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Moens U, Prezioso C, Pietropaolo V. Functional Domains of the Early Proteins and Experimental and Epidemiological Studies Suggest a Role for the Novel Human Polyomaviruses in Cancer. Front Microbiol 2022; 13:834368. [PMID: 35250950 PMCID: PMC8894888 DOI: 10.3389/fmicb.2022.834368] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/31/2022] [Indexed: 11/13/2022] Open
Abstract
As their name indicates, polyomaviruses (PyVs) can induce tumors. Mouse PyV, hamster PyV and raccoon PyV have been shown to cause tumors in their natural host. During the last 30 years, 15 PyVs have been isolated from humans. From these, Merkel cell PyV is classified as a Group 2A carcinogenic pathogen (probably carcinogenic to humans), whereas BKPyV and JCPyV are class 2B (possibly carcinogenic to humans) by the International Agency for Research on Cancer. Although the other PyVs recently detected in humans (referred to here as novel HPyV; nHPyV) share many common features with PyVs, including the viral oncoproteins large tumor antigen and small tumor antigen, as their role in cancer is questioned. This review discusses whether the nHPyVs may play a role in cancer based on predicted and experimentally proven functions of their early proteins in oncogenic processes. The functional domains that mediate the oncogenic properties of early proteins of known PyVs, that can cause cancer in their natural host or animal models, have been well characterized and we examined whether these functional domains are conserved in the early proteins of the nHPyVs and presented experimental evidence that these conserved domains are functional. Furthermore, we reviewed the literature describing the detection of nHPyV in human tumors.
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Affiliation(s)
- Ugo Moens
- Faculty of Health Sciences, Department of Medical Biology, University of Tromsø – The Arctic University of Norway, Tromsø, Norway
- *Correspondence: Ugo Moens,
| | - Carla Prezioso
- Microbiology of Chronic Neuro-Degenerative Pathologies, IRCSS San Raffaele Roma, Rome, Italy
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy
| | - Valeria Pietropaolo
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy
- Valeria Pietropaolo,
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2
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Hakuno F, Fukushima T, Yoneyama Y, Kamei H, Ozoe A, Yoshihara H, Yamanaka D, Shibano T, Sone-Yonezawa M, Yu BC, Chida K, Takahashi SI. The Novel Functions of High-Molecular-Mass Complexes Containing Insulin Receptor Substrates in Mediation and Modulation of Insulin-Like Activities: Emerging Concept of Diverse Functions by IRS-Associated Proteins. Front Endocrinol (Lausanne) 2015; 6:73. [PMID: 26074875 PMCID: PMC4443775 DOI: 10.3389/fendo.2015.00073] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 04/25/2015] [Indexed: 12/25/2022] Open
Abstract
Insulin-like peptides, such as insulin-like growth factors (IGFs) and insulin, induce a variety of bioactivities, such as growth, differentiation, survival, increased anabolism, and decreased catabolism in many cell types and in vivo. In general, IGFs or insulin bind to IGF-I receptor (IGF-IR) or insulin receptor (IR), activating the receptor tyrosine kinase. Insulin receptor substrates (IRSs) are known to be major substrates of receptor kinases, mediating IGF/insulin signals to direct bioactivities. Recently, we discovered that IRSs form high-molecular-mass complexes (referred to here as IRSomes) even without IGF/insulin stimulation. These complexes contain proteins (referred to here as IRSAPs; IRS-associated proteins), which modulate tyrosine phosphorylation of IRSs by receptor kinases, control IRS stability, and determine intracellular localization of IRSs. In addition, in these complexes, we found not only proteins that are involved in RNA metabolism but also RNAs themselves. Thus, IRSAPs possibly contribute to modulation of IGF/insulin bioactivities. Since it is established that disorder of modulation of insulin-like activities causes various age-related diseases including cancer, we could propose that the IRSome is an important target for treatment of these diseases.
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Affiliation(s)
- Fumihiko Hakuno
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Toshiaki Fukushima
- Laboratory of Biomedical Chemistry, Basic Life Sciences, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Department of Biological Sciences, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Kanagawa, Japan
| | - Yosuke Yoneyama
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Hiroyasu Kamei
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Atsufumi Ozoe
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Hidehito Yoshihara
- Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Daisuke Yamanaka
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Takashi Shibano
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Meri Sone-Yonezawa
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Bu-Chin Yu
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Kazuhiro Chida
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Shin-Ichiro Takahashi
- Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
- *Correspondence: Shin-Ichiro Takahashi, Laboratory of Cell Regulation, Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan,
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3
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Inhibition of Cullin-RING E3 ubiquitin ligase 7 by simian virus 40 large T antigen. Proc Natl Acad Sci U S A 2014; 111:3371-6. [PMID: 24550499 DOI: 10.1073/pnas.1401556111] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Simian virus 40 (SV40) large tumor antigen (LT) triggers oncogenic transformation by inhibition of key tumor suppressor proteins, including p53 and members of the retinoblastoma family. In addition, SV40 transformation requires binding of LT to Cullin 7 (CUL7), a core component of Cullin-RING E3 ubiquitin ligase 7 (CRL7). However, the pathomechanistic effects of LT-CUL7 interaction are mostly unknown. Here we report both in vitro and in vivo experimental evidence that SV40 LT suppresses the ubiquitin ligase function of CRL7. We show that SV40 LT, but not a CUL7 binding-deficient mutant (LT(Δ69-83)), impaired 26S proteasome-dependent proteolysis of the CRL7 target protein insulin receptor substrate 1 (IRS1), a component of the insulin and insulin-like growth factor 1 signaling pathway. SV40 LT expression resulted in the accumulation and prolonged half-life of IRS1. In vitro, purified SV40 LT reduced CRL7-dependent IRS1 ubiquitination in a concentration-dependent manner. Expression of SV40 LT, or depletion of CUL7 by RNA interference, resulted in the enhanced activation of IRS1 downstream signaling pathways phosphatidylinositol-3-kinase/AKT and Erk mitogen-activated pathway kinase, as well as up-regulation of the downstream target gene c-fos. Finally, SV40 LT-positive carcinoma of carcinoembryonic antigen 424/SV40 LT transgenic mice displayed elevated IRS1 protein levels and activation of downstream signaling. Taken together, these data suggest that SV40 LT protects IRS1 from CRL7-mediated degradation, thereby sustaining high levels of promitogenic IRS1 downstream signaling pathways.
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Contaldo C, Myers TJ, Zucchini C, Manara MC, Chiodoni C, Colombo MP, Nicoletti G, Lollini PL, Li T, Longobardi L, Scotlandi K, Spagnoli A. Expression levels of insulin receptor substrate-1 modulate the osteoblastic differentiation of mesenchymal stem cells and osteosarcoma cells. Growth Factors 2014; 32:41-52. [PMID: 24438070 DOI: 10.3109/08977194.2013.870168] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The insulin-like growth factor-1 system, including its critical mediator insulin receptor substrate-1 (IRS-1), is involved in regulating osteosarcoma (OS) cell proliferation or differentiation. The aim of this study is to define the role of IRS-1 in OS cells by assessing the contribution of IRS-1 in the differentiation of human and murine OS cell lines and mouse mesenchymal stem cells (MSCs) and found that the basal level of IRS-1 is important for the initiation of differentiation. Both down-regulation and over-expression of IRS-1 inhibited osteoblastic differentiation. In vivo studies showed that OS cells over-expressing IRS-1 have increased metastatic potential and tumor growth. The proteasome inhibitor MG-132 led to an increase in IRS-1 protein level that inhibited osteoblastic differentiation, suggesting a role for proteasomal regulation in maintaining the appropriate expression level of IRS-1. Thus, precise regulation of IRS-1 expression level is critical for determining the differentiating capacity of MSCs and OS cells, and that derangement of IRS-1 levels can be a critical step in OS transformation.
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Affiliation(s)
- Clara Contaldo
- Laboratory of Experimental Oncology, CRS Development of Molecular Therapies, Orthopaedic Rizzoli Institute , Bologna , Italy
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Hoxhaj G, Dissanayake K, MacKintosh C. Effect of IRS4 levels on PI 3-kinase signalling. PLoS One 2013; 8:e73327. [PMID: 24039912 PMCID: PMC3769281 DOI: 10.1371/journal.pone.0073327] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 07/25/2013] [Indexed: 11/20/2022] Open
Abstract
Insulin receptor substrate 1 (IRS1) and IRS2 are well-characterized adapter proteins that relay signals from receptor tyrosine kinases to downstream components of signalling pathways. In contrast, the function of IRS4 is not well understood. IRS4 overexpression has been associated with acute lymphoblastic leukaemia and subungual exostosis, while point mutations of IRS4 have been found in melanomas. Here, we show that while IRS4 expression is low in most cancer cell lines, IRS4 mRNA and protein levels are markedly elevated in certain cells including the NCI-H720, DMS114, HEK293T and HEK293AAV lines. Surprisingly, IRS4 expression was also strongly induced when HEK293 cells were infected with retroviral particles and selected under puromycin, making IRS4 expression a potential off-target effect of retroviral expression vectors. Cells with high expression of IRS4 displayed high phosphatidylinositol (3,4,5)-trisphosphate (PIP3) levels, as well as elevated Akt and p70 S6 kinase activities, even in the absence of growth factors. PI 3-kinase (PI3K) signalling in these cells depends on IRS4, even though these cells also express IRS1/2. Knockdown of IRS4 also inhibited cell proliferation in cells with high levels of IRS4. Together, these findings suggest IRS4 as a potential therapeutic target for cancers with high expression of this protein.
