1
|
Wang W, Rodriguez-Silva M, Acanda de la Rocha AM, Wolf AL, Lai Y, Liu Y, Reinhold WC, Pommier Y, Chambers JW, Tse-Dinh YC. Tyrosyl-DNA Phosphodiesterase 1 and Topoisomerase I Activities as Predictive Indicators for Glioblastoma Susceptibility to Genotoxic Agents. Cancers (Basel) 2019; 11:cancers11101416. [PMID: 31547492 PMCID: PMC6827102 DOI: 10.3390/cancers11101416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/06/2019] [Accepted: 09/19/2019] [Indexed: 02/06/2023] Open
Abstract
Glioblastoma (GBM) patients have an estimated survival of ~15 months with treatment, and the standard of care only modestly enhances patient survival. Identifying biomarkers representing vulnerabilities may allow for the selection of efficacious chemotherapy options to address personalized variations in GBM tumors. Irinotecan targets topoisomerase I (TOP1) by forming a ternary DNA-TOP1 cleavage complex (TOP1cc), inducing apoptosis. Tyrosyl-DNA phosphodiesterase 1 (TDP1) is a crucial repair enzyme that may reduce the effectiveness of irinotecan. We treated GBM cell lines with increasing concentrations of irinotecan and compared the IC50 values. We found that the TDP1/TOP1 activity ratio had the strongest correlation (Pearson correlation coefficient R = 0.972, based on the average from three sets of experiments) with IC50 values following irinotecan treatment. Increasing the TDP1/TOP1 activity ratio by the ectopic expression of wild-type TDP1 increased in irinotecan IC50, while the expression of the TDP1 catalytic-null mutant did not alter the susceptibility to irinotecan. The TDP1/TOP1 activity ratio may be a new predictive indicator for GBM vulnerability to irinotecan, allowing for the selection of individual patients for irinotecan treatment based on risk-benefit. Moreover, TDP1 inhibitors may be a novel combination treatment with irinotecan to improve GBM patient responsiveness to genotoxic chemotherapies.
Collapse
Affiliation(s)
- Wenjie Wang
- Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA.
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - Monica Rodriguez-Silva
- Department of Environmental Health Sciences, Florida International University, Miami, FL 33199, USA.
| | | | - Aizik L Wolf
- Department of Neurosurgery, Miami Neuroscience Center at Larkin, South Miami, FL 33143, USA.
| | - Yanhao Lai
- Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA.
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - Yuan Liu
- Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA.
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - William C Reinhold
- Developmental Therapeutic Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA.
| | - Yves Pommier
- Developmental Therapeutic Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA.
| | - Jeremy W Chambers
- Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA.
- Department of Environmental Health Sciences, Florida International University, Miami, FL 33199, USA.
| | - Yuk-Ching Tse-Dinh
- Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA.
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| |
Collapse
|
2
|
Daudee R, Gonen R, German U, Orion I, Alfassi ZB, Priel E. DNA Topoisomerase IB as a Potential Ionizing Radiation Exposure and Dose Biomarker. Radiat Res 2018; 189:652-660. [PMID: 29633912 DOI: 10.1667/rr14859.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In radiation exposure scenarios where physical dosimetry is absent or inefficient, dose estimation must rely on biological markers. A reliable biomarker is of utmost importance in correlating biological system changes with radiation exposure. Human DNA topoisomerase ІB (topo І) is a ubiquitous nuclear enzyme, which is involved in essential cellular processes, including transcription, DNA replication and DNA repair, and is the target of anti-cancer drugs. It has been shown that the cellular activity of this enzyme is significantly sensitive to various DNA lesions, including radiation-induced DNA damages. Therefore, we investigated the potential of topo I as a biomarker of radiation exposure and dose. We examined the effect of exposure of different human cells to beta, X-ray and gamma radiation on the cellular catalytic activity of topo I. The results demonstrate a significant reduction in the DNA relaxation activity of topo I after irradiation and the level of the reduction was correlated with radiation dose. In normal human peripheral blood lymphocytes, exposure for 3 h to an integral dose of 0.065 mGy from tritium reduced the enzyme activity to less than 25%. In MG-63 osteoblast-like cells and in human pulmonary fibroblast (HPF) cells exposed to gamma radiation from a 60Co source (up to 2 Gy) or to X rays (up to 2.8 Gy), a significant decrease in topo I catalytic activity was also observed. We observed that the enzyme-protein level was not altered but was partially posttranslational modified by ADP-ribosylation of the enzyme protein that is known to reduce topo I activity. The results of this study suggest that the decrease in the cellular topo I catalytic activity after low-dose exposure to different radiation types may be considered as a novel biomarker of ionizing radiation exposure and dose. For this purpose, a suitable ELISA-based method for large-scale analysis of radiation-induced topo I modification is under development.
