1
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Qiu Y, Bai L, Zhao H, Mei X. Homoharringtonine enhances cytarabine-induced apoptosis in acute myeloid leukaemia by regulating the p38 MAPK/H2AX/Mcl-1 axis. BMC Cancer 2024; 24:520. [PMID: 38658865 PMCID: PMC11044605 DOI: 10.1186/s12885-024-12286-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 04/18/2024] [Indexed: 04/26/2024] Open
Abstract
Acute myeloid leukaemia (AML) is a fatal haematopoietic malignancy and is treated with the conventional combination of cytarabine (Ara-C) and daunorubicin (Dau). The survival rate of AML patients is lower due to the cardiotoxicity of daunorubicin. Clinically, homoharringtonine (HHT) plus Ara-C has been reported to be equally effective as Dau plus Ara-C in some types of AML patients with less toxic effects. We utilized the clinical use of homoharringtonine in combination with Ara-C to test its combination mechanism. We found that the insensitivity of AML cells to cytarabine-induced apoptosis is associated with increased Mcl-1 stability and p38 inactivation. HHT downregulates Mcl-1, phosphorylates H2AX and induces apoptosis by activating p38 MAPK. Inactivation of p38 through inhibitors and siRNA blocks apoptosis, H2AX phosphorylation and Mcl-1 reduction. HHT enhances Ara-C activation of the p38 MAPK signalling pathway, overcoming Ara-C tolerance to cell apoptosis by regulating the p38/H2AX/Mcl-1 axis. The optimal ratio of HHT to Ara-C for synergistic lethality in AML cells is 1:4 (M/M). HHT synergistically induces apoptosis in combination with Ara-C in vitro and prolongs the survival of xenografts. We provide a new mechanism for AML treatment by regulating the p38 MAPK/H2AX/Mcl-1 axis to improve cytarabine therapy.
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Affiliation(s)
- Yang Qiu
- School of Pharmacy, Jinzhou Medical University, Jinzhou, 121001, Liaoning, China.
- Liaoning Provincial Collaborative Innovation Center for Medical Testing and Drug Research, Jinzhou Medical University, Jinzhou, 121001, Liaoning, China.
- Liaoning Provincial Key Laboratory of Marine Bioactive Substances, Jinzhou Medical University, Jinzhou, 121001, Liaoning, China.
- Technological Innovation Center of Liaoning Pharmaceutical Action and Quality Evaluation, Jinzhou Medical University, Jinzhou, 121001, Liaoning, China.
| | - Lu Bai
- Affiliated Third Hospital of Jinzhou Medical University, Jinzhou, 121001, Liaoning, China
| | - Haosen Zhao
- Affiliated Third Hospital of Jinzhou Medical University, Jinzhou, 121001, Liaoning, China
| | - Xifan Mei
- Jinzhou Medical University, Jinzhou, 121001, Liaoning, China.
- Liaoning Provincial Collaborative Innovation Center for Medical Testing and Drug Research, Jinzhou Medical University, Jinzhou, 121001, Liaoning, China.
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2
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Newell S, van der Watt PJ, Leaner VD. Therapeutic targeting of nuclear export and import receptors in cancer and their potential in combination chemotherapy. IUBMB Life 2024; 76:4-25. [PMID: 37623925 PMCID: PMC10952567 DOI: 10.1002/iub.2773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 07/03/2023] [Indexed: 08/26/2023]
Abstract
Systemic modalities are crucial in the management of disseminated malignancies and liquid tumours. However, patient responses and tolerability to treatment are generally poor and those that enter remission often return with refractory disease. Combination therapies provide a methodology to overcome chemoresistance mechanisms and address dose-limiting toxicities. A deeper understanding of tumorigenic processes at the molecular level has brought a targeted therapy approach to the forefront of cancer research, and novel cancer biomarkers are being identified at a rapid rate, with some showing potential therapeutic benefits. The Karyopherin superfamily of proteins is soluble receptors that mediate nucleocytoplasmic shuttling of proteins and RNAs, and recently, nuclear transport receptors have been recognized as novel anticancer targets. Inhibitors against nuclear export have been approved for clinical use against certain cancer types, whereas inhibitors against nuclear import are in preclinical stages of investigation. Mechanistically, targeting nucleocytoplasmic shuttling has shown to abrogate oncogenic signalling and restore tumour suppressor functions through nuclear sequestration of relevant proteins and mRNAs. Hence, nuclear transport inhibitors display broad spectrum anticancer activity and harbour potential to engage in synergistic interactions with a wide array of cytotoxic agents and other targeted agents. This review is focussed on the most researched nuclear transport receptors in the context of cancer, XPO1 and KPNB1, and highlights how inhibitors targeting these receptors can enhance the therapeutic efficacy of standard of care therapies and novel targeted agents in a combination therapy approach. Furthermore, an updated review on the therapeutic targeting of lesser characterized karyopherin proteins is provided and resistance to clinically approved nuclear export inhibitors is discussed.
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Affiliation(s)
- Stella Newell
- Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
| | - Pauline J. van der Watt
- Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
- Institute of Infectious Diseases and Molecular Medicine, University of Cape TownCape TownSouth Africa
| | - Virna D. Leaner
- Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
- UCT/SAMRC Gynaecological Cancer Research CentreUniversity of Cape TownCape TownSouth Africa
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3
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Prabhu D, Ray U, Rajeev A, Joy R, George AT, George J, Raghavan SC, John F. Design and Synthesis of Ketenimine Sulfonamide Conjugates through Multicomponent Reactions; A Combined Cytotoxic Analysis and Computational Exploration. ACS OMEGA 2023; 8:38619-38631. [PMID: 37867708 PMCID: PMC10586297 DOI: 10.1021/acsomega.3c05816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 09/25/2023] [Indexed: 10/24/2023]
Abstract
Multicomponent reactions involving zwitterion generated from dimethyl acetylenedicarboxylate, aryl sulfonamide, and isocyanide to generate sulfonamide-conjugated ketenimines is reported. The synthetic strategy adopted is highly atom economical and stereoselective. Ketenimine sulfonamide analogues are key intermediates for further synthetic conversions to generate a combinatorial library of compounds. Furthermore, sulfonamide compounds are known to possess a broad spectrum of biological applications. All the novel molecules synthesized exhibit the potential to target the nonhomologous DNA end-joining (NHEJ) pathway with cytotoxic ability. Computational studies compliment the in vitro biological assays of the 8 small-molecule inhibitors. DNA double-strand breaks (DSBs) are considered as the most lethal among different DNA damages. NHEJ repairs about 70% of the DSBs generated in cells within mammals. The DNA-dependent protein kinase catalytic subunit is one of the PI3 kinases associated with NHEJ. Compounds DK01-DK08 were investigated for their ability to induce cancer cell death by treating with two leukemic cell lines where NHEJ is high. Results showed that bromoaryl (DK04)- and nitroaryl (DK05)-conjugated molecules showed excellent biological activity, having IC50 values of ∼2 μM in Nalm6 cell lines.
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Affiliation(s)
- Deepak
J. Prabhu
- Post
Graduate Research Department of Chemistry, Maharajas College, Ernakulam, Ernakulam, Kerala 682011, India
| | - Ujjayinee Ray
- Department
of Microbiology, Techno India University,
Kolkata, West Bengal 700091, India
| | - Anjaly Rajeev
- Post
Graduate and Research Department of Chemistry, Sacred Heart college (M.G University), Thevara, Kerala 682013, India
| | - Reshma Joy
- Post
Graduate and Research Department of Chemistry, Sacred Heart college (M.G University), Thevara, Kerala 682013, India
| | - Abi Thoppilan George
- Post
Graduate and Research Department of Chemistry, Sacred Heart college (M.G University), Thevara, Kerala 682013, India
| | - Jinu George
- Post
Graduate and Research Department of Chemistry, Sacred Heart college (M.G University), Thevara, Kerala 682013, India
| | - Sathees C. Raghavan
- Department
of Biochemistry, Indian Institute of Science, Bengaluru 560012, India
| | - Franklin John
- Post
Graduate and Research Department of Chemistry, Sacred Heart college (M.G University), Thevara, Kerala 682013, India
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4
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Ray U, Gopinatha VK, Sharma S, Goyary L, Choudhary B, Mantelingu K, Rangappa KS, Raghavan SC. Identification and characterization of mercaptopyrimidine-based small molecules as inhibitors of nonhomologous DNA end joining. FEBS J 2023; 290:796-820. [PMID: 36048168 DOI: 10.1111/febs.16615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 07/21/2022] [Accepted: 08/31/2022] [Indexed: 02/04/2023]
Abstract
Mercaptopyrimidine derivatives are heterocyclic compounds with potent biological activities including antiproliferative, antibacterial, and anti-inflammatory properties. The present study describes the synthesis and characterization of several mercaptopyrimidine derivatives through condensation of 5,6-diamino-2-mercaptopyrimidin-4-ol with various heterocyclic and aromatic aldehydes. Previous studies have shown that SCR7, synthesized from 5,6-diamino-2-mercaptopyrimidin-4-ol, induced cytotoxicity by targeting cancer cells by primarily inhibiting DNA Ligase IV involved in nonhomologous end joining, one of the major DNA double-strand break repair pathways. Inhibition of DNA repair pathways is considered as an important strategy for cancer therapy. Due to limitations of SCR7 in terms of IC50 in cancer cells, here we have designed, synthesized, and characterized potent derivatives of SCR7 using 5,6-diamino-2-mercaptopyrimidin-4-ol as the starting material. Several synthesized imine compounds exhibited significant improvement in inhibition of end joining and cytotoxicity up to 27-fold lower concentrations than SCR7. Among these, two compounds, SCR116 and SCR132, showed increased cancer cell death in a Ligase IV-dependent manner. Treatment with the compounds also led to reduction in V(D)J recombination efficiency, cell cycle arrest at G2/M phase, accumulation of double-strand breaks inside cells, and improved anti-cancer potential when combined with γ-radiation and radiomimetic drugs. Thus, we describe novel inhibitors of NHEJ with higher efficacy and potential, which can be developed as cancer therapeutics.