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Affiliation(s)
- Gerta Hoxhaj
- Medical Research Council Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Kumara Dissanayake
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Carol MacKintosh
- Medical Research Council Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
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Chan SH, Kikkawa U, Matsuzaki H, Chen JH, Chang WC. Insulin receptor substrate-1 prevents autophagy-dependent cell death caused by oxidative stress in mouse NIH/3T3 cells. J Biomed Sci 2012; 19:64. [PMID: 22788551 PMCID: PMC3430578 DOI: 10.1186/1423-0127-19-64] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Accepted: 06/27/2012] [Indexed: 11/10/2022] Open
Abstract
Background Insulin receptor substrate (IRS)-1 is associated with tumorigenesis; its levels are elevated in several human cancers. IRS-1 protein binds to several oncogene proteins. Oxidative stress and reactive oxygen species (ROS) are involved in the initiation and progression of cancers. Cancer cells produce greater levels of ROS than normal cells do because of increased metabolic stresses. However, excessive production of ROS kills cancer cells. Autophagy usually serves as a survival mechanism in response to stress conditions, but excessive induction of autophagy results in cell death. In addition to inducing necrosis and apoptosis, ROS induces autophagic cell death. ROS inactivates IRS-1 mediated signaling and reduces intracellular IRS-1 concentrations. Thus, there is a complex relationship between IRS-1, ROS, autophagy, and cancer. It is not fully understood how cancer cells grow rapidly and survive in the presence of high ROS levels. Methods and results In this study, we established mouse NIH/3T3 cells that overexpressed IRS-1, so mimicking cancers with increased IRS-1 expression levels; we found that the IRS-1 overexpressing cells grow more rapidly than control cells do. Treatment of cells with glucose oxidase (GO) provided a continuous source of ROS; low dosages of GO promoted cell growth, while high doses induced cell death. Evidence for GO induced autophagy includes increased levels of isoform B-II microtubule-associated protein 1 light chain 3 (LC3), aggregation of green fluorescence protein-tagged LC3, and increased numbers of autophagic vacuoles in cells. Overexpression of IRS-1 resulted in inhibition of basal autophagy, and reduced oxidative stress-induced autophagy and cell death. ROS decreased the mammalian target of rapamycin (mTOR)/p70 ribosomal protein S6 kinase signaling, while overexpression of IRS-1 attenuated this inhibition. Knockdown of autophagy-related gene 5 inhibited basal autophagy and diminished oxidative stress-induced autophagy and cell death. Conclusion Our results suggest that overexpression of IRS-1 promotes cells growth, inhibits basal autophagy, reduces oxidative stress-induced autophagy, and diminishes oxidative stress-mediated autophagy-dependent cell death. ROS-mediated autophagy may occur via inhibition of IRS-1/phosphatidylinositol 3-kinase/mTOR signaling. Our data afford a plausible explanation for IRS-1 involvement in tumor initiation and progression.
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Affiliation(s)
- Shih-Hung Chan
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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7
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Abstract
The family of insulin receptor substrates (IRS) consists of four proteins (IRS-1-IRS-4), which were initially characterized as typical cytosolic adaptor proteins involved in insulin receptor (IR) and insulin-like growth factor I receptor (IGF-IR) signaling. The first cloned and characterized member of the IRS family, IRS-1, has a predicted molecular weight of 132 kDa, however, as a result of its extensive serine phosphorylation it separates on a SDS gel as a band of approximately 160-185 kDa. In addition to its metabolic and growth-promoting functions, IRS-1 is also suspected to play a role in malignant transformation. The mechanism by which IRS-1 supports tumor growth is not fully understood, and the argument that IRS-1 merely amplifies the signal from the IGF-1R and/or IR requires further investigation. Almost a decade ago, we reported the presence of nuclear IRS-1 in medulloblastoma clinical samples, which express viral oncoprotein, large T-antigen of human polyomavirus JC (JCV T-antigen). This first demonstration of nuclear IRS-1 was confirmed by several other laboratories. Nuclear IRS-1 was also detected by cells expressing the SV40 T-antigen, v-Src, in immortalized fibroblasts stimulated with IGF-I, in hepatocytes, 32D cells, and in an osteosarcoma cell line. More recently, nuclear IRS-1 was detected in breast cancer cells in association with estrogen receptor alpha (ERα), and in JC virus negative medulloblastoma cells expressing estrogen receptor beta (ERβ), further implicating nuclear IRS-1 in cellular transformation. Here, we discuss how nuclear IRS-1 acting on DNA repair fidelity, transcriptional activity, and cell growth can support tumor development and progression.
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Affiliation(s)
- Krzysztof Reiss
- Neurological Cancer Research, Stanley S. Scott Cancer Center, School of Medicine, LSU Health Sciences Center, New Orleans, LA 70112, USA.
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8
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Wei X, Feng J, Hu Y. Gene expression by simian virus 40 large T antigen-induced medulloblastomas in mice. Neural Regen Res 2012; 7:932-7. [PMID: 25722678 PMCID: PMC4341289 DOI: 10.3969/j.issn.1673-5374.2012.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 03/09/2012] [Indexed: 11/18/2022] Open
Abstract
Signaling pathways known to have components with mutations in human medulloblastoma include sonic hedgehog, Wnt/beta-catenin and insulin-like growth factor. Microarray analysis was applied to examine the gene expression changes in medulloblastomas of pTet-on/pTRE-SV40Tag transgenic mice. Altogether, 14 112 genes were detectable, including 152 genes with significantly different expression levels. These genes were associated with immunity, the cell cycle, signal transduction, cytoskeleton and metabolism. To further confirm the microarray data, real-time polymerase chain reactions were used to examine the expression changes of genes related to sonic hedgehog, Wnt/beta-catenin and insulin-like growth factor signal pathways. Immunohistochemistry detected insulin receptor substrate-1 in the nuclei of brain tumor tissue cells from pTet-on/pTRE-SV40Tag transgenic mice, suggesting that SV40 large T antigen may activate the insulin-like growth factor signal pathway to promote tumorigenesis.
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Affiliation(s)
- Xiaoluan Wei
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Key Laboratory of Brain Functional Genomics, MOE & STCSM, East China Normal University, Shanghai 200062, China
| | - Jie Feng
- Shanghai Laboratory Animal Research Center, Shanghai 200032, China
| | - Yinghe Hu
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Key Laboratory of Brain Functional Genomics, MOE & STCSM, East China Normal University, Shanghai 200062, China
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9
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He Q, Ao Q, Gong Y, Zhang X. Preparation of chitosan films using different neutralizing solutions to improve endothelial cell compatibility. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2011; 22:2791-2802. [PMID: 22042456 DOI: 10.1007/s10856-011-4444-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 09/05/2011] [Indexed: 05/31/2023]
Abstract
The development of chitosan-based constructs for application in large-size defects or highly vascularized tissues is still a challenging issue. The poor endothelial cell compatibility of chitosan hinders the colonization of vascular endothelial cells in the chitosan-based constructs, and retards the establishment of a functional microvascular network following implantation. The aim of the present study is to prepare chitosan films with different neutralization methods to improve their endothelial cell compatibility. Chitosan salt films were neutralized with either sodium hydroxide (NaOH) aqueous solution, NaOH ethanol solution, or ethanol solution without NaOH. The physicochemical properties and endothelial cell compatibility of the chitosan films were investigated. Results indicated that neutralization with different solutions affected the surface chemistry, swelling ratio, crystalline conformation, nanotopography, and mechanical properties of the chitosan films. The NaOH ethanol solution-neutralized chitosan film (Chi-NaOH/EtOH film) displayed a nanofiber-dominant surface, while the NaOH aqueous solution-neutralized film (Chi-NaOH/H(2)O film) and the ethanol solution-neutralized film (Chi-EtOH film) displayed nanoparticle-dominant surfaces. Moreover, the Chi-NaOH/EtOH films exhibited a higher stiffness as compared to the Chi-NaOH/H(2)O and Chi-EtOH films. Endothelial cell compatibility of the chitosan films was evaluated with a human microvascular endothelial cell line, HMEC-1. Compared with the Chi-NaOH/H(2)O and Chi-EtOH films, HMECs cultured on the Chi-NaOH/EtOH films fully spread and exhibited significantly higher levels of adhesion and proliferation, with retention of the endothelial phenotype and function. Our findings suggest that the surface nanotopography and mechanical properties contribute to determining the endothelial cell compatibility of chitosan films. The nature of the neutralizing solutions can affect the physicochemical properties and endothelial cell compatibility of chitosan films. Therefore, selection of suitable neutralization methods is highly important for the application of chitosan in tissue engineering.
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Affiliation(s)
- Qing He
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China
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10
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Deactivation of Akt by a small molecule inhibitor targeting pleckstrin homology domain and facilitating Akt ubiquitination. Proc Natl Acad Sci U S A 2011; 108:6486-91. [PMID: 21464312 DOI: 10.1073/pnas.1019062108] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The phosphatidylinositol-3,4,5-triphosphate (PIP3) binding function of pleckstrin homology (PH) domain is essential for the activation of oncogenic Akt/PKB kinase. Following the PIP3-mediated activation at the membrane, the activated Akt is subjected to other regulatory events, including ubiquitination-mediated deactivation. Here, by identifying and characterizing an allosteric inhibitor, SC66, we show that the facilitated ubiquitination effectively terminates Akt signaling. Mechanistically, SC66 manifests a dual inhibitory activity that directly interferes with the PH domain binding to PIP3 and facilitates Akt ubiquitination. A known PH domain-dependent allosteric inhibitor, which stabilizes Akt, prevents the SC66-induced Akt ubiquitination. A cancer-relevant Akt1 (e17k) mutant is unstable, making it intrinsically sensitive to functional inhibition by SC66 in cellular contexts in which the PI3K inhibition has little inhibitory effect. As a result of its dual inhibitory activity, SC66 manifests a more effective growth suppression of transformed cells that contain a high level of Akt signaling, compared with other inhibitors of PIP3/Akt pathway. Finally, we show the anticancer activity of SC66 by using a soft agar assay as well as a mouse xenograft tumor model. In conclusion, in this study, we not only identify a dual-function Akt inhibitor, but also demonstrate that Akt ubiquitination could be chemically exploited to effectively facilitate its deactivation, thus identifying an avenue for pharmacological intervention in Akt signaling.
