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En A, Takemoto K, Yamakami Y, Nakabayashi K, Fujii M. Upregulated expression of lamin B receptor increases cell proliferation and suppresses genomic instability: implications for cellular immortalization. FEBS J 2024. [PMID: 38462947 DOI: 10.1111/febs.17113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 01/04/2024] [Accepted: 02/28/2024] [Indexed: 03/12/2024]
Abstract
Mammalian somatic cells undergo terminal proliferation arrest after a limited number of cell divisions, a phenomenon termed cellular senescence. However, cells acquire the ability to proliferate infinitely (cellular immortalization) through multiple genetic alterations. Inactivation of tumor suppressor genes such as p53, RB and p16 is important for cellular immortalization, although additional molecular alterations are required for cellular immortalization to occur. Here, we aimed to gain insights into these molecular alterations. Given that cellular immortalization is the escape of cells from cellular senescence, genes that regulate cellular senescence are likely to be involved in cellular immortalization. Because senescent cells show altered heterochromatin organization, we investigated the implications of lamin A/C, lamin B1 and lamin B receptor (LBR), which regulate heterochromatin organization, in cellular immortalization. We employed human immortalized cell lines, KMST-6 and SUSM-1, and found that expression of LBR was upregulated upon cellular immortalization and downregulated upon cellular senescence. In addition, knockdown of LBR induced cellular senescence with altered chromatin configuration. Additionally, enforced expression of LBR increased cell proliferation likely through suppression of genome instability in human primary fibroblasts that expressed the simian virus 40 large T antigen (TAg), which inactivates p53 and RB. Furthermore, expression of TAg or knockdown of p53 led to upregulated LBR expression. These observations suggested that expression of LBR might be upregulated to suppress genome instability in TAg-expressing cells, and, consequently, its upregulated expression assisted the proliferation of TAg-expressing cells (i.e. p53/RB-defective cells). Our findings suggest a crucial role for LBR in the process of cellular immortalization.
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Affiliation(s)
- Atsuki En
- Graduate School of Nanobioscience, Yokohama City University, Japan
| | - Kentaro Takemoto
- Graduate School of Nanobioscience, Yokohama City University, Japan
| | - Yoshimi Yamakami
- Graduate School of Nanobioscience, Yokohama City University, Japan
| | - Kazuhiko Nakabayashi
- Department of Maternal-Fetal Biology, National Center for Child Health and Development, Tokyo, Japan
| | - Michihiko Fujii
- Graduate School of Nanobioscience, Yokohama City University, Japan
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2
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Toubiana S, Tzur-Gilat A, Selig S. Epigenetic Characteristics of Human Subtelomeres Vary in Cells Utilizing the Alternative Lengthening of Telomeres (ALT) Pathway. Life (Basel) 2021; 11:life11040278. [PMID: 33810393 PMCID: PMC8065733 DOI: 10.3390/life11040278] [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: 03/01/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 12/26/2022] Open
Abstract
Most human cancers circumvent senescence by activating a telomere length maintenance mechanism, most commonly involving telomerase activation. A minority of cancers utilize the recombination-based alternative lengthening of telomeres (ALT) pathway. The exact requirements for unleashing normally repressed recombination at telomeres are yet unclear. Epigenetic modifications at telomeric regions were suggested to be pivotal for activating ALT; however, conflicting data exist regarding their exact nature and necessity. To uncover common ALT-positive epigenetic characteristics, we performed a comprehensive analysis of subtelomeric DNA methylation, histone modifications, and TERRA expression in several ALT-positive and ALT-negative cell lines. We found that subtelomeric DNA methylation does not differentiate between the ALT-positive and ALT-negative groups, and most of the analyzed subtelomeres within each group do not share common DNA methylation patterns. Additionally, similar TERRA levels were measured in the ALT-positive and ALT-negative groups, and TERRA levels varied significantly among the members of the ALT-positive group. Subtelomeric H3K4 and H3K9 trimethylation also differed significantly between samples in the ALT-positive group. Our findings do not support a common route by which epigenetic modifications activate telomeric recombination in ALT-positive cells, and thus, different therapeutic approaches will be necessary to overcome ALT-dependent cellular immortalization.
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Affiliation(s)
- Shir Toubiana
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine and Research Institute, Technion, Haifa 31096, Israel; (S.T.); (A.T.-G.)
| | - Aya Tzur-Gilat
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine and Research Institute, Technion, Haifa 31096, Israel; (S.T.); (A.T.-G.)
| | - Sara Selig
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine and Research Institute, Technion, Haifa 31096, Israel; (S.T.); (A.T.-G.)
- Laboratory of Molecular Medicine, Rambam Health Care Campus, Haifa 31096, Israel
- Correspondence:
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3
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Romaniuk A, Paszel-Jaworska A, Totoń E, Lisiak N, Hołysz H, Królak A, Grodecka-Gazdecka S, Rubiś B. The non-canonical functions of telomerase: to turn off or not to turn off. Mol Biol Rep 2018; 46:1401-1411. [PMID: 30448892 DOI: 10.1007/s11033-018-4496-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 11/12/2018] [Indexed: 12/19/2022]
Abstract
Telomerase is perceived as an immortality enzyme that enables passing the Hayflick limit. Its main function is telomere restoration but only in a limited group of cells, including cancer cells. Since it is found in a vast majority of cancer cells, it became a natural target for cancer therapy. However, it has much more functions than just altering the metabolism of telomeres-it also reveals numerous so-called non-canonical functions. Thus, a question arises whether it is always beneficial to turn it off when planning a cancer strategy and considering potential side effects? The purpose of this review is to discuss some of the recent discoveries about telomere-independent functions of telomerase in the context of cancer therapy and potential side effects.
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Affiliation(s)
- Aleksandra Romaniuk
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Anna Paszel-Jaworska
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Ewa Totoń
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Natalia Lisiak
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Hanna Hołysz
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Anna Królak
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | | | - Błażej Rubiś
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland.
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4
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Wadhwa R, Ryu J, Ahn HM, Saxena N, Chaudhary A, Yun CO, Kaul SC. Functional significance of point mutations in stress chaperone mortalin and their relevance to Parkinson disease. J Biol Chem 2015; 290:8447-56. [PMID: 25645922 DOI: 10.1074/jbc.m114.627463] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mortalin/mtHsp70/Grp75 (mot-2), a heat shock protein 70 family member, is an essential chaperone, enriched in cancers, and has been shown to possess pro-proliferative and anti-apoptosis functions. An allelic form of mouse mortalin (mot-1) that differs by two amino acids, M618V and G624R, in the C terminus substrate-binding domain has been reported. Furthermore, genome sequencing of mortalin from Parkinson disease patients identified two missense mutants, R126W and P509S. In the present study, we investigated the significance of these mutations in survival, proliferation, and oxidative stress tolerance in human cells. Using mot-1 and mot-2 recombinant proteins and specific antibodies, we performed screening to find their binding proteins and then identified ribosomal protein L-7 (RPL-7) and elongation factor-1 α (EF-1α), which differentially bind to mot-1 and mot-2, respectively. We demonstrate that mot-1, R126W, or P509S mutant (i) lacks mot-2 functions involved in carcinogenesis, such as p53 inactivation and hTERT/hnRNP-K (heterogeneous nuclear ribonucleoprotein K) activation; (ii) causes increased level of endogenous oxidative stress; (iii) results in decreased tolerance of cells to exogenous oxidative stress; and (iv) shows differential binding and impact on the RPL-7 and EF-1α proteins. These factors may mediate the transformation of longevity/pro-proliferative function of mot-2 to the premature aging/anti-proliferative effect of mutants, and hence may have significance in cellular aging, Parkinson disease pathology, and prognosis.