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Affiliation(s)
- Ujjayinee Ray
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Vindya K Gopinatha
- Department of Biochemistry, Indian Institute of Science, Bangalore, India.,Department of Studies in Chemistry, University of Mysore, India
| | - Shivangi Sharma
- Department of Biochemistry, Indian Institute of Science, Bangalore, India.,Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, India
| | - Laijau Goyary
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, India
| | | | - Kanchugarakoppal S Rangappa
- Department of Studies in Chemistry, University of Mysore, India.,Institution of Excellence, Vijnana Bhavana, University of Mysore, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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5
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Paranjape AM, Desai SS, Nishana M, Roy U, Nilavar NM, Mondal A, Kumari R, Radha G, Katapadi VK, Choudhary B, Raghavan SC. Nonamer dependent RAG cleavage at CpGs can explain mechanism of chromosomal translocations associated to lymphoid cancers. PLoS Genet 2022; 18:e1010421. [PMID: 36228010 PMCID: PMC9595545 DOI: 10.1371/journal.pgen.1010421] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 10/25/2022] [Accepted: 09/09/2022] [Indexed: 11/18/2022] Open
Abstract
Chromosomal translocations are considered as one of the major causes of lymphoid cancers. RAG complex, which is responsible for V(D)J recombination, can also cleave non-B DNA structures and cryptic RSSs in the genome leading to chromosomal translocations. The mechanism and factors regulating the illegitimate function of RAGs resulting in oncogenesis are largely unknown. Upon in silico analysis of 3760 chromosomal translocations from lymphoid cancer patients, we find that 93% of the translocation breakpoints possess adjacent cryptic nonamers (RAG binding sequences), of which 77% had CpGs in proximity. As a proof of principle, we show that RAGs can efficiently bind to cryptic nonamers present at multiple fragile regions and cleave at adjacent mismatches generated to mimic the deamination of CpGs. ChIP studies reveal that RAGs can indeed recognize these fragile sites on a chromatin context inside the cell. Finally, we show that AID, the cytidine deaminase, plays a significant role during the generation of mismatches at CpGs and reconstitute the process of RAG-dependent generation of DNA breaks both in vitro and inside the cells. Thus, we propose a novel mechanism for generation of chromosomal translocation, where RAGs bind to the cryptic nonamer sequences and direct cleavage at adjacent mismatch generated due to deamination of meCpGs or cytosines.
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Affiliation(s)
- Amita M. Paranjape
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Sagar S. Desai
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, India
- Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Mayilaadumveettil Nishana
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
- Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Urbi Roy
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Namrata M. Nilavar
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Amrita Mondal
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Rupa Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Gudapureddy Radha
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | | | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, India
- * E-mail: (BC); (SCR)
| | - Sathees C. Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
- * E-mail: (BC); (SCR)
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6
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A novel KU70-mutant human leukemic cell line generated using CRISPR-Cas9 shows increased sensitivity to DSB inducing agents and reduced NHEJ activity. Biochim Biophys Acta Gen Subj 2022; 1866:130246. [PMID: 36162731 DOI: 10.1016/j.bbagen.2022.130246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/10/2022] [Accepted: 09/19/2022] [Indexed: 11/21/2022]
Abstract
KU70 (XRCC6 gene in humans) is one of the proteins in the KU70-KU80 heterodimer which is the first component recruited to broken DNA ends during DNA double-strand break repair through nonhomologous end joining (NHEJ). Previous studies have shown that Ku70 deficient mouse cells are defective in NHEJ and V(D)J recombination. In contrast, heterozygous KU70 mutant human cell lines did not show any significant change in cell viability and sensitivity towards ionizing radiation. In this study, we used CRISPR-Cas9 technique to generate a KU70 mutant (heterozygous) human pre-B leukemic cell line (N6-KU70-2-DG). We observed that the N6-KU70-2-DG cells showed a prominent reduction in the expression of both KU70 mRNA and protein. The mutant cells showed reduced cell viability, increased sensitivity to DSB inducing agents such as ionizing radiation (IR) and etoposide, and increased number of unrepaired DSBs after exposure to IR. In addition, the mutant cells showed a reduction in the NHEJ activity and increased rate of microhomology mediated joining (MMEJ) activity. KU70 mutant cells also revealed enhanced level of senescence markers following irradiation. Thus, we report a novel KU70-mutant leukemic cell line (heterozygous) with reduced NHEJ, which is sensitive to DNA damaging agents, unlike the previously reported other KU heterozygous mutant cell lines.
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7
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Sora V, Papaleo E. Structural Details of BH3 Motifs and BH3-Mediated Interactions: an Updated Perspective. Front Mol Biosci 2022; 9:864874. [PMID: 35685242 PMCID: PMC9171138 DOI: 10.3389/fmolb.2022.864874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/13/2022] [Indexed: 11/18/2022] Open
Abstract
Apoptosis is a mechanism of programmed cell death crucial in organism development, maintenance of tissue homeostasis, and several pathogenic processes. The B cell lymphoma 2 (BCL2) protein family lies at the core of the apoptotic process, and the delicate balance between its pro- and anti-apoptotic members ultimately decides the cell fate. BCL2 proteins can bind with each other and several other biological partners through the BCL2 homology domain 3 (BH3), which has been also classified as a possible Short Linear Motif and whose distinctive features remain elusive even after decades of studies. Here, we aim to provide an updated overview of the structural features characterizing BH3s and BH3-mediated interactions (with a focus on human proteins), elaborating on the plasticity of BCL2 proteins and the motif properties. We also discussed the implication of these findings for the discovery of interactors of the BH3-binding groove of BCL2 proteins and the design of mimetics for therapeutic purposes.
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Affiliation(s)
- Valentina Sora
- Cancer Structural Biology, Danish Cancer Society Research Center, Copenhagen, Denmark
- Cancer Systems Biology, Section for Bioinformatics, Department of Health and Technology, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Elena Papaleo
- Cancer Structural Biology, Danish Cancer Society Research Center, Copenhagen, Denmark
- Cancer Systems Biology, Section for Bioinformatics, Department of Health and Technology, Technical University of Denmark, Kongens Lyngby, Denmark
- *Correspondence: Elena Papaleo, ,
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8
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Yu H, Wu S, Liu S, Li X, Gai Y, Lin H, Wang Y, Edwards H, Ge Y, Wang G. Venetoclax enhances DNA damage induced by XPO1 inhibitors: A novel mechanism underlying the synergistic antileukaemic effect in acute myeloid leukaemia. J Cell Mol Med 2022; 26:2646-2657. [PMID: 35355406 PMCID: PMC9077288 DOI: 10.1111/jcmm.17274] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 03/08/2022] [Accepted: 03/10/2022] [Indexed: 11/26/2022] Open
Abstract
Acute myeloid leukaemia (AML) is a highly heterogeneous haematologic malignancy with poor prognosis. We previously showed synergistic antileukaemic interaction between exportin 1 (XPO1) inhibitor KPT-330 (Selinexor) and Bcl-2 inhibitor venetoclax (ABT-199) in preclinical models of AML, which was partially meditated by Mcl-1, although the full mechanism of action remains unknown. In this study, using real-time RT-PCR and Western blot analysis, we show that inhibition of XPO1 via KPT-330 or KPT-8602 (Eltanexor) decreases the mRNA and protein levels of c-Myc, CHK1, WEE1, RAD51 and RRM2. KPT-330 and KPT-8602 induce DNA damage, as determined by alkaline comet assay. In addition, we demonstrate that venetoclax enhances KPT-330- and KPT-8602-induced DNA damage, likely through inhibition of DNA damage repair. This study provides new insight into the molecular mechanism underlying the synergistic antileukaemic activity between venetoclax and XPO1 inhibitors against AML. Our data support the clinical evaluation of this promising combination therapy for the treatment of AML.
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Affiliation(s)
- Hanxi Yu
- National Engineering Laboratory for AIDS VaccineKey Laboratory for Molecular Enzymology and Engineeringthe Ministry of EducationSchool of Life SciencesJilin UniversityChangchunChina
| | - Shuangshuang Wu
- National Engineering Laboratory for AIDS VaccineKey Laboratory for Molecular Enzymology and Engineeringthe Ministry of EducationSchool of Life SciencesJilin UniversityChangchunChina
| | - Shuang Liu
- National Engineering Laboratory for AIDS VaccineKey Laboratory for Molecular Enzymology and Engineeringthe Ministry of EducationSchool of Life SciencesJilin UniversityChangchunChina
| | - Xinyu Li
- National Engineering Laboratory for AIDS VaccineKey Laboratory for Molecular Enzymology and Engineeringthe Ministry of EducationSchool of Life SciencesJilin UniversityChangchunChina
| | - Yuqing Gai
- National Engineering Laboratory for AIDS VaccineKey Laboratory for Molecular Enzymology and Engineeringthe Ministry of EducationSchool of Life SciencesJilin UniversityChangchunChina
| | - Hai Lin
- Department of Hematology and Oncologythe First Hospital of Jilin UniversityChangchunChina
| | - Yue Wang
- Department of Pediatric Hematology and Oncologythe First Hospital of Jilin UniversityChangchunChina
| | - Holly Edwards
- Department of Oncology and Molecular Therapeutics ProgramBarbara Ann Karmanos Cancer InstituteWayne State University School of MedicineDetroitMichiganUSA
| | - Yubin Ge
- Department of Oncology and Molecular Therapeutics ProgramBarbara Ann Karmanos Cancer InstituteWayne State University School of MedicineDetroitMichiganUSA
| | - Guan Wang
- National Engineering Laboratory for AIDS VaccineKey Laboratory for Molecular Enzymology and Engineeringthe Ministry of EducationSchool of Life SciencesJilin UniversityChangchunChina
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9
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Depletion of RNASEH2 Activity Leads to Accumulation of DNA Double-strand Breaks and Reduced Cellular Survivability in T Cell Leukemia. J Mol Biol 2022; 434:167617. [DOI: 10.1016/j.jmb.2022.167617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 03/15/2022] [Accepted: 04/25/2022] [Indexed: 11/21/2022]
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10
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Dahal S, Siddiqua H, Katapadi VK, Iyer D, Raghavan SC. Characterization of G4 DNA formation in mitochondrial DNA and their potential role in mitochondrial genome instability. FEBS J 2021; 289:163-182. [PMID: 34228888 DOI: 10.1111/febs.16113] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/29/2021] [Accepted: 07/06/2021] [Indexed: 12/16/2022]
Abstract
Mitochondria possess their own genome which can be replicated independently of nuclear DNA. Mitochondria being the powerhouse of the cell produce reactive oxygen species, due to which the mitochondrial genome is frequently exposed to oxidative damage. Previous studies have demonstrated an association of mitochondrial deletions to aging and human disorders. Many of these deletions were present adjacent to non-B DNA structures. Thus, we investigate noncanonical structures associated with instability in mitochondrial genome. In silico studies revealed the presence of > 100 G-quadruplex motifs (of which 5 have the potential to form 3-plate G4 DNA), 23 inverted repeats, and 3 mirror repeats in the mitochondrial DNA (mtDNA). Further analysis revealed that among the deletion breakpoints from patients with mitochondrial disorders, majority are located at G4 DNA motifs. Interestingly, ~ 50% of the deletions were at base-pair positions 8271-8281, ~ 35% were due to deletion at 12362-12384, and ~ 12% due to deletion at 15516-15545. Formation of 3-plate G-quadruplex DNA structures at mitochondrial fragile regions was characterized using electromobility shift assay, circular dichroism (CD), and Taq polymerase stop assay. All 5 regions could fold into both intramolecular and intermolecular G-quadruplex structures in a KCl-dependent manner. G4 DNA formation was in parallel orientation, which was abolished in the presence of LiCl. The formation of G4 DNA affected both replication and transcription. Finally, immunolocalization of BG4 with MitoTracker confirmed the formation of G-quadruplex in mitochondrial genome. Thus, we characterize the formation of 5 different G-quadruplex structures in human mitochondrial region, which may contribute toward formation of mitochondrial deletions.
