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Mechanism of Human Telomerase Reverse Transcriptase ( hTERT) Regulation and Clinical Impacts in Leukemia. Genes (Basel) 2021; 12:genes12081188. [PMID: 34440361 PMCID: PMC8392866 DOI: 10.3390/genes12081188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/09/2021] [Accepted: 05/17/2021] [Indexed: 01/03/2023] Open
Abstract
The proliferative capacity and continuous survival of cells are highly dependent on telomerase expression and the maintenance of telomere length. For this reason, elevated expression of telomerase has been identified in virtually all cancers, including leukemias; however, it should be noted that expression of telomerase is sometimes observed later in malignant development. This time point of activation is highly dependent on the type of leukemia and its causative factors. Many recent studies in this field have contributed to the elucidation of the mechanisms by which the various forms of leukemias increase telomerase activity. These include the dysregulation of telomerase reverse transcriptase (TERT) at various levels which include transcriptional, post-transcriptional, and post-translational stages. The pathways and biological molecules involved in these processes are also being deciphered with the advent of enabling technologies such as next-generation sequencing (NGS), ribonucleic acid sequencing (RNA-Seq), liquid chromatography-mass spectrometry (LCMS/MS), and many others. It has also been established that TERT possess diagnostic value as most adult cells do not express high levels of telomerase. Indeed, studies have shown that prognosis is not favorable in patients who have leukemias expressing high levels of telomerase. Recent research has indicated that targeting of this gene is able to control the survival of malignant cells and therefore offers a potential treatment for TERT-dependent leukemias. Here we review the mechanisms of hTERT regulation and deliberate their association in malignant states of leukemic cells. Further, we also cover the clinical implications of this gene including its use in diagnostic, prognostic, and therapeutic discoveries.
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Berei J, Eckburg A, Miliavski E, Anderson AD, Miller RJ, Dein J, Giuffre AM, Tang D, Deb S, Racherla KS, Patel M, Vela MS, Puri N. Potential Telomere-Related Pharmacological Targets. Curr Top Med Chem 2020; 20:458-484. [DOI: 10.2174/1568026620666200109114339] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/21/2019] [Accepted: 11/21/2019] [Indexed: 12/22/2022]
Abstract
Telomeres function as protective caps at the terminal portion of chromosomes, containing
non-coding nucleotide sequence repeats. As part of their protective function, telomeres preserve genomic
integrity and minimize chromosomal exposure, thus limiting DNA damage responses. With
continued mitotic divisions in normal cells, telomeres progressively shorten until they reach a threshold
at a point where they activate senescence or cell death pathways. However, the presence of the enzyme
telomerase can provide functional immortality to the cells that have reached or progressed past
senescence. In senescent cells that amass several oncogenic mutations, cancer formation can occur due
to genomic instability and the induction of telomerase activity. Telomerase has been found to be expressed
in over 85% of human tumors and is labeled as a near-universal marker for cancer. Due to this
feature being present in a majority of tumors but absent in most somatic cells, telomerase and telomeres
have become promising targets for the development of new and effective anticancer therapeutics.
In this review, we evaluate novel anticancer targets in development which aim to alter telomerase
or telomere function. Additionally, we analyze the progress that has been made, including preclinical
studies and clinical trials, with therapeutics directed at telomere-related targets. Furthermore, we review
the potential telomere-related therapeutics that are used in combination therapy with more traditional
cancer treatments. Throughout the review, topics related to medicinal chemistry are discussed,
including drug bioavailability and delivery, chemical structure-activity relationships of select therapies,
and the development of a unique telomere assay to analyze compounds affecting telomere elongation.
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Affiliation(s)
- Joseph Berei
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Adam Eckburg
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Edward Miliavski
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Austin D. Anderson
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Rachel J. Miller
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Joshua Dein
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Allison M. Giuffre
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Diana Tang
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Shreya Deb
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Kavya Sri Racherla
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Meet Patel
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Monica Saravana Vela
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Neelu Puri
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
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Structural Features of Nucleoprotein CST/Shelterin Complex Involved in the Telomere Maintenance and Its Association with Disease Mutations. Cells 2020; 9:cells9020359. [PMID: 32033110 PMCID: PMC7072152 DOI: 10.3390/cells9020359] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/23/2020] [Accepted: 01/24/2020] [Indexed: 12/29/2022] Open
Abstract
Telomere comprises the ends of eukaryotic linear chromosomes and is composed of G-rich (TTAGGG) tandem repeats which play an important role in maintaining genome stability, premature aging and onsets of many diseases. Majority of the telomere are replicated by conventional DNA replication, and only the last bit of the lagging strand is synthesized by telomerase (a reverse transcriptase). In addition to replication, telomere maintenance is principally carried out by two key complexes known as shelterin (TRF1, TRF2, TIN2, RAP1, POT1, and TPP1) and CST (CDC13/CTC1, STN1, and TEN1). Shelterin protects the telomere from DNA damage response (DDR) and regulates telomere length by telomerase; while, CST govern the extension of telomere by telomerase and C strand fill-in synthesis. We have investigated both structural and biochemical features of shelterin and CST complexes to get a clear understanding of their importance in the telomere maintenance. Further, we have analyzed ~115 clinically important mutations in both of the complexes. Association of such mutations with specific cellular fault unveils the importance of shelterin and CST complexes in the maintenance of genome stability. A possibility of targeting shelterin and CST by small molecule inhibitors is further investigated towards the therapeutic management of associated diseases. Overall, this review provides a possible direction to understand the mechanisms of telomere borne diseases, and their therapeutic intervention.
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Chen X, Tang WJ, Shi JB, Liu MM, Liu XH. Therapeutic strategies for targeting telomerase in cancer. Med Res Rev 2019; 40:532-585. [PMID: 31361345 DOI: 10.1002/med.21626] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/12/2019] [Accepted: 07/16/2019] [Indexed: 12/13/2022]
Abstract
Telomere and telomerase play important roles in abnormal cell proliferation, metastasis, stem cell maintenance, and immortalization in various cancers. Therefore, designing of drugs targeting telomerase and telomere is of great significance. Over the past two decades, considerable knowledge regarding telomere and telomerase has been accumulated, which provides theoretical support for the design of therapeutic strategies such as telomere elongation. Therefore, the development of telomere-based therapies such as nucleoside analogs, non-nucleoside small molecules, antisense technology, ribozymes, and dominant negative human telomerase reverse transcriptase are being prioritized for eradicating a majority of tumors. While the benefits of telomere-based therapies are obvious, there is a need to address the limitations of various therapeutic strategies to improve the possibility of clinical applications. In this study, current knowledge of telomere and telomerase is discussed, and therapeutic strategies based on recent research are reviewed.
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Affiliation(s)
- Xing Chen
- School of Pharmacy, Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Medical University, Hefei, People's Republic of China
| | - Wen-Jian Tang
- School of Pharmacy, Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Medical University, Hefei, People's Republic of China
| | - Jing Bo Shi
- School of Pharmacy, Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Medical University, Hefei, People's Republic of China
| | - Ming Ming Liu
- School of Pharmacy, Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Medical University, Hefei, People's Republic of China
| | - Xin-Hua Liu
- School of Pharmacy, Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Medical University, Hefei, People's Republic of China
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Quantitative Biology of Human Shelterin and Telomerase: Searching for the Weakest Point. Int J Mol Sci 2019; 20:ijms20133186. [PMID: 31261825 PMCID: PMC6651453 DOI: 10.3390/ijms20133186] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/12/2019] [Accepted: 06/27/2019] [Indexed: 02/06/2023] Open
Abstract
The repetitive telomeric DNA at chromosome ends is protected from unwanted repair by telomere-associated proteins, which form the shelterin complex in mammals. Recent works have provided new insights into the mechanisms of how human shelterin assembles and recruits telomerase to telomeres. Inhibition of telomerase activity and telomerase recruitment to chromosome ends is a promising target for anticancer therapy. Here, we summarize results of quantitative assessments and newly emerged structural information along with the status of the most promising approaches to telomerase inhibition in cancer cells. We focus on the mechanism of shelterin assembly and the mechanisms of how shelterin affects telomerase recruitment to telomeres, addressing the conceptual dilemma of how shelterin allows telomerase action and regulates other essential processes. We evaluate how the identified critical interactions of telomerase and shelterin might be elucidated in future research of new anticancer strategies.
