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Salati NA, Sharma M, Rao NN, Shetty SS, Radhakrishnan RA. Role of osteopontin in oral epithelial dysplasia, oral submucous fibrosis and oral squamous cell carcinoma. J Oral Maxillofac Pathol 2023; 27:706-714. [PMID: 38304518 PMCID: PMC10829450 DOI: 10.4103/jomfp.jomfp_492_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/27/2022] [Accepted: 03/06/2023] [Indexed: 02/03/2024] Open
Abstract
Background Inflammatory cells and cytokines in the chronically injured mucosa promote fibrosis in the oral submucous fibrosis (OSF) fibrotic milieu. Osteopontin (OPN) is a wound-healing mediator that upregulates the inflammatory response and is involved in the malignancy and fibrosis of multiple organ systems. Objectives We investigated the expression of OPN in oral potentially malignant disorders (OPMDs) and oral squamous cell carcinomas (OSCCs) to determine its role in the malignant transformation and fibrosis of oral tissues. The expression of OPN in OPMDs and OSCCs was compared and correlated, and the role of OPN as a fibrotic mediator in OSF was explained. Study Design A total of 30 cases of normal mucosa and OPMDs (mild dysplasia, severe dysplasia, OSF and OSCCs) were studied by purposive sampling. In these groups, OPN immunoreactivity was examined and correlated with clinical findings. Results In mild dysplasia, OPN expression was restricted to the basal cell layer with moderate staining intensity. In severe dysplasia, it was extremely intense and extended throughout the epithelium. In the OSF, OPN expression was moderate in the perinuclear areas of the basal cell layer. The expression of OPN was very strong in OSCC. A flow diagram explaining the profibrotic role of OPN in OSF has been provided. Conclusion A positive role of OPN in both pathogenesis and malignant transformation of OPMDs and OSCC has been demonstrated.
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Affiliation(s)
- Nasir A. Salati
- Department of Oral and Maxillofacial Pathology, Dr. Ziauddin Ahmad Dental College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Mohit Sharma
- Department of Oral Pathology, SGT Dental College Hospital and Research Institute, Gurugram, Haryana, India
| | - Nirmala N. Rao
- Former Dean, Manipal College of Dental Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Smitha S. Shetty
- Department of Oral Pathology, Manipal College of Dental Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Raghu A. Radhakrishnan
- Department of Oral Pathology, Manipal College of Dental Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
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The Roles of Osteopontin in the Pathogenesis of West Nile Encephalitis. Vaccines (Basel) 2020; 8:vaccines8040748. [PMID: 33317005 PMCID: PMC7768535 DOI: 10.3390/vaccines8040748] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/03/2020] [Accepted: 12/06/2020] [Indexed: 12/18/2022] Open
Abstract
Osteopontin (OPN), a multifunctional protein encoded by the secreted phosphoprotein-1 (Spp-1) gene in humans, plays important roles in a variety of physiological conditions, such as biomineralization, bone remodeling and immune functions. OPN also has significant roles in the pathogenesis of autoimmune, allergy and inflammatory diseases, as well as bacterial, fungal and viral infections. West Nile virus (WNV), a mosquito-transmitted flavivirus, is the leading agent for viral encephalitis in North America. Recent progress has been made in understanding both the biological functions of OPN and the pathogenesis of WNV. In this review article, we have summarized the current understanding of the biology of OPN and its vital roles in the pathogenesis of WNV encephalitis.
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Biological role of site-specific O-glycosylation in cell adhesion activity and phosphorylation of osteopontin. Biochem J 2018; 475:1583-1595. [PMID: 29626154 DOI: 10.1042/bcj20170205] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 02/08/2018] [Accepted: 04/03/2018] [Indexed: 01/13/2023]
Abstract
Osteopontin (OPN) is an extracellular glycosylated phosphoprotein that promotes cell adhesion by interacting with several integrin receptors. We previously reported that an OPN mutant lacking five O-glycosylation sites (Thr134/Thr138/Thr143/Thr147/Thr152) in the threonine/proline-rich region increased cell adhesion activity and phosphorylation compared with the wild type. However, the role of O-glycosylation in cell adhesion activity and phosphorylation of OPN remains to be clarified. Here, we show that site-specific O-glycosylation in the threonine/proline-rich region of OPN affects its cell adhesion activity and phosphorylation independently and/or synergistically. Using site-directed mutagenesis, we found that OPN mutants with substitution sets of Thr134/Thr138 or Thr143/Thr147/Thr152 had decreased and increased cell adhesion activity, respectively. In contrast, the introduction of a single mutation into the O-glycosylation sites had no effect on OPN cell adhesion activity. An adhesion assay using function-blocking antibodies against αvβ3 and β1 integrins, as well as αvβ3 integrin-overexpressing A549 cells, revealed that site-specific O-glycosylation affected the association of OPN with the two integrins. Phosphorylation analyses using phos-tag and LC-MS/MS indicated that phosphorylation levels and sites were influenced by the O-glycosylation status, although the number of O-glycosylation sites was not correlated with the phosphorylation level in OPN. Furthermore, a correlation analysis between phosphorylation level and cell adhesion activity in OPN mutants with the site-specific O-glycosylation showed that they were not always correlated. These results provide conclusive evidence of a novel regulatory mechanism of cell adhesion activity and phosphorylation of OPN by site-specific O-glycosylation.
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4
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Clemente N, Raineri D, Cappellano G, Boggio E, Favero F, Soluri MF, Dianzani C, Comi C, Dianzani U, Chiocchetti A. Osteopontin Bridging Innate and Adaptive Immunity in Autoimmune Diseases. J Immunol Res 2016; 2016:7675437. [PMID: 28097158 PMCID: PMC5206443 DOI: 10.1155/2016/7675437] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Revised: 10/02/2016] [Accepted: 10/19/2016] [Indexed: 12/21/2022] Open
Abstract
Osteopontin (OPN) regulates the immune response at multiple levels. Physiologically, it regulates the host response to infections by driving T helper (Th) polarization and acting on both innate and adaptive immunity; pathologically, it contributes to the development of immune-mediated and inflammatory diseases. In some cases, the mechanisms of these effects have been described, but many aspects of the OPN function remain elusive. This is in part ascribable to the fact that OPN is a complex molecule with several posttranslational modifications and it may act as either an immobilized protein of the extracellular matrix or a soluble cytokine or an intracytoplasmic molecule by binding to a wide variety of molecules including crystals of calcium phosphate, several cell surface receptors, and intracytoplasmic molecules. This review describes the OPN structure, isoforms, and functions and its role in regulating the crosstalk between innate and adaptive immunity in autoimmune diseases.
