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Smith P, Carroll B. Senescence in the ageing skin: a new focus on mTORC1 and the lysosome. FEBS J 2024. [PMID: 39325694 DOI: 10.1111/febs.17281] [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: 04/10/2024] [Revised: 07/23/2024] [Accepted: 09/09/2024] [Indexed: 09/28/2024]
Abstract
Ageing is defined as the progressive loss of tissue function and regenerative capacity and is caused by both intrinsic factors i.e. the natural accumulation of damage, and extrinsic factors i.e. damage from environmental stressors. Cellular senescence, in brief, is an irreversible exit from the cell cycle that occurs primarily in response to excessive cellular damage, such as from ultraviolet (UV) exposure and oxidative stress, and it has been comprehensively demonstrated to contribute to tissue and organismal ageing. In this review, we will focus on the skin, an organ which acts as an essential protective barrier against injury, insults, and infection. We will explore the evidence for the existence and contribution of cellular senescence to skin ageing. We discuss the known molecular mechanisms driving senescence in the skin, with a focus on the dysregulation of the master growth regulator, mechanistic Target of Rapamycin Complex 1 (mTORC1). We explore the interplay of dysregulated mTORC1 with lysosomes and how they contribute to senescence phenotypes.
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2
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Maity P, Singh K, Krug L, Koroma A, Hainzl A, Bloch W, Kochanek S, Wlaschek M, Schorpp-Kistner M, Angel P, Ignatius A, Geiger H, Scharffetter-Kochanek K. Persistent JunB activation in fibroblasts disrupts stem cell niche interactions enforcing skin aging. Cell Rep 2021; 36:109634. [PMID: 34469740 DOI: 10.1016/j.celrep.2021.109634] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 06/15/2021] [Accepted: 08/09/2021] [Indexed: 01/02/2023] Open
Abstract
Fibroblasts residing in the connective tissues constitute the stem cell niche, particularly in organs such as skin. Although the effect of fibroblasts on stem cell niches and organ aging is an emerging concept, the underlying mechanisms are largely unresolved. We report a mechanism of redox-dependent activation of transcription factor JunB, which, through concomitant upregulation of p16INK4A and repression of insulin growth factor-1 (IGF-1), initiates the installment of fibroblast senescence. Fibroblast senescence profoundly disrupts the metabolic and structural niche, and its essential interactions with different stem cells thus enforces depletion of stem cells pools and skin tissue decline. In fact, silencing of JunB in a fibroblast-niche-specific manner-by reinstatement of IGF-1 and p16 levels-restores skin stem cell pools and overall skin tissue integrity. Here, we report a role of JunB in the control of connective tissue niche and identified targets to combat skin aging and associated pathologies.
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Affiliation(s)
- Pallab Maity
- Department of Dermatology and Allergic Diseases, Ulm University, 89081 Ulm, Germany; Aging Research Center (ARC), 89081 Ulm, Germany.
| | - Karmveer Singh
- Department of Dermatology and Allergic Diseases, Ulm University, 89081 Ulm, Germany; Aging Research Center (ARC), 89081 Ulm, Germany
| | - Linda Krug
- Department of Dermatology and Allergic Diseases, Ulm University, 89081 Ulm, Germany
| | - Albert Koroma
- Department of Dermatology and Allergic Diseases, Ulm University, 89081 Ulm, Germany; Aging Research Center (ARC), 89081 Ulm, Germany
| | - Adelheid Hainzl
- Department of Dermatology and Allergic Diseases, Ulm University, 89081 Ulm, Germany
| | - Wilhelm Bloch
- Institute of Cardiology and Sports Medicine, Molecular and cellular Sports Medicine, German Sport University Cologne, 50933 Cologne, Germany
| | - Stefan Kochanek
- Department of Gene Therapy, University of Ulm, 89081 Ulm, Germany
| | - Meinhard Wlaschek
- Department of Dermatology and Allergic Diseases, Ulm University, 89081 Ulm, Germany
| | - Marina Schorpp-Kistner
- Division of Signal Transduction and Growth Control, German Cancer Research Center (DKFZ) and DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Peter Angel
- Division of Signal Transduction and Growth Control, German Cancer Research Center (DKFZ) and DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Anita Ignatius
- Institute of Orthopaedic Research and Biomechanics, Ulm University, 89081 Ulm, Germany
| | - Hartmut Geiger
- Aging Research Center (ARC), 89081 Ulm, Germany; Institute of Molecular Medicine and Stem Cell Aging, Ulm University, 89081 Ulm, Germany; Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center and University of Cincinnati, Cincinnati, OH 45229, USA
| | - Karin Scharffetter-Kochanek
- Department of Dermatology and Allergic Diseases, Ulm University, 89081 Ulm, Germany; Aging Research Center (ARC), 89081 Ulm, Germany.
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Simultaneous Targeting Tumor Cells and Cancer-Associated Fibroblasts with a Paclitaxel-Hyaluronan Bioconjugate: In Vitro Evaluation in Non-Melanoma Skin Cancer. Biomedicines 2021; 9:biomedicines9060597. [PMID: 34073987 PMCID: PMC8225214 DOI: 10.3390/biomedicines9060597] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/13/2021] [Accepted: 05/19/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Cancer-associated fibroblasts (CAFs) facilitate many aspects of cancer development by providing a structural framework rich in bioactive compounds. There are emerging studies proposing a combination of conventional anti-cancer therapies directed against neoplastic cells to molecules targeting tumor microenvironments. METHODS The study evaluated the pharmacological properties of the anti-tumor agent paclitaxel conjugated to hyaluronic acid (HA) regarding non-melanoma skin cancer (NMSC) and the surrounding fibroblasts. This molecule, named Oncofid-P20 (Onco-P20), preferentially targets cells expressing high levels of CD44, the natural ligand of HA. RESULTS Consistent with paclitaxel's mechanism of action involving interference with the breakdown of microtubules during cell division, highly sensitive carcinoma cells rapidly underwent apoptotic cell death. Interestingly, less sensitive cells, such as dermal fibroblasts, resisted the Onco-P20 treatment and experienced a prolonged growth arrest characterized by morphological change and significant modification of the gene expression profile. Onco-P20-treated fibroblasts exhibited reduced growth factor production, downmodulation of the Wnt signaling pathway, and the acquisition of a marked pro-inflammatory profile. Independently of direct exposure to taxol, in the presence of Onco-P20-treated fibroblasts or in their conditioned medium, carcinoma cells had a reduced proliferation rate. Similar to NHF, fibroblasts isolated from skin cancer lesions or from adjacent tissue acquired anti-neoplastic activity under Onco-P20 treatment. CONCLUSION Collectively, our data demonstrate that Onco-P20, exerting both a direct and an NHF-mediated indirect effect on carcinoma cells, is a candidate for an innovative therapy alternative to surgery for the treatment of NMSC.
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Hutcherson RJ, Gabbard RD, Castellanos AJ, Travers JB, Kemp MG. Age and insulin-like growth factor-1 impact PCNA monoubiquitination in UVB-irradiated human skin. J Biol Chem 2021; 296:100570. [PMID: 33753168 PMCID: PMC8065225 DOI: 10.1016/j.jbc.2021.100570] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/15/2021] [Accepted: 03/18/2021] [Indexed: 11/30/2022] Open
Abstract
Nonmelanoma skin cancers occur primarily in individuals over the age of 60 and are characterized by an abundance of ultraviolet (UV) signature mutations in keratinocyte DNA. Though geriatric skin removes UV photoproducts from DNA less efficiently than young adult skin, it is not known whether the utilization of other prosurvival but potentially mutagenic DNA damage tolerance systems such as translesion synthesis (TLS) is altered in older individuals. Using monoubiquitination of the replicative DNA polymerase clamp protein PCNA (proliferating cell nuclear antigen) as a biochemical marker of TLS pathway activation, we find that UVB exposure of the skin of individuals over the age of 65 results in a higher level of PCNA monoubiquitination than in the skin of young adults. Furthermore, based on previous reports showing a role for deficient insulin-like growth factor-1 (IGF-1) signaling in altered UVB DNA damage responses in geriatric human skin, we find that both pharmacological inhibition of the IGF-1 receptor (IGF-1R) and deprivation of IGF-1 potentiate UVB-induced PCNA monoubiquitination in both human skin ex vivo and keratinocytes in vitro. Interestingly, though the TLS DNA polymerase Pol eta can accurately replicate the major photoproducts induced in DNA by UV radiation, we find that it fails to accumulate on chromatin in the absence of IGF-1R signaling and that this phenotype is correlated with increased mutagenesis in keratinocytes in vitro. Thus, altered IGF-1/IGF-1R signaling in geriatric skin may predispose epidermal keratinocytes to carry out a more mutagenic form of DNA synthesis following UVB exposure.