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Assani G, Xiong Y, Zhou F, Zhou Y. Effect of therapies-mediated modulation of telomere and/or telomerase on cancer cells radiosensitivity. Oncotarget 2018; 9:35008-35025. [PMID: 30405890 PMCID: PMC6201854 DOI: 10.18632/oncotarget.26150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/31/2018] [Indexed: 12/11/2022] Open
Abstract
Cancer is one of the leading causes of death in the world. Many strategies of cancer treatment such as radiotherapy which plays a key role in cancer treatment are developed and used nowadays. However, the side effects post-cancer radiotherapy and cancer radioresistance are two major causes of the limitation of cancer radiotherapy effectiveness in the cancer patients. Moreover, reduction of the limitation of cancer radiotherapy effectiveness by reducing the side effects post-cancer radiotherapy and cancer radioresistance is the aim of several radiotherapy-oncologic teams. Otherwise, Telomere and telomerase are two cells components which play an important role in cancer initiation, cancer progression and cancer therapy resistance such as radiotherapy resistance. For resolving the problems of the limitation of cancer radiotherapy effectiveness especially the cancer radio-resistance problems, the radio-gene-therapy strategy which is the use of gene-therapy via modulation of gene expression combined with radiotherapy was developed and used as a new strategy to treat the patients with cancer. In this review, we summarized the information concerning the implication of telomere and telomerase modulation in cancer radiosensitivity.
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Affiliation(s)
- Ganiou Assani
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Tumor Biology Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yudi Xiong
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Tumor Biology Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Fuxiang Zhou
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Tumor Biology Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yunfeng Zhou
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Tumor Biology Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, China
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Schrank Z, Khan N, Osude C, Singh S, Miller RJ, Merrick C, Mabel A, Kuckovic A, Puri N. Oligonucleotides Targeting Telomeres and Telomerase in Cancer. Molecules 2018; 23:molecules23092267. [PMID: 30189661 PMCID: PMC6225148 DOI: 10.3390/molecules23092267] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 08/27/2018] [Accepted: 09/04/2018] [Indexed: 02/07/2023] Open
Abstract
Telomeres and telomerase have become attractive targets for the development of anticancer therapeutics due to their involvement in cancer cell immortality. Currently, several therapeutics have been developed that directly target telomerase and telomeres, such as telomerase inhibitors and G-quadruplex stabilizing ligands. Telomere-specific oligonucleotides that reduce telomerase activity and disrupt telomere architecture are also in development as novel anticancer therapeutics. Specifically, GRN163L and T-oligos have demonstrated promising anticancer activity in multiple cancers types via induction of potent DNA damage responses. Currently, several miRNAs have been implicated in the regulation of telomerase activity and may prove to be valuable targets in the development of novel therapies by reducing expression of telomerase subunits. Targeting miRNAs that are known to increase expression of telomerase subunits may be another strategy to reduce carcinogenesis. This review aims to provide a comprehensive understanding of current oligonucleotide-based anticancer therapies that target telomeres and telomerase. These studies may help design novel therapeutic approaches to overcome the challenges of oligonucleotide therapy in a clinical setting.
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Affiliation(s)
- Zachary Schrank
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA.
| | - Nabiha Khan
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA.
| | - Chike Osude
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA.
| | - Sanjana Singh
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA.
| | - Rachel J Miller
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA.
| | - Collin Merrick
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA.
| | - Alexander Mabel
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA.
| | - Adijan Kuckovic
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA.
| | - Neelu Puri
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA.
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Berardinelli F, Coluzzi E, Sgura A, Antoccia A. Targeting telomerase and telomeres to enhance ionizing radiation effects in in vitro and in vivo cancer models. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2017; 773:204-219. [PMID: 28927529 DOI: 10.1016/j.mrrev.2017.02.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 02/13/2017] [Accepted: 02/14/2017] [Indexed: 01/05/2023]
Abstract
One of the hallmarks of cancer consists in the ability of tumor cells to divide indefinitely, and to maintain stable telomere lengths throughout the activation of specific telomere maintenance mechanisms (TMM). Therefore in the last fifteen years, researchers proposed to target telomerase or telomeric structure in order to block limitless replicative potential of cancer cells providing a fascinating strategy for a broad-spectrum cancer therapy. In the present review, we report in vitro and in vivo evidence regarding the use of chemical agents targeting both telomerase or telomere structure and showing promising antitumor effects when used in combination with ionizing radiation (IR). RNA interference, antisense oligonucleotides (e.g., GRN163L), non-nucleoside inhibitors (e.g., BIBR1532) and nucleoside analogs (e.g., AZT) represent some of the most potent strategies to inhibit telomerase activity used in combination with IR. Furthermore, radiosensitizing effects were demonstrated also for agents acting directly on the telomeric structure such as G4-ligands (e.g., RHPS4 and Telomestatin) or telomeric-oligos (T-oligos). To date, some of these compounds are under clinical evaluation (e.g., GRN163L and KML001). Advantages of Telomere/Telomerase Targeting Compounds (T/TTCs) coupled with radiotherapy may be relevant in the treatment of radioresistant tumors and in the development of new optimized treatment plans with reduced dose adsorbed by patients and consequent attenuation of short- end long-term side effects. Pros and cons of possible future applications in cancer therapy based on the combination of T/TCCs and radiation treatment are discussed.
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Affiliation(s)
- F Berardinelli
- Dipartimento di Scienze, Università Roma Tre, Rome Italy; Istituto Nazionale di Fisica Nucleare, INFN, Sezione di Roma Tre, Rome, Italy.
| | - E Coluzzi
- Dipartimento di Scienze, Università Roma Tre, Rome Italy
| | - A Sgura
- Dipartimento di Scienze, Università Roma Tre, Rome Italy; Istituto Nazionale di Fisica Nucleare, INFN, Sezione di Roma Tre, Rome, Italy
| | - A Antoccia
- Dipartimento di Scienze, Università Roma Tre, Rome Italy; Istituto Nazionale di Fisica Nucleare, INFN, Sezione di Roma Tre, Rome, Italy
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Treating Cancer by Targeting Telomeres and Telomerase. Antioxidants (Basel) 2017; 6:antiox6010015. [PMID: 28218725 PMCID: PMC5384178 DOI: 10.3390/antiox6010015] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/15/2017] [Accepted: 02/16/2017] [Indexed: 12/22/2022] Open
Abstract
Telomerase is expressed in more than 85% of cancer cells. Tumor cells with metastatic potential may have a high telomerase activity, allowing cells to escape from the inhibition of cell proliferation due to shortened telomeres. Human telomerase primarily consists of two main components: hTERT, a catalytic subunit, and hTR, an RNA template whose sequence is complimentary to the telomeric 5′-dTTAGGG-3′ repeat. In humans, telomerase activity is typically restricted to renewing tissues, such as germ cells and stem cells, and is generally absent in normal cells. While hTR is constitutively expressed in most tissue types, hTERT expression levels are low enough that telomere length cannot be maintained, which sets a proliferative lifespan on normal cells. However, in the majority of cancers, telomerase maintains stable telomere length, thereby conferring cell immortality. Levels of hTERT mRNA are directly related to telomerase activity, thereby making it a more suitable therapeutic target than hTR. Recent data suggests that stabilization of telomeric G-quadruplexes may act to indirectly inhibit telomerase action by blocking hTR binding. Telomeric DNA has the propensity to spontaneously form intramolecular G-quadruplexes, four-stranded DNA secondary structures that are stabilized by the stacking of guanine residues in a planar arrangement. The functional roles of telomeric G-quadruplexes are not completely understood, but recent evidence suggests that they can stall the replication fork during DNA synthesis and inhibit telomere replication by preventing telomerase and related proteins from binding to the telomere. Long-term treatment with G-quadruplex stabilizers induces a gradual reduction in the length of the G-rich 3’ end of the telomere without a reduction of the total telomere length, suggesting that telomerase activity is inhibited. However, inhibition of telomerase, either directly or indirectly, has shown only moderate success in cancer patients. Another promising approach of targeting the telomere is the use of guanine-rich oligonucleotides (GROs) homologous to the 3’ telomere overhang sequence (T-oligos). T-oligos, particularly a specific 11-base oligonucleotide (5’-dGTTAGGGTTAG-3’) called T11, have been shown to induce DNA damage responses (DDRs) such as senescence, apoptosis, and cell cycle arrest in numerous cancer cell types with minimal or no cytostatic effects in normal, non-transformed cells. As a result, T-oligos and other GROs are being investigated as prospective anticancer therapeutics. Interestingly, the DDRs induced by T-oligos in cancer cells are similar to the effects seen after progressive telomere degradation in normal cells. The loss of telomeres is an important tumor suppressor mechanism that is commonly absent in transformed malignant cells, and hence, T-oligos have garnered significant interest as a novel strategy to combat cancer. However, little is known about their mechanism of action. In this review, we discuss the current understanding of how T-oligos exert their antiproliferative effects in cancer cells and their role in inhibition of telomerase. We also discuss the current understanding of telomerase in cancer and various therapeutic targets related to the telomeres and telomerase.