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Affiliation(s)
- Nausicaa Clemente
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), “A. Avogadro” University of Piemonte Orientale (UPO), Novara, Italy
| | - Davide Raineri
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), “A. Avogadro” University of Piemonte Orientale (UPO), Novara, Italy
| | - Giuseppe Cappellano
- Biocenter, Division for Experimental Pathophysiology and Immunology, Laboratory of Autoimmunity, Medical University of Innsbruck, Innsbruck, Austria
| | - Elena Boggio
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), “A. Avogadro” University of Piemonte Orientale (UPO), Novara, Italy
| | - Francesco Favero
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), “A. Avogadro” University of Piemonte Orientale (UPO), Novara, Italy
| | - Maria Felicia Soluri
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), “A. Avogadro” University of Piemonte Orientale (UPO), Novara, Italy
| | - Chiara Dianzani
- Department of Drug Science and Technology, University of Torino, Torino, Italy
| | - Cristoforo Comi
- Department of Translational Medicine, Neurology Unit, “A. Avogadro” UPO, Novara, Italy
| | - Umberto Dianzani
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), “A. Avogadro” University of Piemonte Orientale (UPO), Novara, Italy
| | - Annalisa Chiocchetti
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), “A. Avogadro” University of Piemonte Orientale (UPO), Novara, Italy
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5
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Lin J, Myers AL, Wang Z, Nancarrow DJ, Ferrer-Torres D, Handlogten A, Leverenz K, Bao J, Thomas DG, Wang TD, Orringer MB, Reddy RM, Chang AC, Beer DG, Lin L. Osteopontin (OPN/SPP1) isoforms collectively enhance tumor cell invasion and dissemination in esophageal adenocarcinoma. Oncotarget 2016; 6:22239-57. [PMID: 26068949 PMCID: PMC4673160 DOI: 10.18632/oncotarget.4161] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/14/2015] [Indexed: 01/26/2023] Open
Abstract
Esophageal adenocarcinoma (EAC) is often diagnosed at an advanced stage, thus understanding the molecular basis for EAC invasion and metastasis is critical. Here we report that SPP1/OPN was highly overexpressed in primary EACs and intracellularly localized to tumor cells. We further demonstrate that all known OPN isoforms (OPNa, b, c, 4 and 5) were frequently co-overexpressed in primary EACs. Distinct pro-invasion and dissemination phenotypes of isoform-specific OPNb and OPNc stable transfectants were observed. Expression of OPNb significantly enhanced cell migration and adhesion to laminin. In contrast, OPNc cells showed significantly decreased cell migration yet increased cell detachment. Enhanced invasion, both in vitro and in vivo, was observed for OPNb- but not OPNc-expressing cells. Inhibition of RGD integrins, one family of OPN receptors, attenuated OPNb cell migration, abrogated OPNb cell adhesion and significantly reduced OPNb cell clonogenic survival but did not affect OPNc phenotypes, indicating that OPNb but not OPNc acts through integrin-dependent signaling. Differential expression of vimentin, E-cadherin and β-catenin in OPN stable cells may account for the variation in cell adhesion and detachment between these isoforms. We conclude that while all OPN isoforms are frequently co-overexpressed in primary EACs, isoforms OPNb and OPNc enhance invasion and dissemination through collective yet distinct mechanisms.
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Affiliation(s)
- Jules Lin
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Amy L Myers
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Zhuwen Wang
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Derek J Nancarrow
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Daysha Ferrer-Torres
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Amy Handlogten
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Kimmy Leverenz
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Julia Bao
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Dafydd G Thomas
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Thomas D Wang
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Mark B Orringer
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Rishindra M Reddy
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Andrew C Chang
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - David G Beer
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Lin Lin
- Section of Thoracic Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
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Osteopontin O-glycosylation contributes to its phosphorylation and cell-adhesion properties. Biochem J 2014; 463:93-102. [PMID: 25000122 DOI: 10.1042/bj20140060] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OPN (osteopontin) is a multiphosphorylated extracellular glycoprotein, which has important roles in bone remodelling, inflammation and cancer metastasis. OPN regulates cell spreading and adhesion primarily through its association with several integrins such as αvβ3, and its phosphorylation affects these processes. However, the mechanism by which OPN O-glycosylation affects these processes is not completely understood. In the present study, we demonstrated that OPN O-glycosylation self-regulates its biological activities and also affects its phosphorylation status. We prepared two recombinant OPNs, WT (wild-type)-OPN and mutant OPN (ΔO-OPN), which lacks five O-glycosylation sites at a threonine/proline-rich region. O-glycan defects in OPN increased its phosphorylation level, as observed by dephosphorylation assays. Moreover, compared with WT-OPN, ΔO-OPN exhibited enhanced cell spreading and adhesion activities and decreased associations with β1 integrins. This suggested that defects in O-glycans in OPN altered these activities, and that β1 integrins have a less important role in adhesion to ΔO-OPN. The cell-adhesion activity of dephosphorylated ΔO-OPN was higher than the cell-adhesion activities of ΔO-OPN and dephosphorylated WT-OPN. This suggested that some of the phosphorylation in ΔO-OPN caused by O-glycan defects and O-glycans of OPN suppressed the OPN cell-adhesion activity. Thus functional activities of OPN can be determined by the combined glycosylation and phosphorylation statuses and not by either status alone.
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7
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Li H, Shen H, Yan G, Zhang Y, Liu M, Fang P, Yu H, Yang P. Site-specific structural characterization of O-glycosylation and identification of phosphorylation sites of recombinant osteopontin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1854:581-91. [PMID: 25450502 DOI: 10.1016/j.bbapap.2014.09.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 08/25/2014] [Accepted: 09/30/2014] [Indexed: 12/21/2022]
Abstract
Osteopontin (OPN) plays a key role in multiple physiological and pathological processes such as cytokine production, mineralization, inflammation, immune responses, and tumorigenesis. Post-translational modifications (PTMs) of OPN significantly affect its structure and biological properties; however, site-specific characterization of O-glycosylation in human OPN has not been reported. In this work, we profiled the overall glycan pattern of human recombinant OPN using a lectin array and completed detailed structural analysis of O-glycopeptides by mass spectrometry (MS). We detected 28 O-glycopeptides from 7 O-glycosylation regions of human OPN, occupied by highly heterogeneous O-glycans. These O-glycans carried, in part, functionally relevant epitopes such as T antigens (Galβ1-3GalNAcα1-), sialyl-Tn antigens, sialyl-T antigens, and sialyl-Le(x/a) antigens [Neuα2-3Galβ1-4(Fucα1-3)GlcNAc/Neuα2-3Galβ1-3(Fucα1-4)GlcNAc]. MS(3) spectra of the generated O-glycopeptides showed cleavages of the peptide backbone and provided essential information on the peptide sequence. Furthermore, 26 phosphorylation sites were identified by reverse-phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS), including a novel one (Y209). We provide a detailed, site-specific structural characterization of O-glycosylation and identify the phosphorylation sites of OPN. These data lay the foundation for further research into the role of oligosaccharides and phosphorylation of recombinant human OPN. This article is part of a Special Issue entitled: Medical Proteomics.
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Affiliation(s)
- Hong Li
- Department of Chemistry, Fudan University, Shanghai 200032, PR China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PR China
| | - Huali Shen
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PR China
| | - Guoquan Yan
- Department of Chemistry, Fudan University, Shanghai 200032, PR China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PR China
| | - Yang Zhang
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PR China
| | - Mingqi Liu
- Department of Chemistry, Fudan University, Shanghai 200032, PR China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PR China
| | - Pan Fang
- Department of Chemistry, Fudan University, Shanghai 200032, PR China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PR China
| | - Hongxiu Yu
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PR China.
| | - Pengyuan Yang
- Department of Chemistry, Fudan University, Shanghai 200032, PR China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PR China.
