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Pennisi G, Bruzzaniti P, Burattini B, Piaser Guerrato G, Della Pepa GM, Sturiale CL, Lapolla P, Familiari P, La Pira B, D’Andrea G, Olivi A, D’Alessandris QG, Montano N. Advancements in Telomerase-Targeted Therapies for Glioblastoma: A Systematic Review. Int J Mol Sci 2024; 25:8700. [PMID: 39201386 PMCID: PMC11354571 DOI: 10.3390/ijms25168700] [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: 06/25/2024] [Revised: 07/25/2024] [Accepted: 08/06/2024] [Indexed: 09/02/2024] Open
Abstract
Glioblastoma (GBM) is a primary CNS tumor that is highly lethal in adults and has limited treatment options. Despite advancements in understanding the GBM biology, the standard treatment for GBM has remained unchanged for more than a decade. Only 6.8% of patients survive beyond five years. Telomerase, particularly the hTERT promoter mutations present in up to 80% of GBM cases, represents a promising therapeutic target due to its role in sustaining telomere length and cancer cell proliferation. This review examines the biology of telomerase in GBM and explores potential telomerase-targeted therapies. We conducted a systematic review following the PRISMA-P guidelines in the MEDLINE/PubMed and Scopus databases, from January 1995 to April 2024. We searched for suitable articles by utilizing the terms "GBM", "high-grade gliomas", "hTERT" and "telomerase". We incorporated studies addressing telomerase-targeted therapies into GBM studies, excluding non-English articles, reviews, and meta-analyses. We evaluated a total of 777 records and 46 full texts, including 36 studies in the final review. Several compounds aimed at inhibiting hTERT transcription demonstrated promising preclinical outcomes; however, they were unsuccessful in clinical trials owing to intricate regulatory pathways and inadequate pharmacokinetics. Direct hTERT inhibitors encountered numerous obstacles, including a prolonged latency for telomere shortening and the activation of the alternative lengthening of telomeres (ALT). The G-quadruplex DNA stabilizers appeared to be potential indirect inhibitors, but further clinical studies are required. Imetelstat, the only telomerase inhibitor that has undergone clinical trials, has demonstrated efficacy in various cancers, but its efficacy in GBM has been limited. Telomerase-targeted therapies in GBM is challenging due to complex hTERT regulation and inadequate inhibitor pharmacokinetics. Our study demonstrates that, despite promising preclinical results, no Telomerase inhibitors have been approved for GBM, and clinical trials have been largely unsuccessful. Future strategies may include Telomerase-based vaccines and multi-target inhibitors, which may provide more effective treatments when combined with a better understanding of telomere dynamics and tumor biology. These treatments have the potential to be integrated with existing ones and to improve the outcomes for patients with GBM.
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Affiliation(s)
- Giovanni Pennisi
- Department of Neurosurgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (B.B.); (G.P.G.); (G.M.D.P.); (C.L.S.); (A.O.); (Q.G.D.); (N.M.)
- Department of Neurosurgery, F. Spaziani Hospital, 03100 Frosinone, Italy; (B.L.P.); (G.D.)
| | - Placido Bruzzaniti
- Department of Neurosurgery, F. Spaziani Hospital, 03100 Frosinone, Italy; (B.L.P.); (G.D.)
- Department of Human Neurosciences, Division of Neurosurgery, Policlinico Umberto I University Hospital, Sapienza, University of Rome, 00157 Rome, Italy;
| | - Benedetta Burattini
- Department of Neurosurgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (B.B.); (G.P.G.); (G.M.D.P.); (C.L.S.); (A.O.); (Q.G.D.); (N.M.)
| | - Giacomo Piaser Guerrato
- Department of Neurosurgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (B.B.); (G.P.G.); (G.M.D.P.); (C.L.S.); (A.O.); (Q.G.D.); (N.M.)
| | - Giuseppe Maria Della Pepa
- Department of Neurosurgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (B.B.); (G.P.G.); (G.M.D.P.); (C.L.S.); (A.O.); (Q.G.D.); (N.M.)
| | - Carmelo Lucio Sturiale
- Department of Neurosurgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (B.B.); (G.P.G.); (G.M.D.P.); (C.L.S.); (A.O.); (Q.G.D.); (N.M.)
| | | | - Pietro Familiari
- Department of Human Neurosciences, Division of Neurosurgery, Policlinico Umberto I University Hospital, Sapienza, University of Rome, 00157 Rome, Italy;
| | - Biagia La Pira
- Department of Neurosurgery, F. Spaziani Hospital, 03100 Frosinone, Italy; (B.L.P.); (G.D.)
| | - Giancarlo D’Andrea
- Department of Neurosurgery, F. Spaziani Hospital, 03100 Frosinone, Italy; (B.L.P.); (G.D.)
| | - Alessandro Olivi
- Department of Neurosurgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (B.B.); (G.P.G.); (G.M.D.P.); (C.L.S.); (A.O.); (Q.G.D.); (N.M.)
| | - Quintino Giorgio D’Alessandris
- Department of Neurosurgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (B.B.); (G.P.G.); (G.M.D.P.); (C.L.S.); (A.O.); (Q.G.D.); (N.M.)
| | - Nicola Montano
- Department of Neurosurgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (B.B.); (G.P.G.); (G.M.D.P.); (C.L.S.); (A.O.); (Q.G.D.); (N.M.)
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Relitti N, Saraswati AP, Federico S, Khan T, Brindisi M, Zisterer D, Brogi S, Gemma S, Butini S, Campiani G. Telomerase-based Cancer Therapeutics: A Review on their Clinical Trials. Curr Top Med Chem 2020; 20:433-457. [PMID: 31894749 DOI: 10.2174/1568026620666200102104930] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 12/02/2019] [Accepted: 12/03/2019] [Indexed: 12/11/2022]
Abstract
Telomeres are protective chromosomal ends that shield the chromosomes from DNA damage, exonucleolytic degradation, recombination, and end-to-end fusion. Telomerase is a ribonucleoprotein that adds TTAGGG tandem repeats to the telomeric ends. It has been observed that 85 to 90% of human tumors express high levels of telomerase, playing a crucial role in the development of cancers. Interestingly, the telomerase activity is generally absent in normal somatic cells. This selective telomerase expression has driven scientists to develop novel anti-cancer therapeutics with high specificity and potency. Several advancements have been made in this area, which is reflected by the enormous success of the anticancer agent Imetelstat. Since the discovery of Imetelstat, several research groups have contributed to enrich the therapeutic arsenal against cancer. Such contributions include the application of new classes of small molecules, peptides, and hTERT-based immunotherapeutic agents (p540, GV1001, GRNVAC1 or combinations of these such as Vx-001). Many of these therapeutic tools are under different stages of clinical trials and have shown promising outcomes. In this review, we highlight the current status of telomerase-based cancer therapeutics and the outcome of these investigations.