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Polettini J, Behnia F, Taylor BD, Saade GR, Taylor RN, Menon R. Telomere Fragment Induced Amnion Cell Senescence: A Contributor to Parturition? PLoS One 2015; 10:e0137188. [PMID: 26397719 PMCID: PMC4580414 DOI: 10.1371/journal.pone.0137188] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/13/2015] [Indexed: 01/08/2023] Open
Abstract
Oxidative stress (OS)-induced senescence of the amniochorion has been associated with parturition at term. We investigated whether telomere fragments shed into the amniotic fluid (AF) correlated with labor status and tested if exogenous telomere fragments (T-oligos) could induce human and murine amnion cell senescence. In a cross-sectional clinical study, AF telomere fragment concentrations quantitated by a validated real-time PCR assay were higher in women in labor at term compared to those not in labor. In vitro treatment of primary human amnion epithelial cells with 40 μM T-oligos ([TTAGGG]2) that mimic telomere fragments, activated p38MAPK, produced senescence-associated (SA) β-gal staining and increased interleukin (IL)-6 and IL-8 production compared to cells treated with complementary DNA sequences (Cont-oligos, [AATCCC]2). T-oligos injected into the uteri of pregnant CD1 mice on day 14 of gestation, led to increased p38MAPK, SA-β-gal (SA β-gal) staining in murine amniotic sacs and higher AF IL-8 levels on day 18, compared to saline treated controls. In summary, term labor AF samples had higher telomere fragments than term not in labor AF. In vitro and in situ telomere fragments increased human and murine amnion p38MAPK, senescence and inflammatory cytokines. We propose that telomere fragments released from senescent fetal cells are indicative of fetal cell aging. Based on our data, these telomere fragments cause oxidative stress associated damages to the term amniotic sac and force them to release other DAMPS, which, in turn, provide a sterile immune response that may be one of the many inflammatory signals required to initiate parturition at term.
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Affiliation(s)
- Jossimara Polettini
- Division of Maternal-Fetal Medicine and Perinatal Research, Department of Obstetrics and Gynecology, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
- Department of Pathology, Botucatu Medical School, UNESP–Univ. Estadual Paulista, Botucatu, Sao Paulo, Brazil
| | - Faranak Behnia
- Division of Maternal-Fetal Medicine and Perinatal Research, Department of Obstetrics and Gynecology, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Brandie D. Taylor
- Department of Epidemiology & Biostatistics, Texas A&M University System Health Science Center, College Station, Texas, United States of America
| | - George R. Saade
- Division of Maternal-Fetal Medicine and Perinatal Research, Department of Obstetrics and Gynecology, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Robert N. Taylor
- Department of Obstetrics and Gynecology, Wake Forest University, Winston Salem, North Carolina, United States of America
| | - Ramkumar Menon
- Division of Maternal-Fetal Medicine and Perinatal Research, Department of Obstetrics and Gynecology, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
- * E-mail:
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11
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Scuotto M, Rivieccio E, Varone A, Corda D, Bucci M, Vellecco V, Cirino G, Virgilio A, Esposito V, Galeone A, Borbone N, Varra M, Mayol L. Site specific replacements of a single loop nucleoside with a dibenzyl linker may switch the activity of TBA from anticoagulant to antiproliferative. Nucleic Acids Res 2015; 43:7702-16. [PMID: 26250112 PMCID: PMC4652776 DOI: 10.1093/nar/gkv789] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 07/23/2015] [Indexed: 12/20/2022] Open
Abstract
Many antiproliferative G-quadruplexes (G4s) arise from the folding of GT-rich strands. Among these, the Thrombin Binding Aptamer (TBA), as a rare example, adopts a monomolecular well-defined G4 structure. Nevertheless, the potential anticancer properties of TBA are severely hampered by its anticoagulant action and, consequently, no related studies have appeared so far in the literature. We wish to report here that suitable chemical modifications in the TBA sequence can preserve its antiproliferative over anticoagulant activity. Particularly, we replaced one residue of the TT or TGT loops with a dibenzyl linker to develop seven new quadruplex-forming TBA based sequences (TBA-bs), which were studied for their structural (CD, CD melting, 1D NMR) and biological (fibrinogen, PT and MTT assays) properties. The three-dimensional structures of the TBA-bs modified at T13 (TBA-bs13) or T12 (TBA-bs12), the former endowed with selective antiproliferative activity, and the latter acting as potently as TBA in both coagulation and MTT assays, were further studied by 2D NMR restrained molecular mechanics. The comparative structural analyses indicated that neither the stability, nor the topology of the G4s, but the different localization of the two benzene rings of the linker was responsible for the loss of the antithrombin activity for TBA-bs13.
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Affiliation(s)
- Maria Scuotto
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Elisa Rivieccio
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Alessia Varone
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Daniela Corda
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Mariarosaria Bucci
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Valentina Vellecco
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Giuseppe Cirino
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Antonella Virgilio
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Veronica Esposito
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Aldo Galeone
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Nicola Borbone
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Michela Varra
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
| | - Luciano Mayol
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, Naples, Italy
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Star-shaped tetraspermine enhances cellular uptake and cytotoxicity of T-oligo in prostate cancer cells. Pharm Res 2014; 32:196-210. [PMID: 25092067 DOI: 10.1007/s11095-014-1455-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Accepted: 07/02/2014] [Indexed: 01/24/2023]
Abstract
PURPOSE An oligonucleotide termed 'T-oligo' having sequence homology with telomere overhang has shown cytotoxicity in multiple cancers. We have demonstrated that T-oligo can induce apoptosis in androgen independent prostate cancer cell line DU-145. In this report, we evaluate the use of star-shaped tetraspermine (SSTS) for delivery of T-oligo. METHODS SSTS was synthesized from spermine and its intrinsic cytotoxicity towards DU-145 cells was compared with spermine and branched polyethyleneimine (bPEI). Atomistic molecular dynamic (MD) simulations were conducted to understand binding and complexation of spermine and SSTS with T-oligo. Complexation was also determined using gel electrophoresis and SYBR gold assay. Complexes were characterized for size, cellular uptake and antiproliferative effect. RESULTS SSTS exhibited significantly lower toxicity than spermine and bPEI. Its affinity towards T-oligo was significantly higher than spermine as determined by experimental studies and confirmed by MD simulations and it formed stable complexes (TONPs) with T-oligo. TONPs facilitated cellular uptake and nuclear accumulation of T-oligo and their cytotoxic potential was observed at concentration several folds lower than that required for T-oligo alone. CONCLUSION SSTS significantly enhanced therapeutic benefits associated with the use of T-oligo and can be developed as a delivery vehicle for its in-vivo therapeutic applications.
