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Dreier MR, Walia J, de la Serna IL. Targeting SWI/SNF Complexes in Cancer: Pharmacological Approaches and Implications. EPIGENOMES 2024; 8:7. [PMID: 38390898 PMCID: PMC10885108 DOI: 10.3390/epigenomes8010007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/28/2024] [Accepted: 01/31/2024] [Indexed: 02/24/2024] Open
Abstract
SWI/SNF enzymes are heterogeneous multi-subunit complexes that utilize the energy from ATP hydrolysis to remodel chromatin structure, facilitating transcription, DNA replication, and repair. In mammalian cells, distinct sub-complexes, including cBAF, ncBAF, and PBAF exhibit varying subunit compositions and have different genomic functions. Alterations in the SWI/SNF complex and sub-complex functions are a prominent feature in cancer, making them attractive targets for therapeutic intervention. Current strategies in cancer therapeutics involve the use of pharmacological agents designed to bind and disrupt the activity of SWI/SNF complexes or specific sub-complexes. Inhibitors targeting the catalytic subunits, SMARCA4/2, and small molecules binding SWI/SNF bromodomains are the primary approaches for suppressing SWI/SNF function. Proteolysis-targeting chimeras (PROTACs) were generated by the covalent linkage of the bromodomain or ATPase-binding ligand to an E3 ligase-binding moiety. This engineered connection promotes the degradation of specific SWI/SNF subunits, enhancing and extending the impact of this pharmacological intervention in some cases. Extensive preclinical studies have underscored the therapeutic potential of these drugs across diverse cancer types. Encouragingly, some of these agents have progressed from preclinical research to clinical trials, indicating a promising stride toward the development of effective cancer therapeutics targeting SWI/SNF complex and sub-complex functions.
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Affiliation(s)
- Megan R Dreier
- Department of Cell and Cancer Biology, University of Toledo College of Medicine and Life Sciences, 3000 Arlington Ave, Toledo 43614, OH, USA
| | - Jasmine Walia
- Department of Cell and Cancer Biology, University of Toledo College of Medicine and Life Sciences, 3000 Arlington Ave, Toledo 43614, OH, USA
| | - Ivana L de la Serna
- Department of Cell and Cancer Biology, University of Toledo College of Medicine and Life Sciences, 3000 Arlington Ave, Toledo 43614, OH, USA
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Rakesh R, Chanana UB, Hussain S, Sharma S, Goel K, Bisht D, Patne K, Swer PB, Hockensmith JW, Muthuswami R. Altering mammalian transcription networking with ADAADi: An inhibitor of ATP-dependent chromatin remodeling. PLoS One 2021; 16:e0251354. [PMID: 33999958 PMCID: PMC8128233 DOI: 10.1371/journal.pone.0251354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 04/23/2021] [Indexed: 11/30/2022] Open
Abstract
Active DNA-dependent ATPase A Domain inhibitor (ADAADi) is the only known inhibitor of ATP-dependent chromatin remodeling proteins that targets the ATPase domain of these proteins. The molecule is synthesized by aminoglycoside phosphotransferase enzyme in the presence of aminoglycosides. ADAADi interacts with ATP-dependent chromatin remodeling proteins through motif Ia present in the conserved helicase domain, and thus, can potentially inhibit all members of this family of proteins. We show that mammalian cells are sensitive to ADAADi but with variable responses in different cell lines. ADAADi can be generated from a wide variety of aminoglycosides; however, cells showed differential response to ADAADi generated from various aminoglycosides. Using HeLa and DU145 cells as model system we have explored the effect of ADAADi on cellular functions. We show that the transcriptional network of a cell type is altered when treated with sub-lethal concentration of ADAADi. Although ADAADi has no known effects on DNA chemical and structural integrity, expression of DNA-damage response genes was altered. The transcripts encoding for the pro-apoptotic proteins were found to be upregulated while the anti-apoptotic genes were found to be downregulated. This was accompanied by increased apoptosis leading us to hypothesize that the ADAADi treatment promotes apoptotic-type of cell death by upregulating the transcription of pro-apoptotic genes. ADAADi also inhibited migration of cells as well as their colony forming ability leading us to conclude that the compound has effective anti-tumor properties.