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Affiliation(s)
- Rebekah J Hutcherson
- Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, Ohio, USA
| | - Ryan D Gabbard
- Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, Ohio, USA
| | - Amber J Castellanos
- Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, Ohio, USA
| | - Jeffrey B Travers
- Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, Ohio, USA; Department of Dermatology, Wright State University Boonshoft School of Medicine, Dayton, Ohio, USA; Dayton Veterans Affairs Medical Center, Dayton, Ohio, USA
| | - Michael G Kemp
- Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, Ohio, USA.
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Alkawar AMM, Castellanos AJ, Carpenter MA, Hutcherson RJ, Madkhali MAO, Johnson RM, Bottomley M, Kemp MG. Insulin-like Growth Factor-1 Impacts p53 Target Gene Induction in UVB-irradiated Keratinocytes and Human Skin. Photochem Photobiol 2020; 96:1332-1341. [PMID: 32416609 DOI: 10.1111/php.13279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 05/05/2020] [Indexed: 12/19/2022]
Abstract
The tumor suppressor protein p53 limits mutagenesis in response to ultraviolet-B (UVB) light exposure by activating the transcription of genes that mitigate the damaging effects of UVB radiation on DNA. Because most nonmelanoma skin cancers (NMSCs) occur in older individuals, it is important to understand the process of mutagenesis in the geriatric skin microenvironment. Based on previous studies demonstrating that geriatric skin expresses lower levels of the growth factor insulin-like growth factor-1 (IGF-1) than young adult skin, a role for IGF-1 in the regulation of p53 target genes was investigated in both human keratinocytes in vitro and human skin explants ex vivo. The products of the p53 target genes p21 and DNA polymerase eta (pol η) were found to be increased by UVB exposure in both experimental systems, and this induction was observed to be partially abrogated by depriving keratinocytes of IGF-1 in vitro or by the treatment of keratinocytes in vitro and human skin explants with an IGF-1 receptor antagonist. Because p21 and pol η function to limit mutagenic DNA replication following UVB exposure, these results suggest that NMSC risk in geriatric populations may be due to age-dependent decreases in IGF-1 signaling that disrupt p53 function in the skin.
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Affiliation(s)
- Abdulrahman M M Alkawar
- Departments of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH
| | - Amber J Castellanos
- Departments of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH
| | - Mae Alexandra Carpenter
- Departments of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH
| | - Rebekah J Hutcherson
- Departments of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH
| | - Mariyyah A O Madkhali
- Departments of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH
| | - Ron Michael Johnson
- Department of Surgery, Boonshoft School of Medicine, Wright State University, Dayton, OH
| | | | - Michael G Kemp
- Departments of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH
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Muraguchi T, Nanba D, Nishimura EK, Tashiro T. IGF-1R deficiency in human keratinocytes disrupts epidermal homeostasis and stem cell maintenance. J Dermatol Sci 2019; 94:298-305. [PMID: 31122679 DOI: 10.1016/j.jdermsci.2019.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/20/2019] [Accepted: 05/08/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND Epidermal stem cells (ESCs) are keratinocytes that reside in the basal layer of the epidermis and mediate epidermal homeostasis. Insulin-like growth factor 1 (IGF-1) signaling through its receptor (IGF-1R) has been identified as an important regulator in rodent skin development and differentiation. However, the role of IGF-1/IGF-1R signaling in human keratinocytes is not yet well understood. OBJECTIVE This study aimed to clarify the role of IGF-1/IGF-1R signaling in human epidermal homeostasis. METHODS IGF-1R specific knockout (KO) HaCaT keratinocytes were generated by CRISPR-Caspase-9-mediated non-homologous end joining frame-shift mutations. Further, the behavior of these keratinocytes in epidermal homeostasis was investigated using reconstructed epidermis and human skin equivalents. RESULTS IGF-1R KO HaCaT keratinocytes were successfully established and produced thin epidermis in three-dimensional culture models. Keratin10-positive cells were frequently found in the basal layer of the reconstructed epidermis. CONCLUSIONS IGF-1/IGF-1R signaling was demonstrated to play a key role in maintaining human epidermal homeostasis. This method provides a new framework to investigate gene function in human epidermal homeostasis.
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Affiliation(s)
- Taichi Muraguchi
- Bioscience & Technology Development Center, FUJIFILM Corporation, 577 Kaisei, Kanagawa 258-8577, Japan; Department of Stem Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Daisuke Nanba
- Department of Stem Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Emi K Nishimura
- Department of Stem Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Tomoko Tashiro
- Pharmaceutical & Healthcare Research Laboratories, FUJIFILM Corporation, 577 Kaisei, Kanagawa 258-8577, Japan
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Mainzer C, Remoué N, Molinari J, Rousselle P, Barricchello C, Lago JC, Sommer P, Sigaudo-Roussel D, Debret R. In vitro epidermis model mimicking IGF-1-specific age-related decline. Exp Dermatol 2019; 27:537-543. [PMID: 29603432 DOI: 10.1111/exd.13547] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2018] [Indexed: 12/13/2022]
Abstract
Ageing is a complex multifaceted process affecting skin functionality and structure. Several 3D organotypic skin culture models have reproduced ageing by inducing replicative senescence, glycation or oxidative stress. Yet, very few models have focused on hormonal ageing and especially the insulin-like growth factor 1 (IGF-1) signalling pathway, which has been associated with longevity in animal studies and is necessary for the early stages of skin development. In this study, we built an organotypic epidermis model with targeted IGF-1 receptor knockdown to reproduce some aspects of hormonal ageing on skin. Our model displayed morphological and functional features of aged epidermis, which were mostly attributed to a loss of function of the Stratum basale. IGF-1 receptor knockdown keratinocytes depicted an extended cell cycle, reduced proliferation potential and reduced adhesion capacities and greater sensitivity to oxidative stress than control cells. Altogether, this model represents an essential tool for further investigations into the mechanisms linked to some aspects of hormonal decline or when screening for potent anti-ageing compounds.
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Affiliation(s)
- Carine Mainzer
- Laboratoire de Biologie Tissulaire et Ingénierie Thérapeutique, UMR5305 CNRS/Université Lyon 1, Lyon, France
| | - Noëlle Remoué
- Laboratoire de Biologie Tissulaire et Ingénierie Thérapeutique, UMR5305 CNRS/Université Lyon 1, Lyon, France
| | - Jennifer Molinari
- Natura Inovação e Tecnologia de Produtos, Cajamar, São Paulo, Brasil
| | - Patricia Rousselle
- Laboratoire de Biologie Tissulaire et Ingénierie Thérapeutique, UMR5305 CNRS/Université Lyon 1, Lyon, France
| | | | - Juliana C Lago
- Natura Inovação e Tecnologia de Produtos, Cajamar, São Paulo, Brasil
| | - Pascal Sommer
- Laboratoire de Biologie Tissulaire et Ingénierie Thérapeutique, UMR5305 CNRS/Université Lyon 1, Lyon, France
| | - Dominique Sigaudo-Roussel
- Laboratoire de Biologie Tissulaire et Ingénierie Thérapeutique, UMR5305 CNRS/Université Lyon 1, Lyon, France
| | - Romain Debret
- Laboratoire de Biologie Tissulaire et Ingénierie Thérapeutique, UMR5305 CNRS/Université Lyon 1, Lyon, France
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8
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Impact of Age and Insulin-Like Growth Factor-1 on DNA Damage Responses in UV-Irradiated Human Skin. Molecules 2017; 22:molecules22030356. [PMID: 28245638 PMCID: PMC5432641 DOI: 10.3390/molecules22030356] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 02/22/2017] [Accepted: 02/24/2017] [Indexed: 01/19/2023] Open
Abstract
The growing incidence of non-melanoma skin cancer (NMSC) necessitates a thorough understanding of its primary risk factors, which include exposure to ultraviolet (UV) wavelengths of sunlight and age. Whereas UV radiation (UVR) has long been known to generate photoproducts in genomic DNA that promote genetic mutations that drive skin carcinogenesis, the mechanism by which age contributes to disease pathogenesis is less understood and has not been sufficiently studied. In this review, we highlight studies that have considered age as a variable in examining DNA damage responses in UV-irradiated skin and then discuss emerging evidence that the reduced production of insulin-like growth factor-1 (IGF-1) by senescent fibroblasts in the dermis of geriatric skin creates an environment that negatively impacts how epidermal keratinocytes respond to UVR-induced DNA damage. In particular, recent data suggest that two principle components of the cellular response to DNA damage, including nucleotide excision repair and DNA damage checkpoint signaling, are both partially defective in keratinocytes with inactive IGF-1 receptors. Overcoming these tumor-promoting conditions in aged skin may therefore provide a way to lower aging-associated skin cancer risk, and thus we will consider how dermal wounding and related clinical interventions may work to rejuvenate the skin, re-activate IGF-1 signaling, and prevent the initiation of NMSC.
