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Yoshida K, Ogawa S. Splicing factor mutations and cancer. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:445-59. [PMID: 24523246 DOI: 10.1002/wrna.1222] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/09/2014] [Accepted: 01/13/2014] [Indexed: 12/11/2022]
Abstract
Recent advances in high-throughput sequencing technologies have unexpectedly revealed that somatic mutations of splicing factor genes frequently occurred in several types of hematological malignancies, including myelodysplastic syndromes, other myeloid neoplasms, and chronic lymphocytic leukemia. Splicing factor mutations have also been reported in solid cancers such as breast and pancreatic cancers, uveal melanomas, and lung adenocarcinomas. These mutations were heterozygous and mainly affected U2AF1 (U2AF35), SRSF2 (SC35), SF3B1 (SF3B155 or SAP155), and ZRSR2 (URP), which are engaged in the initial steps of RNA splicing, including 3' splice-site recognition, and occur in a large mutually exclusive pattern, suggesting a common impact of these mutations on RNA splicing. In this study, splicing factor mutations in various types of cancers, their functional/biological effects, and their potential as therapeutic targets have been reviewed.
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Affiliation(s)
- Kenichi Yoshida
- Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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102
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Chen B, Akash MSH, Rehman K, Sun H, Chen S. Expression and bioactivity analysis of staphylococcal enterotoxin G and staphylococcal enterotoxin I. PHARMACEUTICAL BIOLOGY 2014; 52:8-13. [PMID: 23915110 DOI: 10.3109/13880209.2013.804845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
CONTEXT The filtrate of Staphylococcus aureus culture, named staphylococcal enterotoxin C injection, has been used for 10 years in China. SEC2 has been claimed to be the only staphylococcal enterotoxins (SEs) without certifiable evidence. OBJECTIVES To present an efficient procedure for the expression and purification of recombinant proteins SEG and SEI, from S. aureus. MATERIALS AND METHODS In present work, we extracted total DNA from S. aureus (FRI 1230) and the recombinant proteins of SEG and SEI were then cloned, expressed and purified using E. coli. Splenic lymphocytes were used as effector cells and K562 and B16 cells were used as target cells to evaluate the inhibitory and stimulatory abilities of purified rSEG and rSEI on in vitro proliferation. RESULTS The size of amplified products of SEG and SEI genes were found to be about 400 and 467 bp, respectively. pGEX-SEG and pGEX-SEI were constructed successfully. SEG and SEI were demonstrated to be active stimulators of T-cell proliferation; moreover, they inhibited the proliferation of K562 cells and B16 cells. DISCUSSION The current findings suggest that SEC2 might not be the only active component of staphylococcal enterotoxin C injection and may involve other essential proteins like SEG and SEI in its clinical efficacy. CONCLUSION This efficient procedure for the expression and purification of SEG and SEI and may be useful for mass production of therapeutically important proteins. In the future, proteins acting as active stimulators of T-cell proliferation may help in developing effective cancer therapy.
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Affiliation(s)
- Bin Chen
- Tongji Medical College, Huazhong University of Science and Technology , Wuhan, Hubei , China
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103
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Sankunny M, Parikh RA, Lewis DW, Gooding WE, Saunders WS, Gollin SM. Targeted inhibition of ATR or CHEK1 reverses radioresistance in oral squamous cell carcinoma cells with distal chromosome arm 11q loss. Genes Chromosomes Cancer 2013; 53:129-43. [PMID: 24327542 DOI: 10.1002/gcc.22125] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 10/14/2013] [Accepted: 10/15/2013] [Indexed: 01/08/2023] Open
Abstract
Oral squamous cell carcinoma (OSCC), a subset of head and neck squamous cell carcinoma (HNSCC), is the eighth most common cancer in the U.S.. Amplification of chromosomal band 11q13 and its association with poor prognosis has been well established in OSCC. The first step in the breakage-fusion-bridge (BFB) cycle leading to 11q13 amplification involves breakage and loss of distal 11q. Distal 11q loss marked by copy number loss of the ATM gene is observed in 25% of all Cancer Genome Atlas (TCGA) tumors, including 48% of HNSCC. We showed previously that copy number loss of distal 11q is associated with decreased sensitivity (increased resistance) to ionizing radiation (IR) in OSCC cell lines. We hypothesized that this radioresistance phenotype associated with ATM copy number loss results from upregulation of the compensatory ATR-CHEK1 pathway, and that knocking down the ATR-CHEK1 pathway increases the sensitivity to IR of OSCC cells with distal 11q loss. Clonogenic survival assays confirmed the association between reduced sensitivity to IR in OSCC cell lines and distal 11q loss. Gene and protein expression studies revealed upregulation of the ATR-CHEK1 pathway and flow cytometry showed G2 M checkpoint arrest after IR treatment of cell lines with distal 11q loss. Targeted knockdown of the ATR-CHEK1 pathway using CHEK1 or ATR siRNA or a CHEK1 small molecule inhibitor (SMI, PF-00477736) resulted in increased sensitivity of the tumor cells to IR. Our results suggest that distal 11q loss is a useful biomarker in OSCC for radioresistance that can be reversed by ATR-CHEK1 pathway inhibition.