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Affiliation(s)
- Sumedha Dahal
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Humaira Siddiqua
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Vijeth K Katapadi
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Divyaanka Iyer
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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11
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Tatin X, Muggiolu G, Sauvaigo S, Breton J. Evaluation of DNA double-strand break repair capacity in human cells: Critical overview of current functional methods. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2021; 788:108388. [PMID: 34893153 DOI: 10.1016/j.mrrev.2021.108388] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 06/17/2021] [Accepted: 06/23/2021] [Indexed: 02/05/2023]
Abstract
DNA double-strand breaks (DSBs) are highly deleterious lesions, responsible for mutagenesis, chromosomal translocation or cell death. DSB repair (DSBR) is therefore a critical part of the DNA damage response (DDR) to restore molecular and genomic integrity. In humans, this process is achieved through different pathways with various outcomes. The balance between DSB repair activities varies depending on cell types, tissues or individuals. Over the years, several methods have been developed to study variations in DSBR capacity. Here, we mainly focus on functional techniques, which provide dynamic information regarding global DSB repair proficiency or the activity of specific pathways. These methods rely on two kinds of approaches. Indirect techniques, such as pulse field gel electrophoresis (PFGE), the comet assay and immunofluorescence (IF), measure DSB repair capacity by quantifying the time-dependent decrease in DSB levels after exposure to a DNA-damaging agent. On the other hand, cell-free assays and reporter-based methods directly track the repair of an artificial DNA substrate. Each approach has intrinsic advantages and limitations and despite considerable efforts, there is currently no ideal method to quantify DSBR capacity. All techniques provide different information and can be regarded as complementary, but some studies report conflicting results. Parameters such as the type of biological material, the required equipment or the cost of analysis may also limit available options. Improving currently available methods measuring DSBR capacity would be a major step forward and we present direct applications in mechanistic studies, drug development, human biomonitoring and personalized medicine, where DSBR analysis may improve the identification of patients eligible for chemo- and radiotherapy.
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Affiliation(s)
- Xavier Tatin
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France; LXRepair, 5 Avenue du Grand Sablon, 38700 La Tronche, France
| | | | - Sylvie Sauvaigo
- LXRepair, 5 Avenue du Grand Sablon, 38700 La Tronche, France
| | - Jean Breton
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France.
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12
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Gopalakrishnan V, Sharma S, Ray U, Manjunath M, Lakshmanan D, Vartak SV, Gopinatha VK, Srivastava M, Kempegowda M, Choudhary B, Raghavan SC. SCR7, an inhibitor of NHEJ can sensitize tumor cells to ionization radiation. Mol Carcinog 2021; 60:627-643. [PMID: 34192388 DOI: 10.1002/mc.23329] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 12/30/2022]
Abstract
Nonhomologous end joining (NHEJ), one of the major DNA double-strand break repair pathways, plays a significant role in cancer cell proliferation and resistance to radio and chemotherapeutic agents. Previously, we had described a small molecule inhibitor, SCR7, which inhibited NHEJ in a DNA Ligase IV dependent manner. Here, we report that SCR7 potentiates the effect of γ-radiation (IR) that induces DNA breaks as intermediates to eradicate cancer cells. Dose fractionation studies revealed that coadministration of SCR7 and IR (0.5 Gy) in mice Dalton's lymphoma (DLA) model led to a significant reduction in mice tumor cell proliferation, which was equivalent to that observed for 2 Gy dose when both solid and liquid tumor models were used. Besides, co-treatment with SCR7 and 1 Gy of IR further improved the efficacy. Notably, there was no significant change in blood parameters, kidney and liver functions upon combinatorial treatment of SCR7 and IR. Further, the co-treatment of SCR7 and IR resulted in a significant increase in unrepaired DSBs within cancer cells compared to either of the agent alone. Anatomy, histology, and other studies in tumor models confirmed the cumulative effects of both agents in activating apoptotic pathways to induce cytotoxicity by modulating DNA damage response and repair pathways. Thus, we report that SCR7 has the potential to reduce the side effects of radiotherapy by lowering its effective dose ex vivo and in mice tumor models, with implications in cancer therapy.
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Affiliation(s)
- Vidya Gopalakrishnan
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India.,Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, Karnataka, India.,Department of Zoology, St. Joseph's College (Autonomous), Irinjalakuda, Kerala, India
| | - Shivangi Sharma
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India.,Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, Karnataka, India
| | - Ujjayinee Ray
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Meghana Manjunath
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, Karnataka, India.,Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Divya Lakshmanan
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Supriya V Vartak
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Vindya K Gopinatha
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Mrinal Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India.,Tata Institute of Fundamental Research, Hyderabad, Telangana, India
| | | | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, Karnataka, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
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13
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Javadekar SM, Nilavar NM, Paranjape A, Das K, Raghavan SC. Characterization of G-quadruplex antibody reveals differential specificity for G4 DNA forms. DNA Res 2021; 27:5934508. [PMID: 33084858 PMCID: PMC7711166 DOI: 10.1093/dnares/dsaa024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 10/08/2020] [Indexed: 12/11/2022] Open
Abstract
Accumulating evidence suggests that human genome can fold into non-B DNA structures, when appropriate sequence and favourable conditions are present. Among these, G-quadruplexes (G4-DNA) are associated with gene regulation, chromosome fragility and telomere maintenance. Although several techniques are used in detecting such structures in vitro, understanding their intracellular existence has been challenging. Recently, an antibody, BG4, was described to study G4 structures within cells. Here, we characterize BG4 for its affinity towards G4-DNA, using several biochemical and biophysical tools. BG4 bound to G-rich DNA derived from multiple genes that form G-quadruplexes, unlike complementary C-rich or random sequences. BLI studies revealed robust binding affinity (Kd = 17.4 nM). Gel shift assays show BG4 binds to inter- and intramolecular G4-DNA, when it is in parallel orientation. Mere presence of G4-motif in duplex DNA is insufficient for antibody recognition. Importantly, BG4 can bind to G4-DNA within telomere sequence in a supercoiled plasmid. Finally, we show that BG4 binds to form efficient foci in four cell lines, irrespective of their lineage, demonstrating presence of G4-DNA in genome. Importantly, number of BG4 foci within the cells can be modulated, upon knockdown of G4-resolvase, WRN. Thus, we establish specificity of BG4 towards G4-DNA and discuss its potential applications.
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Affiliation(s)
- Saniya M Javadekar
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Namrata M Nilavar
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Amita Paranjape
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Kohal Das
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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14
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Ghosh D, Raghavan SC. Nonhomologous end joining: new accessory factors fine tune the machinery. Trends Genet 2021; 37:582-599. [PMID: 33785198 DOI: 10.1016/j.tig.2021.03.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/01/2021] [Accepted: 03/04/2021] [Indexed: 01/08/2023]
Abstract
Nonhomologous DNA end joining (NHEJ) is one of the major DNA double-strand break (DSB) repair pathways in eukaryotes. The well-known critical proteins involved in NHEJ include Ku70/80, DNA-PKcs, Artemis, DNA pol λ/μ, DNA ligase IV-XRCC4, and XLF. Recent studies have added a number of new proteins to the NHEJ repertoire namely paralog of XRCC4 and XLF (PAXX), modulator of retroviral infection (MRI)/ cell cycle regulator of NHEJ (CYREN), transactivation response DNA-binding protein (TARDBP) of 43 kDa (TDP-43), intermediate filament family orphan (IFFO1), ERCC excision repair 6 like 2 (ERCC6L2), and RNase H2. PAXX acts as a stabilizing factor for the main NHEJ components. MRI/CYREN seems to play a dual role stimulating NHEJ in the G1 phase of the cell cycle, while inhibiting the pathway in the S and G2 phases. TDP-43 can recruit the ligase IV-XRCC4 complex to the DSB sites and stimulate ligation in neuronal cells. RNase H2 excises out the ribonucleotides inserted during repair by DNA polymerase μ/TdT. This review provides a brief glimpse into how these new partners were discovered and their contribution to the mechanism and regulation of NHEJ.
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Affiliation(s)
- Dipayan Ghosh
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
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15
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Ray U, Raul SK, Gopinatha VK, Ghosh D, Rangappa KS, Mantelingu K, Raghavan SC. Identification and characterization of novel SCR7-based small-molecule inhibitor of DNA end-joining, SCR130 and its relevance in cancer therapeutics. Mol Carcinog 2020; 59:618-628. [PMID: 32189406 DOI: 10.1002/mc.23186] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/26/2020] [Accepted: 02/27/2020] [Indexed: 12/20/2022]
Abstract
Targeting DNA repair with small-molecule inhibitors is an attractive strategy for cancer therapy. Majority of DNA double-strand breaks in mammalian cells are repaired through nonhomologous end-joining (NHEJ). It has been shown that small-molecule inhibitors of NHEJ can block efficient repair inside cancer cells, leading to cell death. Previously, we have reported that SCR7, an inhibitor of NHEJ can induce tumor regression in mice. Later studies have shown that different forms of SCR7 can inhibit DNA end-joining in Ligase IV-dependent manner. Recently, we have derivatized SCR7 by introducing spiro ring into core structure. Here, we report the identification of a novel inhibitor of NHEJ, named SCR130 with 20-fold higher efficacy in inducing cytotoxicity in cancer cell lines. SCR130 inhibited DNA end-joining catalyzed by rat tissue extract. Specificity analysis revealed that while SCR130 was specific to Ligase IV, it showed minimal or no effect on Ligase III and Ligase I mediated joining. Importantly, SCR130 exhibited the least cytotoxicity in Ligase IV-null cell line as compared with wild type, confirming Ligase IV-specificity. Furthermore, we demonstrate that SCR130 can potentiate the effect of radiation in cancer cells when used in combination with γ-radiation. Various cellular assays in conjunction with Western blot analysis revealed that treatment with SCR130 led to loss of mitochondrial membrane potential leading to cell death by activating both intrinsic and extrinsic pathways of apoptosis. Thus, we describe a novel inhibitor of NHEJ with higher efficacy and may have the potential to be developed as cancer therapeutic.