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Affiliation(s)
- Renu Wadhwa
- From the Cell Proliferation Research Group and Department of Biotechnology (DBT, India)-National Institute of Advanced Industrial Science and Technology (AIST, Japan) International Laboratory for Advanced Biomedicine (DAILAB), Tsukuba, Ibaraki 305-8562, Japan and
| | - Jihoon Ryu
- From the Cell Proliferation Research Group and Department of Biotechnology (DBT, India)-National Institute of Advanced Industrial Science and Technology (AIST, Japan) International Laboratory for Advanced Biomedicine (DAILAB), Tsukuba, Ibaraki 305-8562, Japan and the Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 133-791, Korea
| | - Hyo Min Ahn
- From the Cell Proliferation Research Group and Department of Biotechnology (DBT, India)-National Institute of Advanced Industrial Science and Technology (AIST, Japan) International Laboratory for Advanced Biomedicine (DAILAB), Tsukuba, Ibaraki 305-8562, Japan and the Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 133-791, Korea
| | - Nishant Saxena
- From the Cell Proliferation Research Group and Department of Biotechnology (DBT, India)-National Institute of Advanced Industrial Science and Technology (AIST, Japan) International Laboratory for Advanced Biomedicine (DAILAB), Tsukuba, Ibaraki 305-8562, Japan and
| | - Anupama Chaudhary
- From the Cell Proliferation Research Group and Department of Biotechnology (DBT, India)-National Institute of Advanced Industrial Science and Technology (AIST, Japan) International Laboratory for Advanced Biomedicine (DAILAB), Tsukuba, Ibaraki 305-8562, Japan and
| | - Chae-Ok Yun
- the Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsimni-Ro, Seongdong-Gu, Seoul 133-791, Korea
| | - Sunil C Kaul
- From the Cell Proliferation Research Group and Department of Biotechnology (DBT, India)-National Institute of Advanced Industrial Science and Technology (AIST, Japan) International Laboratory for Advanced Biomedicine (DAILAB), Tsukuba, Ibaraki 305-8562, Japan and
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Saxena N, Katiyar S, Liu Y, Grover A, Gao R, Sundar D, Kaul S, Wadhwa R. Molecular interactions of Bcl-2 and Bcl-xL with mortalin: identification and functional characterization. Biosci Rep 2013; 33:e00073. [PMID: 24050266 PMCID: PMC3797589 DOI: 10.1042/bsr20130034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 05/28/2013] [Accepted: 06/03/2013] [Indexed: 11/17/2022] Open
Abstract
Bcl-2 family of proteins consists of both pro-apoptotic and anti-apoptotic members that control cellular apoptosis. They predominantly reside in the mitochondria and control the release of apoptotic factors from the mitochondria to the cytosol by regulating its membrane potential and opening the PT (permeability transition) pore. Here we report bioinformatics and biochemical evidence to demonstrate the interaction between Bcl-2 and Bcl-xL with a stress chaperone, mortalin. We demonstrate that such interaction results in the abrogation of mortalin-p53 interaction leading to nuclear translocation and transcriptional reactivation of p53 function that results in an induction of senescence in cancer cells.
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Key Words
- bcl-2
- bcl-xl
- interaction
- mortalin
- p53 activation
- senescence
- bad, bcl-2/bcl-xl-antagonist, causing cell death
- bh, bcl-2 homology
- bim, bcl-2-interacting mediator of cell death
- dmem, dulbecco’s modified eagle’s medium
- gfp, green fluorescent protein
- hsp 70, heat-shock protein 70
- ic, immunocomplexes
- md, molecular dynamics
- pbs-t, triton x-100 in pbs
- pt, permeability transition
- ros, reactive oxygen species
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Affiliation(s)
- Nishant Saxena
- *National Institute of Advanced Industrial Science and Technology (AIST), Central 4, 1-1-1 Higashi, Tsukuba Science City 305-8562, Japan
| | - Shashank P. Katiyar
- †Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India
| | - Ye Liu
- *National Institute of Advanced Industrial Science and Technology (AIST), Central 4, 1-1-1 Higashi, Tsukuba Science City 305-8562, Japan
| | - Abhinav Grover
- †Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India
| | - Ran Gao
- *National Institute of Advanced Industrial Science and Technology (AIST), Central 4, 1-1-1 Higashi, Tsukuba Science City 305-8562, Japan
| | - Durai Sundar
- †Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India
| | - Sunil C. Kaul
- *National Institute of Advanced Industrial Science and Technology (AIST), Central 4, 1-1-1 Higashi, Tsukuba Science City 305-8562, Japan
| | - Renu Wadhwa
- *National Institute of Advanced Industrial Science and Technology (AIST), Central 4, 1-1-1 Higashi, Tsukuba Science City 305-8562, Japan
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6
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Vaishnavi K, Saxena N, Shah N, Singh R, Manjunath K, Uthayakumar M, Kanaujia SP, Kaul SC, Sekar K, Wadhwa R. Differential activities of the two closely related withanolides, Withaferin A and Withanone: bioinformatics and experimental evidences. PLoS One 2012; 7:e44419. [PMID: 22973447 PMCID: PMC3433425 DOI: 10.1371/journal.pone.0044419] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 08/07/2012] [Indexed: 12/24/2022] Open
Abstract
Background and Purpose Withanolides are naturally occurring chemical compounds. They are secondary metabolites produced via oxidation of steroids and structurally consist of a steroid-backbone bound to a lactone or its derivatives. They are known to protect plants against herbivores and have medicinal value including anti-inflammation, anti-cancer, adaptogenic and anti-oxidant effects. Withaferin A (Wi-A) and Withanone (Wi-N) are two structurally similar withanolides isolated from Withania somnifera, also known as Ashwagandha in Indian Ayurvedic medicine. Ashwagandha alcoholic leaf extract (i-Extract), rich in Wi-N, was shown to kill cancer cells selectively. Furthermore, the two closely related purified phytochemicals, Wi-A and Wi-N, showed differential activity in normal and cancer human cells in vitro and in vivo. We had earlier identified several genes involved in cytotoxicity of i-Extract in human cancer cells by loss-of-function assays using either siRNA or randomized ribozyme library. Methodology/Principal Findings In the present study, we have employed bioinformatics tools on four genes, i.e., mortalin, p53, p21 and Nrf2, identified by loss-of-function screenings. We examined the docking efficacy of Wi-N and Wi-A to each of the four targets and found that the two closely related phytochemicals have differential binding properties to the selected cellular targets that can potentially instigate differential molecular effects. We validated these findings by undertaking parallel experiments on specific gene responses to either Wi-N or Wi-A in human normal and cancer cells. We demonstrate that Wi-A that binds strongly to the selected targets acts as a strong cytotoxic agent both for normal and cancer cells. Wi-N, on the other hand, has a weak binding to the targets; it showed milder cytotoxicity towards cancer cells and was safe for normal cells. The present molecular docking analyses and experimental evidence revealed important insights to the use of Wi-A and Wi-N for cancer treatment and development of new anti-cancer phytochemical cocktails.