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Affiliation(s)
| | | | - Saddam Hussain
- Chromatin Remodeling Laboratory, School of Life Sciences, JNU, New Delhi, India
| | - Soni Sharma
- Chromatin Remodeling Laboratory, School of Life Sciences, JNU, New Delhi, India
| | - Kaveri Goel
- Chromatin Remodeling Laboratory, School of Life Sciences, JNU, New Delhi, India
| | - Deepa Bisht
- Chromatin Remodeling Laboratory, School of Life Sciences, JNU, New Delhi, India
| | - Ketki Patne
- Chromatin Remodeling Laboratory, School of Life Sciences, JNU, New Delhi, India
| | - Pynskhem Bok Swer
- Chromatin Remodeling Laboratory, School of Life Sciences, JNU, New Delhi, India
| | - Joel W Hockensmith
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, United States of America
| | - Rohini Muthuswami
- Chromatin Remodeling Laboratory, School of Life Sciences, JNU, New Delhi, India
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Hartley A, Leung HY, Ahmad I. Targeting the BAF complex in advanced prostate cancer. Expert Opin Drug Discov 2021; 16:173-181. [PMID: 32936685 DOI: 10.1080/17460441.2020.1821644] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 09/07/2020] [Indexed: 12/26/2022]
Abstract
INTRODUCTION The BRG1/BRM associated factors (BAF) complex is a chromatin remodeling SWI/SNF which is mutated in 20% of cancers. This complex has many interchangeable subunits which may have oncogenic or tumor suppressor activity in a context-dependent manner. The BAF complex is mutated in 35-50% of metastatic prostate cancer (PC); however, its role in advanced disease is unclear. This review attempts to consolidate current knowledge of the BAF complex in PC and explore potential therapeutic approaches. AREAS COVERED This review covers the known roles of some BAF subunits, their alterations, and the models which best explain their mechanisms in driving PC. Following this, the authors provide their expert perspective on how this complex could be targeted in the future with a personalized medicine approach. EXPERT OPINION Personalized medicine would allow for patient stratification to exploit synthetic lethal strategies in targeting a mutated BAF complex as shown experimentally in other cancers. BAF dependency can also be targeted in patients stratified for other molecular markers such as BRG1 targeting in phosphatase and tensin homolog (PTEN) deficient PC.
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Affiliation(s)
- Andrew Hartley
- Urology Research Group, CRUK Beatson Institute , Glasgow, UK
| | - Hing Y Leung
- Urology Research Group, CRUK Beatson Institute , Glasgow, UK
- Institue of Cancer Sciences, University of Glasgow , Glasgow, UK
| | - Imran Ahmad
- Urology Research Group, CRUK Beatson Institute , Glasgow, UK
- Institue of Cancer Sciences, University of Glasgow , Glasgow, UK
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4
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The mechanisms of action of chromatin remodelers and implications in development and disease. Biochem Pharmacol 2020; 180:114200. [DOI: 10.1016/j.bcp.2020.114200] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/09/2020] [Accepted: 08/12/2020] [Indexed: 02/06/2023]
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5
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The Role of BRG1 in Antioxidant and Redox Signaling. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:6095673. [PMID: 33014273 PMCID: PMC7512085 DOI: 10.1155/2020/6095673] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 08/13/2020] [Accepted: 09/01/2020] [Indexed: 12/15/2022]
Abstract
Redox homeostasis is regulated by critical molecules that modulate antioxidant and redox signaling (ARS) within the cell. Imbalances among these molecules can lead to oxidative stress and damage to cell functions, causing a variety of diseases. Brahma-related gene 1 (BRG1), also known as SMARCA4, is the central ATPase catalytic subunit of the switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex, which plays a core role in DNA replication, repair, recombination, and transcriptional regulation. Numerous recent studies show that BRG1 is involved in the regulation of various cellular processes associated with ARS. BRG1, as a major factor in chromatin remodeling, is essential for the repair of oxidative stress-induced DNA damage and the activation of antioxidant genes under oxidative stress. Consequently, a comprehensive understanding of the roles of BRG1 in redox homeostasis is crucial to understand the normal functioning as well as pathological mechanisms. In this review, we summarized and discussed the role of BRG1 in the regulation of ARS.
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Bansal R, Hussain S, Chanana UB, Bisht D, Goel I, Muthuswami R. SMARCAL1, the annealing helicase and the transcriptional co-regulator. IUBMB Life 2020; 72:2080-2096. [PMID: 32754981 DOI: 10.1002/iub.2354] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/26/2020] [Accepted: 07/07/2020] [Indexed: 12/15/2022]
Abstract
The ATP-dependent chromatin remodeling proteins play an important role in DNA repair. The energy released by ATP hydrolysis is used for myriad functions ranging from nucleosome repositioning and nucleosome eviction to histone variant exchange. In addition, the distant member of the family, SMARCAL1, uses the energy to reanneal stalled replication forks in response to DNA damage. Biophysical studies have shown that this protein has the unique ability to recognize and bind specifically to DNA structures possessing double-strand to single-strand transition regions. Mutations in SMARCAL1 have been linked to Schimke immuno-osseous dysplasia, an autosomal recessive disorder that exhibits variable penetrance and expressivity. It has long been hypothesized that the variable expressivity and pleiotropic phenotypes observed in the patients might be due to the ability of SMARCAL1 to co-regulate the expression of a subset of genes within the genome. Recently, the role of SMARCAL1 in regulating transcription has been delineated. In this review, we discuss the biophysical and functional properties of the protein that help it to transcriptionally co-regulate DNA damage response as well as to bind to the stalled replication fork and stabilize it, thus ensuring genomic stability. We also discuss the role of SMARCAL1 in cancer and the possibility of using this protein as a chemotherapeutic target.