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T-oligo as an anticancer agent in colorectal cancer. Biochem Biophys Res Commun 2014; 446:596-601. [PMID: 24632202 DOI: 10.1016/j.bbrc.2014.03.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 03/04/2014] [Indexed: 11/22/2022]
Abstract
In the United States, there will be an estimated 96,830 new cases of colorectal cancer (CRC) and 50,310 deaths in 2014. CRC is often detected at late stages of the disease, at which point there is no effective chemotherapy. Thus, there is an urgent need for effective novel therapies that have minimal effects on normal cells. T-oligo, an oligonucleotide homologous to the 3'-telomere overhang, induces potent DNA damage responses in multiple malignant cell types, however, its efficacy in CRC has not been studied. This is the first investigation demonstrating T-oligo-induced anticancer effects in two CRC cell lines, HT-29 and LoVo, which are highly resistant to conventional chemotherapies. In this investigation, we show that T-oligo may mediate its DNA damage responses through the p53/p73 pathway, thereby inhibiting cellular proliferation and inducing apoptosis or senescence. Additionally, upregulation of downstream DNA damage response proteins, including E2F1, p53 or p73, was observed. In LoVo cells, T-oligo induced senescence, decreased clonogenicity, and increased expression of senescence associated proteins p21, p27, and p53. In addition, downregulation of POT1 and TRF2, two components of the shelterin protein complex which protects telomeric ends, was observed. Moreover, we studied the antiproliferative effects of T-oligo in combination with an EGFR tyrosine kinase inhibitor, Gefitinib, which resulted in an additive inhibitory effect on cellular proliferation. Collectively, these data provide evidence that T-oligo alone, or in combination with other molecularly targeted therapies, has potential as an anti-cancer agent in CRC.
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Dolcetti R, Giunco S, Dal Col J, Celeghin A, Mastorci K, De Rossi A. Epstein-Barr virus and telomerase: from cell immortalization to therapy. Infect Agent Cancer 2014; 9:8. [PMID: 24572088 PMCID: PMC3943417 DOI: 10.1186/1750-9378-9-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 02/24/2014] [Indexed: 12/18/2022] Open
Abstract
Overcoming cellular senescence is strictly required for virus-driven tumors, including those associated with Epstein-Barr virus (EBV). This critical step is successfully accomplished by EBV through TERT expression and telomerase activation in infected cells. We herein review the complex interplay between EBV and TERT/telomerase in EBV-driven tumorigenesis. Evidence accumulated so far clearly indicates that elucidation of this issue may offer promising opportunities for the design of innovative treatment modalities for EBV-associated malignancies. Indeed, several therapeutic strategies for telomerase inhibition have been developed and are being investigated in clinical trials. In this respect, our recent finding that TERT inhibition sensitizes EBV+ lymphoma cells to antivirals through activation of EBV lytic replication is particularly promising and provides a rationale for the activation of clinical studies aimed at assessing the effects of combination therapies with TERT inhibitors and antivirals for the treatment of EBV-associated malignancies.
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Affiliation(s)
- Riccardo Dolcetti
- Cancer Bio-Immunotherapy Unit, CRO Aviano, National Cancer Institute, Aviano, PN, Italy.
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15
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Haery L, Lugo-Picó JG, Henry RA, Andrews AJ, Gilmore TD. Histone acetyltransferase-deficient p300 mutants in diffuse large B cell lymphoma have altered transcriptional regulatory activities and are required for optimal cell growth. Mol Cancer 2014; 13:29. [PMID: 24529102 PMCID: PMC3930761 DOI: 10.1186/1476-4598-13-29] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 02/05/2014] [Indexed: 11/10/2022] Open
Abstract
Background Recent genome-wide studies have shown that approximately 30% of diffuse large B-cell lymphoma (DLBCL) cases harbor mutations in the histone acetyltransferase (HAT) coactivators p300 or CBP. The majority of these mutations reduce or eliminate the catalytic HAT activity. We previously demonstrated that the human DLBCL cell line RC-K8 expresses a C-terminally truncated, HAT-defective p300 protein (p300ΔC-1087), whose expression is essential for cell proliferation. Methods Using results from large-scale DLBCL studies, we have identified and characterized a second C-terminally truncated, HAT-defective p300 mutant, p300ΔC-820, expressed in the SUDHL2 DLBCL cell line. Properties of p300ΔC-820 were characterized in the SUDHL2 DLBCL cell line by Western blotting, co-immunoprecipitation, and shRNA gene knockdown, as well by using cDNA expression vectors for p300ΔC-820 in pull-down assays, transcriptional reporter assays, and immunofluorescence experiments. A mass spectrometry-based method was used to compare the histone acetylation profile of DLBCL cell lines expressing various levels of wild-type p300. Results We show that the SUDHL2 cell line expresses a C-terminally truncated, HAT-defective form of p300 (p300ΔC-820), but no wild-type p300. The p300ΔC-820 protein has a wild-type ability to localize to subnuclear “speckles,” but has a reduced ability to enhance transactivation by transcription factor REL. Knockdown of p300ΔC-820 in SUDHL2 cells reduced their proliferation and soft agar colony-forming ability. In RC-K8 cells, knockdown of p300ΔC-1087 resulted in increased expression of mRNA and protein for REL target genes A20 and IκBα, two genes that have been shown to limit the growth of RC-K8 cells when overexpressed. Among a panel of B-lymphoma cell lines, low-level expression of full-length p300 protein, which is characteristic of the SUDHL2 and RC-K8 cells, was associated with decreased acetylation of histone H3 at lysines 14 and 18. Conclusions The high prevalence of p300 mutations in DLBCL suggests that HAT-deficient p300 activity defines a subtype of DLBCL, which we have investigated using human DLBCL cell lines RC-K8 and SUDHL2. Our results suggest that truncated p300 proteins contribute to DLBCL cell growth by affecting the expression of specific genes, perhaps through a mechanism that involves alterations in global histone acetylation.
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Affiliation(s)
| | | | | | | | - Thomas D Gilmore
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA.
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16
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Pitman RT, Wojdyla L, Puri N. Mechanism of DNA damage responses induced by exposure to an oligonucleotide homologous to the telomere overhang in melanoma. Oncotarget 2014; 4:761-71. [PMID: 23800953 PMCID: PMC3742836 DOI: 10.18632/oncotarget.1047] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
T-oligo, an 11-base oligonucleotide homologous to the 3'-telomeric overhang, is a novel, potent therapeutic modality in melanoma and multiple other tumor types. T-oligo is proposed to function in a manner similar to experimental disruption of the telomere overhang and induces DNA damage responses including apoptosis, differentiation and senescence. However, important components involved in T-oligo induced responses are not defined, particularly the role of p53, TRF1 and TRF2 in mediating the T-oligo induced responses. In MU, PM-WK, and MM-MC melanoma cells, exposure to T-oligo upregulates p53 expression and phosphorylation, resulting in cellular differentiation and activation of a caspase-mediated apoptotic cascade. However, siRNA-mediated knockdown of p53 completely blocks T-oligo induced differentiation and significantly decreases apoptosis, suggesting that p53 is an important mediator of T-oligo induced responses. In addition, we characterized the roles of telomere binding proteins, TRF1, TRF2, and tankyrase-1, in T-oligo induced damage responses. We demonstrate that tankyrase-1 activity is required for initiation of T-oligo induced damage responses including p53 phosphorylation and reduction of cellular proliferation. These results highlight TRF1, TRF2, tankyrase-1 and p53 as important elements in T-oligo mediated responses and suggest new avenues for research into T-oligo's mechanism of action.
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Affiliation(s)
- Ryan T Pitman
- Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford, Illinois, USA
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17
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Mulnix RE, Pitman RT, Retzer A, Bertram C, Arasi K, Crees Z, Girard J, Uppada SB, Stone AL, Puri N. hnRNP C1/C2 and Pur-beta proteins mediate induction of senescence by oligonucleotides homologous to the telomere overhang. Onco Targets Ther 2013; 7:23-32. [PMID: 24379680 PMCID: PMC3872271 DOI: 10.2147/ott.s54575] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Background Experimental disruption of the telomere overhang induces a potent DNA damage response and is the target of newly emerging cancer therapeutics. Introduction of T-oligo, an eleven-base oligonucleotide homologous to the 3′-telomeric overhang, mimics telomere disruption and induces DNA damage responses through activation of p53, p73, p95/Nbs1, E2F1, pRb, and other DNA damage response proteins. ATM (ataxia telangiectasia mutated) was once thought to be the primary driver of T-oligo-induced DNA damage responses; however, recent experiments have highlighted other key proteins that may also play a significant role. Methods To identify proteins associated with T-oligo, MM-AN cells were treated with biotinylated T-oligo or complementary oligonucleotide, cell lysates were run on SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis), and the protein bands observed after treatment of cells with T-oligo or complementary oligonucleotide were analyzed using mass spectrometry. To study the effect of T-oligo on expression of hnRNP C1/C2 (heterogeneous nuclear ribonucleoprotein C1 and C2) and purine-rich element binding proteins (Pur proteins), cells were treated with T-oligo, and immunoblotting experiments were performed. To determine their role in senescence, cells were treated with shRNA (short hairpin ribonucleic acid) against these proteins, and senescence was studied using the senescence associated beta-galactosidase assay. Results Using mass spectrometry, RNA-binding hnRNP C1/C2 and DNA-binding Pur proteins were found to associate with T-oligo. hnRNP C1/C2 exhibited increased expression (3.6–12.0-fold) in non-small-cell lung cancer (NSCLC) and in melanoma cells (4.5–5.2-fold), and Pur proteins exhibited increased expression of 2.2-fold in NSCLC and 2.0-fold in melanoma cells after T-oligo treatment. Experimental knockdown of hnRNP C1/C2 and Pur-beta completely abrogated T-oligo induced senescence in both MU melanoma and H358 NSCLC cells. Additionally, knockdown of Pur-beta prevented T-oligo-induced phosphorylation of p53, hypophosphorylation of pRb, and upregulation of E2F1, p21, and p53. Conclusion These novel findings highlight proteins essential to T-oligo’s anticancer effects that may be of interest in telomere biology and cancer therapeutics.