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Affiliation(s)
- Nicola Relitti
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022, via Aldo Moro 2, I- 53100 Siena, University of Siena, Siena, Italy
| | - Akella P Saraswati
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022, via Aldo Moro 2, I- 53100 Siena, University of Siena, Siena, Italy
| | - Stefano Federico
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022, via Aldo Moro 2, I- 53100 Siena, University of Siena, Siena, Italy
| | - Tuhina Khan
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022, via Aldo Moro 2, I- 53100 Siena, University of Siena, Siena, Italy
| | - Margherita Brindisi
- Department of Pharmacy, Department of Excellence 2018-2022, University of Napoli Federico II, via D. Montesano 49, I-80131 Napoli, Italy
| | - Daniela Zisterer
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, 152-160, Pearse Street, Dublin 2, Ireland
| | - Simone Brogi
- Department of Pharmacy, University of Pisa, via Bonanno Pisano 6, I-56126 Pisa, Italy
| | - Sandra Gemma
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022, via Aldo Moro 2, I- 53100 Siena, University of Siena, Siena, Italy
| | - Stefania Butini
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022, via Aldo Moro 2, I- 53100 Siena, University of Siena, Siena, Italy
| | - Giuseppe Campiani
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022, via Aldo Moro 2, I- 53100 Siena, University of Siena, Siena, Italy
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3
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Ramos AD, Magge RS, Ramakrishna R. Molecular Pathogenesis and Emerging Treatment for Glioblastoma. World Neurosurg 2018; 116:495-504. [DOI: 10.1016/j.wneu.2018.04.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 03/13/2018] [Indexed: 12/18/2022]
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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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Abstract
Oligonucleotide-based therapeutics have made rapid progress in the clinic for treatment of a variety of disease indications. Unmodified oligonucleotides are polyanionic macromolecules with poor drug-like properties. Over the past two decades, medicinal chemists have identified a number of chemical modification and conjugation strategies which can improve the nuclease stability, RNA-binding affinity, and pharmacokinetic properties of oligonucleotides for therapeutic applications. In this perspective, we present a summary of the most commonly used nucleobase, sugar and backbone modification, and conjugation strategies used in oligonucleotide medicinal chemistry.
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Affiliation(s)
- W Brad Wan
- Department of Medicinal Chemistry, Ionis Pharmaceuticals , 2855 Gazelle Court, Carlsbad, California 92010, United States
| | - Punit P Seth
- Department of Medicinal Chemistry, Ionis Pharmaceuticals , 2855 Gazelle Court, Carlsbad, California 92010, United States
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Hung NA, Eiholzer RA, Kirs S, Zhou J, Ward-Hartstonge K, Wiles AK, Frampton CM, Taha A, Royds JA, Slatter TL. Telomere profiles and tumor-associated macrophages with different immune signatures affect prognosis in glioblastoma. Mod Pathol 2016; 29:212-26. [PMID: 26769142 DOI: 10.1038/modpathol.2015.156] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Revised: 11/18/2015] [Accepted: 11/20/2015] [Indexed: 01/02/2023]
Abstract
Telomere maintenance is a hallmark of cancer and likely to be targeted in future treatments. In glioblastoma established methods of identifying telomerase and alternative lengthening of telomeres leave a significant proportion of tumors with no defined telomere maintenance mechanism. This study investigated the composition of these tumors using RNA-Seq. Glioblastomas with an indeterminate telomere maintenance mechanism had an increased immune signature compared with alternative lengthening of telomeres and telomerase-positive tumors. Immunohistochemistry for CD163 confirmed that the majority (80%) of tumors with an indeterminate telomere maintenance mechanism had a high presence of tumor-associated macrophages. The RNA-Seq and immunostaining data separated tumors with no defined telomere maintenance mechanism into three subgroups: alternative lengthening of telomeres like tumors with a high presence of tumor-associated macrophages and telomerase like tumors with a high presence of tumor-associated macrophages. The third subgroup had no increase in tumor-associated macrophages and may represent a distinct category. The presence of tumor-associated macrophages conferred a worse prognosis with reduced patient survival times (alternative lengthening of telomeres with and without macrophages P=0.0004, and telomerase with and without macrophages P=0.013). The immune signatures obtained from RNA-Seq were significantly different between telomere maintenance mechanisms. Alternative lengthening of telomeres like tumors with macrophages had increased expression of interferon-induced proteins with tetratricopeptide repeats (IFIT1-3). Telomerase-positive tumors with macrophages had increased expression of macrophage receptor with collagenous structure (MARCO), CXCL12 and sushi-repeat containing protein x-linked 2 (SRPX2). Telomerase-positive tumors with macrophages were also associated with a reduced frequency of total/near total resections (44% vs >76% for all other subtypes, P=0.014). In summary, different immune signatures are found among telomere maintenance mechanism-based subgroups in glioblastoma. The reduced extent of surgical resection of telomerase-positive tumors with macrophages suggests that some tumor-associated macrophages are more unfavorable.
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Affiliation(s)
- Noelyn A Hung
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Ramona A Eiholzer
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Stenar Kirs
- Department of Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Jean Zhou
- Department of Radiology, Southern District Health Board, Dunedin, New Zealand
| | - Kirsten Ward-Hartstonge
- Department of Microbiology and Immunology, Dunedin School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Anna K Wiles
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Chris M Frampton
- Department of Medicine, University of Otago, Christchurch, New Zealand
| | - Ahmad Taha
- Neurosurgery, Southern District Health Board, Dunedin, New Zealand
| | - Janice A Royds
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Tania L Slatter
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
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Ferrandon S, Malleval C, El Hamdani B, Battiston-Montagne P, Bolbos R, Langlois JB, Manas P, Gryaznov SM, Alphonse G, Honnorat J, Rodriguez-Lafrasse C, Poncet D. Telomerase inhibition improves tumor response to radiotherapy in a murine orthotopic model of human glioblastoma. Mol Cancer 2015; 14:134. [PMID: 26183089 PMCID: PMC4504179 DOI: 10.1186/s12943-015-0376-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 05/01/2015] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Glioblastoma (GBM) is the most frequent and aggressive type of adult brain tumor. Most GBMs express telomerase; a high level of intra-tumoral telomerase activity (TA) is predictive of poor prognosis. Thus, telomerase inhibitors are promising options to treat GBM. These inhibitors increase the response to radiotherapy (RT), in vitro as well as in vivo. Since typical treatments for GBM include RT, our objective was to evaluate the efficiency of Imetelstat (TA inhibitor) combined with RT. FINDINGS We used a murine orthotopic model of human GBM (N = 8 to11 mice per group) and μMRI imaging to evaluate the efficacy of Imetelstat (delivered by intra-peritoneal injection) alone and combined with RT. Using a clinically established protocol, we demonstrated that Imetelstat significantly: (i) inhibited the TA in the very center of the tumor, (ii) reduced tumor volume as a proportion of TA inhibition, and (iii) increased the response to RT, in terms of tumor volume regression and survival increase. CONCLUSIONS Imetelstat is currently evaluated in refractory brain tumors in young patients (without RT). Our results support its clinical evaluation combined with RT to treat GBM.