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Affiliation(s)
- Ritu Bansal
- Chromatin Remodeling Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Saddam Hussain
- Chromatin Remodeling Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Upasana Bedi Chanana
- Chromatin Remodeling Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Deepa Bisht
- Chromatin Remodeling Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Isha Goel
- Chromatin Remodeling Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Rohini Muthuswami
- Chromatin Remodeling Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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Chory EJ, Kirkland JG, Chang CY, D’Andrea VD, Gourisankar S, Dykhuizen EC, Crabtree GR. Chemical Inhibitors of a Selective SWI/SNF Function Synergize with ATR Inhibition in Cancer Cell Killing. ACS Chem Biol 2020; 15:1685-1696. [PMID: 32369697 DOI: 10.1021/acschembio.0c00312] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
SWI/SNF (BAF) complexes are a diverse family of ATP-dependent chromatin remodelers produced by combinatorial assembly that are mutated in and thought to contribute to 20% of human cancers and a large number of neurologic diseases. The gene-activating functions of BAF complexes are essential for viability of many cell types, limiting the development of small molecule inhibitors. To circumvent the potential toxicity of SWI/SNF inhibition, we identified small molecules that inhibit the specific repressive function of these complexes but are relatively nontoxic and importantly synergize with ATR inhibitors in killing cancer cells. Our studies suggest an avenue for therapeutic enhancement of ATR/ATM inhibition and provide evidence for chemical synthetic lethality of BAF complexes as a therapeutic strategy in cancer.
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Affiliation(s)
- Emma J. Chory
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
- Departments of Developmental Biology and Pathology, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Jacob G. Kirkland
- Departments of Developmental Biology and Pathology, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Chiung-Ying Chang
- Departments of Developmental Biology and Pathology, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Vincent D. D’Andrea
- Departments of Developmental Biology and Pathology, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Sai Gourisankar
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
- Departments of Developmental Biology and Pathology, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Emily C. Dykhuizen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, United States
| | - Gerald R. Crabtree
- Departments of Developmental Biology and Pathology, Stanford University School of Medicine, Stanford, California 94305, United States
- Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, United States
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Ciechomska IA, Jayaprakash C, Maleszewska M, Kaminska B. Histone Modifying Enzymes and Chromatin Modifiers in Glioma Pathobiology and Therapy Responses. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1202:259-279. [PMID: 32034718 DOI: 10.1007/978-3-030-30651-9_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Signal transduction pathways directly communicate and transform chromatin to change the epigenetic landscape and regulate gene expression. Chromatin acts as a dynamic platform of signal integration and storage. Histone modifications and alteration of chromatin structure play the main role in chromatin-based gene expression regulation. Alterations in genes coding for histone modifying enzymes and chromatin modifiers result in malfunction of proteins that regulate chromatin modification and remodeling. Such dysregulations culminate in profound changes in chromatin structure and distorted patterns of gene expression. Gliomagenesis is a multistep process, involving both genetic and epigenetic alterations. Recent applications of next generation sequencing have revealed that many chromatin regulation-related genes, including ATRX, ARID1A, SMARCA4, SMARCA2, SMARCC2, BAF155 and hSNF5 are mutated in gliomas. In this review we summarize newly identified mechanisms affecting expression or functions of selected histone modifying enzymes and chromatin modifiers in gliomas. We focus on selected examples of pathogenic mechanisms involving ATRX, histone methyltransferase G9a, histone acetylases/deacetylases and chromatin remodeling complexes SMARCA2/4. We discuss the impact of selected epigenetics alterations on glioma pathobiology, signaling and therapeutic responses. We assess the attempts of targeting defective pathways with new inhibitors.
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Affiliation(s)
- Iwona A Ciechomska
- Laboratory of Molecular Neurobiology, Neurobiology Center, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Chinchu Jayaprakash
- Laboratory of Molecular Neurobiology, Neurobiology Center, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Marta Maleszewska
- Laboratory of Molecular Neurobiology, Neurobiology Center, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Bozena Kaminska
- Laboratory of Molecular Neurobiology, Neurobiology Center, Nencki Institute of Experimental Biology, Warsaw, Poland.
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Hasan N, Ahuja N. The Emerging Roles of ATP-Dependent Chromatin Remodeling Complexes in Pancreatic Cancer. Cancers (Basel) 2019; 11:E1859. [PMID: 31769422 PMCID: PMC6966483 DOI: 10.3390/cancers11121859] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 02/08/2023] Open
Abstract
Pancreatic cancer is an aggressive cancer with low survival rates. Genetic and epigenetic dysregulation has been associated with the initiation and progression of pancreatic tumors. Multiple studies have pointed to the involvement of aberrant chromatin modifications in driving tumor behavior. ATP-dependent chromatin remodeling complexes regulate chromatin structure and have critical roles in stem cell maintenance, development, and cancer. Frequent mutations and chromosomal aberrations in the genes associated with subunits of the ATP-dependent chromatin remodeling complexes have been detected in different cancer types. In this review, we summarize the current literature on the genomic alterations and mechanistic studies of the ATP-dependent chromatin remodeling complexes in pancreatic cancer. Our review is focused on the four main subfamilies: SWItch/sucrose non-fermentable (SWI/SNF), imitation SWI (ISWI), chromodomain-helicase DNA-binding protein (CHD), and INOsitol-requiring mutant 80 (INO80). Finally, we discuss potential novel treatment options that use small molecules to target these complexes.