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Affiliation(s)
- Kirti Vaishnavi
- Supercomputer Education and Research Centre, Indian Institute of Science, Bangalore, India
| | - Nishant Saxena
- National Institute of Advanced Industrial Science and Technology (AIST), Central 4, Tsukuba, Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Navjot Shah
- National Institute of Advanced Industrial Science and Technology (AIST), Central 4, Tsukuba, Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Rumani Singh
- National Institute of Advanced Industrial Science and Technology (AIST), Central 4, Tsukuba, Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Kavyashree Manjunath
- Supercomputer Education and Research Centre, Indian Institute of Science, Bangalore, India
| | - M. Uthayakumar
- Supercomputer Education and Research Centre, Indian Institute of Science, Bangalore, India
| | - Shankar P. Kanaujia
- Supercomputer Education and Research Centre, Indian Institute of Science, Bangalore, India
| | - Sunil C. Kaul
- National Institute of Advanced Industrial Science and Technology (AIST), Central 4, Tsukuba, Japan
| | - Kanagaraj Sekar
- Supercomputer Education and Research Centre, Indian Institute of Science, Bangalore, India
- * E-mail: (KS); (RW)
| | - Renu Wadhwa
- National Institute of Advanced Industrial Science and Technology (AIST), Central 4, Tsukuba, Japan
- * E-mail: (KS); (RW)
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7
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Yoo JY, Ryu J, Gao R, Yaguchi T, Kaul SC, Wadhwa R, Yun CO. Tumor suppression by apoptotic and anti-angiogenic effects of mortalin-targeting adeno-oncolytic virus. J Gene Med 2010; 12:586-95. [PMID: 20603860 DOI: 10.1002/jgm.1471] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Adeno-oncolytic (Adon) viruses offer an effective cancer therapeutic tool with several advantages, including wide host cell permeability, high transduction efficiency, safety, tumor selectivity, non-invasiveness, high genetic modifiability and high level of expression of the integrated transgenes. Armed Adon viruses in which the therapeutic efficacy of virus is enhanced by their coupling with cytotoxic, anti-angiogenic or anti-vascular gene products have gained importance because they engage additional mechanisms for tumor cell killing. In the present study, we selected mortalin, a stress chaperone that is tightly involved in human carcinogenesis, constructed a mortalin-targeting Adon (mot-Adon) virus and examined its therapeutic potential both in vitro and in vivo. METHODS Mortalin-targeting plasmid and viral vectors that harbored mortalin-specific small interfering RNA sequences were constructed. The therapeutic value of these vectors was investigated in vitro and in vivo by cell culture and nude mice tumor models. RESULTS We demonstrate that the mot-Adon virus has selective cytotoxicity for human cancer cells in vitro. Retrovirus-mediated overexpression of mortalin protected the cells against mot-Adon virus, confirming that mortalin silencing was the real cause of cancer cell death. Although mortalin overexpression enhanced malignant properties of cancer cells in breast xenograft models, mot-Adon virus elicited an enhanced anti-tumor effect. Immunohistochemical examination of the tumors showed that the mot-Adon virus caused enhanced apoptosis (mediated by reactivation of p53) and suppression of microvessel formation. CONCLUSIONS Mortalin is up-regulated in a large variety of tumors and hence mot-Adon virus is proposed as a candidate cancer therapeutic agent.
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Affiliation(s)
- Ji Young Yoo
- Brain Korea 21 Project for Medical Sciences, Institute for Cancer Research, Yonsei University College of Medicine, Seoul, Korea
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Henson JD, Reddel RR. Assaying and investigating Alternative Lengthening of Telomeres activity in human cells and cancers. FEBS Lett 2010; 584:3800-11. [PMID: 20542034 DOI: 10.1016/j.febslet.2010.06.009] [Citation(s) in RCA: 176] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 06/08/2010] [Indexed: 12/14/2022]
Abstract
Alternative Lengthening of Telomeres (ALT) activity can be deduced from the presence of telomere length maintenance in the absence of telomerase activity. More convenient assays for ALT utilize phenotypic markers of ALT activity, but only a few of these assays are potentially definitive. Here we assess each of the current ALT assays and their implications for understanding the ALT mechanism. We also review the clinical situations where availability of an ALT activity assay would be advantageous. The prevalence of ALT ranges from 25% to 60% in sarcomas and 5% to 15% in carcinomas. Patients with many of these types of ALT[+] tumors have a poor prognosis.
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Affiliation(s)
- Jeremy D Henson
- Children's Medical Research Institute, Sydney, NSW, Australia
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9
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Shah N, Kataria H, Kaul SC, Ishii T, Kaur G, Wadhwa R. Effect of the alcoholic extract of Ashwagandha leaves and its components on proliferation, migration, and differentiation of glioblastoma cells: combinational approach for enhanced differentiation. Cancer Sci 2009; 100:1740-7. [PMID: 19575749 PMCID: PMC11159946 DOI: 10.1111/j.1349-7006.2009.01236.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 05/21/2009] [Accepted: 05/22/2009] [Indexed: 01/26/2023] Open
Abstract
Ashwagandha (Withania somnifera) is widely used in the Indian traditional system of medicine, Ayurveda. Although it is claimed to have a large variety of health-promoting effects, including therapeutic effects on stress and disease, the mechanisms of action have not yet been determined. In the present study, we aimed to investigate the growth inhibition and differentiation potential of the alcoholic extract of Ashwagandha leaves (i-Extract), its different constituents (Withaferin A, Withanone, Withanolide A) and their combinations on glioma (C6 and YKG1) cell lines. Withaferin A, Withanone, Withanolide A and i-Extract markedly inhibited the proliferation of glioma cells in a dose-dependent manner and changed their morphology toward the astrocytic type. Molecular analysis revealed that the i-Extract and some of its components caused enhanced expression of glial fibrillary acidic protein, change in the immunostaining pattern of mortalin from perinuclear to pancytoplasmic, delay in cell migration, and increased expression of neuronal cell adhesion molecules. The data suggest that the i-Extract and its components have the potential to induce senescence-like growth arrest and differentiation in glioma cells. These assays led us to formulate a unique combination formula of i-Extract components that caused enhanced differentiation of glial cells.
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Affiliation(s)
- Navjot Shah
- National Institute of Advanced Industrial Science and Technology, University if Tsukuba, Ibaraki, Japan
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10
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Shiota M, Ikeda Y, Kaul Z, Itadani J, Kaul SC, Wadhwa R. Internalizing Antibody-Based Targeted Gene Delivery for Human Cancer Cells. Hum Gene Ther 2007; 18:1153-60. [DOI: 10.1089/hum.2007.087] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Maki Shiota
- National Institute of Advanced Industrial Science and Technology (ASIT), Tsukuba, Ibaraki 305-8562, Japan
- Department of Chemistry and Biotechnology, School of Engineering, University of Tokyo, Hongo, Tokyo 113-8656, Japan
| | - Yutaka Ikeda
- National Institute of Advanced Industrial Science and Technology (ASIT), Tsukuba, Ibaraki 305-8562, Japan
| | - Zeenia Kaul
- National Institute of Advanced Industrial Science and Technology (ASIT), Tsukuba, Ibaraki 305-8562, Japan
| | - Jun Itadani
- National Institute of Advanced Industrial Science and Technology (ASIT), Tsukuba, Ibaraki 305-8562, Japan
| | - Sunil C. Kaul
- National Institute of Advanced Industrial Science and Technology (ASIT), Tsukuba, Ibaraki 305-8562, Japan
| | - Renu Wadhwa
- National Institute of Advanced Industrial Science and Technology (ASIT), Tsukuba, Ibaraki 305-8562, Japan
- Department of Chemistry and Biotechnology, School of Engineering, University of Tokyo, Hongo, Tokyo 113-8656, Japan
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11
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Kaul Z, Yaguchi T, Chiura HX, Kaul SC, Wadhwa R. Quantum dot-based mortalin staining as a visual assay for detection of induced senescence in cancer cells. Ann N Y Acad Sci 2007; 1100:368-72. [PMID: 17460200 DOI: 10.1196/annals.1395.040] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Quantum dots (QDs) are fluorescent nanocrystals that are emerging as fine alternatives to the conventional organic dyes. They have several advantages including greater photostability and a wider range of excitation-emission wavelengths. By using mortalin staining as a model, we initially demonstrated that the QDs are more stable and provide better resolution in protein imaging in fixed cells. With the help of an internalizing antibody, we generated internalizing QD (i-QD) and demonstrated its inertness to cell replication, structure, and viability. Based on the superior resolution, stability and inertness, we propose the use of QD staining of mortalin as a cell-based visual assay to screen for senescence-inducing drugs, proteins, and siRNAs.