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Affiliation(s)
- Madhav Sankunny
- Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA; University of Pittsburgh Cancer Institute, Pittsburgh, PA
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104
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Millard M, Gallagher JD, Olenyuk BZ, Neamati N. A selective mitochondrial-targeted chlorambucil with remarkable cytotoxicity in breast and pancreatic cancers. J Med Chem 2013; 56:9170-9. [PMID: 24147900 DOI: 10.1021/jm4012438] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitrogen mustards, widely used as chemotherapeutics, have limited safety and efficacy. Mitochondria lack a functional nucleotide excision repair mechanism to repair DNA adducts and are sensitive to alkylating agents. Importantly, cancer cells have higher intrinsic mitochondrial membrane potential (Δψmt) than normal cells. Therefore, selectively targeting nitrogen mustards to cancer cell mitochondria based on Δψmt could overcome those limitations. Herein, we describe the design, synthesis, and evaluation of Mito-Chlor, a triphenylphosphonium derivative of the nitrogen mustard chlorambucil. We show that Mito-Chlor localizes to cancer cell mitochondria where it acts on mtDNA to arrest cell cycle and induce cell death, resulting in a 80-fold enhancement of cell kill in a panel of breast and pancreatic cancer cell lines that are insensitive to the parent drug. Significantly, Mito-Chlor delayed tumor progression in a mouse xenograft model of human pancreatic cancer. This is a first example of repurposing chlorambucil, a drug not used in breast and pancreatic cancer treatment, as a novel drug candidate for these diseases.
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Affiliation(s)
- Melissa Millard
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California , 1985 Zonal Avenue, Los Angeles, California 90089, United States
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105
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McFadden MJ, Lee WKY, Brennan JD, Junop MS. Delineation of key XRCC4/Ligase IV interfaces for targeted disruption of non-homologous end joining DNA repair. Proteins 2013; 82:187-94. [PMID: 23794378 DOI: 10.1002/prot.24349] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 06/04/2013] [Accepted: 06/10/2013] [Indexed: 01/04/2023]
Abstract
Efficient DNA repair mechanisms frequently limit the effectiveness of chemotherapeutic agents that act through DNA damaging mechanisms. Consequently, proteins involved in DNA repair have increasingly become attractive targets of high-throughput screening initiatives to identify modulators of these pathways. Disruption of the XRCC4-Ligase IV interaction provides a novel means to efficiently halt repair of mammalian DNA double strand break repair; however; the extreme affinity of these proteins presents a major obstacle for drug discovery. A better understanding of the interaction surfaces is needed to provide a more specific target for inhibitor studies. To clearly define key interface(s) of Ligase IV necessary for interaction with XRCC4, we developed a competitive displacement assay using ESI-MS/MS and determined the minimal inhibitory fragment of the XRCC4-interacting region (XIR) capable of disrupting a complex of XRCC4/XIR. Disruption of a single helix (helix 2) within the helix-loop-helix clamp of Ligase IV was sufficient to displace XIR from a preformed complex. Dose-dependent response curves for the disruption of the complex by either helix 2 or helix-loop-helix fragments revealed that potency of inhibition was greater for the larger helix-loop-helix peptide. Our results suggest a susceptibility to inhibition at the interface of helix 2 and future studies would benefit from targeting this surface of Ligase IV to identify modulators that disrupt its interaction with XRCC4. Furthermore, helix 1 and loop regions of the helix-loop-helix clamp provide secondary target surfaces to identify adjuvant compounds that could be used in combination to more efficiently inhibit XRCC4/Ligase IV complex formation and DNA repair.
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Affiliation(s)
- Meghan J McFadden
- Chemical Biology Graduate Program, Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada, L8S 4M1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada, L8N 3Z5
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106
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Gourzones-Dmitriev C, Kassambara A, Sahota S, Rème T, Moreaux J, Bourquard P, Hose D, Pasero P, Constantinou A, Klein B. DNA repair pathways in human multiple myeloma: role in oncogenesis and potential targets for treatment. Cell Cycle 2013; 12:2760-73. [PMID: 23966156 DOI: 10.4161/cc.25951] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Every day, cells are faced with thousands of DNA lesions, which have to be repaired to preserve cell survival and function. DNA repair is more or less accurate and could result in genomic instability and cancer. We review here the current knowledge of the links between molecular features, treatment, and DNA repair in multiple myeloma (MM), a disease characterized by the accumulation of malignant plasma cells producing a monoclonal immunoglobulin. Genetic instability and abnormalities are two hallmarks of MM cells and aberrant DNA repair pathways are involved in disease onset, primary translocations in MM cells, and MM progression. Two major drugs currently used to treat MM, the alkylating agent Melphalan and the proteasome inhibitor Bortezomib act directly on DNA repair pathways, which are involved in response to treatment and resistance. A better knowledge of DNA repair pathways in MM could help to target them, thus improving disease treatment.
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Affiliation(s)
- Claire Gourzones-Dmitriev
- CHU Montpellier; Institute of Research in Biotherapy; Montpellier, France; INSERM; U1040; Montpellier, France
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107
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Personalized synthetic lethality induced by targeting RAD52 in leukemias identified by gene mutation and expression profile. Blood 2013; 122:1293-304. [PMID: 23836560 DOI: 10.1182/blood-2013-05-501072] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Homologous recombination repair (HRR) protects cells from the lethal effect of spontaneous and therapy-induced DNA double-stand breaks. HRR usually depends on BRCA1/2-RAD51, and RAD52-RAD51 serves as back-up. To target HRR in tumor cells, a phenomenon called "synthetic lethality" was applied, which relies on the addiction of cancer cells to a single DNA repair pathway, whereas normal cells operate 2 or more mechanisms. Using mutagenesis and a peptide aptamer approach, we pinpointed phenylalanine 79 in RAD52 DNA binding domain I (RAD52-phenylalanine 79 [F79]) as a valid target to induce synthetic lethality in BRCA1- and/or BRCA2-deficient leukemias and carcinomas without affecting normal cells and tissues. Targeting RAD52-F79 disrupts the RAD52-DNA interaction, resulting in the accumulation of toxic DNA double-stand breaks in malignant cells, but not in normal counterparts. In addition, abrogation of RAD52-DNA interaction enhanced the antileukemia effect of already-approved drugs. BRCA-deficient status predisposing to RAD52-dependent synthetic lethality could be predicted by genetic abnormalities such as oncogenes BCR-ABL1 and PML-RAR, mutations in BRCA1 and/or BRCA2 genes, and gene expression profiles identifying leukemias displaying low levels of BRCA1 and/or BRCA2. We believe this work may initiate a personalized therapeutic approach in numerous patients with tumors displaying encoded and functional BRCA deficiency.