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Affiliation(s)
| | - Nita Ahuja
- Department of Surgery, Yale University School of Medicine, New Haven, CT 06520, USA;
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10
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Muthuswami R, Bailey L, Rakesh R, Imbalzano AN, Nickerson JA, Hockensmith JW. BRG1 is a prognostic indicator and a potential therapeutic target for prostate cancer. J Cell Physiol 2019; 234:15194-15205. [PMID: 30667054 PMCID: PMC6563042 DOI: 10.1002/jcp.28161] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 01/04/2019] [Indexed: 02/06/2023]
Abstract
Brahma-related gene 1 (BRG1) is one of two mutually exclusive ATPases that function as the catalytic subunit of human SWItch/Sucrose NonFermentable (SWI/SNF) chromatin remodeling enzymes. BRG1 has been identified as a tumor suppressor in some cancer types but has been shown to be expressed at elevated levels, relative to normal tissue, in other cancers. Using TCGA (The Cancer Genome Atlas) prostate cancer database, we determined that BRG1 mRNA and protein expression is elevated in prostate tumors relative to normal prostate tissue. Only 3 of 491 (0.6%) sequenced tumors showed amplification of the locus or mutation in the protein coding sequence, arguing against the idea that elevated expression due to amplification or expression of a mutant BRG1 protein is associated with prostate cancer. Kaplan-Meier survival curves showed that BRG1 expression in prostate tumors inversely correlated with survival. However, BRG1 expression did not correlate with Gleason score/International Society of Urological Pathology (ISUP) Grade Group, indicating it is an independent predictor of tumor progression/patient outcome. To experimentally assess BRG1 as a possible therapeutic target, we treated prostate cancer cells with a biologic inhibitor called ADAADi (active DNA-dependent ATPase A Domain inhibitor) that targets the activity of the SNF2 family of ATPases in biochemical assays but showed specificity for BRG1 in prior tissue culture experiments. The inhibitor decreased prostate cancer cell proliferation and induced apoptosis. When directly injected into xenografts established by injection of prostate cancer cells in mouse flanks, the inhibitor decreased tumor growth and increased survival. These results indicate the efficacy of pursuing BRG1 as both an indicator of patient outcome and as a therapeutic target.
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Affiliation(s)
- Rohini Muthuswami
- Department of Biochemistry and Molecular GeneticsUniversity of Virginia School of MedicineCharlottesvilleVirginia,School of Life Sciences, Jawaharlal Nehru UniversityNew DelhiIndia
| | - LeeAnn Bailey
- Department of Biochemistry and Molecular GeneticsUniversity of Virginia School of MedicineCharlottesvilleVirginia
| | | | - Anthony N. Imbalzano
- Department of Biochemistry and Molecular PharmacologyUniversity of Massachusetts Medical SchoolWorcesterMassachusetts
| | - Jeffrey A. Nickerson
- Department of PediatricsUniversity of Massachusetts Medical SchoolWorcesterMassachusetts
| | - Joel W. Hockensmith
- Department of Biochemistry and Molecular GeneticsUniversity of Virginia School of MedicineCharlottesvilleVirginia
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11
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Zernickel E, Sak A, Riaz A, Klein D, Groneberg M, Stuschke M. Targeting of BRM Sensitizes BRG1-Mutant Lung Cancer Cell Lines to Radiotherapy. Mol Cancer Ther 2018; 18:656-666. [PMID: 30478150 DOI: 10.1158/1535-7163.mct-18-0067] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 06/30/2018] [Accepted: 11/15/2018] [Indexed: 11/16/2022]
Abstract
Targeting of epigenetic regulators as the chromatin remodeler SWI/SNF is proving to be a promising therapeutic strategy for individualized treatment of cancer patients. Here, we tested whether targeting one of the two mutually exclusive subdomains of the SWI/SNF complex BRM/SMARCA2 can sensitize specifically non-small cell lung carcinoma (NSCLC) cells with mutations in the other subunit BRG1/SMARCA4 toward ionizing radiation (IR). Knockdown of BRM with siRNA or shRNA and its consequences for radiation sensitivity as measured by clonogenic survival and plaque-monolayer control was studied in different NSCLC lines with or without BRG1 mutations and in primary fibroblasts. Furthermore, the effect on double-strand break (DSB) repair markers measured by immunofluorescence staining of 53BP1-, γ-H2AX-, and Rad51-foci was investigated. BRG1-mutated cell lines showed an increased surviving fraction compared with BRG1 proficient cells. Depletion of BRM (i) leads to a decreased proliferation rate and plating efficiency specifically in BRG1-mutated cells, (ii) specifically sensitized BRG1-mutant NSCLC cells toward IR as characterized by a survival reducing factor of 0.63 [95% confidence interval (CI), 0.57-0.69] in the dose range between 2 and 6 Gy, and (iii) decreased the tumor control doses after daily fractionation at 4 Gy in BRG1-mutant NSCLC cell lines A549 and H1299 in minimonolayers by 9.9% ± 1.3% and 13.6% ± 1.8%, respectively. In addition, an increase of residual Rad51-foci at 24 hours after irradiation in BRG1-mutant cells was demonstrated. Therefore, targeting of BRM in combination with radiotherapy is supposed to improve the therapeutic outcome of lung cancer patients harboring BRG1 mutations.The present study shows that the moderate radioresponsiveness of NSCLC cells with BRG1 mutations can be increased upon BRM depletion that is associated with a prolonged Rad51-foci prevalence at DNA DSBs.