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Affiliation(s)
- Zeenia Kaul
- Research Institute for Cell Engineering, National Institute of Advanced Industrial Science and Technology (AIST), Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305 8562, Japan
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12
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Wadhwa R, Takano S, Kaur K, Aida S, Yaguchi T, Kaul Z, Hirano T, Taira K, Kaul S. Identification and characterization of molecular interactions between mortalin/mtHsp70 and HSP60. Biochem J 2006; 391:185-90. [PMID: 15957980 PMCID: PMC1276915 DOI: 10.1042/bj20050861] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mortalin/mtHsp70 (mitochondrial Hsp70) and HSP60 (heat-shock protein 60) are heat-shock proteins that reside in multiple subcellular compartments, with mitochondria being the predominant one. In the present study, we demonstrate that the two proteins interact both in vivo and in vitro, and that the N-terminal region of mortalin is involved in these interactions. Suppression of HSP60 expression by shRNA (short hairpin RNA) plasmids caused the growth arrest of cancer cells similar to that obtained by suppression of mortalin expression by ribozymes. An overexpression of mortalin, but not of HSP60, extended the in vitro lifespan of normal fibroblasts (TIG-1). Taken together, this study for the first time delineates: (i) molecular interactions of HSP60 with mortalin; (ii) their co- and exclusive localizations in vivo; (iii) their involvement in tumorigenesis; and (iv) their functional distinction in pathways involved in senescence.
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Affiliation(s)
- Renu Wadhwa
- *Gene Function Research Center, National Institute of Advanced Industrial Science & Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan
| | - Syuichi Takano
- †Laboratory of Biochemistry and Molecular Cell Biology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-0934, Japan
| | - Kamaljit Kaur
- *Gene Function Research Center, National Institute of Advanced Industrial Science & Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan
| | - Satoshi Aida
- *Gene Function Research Center, National Institute of Advanced Industrial Science & Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan
| | - Tomoko Yaguchi
- *Gene Function Research Center, National Institute of Advanced Industrial Science & Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan
| | - Zeenia Kaul
- *Gene Function Research Center, National Institute of Advanced Industrial Science & Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan
| | - Takashi Hirano
- ‡Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science & Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Kazunari Taira
- *Gene Function Research Center, National Institute of Advanced Industrial Science & Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan
| | - Sunil C. Kaul
- *Gene Function Research Center, National Institute of Advanced Industrial Science & Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan
- To whom correspondence should be addressed (email )
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13
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Chang S. Modeling aging and cancer in the telomerase knockout mouse. Mutat Res 2005; 576:39-53. [PMID: 15927211 DOI: 10.1016/j.mrfmmm.2004.08.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Revised: 08/12/2004] [Accepted: 08/12/2004] [Indexed: 10/25/2022]
Abstract
The telomerase deficient mouse has been invaluable in providing insights into basic questions pertaining to consequences of telomere dysfunction during aging and cancer in the context of the mammalian organism. Studies using this mouse model have demonstrated that cellular responses to telomere dysfunction are fundamentally conserved in both humans and mice, and that the tight regulation of telomere length and telomerase activity in somatic cells may be important in mediating the balance between aging and cancer. Here, I discuss the use of the telomerase null mouse for understanding the contrasting roles of telomeres and telomerase in organismal aging and cancer.
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Affiliation(s)
- Sandy Chang
- Department of Molecular Genetics, MD Anderson Cancer Center, Houston, TX 77030, USA.
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14
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Jiang WQ, Zhong ZH, Henson JD, Neumann AA, Chang ACM, Reddel RR. Suppression of alternative lengthening of telomeres by Sp100-mediated sequestration of the MRE11/RAD50/NBS1 complex. Mol Cell Biol 2005; 25:2708-21. [PMID: 15767676 PMCID: PMC1061646 DOI: 10.1128/mcb.25.7.2708-2721.2005] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Approximately 10% of cancers overall use alternative lengthening of telomeres (ALT) instead of telomerase to prevent telomere shortening, and ALT is especially common in astrocytomas and various types of sarcomas. The hallmarks of ALT in telomerase-negative cancer cells include a unique pattern of telomere length heterogeneity, rapid changes in individual telomere lengths, and the presence of ALT-associated promyelocytic leukemia bodies (APBs) containing telomeric DNA and proteins involved in telomere binding, DNA replication, and recombination. The ALT mechanism appears to involve recombination-mediated DNA replication, but the molecular details are largely unknown. In telomerase-null Saccharomyces cerevisiae, an analogous survivor mechanism is dependent on the RAD50 gene. We demonstrate here that overexpression of Sp100, a constituent of promyelocytic leukemia nuclear bodies, sequestered the MRE11, RAD50, and NBS1 recombination proteins away from APBs. This resulted in repression of the ALT mechanism, as evidenced by progressive telomere shortening at 121 bp per population doubling, a rate within the range found in telomerase-negative normal cells, suppression of rapid telomere length changes, and suppression of APB formation. Spontaneously generated C-terminally truncated Sp100 that did not sequester the MRE11, RAD50, and NBS1 proteins failed to inhibit ALT. These findings identify for the first time proteins that are required for the ALT mechanism.
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Affiliation(s)
- Wei-Qin Jiang
- Children's Medical Research Institute, 214 Hawkesbury Rd., Westmead, NSW 2145, Australia
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15
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Henson JD, Hannay JA, McCarthy SW, Royds JA, Yeager TR, Robinson RA, Wharton SB, Jellinek DA, Arbuckle SM, Yoo J, Robinson BG, Learoyd DL, Stalley PD, Bonar SF, Yu D, Pollock RE, Reddel RR. A Robust Assay for Alternative Lengthening of Telomeres in Tumors Shows the Significance of Alternative Lengthening of Telomeres in Sarcomas and Astrocytomas. Clin Cancer Res 2005. [DOI: 10.1158/1078-0432.217.11.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Abstract
Purpose and Experimental Design: Telomeres of tumor cells may be maintained by telomerase or by alternative lengthening of telomeres (ALT). The standard ALT assay requires Southern analysis of high molecular weight genomic DNA. We aimed to establish and validate an ALT assay suitable for archived paraffin-embedded tumors and to use it to examine the prevalence and clinical significance of ALT in various types of tumors that are often telomerase negative.