Collapse
Affiliation(s)
- Rotem Daudee
- a The Shraga Segal Department of Immunology, Microbiology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,b Department of Nuclear Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel.,c Nuclear Research Center, Negev, Beer Sheva, Israel
| | - Rafi Gonen
- a The Shraga Segal Department of Immunology, Microbiology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,b Department of Nuclear Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel.,c Nuclear Research Center, Negev, Beer Sheva, Israel
| | - Uzi German
- c Nuclear Research Center, Negev, Beer Sheva, Israel
| | - Itzhak Orion
- b Department of Nuclear Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Zeev B Alfassi
- b Department of Nuclear Engineering, Faculty of Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Esther Priel
- a The Shraga Segal Department of Immunology, Microbiology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| |
Collapse
|
3
|
Zhang X, Jia D, Ao J, Liu H, Zang Y, Azam M, Habib SL, Li J, Ruan X, Jia H, Wang X, Li B. Identification of Bisindolylmaleimide IX as a potential agent to treat drug-resistant BCR-ABL positive leukemia. Oncotarget 2018; 7:69945-69960. [PMID: 27564101 PMCID: PMC5342526 DOI: 10.18632/oncotarget.11566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 08/08/2016] [Indexed: 11/25/2022] Open
Abstract
Chronic myeloid leukemia (CML) treatment with BCR-ABL inhibitors is often hampered by development of drug resistance. In a screen for novel chemotherapeutic drug candidates with genotoxic activity, we identified a bisindolylmaleimide derivative, IX, as a small molecule compound with therapeutic potential against CML including drug-resistant CML. We show that Bisindolylmaleimide IX inhibits DNA topoisomerase, generates DNA breaks, activates the Atm-p53 and Atm-Chk2 pathways, and induces cell cycle arrest and cell death. Interestingly, Bisindolylmaleimide IX is highly effective in targeting cells positive for BCR-ABL. BCR-ABL positive cells display enhanced DNA damage and increased cell cycle arrest in response to Bisindolylmaleimide IX due to decreased expression of topoisomerases. Cells positive for BCR-ABL or drug-resistant T315I BCR-ABL also display increased cytotoxicity since Bisindolylmaleimide IX inhibits B-Raf and the downstream oncogene addiction pathway. Mouse cancer model experiments showed that Bisindolylmaleimide IX, at doses that show little side effect, was effective in treating leukemia-like disorders induced by BCR-ABL or T315I BCR-ABL, and prolonged the lifespan of these model mice. Thus, Bisindolylmaleimide IX presents a novel drug candidate to treat drug-resistant CML via activating BCR-ABL-dependent genotoxic stress response and inhibiting the oncogene addiction pathway activated by BCR-ABL.
Collapse
Affiliation(s)
- Xin Zhang
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
| | - Deyong Jia
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
| | - Junping Ao
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Huijuan Liu
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
| | - Yi Zang
- National Center for Drug Screening, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Mohammad Azam
- Divisions of Pathology, Hematology and Cancer Biology, Cancer and Blood Disease Institute, Cincinnati Children's Hospital and Medical Center, Cincinnati, OH, USA
| | - Samy L Habib
- South Texas Veterans Health Care System and Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Jia Li
- National Center for Drug Screening, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xinsen Ruan
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
| | - Hao Jia
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
| | - Xueying Wang
- Department of Biochemistry, National University of Singapore, Singapore
| | - Baojie Li
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China.,Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| |
Collapse
|
4
|
Jandu H, Aluzaite K, Fogh L, Thrane SW, Noer JB, Proszek J, Do KN, Hansen SN, Damsgaard B, Nielsen SL, Stougaard M, Knudsen BR, Moreira J, Hamerlik P, Gajjar M, Smid M, Martens J, Foekens J, Pommier Y, Brünner N, Schrohl AS, Stenvang J. Molecular characterization of irinotecan (SN-38) resistant human breast cancer cell lines. BMC Cancer 2016; 16:34. [PMID: 26801902 PMCID: PMC4722663 DOI: 10.1186/s12885-016-2071-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 01/18/2016] [Indexed: 01/04/2023] Open
Abstract
Background Studies in taxane and/or anthracycline refractory metastatic breast cancer (mBC) patients have shown approximately 30 % response rates to irinotecan. Hence, a significant number of patients will experience irinotecan-induced side effects without obtaining any benefit. The aim of this study was to lay the groundwork for development of predictive biomarkers for irinotecan treatment in BC. Methods We established BC cell lines with acquired or de novo resistance to SN-38, by exposing the human BC cell lines MCF-7 and MDA-MB-231 to either stepwise increasing concentrations over 6 months or an initial high dose of SN-38 (the active metabolite of irinotecan), respectively. The resistant cell lines were analyzed for cross-resistance to other anti-cancer drugs, global gene expression, growth rates, TOP1 and TOP2A gene copy numbers and protein expression, and inhibition of the breast cancer resistance protein (ABCG2/BCRP) drug efflux pump. Results We found that the resistant cell lines showed 7–100 fold increased resistance to SN-38 but remained sensitive to docetaxel and the non-camptothecin Top1 inhibitor LMP400. The resistant cell lines were characterized by Top1 down-regulation, changed isoelectric points of Top1 and reduced growth rates. The gene and protein expression of ABCG2/BCRP was up-regulated in the resistant sub-lines and functional assays revealed BCRP as a key mediator of SN-38 resistance. Conclusions Based on our preclinical results, we suggest analyzing the predictive value of the BCRP in breast cancer patients scheduled for irinotecan treatment. Moreover, LMP400 should be tested in a clinical setting in breast cancer patients with resistance to irinotecan. Electronic supplementary material The online version of this article (doi:10.1186/s12885-016-2071-1) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Haatisha Jandu
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Kristina Aluzaite
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Louise Fogh
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Sebastian Wingaard Thrane
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Julie B Noer
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Joanna Proszek
- Department of Pathology, Aarhus University Hospital, Noerrebrogade 44, building 18B, 8000, Aarhus C, Denmark.