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Affiliation(s)
- Erika Zernickel
- Department of Radiotherapy, University of Duisburg-Essen, University Hospital, Essen, Germany.
| | - Ali Sak
- Department of Radiotherapy, University of Duisburg-Essen, University Hospital, Essen, Germany
| | - Assad Riaz
- Department of Radiotherapy, University of Duisburg-Essen, University Hospital, Essen, Germany
| | - Diana Klein
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen, University Hospital, Essen, Germany
| | - Michael Groneberg
- Department of Radiotherapy, University of Duisburg-Essen, University Hospital, Essen, Germany
| | - Martin Stuschke
- Department of Radiotherapy, University of Duisburg-Essen, University Hospital, Essen, Germany
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Wu Q, Madany P, Dobson JR, Schnabl JM, Sharma S, Smith TC, van Wijnen AJ, Stein JL, Lian JB, Stein GS, Muthuswami R, Imbalzano AN, Nickerson JA. The BRG1 chromatin remodeling enzyme links cancer cell metabolism and proliferation. Oncotarget 2018; 7:38270-38281. [PMID: 27223259 PMCID: PMC5122388 DOI: 10.18632/oncotarget.9505] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 05/01/2016] [Indexed: 12/20/2022] Open
Abstract
Cancer cells reprogram cellular metabolism to meet the demands of growth. Identification of the regulatory machinery that regulates cancer-specific metabolic changes may open new avenues for anti-cancer therapeutics. The epigenetic regulator BRG1 is a catalytic ATPase for some mammalian SWI/SNF chromatin remodeling enzymes. BRG1 is a well-characterized tumor suppressor in some human cancers, but is frequently overexpressed without mutation in other cancers, including breast cancer. Here we demonstrate that BRG1 upregulates de novo lipogenesis and that this is crucial for cancer cell proliferation. Knockdown of BRG1 attenuates lipid synthesis by impairing the transcription of enzymes catalyzing fatty acid and lipid synthesis. Remarkably, exogenous addition of palmitate, the key intermediate in fatty acid synthesis, rescued the cancer cell proliferation defect caused by BRG1 knockdown. Our work suggests that targeting BRG1 to reduce lipid metabolism and, thereby, to reduce proliferation, has promise for epigenetic therapy in triple negative breast cancer.
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Affiliation(s)
- Qiong Wu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Pasil Madany
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jason R Dobson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jake M Schnabl
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Soni Sharma
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Tara C Smith
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Andre J van Wijnen
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Janet L Stein
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, WA, USA
| | - Jane B Lian
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, WA, USA
| | - Gary S Stein
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, WA, USA
| | - Rohini Muthuswami
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
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13
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Wu Q, Sharma S, Cui H, LeBlanc SE, Zhang H, Muthuswami R, Nickerson JA, Imbalzano AN. Targeting the chromatin remodeling enzyme BRG1 increases the efficacy of chemotherapy drugs in breast cancer cells. Oncotarget 2017; 7:27158-75. [PMID: 27029062 PMCID: PMC5053639 DOI: 10.18632/oncotarget.8384] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 03/16/2016] [Indexed: 12/31/2022] Open
Abstract
Brahma related gene product 1 (BRG1) is an ATPase that drives the catalytic activity of a subset of the mammalian SWI/SNF chromatin remodeling enzymes. BRG1 is overexpressed in most human breast cancer tumors without evidence of mutation and is required for breast cancer cell proliferation. We demonstrate that knockdown of BRG1 sensitized triple negative breast cancer cells to chemotherapeutic drugs used to treat breast cancer. An inhibitor of the BRG1 bromodomain had no effect on breast cancer cell viability, but an inhibitory molecule that targets the BRG1 ATPase activity recapitulated the increased drug efficacy observed in the presence of BRG1 knockdown. We further demonstrate that inhibition of BRG1 ATPase activity blocks the induction of ABC transporter genes by these chemotherapeutic drugs and that BRG1 binds to ABC transporter gene promoters. This inhibition increased intracellular concentrations of the drugs, providing a likely mechanism for the increased chemosensitivity. Since ABC transporters and their induction by chemotherapy drugs are a major cause of chemoresistance and treatment failure, these results support the idea that targeting the enzymatic activity of BRG1 would be an effective adjuvant therapy for breast cancer.