Results: To assay for ALT, we detected ALT-associated promyelocytic leukemia (PML) bodies (APBs) by combined PML immunofluorescence and telomere fluorescence in situ hybridization. APBs are PML nuclear domains containing telomeric DNA and are a known hallmark of ALT in cell lines. The APB assay concurred with the standard ALT assay in 62 of 62 tumors and showed that 35% of 101 soft tissue sarcomas (STS), 47% of 58 osteosarcomas (especially younger patients), 34% of 50 astrocytomas, and 0% of 17 papillary thyroid carcinomas were ALT positive (ALT+). The prevalence of ALT varied greatly among different STS subtypes: malignant fibrous histiocytomas, 77%; leiomyosarcomas, 62%; liposarcomas, 33%; synovial sarcomas, 9%; and rhabdomyosarcomas, 6%. ALT correlated with survival in glioblastoma multiforme and occurred more often in lower-grade astrocytomas, but ALT+ and ALT− sarcomas were equally aggressive in terms of grade and clinical outcome.
Conclusion: The APB assay for ALT is suitable for paraffin-embedded tumors. It showed that a substantial proportion of STS, osteosarcomas, and astrocytomas, but not papillary thyroid carcinomas use ALT. APB positivity correlated strongly with survival of patients with astrocytomas.
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Affiliation(s)
| | | | | | - Janice A. Royds
- 7University of Otago, Dunedin, New Zealand
- 8Royal Hallamshire Hospital, Sheffield, United Kingdom
| | | | | | | | | | | | - Jinyoung Yoo
- 10Department of Pathology, St Vincent's Hospital, Catholic University, Suwon, Kyungkido, South Korea
| | | | | | | | - S. Fiona Bonar
- 5Douglass Hanly Moir Pathology, Sydney, New South Wales, Australia
| | - Dihua Yu
- 6MD Anderson Cancer Center, Houston, Texas
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16
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Abstract
Telomere length may be maintained in cancer cells by telomerase or an alternative lengthening of telomeres (ALT) mechanism. Low levels of telomerase activity have been detected in some normal somatic cells and presumably some types of normal cells also have low levels of an ALT-like activity. It is hypothesized here that inherited abnormalities of these and other aspects of telomere maintenance may contribute to cancer and ageing. The telomere length maintenance mechanisms are similar in that activation of each is associated with immortalization. They may also confer other properties on cancer cells, however, and the nature of these additional properties may be different for telomerase and ALT. It is expected that these similarities and differences will have implications for prognosis and treatment.
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17
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Chang S, Khoo CM, Naylor ML, Maser RS, DePinho RA. Telomere-based crisis: functional differences between telomerase activation and ALT in tumor progression. Genes Dev 2003; 17:88-100. [PMID: 12514102 PMCID: PMC195968 DOI: 10.1101/gad.1029903] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Telomerase activation is a common feature of most advanced human cancers and is postulated to restore genomic stability to a level permissive for cell viability and tumor progression. Here, we used genetically defined transformed mouse embryonic fibroblast (MEF) cultures derived from late generation mTerc(-/-) Ink4a/Arf(-/-) mice to explore more directly how telomere-based crisis relates to the evolution of cancer cell genomes and to tumor biology. An exhaustive serial analysis of cytogenetic profiles over extensive passage in culture revealed that the emergence of chromosomal fusions (including dicentrics) coincided with onset of deletions and complex nonreciprocal translocations (NRTs), whereas mTerc-transduced cultures maintained intact chromosomes and stable genomes. Despite a high degree of telomere dysfunction and genomic instability, transformed late passage mTerc(-/-) Ink4a/Arf(-/-) cultures retained the capacity to form subcutaneous tumors in immunocompromised mice. However, even moderate levels of telomere dysfunction completely abrogated the capacity of these cells to form lung metastases after tail-vein injection, whereas mTerc reconstitution alone conferred robust metastatic activity in these cells. Finally, serial subcutaneous tumor formation using late passage transformed mTerc(-/-) Ink4a/Arf(-/-) cultures revealed clear evidence of telomerase-independent alternative lengthening of telomeres (ALT). Significantly, despite a marked increase in telomere reserve, cells derived from the ALT+ subcutaneous tumors were unable to generate lung metastases, indicating in vivo functional differences in these principal mechanisms of telomere maintenance. Together, these results are consistent with the model that although telomere dysfunction provokes chromosomal aberrations that initiate carcinogenesis, telomerase-mediated telomere maintenance enables such initiated cells to efficiently achieve a fully malignant endpoint, including metastasis.
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Affiliation(s)
- Sandy Chang
- Department of Medical Oncology, Dana Farber Cancer Institute, Boston, Massachusetts 02115, USA
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18
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Sawada T, Yamada O, Yoshimura N, Hatori K, Fuchinoue S, Teraoka S. Xenoantigen, an alphaGal epitope-expression construct driven by the hTERT-promoter, specifically kills human pancreatic cancer cell line. Cancer Cell Int 2002; 2:14. [PMID: 12392598 PMCID: PMC140132 DOI: 10.1186/1475-2867-2-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2002] [Accepted: 10/03/2002] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND: We previously reported the usefulness of the alphaGal epitope as a target molecule for gene therapy against cancer. To induce cancer cell specific transcription of the alphaGal epitope, an expression vector which synthesizes the alphaGal epitope under the control of a promoter region of the human telomerase reverse transcriptase (hTERT), NK7, was constructed. METHODS: NK7 was transfected into a human pancreatic carcinoma cell line, MIA cells, and telomerase-negative SUSM-1 cells served controls. Expression of the alphaGal epitope was confirmed by flow cytometry using IB4 lectin. The susceptibility of transfected MIA cells to human natural antibodies, was examined using a complement-dependent cytotoxic cross-match test (CDC) and a flow cytometry using annexin V. RESULTS: The alphaGal epitope expression was detected only on the cell surfaces of NK7-transfected MIA cells, i.e., not on naive MIA cells or telomerase negative SUSM-1 cells. The CDC results indicated that MIA cells transfected with NK7 are susceptible to human natural antibody-mediated cell killing, and the differences, as compared to NK-7 transfected telomerase negative SUSM-1 cells or telomerase positive naïve MIA cells, were statistically significant. The flow cytometry using annexin V showed a higher number of the apoptotic cells in NK-7 transfected MIA cells than in naïve MIA cells. CONCLUSIONS: The results suggest that alphaGal epitope-expression, under the control of the hTERT-promoter, may be useful in cancer specific gene therapy.
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Affiliation(s)
- Tokihiko Sawada
- Tokyo Women's Medical University, Kidney Center, Department of Surgery 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Osamu Yamada
- Tokyo Women's Medical University, Medical Research Institute 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Naoko Yoshimura
- Tokyo Women's Medical University, Kidney Center, Department of Surgery 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Keiko Hatori
- Tokyo Women's Medical University, Kidney Center, Department of Surgery 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Shohei Fuchinoue
- Tokyo Women's Medical University, Kidney Center, Department of Surgery 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Satoshi Teraoka
- Tokyo Women's Medical University, Kidney Center, Department of Surgery 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
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19
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Suzuki T, Fujii M, Ayusawa D. Demethylation of classical satellite 2 and 3 DNA with chromosomal instability in senescent human fibroblasts. Exp Gerontol 2002; 37:1005-14. [PMID: 12213551 DOI: 10.1016/s0531-5565(02)00061-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Demethylation of genomic 5-methylcytosine is reported in aged human tissues and senesced human cells, although it is not understood to what extent this phenomenon contributes to replicative senescence. We examined methylation status of satellite 2 and 3 sequences during passages of normal human fibroblasts. These sequences are abundant in the juxtacentromeric heterochromatin of human chromosomes 1, 9 and 16, and heavily methylated in tissues of normal individuals. The decrease in DNA methylation level was two times faster in satellite 3 DNA than in satellite 2 and total DNA. Then we monitored appearance of micronuclei during the passages since they are indicative of heterochromatin decondensation or chromosome breakage. Concomitant with the DNA demethylation, micronuclei containing the heterochromatin of chromosomes 1, 9 or 16, appeared specifically. These results suggest that demethylation of heterochromatin has a role in replicative senescence through chromosome instability.