| | - Khoa Nguyen Do
- DTU Multiassay Core (DMAC), Technical University of Denmark, Kemitorvet Building 208, DK-2800, Lyngby, Denmark.
| | - Stine Ninel Hansen
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Britt Damsgaard
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Signe Lykke Nielsen
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Magnus Stougaard
- Department of Pathology, Aarhus University Hospital, Noerrebrogade 44, building 18B, 8000, Aarhus C, Denmark.
| | - Birgitta R Knudsen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, 8000, Aarhus C, Denmark.
| | - José Moreira
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Petra Hamerlik
- Brain Tumor Biology, Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Madhavsai Gajjar
- Brain Tumor Biology, Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Marcel Smid
- Erasmus MC Cancer Institute, Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC, Rotterdam, The Netherlands.
| | - John Martens
- Erasmus MC Cancer Institute, Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC, Rotterdam, The Netherlands.
| | - John Foekens
- Erasmus MC Cancer Institute, Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC, Rotterdam, The Netherlands.
| | - Yves Pommier
- National Institutes of Health, National Cancer Institute, Center for Cancer Research, Developmental Therapeutics Branch and Laboratory of Molecular, Pharmacology, 37 Convent Drive, Building 37, Room 5068, Bethesda, MD, 20892-4255, USA.
| | - Nils Brünner
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Anne-Sofie Schrohl
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| | - Jan Stenvang
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.
| |
Collapse
|
5
|
c-Abl tyrosine kinase promotes adipocyte differentiation by targeting PPAR-gamma 2. Proc Natl Acad Sci U S A 2014; 111:16365-70. [PMID: 25368164 DOI: 10.1073/pnas.1411086111] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Adipocyte differentiation, or adipogenesis, is a complex and highly regulated process. A recent proteomic analysis has predicted that the nonreceptor tyrosine kinase Abelson murine leukemia viral oncogene (c-Abl) is a putative key regulator of adipogenesis, but the underlying mechanism remained obscure. We found that c-Abl was activated during the early phase of mouse 3T3-L1 preadipocyte differentiation. Moreover, c-Abl activity was essential and its inhibition blocked differentiation to mature adipocytes. c-Abl directly controlled the expression and activity of the master adipogenic regulator peroxisome proliferator-activator receptor gamma 2 (PPARγ2). PPARγ2 physically associated with c-Abl and underwent phosphorylation on two tyrosine residues within its regulatory activation function 1 (AF1) domain. We demonstrated that this process positively regulates PPARγ2 stability and adipogenesis. Remarkably, c-Abl binding to PPARγ2 required the Pro12 residue that has a phenotypically well-studied common human genetic proline 12 alanine substitution (Pro12Ala) polymorphism. Our findings establish a critical role for c-Abl in adipocyte differentiation and explain the behavior of the known Pro12Ala polymorphism.