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Abstract
Over 50 years of polyomavirus research has produced a wealth of insights into not only general biologic processes in mammalian cells, but also, how conditions can be altered and signaling systems tweaked to produce transformation phenotypes. In the past few years three new members (KIV, WUV, and MCV) have joined two previously known (JCV and BKV) human polyomaviruses. In this review, we present updated information on general virologic features of these polyomaviruses in their natural host, concentrating on the association of MCV with human Merkel cell carcinoma. We further present a discussion on advances made in SV40 as the prototypic model, which has and will continue to inform our understanding about viruses and cancer.
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Affiliation(s)
- Ole Gjoerup
- Cancer Virology Program, Hillman Cancer Research Pavilion, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
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12
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Cheng J, DeCaprio JA, Fluck MM, Schaffhausen BS. Cellular transformation by Simian Virus 40 and Murine Polyoma Virus T antigens. Semin Cancer Biol 2009; 19:218-28. [PMID: 19505649 PMCID: PMC2694755 DOI: 10.1016/j.semcancer.2009.03.002] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 03/19/2009] [Accepted: 03/20/2009] [Indexed: 01/09/2023]
Abstract
Simian Virus 40 (SV40) and Mouse Polyoma Virus (PY) are small DNA tumor viruses that have been used extensively to study cellular transformation. The SV40 early region encodes three tumor antigens, large T (LT), small T (ST) and 17KT that contribute to cellular transformation. While PY also encodes LT and ST, the unique middle T (MT) generates most of the transforming activity. SV40 LT mediated transformation requires binding to the tumor suppressor proteins Rb and p53 in the nucleus and ST binding to the protein phosphatase PP2A in the cytoplasm. SV40 LT also binds to several additional cellular proteins including p300, CBP, Cul7, IRS1, Bub1, Nbs1 and Fbxw7 that contribute to viral transformation. PY MT transformation is dependent on binding to PP2A and the Src family protein tyrosine kinases (PTK) and assembly of a signaling complex on cell membranes that leads to transformation in a manner similar to Her2/neu. Phosphorylation of MT tyrosine residues activates key signaling molecules including Shc/Grb2, PI3K and PLCgamma1. The unique contributions of SV40 LT and ST and PY MT to cellular transformation have provided significant insights into our understanding of tumor suppressors, oncogenes and the process of oncogenesis.
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Affiliation(s)
- Jingwei Cheng
- Department of Medical Oncology, Dana-Farber Cancer Institute; Department of Medicine, Brigham and Women’s Hospital; and Harvard Medical School, Boston, MA 02115
| | - James A. DeCaprio
- Department of Medical Oncology, Dana-Farber Cancer Institute; Department of Medicine, Brigham and Women’s Hospital; and Harvard Medical School, Boston, MA 02115
- Center for Applied Cancer Science, Dana-Farber Cancer Institute, Boston, MA 02115
| | - Michele M. Fluck
- Department of Microbiology and Molecular Genetics, Interdepartmental Program in Cell and Molecular Biology, Michigan State University, East Lansing, MI 48824
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The insulin receptor substrate-1: A biomarker for cancer? Exp Cell Res 2009; 315:727-32. [DOI: 10.1016/j.yexcr.2008.09.017] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 09/23/2008] [Accepted: 09/23/2008] [Indexed: 01/13/2023]
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14
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Pipas JM. SV40: Cell transformation and tumorigenesis. Virology 2008; 384:294-303. [PMID: 19070883 DOI: 10.1016/j.virol.2008.11.024] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Accepted: 11/18/2008] [Indexed: 10/21/2022]
Abstract
The story of SV40-induced tumorigenesis and cellular transformation is intimately entwined with the development of modern molecular biology. Because SV40 and other viruses have small genomes and are relatively easy to manipulate in the laboratory, they offered tractable systems for molecular analysis. Thus, many of the early efforts to understand how eukaryotes replicate their DNA, regulate expression of their genes, and translate mRNA were focused on viral systems. The discovery that SV40 induces tumors in certain laboratory animals and transforms many types of cultured cells offered the first opportunity to explore the molecular basis for cancer. The goal of this article is to highlight some of the experiments that have led to our current view of SV40-induced transformation and to provide some context as to how they contributed to basic research in molecular biology and to our understanding of cancer.
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Affiliation(s)
- James M Pipas
- Department of Biological Sciences, University of Pittsburgh, PA 15260, USA.
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15
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Shimwell NJ, Martin A, Bruton RK, Blackford AN, Sedgwick GG, Gallimore PH, Turnell AS, Grand RJA. Adenovirus 5 E1A is responsible for increased expression of insulin receptor substrate 4 in established adenovirus 5-transformed cell lines and interacts with IRS components activating the PI3 kinase/Akt signalling pathway. Oncogene 2008; 28:686-97. [DOI: 10.1038/onc.2008.417] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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16
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Cancer cell-derived clusterin modulates the phosphatidylinositol 3'-kinase-Akt pathway through attenuation of insulin-like growth factor 1 during serum deprivation. Mol Cell Biol 2008; 28:4285-99. [PMID: 18458059 DOI: 10.1128/mcb.01240-07] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cancer cells in their respective microenvironments must endure various growth-constraining stresses. Under these conditions, the cancer cell-derived factors are thought to modulate the signaling pathways between cell growth and dormancy. Here, we describe a cancer cell-derived regulatory system that modulates the phosphatidylinositol 3'-kinase (PI3K)-Akt pathway under serum deprivation stress. Through the use of biochemical purification, we reveal that cancer cell-secreted insulin-like growth factor 1 (IGF-1) and clusterin, an extracellular stress protein, constitute this regulatory system. We show that secreted clusterin associates with IGF-1 and inhibits its binding to the IGF-1 receptor and hence negatively regulates the PI3K-Akt pathway during serum deprivation. This inhibitory function of clusterin appears to prefer IGF-1, as it fails to exert any effects on epidermal growth factor signaling. We demonstrate furthermore that the constitutive activation of oncogenic signaling downstream of IGF-1 confers insensitivity to the inhibitory effects of clusterin. Thus, the interplay between cancer cell-derived clusterin and IGF-1 may dictate the outcome of cell growth and dormancy during tumorigenic progression.
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17
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Interaction between simian virus 40 large T antigen and insulin receptor substrate 1 is disrupted by the K1 mutation, resulting in the loss of large T antigen-mediated phosphorylation of Akt. J Virol 2008; 82:4521-6. [PMID: 18305032 DOI: 10.1128/jvi.02365-07] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The cellular kinase Akt is a key controller of cellular metabolism, growth, and proliferation. Many viruses activate Akt due to its beneficial effects on viral replication. We previously showed that wild-type (WT) simian virus 40 (SV40) large T antigen (TAg) inhibits apoptosis via the activation of PI3K/Akt signaling. Here we show that WT TAg expressed from recombinant adenoviruses in U2OS cells induced the phosphorylation of Akt at both T308 and S473. In contrast, Akt phosphorylation was eliminated by the K1 mutation (E107K) within the retinoblastoma protein (Rb) binding motif of TAg. This suggested that Akt phosphorylation may depend on TAg binding to Rb or one of its family members. However, in Rb-negative SAOS2 cells depleted of p107 and p130 by using small hairpin RNAs (shRNAs), WT TAg still mediated Akt phosphorylation. These results suggested that the K1 mutation affects another TAg function. WT-TAg-mediated phosphorylation of Akt was inhibited by a PI3K inhibitor, suggesting that the effects of TAg originated upstream of PI3K; thus, we examined the requirement for insulin receptor substrate 1 (IRS1), which binds and activates PI3K. Depletion of IRS1 by shRNAs abolished the WT-TAg-mediated phosphorylation of Akt. Immunoprecipitation studies showed that the known interaction between TAg and IRS1 is significantly weakened by the K1 mutation. These data indicate that the K1 mutation disrupts not only Rb binding but also IRS1 binding, contributing to the loss of activation of PI3K/Akt signaling.
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18
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Sun Q, Wei X, Feng J, Zhang R, Shen Q, Dong J, Jin Y, Dong S, Li H, Hu Y. Involvement of insulin-like growth factor-insulin receptor signal pathway in the transgenic mouse model of medulloblastoma. Cancer Sci 2008; 99:234-40. [PMID: 18271920 PMCID: PMC11158198 DOI: 10.1111/j.1349-7006.2007.00679.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A transgenic mouse model expressing Simian virus 40 T-antigen (SV40Tag) under the control of a tetracycline system was generated. In this model, a cerebellar tumor was developed after doxycycline hydrochloride treatment. Real time-polymerase chain reaction and immunohistochemistry results indicated that the SV40Tag gene was expressed in the tumor. Pathological analysis showed that the tumor belonged to medulloblastoma. Further molecular characterization of the tumor demonstrated that the insulin-like growth factor (IGF) signaling pathway was activated. We also found that the SV40Tag could bind and translocate insulin receptor substrate 1 into the nucleus in primary cultured tumor cells. The interaction between the IGF pathway and SV40Tag may contribute to the process of malignant transformation in medulloblastoma. This transgenic animal model provides an important tool for studies on the signal pathways involved in the preneoplastic process in medulloblastoma and could help to identify therapeutic targets for brain tumors.