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Affiliation(s)
- Sylvain Ferrandon
- EMR3738, Cellular and Molecular Radiobiology Laboratory, South Lyon Charles Mérieux Medicine Faculty, Oullins, France. .,Université Claude Bernard Lyon 1, Lyon, France.
| | - Céline Malleval
- Team « neuro-oncology and neuro-inflammation », Lyon Neuroscience Research Center, INSERM U1028/CNRS UMR 5292, Laennec Medicine Faculty, Lyon, France.
| | - Badia El Hamdani
- EMR3738, Cellular and Molecular Radiobiology Laboratory, South Lyon Charles Mérieux Medicine Faculty, Oullins, France. .,Hospices Civils de Lyon, South Lyon Hospital, Pierre Bénite, France.
| | - Priscillia Battiston-Montagne
- EMR3738, Cellular and Molecular Radiobiology Laboratory, South Lyon Charles Mérieux Medicine Faculty, Oullins, France. .,Université Claude Bernard Lyon 1, Lyon, France.
| | - Radu Bolbos
- CERMEP-imagerie du vivant, Groupement Hospitalier Est, Bron, France.
| | | | - Patrick Manas
- UMS 3444 gerland CNRS P.B.E.S - Ecole Normale Supérieure Lyon, Lyon, France.
| | - Sergei M Gryaznov
- Geron Corporation, 149 Commonweath Drive, Menlo, Park, CA, 94025, USA.
| | - Gersende Alphonse
- EMR3738, Cellular and Molecular Radiobiology Laboratory, South Lyon Charles Mérieux Medicine Faculty, Oullins, France. .,Hospices Civils de Lyon, South Lyon Hospital, Pierre Bénite, France.
| | - Jérôme Honnorat
- Université Claude Bernard Lyon 1, Lyon, France. .,Team « neuro-oncology and neuro-inflammation », Lyon Neuroscience Research Center, INSERM U1028/CNRS UMR 5292, Laennec Medicine Faculty, Lyon, France. .,Department of neuro-oncology, Hospices civils de Lyon, Bron, France.
| | - Claire Rodriguez-Lafrasse
- EMR3738, Cellular and Molecular Radiobiology Laboratory, South Lyon Charles Mérieux Medicine Faculty, Oullins, France. .,Université Claude Bernard Lyon 1, Lyon, France. .,Biochemistry Department, Transfer and Molecular Oncology Unit, South Lyon Hospital, Hospices Civils de Lyon, Pierre Bénite, France.
| | - Delphine Poncet
- EMR3738, Cellular and Molecular Radiobiology Laboratory, South Lyon Charles Mérieux Medicine Faculty, Oullins, France. .,Université Claude Bernard Lyon 1, Lyon, France. .,Biochemistry Department, Transfer and Molecular Oncology Unit, South Lyon Hospital, Hospices Civils de Lyon, Pierre Bénite, France.
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Itakura G, Kobayashi Y, Nishimura S, Iwai H, Takano M, Iwanami A, Toyama Y, Okano H, Nakamura M. Control of the Survival and Growth of Human Glioblastoma Grafted Into the Spinal Cord of Mice by Taking Advantage of Immunorejection. Cell Transplant 2014; 24:1299-311. [PMID: 24818989 DOI: 10.3727/096368914x681711] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Recent studies have demonstrated that transplantation of induced pluripotent stem cell-derived neurospheres can promote functional recovery after spinal cord injury in rodents, as well as in nonhuman primates. However, the potential tumorigenicity of the transplanted cells remains a matter of apprehension prior to clinical applications. As a first step to overcome this concern, this study established a glioblastoma multiforme xenograft model mouse. The feasibility of controlling immune suppression to ablate the grafted cells was then investigated. The human glioblastoma multiforme cell line U251 MG was transplanted into the intact spinal cords of immunodeficient NOD/SCID mice or into those of immunocompetent C57BL/6J H-2kb mice treated with or without immunosuppressants [FK506 plus anticluster of differentiation (CD) 4 antibody (Ab), or FK506 alone]. In vivo bioluminescent imaging was used to evaluate the chronological survival of the transplanted cells. The graft survival rate was 100% (n = 9/9) in NOD/SCID mice, 0% (n = 6/6) in C57BL/6J mice without immunosuppressant treatment, and 100% (n = 37/37) in C57BL6/J mice with immunosuppressant treatment. After confirming the growth of the grafted cells in the C57/BL6J mice treated with immunosuppressants, immune suppression was discontinued. The grafted cells were subsequently rejected within 3 days in C57BL/6J mice treated with FK506 alone, as opposed to 26 days in C57BL/6J mice treated with FK506 plus anti-CD4 Ab. Histological evaluation confirmed the ablation of the grafted cells. Although this work describes a xenograft setting, the results suggest that this immunomodulatory strategy could provide a safety lock against tumor formation stemming from transplanted cells.
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Affiliation(s)
- Go Itakura
- Department of Orthopaedic Surgery, Keio University School of Medicine, Shinjuku, Tokyo, Japan
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Telomerase: target for cancer treatment. Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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van Woensel M, Wauthoz N, Rosière R, Amighi K, Mathieu V, Lefranc F, van Gool SW, de Vleeschouwer S. Formulations for Intranasal Delivery of Pharmacological Agents to Combat Brain Disease: A New Opportunity to Tackle GBM? Cancers (Basel) 2013; 5:1020-48. [PMID: 24202332 PMCID: PMC3795377 DOI: 10.3390/cancers5031020] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Revised: 06/29/2013] [Accepted: 08/02/2013] [Indexed: 01/01/2023] Open
Abstract
Despite recent advances in tumor imaging and chemoradiotherapy, the median overall survival of patients diagnosed with glioblastoma multiforme does not exceed 15 months. Infiltration of glioma cells into the brain parenchyma, and the blood-brain barrier are important hurdles to further increase the efficacy of classic therapeutic tools. Local administration methods of therapeutic agents, such as convection enhanced delivery and intracerebral injections, are often associated with adverse events. The intranasal pathway has been proposed as a non-invasive alternative route to deliver therapeutics to the brain. This route will bypass the blood-brain barrier and limit systemic side effects. Upon presentation at the nasal cavity, pharmacological agents reach the brain via the olfactory and trigeminal nerves. Recently, formulations have been developed to further enhance this nose-to-brain transport, mainly with the use of nanoparticles. In this review, the focus will be on formulations of pharmacological agents, which increase the nasal permeation of hydrophilic agents to the brain, improve delivery at a constant and slow release rate, protect therapeutics from degradation along the pathway, increase mucoadhesion, and facilitate overall nasal transport. A mounting body of evidence is accumulating that the underexplored intranasal delivery route might represent a major breakthrough to combat glioblastoma.
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Affiliation(s)
- Matthias van Woensel
- Laboratory of Experimental Neurosurgery and Neuroanatomy, KU Leuven, Leuven 3000, Belgium; E-Mail:
- Laboratory of Pediatric Immunology, KU Leuven, Leuven 3000, Belgium; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +32-016-34-61-65; Fax: +32-016-34-60-35
| | - Nathalie Wauthoz
- Laboratory of Pharmaceutics and Biopharmaceutics, ULB, Brussels 1050, Belgium; E-Mails: (N.W.); (R.R.); (K.A.)
| | - Rémi Rosière
- Laboratory of Pharmaceutics and Biopharmaceutics, ULB, Brussels 1050, Belgium; E-Mails: (N.W.); (R.R.); (K.A.)
| | - Karim Amighi
- Laboratory of Pharmaceutics and Biopharmaceutics, ULB, Brussels 1050, Belgium; E-Mails: (N.W.); (R.R.); (K.A.)
| | - Véronique Mathieu
- Laboratory of Toxicology, ULB, Brussels 1050, Belgium; E-Mails: (V.M.); (F.L.)
| | - Florence Lefranc
- Laboratory of Toxicology, ULB, Brussels 1050, Belgium; E-Mails: (V.M.); (F.L.)