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Affiliation(s)
- Ujjayinee Ray
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Sanjay Kumar Raul
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Vindya K Gopinatha
- Department of Studies in Chemistry, ManasaganFindo-frgotri, University of Mysore, Mysuru, India
| | - Dipayan Ghosh
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | | | - Kempegowda Mantelingu
- Department of Studies in Chemistry, ManasaganFindo-frgotri, University of Mysore, Mysuru, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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16
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Importance of Hypericin-Bcl2 interactions for biological effects at subcellular levels. Photodiagnosis Photodyn Ther 2019; 28:38-52. [PMID: 31430575 DOI: 10.1016/j.pdpdt.2019.08.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/18/2019] [Accepted: 08/12/2019] [Indexed: 02/06/2023]
Abstract
Hypericin (Hyp) is a naturally occurring compound used as photosensitizer in photodynamic therapy and diagnosis. Recently, we have shown that Hyp presence alone, without illumination, resulted in substantial biological effects at several sub-cellular levels. Hyp induced changes in cellular ultrastructure, mitochondria function and metabolism, and distribution of Bcl2 proteins in malignant and non-malignant cells. The molecular mechanisms that underlie Hyp light-independent effects are still elusive. We have hypothesized that Bcl2-Hyp interactions might be one possible mechanism. We performed molecular docking studies to determine the Hyp-Bcl2 interaction profile. Based on the interaction profiles small Bcl2 peptide segments were selected for further study. We designed small peptides corresponding to Bcl2 BH3 and BH1 domains and tested the binding of Hyp and Bcl2 known inhibitor, ABT263, to the peptides in computer modeling and in vitro binding studies. We employed endogenous tryptophan and tyrosine in the BH3 and BH1 peptides, respectively, and their fluorescent properties to show interaction with Hyp and ABT263. Overall, our results indicate that Hyp can interact with Bcl2 protein at its BH3-BH1 hydrophobic groove, and this interaction may trigger changes in intracellular distribution of Bcl2 proteins. In addition, our computer modeling results suggest that Hyp also interacts with other anti-apoptotic members of Bcl2 family similar to the known BH3 mimetics. Our findings are novel and might contribute to understanding Hyp light-independent effects. In addition, they may substantiate the therapeutic use of Hyp as a BH3 mimetic molecule to enhance other cancer treatments.
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17
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BCL-2 family isoforms in apoptosis and cancer. Cell Death Dis 2019; 10:177. [PMID: 30792387 PMCID: PMC6384907 DOI: 10.1038/s41419-019-1407-6] [Citation(s) in RCA: 357] [Impact Index Per Article: 71.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 12/17/2018] [Accepted: 01/29/2019] [Indexed: 12/17/2022]
Abstract
The BCl-2 family has long been identified for its role in apoptosis. Following the initial discovery of BCL-2 in the context of B-cell lymphoma in the 1980s, a number of homologous proteins have since been identified. The members of the Bcl-2 family are designated as such due to their BCL-2 homology (BH) domains and involvement in apoptosis regulation. The BH domains facilitate the family members’ interactions with each other and can indicate pro- or anti-apoptotic function. Traditionally, these proteins are categorised into one of the three subfamilies; anti-apoptotic, BH3-only (pro-apoptotic), and pore-forming or ‘executioner’ (pro-apoptotic) proteins. Each of the BH3-only or anti-apoptotic proteins has a distinct pattern of activation, localisation and response to cell death or survival stimuli. All of these can vary across cell or stress types, or developmental stage, and this can cause the delineation of the roles of BCL-2 family members. Added to this complexity is the presence of relatively uncharacterised isoforms of many of the BCL-2 family members. There is a gap in our knowledge regarding the function of BCL-2 family isoforms. BH domain status is not always predictive or indicative of protein function, and several other important sequences, which can contribute to apoptotic activity have been identified. While therapeutic strategies targeting the BCL-2 family are constantly under development, it is imperative that we understand the molecules, which we are attempting to target. This review, discusses our current knowledge of anti-apoptotic BCL-2 family isoforms. With significant improvements in the potential for splicing therapies, it is important that we begin to understand the distinctions of the BCL-2 family, not limited to just the mechanisms of apoptosis control, but in their roles outside of apoptosis.
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18
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Gopalakrishnan V, Dahal S, Radha G, Sharma S, Raghavan SC, Choudhary B. Characterization of DNA double-strand break repair pathways in diffuse large B cell lymphoma. Mol Carcinog 2018; 58:219-233. [DOI: 10.1002/mc.22921] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/18/2018] [Accepted: 10/07/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Vidya Gopalakrishnan
- Institute of Bioinformatics and Applied Biotechnology; Electronics City; Bangalore India
- Manipal Academy of Higher Education; Manipal Karnataka India
| | - Sumedha Dahal
- Department of Biochemistry; Indian Institute of Science; Bangalore India
| | - Gudapureddy Radha
- Department of Biochemistry; Indian Institute of Science; Bangalore India
| | - Shivangi Sharma
- Department of Biochemistry; Indian Institute of Science; Bangalore India
| | | | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology; Electronics City; Bangalore India
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19
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Vartak SV, Swarup HA, Gopalakrishnan V, Gopinatha VK, Ropars V, Nambiar M, John F, Kothanahally SKS, Kumari R, Kumari N, Ray U, Radha G, Dinesh D, Pandey M, Ananda H, Karki SS, Srivastava M, Charbonnier JB, Choudhary B, Mantelingu K, Raghavan SC. Autocyclized and oxidized forms of SCR7 induce cancer cell death by inhibiting nonhomologous DNA end joining in a Ligase IV dependent manner. FEBS J 2018; 285:3959-3976. [PMID: 30230716 DOI: 10.1111/febs.14661] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 08/23/2018] [Accepted: 09/17/2018] [Indexed: 12/17/2022]
Abstract
Nonhomologous DNA end joining (NHEJ) is the major DNA double-strand break (DSB) repair pathway in mammals. Previously, we have described a small molecule inhibitor, SCR7, which can inhibit NHEJ in a Ligase IV-dependent manner. Administration of SCR7 within the cells resulted in the accumulation of DNA breaks, cell death, and inhibition of tumor growth in mice. In the present study, we report that parental SCR7, which is unstable, can be autocyclized into a stable form. Both parental SCR7 and cyclized SCR7 possess the same molecular weight (334.09) and molecular formula (C18 H14 N4 OS), whereas its oxidized form, SCR7-pyrazine, possesses a different molecular formula (C18 H12 N4 OS), molecular weight (332.07), and structure. While cyclized form of SCR7 showed robust inhibition of NHEJ in vitro, both forms exhibited efficient cytotoxicity. Cyclized and oxidized forms of SCR7 inhibited DNA end joining catalyzed by Ligase IV, whereas their impact was minimal on Ligase III, Ligase I, and T4 DNA Ligase-mediated joining. Importantly, both forms inhibited V(D)J recombination, although the effect was more pronounced for SCR7-cyclized. Both forms blocked NHEJ in a Ligase IV-dependent manner leading to the accumulation of DSBs within the cells. Although cytotoxicity due to SCR7-cyclized was Ligase IV specific, the pyrazine form exhibited nonspecific cytotoxicity at higher concentrations in Ligase IV-null cells. Finally, we demonstrate that both forms can potentiate the effect of radiation. Thus, we report that cyclized and oxidized forms of SCR7 can inhibit NHEJ in a Ligase IV-dependent manner, although SCR7-pyrazine is less specific to Ligase IV inside the cell.
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Affiliation(s)
- Supriya V Vartak
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | | | - Vidya Gopalakrishnan
- Institute of Bioinformatics and Applied Biotechnology, Bangalore, India.,Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Vindya K Gopinatha
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Virginie Ropars
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Univ Paris-Saclay, Gif-sur-Yvette Cedex, France
| | - Mridula Nambiar
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Franklin John
- Department of Chemistry, Sacred Heart College, Kochi, India
| | | | - Rupa Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Nitu Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Ujjayinee Ray
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Gudapureddy Radha
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Depina Dinesh
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Monica Pandey
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Hanumappa Ananda
- Department of Biochemistry, Indian Institute of Science, Bangalore, India.,Department of Chemistry, University of Mysore, India
| | - Subhas S Karki
- KLE Academy of Higher Education and Research, KLE College of Pharmacy, Rajajinagar, Bengaluru, India
| | - Mrinal Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Jean Baptiste Charbonnier
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Univ Paris-Saclay, Gif-sur-Yvette Cedex, France
| | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Bangalore, India
| | | | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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20
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Dahal S, Dubey S, Raghavan SC. Homologous recombination-mediated repair of DNA double-strand breaks operates in mammalian mitochondria. Cell Mol Life Sci 2018; 75:1641-1655. [PMID: 29116362 PMCID: PMC11105789 DOI: 10.1007/s00018-017-2702-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 10/23/2017] [Accepted: 10/30/2017] [Indexed: 10/18/2022]
Abstract
Mitochondrial DNA is frequently exposed to oxidative damage, as compared to nuclear DNA. Previously, we have shown that while microhomology-mediated end joining can account for DNA deletions in mitochondria, classical nonhomologous DNA end joining, the predominant double-strand break (DSB) repair pathway in nucleus, is undetectable. In the present study, we investigated the presence of homologous recombination (HR) in mitochondria to maintain its genomic integrity. Biochemical studies revealed that HR-mediated repair of DSBs is more efficient in the mitochondria of testes as compared to that of brain, kidney and spleen. Interestingly, a significant increase in the efficiency of HR was observed when a DSB was introduced. Analyses of the clones suggest that most of the recombinants were generated through reciprocal exchange, while ~ 30% of recombinants were due to gene conversion in testicular extracts. Colocalization and immunoblotting studies showed the presence of RAD51 and MRN complex proteins in the mitochondria and immunodepletion of MRE11, RAD51 or NIBRIN suppressed the HR-mediated repair. Thus, our results reveal importance of homologous recombination in the maintenance of mitochondrial genome stability.
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Affiliation(s)
- Sumedha Dahal
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Shubham Dubey
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India.
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21
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Javadekar SM, Yadav R, Raghavan SC. DNA structural basis for fragility at peak III of BCL2 major breakpoint region associated with t(14;18) translocation. Biochim Biophys Acta Gen Subj 2017; 1862:649-659. [PMID: 29246583 DOI: 10.1016/j.bbagen.2017.12.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/23/2017] [Accepted: 12/07/2017] [Indexed: 12/23/2022]
Abstract
Maintaining genome integrity is crucial for normal cellular functions. DNA double-strand breaks (DSBs), when unrepaired, can potentiate chromosomal translocations. t(14;18) translocation involving BCL2 gene on chromosome 18 and IgH loci at chromosome 14, could lead to follicular lymphoma. Molecular basis for fragility of translocation breakpoint regions is an active area of investigation. Previously, formation of non-B DNA structures like G-quadruplex, triplex, B/A transition were investigated at peak I of BCL2 major breakpoint region (MBR); however, it is less understood at peak III. In vitro gel shift assays show faster mobility for MBR peak III sequences, unlike controls. CD studies of peak III sequences reveal a spectral pattern different from B-DNA. Although complementary C-rich stretches exhibit single-strandedness, corresponding guanine-rich sequences do not show DMS protection, ruling out G-quadruplex and triplex DNA. Extrachromosomal assay indicates that peak III halts transcription, unlike its mutated version. Taken together, multiple lines of evidence suggest formation of potential cruciform DNA structure at MBR peak III, which was also supported by in silico studies. Thus, our study reveals formation of non-B DNA structure which could be a basis for fragility at BCL2 breakpoint regions, eventually leading to chromosomal translocations.
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Affiliation(s)
- Saniya M Javadekar
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Rakhee Yadav
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India.