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Affiliation(s)
- Qiang Sun
- Key Laboratory of Brain Functional Genomics, Shanghai Institute of Brain Functional Genomics, East China Normal University, 200062, Shanghai, China
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19
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Shen Q, Sun Q, Wei X, Dong J, Zhang R, Wu P, Jin Y, Feng J, Li H, Hu Y. Generation and characterization of islet cell tumor in pTet-on/pTRE-SV40Tag double-transgenic mice model. J Biosci Bioeng 2007; 104:14-21. [PMID: 17697978 DOI: 10.1263/jbb.104.14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Accepted: 04/05/2007] [Indexed: 01/04/2023]
Abstract
A line of double-transgenic mice that develop neoplasms arising primarily in the pancreas was established. In these mice, the oncogene SV40 T antigen (Tag) was detected in the pancreas with and without the control of Tet-on system. The transgenic mice that developed pancreatic tumors as early as 20 weeks of age showed hypoglycemia on a blood glucose test. Pathological and immunohistochemical characterizations demonstrated that the tumors belonged to neuroendocrine neoplasms arising from pancreatic islets. A change in IGFs/IGF-1R signaling pathway was detected using real-time PCR analysis. A potential association between the IGFs/IGF-1R system and SV40Tag was studied to further explain the cancerogenesis of the double-transgenic mice by Western blot analysis and immunoprecipitation experiments. The results suggest that a Tag transgenic mice model could be used to study the molecular mechanism of the tumorigenesis of islets.
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Affiliation(s)
- Qian Shen
- Key Lab of Brain Functional Genomics, MOE & STCSM, Shanghai Institute of Brain Functional Genomics, East China Normal University, Shanghai, PR China
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20
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Dearth RK, Cui X, Kim HJ, Kuiatse I, Lawrence NA, Zhang X, Divisova J, Britton OL, Mohsin S, Allred DC, Hadsell DL, Lee AV. Mammary tumorigenesis and metastasis caused by overexpression of insulin receptor substrate 1 (IRS-1) or IRS-2. Mol Cell Biol 2006; 26:9302-14. [PMID: 17030631 PMCID: PMC1698542 DOI: 10.1128/mcb.00260-06] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Insulin receptor substrates (IRSs) are signaling adaptors that play a major role in the metabolic and mitogenic actions of insulin and insulin-like growth factors. Reports have recently noted increased levels, or activity, of IRSs in many human cancers, and some have linked this to poor patient prognosis. We found that overexpressed IRS-1 was constitutively phosphorylated in vitro and in vivo and that transgenic mice overexpressing IRS-1 or IRS-2 in the mammary gland showed progressive mammary hyperplasia, tumorigenesis, and metastasis. Tumors showed extensive squamous differentiation, a phenotype commonly seen with activation of the canonical beta-catenin signaling pathway. Consistent with this, IRSs were found to bind beta-catenin in vitro and in vivo. IRS-induced tumorigenesis is unique, given that the IRSs are signaling adaptors with no intrinsic kinase activity, and this supports a growing literature indicating a role for IRSs in cancer. This study defines IRSs as oncogene proteins in vivo and provides new models to develop inhibitors against IRSs for anticancer therapy.
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Affiliation(s)
- Robert K Dearth
- Breast Cancer, Baylor College of Medicine and Methodist Hospital, Department of Medicine, Houston, TX 77030, USA
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21
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Trojanek J, Ho T, Croul S, Wang JY, Chintapalli J, Koptyra M, Giordano A, Khalili K, Reiss K. IRS-1-Rad51 nuclear interaction sensitizes JCV T-antigen positive medulloblastoma cells to genotoxic treatment. Int J Cancer 2006; 119:539-48. [PMID: 16572421 DOI: 10.1002/ijc.21828] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The large T-antigen from human polyomavirus JC (JCV T-antigen) is suspected to play a role in malignant transformation. Previously, we reported that JCV T-antigen requires the presence of a functional insulin-like growth factor I receptor (IGF-IR) for transformation of fibroblasts and for survival of medulloblastoma cell lines; that IGF-IR is phosphorylated in medulloblastoma biopsies and that JCV T-antigen inhibits homologous recombination-directed DNA repair, causing accumulation of mutations. Here we are evaluating whether JCV T-antigen positive and negative mouse medulloblastoma cell lines, which significantly differ in their tumorigenic properties, are also different in their abilities to repair double strand breaks of DNA (DSBs). Our results show that despite much stronger tumorigenic potential, JCV T-antigen positive medulloblastoma cells are more sensitive to genotoxic agents (cisplatin and gamma-irradiation). Subsequent analysis of DNA repair of DSBs indicated that homologous recombination-directed DNA repair (HRR) was selectively attenuated in JCV T-antigen positive medulloblastoma cells. JCV T-antigen did not affect HRR directly. In the presence of JCV T-antigen, insulin receptor substrate 1 (IRS-1) translocated to the nucleus where it co-localized with Rad51, possibly attenuating HRR.
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Affiliation(s)
- Joanna Trojanek
- Center for Neurovirology, Department of Neuroscience, Temple University, Philadelphia, PA 19122, USA
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22
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Taniguchi CM, Emanuelli B, Kahn CR. Critical nodes in signalling pathways: insights into insulin action. Nat Rev Mol Cell Biol 2006; 7:85-96. [PMID: 16493415 DOI: 10.1038/nrm1837] [Citation(s) in RCA: 1938] [Impact Index Per Article: 107.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Physiologically important cell-signalling networks are complex, and contain several points of regulation, signal divergence and crosstalk with other signalling cascades. Here, we use the concept of 'critical nodes' to define the important junctions in these pathways and illustrate their unique role using insulin signalling as a model system.
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Affiliation(s)
- Cullen M Taniguchi
- Joslin Diabetes Center, One Joslin Place, Boston, Massachusetts 02215, USA
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23
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Trojanek J, Croul S, Ho T, Wang JY, Darbinyan A, Nowicki M, Del Valle L, Skorski T, Khalili K, Reiss K. T-antigen of the human polyomavirus JC attenuates faithful DNA repair by forcing nuclear interaction between IRS-1 and Rad51. J Cell Physiol 2006; 206:35-46. [PMID: 15965906 DOI: 10.1002/jcp.20425] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
JC polyomavirus (JCV), which infects 90% of the human population, is detectable in human tumors. Its early protein, JCV T-antigen, transforms cells in vitro and is tumorigenic in experimental animals. Although T-antigen-mediated transformation involves genetic alterations of the affected cells, the mechanism underlying this genomic instability is not known. We show that JCV T-antigen inhibits homologous recombination DNA repair (HRR), which results in an accumulation of mutations. T-antigen does not operate directly but utilizes a cytosolic molecule, insulin receptor substrate 1 (IRS-1). Following T-antigen-mediated nuclear translocation, IRS-1 binds Rad51 at the site of damaged DNA. This T-antigen-mediated inhibition of HRR does not function in cells lacking IRS-1, and can be reproduced in the absence of T-antigen by IRS-1 with artificial nuclear localization signal. Our observations define a new mechanism by which viral protein utilizes cytosolic molecule to inhibit faithful DNA repair, and suggest how polyomaviruses could compromise stability of the genome. (c) 2005 Wiley-Liss, Inc.
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Affiliation(s)
- Joanna Trojanek
- Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, Biology Life Science Building, Philadelphia, Pennsylvania 19122, USA
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24
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White MK, Khalili K. Expression of JC virus regulatory proteins in human cancer: potential mechanisms for tumourigenesis. Eur J Cancer 2005; 41:2537-48. [PMID: 16219459 DOI: 10.1016/j.ejca.2005.08.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
JC virus (JCV) is a human polyomavirus that is the etiologic agent of the fatal demyelinating disease of the central nervous system known as progressive multifocal leukoencephalopathy (PML). JCV is also linked to some tumours of the brain and other organs as evidenced by the presence of JCV DNA sequences and the expression of viral proteins in clinical samples. Since JCV is highly oncogenic in experimental animals and transforms cells in culture, it is possible that JCV contributes to the malignant phenotype of human tumours with which it is associated. JCV encodes three non-capsid regulatory proteins: large T-antigen, small t-antigen and agnoprotein that interact with a number of cellular target proteins and interfere with certain normal cellular functions. In this review, we discuss how JCV proteins deregulate signalling pathways especially ones pertaining to transcriptional regulation and cell cycle control. These effects may be involved in the progression of JCV-associated tumours and may represent potential therapeutic targets.