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Long P, Samnakay P, Jenner P, Rose S. A yeast two-hybrid screen reveals that osteopontin associates with MAP1A and MAP1B in addition to other proteins linked to microtubule stability, apoptosis and protein degradation in the human brain. Eur J Neurosci 2012; 36:2733-42. [DOI: 10.1111/j.1460-9568.2012.08189.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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9
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Shojaei F, Scott N, Kang X, Lappin PB, Fitzgerald AA, Karlicek S, Simmons BH, Wu A, Lee JH, Bergqvist S, Kraynov E. Osteopontin induces growth of metastatic tumors in a preclinical model of non-small lung cancer. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2012; 31:26. [PMID: 22444159 PMCID: PMC3325875 DOI: 10.1186/1756-9966-31-26] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 03/23/2012] [Indexed: 12/18/2022]
Abstract
Osteopontin (OPN), also known as SPP1 (secreted phosphoprotein), is an integrin binding glyco-phosphoprotein produced by a variety of tissues. In cancer patients expression of OPN has been associated with poor prognosis in several tumor types including breast, lung, and colorectal cancers. Despite wide expression in tumor cells and stroma, there is limited evidence supporting role of OPN in tumor progression and metastasis. Using phage display technology we identified a high affinity anti-OPN monoclonal antibody (hereafter AOM1). The binding site for AOM1 was identified as SVVYGLRSKS sequence which is immediately adjacent to the RGD motif and also spans the thrombin cleavage site of the human OPN. AOM1 efficiently inhibited OPNa binding to recombinant integrin αvβ3 with an IC50 of 65 nM. Due to its unique binding site, AOM1 is capable of inhibiting OPN cleavage by thrombin which has been shown to produce an OPN fragment that is biologically more active than the full length OPN. Screening of human cell lines identified tumor cells with increased expression of OPN receptors (αvβ3 and CD44v6) such as mesothelioma, hepatocellular carcinoma, breast, and non-small cell lung adenocarcinoma (NSCLC). CD44v6 and αvβ3 were also found to be highly enriched in the monocyte, but not lymphocyte, subset of human peripheral blood mononuclear cells (hPBMCs). In vitro, OPNa induced migration of both tumor and hPBMCs in a transwell migration assay. AOM1 significantly blocked cell migration further validating its specificity for the ligand. OPN was found to be enriched in mouse plasma in a number of pre-clinical tumor model of non-small cell lung cancers. To assess the role of OPN in tumor growth and metastasis and to evaluate a potential therapeutic indication for AOM1, we employed a KrasG12D-LSLp53fl/fl subcutaneously implanted in vivo model of NSCLC which possesses a high capacity to metastasize into the lung. Our data indicated that treatment of tumor bearing mice with AOM1 as a single agent or in combination with Carboplatin significantly inhibited growth of large metastatic tumors in the lung further supporting a role for OPN in tumor metastasis and progression.
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Affiliation(s)
- Farbod Shojaei
- Pfizer Global Research and Development, Department of Oncology, La Jolla, CA, USA.
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Thurgood LA, Sørensen ES, Ryall RL. The effect of intracrystalline and surface-bound osteopontin on the degradation and dissolution of calcium oxalate dihydrate crystals in MDCKII cells. ACTA ACUST UNITED AC 2011; 40:1-15. [PMID: 21932131 DOI: 10.1007/s00240-011-0423-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 08/22/2011] [Indexed: 01/12/2023]
Abstract
In vivo, urinary crystals are associated with proteins located within the mineral bulk as well as upon their surfaces. Proteins incarcerated within the mineral phase of retained crystals could act as a defence against urolithiasis by rendering them more vulnerable to destruction by intracellular and interstitial proteases. The aim of this study was to examine the effects of intracrystalline and surface-bound osteopontin (OPN) on the degradation and dissolution of urinary calcium oxalate dihydrate (COD) crystals in cultured Madin Darby canine kidney (MDCK) cells. [(14)C]-oxalate-labelled COD crystals with intracrystalline (IC), surface-bound (SB) and IC + SB OPN, were generated from ultrafiltered (UF) urine containing 0, 1 and 5 mg/L human milk OPN and incubated with MDCKII cells, using UF urine as the binding medium. Crystal size and degradation were assessed using field emission scanning electron microscopy (FESEM) and dissolution was quantified by the release of radioactivity into the culture medium. Crystal size decreased directly with OPN concentration. FESEM examination indicated that crystals covered with SB OPN were more resistant to cellular degradation than those containing IC OPN, whose degree of disruption appeared to be related to OPN concentration. Whether bound to the crystal surface or incarcerated within the mineral interior, OPN inhibited crystal dissolution in direct proportion to its concentration. Under physiological conditions OPN may routinely protect against stone formation by inhibiting the growth of COD crystals, which would encourage their excretion in urine and thereby perhaps partly explain why, compared with calcium oxalate monohydrate crystals, COD crystals are more prevalent in urine, but less common in kidney stones.
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Affiliation(s)
- Lauren A Thurgood
- Urology Unit, Department of Surgery, Flinders Medical Centre, Flinders University, Bedford Park, SA 5042, Australia
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11
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Pre- and post-translational regulation of osteopontin in cancer. J Cell Commun Signal 2011; 5:111-22. [PMID: 21516514 DOI: 10.1007/s12079-011-0130-6] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 03/15/2011] [Indexed: 12/15/2022] Open
Abstract
Osteopontin (OPN) is a matricellular protein that binds to a number of cell surface receptors including integrins and CD44. It is expressed in many tissues and secreted into body fluids including blood, milk and urine. OPN plays important physiological roles in bone remodeling, immune response and inflammation. It is also a tumour-associated protein, and elevated OPN levels are associated with tumour formation, progression and metastasis. Research has revealed a promising role for OPN as a cancer biomarker. OPN is subject to alternative splicing, as well as post-translational modifications such as phosphorylation, glycosylation and proteolytic cleavage. Functional differences have been revealed for different isoforms and post-translational modifications. The pattern of isoform expression and post-translational modification is cell-type specific and may influence the potential role of OPN in malignancy and as a cancer biomarker.
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12
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Frenzel DF, Weiss JM. Osteopontin and allergic disease: pathophysiology and implications for diagnostics and therapy. Expert Rev Clin Immunol 2011; 7:93-109. [PMID: 21162653 DOI: 10.1586/eci.10.82] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Osteopontin (OPN) is a phosphoglycoprotein that is expressed by various immune cells in a secreted and intracellular form. It has cytokine, chemotactic and cell signaling functions enhancing Th1 and Th17 immunity and protects against apoptosis. Recent studies found OPN to be modulatory in cell-mediated and immediate-type allergic diseases. In allergic asthma, OPN enhances sensitization but downmodulates Th2-driven IL-4-dominated inflammation. The finding that OPN expression is augmented during specific immunotherapy supports a Th2 suppressive effect of OPN. In Th1-driven delayed-type allergy, such as allergic contact dermatitis, OPN supports dendritic cell migration and IL-12 expression and is secreted by T effector cells and keratinocytes, augmenting Th1-mediated allergy and supporting disease chronification. There are numerous missing links as to how OPN variants modulate allergic inflammation through different OPN receptors. OPN research in allergy is an interesting, rapidly expanding field that has high potential for translational research.