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22
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Gabellini C, Trisciuoglio D, Del Bufalo D. Non-canonical roles of Bcl-2 and Bcl-xL proteins: relevance of BH4 domain. Carcinogenesis 2017; 38:579-587. [PMID: 28203756 DOI: 10.1093/carcin/bgx016] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 02/14/2017] [Indexed: 02/07/2023] Open
Abstract
Bcl-2 protein family is constituted by multidomain members originally identified as modulators of programmed cell death and whose expression is frequently misbalanced in cancer cells. The lead member Bcl-2 and its homologue Bcl-xL proteins are characterized by the presence of all four conserved BH domain and exert their antiapoptotic role mainly through the involvement of BH1, BH2 and BH3 homology domains, that mediate the interaction with the proapoptotic members of the same Bcl-2 family. The N-terminal BH4 domain of Bcl-2 and Bcl-xL is responsible for the interaction with other proteins that do not belong to Bcl-2 protein family. Beyond a classical role in inhibiting apoptosis, BH4 domain has been characterized as a crucial regulator of other important cellular functions attributed to Bcl-2 and Bcl-xL, including proliferation, autophagy, differentiation, DNA repair, cell migration, tumor progression and angiogenesis. During the last two decades a strong effort has been made to dissect the molecular pathways involved the capability of BH4 domain to regulate the canonical antiapoptotic and the non-canonical activities of Bcl-2 and Bcl-xL, creating the basis for the development of novel anticancer agents targeting this domain. Indeed, recent evidences obtained on in vitro and in vivo model of different cancer histotypes are confirming the promising therapeutic potential of BH4 domain inhibitors supporting their future employment as a novel anticancer strategy.
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Affiliation(s)
- Chiara Gabellini
- Unit of Cell and Developmental Biology, Department of Biology, University of Pisa, 56127 Pisa, Italy
| | - Daniela Trisciuoglio
- Institute of Molecular Biology and Pathology, National Research Council, 00185 Rome, Italy and.,Preclinical Models and New Therapeutic Agents Unit, Regina Elena National Cancer Institute, 00144 Rome, Italy
| | - Donatella Del Bufalo
- Preclinical Models and New Therapeutic Agents Unit, Regina Elena National Cancer Institute, 00144 Rome, Italy
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23
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Srivastava S, Dahal S, Naidu SJ, Anand D, Gopalakrishnan V, Kooloth Valappil R, Raghavan SC. DNA double-strand break repair in Penaeus monodon is predominantly dependent on homologous recombination. DNA Res 2017; 24:117-128. [PMID: 28431013 PMCID: PMC5397610 DOI: 10.1093/dnares/dsw059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 12/08/2016] [Indexed: 11/13/2022] Open
Abstract
DNA double-strand breaks (DSBs) are mostly repaired by nonhomologous end joining (NHEJ) and homologous recombination (HR) in higher eukaryotes. In contrast, HR-mediated DSB repair is the major double-strand break repair pathway in lower order organisms such as bacteria and yeast. Penaeus monodon, commonly known as black tiger shrimp, is one of the economically important crustaceans facing large-scale mortality due to exposure to infectious diseases. The animals can also get exposed to chemical mutagens under the culture conditions as well as in wild. Although DSB repair mechanisms have been described in mammals and some invertebrates, its mechanism is unknown in the shrimp species. In the present study, we show that HR-mediated DSB repair is the predominant mode of repair in P. monodon. Robust repair was observed at a temperature of 30 °C, when 2 µg of cell-free extract derived from hepatopancreas was used for the study. Although HR occurred through both reciprocal recombination and gene conversion, the latter was predominant when the bacterial colonies containing recombinants were evaluated. Unlike mammals, NHEJ-mediated DSB repair was undetectable in P. monodon. However, we could detect evidence for an alternative mode of NHEJ that uses microhomology, termed as microhomology-mediated end joining (MMEJ). Interestingly, unlike HR, MMEJ was predominant at lower temperatures. Therefore, the results suggest that, while HR is major DSB repair pathway in shrimp, MMEJ also plays a role in ensuring the continuity and stability of the genome.
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Affiliation(s)
- Shikha Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Sumedha Dahal
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Sharanya J Naidu
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Deepika Anand
- ICAR-Central Institute of Fisheries Education, Mumbai 400 061, India
| | - Vidya Gopalakrishnan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | | | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
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24
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Ghoshal N, Sharma S, Banerjee A, Kurkalang S, Raghavan SC, Chatterjee A. Influence of reduced glutathione on end-joining of DNA double-strand breaks: Cytogenetical and molecular approach. Mutat Res 2016; 795:1-9. [PMID: 27883910 DOI: 10.1016/j.mrfmmm.2016.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 10/06/2016] [Accepted: 10/22/2016] [Indexed: 10/20/2022]
Abstract
Radiation induced DNA double-strand breaks (DSB) are the major initial lesions whose misrejoining may lead to exchange aberrations. However, the role of glutathione (GSH), a major cellular thiol, in regulating cell's sensitivity to DNA damaging agents is not well understood. Influence of endogenous GSH on the efficiency of X-rays and bleomycin (Blem) induced DNA DSBs end-joining has been tested here cytogenetically, in human lymphocytes and Hct116 cells. In another approach, oligomeric DNA (75bp) containing 5'-compatible and non-compatible overhangs mimicking the endogenous DSB were for rejoining in presence of cell-free extracts from cells having different endogenous GSH levels. Frequency of aberrations, particularly exchange aberrations, was significantly increased when Blem was combined with radiation. The exchange aberration frequency was further enhanced when combined treatment was given at 4°C since DNA lesions are poorly repaired at 4°C so that a higher number of DNA breaks persist and interact when shifted from 4°C to 37°C. The exchange aberrations increased further when the combined treatment was given to Glutathione-ester (GE) pre-treated cells, indicating more frequent rejoining of DNA lesions in presence of higher cellular GSH. This is further supported by the drastic reduction in frequency of exchange aberrations but significant increase in incidences of deletions when combined treatment was given to GSH-depleted cells. End-joining efficiency of DNA DSBs with compatible ends was better than for non-compatible ends. End-joining efficiency of testicular and MCF7 cell extracts was better than that of lungs and Hct116 cells. Cell extract made from GE-treated MCF-7 cells provided more efficient end-joining than from untreated and GSH-depleted cells. However, direct addition of GSH to the cell-free extracts showed considerable reduction in end-joining efficiency. Present data indicate that higher endogenous GSH favours rejoining of DNA DSBs (both restitution and illegitimate reunion) which in turn produce more exchange aberrations.
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Affiliation(s)
- Nitin Ghoshal
- Molecular Genetics Laboratory, Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong, Meghalaya-793022, India
| | - Sheetal Sharma
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Atanu Banerjee
- Molecular Genetics Laboratory, Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong, Meghalaya-793022, India
| | - Sillarine Kurkalang
- Molecular Genetics Laboratory, Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong, Meghalaya-793022, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Anupam Chatterjee
- Molecular Genetics Laboratory, Department of Biotechnology & Bioinformatics, North-Eastern Hill University, Shillong, Meghalaya-793022, India.
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25
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Iyer D, Vartak SV, Mishra A, Goldsmith G, Kumar S, Srivastava M, Hegde M, Gopalakrishnan V, Glenn M, Velusamy M, Choudhary B, Kalakonda N, Karki SS, Surolia A, Raghavan SC. Identification of a novel BCL2-specific inhibitor that binds predominantly to the BH1 domain. FEBS J 2016; 283:3408-37. [DOI: 10.1111/febs.13815] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 07/15/2016] [Accepted: 07/19/2016] [Indexed: 12/19/2022]
Affiliation(s)
- Divyaanka Iyer
- Department of Biochemistry; Indian Institute of Science; Bangalore India
| | - Supriya V. Vartak
- Department of Biochemistry; Indian Institute of Science; Bangalore India
| | - Archita Mishra
- Molecular Biophysics Unit; Indian Institute of Science; Bangalore India
| | - Gunaseelan Goldsmith
- Institute of Bioinformatics and Applied Biotechnology, Electronics City; Bangalore India
| | - Sujeet Kumar
- Department of Pharmaceutical Chemistry; KLE University's College of Pharmacy; Bangalore India
| | - Mrinal Srivastava
- Department of Biochemistry; Indian Institute of Science; Bangalore India
| | - Mahesh Hegde
- Department of Biochemistry; Indian Institute of Science; Bangalore India
| | - Vidya Gopalakrishnan
- Department of Biochemistry; Indian Institute of Science; Bangalore India
- Institute of Bioinformatics and Applied Biotechnology, Electronics City; Bangalore India
| | - Mark Glenn
- Haematology; Department of Molecular and Clinical Cancer Medicine University of Liverpool; UK
| | - Mahesh Velusamy
- Institute of Bioinformatics and Applied Biotechnology, Electronics City; Bangalore India
| | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Electronics City; Bangalore India
| | - Nagesh Kalakonda
- Haematology; Department of Molecular and Clinical Cancer Medicine University of Liverpool; UK
| | - Subhas S. Karki
- Department of Pharmaceutical Chemistry; KLE University's College of Pharmacy; Bangalore India
| | - Avadhesha Surolia
- Molecular Biophysics Unit; Indian Institute of Science; Bangalore India
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26
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Sebastian R, Raghavan SC. Induction of DNA damage and erroneous repair can explain genomic instability caused by endosulfan. Carcinogenesis 2016; 37:929-40. [PMID: 27492056 DOI: 10.1093/carcin/bgw081] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/30/2016] [Indexed: 12/15/2022] Open
Abstract
Endosulfan (ES) is an organochlorine pesticide, speculated to be associated with chromosomal abnormalities and diseases in humans. However, very little is known about the mechanism of its genotoxicity. Using in vivo, ex vivo and in vitro model systems, we show that exposure to ES induces reactive oxygen species (ROS) in a concentration and time-dependent manner. The generation of ROS results in DNA double-strand breaks either directly or in a replication-dependent manner, both in mice and human cells. Importantly, ES-induced DNA damage evokes DNA damage response, resulting in elevated levels of classical non-homologous DNA endjoining (NHEJ), the predominant double-strand break repair pathway in higher eukaryotes. Sequence analyses of NHEJ junctions revealed that ES treatment results in extensive processing of broken DNA, culminating in increased and long junctional deletions, thereby favoring erroneous repair. We also find that exposure to ES leads to significant increase in microhomology-mediated end joining (MMEJ), a LIGASE III-dependent alternative repair pathway. Therefore, we demonstrate that ES induces DNA damage and genomic instability, alters DNA damage response thereby promoting erroneous DNA repair.