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Affiliation(s)
- Martyn K White
- Center for Neurovirology, Department of Neuroscience, Temple University School of Medicine, 1900 North 12th Street, MS 015-96, Room 203, Philadelphia, PA 19122, USA
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25
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DeAngelis T, Chen J, Wu A, Prisco M, Baserga R. Transformation by the simian virus 40 T antigen is regulated by IGF-I receptor and IRS-1 signaling. Oncogene 2005; 25:32-42. [PMID: 16170362 DOI: 10.1038/sj.onc.1209013] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Previous work has shown that the Simian Virus 40 T antigen (T antigen) cannot transform mouse embryo fibroblasts (MEFs) that do not express the type 1 insulin-like growth factor receptor (IGF-IR). We have now investigated the mechanism(s) by which the transforming activity of T antigen is affected by IGF-IR signaling. We demonstrate that transformation by T antigen of MEFs and several other cell lines requires an insulin receptor substrate-1 (IRS-1) phosphorylated on tyrosines. If IRS-1 is not expressed, or is serine phosphorylated or otherwise inactive, T antigen fails to transform cells in culture. For instance, while T antigen cannot transform 32D myeloid cells (that do not express IRS-1), its transforming activity is restored by the expression of a wild-type IRS-1, but not of an IRS-1 mutated at the PI3K binding sites. The importance of IRS-1 activation of PI3K in T-antigen transformation is supported by the finding that a constitutively activated p110 subunit of PI3K, a target of IRS-1, overcomes the inability of T antigen to transform MEFs with a serine phosphorylated IRS-1. Taken together, these results indicate that the IRS-1/PI3K signaling is one of the mechanisms regulating transformation by the SV40 T antigen. We propose that the requirement for a tyrosyl-phosphorylated IRS-1 provides a mechanism to explain the failure of T antigen to transform MEFs with deleted IGF-IR genes.
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MESH Headings
- Agar/chemistry
- Animals
- Antigens, Polyomavirus Transforming/chemistry
- Antigens, Polyomavirus Transforming/metabolism
- Antigens, Viral, Tumor/chemistry
- Binding Sites
- Blotting, Western
- Breast Neoplasms/metabolism
- Cell Line
- Cell Line, Transformed
- Cell Survival
- Cell Transformation, Neoplastic
- Cells, Cultured
- Fibroblasts/metabolism
- Gene Deletion
- Insulin Receptor Substrate Proteins
- Mice
- Mutation
- Neurons/metabolism
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphoproteins/metabolism
- Phosphorylation
- Pol1 Transcription Initiation Complex Proteins/metabolism
- RNA/chemistry
- RNA, Ribosomal/chemistry
- Receptor, IGF Type 1/metabolism
- Ribosomes/metabolism
- Serine/chemistry
- Signal Transduction
- Time Factors
- Transfection
- Tyrosine/chemistry
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Affiliation(s)
- T DeAngelis
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
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26
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Abstract
This review examines the rationale for targeting the insulin-like growth factor (IGF)-I receptor in the therapy of human tumours and their metastases. The rationale is based on two crucial findings: 1) in experimental animals, normal cells are only partially affected by the deletion of the IGF-I receptor, whereas tumour cells undergo apoptosis when the IGF-I receptor is downregulated; and 2) cells with a deleted IGF-I receptor are refractory to transformation by viral and cellular oncogenes. This review focuses on the mechanisms underlying the experimental findings, and discusses the possibility of extrapolating the results obtained in animals to the cure of human tumours.
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Affiliation(s)
- Renato Baserga
- Thomas Jefferson University, Kimmel Cancer Center, 233 S. 10th Street, 624 BLSB, Philadelphia, PA 19107, USA.
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27
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Reiss K, Khalili K, Giordano A, Trojanek J. JC virus large T-antigen and IGF-I signaling system merge to affect DNA repair and genomic integrity. J Cell Physiol 2005; 206:295-300. [PMID: 15991250 DOI: 10.1002/jcp.20455] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The progression of cancer is often associated with genomic instability, which may develop as a result of compromised defense mechanisms responsible for the maintenance of chromosomal integrity. These include defects in telomere preservation, chromosomal segregation, and DNA repair. In this review, we discuss molecular interactions between viral and cellular signaling components, which interfere with DNA repair mechanisms, and possibly contribute to the development of a mutagenic phenotype. Our studies indicate that large T-antigen from the human polyomavirus JC (JCV T-antigen) inhibits homologous recombination directed DNA repair (HRR)-causing accumulation of mutations in the affected cells (JCP 2005, in press). Surprisingly, T-antigen does not operate directly, but utilizes insulin receptor substrate 1 (IRS-1), which is the major signaling molecule for insulin-like growth factor I receptor (IGF-IR). Following T-antigen-mediated nuclear translocation, IRS-1 binds Rad51 at the site of damaged DNA. This T-antigen-mediated inhibition of HRR does not function in cells lacking IRS-1, and can be reproduced in the absence of T-antigen by IRS-1 with an artificial nuclear localization signal. The interplay described between the IGF-IR signaling system and JCV T-antigen in the process of DNA repair could be relevant, since nearly 90% of the human population is seropositive for JC virus, JCV T-antigen transforms cells in vitro, is tumorigenic in experimental animals, and the presence of JC virus has been shown in an increasing number of biopsies of human cancer.
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Affiliation(s)
- Krzysztof Reiss
- Center for Neurovirology and Cancer Biology, Temple University, 1900 North 12th Street, Biology Life Science Building, Philadelphia, Pennsylvania 19122, USA.
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28
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White MK, Gordon J, Reiss K, Del Valle L, Croul S, Giordano A, Darbinyan A, Khalili K. Human polyomaviruses and brain tumors. ACTA ACUST UNITED AC 2005; 50:69-85. [PMID: 15982744 DOI: 10.1016/j.brainresrev.2005.04.007] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Revised: 04/12/2005] [Accepted: 04/21/2005] [Indexed: 12/25/2022]
Abstract
Polyomaviruses are DNA tumor viruses with small circular genomes. Three polyomaviruses have captured attention with regard to their potential role in the development of human brain tumors: JC virus (JCV), BK virus (BKV), and simian vacuolating virus 40 (SV40). JCV is a neurotropic polyomavirus that is the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system occurring mainly in AIDS patients. BKV is the causative agent of polyomavirus-associated nephropathy (PVN) which occurs after renal transplantation when BKV reactivates from a latent state during immunosuppressive therapy to cause allograft failure. SV40, originating in rhesus monkeys, gained notoriety when it entered the human population via contaminated polio vaccines. All three viruses are highly oncogenic when injected into the brain of experimental animals. Reports indicate that these viruses, especially JCV, are associated with brain tumors and other cancers in humans as evidenced from the analysis of clinical samples for the presence of viral DNA sequences and expression of viral proteins. Human polyomaviruses encode three non-capsid regulatory proteins: large T-antigen, small t-antigen, and agnoprotein. These proteins interact with a number of cellular target proteins to exert effects that dysregulate pathways involved in the control of various host cell functions including the cell cycle, DNA repair, and others. In this review, we describe the three polyomaviruses, their abilities to cause brain and other tumors in experimental animals, the evidence for an association with human brain tumors, and the latest findings on the molecular mechanisms of their actions.
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Affiliation(s)
- Martyn K White
- Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, 1900 North 12th Street, 015-96, Room 203, Philadelphia, PA 19122, USA
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29
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Vultur A, Arulanandam R, Turkson J, Niu G, Jove R, Raptis L. Stat3 is required for full neoplastic transformation by the Simian Virus 40 large tumor antigen. Mol Biol Cell 2005; 16:3832-46. [PMID: 15917293 PMCID: PMC1182320 DOI: 10.1091/mbc.e04-12-1104] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
To investigate the role of Stat3 (signal transducer and activator of transcription-3) in neoplastic transformation by the Large Tumor antigen of Simian Virus 40 (TAg), murine fibroblasts were rendered deficient in Stat3 activity through expression of a Stat3-specific siRNA or a Cre-loxP recombination system. The results demonstrate that growth rate, formation of foci overgrowing a monolayer of normal cells and colony formation in soft agar were dramatically reduced in Stat3-deficient cells. In addition, TAg expression led to increased Stat3 tyrosine phosphorylation, DNA binding, and transcriptional activity, suggesting that Stat3 is required for TAg-mediated neoplasia. Stat3 activation was prevented by blocking the binding of TAg to pRb (retinoblastoma-susceptibility gene product), whereas genetic ablation of pRb increased Stat3 activity, suggesting that pRb inactivation by TAg might be responsible for the observed Stat3 activation. Stat3 activation by TAg was suppressed after inhibition of c-Src, JAKs or the insulin-like growth factor receptor. On the other hand, targeted disruption of the Fer kinase or pharmacological inhibition of Abl had no effect. Inhibition of Src activity led to Stat3 down-regulation as well as apoptosis of sparsely growing, TAg-transformed cells. However, Src inhibition was relatively ineffective in confluent cells, consistent with previous results indicating that cell to cell adhesion activates Stat3 by a Src-independent mechanism. Direct Stat3 inhibition on the other hand induced apoptosis very effectively in confluent cells, which could have significant therapeutic implications. Taken together, our results suggest that Stat3 is an important component of a pathway emanating from TAg and leading to neoplastic conversion.
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Affiliation(s)
- Adina Vultur
- Department of Microbiology and Immunology, Queen's University, Kingston, Ontario K7L 3N6, Canada
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30
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Wu A, Tu X, Prisco M, Baserga R. Regulation of Upstream Binding Factor 1 Activity by Insulin-like Growth Factor I Receptor Signaling. J Biol Chem 2005; 280:2863-72. [PMID: 15533945 DOI: 10.1074/jbc.m406138200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The upstream binding factor 1 (UBF1) is one of the proteins in a complex that regulates the activity of RNA polymerase I, which controls the rate of ribosomal RNA (rRNA) synthesis. We have shown previously that insulin receptor substrate-1 (IRS-1) can translocate to the nuclei and nucleoli of cells and bind UBF1. We report here that activation of the type I insulin-like growth factor receptor (IGF-IR) by IGF-I increases transcription from the ribosomal DNA (rDNA) promoter in both myeloid cells and mouse fibroblasts. The increased activity of the rDNA promoter is accompanied by increased phosphorylation of UBF1, a requirement for UBF1 activation. Phosphorylation occurs on a number of UBF1 peptides, most prominently on the highly acidic, serine-rich C terminus. In myeloid cells (but not in mouse embryo fibroblasts) IRS-1 signaling stabilizes the levels of UBF1 protein. These findings demonstrate that IGF-IR signaling can increase the activity of UBF1 and transcription from the rDNA promoter, providing one explanation for the reported effects of the IGF/IRS-1 axis on cell and body size in animals and cells in culture.