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Affiliation(s)
- Qiong Wu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Soni Sharma
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Hang Cui
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA.,Abace Biotech Co Ltd., Yi Zhuang Biomedical Park, BDA, Beijing, China
| | - Scott E LeBlanc
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Hong Zhang
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Rohini Muthuswami
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
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Wu Q, Lian JB, Stein JL, Stein GS, Nickerson JA, Imbalzano AN. The BRG1 ATPase of human SWI/SNF chromatin remodeling enzymes as a driver of cancer. Epigenomics 2017; 9:919-931. [PMID: 28521512 PMCID: PMC5705788 DOI: 10.2217/epi-2017-0034] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mammalian SWI/SNF enzymes are ATP-dependent remodelers of chromatin structure. These multisubunit enzymes are heterogeneous in composition; there are two catalytic ATPase subunits, BRM and BRG1, that are mutually exclusive, and additional subunits are incorporated in a combinatorial manner. Recent findings indicate that approximately 20% of human cancers contain mutations in SWI/SNF enzyme subunits, leading to the conclusion that the enzyme subunits are critical tumor suppressors. However, overexpression of specific subunits without apparent mutation is emerging as an alternative mechanism by which cellular transformation may occur. Here we highlight recent evidence linking elevated expression of the BRG1 ATPase to tissue-specific cancers and work suggesting that inhibiting BRG1 may be an effective therapeutic strategy.
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Affiliation(s)
- Qiong Wu
- Department of Pediatrics, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Jane B Lian
- Department of Biochemistry, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - Janet L Stein
- Department of Biochemistry, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - Gary S Stein
- Department of Biochemistry, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - Jeffrey A Nickerson
- Department of Pediatrics, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Anthony N Imbalzano
- Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
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15
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Nickerson JA, Wu Q, Imbalzano AN. Mammalian SWI/SNF Enzymes and the Epigenetics of Tumor Cell Metabolic Reprogramming. Front Oncol 2017; 7:49. [PMID: 28421159 PMCID: PMC5378717 DOI: 10.3389/fonc.2017.00049] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 03/09/2017] [Indexed: 01/27/2023] Open
Abstract
Tumor cells reprogram their metabolism to survive and grow in a challenging microenvironment. Some of this reprogramming is performed by epigenetic mechanisms. Epigenetics is in turn affected by metabolism; chromatin modifying enzymes are dependent on substrates that are also key metabolic intermediates. We have shown that the chromatin remodeling enzyme Brahma-related gene 1 (BRG1), an epigenetic regulator, is necessary for rapid breast cancer cell proliferation. The mechanism for this requirement is the BRG1-dependent transcription of key lipogenic enzymes and regulators. Reduction in lipid synthesis lowers proliferation rates, which can be restored by palmitate supplementation. This work has established BRG1 as an attractive target for breast cancer therapy. Unlike genetic alterations, epigenetic mechanisms are reversible, promising gentler therapies without permanent off-target effects at distant sites.
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Affiliation(s)
- Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Qiong Wu
- Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
| | - Anthony N Imbalzano
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
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16
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Sharma T, Bansal R, Haokip DT, Goel I, Muthuswami R. SMARCAL1 Negatively Regulates C-Myc Transcription By Altering The Conformation Of The Promoter Region. Sci Rep 2015; 5:17910. [PMID: 26648259 PMCID: PMC4673416 DOI: 10.1038/srep17910] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 11/09/2015] [Indexed: 12/18/2022] Open
Abstract
SMARCAL1, a member of the SWI2/SNF2 protein family, stabilizes replication forks during DNA damage. In this manuscript, we provide the first evidence that SMARCAL1 is also a transcriptional co-regulator modulating the expression of c-Myc, a transcription factor that regulates 10-15% genes in the human genome. BRG1, SMARCAL1 and RNAPII were found localized onto the c-myc promoter. When HeLa cells were serum starved, the occupancy of SMARCAL1 on the c-myc promoter increased while that of BRG1 and RNAPII decreased correlating with repression of c-myc transcription. Using Active DNA-dependent ATPase A Domain (ADAAD), the bovine homolog of SMARCAL1, we show that the protein can hydrolyze ATP using a specific region upstream of the CT element of the c-myc promoter as a DNA effector. The energy, thereby, released is harnessed to alter the conformation of the promoter DNA. We propose that SMARCAL1 negatively regulates c-myc transcription by altering the conformation of its promoter region during differentiation.
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Affiliation(s)
| | - Ritu Bansal
- School of Life Sciences, JNU, New Delhi 110067
| | | | - Isha Goel
- School of Life Sciences, JNU, New Delhi 110067
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17
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Dutta P, Tanti GK, Sharma S, Goswami SK, Komath SS, Mayo MW, Hockensmith JW, Muthuswami R. Global epigenetic changes induced by SWI2/SNF2 inhibitors characterize neomycin-resistant mammalian cells. PLoS One 2012; 7:e49822. [PMID: 23209606 PMCID: PMC3509132 DOI: 10.1371/journal.pone.0049822] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 10/17/2012] [Indexed: 11/24/2022] Open
Abstract
Background Previously, we showed that aminoglycoside phosphotransferases catalyze the formation of a specific inhibitor of the SWI2/SNF2 proteins. Aminoglycoside phosphotransferases, for example neomycin-resistant genes, are used extensively as selection markers in mammalian transfections as well as in transgenic studies. However, introduction of the neomycin-resistant gene is fraught with variability in gene expression. We hypothesized that the introduction of neomycin-resistant genes into mammalian cells results in inactivation of SWI2/SNF2 proteins thereby leading to global epigenetic changes. Methodology Using fluorescence spectroscopy we have shown that the inhibitor, known as Active DNA-dependent ATPase ADomain inhibitor (ADAADi), binds to the SWI2/SNF2 proteins in the absence as well as presence of ATP and DNA. This binding occurs via a specific region known as Motif Ia leading to a conformational change in the SWI2/SNF2 proteins that precludes ATP hydrolysis. ADAADi is produced from a plethora of aminoglycosides including G418 and Streptomycin, two commonly used antibiotics in mammalian cell cultures. Mammalian cells are sensitive to ADAADi; however, cells stably transfected with neomycin-resistant genes are refractory to ADAADi. In resistant cells, endogenous SWI2/SNF2 proteins are inactivated which results in altered histone modifications. Microarray data shows that the changes in the epigenome are reflected in altered gene expression. The microarray data was validated using real-time PCR. Finally, we show that the epigenetic changes are quantized. Significance The use of neomycin-resistant genes revolutionized mammalian transfections even though questions linger about efficacy. In this study, we have demonstrated that selection of neomycin-resistant cells results in survival of only those cells that have undergone epigenetic changes, and therefore, data obtained using these resistant genes as selection markers need to be cautiously evaluated.