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Affiliation(s)
- Denis F Frenzel
- University of Ulm, Department of Dermatology and Allergy, Maienweg 12, D-89081 Ulm, Germany
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Zhou HY, Salih E, Glimcher MJ. The isolation and characterization of glycosylated phosphoproteins from herring fish bones. J Biol Chem 2010; 285:36170-8. [PMID: 20833721 DOI: 10.1074/jbc.m110.146910] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Past studies of bone extracellular matrix phosphoproteins such as osteopontin and bone sialoprotein have yielded important biological information regarding their role in calcification and the regulation of cellular activity. Most of these studies have been limited to proteins extracted from mammalian and avian vertebrates and nonvertebrates. The present work describes the isolation and purification of two major highly glycosylated and phosphorylated extracellular matrix proteins of 70 and 22 kDa from herring fish bones. The 70-kDa phosphoprotein has some characteristics of osteopontin with respect to amino acid composition and susceptibility to thrombin cleavage. Unlike osteopontin, however, it was found to contain high levels of sialic acid similar to bone sialoprotein. The 22-kDa protein has very different properties such as very high content of phosphoserine (∼270 Ser(P) residues/1000 amino acid residues), Ala, and Asx residues. The N-terminal amino acid sequence analysis of both the 70-kDa (NPIMA(M)ETTS(M)DSKVNPLL) and the 22-kDa (NQDMAMEASSDPEAA) fish phosphoproteins indicate that these unique amino acid sequences are unlike any published in protein databases. An enzyme-linked immunosorbent assay revealed that the 70-kDa phosphoprotein was present principally in bone and in calcified scales, whereas the 22-kDa phosphoprotein was detected only in bone. Immunohistological analysis revealed diffusely positive immunostaining for both the 70- and 22-kDa phosphoproteins throughout the matrix of the bone. Overall, this work adds additional support to the concept that the mechanism of biological calcification has common evolutionary and fundamental bases throughout vertebrate species.
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Affiliation(s)
- Hai-Yan Zhou
- Laboratory for the Study of Skeletal Disorders and Rehabilitation, Department of Orthopedic Surgery, Harvard Medical School and Children's Hospital Boston, Boston, Massachusetts 02115-5737, USA
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Shevde LA, Das S, Clark DW, Samant RS. Osteopontin: an effector and an effect of tumor metastasis. Curr Mol Med 2010; 10:71-81. [PMID: 20205680 DOI: 10.2174/156652410791065381] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2008] [Accepted: 05/11/2008] [Indexed: 12/12/2022]
Abstract
Osteopontin (OPN) is a matricellular protein that is produced by multiple tissues in our body and is most abundant in bone. It is also produced by cancer cells and plays a determinative role in the growth, progression and metastasis of cancer. Clinically, OPN has been reported to be upregulated in tumor cells per se; this is also reflected by increased levels of OPN in the circulation. Thus, increased OPN levels the plasma are an effect of tumor growth and progression. Functionally, high OPN levels are determinative of higher incidence of bone metastases in mouse models and are clinically correlated with metastatic bone disease and bone resorption in advanced breast cancer patients. Several research efforts have been made to therapeutically target and inhibit the activities of OPN. In this article we have reviewed OPN in its role as an effector of critical steps in tumor progression and metastasis, with a particular emphasis on its role in facilitating bone metastasis of breast cancer. We have also addressed the role of the host-derived OPN in influencing the malignant behavior of the tumor cells.
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Affiliation(s)
- L A Shevde
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA.
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15
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Take Y, Nakata K, Hashimoto J, Tsuboi H, Nishimoto N, Ochi T, Yoshikawa H. Specifically modified osteopontin in rheumatoid arthritis fibroblast-like synoviocytes supports interaction with B cells and enhances production of interleukin-6. ACTA ACUST UNITED AC 2009; 60:3591-601. [DOI: 10.1002/art.25020] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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16
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Sialyl-Tn vaccine induces antibody-mediated tumour protection in a relevant murine model. Br J Cancer 2009; 100:1746-54. [PMID: 19436292 PMCID: PMC2695689 DOI: 10.1038/sj.bjc.6605083] [Citation(s) in RCA: 253] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Changes in the composition of glycans added to glycoproteins and glycolipids are characteristic of the change to malignancy. Sialyl-Tn (STn) is expressed by 25-30% of breast carcinomas but its expression on normal tissue is highly restricted. Sialyl-Tn is an O-linked disaccharide that can be carried on various glycoproteins. One such glycoprotein MUC1 is expressed by the vast majority of breast carcinomas. Both STn and MUC1 have been considered as targets for immunotherapy of breast cancer patients. Here we used different immunogens to target STn in an MUC1 transgenic mouse model of tumour challenge. We show that synthetic STn coupled to keyhole limpet haemocyanin (Theratope), induced antibodies to STn that recognised the glycan carried on a number of glycoproteins and in these mice a significant delay in tumour growth was observed. The protection was dependent on STn being expressed by the tumour and was antibody mediated. Affinity chromatography of the STn-expressing tumour cell line, followed by mass spectrometry, identified osteopontin as a novel STn-carrying glycoprotein which was highly expressed by the tumours. These results suggest that if antibodies can be induced to a number of targets expressed by the tumour cells, a humoral response can be effective in controlling tumour growth.
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17
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Kazanecki CC, Uzwiak DJ, Denhardt DT. Control of osteopontin signaling and function by post-translational phosphorylation and protein folding. J Cell Biochem 2008; 102:912-24. [PMID: 17910028 DOI: 10.1002/jcb.21558] [Citation(s) in RCA: 211] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Osteopontin (OPN) plays roles in a variety of cellular processes from bone resorption and extracellular matrix (ECM) remodeling to immune cell activation and inhibition of apoptosis. Because it binds receptors (integrins, CD44 variants) typically engaged by ECM molecules, OPN acts as a "soluble" ECM molecule. A persistent theme throughout the characterization of how OPN functions has been the importance of phosphorylation. The source of the OPN used in specific experiments and the location of modified sites is an increasingly important consideration for OPN research. We review briefly some of the ways OPN impacts on the biology of mammalian systems with an emphasis on the importance of serine phosphorylation in modulating its signaling ability. We describe experiments that support the hypothesis that differences in the post-translational phosphorylation of OPN expressed by different cell types regulate how it impacts on target cells. Analyses of OPN's potential secondary structure reveal a possible beta-sheet conformation that offers an interpretation of certain experimental observations, specifically the effect of thrombin cleavage; it is consistent with an interaction between the C-terminal region of the protein and the central integrin-binding RGD sequence.
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18
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Christensen B, Kazanecki CC, Petersen TE, Rittling SR, Denhardt DT, Sørensen ES. Cell type-specific post-translational modifications of mouse osteopontin are associated with different adhesive properties. J Biol Chem 2007; 282:19463-72. [PMID: 17500062 DOI: 10.1074/jbc.m703055200] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Osteopontin (OPN) is a highly modified integrin-binding protein found in all body fluids. Expression of OPN is strongly correlated with poor prognosis in many different human cancers, suggesting an important but poorly understood role for this protein in tumorigenesis and metastasis. The protein exists in a number of different isoforms differing in the degree of post-translational modifications that are likely to exhibit different functional properties. This study examines for the first time the post-translational modifications of OPN from transformed cells and the effects of these modifications on cell biology. We have characterized the complete phosphorylation and glycosylation patterns of OPN expressed by murine ras-transformed fibroblasts (FbOPN) and differentiating osteoblasts (ObOPN) by a combination of mass spectrometric analyses and Edman degradation. Mass spectrometric analysis showed masses of 34.9 and 35.9 kDa for FbOPN and ObOPN, respectively. Enzymatic dephosphorylation, sequence, and mass analyses demonstrated that FbOPN contains approximately four phosphate groups distributed over 16 potential phosphorylation sites, whereas ObOPN contains approximately 21 phosphate groups distributed over 27 sites. Five residues are O-glycosylated in both isoforms. These residues are fully modified in FbOPN, whereas one site is partially glycosylated in ObOPN. Although both forms of OPN mediated robust integrin-mediated adhesion of mouse ras-transformed fibroblasts, the less phosphorylated FbOPN mediated binding of MDA-MD-435 human tumor cells almost 6-fold more than the heavy phosphorylated ObOPN. These results strongly support the hypothesis that the degree of phosphorylation of OPN produced by different cell types can regulate its function.