- Department of Neurosurgery, Erasmus University Hospitals, Brussels 1050, Belgium
| | - Stefaan W. van Gool
- Laboratory of Pediatric Immunology, KU Leuven, Leuven 3000, Belgium; E-Mail:
| | - Steven de Vleeschouwer
- Laboratory of Experimental Neurosurgery and Neuroanatomy, KU Leuven, Leuven 3000, Belgium; E-Mail:
- Laboratory of Pediatric Immunology, KU Leuven, Leuven 3000, Belgium; E-Mail:
- Department of Neurosurgery, University Hospitals Leuven, Leuven 3000, Belgium
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Expression of telomeres in astrocytoma WHO grade 2 to 4: TERRA level correlates with telomere length, telomerase activity, and advanced clinical grade. Transl Oncol 2012; 5:56-65. [PMID: 22348177 DOI: 10.1593/tlo.11202] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 10/20/2011] [Accepted: 10/25/2011] [Indexed: 12/19/2022] Open
Abstract
Cancer cells bypass replicative senescence, the major barrier to tumor progression, by using telomerase or alternative lengthening of telomeres (ALT) as telomere maintenance mechanisms (TMMs). Correlation between ALT and patient survival was demonstrated for high-grade astrocytomas. Transcription from subtelomeres produces telomeric repeat-containing RNA (TERRA), a natural inhibitor of telomerase activity (TA). This led us to evaluate correlations of TERRA and TMM with tumor grade and outcome in astrocytoma patients. SYBR Green real-time reverse transcription-polymerase chain reaction assays for quantitation of total and chromosome 2p and 18p specific TERRA levels were developed. Tumor samples from 46 patients with astrocytoma grade 2 to 4, tissue controls, and cell lines were assessed. TMMs were evaluated by measuring TA and by detecting long telomeres due to ALT. In glioblastoma multiforme (GBM) grade 4, total TERRA levels were similar to cell lines but 14-, 31-, and 313-fold lower compared with grade 3, grade 2, and nonmalignant tissue, respectively. Total TERRA levels differed from chromosomal levels. Low 2p TERRA levels correlated with dense promoter methylation of subtelomeric CpG islands, indicating that TERRA expression in gliomas may be chromosome specific and epigenetically regulated. Total TERRA levels correlated with diagnosis, with low or absent TA and the presence of ALT, and were tentatively associated with favorable patient prognosis in our cohort (P = .06). TA and short telomeres identified a subset of GBM with a median survival of only 14.8 months. TERRA and TA may be prognostic in astrocytic tumors.
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Hjelmeland AB, Rich JN. Molecular targeting of neural cancer stem cells: TTAGGG, you're it! Clin Cancer Res 2011; 17:3-5. [PMID: 21208901 DOI: 10.1158/1078-0432.ccr-10-2686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Telomerase is an important mechanism by which cancers escape replicative senescence. In neural tumors, cancer stem cells express telomerase, suggesting that this may explain their preferential tumorigenesis. Oligonucleotide telomerase targeting selectively disrupts cancer stem cell growth through the induction of differentiation, adding to the armamentarium of anticancer stem cell therapies.
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Affiliation(s)
- Anita B Hjelmeland
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
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13
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Buseman CM, Wright WE, Shay JW. Is telomerase a viable target in cancer? Mutat Res 2011; 730:90-7. [PMID: 21802433 DOI: 10.1016/j.mrfmmm.2011.07.006] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 06/20/2011] [Accepted: 07/11/2011] [Indexed: 02/08/2023]
Abstract
The ideal cancer treatment would specifically target cancer cells yet have minimal or no adverse effects on normal somatic cells. Telomerase, the ribonucleoprotein reverse transcriptase that maintains the ends of human chromosome, is an attractive cancer therapeutic target for exactly this reason [1]. Telomerase is expressed in more than 85% of cancer cells, making it a nearly universal cancer marker, while the majority of normal somatic cells are telomerase negative. Telomerase activity confers limitless replicative potential to cancer cells, a hallmark of cancer which must be attained for the continued growth that characterizes almost all advanced neoplasms [2]. In this review we will summarize the role of telomeres and telomerase in cancer cells, and how properties of telomerase are being exploited to create targeted cancer therapies including telomerase inhibitors, telomerase-targeted immunotherapies and telomerase-driven virotherapies. A frank and balanced assessment of the current state of telomerase inhibitors with caveats and potential limitations will be included.
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Affiliation(s)
- C M Buseman
- The University of Texas Southwestern Medical Center, Department of Cell Biology, Dallas, TX 75390-9039, USA
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14
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Abstract
Malignant gliomas are the most common and aggressive form of brain tumors. Current therapy consists of surgical resection, followed by radiation therapy and concomitant chemotherapy. Despite these treatments, the prognosis for patients is poor. As such, investigative therapies including tumor vaccines have targeted this devastating condition. Recent clinical trials involving immunotherapy, specifically dendritic cell (DC) based vaccines, have shown promising results. Overall, these vaccines are well tolerated with few documented side effects. In many patients receiving vaccines, tumor progression was delayed and the median overall survival of these patients was prolonged. Despite these encouraging results, several factors have limited the efficacy of DC vaccines. Here we discuss the potential of DC vaccines as adjuvant therapy and current obstacles of generating highly pure and potent DC vaccines in the context of malignant glioma. Taken together, the results from earlier clinical studies justify additional clinical trials aimed at improving the efficacy of DC vaccines.
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15
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Harn HJ, Lin SZ, Lin PC, Liu CY, Liu PY, Chang LF, Yen SY, Hsieh DK, Liu FC, Tai DF, Chiou TW. Local interstitial delivery of z-butylidenephthalide by polymer wafers against malignant human gliomas. Neuro Oncol 2011; 13:635-48. [PMID: 21565841 DOI: 10.1093/neuonc/nor021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We have shown that the natural compound z-butylidenephthalide (Bdph), isolated from the chloroform extract of Angelica sinensis, has antitumor effects. Because of the limitation of the blood-brain barrier, the Bdph dosage required for treatment of glioma is relatively high. To solve this problem, we developed a local-release system with Bdph incorporated into a biodegradable polyanhydride material, p(CPP-SA; Bdph-Wafer), and investigated its antitumor effects. On the basis of in vitro release kinetics, we demonstrated that the Bdph-Wafer released 50% of the available Bdph by the sixth day, and the release reached a plateau phase (90% of Bdph) by the 30th day. To investigate the in situ antitumor effects of the Bdph-Wafer on glioblastoma multiforme (GBM), we used 2 xenograft animal models-F344 rats (for rat GBM) and nude mice (for human GBM)-which were injected with RG2 and DBTRG-05MG cells, respectively, for tumor formation and subsequently treated subcutaneously with Bdph-Wafers. We observed a significant inhibitory effect on tumor growth, with no significant adverse effects on the rodents. Moreover, we demonstrated that the antitumor effect of Bdph on RG2 cells was via the PKC pathway, which upregulated Nurr77 and promoted its translocation from the nucleus to the cytoplasm. Finally, to study the effect of the interstitial administration of Bdph in cranial brain tumor, Bdph-Wafers were surgically placed in FGF-SV40 transgenic mice. Our Bdph-Wafer significantly reduced tumor size in a dose-dependent manner. In summary, our study showed that p(CPP-SA) containing Bdph delivered a sufficient concentration of Bdph to the tumor site and effectively inhibited the tumor growth in the glioma.