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Affiliation(s)
- Popy Dutta
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Goutam Kumar Tanti
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Soni Sharma
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Shyamal K. Goswami
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Sneha Sudha Komath
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Marty W. Mayo
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, United States of America
| | - Joel W. Hockensmith
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail: (JWH); (RM)
| | - Rohini Muthuswami
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
- * E-mail: (JWH); (RM)
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18
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Felle M, Exler JH, Merkl R, Dachauer K, Brehm A, Grummt I, Längst G. DNA sequence encoded repression of rRNA gene transcription in chromatin. Nucleic Acids Res 2010; 38:5304-14. [PMID: 20421213 PMCID: PMC2938192 DOI: 10.1093/nar/gkq263] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Eukaryotic genomes are packaged into nucleosomes that occlude DNA from interacting with most DNA-binding proteins. Nucleosome positioning and chromatin organization is critical for gene regulation. We have investigated the mechanism by which nucleosomes are positioned at the promoters of active and silent rRNA genes (rDNA). The reconstitution of nucleosomes on rDNA results in sequence-dependent nucleosome positioning at the rDNA promoter that mimics the chromatin structure of silent rRNA genes in vivo, suggesting that active mechanisms are required to reorganize chromatin structure upon gene activation. Nucleosomes are excluded from positions observed at active rRNA genes, resulting in transcriptional repression on chromatin. We suggest that the repressed state is the default chromatin organization of the rDNA and gene activation requires ATP-dependent chromatin remodelling activities that move the promoter-bound nucleosome about 22-bp upstream. We suggest that nucleosome remodelling precedes promoter-dependent transcriptional activation as specific inhibition of ATP-dependent chromatin remodelling suppresses the initiation of RNA Polymerase I transcription in vitro. Once initiated, RNA Polymerase I is capable of elongating through reconstituted chromatin without apparent displacement of the nucleosomes. The results reveal the functional cooperation of DNA sequence and chromatin remodelling complexes in nucleosome positioning and in establishing the epigenetic active or silent state of rRNA genes.
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Affiliation(s)
- Max Felle
- Institut für Biochemie III, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
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19
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Hinoue T, Weisenberger DJ, Pan F, Campan M, Kim M, Young J, Whitehall VL, Leggett BA, Laird PW. Analysis of the association between CIMP and BRAF in colorectal cancer by DNA methylation profiling. PLoS One 2009; 4:e8357. [PMID: 20027224 PMCID: PMC2791229 DOI: 10.1371/journal.pone.0008357] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Accepted: 11/20/2009] [Indexed: 12/15/2022] Open
Abstract
A CpG island methylator phenotype (CIMP) is displayed by a distinct subset of colorectal cancers with a high frequency of DNA hypermethylation in a specific group of CpG islands. Recent studies have shown that an activating mutation of BRAF (BRAFV600E) is tightly associated with CIMP, raising the question of whether BRAFV600E plays a causal role in the development of CIMP or whether CIMP provides a favorable environment for the acquisition of BRAFV600E. We employed Illumina GoldenGate DNA methylation technology, which interrogates 1,505 CpG sites in 807 different genes, to further study this association. We first examined whether expression of BRAFV600E causes DNA hypermethylation by stably expressing BRAFV600E in the CIMP-negative, BRAF wild-type COLO 320DM colorectal cancer cell line. We determined 100 CIMP-associated CpG sites and examined changes in DNA methylation in eight stably transfected clones over multiple passages. We found that BRAFV600E is not sufficient to induce CIMP in our system. Secondly, considering the alternative possibility, we identified genes whose DNA hypermethylation was closely linked to BRAFV600E and CIMP in 235 primary colorectal tumors. Interestingly, genes that showed the most significant link include those that mediate various signaling pathways implicated in colorectal tumorigenesis, such as BMP3 and BMP6 (BMP signaling), EPHA3, KIT, and FLT1 (receptor tyrosine kinases) and SMO (Hedgehog signaling). Furthermore, we identified CIMP-dependent DNA hypermethylation of IGFBP7, which has been shown to mediate BRAFV600E-induced cellular senescence and apoptosis. Promoter DNA hypermethylation of IGFBP7 was associated with silencing of the gene. CIMP-specific inactivation of BRAFV600E-induced senescence and apoptosis pathways by IGFBP7 DNA hypermethylation might create a favorable context for the acquisition of BRAFV600E in CIMP+ colorectal cancer. Our data will be useful for future investigations toward understanding CIMP in colorectal cancer and gaining insights into the role of aberrant DNA hypermethylation in colorectal tumorigenesis.