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Abstract
Development of therapeutic approaches that slow or ablate the adverse physiological and pathological changes associated with aging has been considered as an important goal for gerontological research. As cellular senescence is characterized as the basis for aging in organisms, culturing and subculturing of normal human diploid fibroblasts to mimic the in vivo aging processes have been developed as major methods to investigate molecular events involved in aging. It has been established that normal human diploid fibroblasts can proliferate in culture for only finite periods of time. There are many ways to study aging in vitro. In this chapter, we will discuss some of the basic laboratory procedures for cell senescence culturing methods.
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10
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Póvoa G, Diniz LM. Growth hormone system: skin interactions. An Bras Dermatol 2012; 86:1159-65. [PMID: 22281905 DOI: 10.1590/s0365-05962011000600015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 02/09/2011] [Indexed: 11/21/2022] Open
Abstract
This paper describes the growth hormone system, emphasizing its possible effects on epidermal cells, dermal structures and wound healing. A review of the literature was conducted on studies concerning the growth hormone molecule, its receptor and carrier proteins and the other proteins involved in the mechanisms of its manifestation in dermal tissue.
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Affiliation(s)
- Guilherme Póvoa
- Department of Internal Medicine, Health Sciences Center, Federal University of Espírito Santo, Vitória, ES, Brazil.
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11
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Micutkova L, Diener T, Li C, Rogowska-Wrzesinska A, Mueck C, Huetter E, Weinberger B, Grubeck-Loebenstein B, Roepstorff P, Zeng R, Jansen-Duerr P. Insulin-like growth factor binding protein-6 delays replicative senescence of human fibroblasts. Mech Ageing Dev 2011; 132:468-79. [PMID: 21820463 PMCID: PMC3192261 DOI: 10.1016/j.mad.2011.07.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 07/08/2011] [Accepted: 07/15/2011] [Indexed: 01/10/2023]
Abstract
Cellular senescence can be induced by a variety of mechanisms, and recent data suggest a key role for cytokine networks to maintain the senescent state. Here, we have used a proteomic LC-MS/MS approach to identify new extracellular regulators of senescence in human fibroblasts. We identified 26 extracellular proteins with significantly different abundance in conditioned media from young and senescent fibroblasts. Among these was insulin-like growth factor binding protein-6 (IGFBP-6), which was chosen for further analysis. When IGFBP-6 gene expression was downregulated, cell proliferation was inhibited and apoptotic cell death was increased. Furthermore, downregulation of IGFBP-6 led to premature entry into cellular senescence. Since IGFBP-6 overexpression increased cellular lifespan, the data suggest that IGFBP-6, in contrast to other IGF binding proteins, is a negative regulator of cellular senescence in human fibroblasts.
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Affiliation(s)
- Lucia Micutkova
- Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria
| | - Thomas Diener
- Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria
| | - Chen Li
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Adelina Rogowska-Wrzesinska
- Protein Research Group, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense M, Denmark
| | - Christoph Mueck
- Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria
| | - Eveline Huetter
- Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria
| | - Birgit Weinberger
- Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria
| | - Beatrix Grubeck-Loebenstein
- Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria
| | - Peter Roepstorff
- Protein Research Group, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense M, Denmark
| | - Rong Zeng
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Pidder Jansen-Duerr
- Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria
- Corresponding author. Tel.: +43 512 583919 44; fax: +43 512 583919 8.
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12
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Abstract
Cellular senescence is a specialized form of growth arrest, confined to mitotic cells, induced by various stressful stimuli and characterized by a permanent growth arrest, resistance to apoptosis, an altered pattern of gene expression and the expression of some markers that are characteristic, although not exclusive, to the senescent state. Senescent cells profoundly modify neighboring and remote cells through the production of an altered secretome, eventually leading to inflammation, fibrosis and possibly growth of neoplastic cells. Mammalian aging has been defined as a reduction in the capacity to adequately maintain tissue homeostasis or to repair tissues after injury. Tissue homeostasis and regenerative capacity are nowadays considered to be related to the stem cell pool present in every tissue. For this reason, pathological and patho-physiological conditions characterized by altered tissue homeostasis and impaired regenerative capacity can be viewed as a consequence of the reduction in stem cell number and/or function. Last, cellular senescence is a double-edged sword, since it may inhibit the growth of transformed cells, preventing the occurrence of cancer, while it may facilitate growth of preneoplastic lesions in a paracrine fashion; therefore, interventions targeting this cell response to stress may have a profound impact on many age-related pathologies, ranging from cardiovascular disease to oncology. Aim of this review is to discuss both molecular mechanisms associated with stem cell senescence and interventions that may attenuate or reverse this process.
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13
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Mück C, Herndler-Brandstetter D, Micutkova L, Grubeck-Loebenstein B, Jansen-Dürr P. Two functionally distinct isoforms of TL1A (TNFSF15) generated by differential ectodomain shedding. J Gerontol A Biol Sci Med Sci 2010; 65:1165-80. [PMID: 20675618 PMCID: PMC2954241 DOI: 10.1093/gerona/glq129] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tumor necrosis factor–like cytokine 1A (TL1A) is expressed in endothelial cells and contributes to T-cell activation, via an extracellular fragment TL1AL72-L251, generated by ectodomain shedding. Fragments of TL1A, referred to as vascular endothelial growth inhibitor, were found to induce growth arrest and apoptosis in endothelial cells; however, the underlying mechanisms remained obscure. Here, we show that full-length TL1A is the major detectable gene product in both human umbilical vein endothelial cells and circulating endothelial progenitor cells. TL1A expression was significantly enhanced in senescent circulating endothelial progenitor cells, and knockdown of TL1A partially reverted senescence. TL1A overexpression induced premature senescence in both circulating endothelial progenitor cells and human umbilical vein endothelial cells. We also identified a novel extracellular fragment of TL1A, TL1AV84-L251, resulting from differential ectodomain shedding, which induced growth arrest and apoptosis in human umbilical vein endothelial cells. These findings suggest that TL1A is involved in the regulation of endothelial cell senescence, via a novel fragment produced by differential ectodomain shedding.
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Affiliation(s)
- Christoph Mück
- Department of Molecular and Cell Biology, Institute for Biomedical Aging Research, Austrian Academy of Sciences, Innsbruck, Austria
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14
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Rattan SIS. Synthesis, Modification and Turnover of Proteins during Aging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 694:1-13. [DOI: 10.1007/978-1-4419-7002-2_1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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15
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Adams PD. Healing and hurting: molecular mechanisms, functions, and pathologies of cellular senescence. Mol Cell 2009; 36:2-14. [PMID: 19818705 DOI: 10.1016/j.molcel.2009.09.021] [Citation(s) in RCA: 242] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Indexed: 01/07/2023]
Abstract
Cellular senescence is a proliferation arrest that is typically irreversible and caused by various cellular stresses, including excess rounds of cell division and cancer-causing genetic alterations. Senescence actively contributes to a tissue-level response to tissue wounding and incipient cancer, healing the tissue and suppressing tumor formation. However, in the long term, the same senescence program may hurt the tissue, thereby contributing to tissue aging. Tumor suppression, wound healing, and aging are each associated with inflammation, and here it is proposed that cellular senescence contributes to a "nonimmune cell" component of the tissue inflammatory response.
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Affiliation(s)
- Peter D Adams
- Cancer Research UK Beatson Labs, University of Glasgow, Glasgow G61 1BD, UK.