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108
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Williamson EA, Hromas R. Repressing DNA repair to enhance chemotherapy: targeting MyD88 in colon cancer. J Natl Cancer Inst 2013; 105:926-7. [PMID: 23766531 DOI: 10.1093/jnci/djt148] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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109
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Bret C, Klein B, Moreaux J. Nucleotide excision DNA repair pathway as a therapeutic target in patients with high-risk diffuse large B cell lymphoma. Cell Cycle 2013; 12:1811-2. [PMID: 23708513 PMCID: PMC3735686 DOI: 10.4161/cc.25115] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Boyd KD, Pawlyn C, Morgan GJ, Davies FE. Understanding the molecular biology of myeloma and its therapeutic implications. Expert Rev Hematol 2013; 5:603-17. [PMID: 23216592 DOI: 10.1586/ehm.12.51] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Myeloma develops due to the accumulation of multiple pathological genetic events, many of which have been defined. Hyperdiploidy and reciprocal translocations centered on the immunoglobulin heavy chain variable region constitute primary genetic lesions. These primary lesions co-operate with secondary genetic events including chromosomal deletions and gains, gene mutations and epigenetic modifiers such as DNA methylation to produce the malignant phenotype of myeloma. Some of these events have been linked with distinct clinical outcome and can be used to define patient groups. This review explores the molecular biology of myeloma and identifies how genetic lesions can be used to define high- and low-risk patient groups, and also defines potential targets for therapy. The authors also explore how this information can be used to guide therapeutic decision-making and the design and interpretation of clinical trials, both now and in the future.
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Affiliation(s)
- Kevin D Boyd
- The Institute of Cancer Research, Brookes Lawley Building, 15 Cotswold Road, Sutton, Surrey, UK
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111
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Genomic editing of the HIV-1 coreceptor CCR5 in adult hematopoietic stem and progenitor cells using zinc finger nucleases. Mol Ther 2013; 21:1259-69. [PMID: 23587921 PMCID: PMC3677314 DOI: 10.1038/mt.2013.65] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The HIV-1 coreceptor CCR5 is a validated target for HIV/AIDS therapy. The apparent elimination of HIV-1 in a patient treated with an allogeneic stem cell transplant homozygous for a naturally occurring CCR5 deletion mutation (CCR5(Δ32/Δ32)) supports the concept that a single dose of HIV-resistant hematopoietic stem cells can provide disease protection. Given the low frequency of naturally occurring CCR5(Δ32/Δ32) donors, we reasoned that engineered autologous CD34(+) hematopoietic stem/progenitor cells (HSPCs) could be used for AIDS therapy. We evaluated disruption of CCR5 gene expression in HSPCs isolated from granulocyte colony-stimulating factor (CSF)-mobilized adult blood using a recombinant adenoviral vector encoding a CCR5-specific pair of zinc finger nucleases (CCR5-ZFN). Our results demonstrate that CCR5-ZFN RNA and protein expression from the adenoviral vector is enhanced by pretreatment of HSPC with protein kinase C (PKC) activators resulting in >25% CCR5 gene disruption and that activation of the mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathway is responsible for this activity. Importantly, using an optimized dose of PKC activator and adenoviral vector we could generate CCR5-modified HSPCs which engraft in a humanized mouse model (albeit at a reduced level) and support multilineage differentiation in vitro and in vivo. Together, these data establish the basis for improved approaches exploiting adenoviral vector delivery in the modification of HSPCs.
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112
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Abstract
Chromosomal translocations are common contributors to malignancy, yet little is known about the precise molecular mechanisms by which they are generated. Sequencing translocation junctions in acute leukemias revealed that the translocations were likely mediated by a DNA double-strand break repair pathway termed nonhomologous end-joining (NHEJ). There are major 2 types of NHEJ: (1) the classical pathway initiated by the Ku complex, and (2) the alternative pathway initiated by poly ADP-ribose polymerase 1 (PARP1). Recent reports suggest that classical NHEJ repair components repress translocations, whereas alternative NHEJ components were required for translocations. The rate-limiting step for initiation of alternative NHEJ is the displacement of the Ku complex by PARP1. Therefore, we asked whether PARP1 inhibition could prevent chromosomal translocations in 3 translocation reporter systems. We found that 2 PARP1 inhibitors or repression of PARP1 protein expression strongly repressed chromosomal translocations, implying that PARP1 is essential for this process. Finally, PARP1 inhibition also reduced both ionizing radiation-generated and VP16-generated translocations in 2 cell lines. These data define PARP1 as a critical mediator of chromosomal translocations and raise the possibility that oncogenic translocations occurring after high-dose chemotherapy or radiation could be prevented by treatment with a clinically available PARP1 inhibitor.