Collapse
|
6
|
Roy A, Tesauro C, Frøhlich R, Hede MS, Nielsen MJ, Kjeldsen E, Bonven B, Stougaard M, Gromova I, Knudsen BR. Decreased camptothecin sensitivity of the stem-cell-like fraction of Caco2 cells correlates with an altered phosphorylation pattern of topoisomerase I. PLoS One 2014; 9:e99628. [PMID: 24960044 PMCID: PMC4069021 DOI: 10.1371/journal.pone.0099628] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 05/17/2014] [Indexed: 12/27/2022] Open
Abstract
The CD44+ and CD44− subpopulations of the colorectal cancer cell line Caco2 were analyzed separately for their sensitivities to the antitumor drug camptothecin. CD44+ cells were less sensitive to camptothecin than CD44− cells. The relative resistance of CD44+ cells was correlated with (i) reduced activity of the nuclear enzyme topoisomerase I and (ii) insensitivity of this enzyme to camptothecin when analyzed in extracts. In contrast, topoisomerase I activity was higher in extracts from CD44− cells and the enzyme was camptothecin sensitive. Topoisomerase I from the two subpopulations were differentially phosphorylated in a manner that appeared to determine the drug sensitivity and activity of the enzyme. This finding was further supported by the fact that phosphorylation of topoisomerase I in CD44+ cell extract by protein kinase CK2 converted the enzyme to a camptothecin sensitive, more active form mimicking topoisomerase I in extracts from CD44− cells. Conversely, dephosphorylation of topoisomerase I in extracts from CD44− cells rendered the enzyme less active and camptothecin resistant. These findings add to our understanding of chemotherapy resistance in the Caco2 CD44+ cancer stem cell model.
Collapse
Affiliation(s)
- Amit Roy
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Cinzia Tesauro
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Rikke Frøhlich
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | | | - Maria J. Nielsen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Eigil Kjeldsen
- Hemodiagnostic Laboratory, Cancercytogenetic Section, Aarhus University Hospital, Aarhus, Denmark
| | - Bjarne Bonven
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Magnus Stougaard
- Department of Pathology, Aarhus University Hospital, Aarhus, Denmark
| | - Irina Gromova
- Genome Integrity Unit, Proteomics in Cancer, Danish Cancer Research Center, Danish Cancer Society, Copenhagen, Denmark
| | - Birgitta R. Knudsen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
- * E-mail:
| |
Collapse
|
7
|
Hicks S, Labinskyy N, Piteo B, Laurent D, Mathew JE, Gupte SA, Edwards JG. Type II diabetes increases mitochondrial DNA mutations in the left ventricle of the Goto-Kakizaki diabetic rat. Am J Physiol Heart Circ Physiol 2013; 304:H903-15. [PMID: 23376826 DOI: 10.1152/ajpheart.00567.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mitochondrial dysfunction has a significant role in the development of diabetic cardiomyopathy. Mitochondrial oxidant stress has been accepted as the singular cause of mitochondrial DNA (mtDNA) damage as an underlying cause of mitochondrial dysfunction. However, separate from a direct effect on mtDNA integrity, diabetic-induced increases in oxidant stress alter mitochondrial topoisomerase function to propagate mtDNA mutations as a contributor to mitochondrial dysfunction. Both glucose-challenged neonatal cardiomyocytes and the diabetic Goto-Kakizaki (GK) rat were studied. In both the GK left ventricle (LV) and in cardiomyocytes, chronically elevated glucose presentation induced a significant increase in mtDNA damage that was accompanied by decreased mitochondrial function. TTGE analysis revealed a number of base pair substitutions in the 3' end of COX3 from GK LV mtDNA that significantly altered the protein sequence. Mitochondrial topoisomerase DNA cleavage activity in isolated mitochondria was significantly increased in the GK LV compared with Wistar controls. Both hydroxycamptothecin, a topoisomerase type 1 inhibitor, and doxorubicin, a topoisomerase type 2 inhibitor, significantly exacerbated the DNA cleavage activity of isolated mitochondrial extracts indicating the presence of multiple functional topoisomerases in the mitochondria. Mitochondrial topoisomerase function was significantly altered in the presence of H2O2 suggesting that separate from a direct effect on mtDNA, oxidant stress mediated type II diabetes-induced alterations of mitochondrial topoisomerase function. These findings are significant in that the activation/inhibition state of the mitochondrial topoisomerases will have important consequences for mtDNA integrity and the well being of the diabetic myocardium.