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Affiliation(s)
- Robin Sebastian
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
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27
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Pandey M, Kumar S, Goldsmith G, Srivastava M, Elango S, Shameem M, Bannerjee D, Choudhary B, Karki SS, Raghavan SC. Identification and characterization of novel ligase I inhibitors. Mol Carcinog 2016; 56:550-566. [PMID: 27312791 DOI: 10.1002/mc.22516] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 06/06/2016] [Accepted: 06/14/2016] [Indexed: 12/17/2022]
Abstract
The terminal step of ligation of single and/or double-strand breaks during physiological processes such as DNA replication, repair and recombination requires participation of DNA ligases in all mammals. DNA Ligase I has been well characterised to play vital roles during these processes. Considering the indispensable role of DNA Ligase I, a therapeutic strategy to impede proliferation of cancer cells is by using specific small molecule inhibitors against it. In the present study, we have designed and chemically synthesised putative DNA Ligase I inhibitors. Based on various biochemical and biophysical screening approaches, we identify two prospective DNA Ligase I inhibitors, SCR17 and SCR21. Both the inhibitors blocked ligation of nicks on DNA in a concentration-dependent manner, when catalysed by cell-free extracts or purified Ligase I. Docking studies in conjunction with biolayer interferometry and gel shift assays revealed that both SCR17 and SCR21 can bind to Ligase I, particularly to the DNA Binding Domain of Ligase I with KD values in nanomolar range. The inhibitors did not show significant affinity towards DNA Ligase III and DNA Ligase IV. Further, addition of Ligase I could restore the joining, when the inhibitors were treated with testicular cell-free extracts. Ex vivo studies using multiple assays showed that even though cell death was limited in the presence of inhibitors in cancer cells, their proliferation was compromised. Hence, we identify two promising DNA Ligase I inhibitors, which can be used in biochemical and cellular assays, and could be further modified and optimised to target cancer cells. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Monica Pandey
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Sujeet Kumar
- Department of Pharmaceutical Chemistry, KLE University's College of Pharmacy, Bangalore, India
| | - Gunaseelan Goldsmith
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, India
| | - Mrinal Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Santhini Elango
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | | | | | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, India
| | - Subhas S Karki
- Department of Pharmaceutical Chemistry, KLE University's College of Pharmacy, Bangalore, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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28
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Hegde M, Mantelingu K, Swarup HA, Pavankumar CS, Qamar I, Raghavan SC, Rangappa KS. Novel PARP inhibitors sensitize human leukemic cells in an endogenous PARP activity dependent manner. RSC Adv 2016. [DOI: 10.1039/c5ra19150e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Poly(ADP-ribose) polymerase (PARP) is a critical nuclear enzyme which helps in DNA repair. In this study we report, synthesis and biological studies of novel pyridazine derivatives as PARP inhibitors.
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Affiliation(s)
- Mahesh Hegde
- Department of Studies in Chemistry
- Manasagangotri
- University of Mysore
- Mysuru-570006
- India
| | - Kempegowda Mantelingu
- Department of Studies in Chemistry
- Manasagangotri
- University of Mysore
- Mysuru-570006
- India
| | - Hassan A. Swarup
- Department of Studies in Chemistry
- Manasagangotri
- University of Mysore
- Mysuru-570006
- India
| | | | - Imteyaz Qamar
- Department of Biochemistry
- Indian Institute of Science
- Bangalore-560012
- India
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29
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Tadi SK, Sebastian R, Dahal S, Babu RK, Choudhary B, Raghavan SC. Microhomology-mediated end joining is the principal mediator of double-strand break repair during mitochondrial DNA lesions. Mol Biol Cell 2015; 27:223-35. [PMID: 26609070 PMCID: PMC4713127 DOI: 10.1091/mbc.e15-05-0260] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 11/18/2015] [Indexed: 12/13/2022] Open
Abstract
Repair of double-strand breaks in mammalian mitochondria depends on microhomology-mediated end joining (MMEJ). Classical NHEJ is not detectable in mitochondria. DNA ligase III, but not ligase IV or ligase I, is involved in mitochondrial MMEJ. The protein machinery involved in miitochondrial MMEJ includes CtIP, FEN1, ligase III, MRE11, and PARP1. Mitochondrial DNA (mtDNA) deletions are associated with various mitochondrial disorders. The deletions identified in humans are flanked by short, directly repeated mitochondrial DNA sequences; however, the mechanism of such DNA rearrangements has yet to be elucidated. In contrast to nuclear DNA (nDNA), mtDNA is more exposed to oxidative damage, which may result in double-strand breaks (DSBs). Although DSB repair in nDNA is well studied, repair mechanisms in mitochondria are not characterized. In the present study, we investigate the mechanisms of DSB repair in mitochondria using in vitro and ex vivo assays. Whereas classical NHEJ (C-NHEJ) is undetectable, microhomology-mediated alternative NHEJ efficiently repairs DSBs in mitochondria. Of interest, robust microhomology-mediated end joining (MMEJ) was observed with DNA substrates bearing 5-, 8-, 10-, 13-, 16-, 19-, and 22-nt microhomology. Furthermore, MMEJ efficiency was enhanced with an increase in the length of homology. Western blotting, immunoprecipitation, and protein inhibition assays suggest the involvement of CtIP, FEN1, MRE11, and PARP1 in mitochondrial MMEJ. Knockdown studies, in conjunction with other experiments, demonstrated that DNA ligase III, but not ligase IV or ligase I, is primarily responsible for the final sealing of DSBs during mitochondrial MMEJ. These observations highlight the central role of MMEJ in maintenance of mammalian mitochondrial genome integrity and is likely relevant for deletions observed in many human mitochondrial disorders.
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Affiliation(s)
- Satish Kumar Tadi
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Robin Sebastian
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Sumedha Dahal
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Ravi K Babu
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Bangalore 560 100, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
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30
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Sharbeen G, McCarroll J, Goldstein D, Phillips PA. Exploiting base excision repair to improve therapeutic approaches for pancreatic cancer. Front Nutr 2015; 2:10. [PMID: 25988138 PMCID: PMC4428371 DOI: 10.3389/fnut.2015.00010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 03/10/2015] [Indexed: 12/13/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDA) is a highly chemoresistant and metastatic disease with a dismal 5-year survival rate of 6%. More effective therapeutic targets and approaches are urgently needed to tackle this devastating disease. The base excision repair (BER) pathway has been identified as a predictor of therapeutic response, prognostic factor, and therapeutic target in a variety of cancers. This review will discuss our current understanding of BER in PDA and its potential to improve PDA treatment.
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Affiliation(s)
- George Sharbeen
- Pancreatic Cancer Translational Research Group, Lowy Cancer Research Centre, Prince of Wales Clinical School, UNSW Australia , Sydney, NSW , Australia
| | - Joshua McCarroll
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia , Sydney, NSW , Australia
| | - David Goldstein
- Pancreatic Cancer Translational Research Group, Lowy Cancer Research Centre, Prince of Wales Clinical School, UNSW Australia , Sydney, NSW , Australia
| | - Phoebe A Phillips
- Pancreatic Cancer Translational Research Group, Lowy Cancer Research Centre, Prince of Wales Clinical School, UNSW Australia , Sydney, NSW , Australia
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31
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Sharma S, Javadekar SM, Pandey M, Srivastava M, Kumari R, Raghavan SC. Homology and enzymatic requirements of microhomology-dependent alternative end joining. Cell Death Dis 2015; 6:e1697. [PMID: 25789972 PMCID: PMC4385936 DOI: 10.1038/cddis.2015.58] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 12/24/2014] [Accepted: 02/09/2015] [Indexed: 01/19/2023]
Abstract
Nonhomologous DNA end joining (NHEJ) is one of the major double-strand break (DSB) repair pathways in higher eukaryotes. Recently, it has been shown that alternative NHEJ (A-NHEJ) occurs in the absence of classical NHEJ and is implicated in chromosomal translocations leading to cancer. In the present study, we have developed a novel biochemical assay system utilizing DSBs flanked by varying lengths of microhomology to study microhomology-mediated alternative end joining (MMEJ). We show that MMEJ can operate in normal cells, when microhomology is present, irrespective of occurrence of robust classical NHEJ. Length of the microhomology determines the efficiency of MMEJ, 5 nt being obligatory. Using this biochemical approach, we show that products obtained are due to MMEJ, which is dependent on MRE11, NBS1, LIGASE III, XRCC1, FEN1 and PARP1. Thus, we define the enzymatic machinery and microhomology requirements of alternative NHEJ using a well-defined biochemical system.
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Affiliation(s)
- S Sharma
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - S M Javadekar
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - M Pandey
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - M Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - R Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - S C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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32
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Pont LMEB, Naipal K, Kloezeman JJ, Venkatesan S, van den Bent M, van Gent DC, Dirven CMF, Kanaar R, Lamfers MLM, Leenstra S. DNA damage response and anti-apoptotic proteins predict radiosensitization efficacy of HDAC inhibitors SAHA and LBH589 in patient-derived glioblastoma cells. Cancer Lett 2014; 356:525-35. [PMID: 25305451 DOI: 10.1016/j.canlet.2014.09.049] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 09/27/2014] [Accepted: 09/29/2014] [Indexed: 12/15/2022]
Abstract
HDAC inhibitors have radiosensitizing effects in established cancer cell lines. This study was conducted to compare the efficacy of SAHA, LBH589, Valproic Acid (VPA), MS275 and Scriptaid in the patient-derived glioblastoma model. In more detail, SAHA and LBH589 were evaluated to determine predictors of response. Acetylated-histone-H3, γH2AX/53BP1, (p)Chek2/ATM, Bcl-2/Bcl-XL, p21(CIP1/WAF1) and caspase-3/7 were studied in relation to response. SAHA sensitized 50% of cultures, LBH589 45%, VPA and Scriptaid 40% and MS275 60%. Differences after treatment with SAHA/RTx or LBH589/RTx in a sensitive and resistant culture were increased acetylated-H3, caspase-3/7 and prolonged DNA damage repair γH2AX/53BP1 foci. pChek2 was found to be associated with both SAHA/RTx and LBH589/RTx response with a positive predictive value (PPV) of 90%. Bcl-XL had a PPV of 100% for LBH589/RTx response. Incubation with HDACi 24 and 48 hours pre-RTx resulted in the best efficacy of combination treatment. In conclusion a subset of patient-derived glioblastoma cultures were sensitive to HDACi/RTx. For SAHA and LBH589 responses were strongly associated with pChek2 and Bcl-XL, which warrant further clinical exploration. Additional information on responsiveness was obtained by DNA damage response markers and apoptosis related proteins.
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Affiliation(s)
- Lotte M E Berghauser Pont
- Department of Neurosurgery, Brain Tumor Center, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Kishan Naipal
- Department of Genetics, Department Radiation Oncology, Cancer Genomics Netherlands, Erasmus MC Cancer Institute, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Jenneke J Kloezeman
- Department of Neurosurgery, Brain Tumor Center, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Subramanian Venkatesan
- Department of Neurosurgery, Brain Tumor Center, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Martin van den Bent
- Department of Neurology/Neuro-oncology, Brain Tumor Center, Erasmus MC Cancer Institute, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | - Dik C van Gent
- Department of Genetics, Department Radiation Oncology, Cancer Genomics Netherlands, Erasmus MC Cancer Institute, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Clemens M F Dirven
- Department of Neurosurgery, Brain Tumor Center, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Roland Kanaar
- Department of Genetics, Department Radiation Oncology, Cancer Genomics Netherlands, Erasmus MC Cancer Institute, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Martine L M Lamfers
- Department of Neurosurgery, Brain Tumor Center, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Sieger Leenstra
- Department of Neurosurgery, Brain Tumor Center, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands; Department of Neurosurgery, Elizabeth Medical Hospital, Tilburg, The Netherlands.