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113
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Davidson D, Wang Y, Aloyz R, Panasci L. The PARP inhibitor ABT-888 synergizes irinotecan treatment of colon cancer cell lines. Invest New Drugs 2013; 31:461-8. [PMID: 23054213 PMCID: PMC3857790 DOI: 10.1007/s10637-012-9886-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 09/26/2012] [Indexed: 12/18/2022]
Abstract
Poly [ADP-ribose] polymerase-1 (PARP-1) localizes rapidly to sites of DNA damage and has been associated with various repair mechanisms including base excision repair (BER) and homologous recombination/non-homologous end joining (HRR/NHEJ). PARP-1 acts by adding poly-ADP ribose side chains to target proteins (PARylation) altering molecular interactions and functions. Recently small molecule inhibitors of PARP-1 have been shown to have significant clinical potential and third generation PARP inhibitors are currently being investigated in clinical trials. These drugs alone or in combination with radio/chemotherapy have resulted in meaningful patient responses and an increase in survival in metastatic breast cancer cases bearing BRCA-deficient or triple negative tumors and BRCA-deficient ovarian cancer patients. ABT-888, a potent PARP-1 inhibitor, sensitizes many cancer cells in-vitro and in-vivo to temozolomide. As such, we hypothesized that colon cancers would be sensitized to the DNA damaging chemotherapeutic agents, oxaliplatin and irinotecan, by ABT-888. Using colon cancer cell lines significant synergy was observed between ABT-888 and irinotecan at concentrations of ABT-888 as low as 0.125 μM. The level of synergy observed correlated with the degree of PARP1 inhibition as measured biochemically in cell lysates. ABT-888 at concentrations of 0.5-4 μM resulted in synergy with oxaliplatin. Furthermore, 24 h post treatment combinations of ABT-888/irinotecan generally resulted in increased G2/M cell cycle arrest and increased levels of DNA damage, followed by increased levels of apoptosis 48 h post treatment. In conclusion this study suggests that ABT-888 may be a clinically effective adjuvant to current colon cancer therapies that include the use of irinotecan and/or oxaliplatin.
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Affiliation(s)
- David Davidson
- Montreal Centre for Experimental Therapeutics in Cancer-Segal Cancer Center-Lady Davis Institute-Jewish General Hospital, McGill University, 3755, Côte Sainte Catherine Road, Montréal, Québec H3T 1E2, Canada
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114
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Rytelewski M, Ferguson PJ, Maleki Vareki S, Figueredo R, Vincent M, Koropatnick J. Inhibition of BRCA2 and Thymidylate Synthase Creates Multidrug Sensitive Tumor Cells via the Induction of Combined "Complementary Lethality". MOLECULAR THERAPY-NUCLEIC ACIDS 2013; 2:e78. [PMID: 23481354 PMCID: PMC3615817 DOI: 10.1038/mtna.2013.7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A high mutation rate leading to tumor cell heterogeneity is a driver of malignancy in human cancers. Paradoxically, however, genomic instability can also render tumors vulnerable to therapeutic attack. Thus, targeting DNA repair may induce an intolerable level of DNA damage in tumor cells. BRCA2 mediates homologous recombination repair, and BRCA2 polymorphisms increase cancer risk. However, tumors with BRCA2 mutations respond better to chemotherapy and are associated with improved patient prognosis. Thymidylate synthase (TS) is also involved in DNA maintenance and generates cellular thymidylate. We determined that antisense downregulation of BRCA2 synergistically potentiated drugs with mechanisms of action related to BRCA2 function (cisplatin, melphalan), a phenomenon we named “complementary lethality.” TS knockdown induced complementary lethality to TS-targeting drugs (5-FUdR and pemetrexed) but not DNA cross-linking agents. Combined targeting of BRCA2 and TS induced complementary lethality to both DNA-damaging and TS-targeting agents, thus creating multidrug sensitive tumors. In addition, we demonstrated for the first time that simultaneous downregulation of both targets induced combined complementary lethality to multiple mechanistically different drugs in the same cell population. In this study, we propose and define the concept of “complementary lethality” and show that actively targeting BRCA2 and TS is of potential therapeutic benefit in multidrug treatment of human tumors. This work has contributed to the development of a BRCA2-targeting antisense oligdeoxynucleotide (ASO) “BR-1” which we will test in vivo in combination with our TS-targeting ASO “SARI 83” and attempt early clinical trials in the future.
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Affiliation(s)
- Mateusz Rytelewski
- 1] Department of Microbiology and Immunology, Western University, London, Ontario, Canada [2] Cancer Research Laboratory Program, Lawson Health Research Institute, London, Ontario, Canada
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115
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Zhang J. The role of BRCA1 in homologous recombination repair in response to replication stress: significance in tumorigenesis and cancer therapy. Cell Biosci 2013; 3:11. [PMID: 23388117 PMCID: PMC3599463 DOI: 10.1186/2045-3701-3-11] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 12/20/2012] [Indexed: 12/16/2022] Open
Abstract
Germ line mutations in breast cancer gene 1 (BRCA1) predispose women to breast and ovarian cancers. Although BRCA1 is involved in many important biological processes, the function of BRCA1 in homologous recombination (HR) mediated repair is considered one of the major mechanisms contributing to its tumor suppression activity, and the cause of hypersensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors when BRCA1 is defective. Mounting evidence suggests that the mechanism of repairing DNA double strand breaks (DSBs) by HR is different than the mechanism operating when DNA replication is blocked. Although BRCA1 has been recognized as a central component in HR, the precise role of BRCA1 in HR, particularly under replication stress, has remained largely unknown. Given the fact that DNA lesions caused by replication blockages are the primary substrates for HR in mitotic cells, functional analysis of BRCA1 in HR repair in the context of replication stress should benefit our understanding of the molecular mechanisms underlying tumorigenesis associated with BRCA1 deficiencies, as well as the development of therapeutic approaches for cancer patients carrying BRCA1 mutations or reduced BRCA1 expression. This review focuses on the current advances in this setting and also discusses the significance in tumorigenesis and cancer therapy.
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Affiliation(s)
- Junran Zhang
- Department of Radiation Oncology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, BRB 323, Cleveland, OH, 44106, USA.
