were utilized to study ex vivo biodistribution in mice, and the tumor-to-blood ratio of tissue uptake of [(131)I]IBG and [(131)I]IBGG was determined to be 0.24 and 0.76 after 0.5 h, respectively.
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Affiliation(s)
- Ute Mühlhausen
- Institute of Nuclear Chemistry, University of Mainz, Germany
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Abstract
The same doses of medication cause considerable heterogeneity in efficacy and toxicity across human populations. Genetic factors are thought to represent important determinants of drug efficacy and toxicity. Pharmacogenetics focuses on the prediction of the response of tumor and normal tissue to standard therapy by genetic profiling and, thereby, to select the most appropriate medication at optimal doses for each individual patient. In the present review, we discuss the relevance of single nucleotide polymorphisms (SNP) in genes, whose gene products act upstream of the actual drug target sites, that is, drug transporters and drug metabolizing phase I and II enzymes, or downstream of them, that is, apoptosis-regulating genes and chemokines. SNPs in relevant genes, which encode for proteins that interact with anticancer drugs, were also considered, that is, enzymes of DNA biosynthesis and metabolism, DNA repair enzymes, and proteins of the mitotic spindle. A significant body of evidence supports the concept of predicting drug efficacy and toxicity by SNP genotyping. As the efficacy of cancer chemotherapy, as well as the drug-related toxicity in normal tissues is multifactorial in nature, sophisticated approaches such as genome-wide linkage analyses and integrate drug pathway profiling may improve the predictive power compared with genotyping of single genes. The implementation of pharmacogenetics into clinical routine diagnostics including genotype-based recommendations for treatment decisions and risk assessment for practitioners represents a challenge for the future.
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Affiliation(s)
- Thomas Efferth
- German Cancer Research Center, M070, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
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