Collapse
Affiliation(s)
- S Hicks
- Department of Physiology, New York Medical College, Valhalla, NY, USA
| | | | | | | | | | | | | |
Collapse
|
8
|
Levi I, Segev Y, Priel E. Type 1 diabetes affects topoisomerase I activity and GlcNAcylation in rat organs: Kidney, liver and pancreas. Glycobiology 2012; 22:704-13. [DOI: 10.1093/glycob/cws008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
9
|
Verma NK, Dempsey E, Freeley M, Botting CH, Long A, Kelleher D, Volkov Y. Analysis of dynamic tyrosine phosphoproteome in LFA-1 triggered migrating T-cells. J Cell Physiol 2011; 226:1489-98. [PMID: 20945386 DOI: 10.1002/jcp.22478] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The ordered, directional migration of T-lymphocytes is a key process during immune surveillance and response. This requires cell adhesion to the high endothelial venules or to the extracellular matrix by a series of surface receptor/ligand interactions involving adhesion molecules of the integrin family including lymphocyte function associated molecule-1 (LFA-1) and intercellular adhesion molecules (ICAMs). Reversible protein phosphorylation is emerging as a key player in the regulation of biological functions with tyrosine phosphorylation playing a crucial role in signal transduction. Thus, the study of this type of post-translational modification at the proteomic level has great biological significance. In this work, phospho-enriched cell lysates from LFA-1-triggered migrating human T-cells were subjected to immunoaffinity purification of tyrosine phosphorylated proteins, mass spectrometric, and bioinformatic analysis. In addition to the identification of several well-documented proteins, the analysis suggested involvement of a number of new and novel proteins in LFA-1 induced T-cell migration. This dataset expands the list of the signaling components of the LFA-1 induced phosphotyrosine protein complexes in migrating T-cells that will be extremely useful in the study of their specific roles within LFA-1 associated signaling pathways. Identification of proteins previously not reported in the context of LFA-1 stimulated signal transduction might provide new insights into understanding the LFA-1 signaling networks and aid in the search for new potential therapeutic targets.
Collapse
Affiliation(s)
- Navin K Verma
- Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Ireland.
| | | | | | | | | | | | | |
Collapse
|
10
|
Good DM, Zubarev RA. Drug Target Identification from Protein Dynamics using Quantitative Pathway Analysis. J Proteome Res 2011; 10:2679-83. [DOI: 10.1021/pr200090m] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- David M. Good
- Chemistry I, Department of Molecular Biochemistry and Biophysics, Karolinska Institutet, Scheeles väg 2, 171 77 Stockholm, Sweden
| | - Roman A. Zubarev
- Chemistry I, Department of Molecular Biochemistry and Biophysics, Karolinska Institutet, Scheeles väg 2, 171 77 Stockholm, Sweden
| |
Collapse
|
11
|
Bandyopadhyay K, Gjerset RA. Protein kinase CK2 is a central regulator of topoisomerase I hyperphosphorylation and camptothecin sensitivity in cancer cell lines. Biochemistry 2011; 50:704-14. [PMID: 21182307 DOI: 10.1021/bi101110e] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Topoisomerase I (topo I) is required to unwind DNA during synthesis and provides the unique target for camptothecin-derived chemotherapeutic agents, including Irinotecan and Topotecan. While these agents are highly effective anticancer agents, some tumors do not respond due to intrinsic or acquired resistance, a process that remains poorly understood. Because of treatment toxicity, there is interest in identifying cellular factors that regulate tumor sensitivity and might serve as predictive biomarkers of therapy sensitivity. Here we identify the serine kinase, protein kinase CK2, as a central regulator of topo I hyperphosphorylation and activity and cellular sensitivity to camptothecin. In nine cancer cell lines and three normal tissue-derived cell lines we observe a consistent correlation between CK2 levels and camptothecin responsiveness. Two other topo I-targeted serine kinases, protein kinase C and cyclin-dependent kinase 1, do not show this correlation. Camptothecin-sensitive cancer cell lines display high CK2 activity, hyperphosphorylation of topo I, elevated topo I activity, and elevated phosphorylation-dependent complex formation between topo I and p14ARF, a topo I activator. Camptothecin-resistant cancer cell lines and normal cell lines display lower CK2 activity, lower topo I phosphorylation, lower topo I activity, and undetectable topo I/p14ARF complex formation. Experimental inhibition or activation of CK2 demonstrates that CK2 is necessary and sufficient for regulating these topo I properties and altering cellular responses to camptothecin. The results establish a cause and effect relationship between CK2 activity and camptothecin sensitivity and suggest that CK2, topo I phosphorylation, or topo I/p14ARF complex formation could provide biomarkers of therapy-responsive tumors.