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Affiliation(s)
- Toshikazu Suzuki
- Kihara Institute for Biological Research, Yokohama City University, Maioka-cho 641-12, Totsuka-ku, Yokohama 244-0813, Japan
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20
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Arai Y, Shigeeda N, Uchida M, Tsutsui T. Loss of heterozygosity on chromosome 7q in in vitro-immortalized human oral keratinocyte cell lines. Arch Oral Biol 2002; 47:585-9. [PMID: 12221015 DOI: 10.1016/s0003-9969(02)00048-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Loss of heterozygosity in two in vitro-immortalized human oral keratinocyte cell lines was analysed by polymerase chain reaction using 42 polymorphic microsatellite markers on chromosomes 4, 6, 7 and 15. These chromosomes are regarded as candidates for harbouring genes involved in the immortalization of human cells or tumour-suppressor genes in several tumours, including oral cancers, and karyotypic analysis has revealed that both cell lines have non-random alterations in these chromosomes. No allele losses were detected at any informative loci on chromosomes 4 and 6 in the cell lines, including genomic regions adjacent to putative human tumour-suppressor genes and putative senescence genes. When analysed for loss of heterozygosity on chromosomes 7 and 15, allele losses common to both cell lines were detected in the regions at 7q11.2, 7q21.1-21.3 and 7q31.1. High frequencies of loss of heterozygosity on chromosome 7q in at least two distinct regions, particularly centred around 7q31, are observed in a variety of tumours, including oral squamous-cell carcinoma, suggesting that multiple genes involved in immortalization of these cell lines might be present on chromosome 7q.
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MESH Headings
- Cell Line, Transformed/physiology
- Cell Line, Transformed/virology
- Chromosomes, Human, Pair 15/genetics
- Chromosomes, Human, Pair 4/genetics
- Chromosomes, Human, Pair 6/genetics
- Chromosomes, Human, Pair 7/genetics
- Humans
- Keratinocytes/physiology
- Loss of Heterozygosity
- Microsatellite Repeats
- Mouth Mucosa/cytology
- Polymerase Chain Reaction
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Affiliation(s)
- Yasuhito Arai
- Oral and Maxillofacial Surgery, The Nippon Dental University Hospital at Tokyo, 2-3-16 Fujimi, Chiyoda-ku, Tokyo 102-8158, Japan
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21
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Abstract
Cellular senescence or replicative senescence is a state of irreversible growth arrest that somatic cells enter as a result of replicative exhaustion. This can be mimicked by culture manipulations such as Ras oncogene overexpression or treatment with various agents such as sodium butyrate and 5-azacytidine. It is believed that cellular senescence is one of the protective mechanisms against tumor formation. Genetic analyses of cellular senescence have revealed that it is dominant over immortality because whole cell fusion of normal with immortal cells yields hybrids with limited division potential. Only four complementation groups for indefinite division have been identified from extensive studies fusing different immortal human cell lines with each other. The senescence-related genes for three of the complementation groups B-D have been identified on human chromosomes 4, 1, and 7, respectively, by microcell-mediated chromosome transfer, though the existence of senescence-related genes on other chromosomes has been suggested. MORF4 was cloned as the senescence-related gene on human chromosome 4 and is a member of a new gene family, which has multiple transcription factor-like motifs. This gene family may affect cell division by modulating gene expression. Study of this novel gene family should lead to new insights regarding the mechanisms and function of cellular senescence in aging and immortalization.
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Affiliation(s)
- Kaoru Tominaga
- Sam and Ann Barshop Center for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, STCBM, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA
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22
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Henson JD, Neumann AA, Yeager TR, Reddel RR. Alternative lengthening of telomeres in mammalian cells. Oncogene 2002; 21:598-610. [PMID: 11850785 DOI: 10.1038/sj.onc.1205058] [Citation(s) in RCA: 458] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Some immortalized mammalian cell lines and tumors maintain or increase the overall length of their telomeres in the absence of telomerase activity by one or more mechanisms referred to as alternative lengthening of telomeres (ALT). Characteristics of human ALT cells include great heterogeneity of telomere size (ranging from undetectable to abnormally long) within individual cells, and ALT-associated PML bodies (APBs) that contain extrachromosomal telomeric DNA, telomere-specific binding proteins, and proteins involved in DNA recombination and replication. Activation of ALT during immortalization involves recessive mutations in genes that are as yet unidentified. Repressors of ALT activity are present in normal cells and some telomerase-positive cells. Telomere length dynamics in ALT cells suggest a recombinational mechanism. Inter-telomeric copying occurs, consistent with a mechanism in which single-stranded DNA at one telomere terminus invades another telomere and uses it as a copy template resulting in net increase in telomeric sequence. It is possible that t-loops, linear and/or circular extrachromosomal telomeric DNA, and the proteins found in APBs, may be involved in the mechanism. ALT and telomerase activity can co-exist within cultured cells, and within tumors. The existence of ALT adds some complexity to proposed uses of telomere-related parameters in cancer diagnosis and prognosis, and poses challenges for the design of anticancer therapeutics designed to inhibit telomere maintenance.
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Affiliation(s)
- Jeremy D Henson
- Children's Medical Research Institute, 214 Hawkesbury Road, Westmead, Sydney 2145, Australia
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23
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Horikawa I, Parker ES, Solomon GG, Barrett JC. Upregulation of the gene encoding a cytoplasmic dynein intermediate chain in senescent human cells. J Cell Biochem 2001; 82:415-21. [PMID: 11500918 DOI: 10.1002/jcb.1169] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Normal human somatic cells, unlike cancer cells, stop dividing after a limited number of cell divisions through the process termed cellular senescence or replicative senescence, which functions as a tumor-suppressive mechanism and may be related to organismal aging. By means of the cDNA subtractive hybridization, we identified eight genes upregulated during normal chromosome 3-induced cellular senescence in a human renal cell carcinoma cell line. Among them is the DNCI1 gene encoding an intermediate chain 1 of the cytoplasmic dynein, a microtubule motor that plays a role in chromosome movement and organelle transport. The DNCI1 mRNA was also upregulated during in vitro aging of primary human fibroblasts. In contrast, other components of cytoplasmic dynein showed no significant change in mRNA expression during cellular aging. Cell growth arrest by serum starvation, contact inhibition, or gamma-irradiation did not induce the DNCI1 mRNA, suggesting its specific role in cellular senescence. The DNCI1 gene is on the long arm of chromosome 7 where tumor suppressor genes and a senescence-inducing gene for a group of immortal cell lines (complementation group D) are mapped. This is the first report that links a component of molecular motor complex to cellular senescence, providing a new insight into molecular mechanisms of cellular senescence.