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16
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The IGF-1/IGF-1R signaling axis in the skin: a new role for the dermis in aging-associated skin cancer. Oncogene 2009; 29:1475-85. [PMID: 19966862 PMCID: PMC2837099 DOI: 10.1038/onc.2009.440] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The appropriate response of human keratinocytes to UVB is dependent on the activation status of the IGF-1 receptor. Keratinocytes grown in conditions where the IGF-1 receptor is inactive, inappropriately replicate in the presence of UVB-induced DNA damage. In human skin epidermal keratinocytes do not express IGF-1, so the IGF-1 receptor on keratinocytes is activated by IGF-1 secreted from dermal fibroblasts. We now demonstrate that the IGF-1 produced by human fibroblasts is essential for the appropriate UVB response of keratinocytes. Furthermore, the expression of IGF-1 is silenced in senescent fibroblasts in vitro. Using quantitative RT-PCR and immunohistochemisty, we can demonstrate that IGF-1 expression is also silenced in geriatric dermis in vivo. The diminished IGF-1 expression in geriatric skin correlates with an inappropriate UVB response in geriatric volunteers. Finally, the appropriate UVB response is restored in geriatric skin in vivo via pretreatment with exogenous IGF-1. These studies provide further evidence for a role of the IGF-1R in suppressing UVB-induced carcinogenesis, suggest that fibroblasts play a critical role in maintaining appropriate activation of the keratinocyte IGF-1R, and imply that reduced expression of IGF-1 in geriatric skin could be an important component in the development of aging-related non-melanoma skin cancer.
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Abstract
Oncogene-induced cellular senescence constitutes a strong anti-proliferative response, which can be set in motion following either oncogene activation or loss of tumour suppressor signalling. It serves to limit the expansion of early neoplastic cells and as such is a potent cancer-protective response to oncogenic events. Recently emerging evidence points to a crucial role in oncogene-induced cellular senescence for the 'senescence-messaging secretome' or SMS, setting the stage for cross-talk between senescent cells and their environment. How are such signals integrated into a coordinated response and what are the implications of this unexpected finding?
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Affiliation(s)
- Thomas Kuilman
- Division of Molecular Genetics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
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Lewis DA, Travers JB, Spandau DF. A new paradigm for the role of aging in the development of skin cancer. J Invest Dermatol 2008; 129:787-91. [PMID: 18818672 DOI: 10.1038/jid.2008.293] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lewis DA, Yi Q, Travers JB, Spandau DF. UVB-induced senescence in human keratinocytes requires a functional insulin-like growth factor-1 receptor and p53. Mol Biol Cell 2008; 19:1346-53. [PMID: 18216278 DOI: 10.1091/mbc.e07-10-1041] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
To cope with the frequent exposure to carcinogenic UV B (UVB) wavelengths found in sunlight, keratinocytes have acquired extensive protective measures to handle UVB-induced DNA damage. Recent in vitro and epidemiological data suggest one these protective mechanisms is dependent on the functional status of the insulin-like growth factor-1 receptor (IGF-1R) signaling network in keratinocytes. During the normal UVB response, ligand-activated IGF-1Rs protect keratinocytes from UVB-induced apoptosis; however, as a consequence, these keratinocytes fail to proliferate. This adaptive response of keratinocytes to UVB exposure maintains the protective barrier function of the epidermis while ensuring that UVB-damaged keratinocytes do not replicate DNA mutations. In contrast, when keratinocytes are exposed to UVB in the absence of IGF-1R activation, the keratinocytes are more sensitive to UVB-induced apoptosis, but the surviving keratinocytes retain the capacity to proliferate. This aberrant UVB response represents flawed protection from UVB damage potentially resulting in the malignant transformation of keratinocytes. Using normal human keratinocytes grown in vitro, we have demonstrated that activation of the IGF-1R promotes the premature senescence of UVB-irradiated keratinocytes through increased generation of reactive oxygen species (ROS) and by maintaining the expression of the cyclin-dependent kinase inhibitor p21(CDKN1A). Furthermore, IGF-1R-dependent UVB-induced premature senescence required the phosphorylation of p53 serine 46. These data suggest one mechanism of keratinocyte resistance to UVB-induced carcinogenesis involves the induction of IGF-1R-dependent premature senescence.
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Affiliation(s)
- Davina A Lewis
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202-5121, USA
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Abstract
Culturing and subcultivation of normal human diploid fibroblasts have advanced our understanding of the molecular events involved in aging. This progress is leading to the development of therapies that slow or ablate the adverse physiological and pathological changes associated with aging. It has been established that normal human diploid fibroblasts can proliferate in culture for only finite periods of time. Hayflick and Moorhead and others have described numerous types of cells, ranging from fetal to adult, that were incapable of indefinite proliferation. There are many ways to study aging in vitro, and this chapter summarizes some laboratory procedures.
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Affiliation(s)
- Sharla M O Phipps
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA
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Chuang TY, Lewis DA, Spandau DF. Decreased incidence of nonmelanoma skin cancer in patients with type 2 diabetes mellitus using insulin: a pilot study. Br J Dermatol 2005; 153:552-7. [PMID: 16120142 DOI: 10.1111/j.1365-2133.2005.06738.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND In order to prevent the propagation of genetic mutations, human keratinocytes irradiated with ultraviolet (UV) B light in vitro undergo premature stress-induced senescence or apoptosis. This response to UVB irradiation is dependent on the functional activation of the insulin-like growth factor-1 receptor (IGF-1R). Based on this in vitro functional data, we hypothesized that the increased serum levels of insulin in patients with type 2 diabetes may activate the IGF-1R in skin and lead to a decreased frequency of skin cancer in these patients. OBJECTIVES To determine whether the use of insulin by patients with type 2 diabetes correlated with a change in the incidence in nonmelanoma skin cancer (NMSC). METHODS A historical cohort study identifying the incidence of NMSC following the use of two different pharmacological therapies. The patient population was restricted to caucasians who were at least 50 years old when they began the indicated pharmacological therapy. The first group consisted of 1440 patients who used insulin therapy to treat type 2 diabetes and the second group comprised 4135 patients who used cimetidine to treat their gastrointestinal ailments. An additional group of 6131 patients with diabetes who used noninsulin antidiabetics was added to examine the effect of noninsulin therapies. All patients had regular follow-up visits at the Regenstrief Clinics during the study period between 1980 and 1999. The Regenstrief Clinics is an outpatient facility which serves the general population in Metro-Indianapolis, Indiana, U.S.A. RESULTS The incidence of NMSC in patients using insulin was significantly lower than in patients using cimetidine (1.25% vs. 2.35%, P < 0.02). The decrease in NMSC in patients with type 2 diabetes correlated specifically with the use of insulin (NMSC incidence insulin-only patients with diabetes: 1.40% vs. those with diabetes using noninsulin therapies: 2.35%, P = 0.11). CONCLUSIONS Patients using exogenous insulin had a lower risk of developing NMSC and the protective effect of insulin use becomes more distinct with increasing age.
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Affiliation(s)
- T-Y Chuang
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Kobayashi S, Kamino Y, Hiratsuka K, Kiyama-Kishikawa M, Abiko Y. Age-related changes in IGF-1 expression in submandibular glands of senescence-accelerated mice. J Oral Sci 2004; 46:119-25. [PMID: 15287546 DOI: 10.2334/josnusd.46.119] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Saliva is known to play important roles in such functions as swallowing, mastication, speech, and taste. Furthermore, salivary glands synthesize and secrete a number of growth factors involved in cell/tissue homeostasis. It has been demonstrated that IGF-1, which is structurally analogous to insulin, has been shown to be expressed in mouse submandibular glands, and that IGF-1 stimulates DNA synthesis, amino acid uptake, protein synthesis, and glucose transport in various cells. Diminished function of the salivary glands is thought to lead to increased dental caries and periodontal diseases, which are commonly associated with aging. However, very little is known regarding the effects of age on IGF-1 expression in submandibular glands. The senescence-accelerated mouse (SAM), an experimental murine model of accelerated aging, has been extensively used to examine the mechanisms responsible for aging. In the present study, IGF-1 production and mRNA levels in the submandibular glands of SAM-P1 mice were examined. IGF-1 levels were determined by radioimmunoassay and IGF-1 mRNA levels by semi-quantitative RT-PCR. We found that IGF-1 protein levels in homogenates and IGF-1 mRNA levels decreased with age in SAMP1 mice. These findings suggest that IGF-1 synthesis in submandibular glands decreases with aging, and this may result in lower levels of cellular proliferation, regeneration and wound healing in aged oral tissues.