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Affiliation(s)
- Brian Christensen
- Protein Chemistry Laboratory, Department of Molecular Biology, University of Aarhus, DK-8000 Aarhus C, Denmark
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19
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Graessmann M, Berg B, Fuchs B, Klein A, Graessmann A. Chemotherapy resistance of mouse WAP-SVT/t breast cancer cells is mediated by osteopontin, inhibiting apoptosis downstream of caspase-3. Oncogene 2006; 26:2840-50. [PMID: 17160024 DOI: 10.1038/sj.onc.1210096] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Impairment of the complex regulatory network of cell death and survival is frequently the reason for therapy resistance of breast cancer cells and a major cause of tumor progression. We established two independent cell lines from a fast growing mouse breast tumor (WAP-SVT/t transgenic animal). Cells from one line (ME-A cells) are sensitive to apoptotic stimuli such as growth factor depletion or treatment with antitumor agents (e.g. doxorubicin). Cells from the second line (ME-C cells), which carry a missense mutation at the p53 codon 242, are very insensitive to apoptotic stimuli. Co-cultivation experiments revealed that the ME-C cells mediate cell death resistance to the ME-A cells. Microarray and Western blot analysis showed that osteopontin (OPN) is selectively overexpressed by the ME-C cells. This glycoprotein is the most abundant protein secreted by the ME-C cells and we obtained strong indications that OPN is the main antiapoptotic factor. However, the OPN containing ME-C cell medium does not alter the expression level of pro- or antiapoptotic genes or known inhibitors of apoptosis (IAPs). Its signaling involves mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK)1/2 as the kinase inhibitor PD98059 restores apoptosis but not the Akt inhibitor. In the ME-A cells, mitochondrial cytochrome c release occurs with and without external apoptotic stimuli. OPN containing ME-C cell medium does not prevent the mitochondrial cytochrome c release and caspase-9 processing. In serum starved ME-A cells, the OPN containing ME-C cell medium prevents caspase-3 activation. However, in doxorubicin-treated cells, although apoptosis is blocked, it does not inhibit caspase-3. This indicates that the ME-A cells distinguish between the initial apoptotic stimuli and that the cells possess a further uncharacterized control element acting downstream from caspase-3.
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MESH Headings
- Animals
- Antibiotics, Antineoplastic/pharmacology
- Antigens, Polyomavirus Transforming/genetics
- Apoptosis/genetics
- Caspase 3/physiology
- Culture Media, Serum-Free/pharmacology
- Cytochromes c/metabolism
- Doxorubicin/pharmacology
- Drug Resistance, Neoplasm/genetics
- JNK Mitogen-Activated Protein Kinases/metabolism
- Mammary Neoplasms, Animal/genetics
- Mammary Neoplasms, Animal/metabolism
- Mammary Neoplasms, Animal/pathology
- Mice
- Mice, Transgenic
- Milk Proteins/genetics
- Mitochondria/metabolism
- Models, Biological
- Osteopontin/metabolism
- Osteopontin/physiology
- Tumor Cells, Cultured
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Affiliation(s)
- M Graessmann
- Institut für Molekularbiologie und Bioinformatik, Charité Unversitätsmedizin Berlin, Berlin, Germany.
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20
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Rangaswami H, Bulbule A, Kundu GC. Nuclear factor inducing kinase: a key regulator in osteopontin- induced MAPK/IkappaB kinase dependent NF-kappaB-mediated promatrix metalloproteinase-9 activation. Glycoconj J 2006; 23:221-32. [PMID: 16691505 DOI: 10.1007/s10719-006-7927-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Osteopontin (OPN) is a secreted, non-collagenous, sialic-acid rich, glycosylated adhesive phospho- protein. Several highly metastatic transformed cells synthesized a higher level of OPN compared with non-tumorigenic cells. We have recently reported that OPN induces nuclear factor-kappaB (NF-kappaB)-mediated promatrix metalloproteinase-2 activation through IkappaBalpha/IKK signaling pathways. However, the molecular mechanism(s) by which OPN regulates pro-matrix metalloproteinase-9 (pro-MMP-9) activation and involvement of upstream kinases in regulation of these processes that ultimately control cell motility and tumor growth in murine melanoma cells are not well defined. Here we report that OPN induces alphavbeta3 integrin-mediated phosphorylation and activation of nuclear factor inducing kinase (NIK) and enhances the interaction between phosphorylated NIK and IkappaBalpha kinase alpha/beta (IKKalpha/beta) in B16F10 cells. Moreover, NIK is involved in OPN-induced phosphorylations of MEK-1 and ERK1/2 in these cells. OPN induces NIK-dependent NF-kappaB activation through ERK/IKKalpha/beta-mediated pathways. Furthermore, OPN enhances NIK-regulated urokinase-type plasminogen activator (uPA) secretion, uPA-dependent pro-MMP-9 activation, and cell motility. Pretreatment of cells with anti-MMP-2 antibody along with anti-MMP-9 antibody drastically inhibited the OPN-induced cell migration and chemoinvasion, whereas cells pretreated with anti-MMP-2 antibody had no effect on OPN-induced pro-MMP-9 activation suggesting that OPN induces pro-MMP-2 and pro-MMP-9 activations through two distinct pathways. Taken together, NIK acts as crucial regulator in OPN-induced MAPK/IKK-mediated NF-kappaB-dependent uPA secretion and MMP-9 activation thereby controlling melanoma cell motility and chemoinvasion.
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Affiliation(s)
- Hema Rangaswami
- National Center for Cell Science (NCCS), Pune, 411 007, India
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21
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Christensen B, Nielsen M, Haselmann K, Petersen T, Sørensen E. Post-translationally modified residues of native human osteopontin are located in clusters: identification of 36 phosphorylation and five O-glycosylation sites and their biological implications. Biochem J 2005; 390:285-92. [PMID: 15869464 PMCID: PMC1184582 DOI: 10.1042/bj20050341] [Citation(s) in RCA: 183] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OPN (osteopontin) is an integrin-binding highly phosphorylated glycoprotein, recognized as a key molecule in a multitude of biological processes such as bone mineralization, cancer metastasis, cell-mediated immune response, inflammation and cell survival. A significant regulation of OPN function is mediated through PTM (post-translational modification). Using a combination of Edman degradation and MS analyses, we have characterized the complete phosphorylation and glycosylation pattern of native human OPN. A total of 36 phosphoresidues have been localized in the sequence of OPN. There are 29 phosphorylations (Ser8, Ser10, Ser11, Ser46, Ser47, Thr50, Ser60, Ser62, Ser65, Ser83, Ser86, Ser89, Ser92, Ser104, Ser110, Ser113, Thr169, Ser179, Ser208, Ser218, Ser238, Ser247, Ser254, Ser259, Ser264, Ser275, Ser287, Ser292 and Ser294) located in the target sequence of MGCK (mammary gland casein kinase) also known as the Golgi kinase (S/T-X-E/S(P)/D). Six phosphorylations (Ser101, Ser107, Ser175, Ser199, Ser212 and Ser251) are located in the target sequence of CKII (casein kinase II) [S-X-X-E/S(P)/D] and a single phosphorylation, Ser203, is not positioned in the motif of either MGCK or CKII. The 36 phosphoresidues represent the maximal degree of modification since variability at many sites was seen. Five threonine residues are O-glycosylated (Thr118, Thr122, Thr127, Thr131 and Thr136) and two potential sites for N-glycosylation (Asn63 and Asn90) are not occupied in human milk OPN. The phosphorylations are arranged in clusters of three to five phosphoresidues and the regions containing the glycosylations and the RGD (Arg-Gly-Asp) integrin-binding sequence are devoid of phosphorylations. Knowledge about the positions and nature of PTMs in OPN will allow a rational experimental design of functional studies aimed at understanding the structural and functional interdependences in diverse biological processes in which OPN is a key molecule.