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116
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Nickoloff JA. Improving cancer therapy by combining cell biological, physical, and molecular targeting strategies. Chin J Cancer Res 2013; 25:7-9. [PMID: 23372336 DOI: 10.3978/j.issn.1000-9604.2013.01.06] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 01/10/2013] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA
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117
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Franca-Botelho ADC, Ferreira MC, Franca JL, Franca EL, Honorio-Franca AC. Breastfeeding and its Relationship with Reduction of Breast Cancer: A Review. Asian Pac J Cancer Prev 2012. [DOI: 10.7314/apjcp.2012.13.11.5327] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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118
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Fokas E, Steinbach JP, Rödel C. Biology of brain metastases and novel targeted therapies: time to translate the research. Biochim Biophys Acta Rev Cancer 2012; 1835:61-75. [PMID: 23142311 DOI: 10.1016/j.bbcan.2012.10.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/26/2012] [Accepted: 10/30/2012] [Indexed: 01/23/2023]
Abstract
Brain metastases (BM) occur in 20% to 40% of patients with cancer and result in significant morbidity and poor survival. The main therapeutic options include surgery, whole brain radiotherapy, stereotactic radiosurgery and chemotherapy. Although significant progress has been made in diagnostic and therapeutic methods, the prognosis in these patients remains poor. Furthermore, the poor penetrability of chemotherapy agents through the blood brain barrier (BBB) continues to pose a challenge in the management of this disease. Preclinical evidence suggests that new targeted treatments can improve local tumor control but our clinical experience with these agents remains limited. In addition, several clinical studies with these novel agents have produced disappointing results. This review will examine the knowledge of targeted therapies in BM. The preclinical and clinical evidence of their use in BM induced by breast cancer, non-small cell lung cancer and melanoma will be presented. In addition, we will discuss the role of antiangiogenic and radiosensitising agents in the treatment of BM and the current strategies available to increase BBB permeability. A better understanding of the mechanism of action of these agents will help us to identify the best targets for testing in future clinical studies.
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Affiliation(s)
- Emmanouil Fokas
- Department of Radiation Therapy and Oncology, Johann Wolfgang Goethe University, Frankfurt, Germany.
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119
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Blank JL, Liu XJ, Cosmopoulos K, Bouck DC, Garcia K, Bernard H, Tayber O, Hather G, Liu R, Narayanan U, Milhollen MA, Lightcap ES. Novel DNA damage checkpoints mediating cell death induced by the NEDD8-activating enzyme inhibitor MLN4924. Cancer Res 2012; 73:225-34. [PMID: 23100467 DOI: 10.1158/0008-5472.can-12-1729] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
MLN4924 is an investigational small-molecule inhibitor of the NEDD8-activating enzyme (NAE) in phase I clinical trials. NAE inhibition prevents the ubiquitination and proteasomal degradation of substrates for cullin-RING ubiquitin E3 ligases that support cancer pathophysiology, but the genetic determinants conferring sensitivity to NAE inhibition are unknown. To address this gap in knowledge, we conducted a genome-wide siRNA screen to identify genes and pathways that affect the lethality of MLN4924 in melanoma cells. Of the 154 genes identified, approximately one-half interfered with components of the cell cycle, apoptotic machinery, ubiquitin system, and DNA damage response pathways. In particular, genes involved in DNA replication, p53, BRCA1/BRCA2, transcription-coupled repair, and base excision repair seemed to be important for MLN4924 lethality. In contrast, genes within the G(2)-M checkpoint affected sensitivity to MLN4924 in colon cancer cells. Cell-cycle analysis in melanoma cells by flow cytometry following RNAi-mediated silencing showed that MLN4924 prevented the transition of cells from S-G(2) phase after induction of rereplication stress. Our analysis suggested an important role for the p21-dependent intra-S-phase checkpoint and extensive rereplication, whereas the ATR-dependent intra-S-phase checkpoint seemed to play a less dominant role. Unexpectedly, induction of the p21-dependent intra-S-phase checkpoint seemed to be independent of both Cdt1 stabilization and ATR signaling. Collectively, these data enhance our understanding of the mechanisms by which inhibition of NEDD8-dependent ubiquitination causes cell death, informing clinical development of MLN4924.
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Affiliation(s)
- Jonathan L Blank
- Discovery and Medical Biostatistics, Millennium Pharmaceuticals, Inc., Cambridge, MA 02139, USA
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Zhang D, Wang HB, Brinkman KL, Han SX, Xu B. Strategies for targeting the DNA damage response for cancer therapeutics. CHINESE JOURNAL OF CANCER 2012; 31:359-63. [PMID: 22704491 PMCID: PMC3777509 DOI: 10.5732/cjc.012.10087] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The DNA damage response is critical for cells to maintain genome stability and survival. In this review, we discuss approaches to targeting critical elements of the DNA damage response for radiosensitization and chemosensitization. In addition, we also discuss strategies for targeting DNA damage response and DNA repair defects in cancer cells for synthetic lethality.
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Affiliation(s)
- Dan Zhang
- Department of Radiation Oncology, The First Affiliated Hospital of Xi'an Jiaotong University Medical School, Xi'an, Shaanxi 710061, P. R. China;
- Department of Radiation Oncology, The Methodist Hospital Research Institute, Houston, TX 77030, USA.
| | - Hai-Bo Wang
- Department of Radiation Oncology, The Methodist Hospital Research Institute, Houston, TX 77030, USA.
| | - Kathryn L. Brinkman
- Department of Radiation Oncology, The Methodist Hospital Research Institute, Houston, TX 77030, USA.
| | - Su-Xia Han
- Department of Radiation Oncology, The First Affiliated Hospital of Xi'an Jiaotong University Medical School, Xi'an, Shaanxi 710061, P. R. China;
| | - Bo Xu
- Department of Radiation Oncology, The Methodist Hospital Research Institute, Houston, TX 77030, USA.