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Affiliation(s)
- Seiko Kobayashi
- Department of Biochemistry, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba, Japan
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Edmondson SR, Thumiger SP, Werther GA, Wraight CJ. Epidermal homeostasis: the role of the growth hormone and insulin-like growth factor systems. Endocr Rev 2003; 24:737-64. [PMID: 14671001 DOI: 10.1210/er.2002-0021] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
GH and IGF-I and -II were first identified by their endocrine activity. Specifically, IGF-I was found to mediate the linear growth-promoting actions of GH. It is now evident that these two growth factor systems also exert widespread activity throughout the body and that their actions are not always interconnected. The literature highlights the importance of the GH and IGF systems in normal skin homeostasis, including dermal/epidermal cross-talk. GH activity, sometimes mediated via IGF-I, is primarily evident in the dermis, particularly affecting collagen synthesis. In contrast, IGF action is an important feature of the dermal and epidermal compartments, predominantly enhancing cell proliferation, survival, and migration. The locally expressed IGF binding proteins play significant and complex roles, primarily via modulation of IGF actions. Disturbances in GH and IGF signaling pathways are implicated in the pathophysiology of several skin perturbations, particularly those exhibiting epidermal hyperplasia (e.g., psoriasis, carcinomas). Additionally, many studies emphasize the potential use of both growth factors in the treatment of skin wounds; for example, burn patients. This overview concerns the role and mechanisms of action of the GH and IGF systems in skin and maintenance of epidermal integrity in both health and disease.
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Affiliation(s)
- Stephanie R Edmondson
- Centre for Hormone Research, Murdoch Children's Research Institute, Royal Children's Hospital, University of Melbourne, Parkville, Victoria, Australia 3052.
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Kanzaki Y, Onoue F, Ishikawa F, Ide T. Telomerase rescues the expression levels of keratinocyte growth factor and insulin-like growth factor-II in senescent human fibroblasts. Exp Cell Res 2002; 279:321-9. [PMID: 12243757 DOI: 10.1006/excr.2002.5607] [Citation(s) in RCA: 19] [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
Changes in expression levels of various cytokines, growth factors, and related genes were examined by reverse transcriptase polymerase chain reaction in a normal human fibroblast cell strain, TIG-3, along with in vitro aging. The expression levels of KGF and IGF-II were decreased with proliferative aging but not by growth arrest of young cells. In telomere-elongated cells prepared by transfection with human telomerase reverse transcriptase cDNA, high expression levels of these two genes were maintained, suggesting a causal relation between telomere shortening and reduced expression of KGF and IGF-II. The expression level of HGF was high in both growing and growth-arrested young cells but low in both senescent and telomere-elongated cells. The expression levels of follistatin and HB-EGF were high in both young growing and telomere-elongated cells but low in both senescent and growth-arrested young cells, indicating a growth-dependent expression. Expression levels of FGF-1, FGF-2, VEGF, BMP-3, and amphiregulin did not change with proliferative aging, growth arrest of young cells, or telomere elongation and life-span extension.
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Affiliation(s)
- Yukari Kanzaki
- Department of Cellular and Molecular Biology, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Hiroshima City, Hiroshima 734-8551, Japan
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Watanabe H, Yu D, Sasaki T, Shibuya H, Hosoi Y, Asada M, Komatsu K, Miura M. Insulin-like growth factor I receptor is expressed at normal levels in Nijmegen breakage syndrome cells. Biochem Biophys Res Commun 2002; 296:62-6. [PMID: 12147227 DOI: 10.1016/s0006-291x(02)00817-3] [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: 10/27/2022]
Abstract
Nijmegen breakage syndrome (NBS) is an autosomal recessive disorder sharing a pleiotropic phenotype with ataxia-telangiectasia (A-T), including increased radiosensitivity and cancer disposition. Insulin-like growth factor I receptor (IGF-IR) expression is reportedly decreased in A-T cells, which is thought to contribute to its increased radiosensitivity. In this study, we investigated whether the same mechanism underlies the radiosensitivity of NBS cells. GM7166VA7 cells lacking NBS1 protein displayed a phenotype of increased radiosensitivity, while the introduction of NBS1 cDNA conferred radioresistance comparable to normal cells. IGF-IR expression levels were essentially the same among normal, NBS, and NBS1-complemented NBS cells. There was no significant difference between NBS and NBS1-complemented cells in activation of major downstream pathways of IGF-IR upon IGF-I stimulation, including phosphatidylinositol-3(') kinase (PI3-K) and mitogen-activated protein kinase (MAPK). Collectively, IGF-IR-related events are unlikely to be disrupted in NBS cells, and therefore, defects in IGF-IR signaling do not explain the increased radiosensitivity of NBS cells.
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Affiliation(s)
- Hiroshi Watanabe
- Oral and Maxillofacial Radiology, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, 113-8549, Tokyo, Japan
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Abstract
Age-related changes in NPY-driven angiogenesis were investigated using Matrigel and aortic sprouting assays in young (2 months.) and aged (18 months.) mice. In both assays, NPY-induced vessel growth decreased significantly with age. In parallel, aged mice showed reduced expression (RT-PCR) of Y2 receptors and the NPY converting enzyme, dipeptidyl peptidase IV (DPPIV), in spleens. Aging of human microvascular endothelial cells in vitro led to a loss of their mitogenic responses to NPY accompanied by a lack of NPY receptor mRNAs. Thus, NPY-dependent angiogenesis is impaired with age, which is associated with a decreased expression of endothelial NPY receptors (Y2) and DPPIV.
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Affiliation(s)
- Joanna Kitlinska
- Department of Physiology and Biophysics, Georgetown University Medical Center, 3900 Reservoir Road NW, Washington, DC 20007, USA.
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Abstract
Ageing concerns the extracellular environment and cells that are either post-mitotic or capable of division during life. Primary human cells have a finite division capacity in culture before they enter a state of viable cell cycle arrest termed senescence. Cell division occurs during life in many tissues, either as part of normal tissue function or in response to tissue damage. The accumulation of cells at the end of their replicative lifespan in the elderly might contribute to aged tissue either because of a reduced ability to undergo proliferation or because of the known altered gene-expression patterns of senescent cells. This has been illustrated experimentally using a transgenic telomerase-negative mouse, which shows some premature ageing phenotypes. The mechanism whereby cells count divisions uses the gradual erosion of the ends of chromosomes (telomeres) with cell division caused by the repression of the telomere-maintenance enzyme telomerase in most human cells. Telomere erosion ultimately triggers replicative senescence in many cell types; this can be prevented experimentally by forcibly expressing telomerase. This extends the lifespan of normal human cells and those from progeroid syndromes such as Werner's. Telomere-driven senescence did not evolve to cause ageing, but is instead a by-product of a system devised to provide a tumour-suppression function, a concept that fits well with evolutionary arguments regarding trade-offs between somatic maintenance and reproduction. Work in the future will focus on the development of new animal models to critically address the quantitative significance of this ageing mechanism.
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Affiliation(s)
- D Kipling
- Department of Pathology, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, UK.
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Kveiborg M, Flyvbjerg A, Rattan SI, Kassem M. Changes in the insulin-like growth factor-system may contribute to in vitro age-related impaired osteoblast functions. Exp Gerontol 2000; 35:1061-74. [PMID: 11121690 DOI: 10.1016/s0531-5565(00)00125-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Age-related bone loss is thought to be due to impaired osteoblast functions. Insulin-like growth factors (IGFs) have been shown to be important stimulators of bone formation and osteoblast activities in vitro and in vivo. We tested the hypothesis that in vitro osteoblast senescence is associated with changes in components of the IGF-system including IGF-I, IGF-II, IGF-binding proteins (IGFBPs) and IGFBP-specific proteases. We employed a human diploid osteoblast cell line obtained from trabecular bone explants and that exhibit typical characteristics of in vitro senescence during serial subculturing. Using a non-competitive reverse-transcriptase polymerase-chain reaction (RT-PCR) assay, we found that the constitutive level of IGF-I mRNA decreased progressively to 49.9 +/- 4.9% in old osteoblasts as compared to the levels found in the young cells. No age-related change was found in IGF-II steady-state mRNA levels. Changes in IGFBPs gene expression and protein production were assessed using Northern blot analysis and Western ligand blotting (WLB), respectively. IGFBP-3 mRNA levels decreased to 30% and protein production to 16% in aged osteoblasts as compared to levels found in young cells. We also found age-related decreases in mRNA levels of both IGFBP-4 and IGFBP-5 to 70% and 60% in aged osteoblasts, respectively, compared to young cells. While IGFBP-5 protein was not detected by WLB, IGFBP-4 protein production showed a biphasic change with 50% decrease in middle-aged cells and a subsequent increase in aged osteoblasts to levels similar to those in young osteoblasts. We found an age-related increase in the immunoreactive levels of IGFBP-4 protease, however, no detectable IGFBP-4 or IGFBP-3 protease activities in conditioned media from osteoblast cultures were observed. Our findings demonstrate that osteoblast aging is associated with impaired production of the stimulatory components of the IGF-system, that may be a mechanism contributing to age-related decline in osteoblast functions.