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Affiliation(s)
- Richard E Mulnix
- Department of Biomedical Sciences, University of Illinois at Chicago, Rockford, IL, USA
| | - Ryan T Pitman
- Department of Biomedical Sciences, University of Illinois at Chicago, Rockford, IL, USA
| | - Allison Retzer
- College of Medicine, University of Illinois at Chicago, Rockford, IL, USA
| | - Ceyda Bertram
- Department of Biomedical Sciences, University of Illinois at Chicago, Rockford, IL, USA
| | - Kavin Arasi
- College of Medicine, University of Illinois at Chicago, Rockford, IL, USA
| | - Zachary Crees
- College of Medicine, University of Illinois at Chicago, Rockford, IL, USA
| | - Jennifer Girard
- College of Medicine, University of Illinois at Chicago, Rockford, IL, USA
| | | | - Amanda L Stone
- Department of Biomedical Sciences, University of Illinois at Chicago, Rockford, IL, USA
| | - Neelu Puri
- Department of Biomedical Sciences, University of Illinois at Chicago, Rockford, IL, USA
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18
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Fadri-Moskwik M, Zhou Q, Chai W. Beyond Telomerase: Telomere Instability as a Novel Target for Cancer Therapy. J Mol Genet Med 2013; 7. [PMID: 27123041 PMCID: PMC4844356 DOI: 10.4172/1747-0862.1000091] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Telomeres are areas of heterochromatin composed of TTAGGG repeats located at the ends of linear chromosomes. They play a critical role in keeping genome stable and preventing premature aging diseases and the development of cancer. Characterizing mechanisms of telomere maintenance and understanding how their deregulation contributes to human diseases are therefore important for developing novel therapies. A key mechanism driving telomere maintenance and replicative immortality in cancer cells is telomere elongation by telomerase, and many emerging potential telomere-based therapies have focused on targeting telomerase components. By contrast, recent studies on telomere maintenance mechanism suggest that disrupting telomere stability by interfering with alternative mechanisms of telomere synthesis or protection may also yield new strategies for the treatment of cancer. This review will focus on emerging regulators of telomere synthesis or maintenance, such as G4 telomeric DNA, the CST complex, the t-loop, and shelterins, and discuss their potential as targets for anti-cancer chemotherapeutic intervention in the future.
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Affiliation(s)
- Maria Fadri-Moskwik
- Section of Medical Sciences and School of Molecular Biosciences, Washington State University, USA
| | - Qing Zhou
- Section of Medical Sciences and School of Molecular Biosciences, Washington State University, USA
| | - Weihang Chai
- Section of Medical Sciences and School of Molecular Biosciences, Washington State University, USA
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19
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Puri N, Pitman RT, Mulnix RE, Erickson T, Iness AN, Vitali C, Zhao Y, Salgia R. Non-small cell lung cancer is susceptible to induction of DNA damage responses and inhibition of angiogenesis by telomere overhang oligonucleotides. Cancer Lett 2013; 343:14-23. [PMID: 24041868 DOI: 10.1016/j.canlet.2013.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 08/15/2013] [Accepted: 09/08/2013] [Indexed: 10/26/2022]
Abstract
Exposure of the telomere overhang acts as a DNA damage signal, and exogenous administration of an 11-base oligonucleotide homologous to the 3'-telomere overhang sequence (T-oligo) mimics the effects of overhang exposure by inducing senescence and cell death in non-small cell lung cancer (NSCLC) cells, but not in normal bronchial epithelial cells. T-oligo-induced decrease in cellular proliferation in NSCLC is likely directed through both p53 and its homolog, p73, with subsequent induction of senescence and expression of senescence-associated proteins, p21, p33(ING), and p27(Kip1) both in vivo and in vitro. Additionally, T-oligo decreases tumor size and inhibits angiogenesis through decreased VEGF signaling and increased TSP-1 expression.
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Affiliation(s)
- Neelu Puri
- Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford, IL, United States.
| | - Ryan T Pitman
- Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford, IL, United States
| | - Richard E Mulnix
- Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford, IL, United States
| | - Terrianne Erickson
- Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford, IL, United States
| | - Audra N Iness
- Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford, IL, United States
| | - Connie Vitali
- Department of Pathology, University of Illinois College of Medicine, Rockford, IL, United States
| | - Yutong Zhao
- Department of Medicine, Division of Pulmonary, Allergy, Critical Care, University of Pittsburgh, Pittsburgh, PA, United States
| | - Ravi Salgia
- Department of Medicine, Section of Hematology/Oncology, University of Chicago, Chicago, IL, United States
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20
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Roh JI, Sung YH, Lee HW. Clinical implications of antitelomeric drugs with respect to the nontelomeric functions of telomerase in cancer. Onco Targets Ther 2013; 6:1161-6. [PMID: 24009427 PMCID: PMC3762763 DOI: 10.2147/ott.s50918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Telomerase is responsible for maintaining the length of telomeres at the ends of chromosomes. Although most somatic cells do not exhibit telomerase activity, it is reactivated in approximately 85% of cancers. This simple and attractive phenomenon steers the development of anticancer drugs targeting telomeres and telomerase. Recent studies have been revealing extratelomeric roles of telomerase in normal tissues, affecting processes that are critical for survival and aging of organisms. In this review, we will discuss the current therapeutic strategies targeting telomeres and telomerase and evaluate their potential advantages and risks with respect to nontelomeric functions.
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Affiliation(s)
- Jae-Il Roh
- Mouse Molecular Genetics Laboratory, Department of Biochemistry, Yonsei Laboratory Animal Research Center, Yonsei University, Seoul, Korea
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21
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Rankin AM, Forman L, Sarkar S, Faller DV. Enhanced cytotoxicity from deoxyguanosine-enriched T-oligo in prostate cancer cells. Nucleic Acid Ther 2013; 23:311-21. [PMID: 23971906 DOI: 10.1089/nat.2013.0420] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Prostate cancer represents approximately 10 percent of all cancer cases in men and accounts for more than a quarter of all cancer types. Advances in understanding the molecular mechanisms of prostate cancer progression, however, have not translated well to the clinic. Patients with metastatic and hormone-refractory disease have only palliative options for treatment, as chemotherapy seldom produces durable or complete responses, highlighting the need for novel therapeutic approaches. T-oligo, a single-stranded deoxyribonucleic acid with partial sequence homology to human telomeric DNA, has elicited cytostatic and/or cytotoxic effects in multiple cancer cell types. In contrast, normal primary cells of varying tissue types are resistant to cytotoxic actions of T-oligo, underscoring its potential utility as a novel targeted cancer therapeutic. Mechanistically, T-oligo is hypothesized to interfere with normal telomeric structure and form G-quadruplex structures, thereby inducing genomic stress in addition to aberrant upregulation of DNA damageresponse pathways. Here, we present data demonstrating the enhanced effectiveness of a deoxyguanosine-enriched sequence of T-oligo, termed (GGTT)4, which elicits robust cytotoxic effects in prostate cancer cells at lower concentrations than the most recent T-oligo sequence (5'-pGGT TAG GTG TAG GTT T 3') described to date and used for comparison in this study, while exerting no cytotoxic actions on nontransformed human prostate epithelial cells. Additionally, we provide evidence supporting the T-oligo induced activation of cJun N-terminal kinase (JNK) signaling in prostate cancer cells consistent with G-quadruplex formation, thereby significantly advancing the understanding of the T-oligo mechanism of action.