Collapse
Affiliation(s)
- Keya Bandyopadhyay
- Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, California 92121, United States
| | | |
Collapse
|
12
|
Zehorai E, Eitan E, Hershfinkel M, Sekler I, Priel E. Glutamate regulates the activity of topoisomerase I in mouse cerebellum. Mol Neurobiol 2008; 38:242-52. [PMID: 18982460 DOI: 10.1007/s12035-008-8044-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Accepted: 10/10/2008] [Indexed: 10/21/2022]
Abstract
Topoisomerase I (topo I) is a nuclear enzyme which participates in most DNA transactions. It was shown to be inhibited in depolarized neurons by poly adenosine diphosphate (ADP)-ribosylation of the enzyme protein. We demonstrated previously an age and sex dependent topo I activity and enzyme protein level in the various regions of mouse brain. A specific distribution pattern of topo I was observed and the inhibitory neurons exhibited the highest enzyme activity and protein level in both the nucleus and the cytoplasm. Here, we show that neurotransmitters (glutamate and gamma-aminobutyric acid (GABA)) regulate the activity of topo I in mouse cerebellum sections. Glutamate exhibited a significant time-dependent inhibition of topo I activity but no effect of the enzyme protein level. GABA in contrary only slightly and transiently inhibited topo I activity. The inhibitory effect of glutamate was mediated by Ca(+2) and by ADP-ribosylation of topo I protein and the glutamate ionotropic receptors were involved. Glutamate also diminished the inhibitory effect of topotecan on topo I. These results point to distinct and highly specific effects of the major neurotransmitters on topo I activity in the cerebellum suggesting that topo I possesses a specific role in the brain which differs from its known biological functions.
Collapse
Affiliation(s)
- Eldar Zehorai
- The Shraga Segal Department of Microbiology & Immunology, Ben-Gurion University Cancer Research Center, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel
| | | | | | | | | |
Collapse
|
13
|
Hackbarth JS, Galvez-Peralta M, Dai NT, Loegering DA, Peterson KL, Meng XW, Karnitz LM, Kaufmann SH. Mitotic phosphorylation stimulates DNA relaxation activity of human topoisomerase I. J Biol Chem 2008; 283:16711-22. [PMID: 18408216 PMCID: PMC2423254 DOI: 10.1074/jbc.m802246200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 03/20/2008] [Indexed: 11/06/2022] Open
Abstract
Human DNA topoisomerase I (topo I) is an essential mammalian enzyme that regulates DNA supercoiling during transcription and replication. In addition, topo I is specifically targeted by the anticancer compound camptothecin and its derivatives. Previous studies have indicated that topo I is a phosphoprotein and that phosphorylation stimulates its DNA relaxation activity. The locations of most topo I phosphorylation sites have not been identified, preventing a more detailed examination of this modification. To address this issue, mass spectrometry was used to identify four topo I residues that are phosphorylated in intact cells: Ser(10), Ser(21), Ser(112), and Ser(394). Immunoblotting using anti-phosphoepitope antibodies demonstrated that these sites are phosphorylated during mitosis. In vitro kinase assays demonstrated that Ser(10) can be phosphorylated by casein kinase II, Ser(21) can be phosphorylated by protein kinase Calpha, and Ser(112) and Ser(394) can be phosphorylated by Cdk1. When wild type topo I was pulled down from mitotic cells and dephosphorylated with alkaline phosphatase, topo I activity decreased 2-fold. Likewise, topo I polypeptide with all four phosphorylation sites mutated to alanine exhibited 2-fold lower DNA relaxation activity than wild type topo I after isolation from mitotic cells. Further mutational analysis demonstrated that Ser(21) phosphorylation was responsible for this change. Consistent with these results, wild type topo I (but not S21A topo I) exhibited increased sensitivity to camptothecin-induced trapping on DNA during mitosis. Collectively these results indicate that topo I is phosphorylated during mitosis at multiple sites, one of which enhances DNA relaxation activity in vitro and interaction with DNA in cells.
Collapse
Affiliation(s)
- Jennifer S. Hackbarth
- Department of Biochemistry and Molecular
Biology and Division of Oncology Research, Mayo
Clinic, Mayo Graduate School, Rochester, Minnesota 55905
| | - Marina Galvez-Peralta
- Department of Biochemistry and Molecular
Biology and Division of Oncology Research, Mayo
Clinic, Mayo Graduate School, Rochester, Minnesota 55905
| | - Nga T. Dai
- Department of Biochemistry and Molecular
Biology and Division of Oncology Research, Mayo
Clinic, Mayo Graduate School, Rochester, Minnesota 55905
| | - David A. Loegering
- Department of Biochemistry and Molecular
Biology and Division of Oncology Research, Mayo
Clinic, Mayo Graduate School, Rochester, Minnesota 55905
| | - Kevin L. Peterson
- Department of Biochemistry and Molecular
Biology and Division of Oncology Research, Mayo
Clinic, Mayo Graduate School, Rochester, Minnesota 55905
| | - Xue W. Meng
- Department of Biochemistry and Molecular
Biology and Division of Oncology Research, Mayo
Clinic, Mayo Graduate School, Rochester, Minnesota 55905
| | - Larry M. Karnitz
- Department of Biochemistry and Molecular
Biology and Division of Oncology Research, Mayo
Clinic, Mayo Graduate School, Rochester, Minnesota 55905
| | - Scott H. Kaufmann
- Department of Biochemistry and Molecular
Biology and Division of Oncology Research, Mayo
Clinic, Mayo Graduate School, Rochester, Minnesota 55905
| |
Collapse
|
14
|
Imam SZ, Indig FE, Cheng WH, Saxena SP, Stevnsner T, Kufe D, Bohr VA. Cockayne syndrome protein B interacts with and is phosphorylated by c-Abl tyrosine kinase. Nucleic Acids Res 2007; 35:4941-51. [PMID: 17626041 PMCID: PMC1976445 DOI: 10.1093/nar/gkm386] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The Cockayne Syndrome group B (CSB) protein plays important roles in transcription, transcription-coupled nucleotide excision repair and base excision DNA repair. c-Abl kinase also plays a role in DNA repair as a regulator/coordinator of the DNA damage response. This study presents evidence that the N-terminal region of CSB interacts with the SH3 domain of c-Abl in vitro and in vivo. In addition, c-Abl kinase phosphorylates CSB at Tyr932. The subcellular localization of CSB to the nucleus and nucleolus is altered after phosphorylation by c-Abl. c-Abl-dependent phosphorylation of CSB increased in cells treated with hydrogen peroxide and decreased in cells pre-treated with STI-571, a c-Abl-specific protein kinase inhibitor. Activation of the c-Abl kinase in response to oxidative damage is not observed in CSB null cells. These results suggest that c-Abl and CSB may regulate each other in a reciprocal manner in response to oxidative stress.