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Affiliation(s)
- M Kveiborg
- University Department of Endocrinology and Metabolism, Aarhus Amtssygehus, University of Aarhus, DK-8000 Aarhus C, Denmark
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Toussaint O, Medrano EE, von Zglinicki T. Cellular and molecular mechanisms of stress-induced premature senescence (SIPS) of human diploid fibroblasts and melanocytes. Exp Gerontol 2000; 35:927-45. [PMID: 11121681 DOI: 10.1016/s0531-5565(00)00180-7] [Citation(s) in RCA: 463] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Replicative senescence of human diploid fibroblasts (HDFs) or melanocytes is caused by the exhaustion of their proliferative potential. Stress-induced premature senescence (SIPS) occurs after many different sublethal stresses including H(2)O(2), hyperoxia, or tert-butylhydroperoxide. Cells in replicative senescence share common features with cells in SIPS: morphology, senescence-associated beta-galactosidase activity, cell cycle regulation, gene expression and telomere shortening. Telomere shortening is attributed to the accumulation of DNA single-strand breaks induced by oxidative damage. SIPS could be a mechanism of accumulation of senescent-like cells in vivo. Melanocytes exposed to sublethal doses of UVB undergo SIPS. Melanocytes from dark- and light- skinned populations display differences in their cell cycle regulation. Delayed SIPS occurs in melanocytes from light-skinned populations since a reduced association of p16(Ink-4a) with CDK4 and reduced phosphorylation of the retinoblastoma protein are observed. The role of reactive oxygen species in melanocyte SIPS is unclear. Both replicative senescence and SIPS are dependent on two major pathways. One is triggered by DNA damage, telomere damage and/or shortening and involves the activation of the p53 and p21(waf-1) proteins. The second pathway results in the accumulation of p16(Ink-4a) with the MAP kinase signalling pathway as possible intermediate. These data corroborate the thermodynamical theory of ageing, according to which the exposure of cells to sublethal stresses of various natures can trigger SIPS, with possible modulations of this process by bioenergetics.
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Affiliation(s)
- O Toussaint
- Laboratory of Cellular Biochemistry & Biology, Department of Biology, University of Namur (FUNDP), 61, Rue de Bruxelles, B-5000 Namur, Belgium.
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Pfeilschifter J, Diel I, Klöppinger T, Bismar H, Schuster EM, Balbach S, Ziegler R, Baylink D, Mohan S. Concentrations of insulin-like growth factor (IGF)-I, -II, and IGF binding protein-4, and -5 in human bone cell conditioned medium do not change with age. Mech Ageing Dev 2000; 117:109-14. [PMID: 10958927 DOI: 10.1016/s0047-6374(00)00132-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We examined the effects of age on the secretion of insulin-like growth factor (IGF)-I, -II, and IGF binding protein-4, and -5 in long-term bone cell cultures from 71 female donors, aged 28-79 years. Our results suggest that under basal conditions, the intrinsic capacity of human bone cells to produce these IGF components is largely preserved with age.
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Affiliation(s)
- J Pfeilschifter
- Kliniken Bergmannsheil, Department of Internal Medicine, University of Bochum, Bochum, Germany.
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Affiliation(s)
- H L Ozer
- Department of Microbiology and Molecular Genetics UMD-New Jersey Medical School 07103-2714, USA
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Sieuwerts AM, Klijn JG, Foekens JA. Insulin-like growth factor 1 (IGF-1) and urokinase-type plasminogen activator (uPA) are inversely related in human breast fibroblasts. Mol Cell Endocrinol 1999; 154:179-85. [PMID: 10509812 DOI: 10.1016/s0303-7207(99)00098-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Human breast fibroblasts have been shown to express urokinase-type plasminogen activator (uPA). This suggests that fibroblasts are actively involved in the process of uPA-directed breast tumor proteolysis. To investigate a possible role for the insulin-like growth factors (IGFs) in regulating uPA expression in human breast fibroblasts, we correlated the expression of uPA with the expression of IGF-1 and IGF-2 in a paired panel of normal and tumor tissue-derived human breast fibroblasts in vitro. Analysis of reverse transcribed polymerase chain reaction (RT-PCR) amplified mRNA revealed that the tumor-derived fibroblast strain expressed significantly more basal uPA mRNA and significantly less IGF-1 mRNA when compared to their normal counterpart. The expression of basal IGF-2 mRNA did not differ between these cultures. For both normal and tumor tissue-derived fibroblasts, cytokine- and growth factor-induced steady-state levels of uPA and IGF-1 mRNA were inversely related. No such correlation was found for uPA and IGF-2 mRNA. While exogenously added IGF-1 decreased the amount of uPA mRNA transcripts similarly in both normal and tumoral fibroblasts, exogenously added uPA decreased the amount of IGF-1 mRNA transcripts only in tumor tissue-derived fibroblasts. These data suggest that in human breast fibroblasts IGF-1 controls the expression of uPA and that, possibly due to an altered sensitivity to uPA, tumor-associated fibroblasts have escaped this local control mechanism.
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Affiliation(s)
- A M Sieuwerts
- Department of Medical Oncology, Rotterdam Cancer Institute (Daniel den Hoed Kliniek)/Academic Hospital Rotterdam, The Netherlands.
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Macieira-Coelho A. Growth inhibition of human fibroblasts in vitro. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1999; 20:249-70. [PMID: 9928533 DOI: 10.1007/978-3-642-72149-6_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Kuhn C, Hurwitz SA, Kumar MG, Cotton J, Spandau DF. Activation of the insulin-like growth factor-1 receptor promotes the survival of human keratinocytes following ultraviolet B irradiation. Int J Cancer 1999; 80:431-8. [PMID: 9935186 DOI: 10.1002/(sici)1097-0215(19990129)80:3<431::aid-ijc16>3.0.co;2-5] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The ultraviolet B (UVB) component of sunlight causes non-melanoma skin cancers due to the damage it inflicts on genomic DNA. The response of epidermal keratinocytes to sunlight depends on the dose of UVB received and the severity of the damage to the DNA. Mild DNA damage typically induces DNA-repair pathways and cell survival, while severe DNA damage provokes apoptosis. Primary human keratinocytes grown in serum-free media respond in a similar manner to UVB irradiation. However, we observed that keratinocytes are exquisitely more susceptible to UVB-induced apoptosis if the growth medium is depleted of exogenous growth factors. Therefore, an exogenous growth factor could provide protection from UVB-induced apoptosis. We found that the only growth factor that provided protection from UVB-induced apoptosis was insulin and that the protective effect elicited by insulin was not due to binding the insulin receptor but, rather, to activation of the insulin-like growth factor-1 (IGF-1) receptor. Additionally, activation of the IGF-1 receptor in combination with UVB irradiation induced keratinocytes to become post-mitotic. This survival function of the IGF-1 receptor in response to UVB irradiation was influenced by activation of phosphatidylinositol-3 kinase and MAP kinase. Prior to UVB irradiation, insulin or IGF-1 had little to no effect on cell growth or viability. Therefore, activation of the IGF-1 receptor in conjunction with UVB irradiation promotes keratinocyte survival at the expense of cell proliferation.
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Affiliation(s)
- C Kuhn
- Department of Dermatology, Indiana University School of Medicine, Indianapolis 46202-5121, USA
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Abstract
Cell senescence is the limited ability of primary human cells to divide when cultured in vitro. This eventual cessation of division is accompanied by a specific set of changes in cell physiology, morphology, and gene expression. Such changes in phenotype have the potential to contribute to human ageing and age-related diseases. Until now, senescence has largely been studied as an in vitro phenomenon, but recent data have for the first time directly demonstrated the presence of senescent cells in aged human tissues. Although a direct causal link between the ageing of whole organisms and the senescence of cells in culture remains elusive, a large body of data is consistent with cell senescence contributing to a variety of pathological changes seen in the aged. This review considers the in vitro phenotype of cellular senescence and speculates on the various possible routes whereby the presence of senescent cells in old bodies may affect different tissue systems.