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Affiliation(s)
- Andrew M Rankin
- Cancer Center and Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
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22
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Thompson RC, Vardinogiannis I, Gilmore TD. The sensitivity of diffuse large B-cell lymphoma cell lines to histone deacetylase inhibitor-induced apoptosis is modulated by BCL-2 family protein activity. PLoS One 2013; 8:e62822. [PMID: 23667527 PMCID: PMC3647059 DOI: 10.1371/journal.pone.0062822] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Accepted: 03/26/2013] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Diffuse large B-cell lymphoma (DLBCL) is a genetically heterogeneous disease and this variation can often be used to explain the response of individual patients to chemotherapy. One cancer therapeutic approach currently in clinical trials uses histone deacetylase inhibitors (HDACi's) as monotherapy or in combination with other agents. METHODOLOGY/PRINCIPAL FINDINGS We have used a variety of cell-based and molecular/biochemical assays to show that two pan-HDAC inhibitors, trichostatin A and vorinostat, induce apoptosis in seven of eight human DLBCL cell lines. Consistent with previous reports implicating the BCL-2 family in regulating HDACi-induced apoptosis, ectopic over-expression of anti-apoptotic proteins BCL-2 and BCL-XL or pro-apoptotic protein BIM in these cell lines conferred further resistance or sensitivity, respectively, to HDACi treatment. Additionally, BCL-2 family antgonist ABT-737 increased the sensitivity of several DLBCL cell lines to vorinostat-induced apoptosis, including one cell line (SUDHL6) that is resistant to vorinostat alone. Moreover, two variants of the HDACi-sensitive SUDHL4 cell line that have decreased sensitivity to vorinostat showed up-regulation of BCL-2 family anti-apoptotic proteins such as BCL-XL and MCL-1, as well as decreased sensitivity to ABT-737. These results suggest that the regulation and overall balance of anti- to pro-apoptotic BCL-2 family protein expression is important in defining the sensitivity of DLBCL to HDACi-induced apoptosis. However, the sensitivity of DLBCL cell lines to HDACi treatment does not correlate with expression of any individual BCL-2 family member. CONCLUSIONS/SIGNIFICANCE These studies indicate that the sensitivity of DLBCL to treatment with HDACi's is dependent on the complex regulation of BCL-2 family members and that BCL-2 antagonists may enhance the response of a subset of DLBCL patients to HDACi treatment.
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Affiliation(s)
- Ryan C. Thompson
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Iosif Vardinogiannis
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Thomas D. Gilmore
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
- * E-mail:
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Sarkar S, Faller DV. Telomere-homologous G-rich oligonucleotides sensitize human ovarian cancer cells to TRAIL-induced growth inhibition and apoptosis. Nucleic Acid Ther 2013; 23:167-74. [PMID: 23634944 DOI: 10.1089/nat.2012.0401] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
G-rich T-oligos (GT-oligos; oligonucleotides with homology to telomeres) elicit a DNA damage response in cells and induce cytotoxic effects in certain tumor cell lines. We have previously shown that GT-oligo inhibits growth, arrests cell cycle, and induces apoptosis in ovarian, pancreatic, and prostate cancer cells. However, not all ovarian cancer cell lines are susceptible to GT-oligo exposure. GT-oligo was found to induce transcript expression of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors DR-4 and DR-5, which are generally silenced in ovarian cancer cells, rendering them insensitive to TRAIL. Exposure of TRAIL- and GT-oligo-resistant cell lines to GT-oligo rendered them sensitive to the cytotoxic effects of TRAIL, producing more than additive inhibition of growth. An intracellular inhibitor of the extrinsic apoptotic pathway, FLICE-like Inhibitory Protein-Short (FLIPs), was down-regulated and Jun kinase (JNK) was activated by exposure to GT-oligo. JNK inhibition partially reversed the growth inhibition caused by the combination of GT-oligo and TRAIL indicating partial involvement of the Jun kinase pathway in the resulting cytotoxic effect. Both capase-8 and caspases 3/7 were activated by exposure to GT-oligo plus TRAIL, consistent with activation of the extrinsic apoptotic pathway. These results demonstrate a novel way of sensitizing resistant ovarian cancer cells to TRAIL-mediated cytotoxicity.
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Affiliation(s)
- Sibaji Sarkar
- Cancer Center, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Takahashi R, Sato T, Klinman DM, Shimosato T, Kaneko T, Ishigatsubo Y. Suppressive oligodeoxynucleotides synergistically enhance antiproliferative effects of anticancer drugs in A549 human lung cancer cells. Int J Oncol 2012; 42:429-36. [PMID: 23291718 PMCID: PMC3583819 DOI: 10.3892/ijo.2012.1755] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Accepted: 12/04/2012] [Indexed: 12/11/2022] Open
Abstract
Immunosuppressive oligodeoxynucleotides (Sup ODNs) containing repetitive TTAGGG motifs reduce inflammation and, thus, may have an impact on inflammation-related tumor growth. In this study, we found a significant antiproliferative effect of Sup ODNs on the A549 non-small cell lung cancer (NSCLC) cell line compared to those treated with control ODNs (p<0.05). Sup-ODN-mediated G1 phase cell cycle arrest was achieved via inhibition of Akt and extra-cellular signal-regulated kinase 1/2 phosphorylation and the p15INK4b and p27KIP1/retinoblastoma protein pathway. In addition, Sup ODNs induced apoptosis and enhanced apoptosis when combined with vinorelbine. In a setting similar to clinical use of multidrug chemotherapy for advanced NSCLC, these effects were investigated by using Sup ODNs in combination with conventional anticancer drugs. Sup ODNs had a significant synergistic effect with 5-fluorouracil, vinorelbine, gemcitabine, paclitaxel and irinotecan, with a mean combination index of 0.43–0.78 (<1.0 indicates synergism) in the A549 NSCLC cell line. In conclusion, our results showed that Sup ODNs have an anticancer effect and increase the sensitivity of NSCLC cells to conventional anticancer drugs by modifying Akt and the extra-cellular signal-regulated kinase 1/2 pathway. Thus, Sup ODNs may serve as a novel therapeutic strategy for NSCLC patients.
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Affiliation(s)
- Ryohei Takahashi
- Department of Internal Medicine and Clinical Immunology, Yokohama City University Graduate School of Medicine, Yokohama 236‑0004, Japan
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Dahmen V, Kriehuber R. Cytotoxic effects and specific gene expression alterations induced by I-125-labeled triplex-forming oligonucleotides. Int J Radiat Biol 2012; 88:972-9. [PMID: 22694342 PMCID: PMC3518296 DOI: 10.3109/09553002.2012.702298] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE Triplex-forming oligonucleotides (TFO) bind to the DNA double helix in a sequence-specific manner. Therefore, TFO seem to be a suitable carrier for Auger electron emitters to damage exclusively targeted DNA sequences, e.g., in tumor cells. We studied the influence of I-125 labeled TFO with regard to cell survival and induction of DNA double-strand breaks (DSB) using TFO with different genomic targets and target numbers. Furthermore, the ability of TFO to alter the gene expression of targeted genes was examined. MATERIALS AND METHODS TFO were labeled with I-125 using the primer extension method. DNA triplex formation and sequence-specific DSB were demonstrated in vitro. Cell survival was analyzed by colony-forming assay and DNA damage was assessed by microscopic quantification of protein 53 binding protein 1 (53BP1) foci in the human squamous carcinoma cell line II (SCL-II). Quantitative real-time polymerase-chain-reaction (qRT-PCR) was performed to analyze gene expression alterations. RESULTS The sequence-specific induction of a single DSB in a 1695 bp long DNA double stranded fragment was demonstrated in vitro. I-125-labeled TFO binding to single and multiple targets were shown to induce a pronounced decrease in cell survival and an increase of DSB. TFO targeting multiple sites differing in the total target number showed a significant different cell killing per decay that is also in good accordance with the observed induction of DSB. Single gene targeting I-125-labeled TFO significantly decreased cell survival and altered gene expression in the targeted gene. CONCLUSIONS I-125-labeled TFO enable specific targeting of DNA in vitro as well as in a cellular environment and thus induce sequence-specific complex DNA lesions. Therefore I-125-labeled TFO might be a very useful tool for basic DNA repair research.