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MESH Headings
- 3T3 Cells
- Animals
- Blotting, Northern
- Blotting, Western
- Cell Differentiation
- Cell Nucleolus/metabolism
- Cell Nucleus/metabolism
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/metabolism
- Exons
- Fibroblasts/metabolism
- Gene Expression Regulation
- Gene Expression Regulation, Developmental
- Mice
- Mutation
- Peptides/chemistry
- Phosphorylation
- Phosphotyrosine/chemistry
- Pol1 Transcription Initiation Complex Proteins/biosynthesis
- Pol1 Transcription Initiation Complex Proteins/genetics
- Promoter Regions, Genetic
- Protein Binding
- Protein Structure, Tertiary
- RNA, Messenger/metabolism
- RNA, Ribosomal/metabolism
- Receptor, IGF Type 1/metabolism
- Ribosomes/chemistry
- Ribosomes/metabolism
- Time Factors
- Transcription, Genetic
- Trypsin/pharmacology
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Affiliation(s)
- An Wu
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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31
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Liu M, Prisco M, Drakas R, Searles D, Baserga R. 24p3 in differentiation of myeloid cells. J Cell Physiol 2005; 205:302-9. [PMID: 15895393 DOI: 10.1002/jcp.20400] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
24p3 is a secreted lipocalin that has been variously related to apoptosis, proliferation, and the neutrophil lineage of blood cells. We have investigated the expression of 24p3 mRNA and protein in myeloid cell lines induced to differentiate by insulin-like growth factor 1 (IGF-1) and the granulocytic-colony simulating factor (G-CSF). Both these growth factors, which cause myeloid cells to differentiate into granulocytes, induced a marked increase in the expression of both 24p3 protein and mRNA. The mRNA especially appeared early after the cells were induced with either IGF-1 or G-CSF, at a time when the cells were still proliferating and are morphologically undifferentiated. 24p3 can be considered an early marker of granulocytic differentiation.
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Affiliation(s)
- Mingli Liu
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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32
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White MK, Khalili K. Polyomaviruses and human cancer: molecular mechanisms underlying patterns of tumorigenesis. Virology 2004; 324:1-16. [PMID: 15183048 DOI: 10.1016/j.virol.2004.03.025] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Accepted: 03/31/2004] [Indexed: 12/18/2022]
Abstract
Polyomaviruses are DNA tumor viruses with small circular genomes encoding only six proteins including three structural capsid proteins. Despite this simplicity, our understanding of the mechanisms of polyomavirus-mediated tumorigenesis is far from complete. The archetypal primate polyomavirus, SV40, was isolated more than 40 years ago and has been used extensively as a model system for the study of basic eukaryotic cellular processes such as DNA replication and transcription. Two human polyomaviruses have been isolated from clinical samples: JC virus (JCV) and BK virus (BKV). In this review, SV40, JCV, and BKV will be compared based on what is known about their molecular biology from experiments performed in vitro, in cell culture and in laboratory animals. The association of these viruses with clinical tumors is discussed along with the possible roles of these polyomaviruses in the etiology of human malignant disease.
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Affiliation(s)
- Martyn K White
- Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, Philadelphia, PA 19122, USA.
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Maiorana A, Tu X, Cheng G, Baserga R. Role of pescadillo in the transformation and immortalization of mammalian cells. Oncogene 2004; 23:7116-24. [PMID: 15273728 DOI: 10.1038/sj.onc.1207916] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The murine and human homologs of the zebrafish pescadillo protein (Pes1 and PES1, respectively) play important roles in ribosome biogenesis and DNA replication. We investigated the effect of Pes1 on the growth of mouse embryo (3T3-like) fibroblasts and conditionally immortalized human fibroblasts expressing the SV40 T antigen (AR5 cells). Increased expression of Pes1 causes transformation of mouse and human fibroblasts in culture (colony formation in soft agar). Although Pes1 can replace the SV40 T antigen in inducing colony formation in soft agar, it cannot substitute the T antigen in the immortalization of human fibroblasts, indicating that it distinguishes between the two functions. As the biological effects of Pes1 are similar to those of the insulin receptor substrate-1 (IRS-1), we investigated the interactions of Pes1 with IRS-1 itself and with the SV40 T antigen. The Pes1 protein (which localizes to the nuclei and nucleoli of cells) interacts with both IRS-1 and the SV40 T antigen, and markedly decreases the interaction of T antigen with p53. Taken together, these results suggest mechanisms for the ability of Pes1 to transform cells, and its failure to immortalize them.
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Affiliation(s)
- Arianna Maiorana
- Kimmel Cancer Center, Thomas Jefferson University, 233 S. 10th Street, 624 BLSB, Philadelphia, PA 19107, USA
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Wu A, Sciacca L, Baserga R. Nuclear translocation of insulin receptor substrate-1 by the insulin receptor in mouse embryo fibroblasts. J Cell Physiol 2003; 195:453-60. [PMID: 12704655 DOI: 10.1002/jcp.10261] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Translocation of the insulin receptor substrate-1 (IRS-1) to the nuclei has been reported to occur in cells stimulated by insulin-like growth factor-1 (IGF-I) or expressing certain viral and cellular oncogenes. We show here that insulin can also induce nuclear translocation of IRS-1 in mouse embryo fibroblasts (MEF), that do not express the type 1 insulin-like growth factor receptor (IGF-IR). Only the A isoform of the insulin receptor (IR) can induce IRS-1 nuclear translocation, which is significant when the receptor is over-expressed. At physiological receptor levels, translocation occurs only in a fraction of cells, and only at high concentrations of ligand.
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Affiliation(s)
- An Wu
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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35
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Sun H, Tu X, Prisco M, Wu A, Casiburi I, Baserga R. Insulin-like growth factor I receptor signaling and nuclear translocation of insulin receptor substrates 1 and 2. Mol Endocrinol 2003; 17:472-86. [PMID: 12554758 DOI: 10.1210/me.2002-0276] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The insulin receptor substrate 1 (IRS-1) can translocate to the nuclei and nucleoli of several types of cells. Nuclear translocation can be induced by an activated insulin-like growth factor 1 receptor (IGF-IR), and by certain oncogenes, such as the Simian virus 40 T antigen and v-src. We have asked whether IRS-2 could also translocate to the nuclei. In addition, we have studied the effects of functional mutations in the IGF-IR on nuclear translocation of IRS proteins. IRS-2 translocates to the nuclei of mouse embryo fibroblasts expressing the IGF-IR, but, at variance with IRS-1, does not translocate in cells expressing the Simian virus 40 T antigen. Mutations in the tyrosine kinase domain of the IGF-IR abrogate translocation of the IRS proteins. Other mutations in the IGF-IR, which do not interfere with its mitogenicity but inhibit its transforming capacity, result in a decrease in translocation, especially to the nucleoli. Nuclear IRS-1 and IRS-2 interact with the upstream binding factor, which is a key regulator of RNA polymerase I activity and, therefore, rRNA synthesis. In 32D cells, wild-type, but not mutant, IRS-1 causes a significant activation of the ribosomal DNA promoter. The interaction of nuclear IRS proteins with upstream binding factor 1 constitutes the first direct link of these proteins with the ribosomal DNA transcription machinery.
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Affiliation(s)
- HongZhi Sun
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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36
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Tu X, Batta P, Innocent N, Prisco M, Casaburi I, Belletti B, Baserga R. Nuclear translocation of insulin receptor substrate-1 by oncogenes and Igf-I. Effect on ribosomal RNA synthesis. J Biol Chem 2002; 277:44357-65. [PMID: 12202493 DOI: 10.1074/jbc.m208001200] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The insulin receptor substrate-1 (IRS-1) is one of the major substrates of both the insulin and IGF-I receptors and is generally localized in the cytosol/membrane fraction of the cell. We show here that a substantial fraction of IRS-1 is translocated to the nucleus in mouse embryo fibroblasts (MEF) expressing the simian virus 40 T antigen. Nuclear translocation of IRS-1 occurs also in MEF stimulated with IGF-I or in MEF expressing the oncogene v-src. Nuclear translocation of IRS-1 can be demonstrated by confocal microscopy, immunohistochemistry, or subcellular fractionation. An antibody to IRS-1 immunoprecipitates from nuclear fractions (but not from cytosolic fractions) the upstream binding factor, which is a key regulator of RNA polymerase I activity and ribosomal RNA (rRNA) synthesis. In agreement with this finding, in 32D murine hemopoietic cells, nuclear translocation of IRS-1 correlates with a markedly increased rRNA synthesis. Our experiments suggest that nuclear IRS-1 may play a specialized role in rRNA synthesis and/or processing.