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Affiliation(s)
- Toshinori Hinoue
- USC Epigenome Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Department of Surgery and Department of Biochemistry and Molecular Biology, USC/Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Daniel J. Weisenberger
- USC Epigenome Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Fei Pan
- USC Epigenome Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Mihaela Campan
- Department of Surgery and Department of Biochemistry and Molecular Biology, USC/Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Myungjin Kim
- Department of Surgery and Department of Biochemistry and Molecular Biology, USC/Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Joanne Young
- Familial Cancer Laboratory, Queensland Institute of Medical Research, Herston, Queensland, Australia
- University of Queensland School of Medicine, Herston, Queensland, Australia
| | - Vicki L. Whitehall
- Conjoint Gastroenterology Laboratory, Clinical Research Centre, Royal Brisbane and Women's Hospital Research Foundation, Herston, Queensland, Australia
| | - Barbara A. Leggett
- Conjoint Gastroenterology Laboratory, Clinical Research Centre, Royal Brisbane and Women's Hospital Research Foundation, Herston, Queensland, Australia
| | - Peter W. Laird
- USC Epigenome Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Department of Surgery and Department of Biochemistry and Molecular Biology, USC/Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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20
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Nongkhlaw M, Dutta P, Hockensmith JW, Komath SS, Muthuswami R. Elucidating the mechanism of DNA-dependent ATP hydrolysis mediated by DNA-dependent ATPase A, a member of the SWI2/SNF2 protein family. Nucleic Acids Res 2009; 37:3332-41. [PMID: 19324887 PMCID: PMC2691824 DOI: 10.1093/nar/gkp178] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The active DNA-dependent ATPase A domain (ADAAD), a member of the SWI2/SNF2 family, has been shown to bind DNA in a structure-specific manner, recognizing DNA molecules possessing double-stranded to single-stranded transition regions leading to ATP hydrolysis. Extending these studies we have delineated the structural requirements of the DNA effector for ADAAD and have shown that the single-stranded and double-stranded regions both contribute to binding affinity while the double-stranded region additionally plays a role in determining the rate of ATP hydrolysis. We have also investigated the mechanism of interaction of DNA and ATP with ADAAD and shown that each can interact independently with ADAAD in the absence of the other. Furthermore, the protein can bind to dsDNA as well as ssDNA molecules. However, the conformation change induced by the ssDNA is different from the conformational change induced by stem-loop DNA (slDNA), thereby providing an explanation for the observed ATP hydrolysis only in the presence of the double-stranded:single-stranded transition (i.e. slDNA).
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Affiliation(s)
- Macmillan Nongkhlaw
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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21
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Melnick AM, Adelson K, Licht JD. The theoretical basis of transcriptional therapy of cancer: can it be put into practice? J Clin Oncol 2005; 23:3957-70. [PMID: 15867201 DOI: 10.1200/jco.2005.14.498] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Aberrant gene silencing is a frequent event in cancer and plays a critical role in the molecular pathogenesis of malignant transformation. The two major mechanisms of silencing in cancer include transcriptional repression by mutated or aberrantly expressed transcription factors, and aberrant epigenetic silencing by hypermethylation of tumor suppressor or DNA repair-related genes. Both of these mechanisms require the activities of multiprotein chromatin remodeling and modifying machines, several of which may be mutated in cancer. The end result is genetic reprogramming of cells to express combinations of genes that confer the neoplastic phenotype. Recent discoveries in transcriptional biochemistry and gene regulation indicate that therapeutic agents can be engineered to specifically target these mechanisms. We provide a framework for the clinical or translational scientist to consider how such drugs might be developed and what their impact might be on restoring cells to normal genetic programming.
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Affiliation(s)
- Ari M Melnick
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA
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22
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Abstract
Molecular lesions of genes encoding for transcriptional regulatory proteins are common oncogenic events in hematologic malignancies. Transcriptional activation and repression both occur by virtue of the choreographed recruitment of multisubunit cofactor complexes to target gene loci. As a consequence, the three-dimensional structure of the target gene is altered and its potential to support transcription is increased or decreased. The complexity of the transcriptional process offers a rich substrate for designing therapeutic agents. The objective of such 'transcription therapy' is to regain control over cohorts of target genes and restore the normal genetic and epigenetic programming of the cancer cell. The success of all-trans retinoic acid in the treatment of acute promyelocytic leukemia indicates that transcription therapy can be highly effective and safe. A classification scheme of these therapeutic strategies is proposed herein, which allows predictions to be made regarding specificity, efficacy, disease spectrum and side effects. This framework could help facilitate discussion of the mechanisms of action of transcription therapy drugs as well as the design of preclinical and clinical trials in the future.
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Affiliation(s)
- A Melnick
- Department of Developmental and Molecular Biology and Medical Oncology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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