Collapse
Affiliation(s)
- Syed Z. Imam
- Laboratory of Molecular Gerontology, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Research Resource Branch, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Danish Center for Molecular Gerontology, MBI, University of Aarhus, Denmark and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Fred E. Indig
- Laboratory of Molecular Gerontology, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Research Resource Branch, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Danish Center for Molecular Gerontology, MBI, University of Aarhus, Denmark and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Wen-Hsing Cheng
- Laboratory of Molecular Gerontology, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Research Resource Branch, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Danish Center for Molecular Gerontology, MBI, University of Aarhus, Denmark and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Satya P. Saxena
- Laboratory of Molecular Gerontology, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Research Resource Branch, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Danish Center for Molecular Gerontology, MBI, University of Aarhus, Denmark and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Tinna Stevnsner
- Laboratory of Molecular Gerontology, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Research Resource Branch, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Danish Center for Molecular Gerontology, MBI, University of Aarhus, Denmark and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Donald Kufe
- Laboratory of Molecular Gerontology, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Research Resource Branch, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Danish Center for Molecular Gerontology, MBI, University of Aarhus, Denmark and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Vilhelm A. Bohr
- Laboratory of Molecular Gerontology, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Research Resource Branch, National Institutes on Aging, National Institutes of Health, Baltimore, MD 21224, USA, Danish Center for Molecular Gerontology, MBI, University of Aarhus, Denmark and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
- *To whom correspondence should be addressed.+1-410-558-8162+1-410-558-8157
| |
Collapse
|
15
|
Yin JK, Liang YM, He XL, Lu JG, Zhang L, Bao GQ, Ma QJ. Fusion protein containing SH3 domain of c-Abl induces hepatocarcinoma cells to apoptosis. Hepatol Res 2007; 37:454-63. [PMID: 17539817 DOI: 10.1111/j.1872-034x.2007.00068.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM Through a preliminary test on a novel protein containing an HIV1-TAT domain and a SH3 domain of oncoprotein P210(BCR-ABL) (we named it after PTD-BCR/ABL SH3), we found that this protein shows inhibition activity of hepatocarcinoma cell HepG-2. The purpose of the present study is to explore the biological behavior of PTD-BCR/ABL SH3 fusion protein in hepatocarcinoma cells in vitro and in vivo. METHODS HepG-2 cells were cocultured with the fusion protein for the indicated time and studied in vitro by immunocytochemistry staining to demonstrate the localization of the protein, light and electron microscope observation in morphology research, MTT assay to draw a growth curve and to analyze inhibition ratio, DNA ladder and TUNEL staining to study apoptosis. Nude mice bearing HepG-2 tumors were used to test the antitumor activity of the fusion protein. RESULTS PTD-BCR/ABL SH3 fusion protein successfully entered into HepG-2 cells and localized in the nucleus. The protein had shown high cytotoxity through inducing HepG-2 cells to apoptosis, and in vivo. The growth speed of tumors in the treatment group was distinctly slower than those in the control group, and the survival time of mice in the treatment group was longer than those in the control group. The growth of the tumors had been inhibited in the treatment group, while other tissues, such as heart, liver, lung and kidney displayed normal morphology. CONCLUSION PTD-BCR/ABL SH3 fusion protein displays significant inhibitory activity of inducing hepatocarcinoma HepG-2 cells to apoptosis in vitro. It also showed therapeutic effects in vivo.