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33
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Xie C, Edwards H, Caldwell JT, Wang G, Taub JW, Ge Y. Obatoclax potentiates the cytotoxic effect of cytarabine on acute myeloid leukemia cells by enhancing DNA damage. Mol Oncol 2014; 9:409-21. [PMID: 25308513 DOI: 10.1016/j.molonc.2014.09.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 09/09/2014] [Accepted: 09/16/2014] [Indexed: 12/13/2022] Open
Abstract
Resistance to cytarabine and anthracycline-based chemotherapy is a major cause of treatment failure for acute myeloid leukemia (AML) patients. Overexpression of Bcl-2, Bcl-xL, and/or Mcl-1 has been associated with chemoresistance in AML cell lines and with poor clinical outcome of AML patients. Thus, inhibitors of anti-apoptotic Bcl-2 family proteins could be novel therapeutic agents. In this study, we investigated how clinically achievable concentrations of obatoclax, a pan-Bcl-2 inhibitor, potentiate the antileukemic activity of cytarabine in AML cells. MTT assays in AML cell lines and diagnostic blasts, as well as flow cytometry analyses in AML cell lines revealed synergistic antileukemic activity between cytarabine and obatoclax. Bax activation was detected in the combined, but not the individual, drug treatments. This was accompanied by significantly increased loss of mitochondrial membrane potential. Most importantly, in AML cells treated with the combination, enhanced early induction of DNA double-strand breaks (DSBs) preceded a decrease of Mcl-1 levels, nuclear translocation of Bcl-2, Bcl-xL, and Mcl-1, and apoptosis. These results indicate that obatoclax enhances cytarabine-induced apoptosis by enhancing DNA DSBs. This novel mechanism provides compelling evidence for the clinical use of BH3 mimetics in combination with DNA-damaging agents in AML and possibly a broader range of malignancies.
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Affiliation(s)
- Chengzhi Xie
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, USA; Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA; National Engineering Laboratory for AIDS Vaccine, Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, School of Life Sciences, Jilin University, Changchun, PR China
| | - Holly Edwards
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, USA; Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - J Timothy Caldwell
- MD/PhD Program, Wayne State University School of Medicine, Detroit, MI, USA; Cancer Biology Program, Wayne State University School of Medicine, Detroit, MI, USA
| | - Guan Wang
- National Engineering Laboratory for AIDS Vaccine, Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, School of Life Sciences, Jilin University, Changchun, PR China; Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA
| | - Jeffrey W Taub
- Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA; Division of Pediatric Hematology/Oncology, Children's Hospital of Michigan, Detroit, MI, USA; Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA
| | - Yubin Ge
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, USA; Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA; National Engineering Laboratory for AIDS Vaccine, Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, School of Life Sciences, Jilin University, Changchun, PR China.
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34
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Pournazari P, Padmore RF, Kosari F, Scalia P, Shahbani-Rad MT, Shariff S, Demetrick DJ, Bosch M, Mansoor A. B-lymphoblastic leukemia/lymphoma: overexpression of nuclear DNA repair protein PARP-1 correlates with antiapoptotic protein Bcl-2 and complex chromosomal abnormalities. Hum Pathol 2014; 45:1582-7. [DOI: 10.1016/j.humpath.2013.11.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 09/25/2013] [Accepted: 11/22/2013] [Indexed: 01/20/2023]
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35
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Kötter A, Cornils K, Borgmann K, Dahm-Daphi J, Petersen C, Dikomey E, Mansour WY. Inhibition of PARP1-dependent end-joining contributes to Olaparib-mediated radiosensitization in tumor cells. Mol Oncol 2014; 8:1616-25. [PMID: 25028150 DOI: 10.1016/j.molonc.2014.06.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 06/10/2014] [Accepted: 06/11/2014] [Indexed: 12/22/2022] Open
Abstract
Poly-ADP-ribose-polymerase inhibitors (PARPi) are considered to be optimal tools for specifically enhancing radiosensitivity. This effect has been shown to be replication-dependent and more profound in HR-deficient tumors. Here, we present a new mode of PARPi-mediated radiosensitization which was observed in four out of six HR-proficient tumor cell lines (responders) investigated, but not in normal cells. This effect is replication-independent, as the radiosensitization remained unaffected following the inhibition of replication using aphidicolin. We showed that responders are radiosensitized by Olaparib because their DSB-repair is switched to PARP1-dependent end-joining (PARP1-EJ), as evident by (i) the significant increase in the number of residual γH2AX foci following irradiation with 3Gy and treatment with Olaparib, (ii) the enhanced enrichment of PARP1 at the chromatin after 3Gy and (iii) the inhibition of end-joining activity measured by a specific reporter substrate upon Olaparib treatment. This is the first study which directly demonstrates the switch to PARP1-EJ in tumor cells and its contribution to the response to Olaparib as a radiosensitizer, findings which could widen the scope of application of PARPi in tumor therapy.
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Affiliation(s)
- Annika Kötter
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - Kerstin Cornils
- Institute of Bone Marrow Transplantation, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - Kerstin Borgmann
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - Jochen Dahm-Daphi
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - Cordula Petersen
- Department of Radiotherapy & Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - Ekkehard Dikomey
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - Wael Y Mansour
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany; Tumor Biology Department, National Cancer Institute, Cairo University, Egypt.
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36
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G-quadruplex structures formed at the HOX11 breakpoint region contribute to its fragility during t(10;14) translocation in T-cell leukemia. Mol Cell Biol 2013; 33:4266-81. [PMID: 24001773 DOI: 10.1128/mcb.00540-13] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The t(10;14) translocation involving the HOX11 gene is found in several T-cell leukemia patients. Previous efforts to determine the causes of HOX11 fragility were not successful. The role of non-B DNA structures is increasingly becoming an important cause of genomic instability. In the present study, bioinformatics analysis revealed two G-quadruplex-forming motifs at the HOX11 breakpoint cluster. Gel shift assays showed formation of both intra- and intermolecular G-quadruplexes, the latter being more predominant. The structure formation was dependent on four stretches of guanines, as revealed by mutagenesis. Circular dichroism analysis identified parallel conformations for both quadruplexes. The non-B DNA structure could block polymerization during replication on a plasmid, resulting in consistent K(+)-dependent pause sites, which were abolished upon mutation of G-motifs, thereby demonstrating the role of the stretches of guanines even on double-stranded DNA. Extrachromosomal assays showed that the G-quadruplex motifs could block transcription, leading to reduced expression of green fluorescent protein (GFP) within cells. More importantly, sodium bisulfite modification assay showed the single-stranded character at regions I and II of HOX11 in the genome. Thus, our findings suggest the occurrence of G-quadruplex structures at the HOX11 breakpoint region, which could explain its fragility during the t(10;14) translocation.
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37
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Kavitha CV, Nambiar M, Narayanaswamy PB, Thomas E, Rathore U, Ananda Kumar CS, Choudhary B, Rangappa KS, Raghavan SC. Propyl-2-(8-(3,4-difluorobenzyl)-2',5'-dioxo-8-azaspiro[bicyclo[3.2.1] octane-3,4'-imidazolidine]-1'-yl) acetate induces apoptosis in human leukemia cells through mitochondrial pathway following cell cycle arrest. PLoS One 2013; 8:e69103. [PMID: 23922684 PMCID: PMC3724874 DOI: 10.1371/journal.pone.0069103] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/06/2013] [Indexed: 11/19/2022] Open
Abstract
Background Due to the functional defects in apoptosis signaling molecules or deficient activation of apoptosis pathways, leukemia has become an aggressive disease with poor prognosis. Although the majority of leukemia patients initially respond to chemotherapy, relapse is still the leading cause of death. Hence targeting apoptosis pathway would be a promising strategy for the improved treatment of leukemia. Hydantoin derivatives possess a wide range of important biological and pharmacological properties including anticancer properties. Here we investigated the antileukemic activity and mechanism of action of one of the potent azaspiro hydantoin derivative, (ASHD). Materials and Methods To investigate the antileukemic efficacy of ASHD, we have used MTT assay, cell cycle analysis by FACS, tritiated thymidine incorporation assay, Annexin V staining, JC1 staining and western blot analysis. Results Results showed that ASHD was approximately 3-fold more potent than the parent compounds in inducing cytotoxicity. Tritiated thymidine assay in conjunction with cell cycle analysis suggests that ASHD inhibited the growth of leukemic cells. The limited effect of ASHD on cell viability of normal cells indicated that it may be specifically directed to cancer cells. Translocation of phosphatidyl serine, activation of caspase 3, caspase 9, PARP, alteration in the ratio of BCL2/BAD protein expression as well as the loss of mitochondrial membrane potential suggests activation of the intrinsic pathway of apoptosis. Conclusion These results could facilitate the future development of novel hydantoin derivatives as chemotherapeutic agents for leukemia.
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Affiliation(s)
| | - Mridula Nambiar
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | | | - Elizabeth Thomas
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Ujjwal Rathore
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | | | - Bibha Choudhary
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | | | - Sathees C. Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
- * E-mail:
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Srivastava M, Nambiar M, Sharma S, Karki SS, Goldsmith G, Hegde M, Kumar S, Pandey M, Singh RK, Ray P, Natarajan R, Kelkar M, De A, Choudhary B, Raghavan SC. An inhibitor of nonhomologous end-joining abrogates double-strand break repair and impedes cancer progression. Cell 2013; 151:1474-87. [PMID: 23260137 DOI: 10.1016/j.cell.2012.11.054] [Citation(s) in RCA: 279] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 03/07/2012] [Accepted: 11/30/2012] [Indexed: 01/03/2023]
Abstract
DNA Ligase IV is responsible for sealing of double-strand breaks (DSBs) during nonhomologous end-joining (NHEJ). Inhibiting Ligase IV could result in amassing of DSBs, thereby serving as a strategy toward treatment of cancer. Here, we identify a molecule, SCR7 that inhibits joining of DSBs in cell-free repair system. SCR7 blocks Ligase IV-mediated joining by interfering with its DNA binding but not that of T4 DNA Ligase or Ligase I. SCR7 inhibits NHEJ in a Ligase IV-dependent manner within cells, and activates the intrinsic apoptotic pathway. More importantly, SCR7 impedes tumor progression in mouse models and when coadministered with DSB-inducing therapeutic modalities enhances their sensitivity significantly. This inhibitor to target NHEJ offers a strategy toward the treatment of cancer and improvement of existing regimens.