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Affiliation(s)
- Brian Christensen
- *Protein Chemistry Laboratory, Department of Molecular Biology, Science Park, University of Aarhus, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Mette S. Nielsen
- *Protein Chemistry Laboratory, Department of Molecular Biology, Science Park, University of Aarhus, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Kim F. Haselmann
- †Department of Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Torben E. Petersen
- *Protein Chemistry Laboratory, Department of Molecular Biology, Science Park, University of Aarhus, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Esben S. Sørensen
- *Protein Chemistry Laboratory, Department of Molecular Biology, Science Park, University of Aarhus, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
- To whom correspondence should be addressed (email )
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22
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Vejda S, Piwocka K, McKenna SL, Cotter TG. Autocrine secretion of osteopontin results in degradation of IkappaB in Bcr-Abl-expressing cells. Br J Haematol 2005; 128:711-21. [PMID: 15725094 DOI: 10.1111/j.1365-2141.2004.05355.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Osteopontin has been identified as a marker of metastasis formation and its increased expression has been correlated with the malignancy of cancer. In this study we provide evidence that increased expression of osteopontin may also be associated with progression of Bcr-Abl-expressing leukaemia cells. The Bcr-Abl fusion protein, generated by the Philadelphia translocation, is the hallmark of chronic myeloid leukaemia (CML). CML exhibits clinically distinct phases. Advanced disease shows defective differentiation, bone marrow infiltration and drug resistance. The critical signalling mediating this disease progression is unknown. Increased aggressiveness of the disease has been correlated with elevated amounts of Bcr-Abl. We generated a 32D cell line model to study the consequences of different expression levels of Bcr-Abl. Osteopontin was identified by microarray analysis as highly upregulated in cells expressing elevated amounts of Bcr-Abl. Moreover, in high Bcr-Abl expressing cells, an additional 50 kDa isoform of osteopontin was detected. It was found that this protein was secreted and that myeloid progenitor cells also expressed appropriate receptors for autocrine activation. We demonstrated that secretion of osteopontin resulted in enhanced degradation of I kappa B, the inhibitor of NF-kappa B. These data indicate a novel consequence of elevated Bcr-Abl expression, which may contribute to the progression of CML.
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Affiliation(s)
- Susanne Vejda
- Cell Development and Disease Laboratory, Department of Biochemistry, BioSciences Institute, University College Cork, Cork, Ireland
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23
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Razzouk S, Brunn JC, Qin C, Tye CE, Goldberg HA, Butler WT. Osteopontin posttranslational modifications, possibly phosphorylation, are required for in vitro bone resorption but not osteoclast adhesion. Bone 2002; 30:40-7. [PMID: 11792563 DOI: 10.1016/s8756-3282(01)00637-8] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Osteopontin (OPN), a phosphorylated bone matrix glycoprotein, is an Arg-Gly-Asp (RGD)-containing protein that interacts with integrins and promotes in vitro attachment of a number of cell types, including osteoclasts. Gene knockout experiments support the idea that OPN is important in osteoclastic activity. We hypothesize that posttranslational modifications (PTMs) of OPN can influence its physiological function. Previous studies have suggested that phosphorylation of OPN and bone sialoprotein (BSP) is necessary for promoting osteoclast adhesion. However, no reports have explored the importance of phosphoserines and other PTMs in OPN-promoted bone resorption. To study this question, we determined the activities of different forms of OPN and BSP in three in vitro assays: attachment of osteoclasts; formation of actin rings; and bone resorption. For each assay, cells were incubated for 4-24 h, in the presence or absence of RGDS or RGES peptides, to test the involvement of integrin binding. In addition to OPN, activities of milk OPN (fully phosphorylated) and recombinant OPN (rOPN, no phosphate) were compared. We purified two forms of OPN (OPN-2 and OPN-5), which differ in the level of phosphorylation, and compared their activities. For comparison, the activities of BSP and recombinant BSP (rBSP) were determined. All forms of OPN, including rOPN, significantly increased attachment of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts. BSP and rBSP also promoted cell attachment. After 4 h of incubation, the proportion of cells with actin rings was increased with OPN, milk OPN, and BSP. In the presence of RGDS peptide, osteoclast retraction and the disruption of actin rings were observed, whereas no effect was seen with RGES. In the resorption assay, the number of pits and the total resorbed area per slice were increased in the presence of OPN, milk OPN, and BSP. As in other assays, the OPN enhancement of resorption was inhibited by RGDS, but not RGES, peptides. Significantly, rOPN and rBSP did not promote bone resorption. OPN-5 promoted resorption to a greater extent than OPN-2, and milk OPN significantly stimulated resorption to a greater extent than OPN. Our data suggest that: (1) the RGD sequence of OPN is essential in OPN-mediated cell attachment, actin ring formation, and bone resorption; and (2) some form of PTM, possibly phosphorylation, is necessary for in vitro osteoclastic bone resorption, but not for cell attachment and actin ring formation.
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Affiliation(s)
- S Razzouk
- Department of Basic Sciences, Dental Branch, University of Texas-Houston Health Science Center, Houston, TX 77030, USA
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24
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Weber GF. The metastasis gene osteopontin: a candidate target for cancer therapy. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1552:61-85. [PMID: 11825687 DOI: 10.1016/s0304-419x(01)00037-3] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Malignant tumors are characterized by dysregulated growth control, overcoming of replicative senescence, and metastasis formation. Current therapeutic regimens mostly exert their effects through inhibition of cell cycle progression, leaving two major components of transformation untouched. The cytokine osteopontin is essential for the dissemination of various cancers. Past research has implied several modes in which osteopontin and its main receptors on tumor cells can be suppressed. Osteopontin expression is inhibitable on the levels of gene transcription and the RNA message, and the osteopontin protein can be blocked with antibodies or synthetic peptides. The osteopontin receptor CD44 has been targeted by diverse therapeutic strategies, including cytotoxic and immunotherapeutic approaches. The receptor integrin alpha(V)beta(3) contributes not only to tumor cell dissemination, but also to angiogenesis and osteolysis in bone metastases. Small molecule inhibitors of this receptor are under study as drug candidates. Because receptors and cytokine ligands that mediate metastasis formation are sparsely expressed in the adult healthy organism and are more readily reached by pharmaceuticals than intracellular drug targets they may represent a particularly suitable focus for therapeutic intervention.
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Affiliation(s)
- G F Weber
- Department of Radiation Oncology, New England Medical Center and Tufts University Medical School, 750 Washington Street, NEMC #824, Boston, MA 02111, USA.