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Affiliation(s)
- Horng-Jyh Harn
- Department of Pathology, China Medical University Hospital, Taichung, Taiwan, Republic of China
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16
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Lin PC, Lin SZ, Chen YL, Chang JS, Ho LI, Liu PY, Chang LF, Harn YC, Chen SP, Sun LY, Huang PC, Chein JT, Tsai CH, Chou CW, Harn HJ, Chiou TW. Butylidenephthalide suppresses human telomerase reverse transcriptase (TERT) in human glioblastomas. Ann Surg Oncol 2011; 18:3514-27. [PMID: 21553143 DOI: 10.1245/s10434-011-1644-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Indexed: 12/29/2022]
Abstract
BACKGROUND Telomerase is widely expressed in most human cancers, but is almost undetectable in normal somatic cells and is therefore a potential drug target. Using the human telomerase promoter platform, the naturally occurring compound butylidenephthalide (BP) was selected for subsequent investigation of antitumor activity in vitro and in vivo. METHODS We treated human glioblastoma cells with BP and found a dose-dependent decrease in human telomerase reverse transcriptase (hTERT) mRNA expression and a concomitant increase in p16 and p21 expression. Because c-Myc and Sp1 are involved in transcriptional regulation of hTERT, the effect of BP on c-Myc and Sp1 expression was examined. RESULTS Using electrophoretic mobility shift assays and western blotting, we showed that BP represses hTERT transcriptional activity via downregulation of Sp1 expression. Using the telomerase repeat amplification protocol, an association between BP concentration and suppression of telomerase activity, induction of human glioblastoma senescence, and inhibition of cellular proliferation was identified. This was supported by a mouse xenograft model, in which BP repressed telomerase and inhibited tumor proliferation, resulting in tumor senescence. Overexpression of hTERT restored telomerase activity in human glioblastoma cells and overcame replicative senescence. CONCLUSIONS These findings suggest that BP inhibits proliferation and induces senescence in human glioblastomas by downregulating hTERT expression and consequently telomerase activity. This is the first study to describe regulation of telomerase activity by BP in human glioblastomas.
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Affiliation(s)
- Po-Cheng Lin
- Department of Life Science and Graduate Institute of Biotechnology, National Dong Hwa University, Hualien, Taiwan, Republic of China
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17
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Marian CO, Wright WE, Shay JW. The effects of telomerase inhibition on prostate tumor-initiating cells. Int J Cancer 2010; 127:321-31. [PMID: 19908230 DOI: 10.1002/ijc.25043] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Prostate cancer is the most common malignancy in men, and patients with metastatic disease have poor outcome even with the most advanced therapeutic approaches. Most cancer therapies target the bulk tumor cells, but may leave intact a small population of tumor-initiating cells (TICs), which are believed to be responsible for the subsequent relapse and metastasis. Using specific surface markers (CD44, integrin alpha(2)beta(1) and CD133), Hoechst 33342 dye exclusion, and holoclone formation, we isolated TICs from a panel of prostate cancer cell lines (DU145, C4-2 and LNCaP). We have found that prostate TICs have significant telomerase activity which is inhibited by imetelstat sodium (GRN163L), a new telomerase antagonist that is currently in Phase I/II clinical trials for several hematological and solid tumor malignancies. Prostate TICs telomeres were of similar average length to the telomeres of the main population of cells and significant telomere shortening was detected in prostate TICs as a result of imetelstat treatment. These findings suggest that telomerase inhibition therapy may be able to efficiently target the prostate TICs in addition to the bulk tumor cells, providing new opportunities for combination therapies.
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Affiliation(s)
- Calin O Marian
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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18
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Abstract
Telomeres and telomerase play essential roles in the regulation of the lifespan of human cells. While normal human somatic cells do not or only transiently express telomerase and therefore shorten their telomeres with each cell division, most human cancer cells typically express high levels of telomerase and show unlimited cell proliferation. High telomerase expression allows cells to proliferate and expand long-term and therefore supports tumor growth. Owing to the high expression and its role, telomerase has become an attractive diagnostic and therapeutic cancer target. Imetelstat (GRN163L) is a potent and specific telomerase inhibitor and so far the only drug of its class in clinical trials. Here, we report on the structure and the mechanism of action of imetelstat as well as about the preclinical and clinical data and future prospects using imetelstat in cancer therapy.
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19
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Hashizume R, Ozawa T, Dinca EB, Banerjee A, Prados MD, James CD, Gupta N. A human brainstem glioma xenograft model enabled for bioluminescence imaging. J Neurooncol 2009; 96:151-9. [PMID: 19585223 PMCID: PMC2808534 DOI: 10.1007/s11060-009-9954-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 06/22/2009] [Indexed: 11/17/2022]
Abstract
Despite the use of radiation and chemotherapy, the prognosis for children with diffuse brainstem gliomas is extremely poor. There is a need for relevant brainstem tumor models that can be used to test new therapeutic agents and delivery systems in pre-clinical studies. We report the development of a brainstem-tumor model in rats and the application of bioluminescence imaging (BLI) for monitoring tumor growth and response to therapy as part of this model. Luciferase-modified human glioblastoma cells from five different tumor cell sources (either cell lines or serially-passaged xenografts) were implanted into the pontine tegmentum of athymic rats using an implantable guide-screw system. Tumor growth was monitored by BLI and tumor volume was calculated by three-dimensional measurements from serial histopathologic sections. To evaluate if this model would allow detection of therapeutic response, rats bearing brainstem U-87 MG or GS2 glioblastoma xenografts were treated with the DNA methylating agent temozolomide (TMZ). For each of the tumor cell sources tested, BLI monitoring revealed progressive tumor growth in all animals, and symptoms caused by tumor burden were evident 26–29 days after implantation of U-87 MG, U-251 MG, GBM6, and GBM14 cells, and 37–47 days after implantation of GS2 cells. Histopathologic analysis revealed tumor growth within the pons in all rats and BLI correlated quantitatively with tumor volume. Variable infiltration was evident among the different tumors, with GS2 tumor cells exhibiting the greatest degree of infiltration. TMZ treatment groups were included for experiments involving U-87 MG and GS2 cells, and in each case TMZ delayed tumor growth, as indicated by BLI monitoring, and significantly extended survival of animal subjects. Our results demonstrate the development of a brainstem tumor model in athymic rats, in which tumor growth and response to therapy can be accurately monitored by BLI. This model is well suited for pre-clinical testing of therapeutics that are being considered for treatment of patients with brainstem tumors.
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Affiliation(s)
- Rintaro Hashizume
- Department of Neurological Surgery, Brain Tumor Research Center, University of California, 505 Parnassus Ave., Room M779, San Francisco, CA 94143-0112, USA
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20
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Telomerase inhibitors and 'T-oligo' as cancer therapeutics: contrasting molecular mechanisms of cytotoxicity. Anticancer Drugs 2008; 19:329-38. [PMID: 18454043 DOI: 10.1097/cad.0b013e3282f5d4c2] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Telomeres, the specialized structures that comprise the ends of chromosomes, form a closed structure, or t-loop, that is important in preventing genomic instability. Forced modulation of this structure, via overexpression of a dominant-negative form of telomere repeat binding factor 2, a protein critical for maintaining t-loop structure, for example, can result in the activation of DNA-damage responses, and ultimately cellular senescence or apoptosis. This response is also seen in normal somatic cells, where telomeres steadily decrease in length as cellular proliferation occurs owing to inefficient replication of terminal telomeric DNA. When telomere length becomes critically short, t-loop structure is compromised, and the cell undergoes senescence. Telomerase, the enzyme responsible for telomere length maintenance, is overexpressed in a majority of cancers. Its lack of expression in most normal somatic cells makes it an attractive target in designing cancer therapeutics. Compounds currently under development that seek to inhibit hTERT, the reverse transcriptase component of telomerase, include nucleoside analogs and the small molecule BIBR1532. Compounds inhibiting the RNA component of telomerase, hTERC, include peptide nucleic acids, 2-5A antisense oligonucleotides, and N3'-P5' thio-phosphoramidates. Recently, an oligonucleotide sharing sequence homology with terminal telomeric DNA, termed 'T-oligo', has shown cytotoxic effects in multiple cancers in culture and animal models. Independent of telomerase function, T-oligo is thought to mimic the DNA-damage response a cell normally experiences when the telomere t-loop structure becomes dysfunctional. In this review, the molecular mechanisms attributed to telomerase inhibitors and T-oligo, as well as their potential as cancer therapeutics, are discussed.