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Affiliation(s)
- R G Faragher
- Department of Pharmacy, University of Brighton, UK
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Watanabe S, Wang XE, Hirose M, Kivilioto T, Osada T, Miwa H, Oide H, Kitamura T, Yoneta T, Seto K, Sato N. Insulin-like growth factor I plays a role in gastric wound healing: evidence using a zinc derivative, polaprezinc, and an in vitro rabbit wound repair model. Aliment Pharmacol Ther 1998; 12:1131-8. [PMID: 9845403 DOI: 10.1046/j.1365-2036.1998.00408.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
BACKGROUND Although the detailed mechanism is unclear, zinc and its derivative, polaprezinc, have been reported to accelerate gastric ulcer healing in vivo. AIM To investigate the detailed cellular mechanism of polaprezinc on gastric epithelial cells and fibroblasts with special attention to insulin-like growth factor I (IGF-I). METHODS Isolated rabbit gastric epithelial cells formed a complete monolayer, from which a circular artificial wound with constant size was made. The restoration process was monitored by measuring wound size up to 48 h. Either polaprezinc, IGF-I, fibroblast conditioned medium or neutralized medium conditioned by anti-IGF-I antibody was added at the time of wounding. The expression of mRNA of IGF-I, hepatocyte growth factor (HGF) and transforming growth factor alpha (TGF-alpha) in fibroblasts with or without polaprezinc treatment was tested using reverse transcription polymerase chain reaction (RT-PCR). Gastric epithelial cell proliferation was also examined by bromodeoxyuridine (BrdU) staining. RESULTS IGF-I and fibroblast conditioned medium treatment accelerated gastric epithelial restoration which included cell migration and proliferation. However, polaprezinc and neutralized conditioned medium treatment did not accelerate epithelial repair. RT-PCR for growth factor mRNA revealed the IGF-I mRNA expression in fibroblasts was increased after treatment with polaprezinc. CONCLUSION Polaprezinc induced IGF-I production from mesenchymal cells, resulting in stimulation of epithelial cell restoration through a paracrine pathway. IGF-I may play an important role in gastric wound repair.
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Affiliation(s)
- S Watanabe
- Department of Gastroenterology, Juntendo University School of Medicine, Tokyo, Japan
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Seck T, Scheppach B, Scharla S, Diel I, Blum WF, Bismar H, Schmid G, Krempien B, Ziegler R, Pfeilschifter J. Concentration of insulin-like growth factor (IGF)-I and -II in iliac crest bone matrix from pre- and postmenopausal women: relationship to age, menopause, bone turnover, bone volume, and circulating IGFs. J Clin Endocrinol Metab 1998; 83:2331-7. [PMID: 9661604 DOI: 10.1210/jcem.83.7.4967] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Insulin-like growth factor-I (IGF-I) and -II are important local regulators of bone metabolism, but their role as determinants of human bone mass is still unclear. In the present study, we analyzed the concentration of IGF-I and -II in the bone matrix of 533 human biopsies from the iliac crest that were obtained during surgery for early breast cancer. There was an inverse association of bone matrix IGF-I concentration with age that was unaffected by menopause. Bone matrix IGF-I was positively associated with histomorphometric and biochemical parameters of bone formation and bone resorption and with cancellous bone volume. Based on the estimates of the linear regression analysis, women with a bone matrix IGF-I concentration 2 SD above the mean had a 20% higher bone volume than women with a bone matrix IGF-I concentration 2 SD below the mean. In contrast, serum IGF-I was neither correlated with bone turnover nor with bone volume and was only weakly associated with bone matrix IGF-I when adjusted for the serum concentration of IGF binding protein-3. Bone matrix IGF-II was positively associated with the osteoblast surface, but in contrast to IGF-I, tended to be positively associated with age and was unrelated to cancellous bone volume. In summary, our study suggests the following. 1) The concentration of IGF-I in cancellous bone undergoes age-related decreases that are similar to those of circulating IGF-I. 2) Menopause has no effect on this age-related decline. 3) Physiological differences in bone matrix IGF-I are associated with differences in iliac crest cancellous bone volume. 4) Bone matrix IGF-I is a better predictor of cancellous bone volume than circulating IGF-I. 5) The role of IGF-II in human bone tissue is clearly distinct from that of IGF-I.
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Affiliation(s)
- T Seck
- Department of Internal Medicine, University of Heidelberg, Germany
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Arthur WT, Vernon RB, Sage EH, Reed MJ. Growth factors reverse the impaired sprouting of microvessels from aged mice. Microvasc Res 1998; 55:260-70. [PMID: 9657926 DOI: 10.1006/mvre.1998.2078] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aging is accompanied by impaired angiogenesis and deficient expression of several angiogenic growth factors. To test the hypothesis that replacement of these factors would improve angiogenesis in aged animals, we cultured microvessels derived from the epididymal fat pad of aged and young mice ("aged" and "young" microvessels) in three-dimensional collagen gels for 2 weeks and measured their sprouting (formation of branch points) in response to fetal bovine serum (FBS), endothelial cell growth supplement (ECGS), and the specific growth factors transforming growth factor-beta1 (TGF-beta1), vascular endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF-1), and basic fibroblast growth factor (bFGF). In the presence of culture medium with 1% FBS (Minimal medium), sprouting of aged microvessels was significantly less than sprouting of young microvessels. The addition of high levels of FBS and ECGS to Minimal medium enhanced the sprouting of microvessels from aged mice to a greater degree than that of young mice, such that the difference between the two age groups was no longer significant. Formation of branch points by aged microvessels was also significantly increased by Minimal medium supplemented with TGF-beta1, bFGF, IGF-1, or VEGF (listed in order of highest to lowest stimulation). Sprouts generated in the presence of VEGF possessed a particularly high percentage of endothelial cells. Mitomycin C did not diminish the degree of sprouting induced by TGF-beta1, VEGF, or IGF-1, a result indicating that early stages of angiogenesis, including formation of branch points, do not require cell division. From our findings in vitro, we propose that age-related deficiencies in angiogenesis in vivo are likely to be due, in part, to a decrease in angiogenic growth factors in the extracellular milieu.
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Affiliation(s)
- W T Arthur
- Department of Medicine, University of Washington, Seattle, Washington 98195, USA
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Affiliation(s)
- L M Obeid
- Duke University Medical Center, Department of Medicine, Durham, NC 27710, USA
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Garfinkel S, Wessendorf JH, Hu X, Maciag T. The human diploid fibroblast senescence pathway is independent of interleukin-1 alpha mRNA levels and tyrosine phosphorylation of FGFR-1 substrates. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1314:109-19. [PMID: 8972724 DOI: 10.1016/s0167-4889(96)00105-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In vitro cellular senescence of human umbilical vein endothelial cells (HUVEC) may involve the intracellular activity of the signal peptide-less cytokine interleukin (IL)-1 alpha. To determine whether senescence of other human diploid cells involves the function of IL-1 alpha, we examined the steady-state expression of IL-1 alpha mRNA in IMR-90 fibroblasts. The IL-1 alpha transcript was not elevated in senescent IMR-90 cells. With the exception of the plasminogen activator inhibitor (PAI)-1 transcript, other IL-1 alpha-response gene mRNAs were not induced in senescent IMR-90, although the mRNA for each gene was induced by exogenous IL-1 alpha. The mRNA expression of cell cycle-specific genes demonstrated that Fos and ornithine decarboxylase (ODC) were induced in young and senescent cells in response to both serum and fibroblast growth factor (FGF)-1. Histone (H)3 mRNA was induced by serum in young cells, but not in senescent cells, and FGF-1 failed to induce H3 mRNA in either young or senescent cells. Further, while young IMR-90 populations were able to respond to serum as an initiator of DNA synthesis and cell growth, they did not exhibit a response to exogenous FGF-1. FGF receptor (R)-1 substrates were not tyrosine phosphorylated in either young or senescent IMR-90 cells. These data demonstrate that IL-1 alpha and FGF-1 may have different functions in HUVEC and IMR-90 fibroblast populations including distinct pathways for the regulation of cellular growth and senescence.