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Affiliation(s)
- Volker Dahmen
- Radiation Biology Unit, Department of Safety and Radiation Protection, Forschungszentrum Jülich GmbH, Jülich, Germany
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Ruden M, Puri N. Novel anticancer therapeutics targeting telomerase. Cancer Treat Rev 2012; 39:444-56. [PMID: 22841437 DOI: 10.1016/j.ctrv.2012.06.007] [Citation(s) in RCA: 222] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 06/14/2012] [Accepted: 06/19/2012] [Indexed: 12/12/2022]
Abstract
Telomeres are protective caps at the ends of human chromosomes. Telomeres shorten with each successive cell division in normal human cells whereas, in tumors, they are continuously elongated by human telomerase reverse transcriptase (hTERT). Telomerase is overexpressed in 80-95% of cancers and is present in very low levels or is almost undetectable in normal cells. Because telomerase plays a pivotal role in cancer cell growth it may serve as an ideal target for anticancer therapeutics. Inhibition of telomerase may lead to a decrease of telomere length resulting in cell senescence and apoptosis in telomerase positive tumors. Several strategies of telomerase inhibition are reviewed, including small molecule inhibitors, antisense oligonucleotides, immunotherapies and gene therapies, targeting the hTERT or the ribonucleoprotein subunit hTER. G-quadruplex stabilizers, tankyrase and HSP90 inhibitors targeting telomere and telomerase assembly, and T-oligo approach are also covered. Based on this review, the most promising current telomerase targeting therapeutics are the antisense oligonucleotide inhibitor GRN163L and immunotherapies that use dendritic cells (GRVAC1), hTERT peptide (GV1001) or cryptic peptides (Vx-001). Most of these agents have entered phase I and II clinical trials in patients with various tumors, and have shown good response rates as evidenced by a reduction in tumor cell growth, increased overall disease survival, disease stabilization in advanced staged tumors and complete/partial responses. Most therapeutics have shown to be more effective when used in combination with standard therapies, resulting in concomitant telomere shortening and tumor mass shrinkage, as well as preventing tumor relapse and resistance to single agent therapy.
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Affiliation(s)
- Maria Ruden
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107-1822, USA
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Alternative strategy for Alzheimer's disease: stress response triggers. Int J Alzheimers Dis 2012; 2012:684283. [PMID: 22655213 PMCID: PMC3357936 DOI: 10.1155/2012/684283] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 02/22/2012] [Indexed: 11/25/2022] Open
Abstract
Stress resistance capacity is a hallmark of longevity protection and survival throughout the plant and animal kingdoms. Latent pathway activation of protective cascades, triggered by environmental challenges to tolerate heat, oxygen deprivation, reactive oxygen species (ROS), diet restriction, and exercise provides tolerance to these stresses. Age-related changes and disease vulnerability mark an increase in damage, like damage induced by environmental challenges. An alternative approach to immunotherapy intervention in Alzheimer's Disease is the use of mimetics of stress to upregulate endogenous protective cascades to repair age damage, shift the balance of apoptosis to regeneration to promote delay of onset, and even progression of Alzheimer's disease memory dysfunction. Mimetics of environmental stress, hormetic agents, and triggers, endogenous or engineered, can “trick” activation of expression patterns of repair and rejuvenation. Examples of known candidate triggers of heat response, endogenous antioxidants, DNA repair, exercise, hibernation, and telomeres are available for AD intervention trials. Telomeres and telomerase emerge as major regulators in crossroads of senescence, cancer, and rejuvenation responsive to mimetics of telomeres. Lessons emerge from transgenic rodent models, the long-lived mole rat, clinical studies, and conserved innate pathways of stress resistance. Cross-reaction of benefits of different triggers promises intervention into seemingly otherwise unrelated diseases.
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Rankin AM, Sarkar S, Faller DV. Mechanism of T-oligo-induced cell cycle arrest in Mia-PaCa pancreatic cancer cells. J Cell Physiol 2012; 227:2586-94. [PMID: 21898405 DOI: 10.1002/jcp.22997] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
DNA oligonucleotides with sequence homology to human telomeric DNA (T-oligo) induce cell cycle arrest, followed by apoptosis, senescence, or autophagy in a human cancer cell type-specific manner. T-oligo has potential as a new therapeutic strategy in oncology because of its ability to target certain types of tumor cells while sparing normal ones. In the present study, we demonstrate the T-oligo-induced S-phase cell cycle arrest in four pancreatic cancer cell lines. To further contribute to the mechanistic understanding of T-oligo, we also identify cyclin dependent kinase 2 (cdk2) as a functional mediator in the T-oligo-induced cell cycle arrest of pancreatic cancer cells. Ectopic expression of a constitutively active cdk2 mutant abrogates T-oligo-induced cell cycle arrest in these tumor cells while knockdown of cdk2 expression alone recapitulates the T-oligo effect. Finally, we demonstrate the dispensability of T-oligo-induced ATM/ATR-mediated DNA damage response-signaling pathways, which have long been considered functional in the T-oligo signaling mechanism.
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Affiliation(s)
- Andrew M Rankin
- Cancer Center, Boston University School of Medicine, Boston, Massachusetts 02118-2307, USA
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Sarkar S, Faller DV. T-oligos inhibit growth and induce apoptosis in human ovarian cancer cells. Oligonucleotides 2011; 21:47-53. [PMID: 21281128 DOI: 10.1089/oli.2010.0259] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Ovarian cancer remains a leading cause of death among women worldwide, and current treatment regimens for advanced disease are inadequate. Oligonucleotides with sequence homology to telomeres (called T-oligos) have been shown to mimic DNA damage responses in cells and induce cytotoxic effects in certain tumor cell lines. We studied the effects of 2 distinct 16 mer T-oligos in 4 human ovarian epithelial carcinoma cell lines. A T-oligo with perfect homology to the telomere overhang region demonstrated some cytotoxic activity in half of the cell lines. A G-rich T-oligo derivative showed more potency and broader cytotoxic activity in these lines than the parental T-oligo. Activation of apoptotic pathways in ovarian cancer cells by exposure to the T-oligo was demonstrated by multiple independent assays. T-oligo was shown to have additive, or more than additive, activity in combination with 2 different histone deacetylase drugs currently in clinical testing. T-oligos may therefore provide a new and tumor-targeted approach to ovarian cancers.
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Affiliation(s)
- Sibaji Sarkar
- Cancer Center, Boston University School of Medicine, Boston, Massachusetts, USA
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Denis GV. Bromodomain coactivators in cancer, obesity, type 2 diabetes, and inflammation. DISCOVERY MEDICINE 2010; 10:489-499. [PMID: 21189220 PMCID: PMC3025494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Double bromodomain proteins bind to acetylated lysines in histones, bringing associated histone modification and nucleosome remodeling activity to chromatin. The ability of bromodomain regulators to alter chromatin status and control gene expression has long been appreciated to be important in the development of certain human cancers. However, bromodomain proteins have now been found also to be critical, non-redundant players in diverse, non-malignant phenotypes, directing transcriptional programs that control adipogenesis, energy metabolism and inflammation. The fact that such different processes are functionally linked by the same molecular machinery suggests a common epigenetic basis to understand and interpret the origins of several important co-morbidities, such as asthma or cancer that occurs in obesity, and complex inflammatory diseases like cardiovascular disease, systemic lupus erythematosus, rheumatoid arthritis and insulin resistance that may be built on a common pro-inflammatory foundation.
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Affiliation(s)
- Gerald V Denis
- Cancer Research Center, Boston University School of Medicine, 72 East Concord Street, K520, Boston, Massachusetts 02118, USA.