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21
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Abstract
Long-lived organisms such as humans have evolved several intrinsic tumour suppressor mechanisms to combat the slew of oncogenic somatic mutations that constantly arise in proliferating stem-cell compartments. One of these anticancer barriers is the telomere, a specialized nucleoprotein complex that caps the ends of eukaryotic chromosome. Impaired telomere function activates the canonical DNA damage response pathway that engages p53 to initiate apoptosis or replicative senescence. Here, we discuss how p53-dependent senescence induced by dysfunctional telomeres may be as potent as apoptosis in suppressing tumorigenesis in vivo.
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Affiliation(s)
- Yibin Deng
- Department of Cancer Genetics, Box 1010, The UT M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 USA
| | - Suzanne Chan
- Department of Cancer Genetics, Box 1010, The UT M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 USA
| | - Sandy Chang
- Department of Cancer Genetics, Box 1010, The UT M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 USA
- Department of Hematopathology, The UT M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 USA
- Correspondence:
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22
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Abstract
Telomerase is an attractive cancer target as it appears to be required in essentially all tumours for immortalization of a subset of cells, including cancer stem cells. Moreover, differences in telomerase expression, telomere length and cell kinetics between normal and tumour tissues suggest that targeting telomerase would be relatively safe. Clinical trials are ongoing with a potent and specific telomerase inhibitor, GRN163L, and with several versions of telomerase therapeutic vaccines. The prospect of adding telomerase-based therapies to the growing list of new anticancer products is promising, but what are the advantages and limitations of different approaches, and which patients are the most likely to respond?
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Affiliation(s)
- Calvin B Harley
- Geron Corporation, 230 Constitution Drive, Menlo Park, California 94025, USA.
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23
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Hashizume R, Ozawa T, Gryaznov SM, Bollen AW, Lamborn KR, Frey WH, Deen DF. New therapeutic approach for brain tumors: Intranasal delivery of telomerase inhibitor GRN163. Neuro Oncol 2008; 10:112-20. [PMID: 18287341 DOI: 10.1215/15228517-2007-052] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The blood-brain barrier is a substantial obstacle for delivering anticancer agents to brain tumors, and new strategies for bypassing it are greatly needed for brain-tumor therapy. Intranasal delivery provides a practical, noninvasive method for delivering therapeutic agents to the brain and could provide an alternative to intravenous injection and convection-enhanced delivery. We treated rats bearing intracerebral human tumor xenografts intranasally with GRN163, an oligonucleotide N3'-->P5'thio-phosphoramidate telomerase inhibitor. 3'-Fuorescein isothiocyanate (FITC)-labeled GRN163 was administered intranasally every 2 min as 6 microl drops into alternating sides of the nasal cavity over 22 min. FITC-labeled GRN163 was present in tumor cells at all time points studied, and accumulation of GRN163 peaked at 4 h after delivery. Moreover, GRN163 delivered intranasally, daily for 12 days, significantly prolonged the median survival from 35 days in the control group to 75.5 days in the GRN163-treated group. Thus, intranasal delivery of GRN163 readily bypassed the blood-brain barrier, exhibited favorable tumor uptake, and inhibited tumor growth, leading to a prolonged lifespan for treated rats compared to controls. This delivery approach appears to kill tumor cells selectively, and no toxic effects were noted in normal brain tissue. These data support further development of intranasal delivery of tumor-specific therapeutic agents for brain tumor patients.
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Affiliation(s)
- Rintaro Hashizume
- Brain Tumor Research Center, Department of Neurological Surgery, University of California San Francisco, San Francisco, CA 94143-0520, USA.
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24
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Deng Y, Chang S. Role of telomeres and telomerase in genomic instability, senescence and cancer. J Transl Med 2007; 87:1071-6. [PMID: 17767195 DOI: 10.1038/labinvest.3700673] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Telomeres are ribonucleoprotein structures that protect the end of linear chromosomes from recognition as DNA double-stranded breaks and activation of a DNA damage response. Telomere-associated proteins also regulate telomerase, the protein responsible for maintaining telomere length. Loss of telomere function results from either alteration in the capping function at telomeres, or from progressive loss of telomeric repeats necessary to maintain proper telomeric structure. Dysfunctional telomeres activate p53 to initiate cellular senescence or apoptosis to suppress tumorigenesis. However, in the absence of p53, telomere dysfunction is an important mechanism to generate chromosomal instability commonly found in human carcinomas. Telomerase is expressed in the majority of human cancers, making it an attractive therapeutic target. Emerging anti-telomerase therapies that are currently in clinical trials might prove useful against some forms of human cancers.
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Affiliation(s)
- Yibin Deng
- Department of Cancer Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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25
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Glanz C, Rebetz J, Stewénius Y, Persson A, Englund E, Mandahl N, Mertens F, Salford LG, Widegren B, Fan X, Gisselsson D. Genetic intratumour heterogeneity in high-grade brain tumours is associated with telomere-dependent mitotic instability. Neuropathol Appl Neurobiol 2007; 33:440-54. [PMID: 17617873 DOI: 10.1111/j.1365-2990.2007.00832.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Glioblastoma multiforme (GBM) and other high-grade brain tumours are typically characterized by complex chromosome abnormalities and extensive intratumour cytogenetic heterogeneity. The mechanisms behind this diversity have been little explored. In this study, we analysed the pattern of chromosome segregation at mitosis in 20 brain tumours. We found an abnormal segregation of chromatids at mitosis through anaphase bridging (10-25% of anaphase cells) in all 10 GBMs. Anaphase bridging was also found in two medulloblastomas (7-15%), one anaplastic astrocytoma (17%) and one oligodendroglioma (6%). These tumours showed a relatively high degree of cytogenetic complexity and heterogeneity. In contrast, cell division abnormalities were not found in low-grade brain tumours with less complex karyotypes, including two pilocytic astrocytomas and two ependymomas. Further analysis of two GBMs by fluorescence in situ hybridization with telomeric repeat probes revealed excessive shortening of TTAGGG repeats, indicating dysfunctional protection of chromosome ends. In xenografts established from these GBMs, there was a gradual reduction in cytogenetic heterogeneity through successive passages as the proportion of abnormally short telomeres was reduced and the frequency of anaphase bridges decreased from >25% to 0. However, bridging could be reintroduced in late-passage xenograft cells by pharmacological induction of telomere shortening, using a small-molecule telomerase inhibitor. Telomere-dependent abnormal segregation of chromosomes at mitosis is thus a common phenomenon in high-grade brain tumours and may be one important factor behind cytogenetic intratumour diversity in GBM.