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Affiliation(s)
- S Garfinkel
- Department of Molecular Biology, Holland Laboratory, American Red Cross, Rockville, MD 20855, USA
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Ozer HL, Banga SS, Dasgupta T, Houghton J, Hubbard K, Jha KK, Kim SH, Lenahan M, Pang Z, Pardinas JR, Patsalis PC. SV40-mediated immortalization of human fibroblasts. Exp Gerontol 1996; 31:303-10. [PMID: 8706800 DOI: 10.1016/0531-5565(95)00024-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have identified a multistep mechanism by which the DNA virus SV40 overcomes cellular senescence. Expression of SV40 T antigen is required for both transient extension of life span and unlimited life span or immortalization. These effects are mediated through inactivation of function of growth suppressors pRB and p53 via complex formation with T antigen. However, immortalization additionally requires inactivation of a novel growth suppressor gene, which has recently been identified to be on the distal portion of the long arm of chromosome 6, designated SEN6. We propose that SEN6 is responsible for cellular senescence in fibroblasts and other cells.
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Affiliation(s)
- H L Ozer
- Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, Newark 07103, USA
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Li S, Baserga R. Epidermal growth factor and platelet-derived growth factor regulate the activity of the insulin-like growth factor I gene promoter. Exp Gerontol 1996; 31:195-206. [PMID: 8706788 DOI: 10.1016/0531-5565(95)02011-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The expression of insulin-like growth factor I (IGF-I) is regulated by hormones, oncogenes, and other growth factors, and is markedly decreased or even absent in senescent human diploid fibroblasts. In previous articles, we have reported that the SV40 large T antigen increases the production of IGF-I and that the expression of the IGF-I gene is negatively regulated by an E2F binding site in the IGF-I promoter. We have now investigated the activity of the IGF-I promoter, in response to stimulation of cells by either PDGF or EGF. Both growth factors stimulate the activity of the IGF-I promoter, indicating that they regulate the levels of expression of IGF-I. When the E2F binding sequence in the IGF-I promoter is mutated, the IGF-I promoter is constitutively active and no longer responds to the action of growth factors.
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Affiliation(s)
- S Li
- Jefferson Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Abstract
The loss of replicative capacity in vitro of normal human diploid fibroblasts is a model for studying molecular changes that accompany both regulated growth control and cellular senescence. We describe the molecular phenotype of senescent fibroblasts in terms of markers that are altered with proliferative decline. We describe these markers by analyzing pathways and associated mechanisms related to the responsiveness of proliferatively competent and senescent cells to growth signals including changes in the extracellular environment, growth factors, growth factor receptors, secondary messengers, cell-cycle progression, transcription factors, and the fidelity of DNA synthesis. There is an abundance of molecular markers for senescence in culture at every level of information transfer. Although it seems clear that some alterations in gene expression with senescence are the result of specific changes in upstream events, more global dysregulation of coordinated growth control point to as yet undefined mechanisms.
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Affiliation(s)
- V J Cristofalo
- Center for Gerontological Research, Medical College of Pennsylvania, Philadelphia 19129, USA
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Cristofalo VJ, Pignolo RJ. Cell Culture as a Model. Compr Physiol 1995. [DOI: 10.1002/cphy.cp110104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Guerne PA, Blanco F, Kaelin A, Desgeorges A, Lotz M. Growth factor responsiveness of human articular chondrocytes in aging and development. ARTHRITIS AND RHEUMATISM 1995; 38:960-8. [PMID: 7612045 DOI: 10.1002/art.1780380712] [Citation(s) in RCA: 159] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE To examine growth factor responses of human articular chondrocytes in aging and development. We have previously established a growth factor response profile for adult human articular chondrocytes and shown that transforming growth factor beta (TGF beta) is the most potent mitogen among a variety of factors tested. METHODS Chondrocytes were isolated from human articular cartilage obtained from donors ages 11-83 years and tested in primary culture for proliferative responses to serum and recombinant preparations of the major chondrocyte growth factors. Proliferation was measured by 3H-thymidine incorporation and cell counting. Skeletal maturity of the young donors was determined by radiographic assessment of Risser's index. RESULTS Chondrocytes showed a continuous age-related decline in the proliferative response to serum. Analysis of recombinant growth factors showed that with increasing donor age, there was a decrease in the levels of DNA synthesis in response to all factors tested. In chondrocytes from adult donors, there was no change in the relative potencies of the different growth factors. The decrease in the levels of DNA synthesis as measured by 3H-thymidine incorporation corresponded to a reduced rate of in vitro cell replication with increasing donor age. In addition to the quantitative changes in the proliferative responses of chondrocytes with increasing age, there was a qualitative change in the pattern of growth factor responses during development. Cells from young donors (ages 10-20) responded better to platelet-derived growth factor, AA chain homodimer (PDGF-AA) than to TGF beta 1, while the inverse pattern was seen in cells from adult donors. This decrease in the response to PDGF-AA was significantly correlated with increasing skeletal maturity. CONCLUSION Chondrocyte growth factor responsiveness shows qualitative changes during development, and after skeletal maturity, there is a profound decline in the levels of DNA synthesis and cell replication in response to the known chondrocyte growth factors.
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Okazaki R, Conover CA, Harris SA, Spelsberg TC, Riggs BL. Normal human osteoblast-like cells consistently express genes for insulin-like growth factors I and II but transformed human osteoblast cell lines do not. J Bone Miner Res 1995; 10:788-95. [PMID: 7639114 DOI: 10.1002/jbmr.5650100516] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Insulin-like growth factors I (IGF-I) and II (IGF-II) are anabolic for osteoblastic cells. Although expression of IGF-I and IGF-II mRNA has been demonstrated in rodent osteoblastic cells, little is known about IGF gene expression in human osteoblastic cell models. In this study we characterized IGF-I and -II mRNA expression in (1) normal human osteoblast-like (hOB) cells, (2) a simian virus 40 immortalized hOB (HOBIT) cell line, and (3) human osteosarcoma cell lines SaOS-2, TE-85, MG-63, and U-2. Since cross-hybridization of IGF cDNA probes with ribosomal RNA obscures detection of some of the multiple IGF transcripts in human cells, we replaced Northern analysis with the more specific ribonuclease protection assay (RPA). We also used the reverse transcriptase-polymerase chain reaction (RT-PCR) to assess whether mRNAs were present at trace levels. IGF-I mRNA expression was consistently observed in normal hOB cells only and by both RT-PCR and RPA. Among IGF-I transcript variants, Ea IGF-I mRNA was more abundant than the Eb mRNA in normal hOB cells. Trace levels of IGF-I mRNA were variably detected in SaOS-2 and U-2 osteosarcoma cells when RT-PCR was performed, but we found no IGF-I mRNA in HOBIT, TE-85, or MG-63 cells. IGF-II mRNA was expressed in normal hOB, HOBIT, TE-85, and U-2 cells as assessed by either method.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R Okazaki
- Department of Molecular Biology and Biochemistry, Mayo Clinic, Rochester, Minnesota, USA
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Affiliation(s)
- S I Rattan
- Department of Chemistry, Aarhus University, Denmark
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Pignolo RJ, Rotenberg MO, Cristofalo VJ. Alterations in contact and density-dependent arrest state in senescent WI-38 cells. In Vitro Cell Dev Biol Anim 1994; 30A:471-6. [PMID: 7952516 DOI: 10.1007/bf02631316] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Normal human WI-38 fibroblast-like cells in culture undergo a process of senescence, one feature of which is a gradual decline in proliferative capacity. As these cells reach the end of their replicative life span they exhibit decreases in the fraction of cells able to synthesize DNA, in the number of doublings per passage (constant seeding density), and in the cell harvest and saturation densities. They also display increased average cell cycle times, largely at the expense of longer G1 intervals. These alterations are accompanied by morphologic changes, including cell enlargement. Before the end of the replicative life span or phase-out, there is a highly reproducible (55/58 sublines) cell loss of approximately 50%; however, a stable population survives that can exist in a viable yet nonproliferative state for many months. This stable population maintains an extremely low saturation density, representing < 5% of that achieved by early passage cultures. Further, we show that maximum harvest densities achieved by senescent cells are lower, irrespective of seeding densities, i.e. when placed at cell densities higher than those normally achieved by senescent cultures they display a net decline in cell number. This decline continues until the cell density approximates the density that would have been achieved had the cultures been seeded at standard density (1 x 10(4) cells/cm2).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R J Pignolo
- Center for Gerontological Research, Medical College of Pennsylvania, Philadelphia 19129
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