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121
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Wang Z, Wang F, Tang T, Guo C. The role of PARP1 in the DNA damage response and its application in tumor therapy. Front Med 2012; 6:156-64. [PMID: 22660976 DOI: 10.1007/s11684-012-0197-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 03/14/2012] [Indexed: 11/28/2022]
Abstract
Single-strand break repair protein poly(ADP-ribose) polymerase 1 (PARP1) catalyzes the poly(ADP-ribosyl)ation of many key proteins in vivo and thus plays important roles in multiple DNA damage response pathways, rendering it a promising target in cancer therapy. The tumor-suppressor effects of PARP inhibitors have attracted significant interest for development of novel cancer therapies. However, recent evidence indicated that the underlying mechanism of PARP inhibitors in tumor therapy is more complex than previously expected. The present review will focus on recent progress on the role of PARP1 in the DNA damage response and PARP inhibitors in cancer therapy. The emerging resistance of BRCA-deficient tumors to PARP inhibitors is also briefly discussed from the perspective of DNA damage and repair. These recent research advances will inform the selection of patient populations who can benefit from the PARP inhibitor treatment and development of effective drug combination strategies.
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Affiliation(s)
- Zhifeng Wang
- Laboratory of Disease Genomics and Individual Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100029, China
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122
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Hsu FM, Zhang S, Chen BPC. Role of DNA-dependent protein kinase catalytic subunit in cancer development and treatment. Transl Cancer Res 2012; 1:22-34. [PMID: 22943041 DOI: 10.3978/j.issn.2218-676x.2012.04.01] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a key component of the non-homologous end-joining (NHEJ) pathway, is involved in DNA double-strand break repair, immunocompetence, genomic integrity, and epidermal growth factor receptor signaling. Clinical studies indicate that expression and activity of DNA-PKcs is correlated with cancer progression and response to treatment. Various anti-DNA-PKcs strategies have been developed and tested in preclinical studies to exploit the benefit of DNA-PKcs inhibition in sensitization of radiotherapy and in combined modality therapy with other antitumor agents. In this article, we review the association between DNA-PKcs and cancer development and discuss current approaches and mechanisms for inhibition of DNA-PKcs. The future challenges are to understand how DNA-PKcs activity is correlated with cancer susceptibility and to identify those patients who would most benefit from DNA-PKcs inhibition.
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Affiliation(s)
- Feng-Ming Hsu
- Department of Oncology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
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123
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de Miranda NF, Björkman A, Pan-Hammarström Q. DNA repair: the link between primary immunodeficiency and cancer. Ann N Y Acad Sci 2012; 1246:50-63. [PMID: 22236430 DOI: 10.1111/j.1749-6632.2011.06322.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The adaptive component of the immune system depends greatly on the generation of genetic diversity provided by lymphocyte-specific genomic rearrangements. V(D)J recombination, class switch recombination (CSR), and somatic hypermutation (SHM) constitute complex and vulnerable processes that are orchestrated by a multitude of DNA repair pathways. When inherited defects in certain DNA repair proteins are present, lymphocyte development can be compromised and, consequently, patients can develop primary immunodeficiencies (PIDs). PID patients often have a strong predisposition for cancer development as a result of genomic instability generated from defective DNA repair mechanisms. Tumors of lymphoid origin are one of the most common PID-associated cancers, likely due to DNA lesions resulting from defective V(D)J, CSR, and SHM. In this review, we describe PID syndromes that confer an increased risk for cancer development. Furthermore, we discuss the role of the affected proteins in tumorigenesis/lymphomagenesis.
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Affiliation(s)
- Noel Fcc de Miranda
- Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
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124
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Zhang LQ, Cheranova D, Gibson M, Ding S, Heruth DP, Fang D, Ye SQ. RNA-seq reveals novel transcriptome of genes and their isoforms in human pulmonary microvascular endothelial cells treated with thrombin. PLoS One 2012; 7:e31229. [PMID: 22359579 PMCID: PMC3281071 DOI: 10.1371/journal.pone.0031229] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 01/04/2012] [Indexed: 11/23/2022] Open
Abstract
The dysregulation of vascular endothelial cells by thrombin has been implicated in the development of a number of pathologic disorders such as inflammatory conditions, cancer, diabetes, coronary heart disease. However, transcriptional regulation of vascular endothelial cells by thrombin is not completely understood. In the present study, Illumina RNA-seq was used to profile the transcriptome in human pulmonary microvascular endothelial cells (HMVEC-L) treated with thrombin for 6 h to gain insight into thrombin's direct effects on the endothelial function. Out of 100 million total reads from a paired end sequencing assay, 91–94% of the reads were aligned to over 16,000 genes in the reference human genome. Thrombin upregulated 150 known genes and 480 known isoforms, and downregulated 2,190 known genes and 3,574 known isoforms by at least 2 fold. Of note, thrombin upregulated 1,775 previously unknown isoforms and downregulated 12,202 previously unknown isoforms by at least 2 fold. Many genes displayed isoform specific differential expression levels and different usage of transcriptional start sites after the thrombin treatment. The cross comparisons between our RNA-seq data and those of DNA microarray analysis of either 6 h thrombin treated HUVEC or 5 h TNFα treated HMVEC have provided a significant overlapping list of differentially expressed genes, supporting the robust utility of our dataset. Further in-depth follow-up analysis of the transcriptional regulation reported in this study may shed light on molecular pathogenic mechanisms underlying thrombin mediated endothelial dysfunction in various diseases and provide new leads of potential therapeutic targets.