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Affiliation(s)
- C Glanz
- The Rausing Laboratory, Division of Neurosurgery, Lund University Hospital, Lund, Sweden
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26
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Jackson SR, Zhu CH, Paulson V, Watkins L, Dikmen ZG, Gryaznov SM, Wright WE, Shay JW. Antiadhesive effects of GRN163L--an oligonucleotide N3'->P5' thio-phosphoramidate targeting telomerase. Cancer Res 2007; 67:1121-9. [PMID: 17283146 DOI: 10.1158/0008-5472.can-06-2306] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We determined previously that a novel human telomerase RNA (hTR) antagonist, GRN163L, inhibited the tumorigenic potential of A549-luciferase (A549-luc) lung cancer cells in vitro and in vivo. Further studies revealed that A549-luc cells were also morphologically altered by GRN163L. A549-luc cells treated before cell attachment with a single dose of GRN163L only weakly attached to the substrate and remained rounded, whereas control mismatch-treated cells exhibited typical epitheloid appearance and adhesion properties. These morphologic changes were independent of hTR expression and telomerase inhibition and were unrelated to telomere length. This effect is dependent on the molecular properties of the lipid moiety, the phosphorothioate backbone, and the presence of triplet-G sequences within the GRN163L structure. Altered adhesion was manifested by a 50% reduction in rapid cellular attachment and a 3-fold decrease in total cell spreading surface area. Administration of a single dose of GRN163L (15 mg/kg) at the time of cell inoculation, using an in vivo model of lung cancer metastasis, resulted in significant reductions in tumor burden at days 13, 20, and 27 of tumor progression. Thus, the potent antimetastatic effects of GRN163L may be related, in part, to the antiadhesive effects of this novel cancer therapeutic conferred via specific structural determinants and that these effects are independent of telomerase inhibition or telomere shortening.
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Affiliation(s)
- Shalmica R Jackson
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
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27
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Hochreiter AE, Xiao H, Goldblatt EM, Gryaznov SM, Miller KD, Badve S, Sledge GW, Herbert BS. Telomerase template antagonist GRN163L disrupts telomere maintenance, tumor growth, and metastasis of breast cancer. Clin Cancer Res 2006; 12:3184-92. [PMID: 16707619 DOI: 10.1158/1078-0432.ccr-05-2760] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE Maintenance of telomeres by telomerase is critical for the continuing proliferation of most advanced cancer cells. Telomerase activity has been detected in the vast majority of cancer cells but not most normal cells, making the enzyme an attractive target for anticancer therapy. The aim of this study was to address the breast cancer translational potential of the novel telomerase inhibitor, GRN163L. EXPERIMENTAL DESIGN In the present study, we investigated the effects of GRN163L treatment on a panel of breast cancer cells representing different tumor subtypes with varying genetic backgrounds, including ER+, ER-, HER2+, BRCA1 mutant breast tumor cells as well as doxorubicin-resistant cancer cells. To investigate the in vivo effects of GRN163L, we employed a breast cancer xenograft and metastasis model that simulates a clinical situation in which a patient arrives with a primary tumor that may be then treated or surgically removed. RESULTS GRN163L effectively inhibited telomerase activity in a dose-dependent fashion in all breast cancer cell lines resulting in progressive telomere shortening. A mismatch control oligonucleotide showed no effect on telomerase activity and GRN163L did not significantly affect telomere shortening in normal human mammary epithelial cells or in endothelial cells. Breast cancer cells that exhibited telomerase inhibition also exhibited significant reduction in colony formation and tumorigenicity. Furthermore, GRN163L suppressed tumor growth and lung metastases (P = 0.017) of MDA-MB-231 cells in vivo after 4 weeks of treatment. CONCLUSIONS These results show in vivo effectiveness of GRN163L in breast cancer and support its promising clinical potential for breast cancer treatment.
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MESH Headings
- Adenocarcinoma/drug therapy
- Adenocarcinoma/genetics
- Adenocarcinoma/pathology
- Animals
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Carcinoma, Ductal, Breast/drug therapy
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/pathology
- Dose-Response Relationship, Drug
- Female
- Genes, BRCA1
- Humans
- Lung Neoplasms/prevention & control
- Lung Neoplasms/secondary
- Mice
- Mice, Nude
- Oligonucleotides
- Oligopeptides/pharmacology
- Receptor, ErbB-2/genetics
- Receptors, Estrogen/genetics
- Telomerase/antagonists & inhibitors
- Telomere/ultrastructure
- Transplantation, Heterologous
- Tumor Cells, Cultured
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Affiliation(s)
- Amelia E Hochreiter
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202-5251, USA
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28
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Olaussen KA, Dubrana K, Domont J, Spano JP, Sabatier L, Soria JC. Telomeres and telomerase as targets for anticancer drug development. Crit Rev Oncol Hematol 2006; 57:191-214. [PMID: 16469501 DOI: 10.1016/j.critrevonc.2005.08.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 08/10/2005] [Accepted: 08/11/2005] [Indexed: 12/15/2022] Open
Abstract
In most human cancers, the telomere erosion problem has been bypassed through the activation of a telomere maintenance system (usually activation of telomerase). Therefore, telomere and telomerase are attractive targets for anti-cancer therapeutic interventions. Here, we review a large panel of strategies that have been explored to date, from small inhibitors of the catalytic sub-unit of telomerase to anti-telomerase immunotherapy and gene therapy. The many positive results that are reported from anti-telomere/telomerase assays suggest a prudent optimism for a possible clinical application in a close future. However, we discuss some of the main limits for these approaches of antitumour drug development and why significant work remains before a clinically useful drug can be proposed to patients.
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Affiliation(s)
- Ken André Olaussen
- Laboratory of Radiobiology and Oncology, DSV/DRR/LRO, CEA, Fontenay aux Roses, France
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29
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Pallini R, Sorrentino A, Pierconti F, Maggiano N, Faggi R, Montano N, Maira G, Larocca LM, Levi A, Falchetti ML. Telomerase inhibition by stable RNA interference impairs tumor growth and angiogenesis in glioblastoma xenografts. Int J Cancer 2006; 118:2158-67. [PMID: 16331616 DOI: 10.1002/ijc.21613] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Telomerase is highly expressed in advanced stages of most cancers where it allows the clonal expansion of transformed cells by counteracting telomere erosion. Telomerase may also contribute to tumor progression through still undefined cell growth-promoting functions. Here, we inhibited telomerase activity in 2 human glioblastoma (GBM) cell lines, TB10 and U87MG, by targeting the catalytic subunit, hTERT, via stable RNA interference (RNAi). Although the reduction in telomerase activity had no effect on GBM cell growth in vitro, the development of tumors in subcutaneously and intracranially grafted nude mice was significantly inhibited by antitelomerase RNAi. The in vivo effect was observed within a relatively small number of population doublings, suggesting that telomerase inhibition may hinder cancer cell growth in vivo prior to a substantial shortening of telomere length. Tumor xenografts that arose from telomerase-inhibited GBM cells also showed a less-malignant phenotype due both to the absence of massive necrosis and to reduced angiogenesis.
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Affiliation(s)
- Roberto Pallini
- Institute of Neurosurgery, Catholic University School of Medicine, Rome, Italy.