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Affiliation(s)
- Xiao Tu
- Kimmel Cancer Center, Thomas Jefferson University, 233 South 10th Street, 624 BLSB, Philadelphia, Pennsylvania 19107, USA
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37
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Prisco M, Santini F, Baffa R, Liu M, Drakas R, Wu A, Baserga R. Nuclear translocation of insulin receptor substrate-1 by the simian virus 40 T antigen and the activated type 1 insulin-like growth factor receptor. J Biol Chem 2002; 277:32078-85. [PMID: 12063262 DOI: 10.1074/jbc.m204658200] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
32D cells are a murine hemopoietic cell line that undergoes apoptosis upon withdrawal of interleukin-3 (IL-3) from the medium. 32D cells have low levels of the type 1 insulin-like growth factor (IGF-I) receptor and do not express insulin receptor substrate-1 (IRS-1) or IRS-2. Ectopic expression of IRS-1 delays apoptosis but cannot rescue 32D cells from IL-3 dependence. In 32D/IRS-1 cells, IRS-1 is detectable, as expected, in the cytosol/membrane compartment. The SV40 large T antigen is a nuclear protein that, by itself, also fails to protect 32D cells from apoptosis. Co-expression of IRS-1 with the SV40 T antigen in 32D cells results in nuclear translocation of IRS-1 and survival after IL-3 withdrawal. Expression of a human IGF-I receptor in 32D/IRS-1 cells also results in nuclear translocation of IRS-1 and IL-3 independence. The phosphotyrosine-binding domain, but not the pleckstrin domain, is necessary for IRS-1 nuclear translocation. Nuclear translocation of IRS-1 was confirmed in mouse embryo fibroblasts. These results suggest possible new roles for nuclear IRS-1 in IGF-I-mediated growth and anti-apoptotic signaling.
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Affiliation(s)
- Marco Prisco
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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38
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Morrison KB, Tognon CE, Garnett MJ, Deal C, Sorensen PHB. ETV6-NTRK3 transformation requires insulin-like growth factor 1 receptor signaling and is associated with constitutive IRS-1 tyrosine phosphorylation. Oncogene 2002; 21:5684-95. [PMID: 12173038 DOI: 10.1038/sj.onc.1205669] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2002] [Revised: 05/09/2002] [Accepted: 05/14/2002] [Indexed: 12/22/2022]
Abstract
Congenital fibrosarcoma (CFS) and cellular mesoblastic nephroma (CMN) are pediatric spindle cell malignancies that share two specific cytogenetic abnormalities: trisomy of chromosome 11 and a t(12;15)(p13;q25) translocation. The t(12;15) rearrangement creates a transcriptionally active fusion gene that encodes a chimeric oncoprotein, ETV6-NTRK3 (EN). EN transforms NIH3T3 fibroblasts through constitutive activation of both the Ras-mitogen-activated protein kinase (MAPK) pathway and the phosphatidylinositol-3'kinase (PI3K)-Akt pathway. However, the role of trisomy 11 in CFS and CMN remains unknown. In this study we demonstrate elevated expression of the chromosome 11p15.5 insulin-like growth factor 2 gene (IGF2) in CFS and CMN tumors. Moreover, we present evidence that an intact IGF signaling axis is essential for in vitro EN-mediated transformation. EN only very weakly transformed so-called R-murine fibroblasts derived from mice with a targeted disruption of the IGF1 receptor gene (IGFRI), but transformation activity was fully restored in R- cells engineered to re-express IGFRI (R+ cells). We also observed that the major IGFRI substrate, insulin-receptor substrate-1 (IRS-1), was constitutively tyrosine phosphorylated and could be co-immunoprecipitated with EN in either R- or R+ cells expressing the EN oncoprotein. IRS-1 association with Grb2 and PI3K p85, which link IGFRI to the Ras-MAPK and PI3K-Akt pathways, respectively, was enhanced in both cell types in the presence of EN. However, activation of the Ras-MAPK and PI3K-Akt pathways was markedly attenuated in EN-expressing R- cells compared to EN-transformed R+ cells. This suggests that IRS-1 may be functioning as an adaptor in EN signal transduction, but that a link to EN transformation pathways requires the presence of IGFRI. Our findings indicate that an intact IGF signaling axis is essential for EN transformation, and are consistent with a role for trisomy 11 in augmenting this pathway in EN expressing tumors.
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Affiliation(s)
- Kevin B Morrison
- Department of Pathology, BC Research Institute for Children's and Women's Health, and the University of British Columbia, Vancouver, BC V5Z 4H4, Canada
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39
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Lassak A, Del Valle L, Peruzzi F, Wang JY, Enam S, Croul S, Khalili K, Reiss K. Insulin receptor substrate 1 translocation to the nucleus by the human JC virus T-antigen. J Biol Chem 2002; 277:17231-8. [PMID: 11877394 DOI: 10.1074/jbc.m110885200] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin receptor substrate 1 (IRS-1) is the major signaling molecule for the insulin and insulin-like growth factor I receptors, which transduces both metabolic and growth-promoting signals, and has transforming properties when overexpressed in the cells. Here we show that IRS-1 is translocated to the nucleus in the presence of the early viral protein-T-antigen of the human polyomavirus JC. Nuclear IRS-1 was detected in T-antigen-positive cell lines and in T-antigen-positive biopsies from patients diagnosed with medulloblastoma. The IRS-1 domain responsible for a direct JC virus T-antigen binding was localized within the N-terminal portion of IRS-1 molecule, and the binding was independent from IRS-1 tyrosine phosphorylation and was strongly inhibited by IRS-1 serine phosphorylation. In addition, competition for the IRS-1-T-antigen binding by a dominant negative mutant of IRS-1 inhibited growth and survival of JC virus T-antigen-transformed cells in anchorage-independent culture conditions. Based on these findings, we propose a novel role for the IRS-1-T-antigen complex in controlling cellular equilibrium during viral infection. It may involve uncoupling of IRS-1 from its surface receptor and translocation of its function to the nucleus.
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Affiliation(s)
- Adam Lassak
- Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, USA
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40
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Lopez T, Hanahan D. Elevated levels of IGF-1 receptor convey invasive and metastatic capability in a mouse model of pancreatic islet tumorigenesis. Cancer Cell 2002; 1:339-53. [PMID: 12086849 DOI: 10.1016/s1535-6108(02)00055-7] [Citation(s) in RCA: 220] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In a prototypical model of multistage tumorigenesis involving pancreatic islets in RIP1-Tag2 transgenic mice, activation of insulin-like growth factor II (IGF-II) was previously shown to serve as a survival factor that inhibited apoptosis. Now IGF-1R, the receptor tyrosine kinase for IGF-II, has been found to be variably upregulated, first uniformly in dysplastic and angiogenic progenitors and then focally at the margins and in invasive regions of carcinomas. When the levels of IGF-1R were forcibly elevated throughout islet tumorigenesis, progression was accelerated at all stages in the pathway, although apoptosis was not differentially suppressed. Notably, encapsulated tumors were absent; instead, invasive carcinomas with downregulated E-cadherin were prevalent, and the majority of mice had local lymph node metastasis.
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Affiliation(s)
- Theresa Lopez
- Department of Biochemistry & Biophysics and the UCSF Diabetes and Comprehensive Cancer Centers, University of California, San Francisco, 94143, USA
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41
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Buckley DA, Cheng A, Kiely PA, Tremblay ML, O'Connor R. Regulation of insulin-like growth factor type I (IGF-I) receptor kinase activity by protein tyrosine phosphatase 1B (PTP-1B) and enhanced IGF-I-mediated suppression of apoptosis and motility in PTP-1B-deficient fibroblasts. Mol Cell Biol 2002; 22:1998-2010. [PMID: 11884589 PMCID: PMC133665 DOI: 10.1128/mcb.22.7.1998-2010.2002] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The insulin-like growth factor type I (IGF-I) receptor (IGF-IR), activated by its ligands IGF-I and IGF-II, can initiate several signal transduction pathways that mediate suppression of apoptosis, proliferation, differentiation, and transformation. Here we investigated the regulation of IGF-IR activation and function by protein tyrosine phosphatase 1B (PTP-1B). Coexpression of PTP-1B with a beta-chain construct of the IGF-IR (betaWT) inhibited IGF-IR kinase activity in fission yeast Schizosaccharomyces pombe, in COS cells, and in IGF-IR-deficient fibroblasts. In both spontaneously immortalized and simian virus 40 T antigen-transformed embryonic fibroblast cell lines derived from PTP-1B knockout mice, IGF-I induced higher levels of IGF-IR autophosphorylation and kinase activity than were induced in PTP-1B-expressing control cells. PTP-1B-deficient cells exhibited enhanced IGF-I-mediated protection from apoptosis in response to serum withdrawal or etoposide killing, as well as enhanced plating efficiency and IGF-I-mediated motility. Reexpression of PTP-1B in spontaneously immortalized fibroblasts resulted in decreased IGF-IR and AKT activation, as well as decreased protection from apoptosis and decreased motility. These findings demonstrate that PTP-1B can regulate IGF-IR kinase activity and function and that loss of PTP-1B can enhance IGF-I-mediated cell survival, growth, and motility in transformed cells.