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Affiliation(s)
- Mrinal Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
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A non-B DNA can replace heptamer of V(D)J recombination when present along with a nonamer: implications in chromosomal translocations and cancer. Biochem J 2013; 448:115-25. [PMID: 22891626 DOI: 10.1042/bj20121031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The RAG (recombination-activating gene) complex is responsible for the generation of antigen receptor diversity by acting as a sequence-specific nuclease. Recent studies have shown that it also acts as a structure-specific nuclease. However, little is known about the factors regulating this activity at the genomic level. We show in the present study that the proximity of a V(D)J nonamer to heteroduplex DNA significantly increases RAG cleavage and binding efficiencies at physiological concentrations of MgCl(2). The position of the nonamer with respect to heteroduplex DNA was important, but not orientation. A spacer length of 18 bp between the nonamer and mismatch was optimal for RAG-mediated DNA cleavage. Mutations to the sequence of the nonamer and deletion of the nonamer-binding domain of RAG1 reinforced the role of the nonamer in the enhancement in RAG cleavage. Interestingly, partial mutation of the nonamer did not significantly reduce RAG cleavage on heteroduplex DNA, suggesting that even cryptic nonamers were sufficient to enhance RAG cleavage. More importantly, we show that the fragile region involved in chromosomal translocations associated with BCL2 (B-cell lymphoma 2) can be cleaved by RAGs following a nonamer-dependent mechanism. Hence our results from the present study suggest that a non-B DNA can replace the heptamer of RSS (recombination signal sequence) when present adjacent to nonamers, explaining the generation of certain chromosomal translocations in lymphoid malignancies.
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Somasagara RR, Hegde M, Chiruvella KK, Musini A, Choudhary B, Raghavan SC. Extracts of strawberry fruits induce intrinsic pathway of apoptosis in breast cancer cells and inhibits tumor progression in mice. PLoS One 2012; 7:e47021. [PMID: 23071702 PMCID: PMC3468438 DOI: 10.1371/journal.pone.0047021] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Accepted: 09/07/2012] [Indexed: 01/25/2023] Open
Abstract
Background The consumption of berry fruits, including strawberries, has been suggested to have beneficial effects against oxidative stress mediated diseases. Berries contain multiple phenolic compounds and secondary metabolites that contribute to their biological properties. Methodology/Principal Findings Current study investigates the anticancer activity of the methanolic extract of strawberry (MESB) fruits in leukaemia (CEM) and breast cancer (T47D) cell lines ex vivo, and its cancer therapeutic and chemopreventive potential in mice models. Results of MTT, trypan blue and LDH assays suggested that MESB can induce cytotoxicity in cancer cells, irrespective of origin, in a concentration- and time-dependent manner. Treatment of mice bearing breast adenocarcinoma with MESB blocked the proliferation of tumor cells in a time-dependent manner and resulted in extended life span. Histological and immunohistochemical studies suggest that MESB treatment affected tumor cell proliferation by activating apoptosis and did not result in any side effects. Finally, we show that MESB can induce intrinsic pathway of apoptosis by activating p73 in breast cancer cells, when tumor suppressor gene p53 is mutated. Conclusions/Significance The present study reveals that strawberry fruits possess both cancer preventive and therapeutic values and we discuss the mechanism by which it is achieved.
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Affiliation(s)
| | - Mahesh Hegde
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Kishore K. Chiruvella
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Anjaneyulu Musini
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bangalore, Karnataka, India
| | - Sathees C. Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
- * E-mail:
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The secret life of Bcl-2: Apoptosis-independent inhibition of DNA repair by Bcl-2 family members. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2012; 751:247-257. [DOI: 10.1016/j.mrrev.2012.05.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 05/25/2012] [Accepted: 05/26/2012] [Indexed: 11/22/2022]
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Hegde M, Karki SS, Thomas E, Kumar S, Panjamurthy K, Ranganatha SR, Rangappa KS, Choudhary B, Raghavan SC. Novel levamisole derivative induces extrinsic pathway of apoptosis in cancer cells and inhibits tumor progression in mice. PLoS One 2012; 7:e43632. [PMID: 22970136 PMCID: PMC3438185 DOI: 10.1371/journal.pone.0043632] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 07/23/2012] [Indexed: 11/23/2022] Open
Abstract
Background Levamisole, an imidazo(2,1-b)thiazole derivative, has been reported to be a potential antitumor agent. In the present study, we have investigated the mechanism of action of one of the recently identified analogues, 4a (2-benzyl-6-(4′-fluorophenyl)-5-thiocyanato-imidazo[2,1-b][1], [3], [4]thiadiazole). Materials and Methods ROS production and expression of various apoptotic proteins were measured following 4a treatment in leukemia cell lines. Tumor animal models were used to evaluate the effect of 4a in comparison with Levamisole on progression of breast adenocarcinoma and survival. Immunohistochemistry and western blotting studies were performed to understand the mechanism of 4a action both ex vivo and in vivo. Results We have determined the IC50 value of 4a in many leukemic and breast cancer cell lines and found CEM cells most sensitive (IC50 5 µM). Results showed that 4a treatment leads to the accumulation of ROS. Western blot analysis showed upregulation of pro-apoptotic proteins t-BID and BAX, upon treatment with 4a. Besides, dose-dependent activation of p53 along with FAS, FAS-L, and cleavage of CASPASE-8 suggest that it induces death receptor mediated apoptotic pathway in CEM cells. More importantly, we observed a reduction in tumor growth and significant increase in survival upon oral administration of 4a (20 mg/kg, six doses) in mice. In comparison, 4a was found to be more potent than its parental analogue Levamisole based on both ex vivo and in vivo studies. Further, immunohistochemistry and western blotting studies indicate that 4a treatment led to abrogation of tumor cell proliferation and activation of apoptosis by the extrinsic pathway even in animal models. Conclusion Thus, our results suggest that 4a could be used as a potent chemotherapeutic agent.
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Affiliation(s)
- Mahesh Hegde
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Subhas S. Karki
- Department of Pharmaceutical Chemistry, KLE University's College of Pharmacy, Bangalore, Karnataka, India
| | - Elizabeth Thomas
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Sujeet Kumar
- Department of Pharmaceutical Chemistry, KLE University's College of Pharmacy, Bangalore, Karnataka, India
| | - Kuppusamy Panjamurthy
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | | | | | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bangalore, Karnataka, India
| | - Sathees C. Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
- * E-mail:
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Chiruvella KK, Sebastian R, Sharma S, Karande AA, Choudhary B, Raghavan SC. Time-Dependent Predominance of Nonhomologous DNA End-Joining Pathways during Embryonic Development in Mice. J Mol Biol 2012; 417:197-211. [DOI: 10.1016/j.jmb.2012.01.029] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 01/18/2012] [Accepted: 01/20/2012] [Indexed: 12/26/2022]
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Nambiar M, Raghavan SC. Mechanism of fragility at BCL2 gene minor breakpoint cluster region during t(14;18) chromosomal translocation. J Biol Chem 2012; 287:8688-701. [PMID: 22275374 DOI: 10.1074/jbc.m111.307363] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The t(14;18) translocation in follicular lymphoma is one of the most common chromosomal translocations. Breaks in chromosome 18 are localized at the 3'-UTR of BCL2 gene or downstream and are mainly clustered in either the major breakpoint region or the minor breakpoint cluster region (mcr). The recombination activating gene (RAG) complex induces breaks at IgH locus of chromosome 14, whereas the mechanism of fragility at BCL2 mcr remains unclear. Here, for the first time, we show that RAGs can nick mcr; however, the mechanism is unique. Three independent nicks of equal efficiency are generated, when both Mg(2+) and Mn(2+) are present, unlike a single nick during V(D)J recombination. Further, we demonstrate that RAG binding and nicking at the mcr are independent of nonamer, whereas a CCACCTCT motif plays a critical role in its fragility, as shown by sequential mutagenesis. More importantly, we recapitulate the BCL2 mcr translocation and find that mcr can undergo synapsis with a standard recombination signal sequence within the cells, in a RAG-dependent manner. Further, mutation to the CCACCTCT motif abolishes recombination within the cells, indicating its vital role. Hence, our data suggest a novel, physiologically relevant, nonamer-independent mechanism of RAG nicking at mcr, which may be important for generation of chromosomal translocations in humans.
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Affiliation(s)
- Mridula Nambiar
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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Sharma S, Panjamurthy K, Choudhary B, Srivastava M, Shahabuddin MS, Giri R, Advirao GM, Raghavan SC. A novel DNA intercalator, 8-methoxy pyrimido[4′,5′:4,5]thieno (2,3-b)quinoline-4(3H)-one induces apoptosis in cancer cells, inhibits the tumor progression and enhances lifespan in mice with tumor. Mol Carcinog 2011; 52:413-25. [DOI: 10.1002/mc.21867] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 12/02/2011] [Accepted: 12/06/2011] [Indexed: 11/11/2022]
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Naik AK, Raghavan SC. Differential reaction kinetics, cleavage complex formation, and nonamer binding domain dependence dictate the structure-specific and sequence-specific nuclease activity of RAGs. J Mol Biol 2011; 415:475-88. [PMID: 22119487 DOI: 10.1016/j.jmb.2011.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/27/2011] [Accepted: 11/01/2011] [Indexed: 11/28/2022]
Abstract
During V(D)J recombination, RAG (recombination-activating gene) complex cleaves DNA based on sequence specificity. Besides its physiological function, RAG has been shown to act as a structure-specific nuclease. Recently, we showed that the presence of cytosine within the single-stranded region of heteroduplex DNA is important when RAGs cleave on DNA structures. In the present study, we report that heteroduplex DNA containing a bubble region can be cleaved efficiently when present along with a recombination signal sequence (RSS) in cis or trans configuration. The sequence of the bubble region influences RAG cleavage at RSS when present in cis. We also find that the kinetics of RAG cleavage differs between RSS and bubble, wherein RSS cleavage reaches maximum efficiency faster than bubble cleavage. In addition, unlike RSS, RAG cleavage at bubbles does not lead to cleavage complex formation. Finally, we show that the "nonamer binding region," which regulates RAG cleavage on RSS, is not important during RAG activity in non-B DNA structures. Therefore, in the current study, we identify the possible mechanism by which RAG cleavage is regulated when it acts as a structure-specific nuclease.
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Affiliation(s)
- Abani Kanta Naik
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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Nambiar M, Raghavan SC. How does DNA break during chromosomal translocations? Nucleic Acids Res 2011; 39:5813-25. [PMID: 21498543 PMCID: PMC3152359 DOI: 10.1093/nar/gkr223] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 03/25/2011] [Accepted: 03/29/2011] [Indexed: 12/20/2022] Open
Abstract
Chromosomal translocations are one of the most common types of genetic rearrangements and are molecular signatures for many types of cancers. They are considered as primary causes for cancers, especially lymphoma and leukemia. Although many translocations have been reported in the last four decades, the mechanism by which chromosomes break during a translocation remains largely unknown. In this review, we summarize recent advances made in understanding the molecular mechanism of chromosomal translocations.
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Affiliation(s)
- Mridula Nambiar
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
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