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Affiliation(s)
- Li Qin Zhang
- Department of Pediatrics, Children's Mercy Hospitals and Clinics, University of Missouri School of Medicine, Kansas City, Missouri, United States of America
| | - Dilyara Cheranova
- Department of Pediatrics, Children's Mercy Hospitals and Clinics, University of Missouri School of Medicine, Kansas City, Missouri, United States of America
| | - Margaret Gibson
- Department of Pediatrics, Children's Mercy Hospitals and Clinics, University of Missouri School of Medicine, Kansas City, Missouri, United States of America
| | - Shinghua Ding
- Dalton Cardiovascular Research Center and Department of Biological Engineering, University of Missouri, Columbia, Missouri, United States of America
| | - Daniel P. Heruth
- Department of Pediatrics, Children's Mercy Hospitals and Clinics, University of Missouri School of Medicine, Kansas City, Missouri, United States of America
| | - Deyu Fang
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Shui Qing Ye
- Department of Pediatrics, Children's Mercy Hospitals and Clinics, University of Missouri School of Medicine, Kansas City, Missouri, United States of America
- Department of Biomedical and Health Informatics, Children's Mercy Hospitals and Clinics, University of Missouri School of Medicine, Kansas City, Missouri, United States of America
- * E-mail:
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125
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Postel-Vinay S, Vanhecke E, Olaussen KA, Lord CJ, Ashworth A, Soria JC. The potential of exploiting DNA-repair defects for optimizing lung cancer treatment. Nat Rev Clin Oncol 2012; 9:144-55. [PMID: 22330686 DOI: 10.1038/nrclinonc.2012.3] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The tumor genome is commonly aberrant as a consequence of mutagenic insult and incomplete DNA repair. DNA repair as a therapeutic target has recently received considerable attention owing to the promise of drugs that target tumor-specific DNA-repair enzymes and potentiate conventional cytotoxic therapy through mechanism-based approaches, such as synthetic lethality. Treatment for non-small-cell lung cancer (NSCLC) consists mainly of platinum-based chemotherapy regimens and improvements are urgently needed. Optimizing treatment according to tumor status for DNA-repair biomarkers, such as ERCC1, BRCA1 or RRM1, could predict response to platinum, taxanes and gemcitabine-based therapies, respectively, and might improve substantially the response of individual patients' tumors. Finally, recent data on germline variation in DNA-repair genes may also be informative. Here, we discuss how a molecular and functional DNA-repair classification of NSCLC may aid clinical decision making and improve patient outcome.
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Affiliation(s)
- Sophie Postel-Vinay
- INSERM U981, Department of Medicine, Université Paris-Sud XI-Institut Gustave Roussy, 114 rue Edouard Vaillant, 94805 Villejuif, France
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126
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Bulgar AD, Weeks LD, Miao Y, Yang S, Xu Y, Guo C, Markowitz S, Oleinick N, Gerson SL, Liu L. Removal of uracil by uracil DNA glycosylase limits pemetrexed cytotoxicity: overriding the limit with methoxyamine to inhibit base excision repair. Cell Death Dis 2012; 3:e252. [PMID: 22237209 PMCID: PMC3270269 DOI: 10.1038/cddis.2011.135] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 11/09/2011] [Accepted: 11/09/2011] [Indexed: 01/03/2023]
Abstract
Uracil DNA glycosylase (UDG) specifically removes uracil bases from DNA, and its repair activity determines the sensitivity of the cell to anticancer agents that are capable of introducing uracil into DNA. In the present study, the participation of UDG in the response to pemetrexed-induced incorporation of uracil into DNA was studied using isogenic human tumor cell lines with or without UDG (UDG(+/+)/UDG(-/-)). UDG(-/-) cells were very sensitive to pemetrexed. Cell killing by pemetrexed was associated with genomic uracil accumulation, stalled DNA replication, and catastrophic DNA strand breaks. By contrast, UDG(+/+) cells were >10 times more resistant to pemetrexed due to the rapid removal of uracil from DNA by UDG and subsequent repair of the resultant AP sites (abasic sites) via the base excision repair (BER). The resistance to pemetrexed in UDG(+/+) cells could be reversed by the addition of methoxyamine (MX), which binds to AP sites and interrupts BER pathway. Furthermore, MX-bound AP sites induced cell death was related to their cytotoxic effect of dual inactivation of UDG and topoisomerase IIα, two genes that are highly expressed in lung cancer cells in comparison with normal cells. Thus, targeting BER-based therapy exhibits more selective cytotoxicity on cancer cells through a synthetic lethal mechanism.