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25
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Tuck AB, Chambers AF. The role of osteopontin in breast cancer: clinical and experimental studies. J Mammary Gland Biol Neoplasia 2001; 6:419-29. [PMID: 12013531 DOI: 10.1023/a:1014734930781] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Osteopontin (OPN) is a secreted, integrin-binding protein which has been implicated in cancer, as well as other pathologies and some aspects of normal development. Here we focus on the role of OPN in breast cancer. We describe studies that have shown that OPN plays a role in normal mammary gland development as well as in progression of breast cancer. We also summarize studies that have shown that OPN can play a functional role in malignancy of breast cancer. At least some of these effects are mediated by specific cell surface integrins (alpha(v)beta3 vs. alpha(v)beta1 and alpha(v)beta5) and lead to increased cell migration, activation of growth factor/receptor pathways (e.g. HGF and EGF), and increased proteolytic enzyme activity (e.g. uPA). We also summarize clinical studies that show that OPN levels in tumors and blood are elevated in women with metastatic breast cancer and may offer promise as prognostic markers in breast cancer.
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Affiliation(s)
- A B Tuck
- Department of Oncology, University of Western Ontario, London, Canada
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26
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Sodek J, Ganss B, McKee MD. Osteopontin. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 2001; 11:279-303. [PMID: 11021631 DOI: 10.1177/10454411000110030101] [Citation(s) in RCA: 829] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Osteopontin (OPN) is a highly phosphorylated sialoprotein that is a prominent component of the mineralized extracellular matrices of bones and teeth. OPN is characterized by the presence of a polyaspartic acid sequence and sites of Ser/Thr phosphorylation that mediate hydroxyapatite binding, and a highly conserved RGD motif that mediates cell attachment/signaling. Expression of OPN in a variety of tissues indicates a multiplicity of functions that involve one or more of these conserved motifs. While the lack of a clear phenotype in OPN "knockout" mice has not established a definitive role for OPN in any tissue, recent studies have provided some novel and intriguing insights into the versatility of this enigmatic protein in diverse biological events, including developmental processes, wound healing, immunological responses, tumorigenesis, bone resorption, and calcification. The ability of OPN to stimulate cell activity through multiple receptors linked to several interactive signaling pathways can account for much of the functional diversity. In this review, we discuss the structural features of OPN that relate to its function in the formation, remodeling, and maintenance of bones and teeth.
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Affiliation(s)
- J Sodek
- MRC Group in Periodontal Physiology, Faculty of Dentistry, University of Toronto, ON, Canada.
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27
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Metzler DE, Metzler CM, Sauke DJ. Lipids, Membranes, and Cell Coats. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50011-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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28
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Weber GF, Ashkar S. Molecular mechanisms of tumor dissemination in primary and metastatic brain cancers. Brain Res Bull 2000; 53:421-4. [PMID: 11136998 DOI: 10.1016/s0361-9230(00)00379-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cancer is characterized by dysregulated growth control, overcoming of replicative senescence, and metastasis formation. Tumor dissemination distinguishes malignant from benign neoplasms and is mediated by homing receptors, their ligands, and proteinases. The homing receptor CD44 is frequently expressed on primary brain tumors and brain metastases. Its engagement by osteopontin physiologically induces macrophage chemotaxis, a mechanism that may be utilized by metastatic brain tumors in the process of dissemination. In host defense, osteopontin and its receptors, CD44 and integrin alpha(V)beta(3), play key roles in mediating delayed type hypersensitivity responses by activating macrophages to induce Th1 cytokines while inhibiting Th2 cytokines. Other metastasis associated gene products similarly contribute to host defenses. Hence, cancer spread is regulated by a set of developmentally non-essential genes which physiologically mediate stress responses, inflammation, wound healing, and neovascularization. Function of the relevant gene products is extensively modified post-transcriptionally and their dysregulation in cancer occurs on the levels of expression and splicing. Consistent patterns of organ preference by malignancies of particular tissue origin suggest a necessary connection between loss of growth control and senescence genes and expression of genes mediating the dissemination of tumor cells.
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Affiliation(s)
- G F Weber
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA, USA.
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29
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Matsuura T, Hosokawa R, Okamoto K, Kimoto T, Akagawa Y. Diverse mechanisms of osteoblast spreading on hydroxyapatite and titanium. Biomaterials 2000; 21:1121-7. [PMID: 10817264 DOI: 10.1016/s0142-9612(99)00264-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Hydroxyapatite (HA) is an osteoconductive implant material. We previously demonstrated that RGD peptides regulate the spreading of HOS cells on HA but not on titanium, speculating that the osteoconductivity of HA might be attributed to this RGD domain-dependent spreading of osteoblasts. To confirm this hypothesis, the molecules which regulate the spreading of HOS cells on HA and on titanium were investigated. The 50% effective dose (ED50) of RGD peptide for the spreading on HA was five fold lower comparing to titanium. Anti-alphaV integrin antibody, vitronectin, and fibronectin inhibited the spreading on HA but not on titanium. In Western blot analysis, vitronectin and fibronectin were found in components adsorbed to HA but not to titanium. Taken together, the spreading of HOS cells on HA but not on titanium requires the interaction of alphaV integrin and its ligands. The ED50 of the RGD peptides on titanium but not on HA was remarkably reduced by neuraminidase treatment, that by itself could not inhibit the spreading on both materials. This phenomenon suggests that RGD domain and sialic acid cooperatively but not independently mediate the spreading of HOS cells on titanium. Collectively, the molecules regulating the spreading on HA are apparently different from those on titanium. The spreading of osteoblasts mediated by RGD domain of vitronectin and fibronectin might contribute to the osteoconductive ability of HA.
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Affiliation(s)
- T Matsuura
- Dental Research Center, University of North Carolina at Chapel Hill, 27599-7450, USA.
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30
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Abstract
BACKGROUND We studied the role of cell surface sialic acid in the adherence of calcium oxalate monohydrate (COM) crystals to Madin-Darby canine kidney (MDCK) cells. METHODS Studies were performed with undifferentiated (crystal-binding) cells in subconfluent cultures and maturated (noncrystal-binding) cells in confluent cultures. Lectins were used to study the emergence and abundance of oligosaccharides at the cell surface during epithelial development. The effect of neuraminidase treatment on crystal binding was studied with [14C]COM crystals, and the enzyme-induced release of cell surface-associated sialic acid molecules was monitored by labeling the cells metabolically with [3H]glucosamine. RESULTS Binding studies with lectins derived from Maackia Amurensis II (MALII) and Sambucus Nigra (SNA) demonstrated that the cells expressed terminal sialic acids attached to penultimate galactose through alpha 2,3 and alpha 2,6 bonds at different stages of epithelial development. Neuraminidase treatment strongly reduced the affinity of the cell surface for COM crystals in subconfluent cultures. Nevertheless, neuraminidase cleaved more sialic acids from cells in confluent cultures than from those in subconfluent cultures. Peanut agglutinin (PNA), which binds only to sialylated terminal galactose units, adhered to developing but not to maturated cells, unless the latter were pretreated with neuraminidase. Both results indicate that the surface of maturated MDCK cells is more heavily sialylated than that of undifferentiated cells. Free sialic acid molecules showed little or no affinity for COM crystals and did not affect the adherence of the crystals to undifferentiated cells. CONCLUSIONS There are at least two models that may explain these results. First, sialic acids are presented at the surface of immature cells in an orientation that specifically matches crystal surface characteristics favoring crystal-cell interactions. Second, sialic acid molecules are not directly associated with the crystals, but may be involved in the exposure of another crystal binding molecule at the cell surface.