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Forsha SJ, Panyutin IV, Neumann RD, Panyutin IG. Intracellular traffic of oligodeoxynucleotides in and out of the nucleus: effect of exportins and DNA structure. Oligonucleotides 2010; 20:277-84. [PMID: 20946012 DOI: 10.1089/oli.2010.0255] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The delivery of oligodeoxynucleotides (ODNs) into cells is widely utilized for antisense, antigene, aptamer, and similar approaches to regulate gene and protein activities based upon the ODNs' sequence-specific recognition. Short pieces of DNA can also be generated in biological processes, for example, after degradation of viral or bacterial DNA. However, the mechanisms that regulate intracellular trafficking and localization of ODNs are not fully understood. Here we study the effects of major transporters of microRNA, exportin-1 (Exp1) and exportin-5 (Exp5), on the transport of single-stranded ODNs in and out of the nucleus. For this, we employed a fluorescent microscopy-based assay to quantitatively measure the redistribution of ODNs between the nucleus and cytoplasm of live cells. By measuring the fluorescent signal of the nuclei we observed that after delivery into cells via cationic liposomes ODNs rapidly accumulated inside nuclei. However, after removal of the ODN/liposome containing media, we found re-localization of ODNs from the nuclei to cytoplasm of the cells over the time course of several hours. Downregulation of the Exp5 gene by siRNA resulted in a slight increase of ODN uptake into the nucleus, but the kinetics of ODN efflux to the cytoplasm was not affected. Inhibition of Exp1 with leptomycin B somewhat slowed down the clearance of ODNs from the nucleus; however, within 6 hours most of the ODN were still being cleared form the nucleus. ODNs that could form intramolecular G-quadruplex structures behaved differently. They also accumulated in nuclei, although at a lesser extent than unstructured ODN, but they remained there for up to 20 hours after transfection, causing significant cell death. We conclude that Exp1 and Exp5 are not the major transporters of our ODNs out of the nucleus, and that the transport of ODNs is strongly affected by their secondary structure.
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Affiliation(s)
- Stephen J Forsha
- Radiology and Imaging Sciences Department, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
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Radiosensitization of mammary carcinoma cells by telomere homolog oligonucleotide pretreatment. Breast Cancer Res 2010; 12:R71. [PMID: 20846433 PMCID: PMC3096958 DOI: 10.1186/bcr2639] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Accepted: 09/16/2010] [Indexed: 12/31/2022] Open
Abstract
Introduction Ionizing radiation (IR) is a widely used approach to cancer therapy, ranking second only to surgery in rate of utilization. Responses of cancer patients to radiotherapy depend in part on the intrinsic radiosensitivity of the tumor cells. Thus, promoting tumor cell sensitivity to IR could significantly enhance the treatment outcome and quality of life for patients. Methods Mammary tumor cells were treated by a 16-base phosphodiester-linked oligonucleotide homologous to the telomere G-rich sequence TTAGGG (T-oligo: GGTTAGGTGTAGGTTT) or a control-oligo (the partial complement, TAACCCTAACCCTAAC) followed by IR. The inhibition of tumor cell growth in vitro was assessed by cell counting and clonogenic cell survival assay. The tumorigenesis of tumor cells after various treatments was measured by tumor growth in mice. The mechanism underlying the radiosensitization by T-oligo was explored by immunofluorescent determination of phosphorylated histone H2AX (γH2AX) foci, β-galactosidase staining, comet and Terminal deoxynucleotidyl transferase dUTP Nick End Labeling (TUNEL) assays. The efficacy of the combined treatment was assessed in a spontaneous murine mammary tumor model. Results Pretreatment of tumor cells with T-oligo for 24 hours in vitro enhanced both senescence and apoptosis of irradiated tumor cells and reduced clonogenic potential. Radiosensitization by T-oligo was associated with increased formation and/or delayed resolution of γH2AX DNA damage foci and fragmented DNA. T-oligo also caused radiosensitization in two in vivo mammary tumor models. Indeed, combined T-oligo and IR-treatment in vivo led to a substantial reduction in tumor growth. Of further significance, treatment with T-oligo and IR led to synergistic inhibition of the growth of spontaneous mammary carcinomas. Despite these profound antitumor properties, T-oligo and IR caused no detectable side effects under our experimental conditions. Conclusions Pretreatment with T-oligo sensitizes mammary tumor cells to radiation in both in vitro and in vivo settings with minimal or no normal tissue side effects.
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Inhibition of melanoma angiogenesis by telomere homolog oligonucleotides. JOURNAL OF ONCOLOGY 2010; 2010:928628. [PMID: 20652008 PMCID: PMC2906154 DOI: 10.1155/2010/928628] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 05/06/2010] [Accepted: 05/07/2010] [Indexed: 01/13/2023]
Abstract
Telomere homolog oligonucleotides (T-oligos) activate an innate telomere-based program that leads to multiple anticancer effects. T-oligos act at telomeres to initiate signaling through the Werner protein and ATM kinase. We wanted to determine if T-oligos have antiangiogenic effects. We found that T-oligo-treated human melanoma (MM-AN) cells had decreased expression of vascular endothelial growth factor (VEGF), VEGF receptor 2, angiopoeitin-1 and -2 and decreased VEGF secretion. T-oligos activated the transcription factor E2F1 and inhibited the activity of the angiogenic transcription factor, HIF-1α. T-oligos inhibited EC tubulogenesis and total tumor microvascular density matrix invasion by MM-AN cells and ECs in vitro. In melanoma SCID xenografts, two systemic T-oligo injections decreased by 60% (P < .004) total tumor microvascular density and the functional vessels density by 80% (P < .002). These findings suggest that restriction of tumor angiogenesis is among the host's innate telomere-based anticancer responses and provide further evidence that T-oligos may offer a powerful new approach for melanoma treatment.
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Abstract
Certain human subpopulations are metabolically healthy but obese, or metabolically obese but normal weight; such mutations uncouple obesity from glucose intolerance, revealing pathways implicated in Type 2 diabetes. Current searches for relevant genes consume significant effort. We have reported previously a novel double bromodomain protein called Brd2, which is a transcriptional co-activator/co-repressor with SWI/SNF (switch mating type/sucrose non-fermenting)-like functions that regulates chromatin. In the present study, we show that wholebody disruption of Brd2, an unusual MHC gene, causes lifelong severe obesity in mice with pancreatic islet expansion, hyperinsulinaemia, hepatosteatosis and elevated pro-inflammatory cytokines, but, surprisingly, enhanced glucose tolerance, elevated adiponectin, increased weight of brown adipose tissue, heat production and expression of mitochondrial uncoupling proteins in brown adipose tissue, reduced macrophage infiltration in white adipose tissue, and lowered blood glucose, leading to an improved metabolic profile and avoiding eventual Type 2 diabetes. Brd2 is highly expressed in pancreatic beta-cells, where it normally inhibits beta-cell mitosis and insulin transcription. In 3T3-L1 pre-adipocytes, Brd2 normally co-represses PPAR-gamma (peroxisome-proliferator-activated receptor-gamma) and inhibits adipogenesis. Brd2 knockdown protects 3T3-L1 adipocytes from TNF-alpha (tumour necrosis factor-alpha)-induced insulin resistance, thereby decoupling inflammation from insulin resistance. Thus hypomorphic Brd2 shifts energy balance toward storage without causing glucose intolerance and may provide a novel model for obese metabolically healthy humans.
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Gnanasekar M, Thirugnanam S, Zheng G, Chen A, Ramaswamy K. T-oligo induces apoptosis in advanced prostate cancer cells. Oligonucleotides 2009; 19:287-92. [PMID: 19642913 DOI: 10.1089/oli.2009.0179] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Prostate cancer is the most frequently diagnosed malignancy in men. As cancer progresses from an androgen-sensitive stage to hormone-refractory stage, it turns resistant to androgen ablation therapy. At this stage, effective newer therapies that induce apoptosis are needed for treatment of prostate cancer. DNA oligonucleotides homologous to the telomere 3' overhang (T-oligo) induce apoptosis in several human cancer cells. In the present study, we studied the effect of T-oligo on prostate cancer cells. Our studies showed that androgen-independent DU-145 cells are sensitive to T-oligo in terms of inhibition of proliferation. Moreover, T-oligo induced DU-145 cells to undergo apoptosis. Therefore, our results are encouraging for further investigation in the potential application of T-oligo as a novel therapeutic approach for prostate cancer, especially the androgen-independent.
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Affiliation(s)
- Munirathinam Gnanasekar
- Department of Biomedical Sciences, University of Illinois, College of Medicine, 1601 Parkview Avenue, Rockford, IL 61107, USA.
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