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Affiliation(s)
- I Horikawa
- Laboratory of Biosystems and Cancer, Cancer and Aging Section, National Cancer Institute, Bethesda, Maryland 20892, USA.
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24
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Knight JS, Cotter MA, Robertson ES. The latency-associated nuclear antigen of Kaposi's sarcoma-associated herpesvirus transactivates the telomerase reverse transcriptase promoter. J Biol Chem 2001; 276:22971-8. [PMID: 11313352 DOI: 10.1074/jbc.m101890200] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Telomerase is a multi-subunit ribonucleoprotein holoenzyme that stabilizes telomere length through the addition of new repeat sequence to the ends of chromosomes. Telomerase reverse transcriptase is the subunit of this complex responsible for the enzymatic activity of telomerase. Expression of the reverse transcriptase is regulated at the level of transcription through the action of transcription factors that target its promoter. Most Kaposi's sarcoma tumor cells are latently infected with the Kaposi's sarcoma-associated herpesvirus, and the constitutive expression of a viral-encoded latency-associated nuclear antigen has been shown to be important for the maintenance of the viral episome. The proliferative nature of Kaposi's sarcoma suggests that this antigen may also play a critical role in viral-mediated oncogenesis. In this study telomerase reverse transcriptase promoter elements cloned into a luciferase reporter plasmid were analyzed to determine the ability of the latency-associated nuclear antigen to regulate transcription. The latency-associated nuclear antigen transactivated the full-length promoter in 293T, 293, and BJAB cell lines. Furthermore, truncation promoter studies implicated sequence from -130 to +5 in viral-mediated activation. This region contains five Sp1 transcription factor-binding sites. Electrophoretic mobility shift assays indicated that the latency-associated nuclear antigen targets and affects the Sp1-DNA complex in the context of BJAB nuclear extracts.
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Affiliation(s)
- J S Knight
- Medical Scientist Training Program, University of Michigan Medical Center CCGC 3217, Ann Arbor, Michigan 48109-0934, USA
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25
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Suzuki T, Yaginuma M, Oishi T, Michishita E, Ogino H, Fujii M, Ayusawa D. 5-Bromodeoxyuridine suppresses position effect variegation of transgenes in HeLa cells. Exp Cell Res 2001; 266:53-63. [PMID: 11339824 DOI: 10.1006/excr.2001.5194] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An ectopic gene integrated in the host genome is occasionally silenced due to a position effect of its adjacent chromatin structure. We found that 5-bromodeoxyuridine clearly activated such a transgene in HeLa cells. The transgene was also activated to various degrees by inhibitors of histone deacetylase, DNA topoisomerases, or DNA methyltransferase. The peptide antibiotic distamycin A potentiated markedly the effect of 5-bromodeoxyuridine. Transient expression of an artificial AT-hook protein termed MATH20 also potentiated its effect although significantly activated the transgene alone. Since distamycin A and MATH20 are able to displace histone H1 and other DNA-binding proteins bound to specific AT-rich sequences by a dominant, mutually exclusive fashion, these results suggest that 5-bromodeoxyuridine targets such an AT-rich sequence located adjacent to the silenced transgene, resulting in chromatin accessibility.
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Affiliation(s)
- T Suzuki
- Kihara Institute for Biological Research, Yokohama City University, Maioka-cho 641-12, Yokohama 244-0813, Japan
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26
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Ran Q, Wadhwa R, Kawai R, Kaul SC, Sifers RN, Bick RJ, Smith JR, Pereira-Smith OM. Extramitochondrial localization of mortalin/mthsp70/PBP74/GRP75. Biochem Biophys Res Commun 2000; 275:174-9. [PMID: 10944461 DOI: 10.1006/bbrc.2000.3237] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Subcellular fractionation and immunofluorescence microscopy were used to identify the specific sites of intracellular residence of mortalin, also called a mitochondrial homologue of the hsp70 family, in immortal human cell lines previously assigned to four distinct complementation groups (A-D) for indefinite cell division. In addition to the mitochondria it was seen in the endoplasmic reticulum (ER) fractions of all the cell lines analyzed. Interestingly, three of the group A cells lines (EJ, GM639, and HT1080), in addition to the mitochondria and ER, exhibited cytosolically (extra-organelle) localized pool of mortalin. These findings demonstrate that mortalin is not present exclusively in mitochondria. Its residence in different organelles may be the basis of differential distribution observed previously in different human cell lines.
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Affiliation(s)
- Q Ran
- Roy M. and Phyllis Gough Huffington Center on Aging, Department of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030, USA
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27
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Affiliation(s)
- T Tsuji
- Department of Cell Biology, Institute of Molecular and Cellular Biology, Okayama University Medical School, Shikata-cho 2-5-1, 700-8558, Okayama, Japan
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28
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Abstract
Normal somatic cells are able to divide only a limited number of times before they become senescent. The occurrence of intratumoral cell death and the need for clonal evolution mean that many more cell divisions are required for tumorigenesis than is possible unless cells breach the senescence proliferation barrier and become immortalized. Senescence may therefore be a major tumor suppressor mechanism. During the past decade the study of senescence and immortalization has entered the mainstream of cancer research. A major reason for the current interest in this subject is the observation that most cancers have an activated telomere maintenance mechanism, a marker of immortalization. It has also been found that some of the most common genetic changes known to occur in cancer have a key role in the immortalization process.
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Affiliation(s)
- R R Reddel
- Children's Medical Research Institute, 214 Hawkesbury Road, Westmead, Sydney, NSW 2145, Australia.
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29
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Simons JW. A theory on cellular aging and cell immortalization. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1999; 24:1-21. [PMID: 10547856 DOI: 10.1007/978-3-662-06227-2_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- J W Simons
- Department of Radiation Genetics and Chemical Mutagenesis, MGC, Leiden University, The Netherlands
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30
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Wadhwa R, Kaul SC, Mitsui Y. Cellular mortality and immortalization: a complex interplay of multiple gene functions. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1999; 24:191-204. [PMID: 10547864 DOI: 10.1007/978-3-662-06227-2_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Affiliation(s)
- R Wadhwa
- Chugai Research Institute for Molecular Medicine, Ibaraki, Japan
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31
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Abstract
The immortalization of human diploid fibroblasts requires the circumvention of both the senescence (M1) and crisis (M2) mechanisms of growth control. Cells expressing the SV40 T antigen virtually always bypass senescence, but only rarely escape crisis. The low frequency of this latter event indicates that cellular mutations are necessary to escape crisis. Thirteen subpopulations of T antigen-expressing human fibroblasts were cultured into crisis. Colonies that appeared to resume growth were assayed for telomerase activity, telomere maintenance, and the immortal phenotype. Our results show that 33 of 35 colonies were telomerase negative and were not immortal. Two colonies were telomerase positive when assayed in the first approximately 15 population doublings after crisis. The first was strongly positive, maintained telomeres at a stable short length, and was later determined to be immortal. The second initially had a weak telomerase signal, grew extremely slowly, and when examined had greatly elongated telomeres consistent with the ALT (alternative lengthening of telomeres) mechanism of telomere maintenance. These cells eventually grew faster and were later determined to be immortal. Additionally, two subpopulations had initially weak and later strong telomerase activity and the cells never entered a defined crisis period. We observed a perfect correlation between telomere maintenance and escape from crisis, supporting the hypothesis that the lack of stable telomeres causes crisis and that the ability to maintain telomeres abrogates crisis.