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Affiliation(s)
- Deirdre A Buckley
- Cell Biology Laboratory, Department of Biochemistry and Bioscience Research Institute, National University of Ireland, Cork, Ireland
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42
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Emkey R, Kahn CR. Molecular Aspects of Insulin Signaling. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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43
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Wang JY, Del Valle L, Gordon J, Rubini M, Romano G, Croul S, Peruzzi F, Khalili K, Reiss K. Activation of the IGF-IR system contributes to malignant growth of human and mouse medulloblastomas. Oncogene 2001; 20:3857-68. [PMID: 11439349 DOI: 10.1038/sj.onc.1204532] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2000] [Revised: 04/03/2001] [Accepted: 04/09/2001] [Indexed: 11/09/2022]
Abstract
Insulin-like growth factor I receptor (IGF-IR) has been implicated in the normal and malignant growth of many cell types including cells from the central nervous system. In the cerebellar cortex IGF-IR mRNA is found in granular cells and IGF-I stimulation is mitogenic and protects cells from low-potassium-induced apoptosis. Since primitive neuroectodermal tumors/medulloblastomas (PNETs/medulloblastomas) are suspected to originate from the external cerebellar granular layer, it is reasonable to postulate that IGF-IR and/or its signaling molecules may contribute to the transformation of these poorly differentiated cells. To study activation of the IGF-IR system in medulloblastomas, we have utilized an antibody (anti-pY1316) that specifically recognizes the phosphorylated (active) form of the IGF-IR. Medulloblastoma biopsy specimens were positive when examined immunohistochemically with anti-Y1316 antibody. Further analysis of the IGF-IR system was performed in three human (Daoy, TE-671, D283 Med) and four mouse (BsB8, BsB13, Bs-1b, Bs-1c) medulloblastoma cell lines. All the murine cell lines examined express IGF-IR and PI3-kinase at relatively normal levels, and grossly overexpress IRS-1, when compared with normal mouse cerebellum. Within 15 min following IGF-I stimulation both mouse and human cell lines phosphorylate the beta subunit of the IGF-IR, IRS-1, Akt, and MAP kinases. They respond with cell proliferation when stimulated solely with IGF-I and are strongly inhibited when challenged with a dominant negative mutant of the IGF-IR (486/STOP), or with antisense oligonucleotides against the IGF-IR mRNA.
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Affiliation(s)
- J Y Wang
- Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, 1900 North 12th Street, Biology Life Science Building, Room 238 Philadelphia, Pennsylvania, PA 19122, USA
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44
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Tu Y, Liang L, Frank SJ, Wu C. Src homology 3 domain-dependent interaction of Nck-2 with insulin receptor substrate-1. Biochem J 2001; 354:315-22. [PMID: 11171109 PMCID: PMC1221658 DOI: 10.1042/0264-6021:3540315] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Insulin receptor substrate-1 (IRS-1) is a multi-domain protein that mediates signal transduction from receptors for insulin and other growth factors to a variety of downstream molecules through both tyrosine-phosphorylation-dependent and -independent interactions. While the tyrosine-phosphorylation-dependent interactions mediated by IRS-1 have been well characterized, the molecular basis underlying the tyrosine-phosphorylation-independent IRS-1 interactions is largely unknown. We previously detected, in an in vitro binding assay, interactions of Nck-2 Src homology (SH) 3 domains with IRS-1. We show here that IRS-1 associates with Nck-2 in vivo. Additionally, we have investigated the molecular basis underlying the IRS-1-Nck-2 complex formation. We have found that (i) mutations at the highly conserved tryptophan within the Nck-2 SH3 domains markedly reduced the association with IRS-1, (ii) interactions mediated by multiple SH3 domains enhance the complex formation of Nck-2 with IRS-1, (iii) deletion of either the phosphotyrosine-binding/Shc and IRS-1 NPXY-binding (PTB/SAIN) domains or the Pre-C-terminal domain of IRS-1, but not the pleckstrin homology (PH) domain, reduced the Nck-2 binding, (iv) PTB/SAIN domains or the Pre-C-terminal domain alone is capable of interacting with Nck-2, and (v) the IRS-1-Nck-2 interaction occurs in the absence of other proteins and therefore is direct. These results establish that IRS-1 is a bona fide target of the Nck-2 SH3 domains and reveal that IRS-1 forms a complex with Nck-2 via direct interactions mediated by multiple domains from both binding partners.
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Affiliation(s)
- Y Tu
- Department of Pathology, University of Pittsburgh, 3550 Terrace Street, Pittsburgh, PA 15261, U.S.A
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45
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Gottifredi V, Pelicci G, Munarriz E, Maione R, Pelicci PG, Amati P. Polyomavirus large T antigen induces alterations in cytoplasmic signalling pathways involving Shc activation. J Virol 1999; 73:1427-37. [PMID: 9882348 PMCID: PMC103967 DOI: 10.1128/jvi.73.2.1427-1437.1999] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It has been extensively demonstrated that growth factors play a key role in the regulation of proliferation. Several lines of evidence support the hypothesis that for the induction of cell cycle progression in the absence of exogenous growth factors, oncogenes must either induce autocrine growth factor secretion or, alternatively, activate their receptors or their receptor substrates. Cells expressing polyomavirus large T antigen (PyLT) display reduced growth factor requirements, but the mechanisms underlying this phenomenon have yet to be explored. We conducted tests to see whether the reduction in growth factor requirements induced by PyLT was related to alterations of growth factor-dependent signals. To this end, we analyzed the phosphorylation status of a universal tyrosine kinase substrate, the transforming Shc adapter protein, in fibroblasts expressing the viral oncogene. We report that the level of Shc phosphorylation does not decrease in PyLT-expressing fibroblasts after growth factor withdrawal and that this PyLT-mediated effect does not require interaction with protein encoded by the retinoblastoma susceptibility gene. We also found that the chronic activation of the adapter protein is correlated with the binding of Shc to Grb-2 and with defects in the downregulation of mitogen-activated protein kinases. In fibroblasts expressing the nuclear oncoprotein, we also observed the formation of a PyLT-Shc complex that might be involved in constitutive phosphorylation of the adapter protein. Viewed comprehensively, these results suggest that the cell cycle progression induced by PyLT may depend not only on the direct inactivation of nuclear antioncogene products but also on the indirect induction, through the alteration of cytoplasmic pathways, of growth factor-dependent nuclear signals.
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Affiliation(s)
- V Gottifredi
- Sezione di Genetica Molecolare, Dipartimento di Biotecnologie Cellulari ed Ematologia, Istituto Pasteur-Fondazione Cenci Bolognetti, Università di Roma La Sapienza, 00161 Rome, Italy.
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46
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Abstract
New molecules discovered during the past ten years have created a rational framework to understand signalling transduction by a broad range of growth factors and cytokines, including insulin. Insulin action is initiated through the insulin receptor, a transmembrane glycoprotein with intrinsic protein tyrosine kinase activity. The tyrosine kinase mediates the insulin response through tyrosine phosphorylation of various cellular substrates, in particular the IRS-proteins. During insulin-stimulated tyrosine phosphorylation, the IRS-proteins mediate a broad biological response by binding and activating various enzymes or adapter molecules. Although we are far from a complete understanding of the insulin signalling system and its failure, enough pieces of the puzzle are falling into place that mechanism-based solutions to insulin resistance encountered with type II diabetes may soon be attainable.
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Affiliation(s)
- M F White
- Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
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47
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White MF. The IRS-signalling system: a network of docking proteins that mediate insulin action. Mol Cell Biochem 1999. [PMID: 9609109 DOI: 10.1023/a:1006806722619] [Citation(s) in RCA: 468] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
New molecules discovered during the past ten years have created a rational framework to understand signalling transduction by a broad range of growth factors and cytokines, including insulin. Insulin action is initiated through the insulin receptor, a transmembrane glycoprotein with intrinsic protein tyrosine kinase activity. The tyrosine kinase mediates the insulin response through tyrosine phosphorylation of various cellular substrates, in particular the IRS-proteins. During insulin-stimulated tyrosine phosphorylation, the IRS-proteins mediate a broad biological response by binding and activating various enzymes or adapter molecules. Although we are far from a complete understanding of the insulin signalling system and its failure, enough pieces of the puzzle are falling into place that mechanism-based solutions to insulin resistance encountered with type II diabetes may soon be attainable.
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Affiliation(s)
- M F White
- Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
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48
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White MF. The IRS-signalling system: a network of docking proteins that mediate insulin action. Mol Cell Biochem 1998; 182:3-11. [PMID: 9609109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
New molecules discovered during the past ten years have created a rational framework to understand signalling transduction by a broad range of growth factors and cytokines, including insulin. Insulin action is initiated through the insulin receptor, a transmembrane glycoprotein with intrinsic protein tyrosine kinase activity. The tyrosine kinase mediates the insulin response through tyrosine phosphorylation of various cellular substrates, in particular the IRS-proteins. During insulin-stimulated tyrosine phosphorylation, the IRS-proteins mediate a broad biological response by binding and activating various enzymes or adapter molecules. Although we are far from a complete understanding of the insulin signalling system and its failure, enough pieces of the puzzle are falling into place that mechanism-based solutions to insulin resistance encountered with type II diabetes may soon be attainable.
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Affiliation(s)
- M F White
- Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
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49
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Ogawa W, Matozaki T, Kasuga M. Role of binding proteins to IRS-1 in insulin signalling. Mol Cell Biochem 1998; 182:13-22. [PMID: 9609110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Insulin elicits its divergent metabolic and mitogenic effects by binding to its specific receptor, which belongs to the family of receptor tyrosine kinases. The activated insulin receptor phosphorylates the intracellular substrate IRS-1, which then binds various signalling molecules that contain SRC homology 2 domains, thereby propagating the insulin signal. Among these IRS-1-binding proteins, the Grb2-Sos complex and the protein tyrosine phosphatase SHP-2 transmit mitogenic signals through the activation of Ras, and phosphoinositide 3-kinase is implicated in the major metabolic actions of insulin. Although substantial evidence indicates the importance of IRS-1 in insulin signal transduction, the generation of IRS-1-deficient mice has revealed the existence of redundant signalling pathways.
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Affiliation(s)
- W Ogawa
- Second Department of Internal Medicine, Kobe University School of Medicine, Japan
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50
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White MF, Yenush L. The IRS-signaling system: a network of docking proteins that mediate insulin and cytokine action. Curr Top Microbiol Immunol 1997; 228:179-208. [PMID: 9401207 DOI: 10.1007/978-3-642-80481-6_8] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- M F White
- Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
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