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Affiliation(s)
- A D Bulgar
- Department of Medicine, Division of Hematology/Oncology, Case Western Reserve University, Cleveland, OH, USA
| | - L D Weeks
- Department of Medicine, Division of Hematology/Oncology, Case Western Reserve University, Cleveland, OH, USA
| | - Y Miao
- Department of Medicine, Division of Hematology/Oncology, Case Western Reserve University, Cleveland, OH, USA
| | - S Yang
- Case Comprehensive Cancer Center, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
| | - Y Xu
- Case Comprehensive Cancer Center, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
- Department of Chemistry, Cleveland State University, Cleveland, OH, USA
| | - C Guo
- Department of Medicine, Division of Hematology/Oncology, Case Western Reserve University, Cleveland, OH, USA
| | - S Markowitz
- Department of Medicine, Division of Hematology/Oncology, Case Western Reserve University, Cleveland, OH, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
- Department of Chemistry, Cleveland State University, Cleveland, OH, USA
- Department of Genetics, Case Western Reserve University, Cleveland, OH, USA
| | - N Oleinick
- Case Comprehensive Cancer Center, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
- Department of Radiation Oncology, Case Western Reserve University, Cleveland, OH, USA
| | - S L Gerson
- Department of Medicine, Division of Hematology/Oncology, Case Western Reserve University, Cleveland, OH, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
| | - L Liu
- Department of Medicine, Division of Hematology/Oncology, Case Western Reserve University, Cleveland, OH, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, USA
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127
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Kotsinas A, Aggarwal V, Tan EJ, Levy B, Gorgoulis VG. PIG3: a novel link between oxidative stress and DNA damage response in cancer. Cancer Lett 2011; 327:97-102. [PMID: 22178897 DOI: 10.1016/j.canlet.2011.12.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 12/05/2011] [Accepted: 12/06/2011] [Indexed: 11/25/2022]
Abstract
Reactive oxygen species (ROS), the most prominent free radicals produced in cells, can have both beneficial and detrimental effects on them. Many genes are known to be involved in ROS regulation. P53 inducible gene 3 (PIG3 or TP53I3) was identified in an analysis of genes induced by p53 before the onset of apoptosis. It is a widely conserved gene between many species. Until now it has been shown to exert two disparate cellular roles. The first is that of ROS producer linked to p53 induced apoptosis. In this context, it exhibits a NADPH dependent reductase activity with orthoquinones. The second is that of a component of the DNA damage response pathway. While it is considered as a p53 dependent pro-apoptotic gene, it is rarely affected in cancer. This data does not support an anti-tumor activity. In the present review we present and discuss aspects on the regulation and function of this factor and how it is implicated in cancer. We conclude by proposing that PIG3 may possibly have a role in cancer cell survival.
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Affiliation(s)
- Athanassios Kotsinas
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, University of Athens, Greece
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128
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Nilsen L, Forstrøm RJ, Bjørås M, Alseth I. AP endonuclease independent repair of abasic sites in Schizosaccharomyces pombe. Nucleic Acids Res 2011; 40:2000-9. [PMID: 22084197 PMCID: PMC3300018 DOI: 10.1093/nar/gkr933] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Abasic (AP) sites are formed spontaneously and are inevitably intermediates during base excision repair of DNA base damages. AP sites are both mutagenic and cytotoxic and key enzymes for their removal are AP endonucleases. However, AP endonuclease independent repair initiated by DNA glycosylases performing β,δ-elimination cleavage of the AP sites has been described in mammalian cells. Here, we describe another AP endonuclease independent repair pathway for removal of AP sites in Schizosaccharomyces pombe that is initiated by a bifunctional DNA glycosylase, Nth1 and followed by cleavage of the baseless sugar residue by tyrosyl phosphodiesterase Tdp1. We propose that repair is completed by the action of a polynucleotide kinase, a DNA polymerase and finally a DNA ligase to seal the gap. A fission yeast double mutant of the major AP endonuclease Apn2 and Tdp1 shows synergistic increase in MMS sensitivity, substantiating that Apn2 and Tdp1 process the same substrate. These results add new knowledge to the complex cellular response to AP sites, which could be exploited in chemotherapy where synthetic lethality is a key strategy of treatment.
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Affiliation(s)
- Line Nilsen
- Department of Microbiology, Oslo University Hospital HF Rikshospitalet, PO Box 4950 Nydalen, N-0424 Oslo, Norway
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129
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Kasparek TR, Humphrey TC. DNA double-strand break repair pathways, chromosomal rearrangements and cancer. Semin Cell Dev Biol 2011; 22:886-97. [PMID: 22027614 DOI: 10.1016/j.semcdb.2011.10.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 10/07/2011] [Accepted: 10/12/2011] [Indexed: 01/12/2023]
Abstract
Chromosomal rearrangements, which can lead to oncogene activation and tumour suppressor loss, are a hallmark of cancer cells. Such outcomes can result from both the repair and misrepair of DNA ends, which arise from a variety of lesions including DNA double strand breaks (DSBs), collapsed replication forks and dysfunctional telomeres. Here we review the mechanisms by which non-homologous end joining (NHEJ) and homologous recombination (HR) repair pathways can both promote chromosomal rearrangements and also suppress them in response to such lesions, in accordance with their increasingly recognised tumour suppressor function. Further, we consider how chromosomal rearrangements, together with a modular approach towards understanding their etiology, may be exploited for cancer therapy.
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Affiliation(s)
- Torben R Kasparek
- CRUK/MRC Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Oxford, UK
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130
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Bialonska D, Song K, Bolton PH. Complexes of mismatched and complementary DNA with minor groove binders. Structures at nucleotide resolution via an improved hydroxyl radical cleavage methodology. Mutat Res 2011; 726:47-53. [PMID: 21893212 DOI: 10.1016/j.mrgentox.2011.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 08/20/2011] [Accepted: 08/23/2011] [Indexed: 11/18/2022]
Abstract
Tumor cell lines can replicate faster than normal cells and many also have defective DNA repair pathways. This has lead to the investigation of the inhibition of DNA repair proteins as a means of therapeutic intervention. An alternative approach is to hide or mask damaged DNA from the repair systems. We have developed a protocol to investigate the structures of the complexes of damaged DNA with drug like molecules. Nucleotide resolution structural information can be obtained using an improved hydroxyl radical cleavage protocol. The use of a dT(n) tail increases the length of the smallest fragments of interest and allows efficient co-precipitation of the fragments with poly(A). The use of a fluorescent label, on the 5' end of the dT(n) tail, in conjunction with modified cleavage reaction conditions, avoids the lifetime and other problems with (32)P labeling. The structures of duplex DNAs containing AC and CC mismatches in the presence and absence of minor groove binders have been investigated as have those of the fully complementary DNA. The results indicate that the structural perturbations of the mismatches are localized, are sequence dependent and that the presence of a mismatch can alter the binding of drug like molecules.
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