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Affiliation(s)
- M C Montalto
- Department of Microbiology, Immunology and Molecular Genetics, Albany, Medical College, New York 12208, USA
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Perrem K, Bryan TM, Englezou A, Hackl T, Moy EL, Reddel RR. Repression of an alternative mechanism for lengthening of telomeres in somatic cell hybrids. Oncogene 1999; 18:3383-90. [PMID: 10362359 DOI: 10.1038/sj.onc.1202752] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Some immortalized cell lines maintain their telomeres in the absence of detectable telomerase activity by an alternative (ALT) mechanism. To study how telomere maintenance is controlled in ALT cells, we have fused an ALT cell line GM847 (SV40 immortalized human skin fibroblasts) with normal fibroblasts or with telomerase positive immortal human cell lines and have examined their proliferative potential and telomere dynamics. The telomeres in ALT cells are characteristically very heterogeneous in length, ranging from very short to very long. The ALT x normal hybrids underwent a rapid reduction in telomeric DNA and entered a senescence-like state. Immortal segregants rapidly reverted to the ALT telomere phenotype. Fusion of ALT cells to telomerase-positive immortal cells in the same immortalization complementation group resulted in hybrids that appeared immortal and also exhibited repression of the ALT telomere phenotype. In these hybrids, which were all telomerase-positive, we observed an initial rapid loss of most long telomeres, followed either by gradual loss of the remaining long telomeres at a rate similar to the rate of telomere shortening in normal telomerase-negative cells, or by maintenance of shortened telomeres. These data indicate the existence of a mechanism of rapid telomere deletion in human cells. They also demonstrate that normal cells and at least some telomerase-positive immortal cells contain repressors of the ALT telomere phenotype.
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Affiliation(s)
- K Perrem
- Cancer Research Group, Children's Medical Research Institute, Sydney, NSW, Australia
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Abstract
Immortal cell populations are able to proliferate indefinitely. Immortalization is associated with activation of processes that compensate for the telomeric shortening that accompanies cell division in normal somatic cells. In many immortal cell lines, telomere maintenance is provided by the action of the ribonucleoprotein enzyme complex, telomerase. Some immortal cell lines have undetectable or very low levels of telomerase activity and there is evidence that these cells maintain their telomeres by an alternative mechanism.
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Affiliation(s)
- L M Colgin
- Children's Medical Research Institute, 214 Hawkesbury Road, Westmead, NSW 2145, Australia
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Michishita E, Nakabayashi K, Ogino H, Suzuki T, Fujii M, Ayusawa D. DNA topoisomerase inhibitors induce reversible senescence in normal human fibroblasts. Biochem Biophys Res Commun 1998; 253:667-71. [PMID: 9918785 DOI: 10.1006/bbrc.1998.9832] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inhibitors of DNA topoisomerases I and II induced arrest in cell division in normal human fibroblasts depending on cell divisions. Arrested cells showed morphology similar to those of normally senesced cells and strongly induced senescence-associated beta-galactosidase. In these cells, p16ink4a was upregulated, whereas p21waf1 or p53 was not altered. Upon removal of the inhibitors, the cells resumed growth but their cumulative population doublings were reduced dose dependently. Accelerated telomere shortening was not observed in the arrested cells. These results suggest that DNA topoisomerase inhibitors are efficient and reversible inducers of premature senescence in normal human cells.
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Affiliation(s)
- E Michishita
- Kihara Institute for Biological Research and Graduate School of Integrated Science, Yokohama City University, Yokohama, Japan
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Abstract
According to the telomere hypothesis of senescence, the telomeric shortening that accompanies the replication of normal somatic cells acts as the mitotic clock that eventually results in their permanent exit from the cell cycle. Although evidence consistent with the telomere hypothesis continues to accumulate, on the basis of recent findings it is suggested that instead of a single clock mechanism there are multiple inducers of senescence.
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Affiliation(s)
- R R Reddel
- Children's Medical Research Institute, Wentworthville, NSW, Australia.
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Ogino H, Nakabayashi K, Suzuki M, Takahashi E, Fujii M, Suzuki T, Ayusawa D. Release of telomeric DNA from chromosomes in immortal human cells lacking telomerase activity. Biochem Biophys Res Commun 1998; 248:223-7. [PMID: 9675117 DOI: 10.1006/bbrc.1998.8875] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Some immortal human cell lines lack telomerase activity. These cell lines were found to contain small dispersed DNA hybridizing to TTAGGG repeats. Such DNA was located in their cytoplasm and nuclei. Normal human fibroblasts or telomerase-positive cell lines did not contain such DNA. Upon cloning and sequencing, it was shown to consist of TTAGGG repeats. When electrophoresed on neutral and alkaline agarose gels, it behaved as double-stranded and linear DNA. These results suggest that telomeric DNA is released from chromosomes in association with maintenance of telomeres in telomerase-negative cell lines.
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Affiliation(s)
- H Ogino
- Kihara Institute for Biological Research and Graduate School of Integrated Science, Yokohama City University, Totsuka-ku, Maioka-cho, Yokohama, 244-0813, Japan
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Ide A, Fujii M, Nakababashi K, Ayusawa D. Suppression of senescence in normal human fibroblasts by introduction of dominant-negative p53 mutants or human papilloma virus type 16 E6 protein. Biosci Biotechnol Biochem 1998; 62:1458-60. [PMID: 9720232 DOI: 10.1271/bbb.62.1458] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Transfection of nearly senesced human fibroblasts with plasmids encoding HPV16 E6 protein or dominant-negative p53 mutants greatly increased their colony-forming ability. Isolated colonies with these plasmids showed extension of lifespan compared to those with a control plasmid. These data demonstrate that p53 plays a major role in senescence in normal human fibroblasts.
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Affiliation(s)
- A Ide
- Division of Biochemistry, Kihara Institute for Biological Research, Yokohama, Japan
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Liang H, Fairman J, Claxton DF, Nowell PC, Green ED, Nagarajan L. Molecular anatomy of chromosome 7q deletions in myeloid neoplasms: evidence for multiple critical loci. Proc Natl Acad Sci U S A 1998; 95:3781-5. [PMID: 9520444 PMCID: PMC19914 DOI: 10.1073/pnas.95.7.3781] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Complete or partial deletions of the long arm of chromosome 7 (7q- and -7) are nonrandom abnormalities seen in primary and therapy-induced myelodysplasia (MDS) and acute myelogenous leukemia (AML). Monosomy 7, occurring as the sole cytogenetic anomaly in a small but significant number of cases, may denote a dominant mechanism involving critical tumor suppressor gene(s). We have determined the extent of allele loss in cytogenetically prescreened MDS and AML patients for microsatellite markers from chromosome 7q22 and 7q31. Whereas >80% of these cases revealed allele loss for the entire region, a rare case of the 7q- chromosome showed allele loss for only the proximal 7q31.1 loci flanked by the markers D7S486 and D7S2456, and a case of monosomy 7 revealed allele loss for loci at both 7q31 and 7q22 with retention of sequences between these sets of loci. Furthermore, a case of AML with no cytogenetic anomaly of chromosome 7 revealed a submicroscopic allelic imbalance for a third distal locus, D7S677. These findings suggest the presence of three distinct critical loci that may contribute alone or in combination to the evolution of MDS and AML. The data also provide molecular evidence for unbalanced translocation with noncontiguous deletions, as an alternate mechanism underlying monosomy 7.
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Affiliation(s)
- H Liang
- Department of Molecular Hematology and Therapy, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
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