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Affiliation(s)
- C F Verkoelen
- Erasmus Urological Stone Treatment and Research (Eurostarr), Erasmus University, Rotterdam, The Netherlands.
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Caltabiano S, Hum WT, Attwell GJ, Gralnick DN, Budman LJ, Cannistraci AM, Bex FJ. The integrin specificity of human recombinant osteopontin. Biochem Pharmacol 1999; 58:1567-78. [PMID: 10535747 DOI: 10.1016/s0006-2952(99)00251-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The ability of full-length human recombinant osteopontin (OPN) to support the adhesion of various alphav integrin-expressing cell lines was determined in order to characterize its integrin selectivity. The identity of this protein was assessed by cDNA sequence and mass spectroscopic analysis, and confirmed as full-length OPN. Neither the human embryonic kidney 293 cell line, which expresses the alphavbeta1 integrin, nor the human colonic adenocarcinoma HT-29 cell line, which expresses the alphavbeta5 integrin, were able to adhere to OPN; both of these cell lines are deficient in the beta3 subunit. In contrast, an alphavbeta3 integrin-expressing cell line, SK-MEL-24, was able to adhere to OPN in an arginine-glycine-aspartic acid dependent manner. In addition, this OPN-mediated cellular adhesion was completely blocked with an anti-alphavbeta3 integrin antibody (LM609), confirming that only the alphavbeta3 integrin mediated this cellular adhesion. These data demonstrate that, at least among the alphav integrins, only the alphavbeta3 is able to support cellular adhesion to osteopontin. This finding may have implications for the design of therapeutics targeting OPN-integrin interactions.
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Affiliation(s)
- S Caltabiano
- Department of Bone Metabolism and Osteoporosis Research, Wyeth-Ayerst Research, Philadelphia 19101, USA.
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Tuck AB, Arsenault DM, O'Malley FP, Hota C, Ling MC, Wilson SM, Chambers AF. Osteopontin induces increased invasiveness and plasminogen activator expression of human mammary epithelial cells. Oncogene 1999; 18:4237-46. [PMID: 10435636 DOI: 10.1038/sj.onc.1202799] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Osteopontin (OPN) has been associated with enhanced malignancy in breast cancer, but its functional role in this disease is poorly understood. To study the effect of OPN on cellular invasiveness, basal OPN expression was first assessed in members of a progression series of human mammary epithelial cell lines (21PT: immortalized, non-tumorigenic; 21NT: weakly tumorigenic; 21MT-1: tumorigenic, weakly metastatic; MDA-MB-435 cells: tumorigenic, highly metastatic). The two lines which expressed lowest basal levels of OPN (21PT, 21NT) were then examined for up-regulation of invasive behavior in response to exogenous or transfected (endogenous) OPN. Both 21PT and 21NT showed increased invasiveness through Matrigel when human recombinant (hr)OPN was added to the lower chamber of transwells. Both also showed a cell migration response to hrOPN. Populations of 21PT and 21NT cells stably transfected with an OPN-expression vector showed higher levels of cell invasiness than control vector transfectants. Examination of transfectants for mRNA of a number of secreted proteases showed that only urokinase-type plasminogen activator (uPA) expression was closely associated with OPN expression and cellular invasiveness. Treatment of the parental 21PT and 21NT cells with exogenous hrOPN resulted in increased uPA mRNA expression and increased urokinase activity of the conditioned media. Both increased cell migration and induction of uPA expression are thus potential mechanisms of increased invasiness of breast epithelial cells in response to OPN.
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Affiliation(s)
- A B Tuck
- Department of Pathology, London Health Sciences Centre, University of Western Ontario, Canada
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Liaw L, Crawford HC. Functions of the extracellular matrix and matrix degrading proteases during tumor progression. Braz J Med Biol Res 1999; 32:805-12. [PMID: 10454737 DOI: 10.1590/s0100-879x1999000700002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Cell interactions with extracellular matrices are important to pathological changes that occur during cell transformation and tumorigenesis. Several extracellular matrix proteins including fibronectin, thrombospondin-1, laminin, SPARC, and osteopontin have been suggested to modulate tumor phenotype by affecting cell migration, survival, or angiogenesis. Likewise, proteases including the matrix metalloproteinases (MMPs) are understood to not only facilitate migration of cells by degradation of matrices, but also to affect tumor formation and growth. We have recently demonstrated an in vivo role for the RGD-containing protein, osteopontin, during tumor progression, and found evidence for distinct functions in the host versus the tumor cells. Because of the compartmentalization and temporal regulation of MMP expression, it is likely that MMPs may also function dually in host stroma and the tumor cell. In addition, an important function of proteases appears to be not only degradation, but also cleavage of matrix proteins to generate functionally distinct fragments based on receptor binding, biological activity, or regulation of growth factors.
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Affiliation(s)
- L Liaw
- Center for Molecular Medicine, Maine Medical Center Research Institute, South Portland 04106, USA.
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Keppler OT, Hinderlich S, Langner J, Schwartz-Albiez R, Reutter W, Pawlita M. UDP-GlcNAc 2-epimerase: a regulator of cell surface sialylation. Science 1999; 284:1372-6. [PMID: 10334995 DOI: 10.1126/science.284.5418.1372] [Citation(s) in RCA: 242] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Modification of cell surface molecules with sialic acid is crucial for their function in many biological processes, including cell adhesion and signal transduction. Uridine diphosphate-N-acetylglucosamine 2-epimerase (UDP-GlcNAc 2-epimerase) is an enzyme that catalyzes an early, rate-limiting step in the sialic acid biosynthetic pathway. UDP-GlcNAc 2-epimerase was found to be a major determinant of cell surface sialylation in human hematopoietic cell lines and a critical regulator of the function of specific cell surface adhesion molecules.
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Affiliation(s)
- O T Keppler
- Applied Tumor Virology Program, Tumor Immunology Program, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
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Abstract
Osteopontin is a secreted glycoprotein with adhesive and migratory functions. Cellular interactions with osteopontin are mediated through integrin receptors which recognize the RGD domain. Recently, CD44, a non-integrin, multifunctional adhesion molecule was identified as an osteopontin receptor. CD44 is a ubiquitous surface molecule that exists as a number of different isoforms, generated by alternative splicing. To analyze which forms of CD44 mediate binding to osteopontin, we used the standard form of CD44 as CD44-human immunoglobulin fusion proteins and several splice variants in enzyme-linked immunosorbant assays. Multiple preparations of osteopontin were used including native osteopontin derived from smooth muscle cells, human urinary osteopontin, full-length recombinant osteopontin, and two recombinant osteopontin fragments expected to be formed following thrombin cleavage. Our data show that although the CD44-hlg fusion proteins could interact with hyaluronic acid as expected, there was no interaction between CD44H, CD44E, CD44v3,v8-v10, or CD44v3 with osteopontin. These studies suggest that CD44-osteopontin interactions may not be common in vivo and may be limited to a specific CD44 isoform(s), and/or a particular modified form of osteopontin.
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Affiliation(s)
- L L Smith
- Department of Pathology, University of Washington, Seattle 98195, USA
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Denhardt DT, Noda M. Osteopontin expression and function: Role in bone remodeling. J Cell Biochem 1998; 72 Suppl 30-31:92-102. [DOI: 10.1002/(sici)1097-4644(1998)72:30/31+<92::aid-jcb13>3.0.co;2-a] [Citation(s) in RCA: 290] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/1998] [Accepted: 09/22/1998] [Indexed: 01/13/2023]
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