Collapse
Affiliation(s)
- Ji Kai Yin
- Department of General Surgery, Tangdu Hospital of Fourth Miliatry Medical University, Xi'an City, China
| | | | | | | | | | | | | |
Collapse
|
16
|
Bharti A, Ma PC, Salgia R. Biomarker discovery in lung cancer--promises and challenges of clinical proteomics. MASS SPECTROMETRY REVIEWS 2007; 26:451-66. [PMID: 17407130 DOI: 10.1002/mas.20125] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Lung cancer is a devastating illness with an overall poor prognosis. To effectively address this disease, early detection and novel therapeutics are required. Early detection of lung cancer is challenging, in part because of the lack of adequate tumor biomarkers. The goal of this review is to summarize the knowledge of current biomarkers in lung cancer, with a focus on important serum biomarkers. The current knowledge on the known serum cytokines and tumor biomarkers of lung cancer will be presented. Emerging trends and new findings in the search for novel diagnostic and therapeutic tumor biomarkers using proteomics technologies and platforms are emphasized, including recent advances in mass spectrometry to facilitate tumor biomarker discovery program in lung cancer. It is our hope that validation of these new research platforms and technologies will result in improved early detection, prognostication, and finally the treatment of lung cancer with potential novel molecularly targeted therapeutics.
Collapse
Affiliation(s)
- Ajit Bharti
- Center for Molecular Stress Response Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | | | | |
Collapse
|
17
|
St-Amant C, Lussier S, Lehoux J, Laberge RM, Boissonneault G. Altered phosphorylation of topoisomerase I following overexpression in an ovarian cancer cell line. Biochem Cell Biol 2006; 84:55-66. [PMID: 16462890 DOI: 10.1139/o05-157] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is a growing interest regarding the use of camptothecins (CPTs) for the management of ovarian cancer. Since topoisomerase I has been established as a prime target of these drugs in other experimental models, it was important to determine whether sensitivity to CPTs in ovarian cancer cells is also correlated with the cellular level of this enzyme. Despite the 7-fold increase in topoisomerase expression achieved by adenovirus-mediated expression, the sensitivity to a CPT derivative (topotecan), was not improved compared with control cells harboring an endogenous level of the enzyme. This observation is in accordance with the similar level of topoisomerase I activity found in control and overexpressing cells and suggests that these cells may efficiently regulate the enzyme activity. Indeed, topoisomerase I overexpressing cells are characterized by a lack of alkaline phosphatase sensitivity and elimination of the hyperphosphorylated form of the protein. Taken together, these observations strongly suggest that an alteration in the phosphorylation state of topoisomerase I could limit its activity and prevent improvement of CPT response in ovarian cancer cells. In addition, a limited extent of topoisomerase I phosphorylating activity was found in nuclear extract of OVCAR-3 cells. Hence, providing enhancement in topoisomerase I expression may not result in improvement of CPT response in ovarian cancer cells because of an efficient control of the phosphorylation state of the enzyme.
Collapse
Affiliation(s)
- Christiane St-Amant
- Département de Biochimie, Faculté de Médecine, Université de Sherbrooke, QC, Canada
| | | | | | | | | |
Collapse
|
18
|
Pond CD, Marshall KM, Barrows LR. Identification of a small topoisomerase I-binding peptide that has synergistic antitumor activity with 9-aminocamptothecin. Mol Cancer Ther 2006; 5:739-45. [PMID: 16546989 DOI: 10.1158/1535-7163.mct-05-0377] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The topoisomerase I (top1)-targeted camptothecin class of anticancer drugs is important in the treatment of several types of cancers. This class of drug inhibits the top1 enzyme during its catalytic DNA relaxation cycle, stabilizing the transient covalent top1-DNA complex by simultaneous noncovalent interactions with DNA and top1. We examined top1 using phage display because of the significance of this known top1-directed drug action. Several peptides that bind top1 were discovered and these were examined for top1 affinity, top1 catalytic and cleavage complex effects, and cytotoxic effects in cultured cell lines and in an in vivo tumor model. Although several peptides exhibited nanomolar and low-micromolar affinity for top1, none had cytotoxic effects when administered alone. However, in combination with 9-aminocamptothecin, one 15-mer peptide (SAYAATVRGPLSSAS) had synergistic cytotoxic effects with 9-aminocamptothecin both in the cytotoxicity assay and in nude mouse xenograft human tumor models. This report details the investigation of this peptide.
Collapse
Affiliation(s)
- Christopher D Pond
- Department of Pharmacology and Toxicology, University of Utah, 30 South 2000 East Room 201, Salt Lake City, UT 84112, USA
| | | | | |
Collapse
|