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Dikmen ZG, Gellert GC, Jackson S, Gryaznov S, Tressler R, Dogan P, Wright WE, Shay JW. In vivo inhibition of lung cancer by GRN163L: a novel human telomerase inhibitor. Cancer Res 2005; 65:7866-73. [PMID: 16140956 DOI: 10.1158/0008-5472.can-05-1215] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Differential regulation of telomerase activity in normal and tumor cells provides a rationale for the design of new classes of telomerase inhibitors. The telomerase enzyme complex presents multiple potential sites for the development of inhibitors. GRN163L, a telomerase enzyme antagonist, is a lipid-modified 13-mer oligonucleotide N3' --> P5'-thio-phosphoramidate, complementary to the template region of telomerase RNA (hTR). We evaluated both the in vitro and in vivo effects of GRN163L using A549-luciferase (A549-Luc) human lung cancer cells expressing a luciferase reporter. GRN163L (1 micromol/L) effectively inhibits telomerase activity of A549-Luc cells, resulting in progressive telomere shortening. GRN163L treatment also reduces colony formation in soft agar assays. Surprisingly, after only 1 week of treatment with GRN163L, A549-Luc cells were unable to form robust colonies in the clonal efficiency assay, whereas the mismatch control compound had no effect. Finally, we show that in vivo treatment with GRN163L is effective in preventing lung metastases in xenograft animal models. These in vitro and in vivo data support the development of GRN163L as a therapeutic for the treatment of cancer.
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Affiliation(s)
- Z Gunnur Dikmen
- University of Hacettepe, Faculty of Medicine, Department of Biochemistry, Ankara, Turkey
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Djojosubroto MW, Chin AC, Go N, Schaetzlein S, Manns MP, Gryaznov S, Harley CB, Rudolph KL. Telomerase antagonists GRN163 and GRN163L inhibit tumor growth and increase chemosensitivity of human hepatoma. Hepatology 2005; 42:1127-36. [PMID: 16114043 DOI: 10.1002/hep.20822] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Most cancer cells have an immortal growth capacity as a consequence of telomerase reactivation. Inhibition of this enzyme leads to increased telomere dysfunction, which limits the proliferative capacity of tumor cells; thus, telomerase inhibition represents a potentially safe and universal target for cancer treatment. We evaluated the potential of two thio-phosphoramidate oligonucleotide inhibitors of telomerase, GRN163 and GRN163L, as drug candidates for the treatment of human hepatoma. GRN163 and GRN163L were tested in preclinical studies using systemic administration to treat flank xenografts of different human hepatoma cell lines (Hep3B and Huh7) in nude mice. The studies showed that both GRN163 and GRN163L inhibited telomerase activity and tumor cell growth in a dose-dependent manner in vitro and in vivo. The potency and efficacy of the lipid-conjugated antagonist, GRN163L, was superior to the nonlipidated parent compound, GRN163. Impaired tumor growth in vivo was associated with critical telomere shortening, induction of telomere dysfunction, reduced rate of cell proliferation, and increased apoptosis in the treatment groups. In vitro, GRN163L administration led to higher prevalence of chromosomal telomere-free ends and DNA damage foci in both hepatoma cell lines. In addition, in vitro chemosensitivity assay showed that pretreatment with GRN163L increased doxorubicin sensitivity of Hep3B. In conclusion, our data support the development of GRN163L, a novel lipidated conjugate of the telomerase inhibitor GRN163, for systemic treatment of human hepatoma. In addition to limiting the proliferative capacity of hepatoma, GRN163L might also increase the sensitivity of this tumor type to conventional chemotherapy.
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Affiliation(s)
- Meta W Djojosubroto
- Department of Gastroenterology, Hepatology, and Endocrinology, Medical School Hannover, Hannover, Germany
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Herbert BS, Gellert GC, Hochreiter A, Pongracz K, Wright WE, Zielinska D, Chin AC, Harley CB, Shay JW, Gryaznov SM. Lipid modification of GRN163, an N3'-->P5' thio-phosphoramidate oligonucleotide, enhances the potency of telomerase inhibition. Oncogene 2005; 24:5262-8. [PMID: 15940257 DOI: 10.1038/sj.onc.1208760] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The vast majority of human cancers express telomerase activity, while most human somatic cells do not have detectable telomerase activity. Since telomerase plays a critical role in cell immortality, it is an attractive target for a selective cancer therapy. Oligonucleotides complementary to the RNA template region of human telomerase (hTR) have been shown to be effective inhibitors of telomerase and, subsequently, cancer cell growth in vitro. We show here that a lipid-modified N3'-->P5' thio-phosphoramidate oligonucleotide (GRN163L) inhibits telomerase more potently than its parental nonconjugated thio-phosphoramidate sequence (GRN163). Cells were treated with both the first- (GRN163) and second-generation (GRN163L) oligonucleotides, including a mismatch control, with or without a transfection enhancer reagent. GRN163L inhibited telomerase activity effectively in a dose-dependent manner, even without the use of a transfection reagent. The IC50 values for GRN163 in various cell lines were on average sevenfold higher than for GRN163L. GRN163L inhibition of telomerase activity resulted in a more rapid loss of telomeres and cell growth than GRN163. This report is the first to show that lipid modification enhanced the potency of the novel GRN163 telomerase inhibitor. These results suggest that the lipid-conjugated thio-phosphoramidates could be important for improved pharmacodynamics of telomerase inhibitors in cancer therapy.
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Affiliation(s)
- Brittney-Shea Herbert
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9039, USA.
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Kelland LR. Overcoming the immortality of tumour cells by telomere and telomerase based cancer therapeutics – current status and future prospects. Eur J Cancer 2005; 41:971-9. [PMID: 15862745 DOI: 10.1016/j.ejca.2004.11.024] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2004] [Accepted: 11/24/2004] [Indexed: 10/25/2022]
Abstract
A key property of malignant tumours is their immortality or limitless replicative potential. Cell replication is associated with the maintenance of telomeres and in the great majority of cases, through the reactivation of the reverse transcriptase telomerase. Targeting the telomere/telomerase machinery offers a novel and potentially broad-spectrum anticancer therapeutic strategy since telomerase is constitutively overexpressed in the vast majority of human cancers. Telomeres are also critically short in most tumours compared to normal tissues. Strategies that exploit these differences include the direct targeting of components of telomerase: the protein component hTERT or RNA component hTR. Examples of such agents include the small molecule hTERT inhibitor BIBR1532 and GRN163L, a thio-phosphoramidate oligonucleotide targeting the template region of hTR as a "template antagonist". Anti-tumour effects have been observed in both cell lines and, especially for GRN163L, in xenografted human tumours in mice. Effects, however, are largely dependent upon initial telomere length, which can result in a substantial lag before antitumour activity is observed in tumours possessing relatively long telomeres. An alternative approach is to target the telomere itself (Telomere Targeting Agents, TTAs). Several classes of small molecules have been described that induce the G-rich single-stranded overhang of telomeric DNA to fold into 4-stranded G-quadruplex structures. Such folding is incompatible with telomerase function and may induce rapid telomere uncapping. These molecules have shown potent telomerase inhibition in nanomolar concentrations in vitro and the rapid induction of senescence in cancer cells. The trisubstituted acridine based TTA, BRACO19, has demonstrated single agent activity against human tumour xenografts with anti-tumour effects apparent from only 7 days of treatment. In the near future, it is expected that lead examples from both the direct telomerase targeted agents (e.g., GRN163L) and from the distinct class of those targeting telomeres (e.g., AS1410 based on BRACO19) will enter Phase I clinical trial where clinical benefit from this class of novel drugs will be determined.
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Affiliation(s)
- Lloyd R Kelland
- Antisoma Research Laboratories, St. Georges Hospital Medical School, Cranmer Terrace, London SW17 OQS, UK.
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