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Mackay S, Hitefield NL, Oduor IO, Roberts AB, Burch TC, Lance RS, Cunningham TD, Troyer DA, Semmes OJ, Nyalwidhe JO. Site-Specific Intact N-Linked Glycopeptide Characterization of Prostate-Specific Membrane Antigen from Metastatic Prostate Cancer Cells. ACS OMEGA 2022; 7:29714-29727. [PMID: 36061737 PMCID: PMC9435049 DOI: 10.1021/acsomega.2c02265] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 08/04/2022] [Indexed: 06/15/2023]
Abstract
The composition of N-linked glycans that are conjugated to the prostate-specific membrane antigen (PSMA) and their functional significance in prostate cancer progression have not been fully characterized. PSMA was isolated from two metastatic prostate cancer cell lines, LNCaP and MDAPCa2b, which have different tissue tropism and localization. Isolated PSMA was trypsin-digested, and intact glycopeptides were subjected to LC-HCD-EThcD-MS/MS analysis on a Tribrid Orbitrap Fusion Lumos mass spectrometer. Differential qualitative and quantitative analysis of site-specific N-glycopeptides was performed using Byonic and Byologic software. Comparative quantitative analysis demonstrates that multiple glycopeptides at asparagine residues 51, 76, 121, 195, 336, 459, 476, and 638 were in significantly different abundance in the two cell lines (p < 0.05). Biochemical analysis using endoglycosidase treatment and lectin capture confirm the MS and site occupancy data. The data demonstrate the effectiveness of the strategy for comprehensive analysis of PSMA glycopeptides. This approach will form the basis of ongoing experiments to identify site-specific glycan changes in PSMA isolated from disease-stratified clinical samples to uncover targets that may be associated with disease progression and metastatic phenotypes.
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Affiliation(s)
- Stephen Mackay
- Leroy
T. Canoles Jr. Cancer Research Center, Eastern
Virginia Medical School, Norfolk, Virginia 23507, United States
- Department
of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, United States
- University
of North Carolina, Chapel Hill, North Carolina 27516, United States
| | - Naomi L. Hitefield
- Leroy
T. Canoles Jr. Cancer Research Center, Eastern
Virginia Medical School, Norfolk, Virginia 23507, United States
- Department
of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, United States
- University
of Georgia, Athens, Georgia 30602, United
States
| | - Ian O. Oduor
- Leroy
T. Canoles Jr. Cancer Research Center, Eastern
Virginia Medical School, Norfolk, Virginia 23507, United States
| | - Autumn B. Roberts
- Leroy
T. Canoles Jr. Cancer Research Center, Eastern
Virginia Medical School, Norfolk, Virginia 23507, United States
- Department
of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, United States
| | - Tanya C. Burch
- Leroy
T. Canoles Jr. Cancer Research Center, Eastern
Virginia Medical School, Norfolk, Virginia 23507, United States
- Department
of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, United States
| | - Raymond S. Lance
- Leroy
T. Canoles Jr. Cancer Research Center, Eastern
Virginia Medical School, Norfolk, Virginia 23507, United States
- Spokane
Urology, Spokane, Washington 99202, United States
| | - Tina D. Cunningham
- School of
Health Professions, Eastern Virginia Medical
School, Norfolk, Virginia 23507, United States
| | - Dean A. Troyer
- Leroy
T. Canoles Jr. Cancer Research Center, Eastern
Virginia Medical School, Norfolk, Virginia 23507, United States
- Department
of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, United States
| | - Oliver J. Semmes
- Leroy
T. Canoles Jr. Cancer Research Center, Eastern
Virginia Medical School, Norfolk, Virginia 23507, United States
- Department
of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, United States
| | - Julius O. Nyalwidhe
- Leroy
T. Canoles Jr. Cancer Research Center, Eastern
Virginia Medical School, Norfolk, Virginia 23507, United States
- Department
of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, United States
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2
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Tao R, Ni Z, Liu C, Zhu M, Ji X, Chen X, Shen J, Tu S. Expression, purification and identification of an immunogenic fragment in the ectodomain of prostate-specific membrane antigen. Exp Ther Med 2016; 11:747-752. [PMID: 26997988 PMCID: PMC4774373 DOI: 10.3892/etm.2016.3005] [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: 04/03/2015] [Accepted: 11/25/2015] [Indexed: 11/21/2022] Open
Abstract
The present study aimed to identify, express and purify an immunogenic fragment in the ectodomain of prostate-specific membrane antigen (PSMA) within a fusion protein. The PSMA amino acid sequence published in National Center for Biotechnology Information GenBank was used to determine sequence homology and immunogenic index analyses, additionally using BLASTN, Protean and ExPASy software to predict the polypeptide sequences of immunogenic epitopes. The gene sequence encoding the ectodomain of the polypeptide immunogenic fragments, containing the identified immunogenic epitopes, was generated using whole-gene synthesis. Prokaryotic expression vector pET-32a-r-ectodomain-PSMA was constructed and the recombinant plasmids were transformed into competent BL21 (DE3) Escherichia coli, which was followed by induction of recombinant protein expression using isopropyl-β-D-thiogalactopyranoside. Fusion proteins were isolated and purified using affinity chromatography and their immune activity was subsequently investigated using western blot analysis. Purified protein was used to immunize BALB/c mice in order to generate polyclonal antibodies, and the binding of polyclonal antibodies to prostate cancer cell lines in vitro was evaluated using flow cytometry. A total of 3 polypeptide fragments with high specificity were identified following analysis using numerous software packages, and the gene sequences encoding regions containing the 2 most immunogenic fragments were synthesized and successfully inserted into the prokaryotic expression vector pET-32a-r-ectodomain-PSMA. The recombinant PSMA protein fragment had a molecular weight of ~50 kDa and 95% purity. Western blot analysis revealed that the r-ectodomain-PSMA fusion protein specifically bound to the anti-PSMA ectodomain monoclonal antibody. Flow cytometry demonstrated that polyclonal antibodies raised against these recombinant proteins could specifically bind to PSMA-positive LNCaP cells, but not to PSMA-negative PC-3 cells. An immunogenic fragment in the ectodomain of PSMA was successfully expressed and purified. The present study, therefore, provides a basis for the preparation of an anti-PSMA small humanized monoclonal antibody.
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Affiliation(s)
- Rong Tao
- Department of Nuclear Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, P.R. China
| | - Zhenhua Ni
- Department of Nuclear Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, P.R. China
| | - Chong Liu
- Department of Nuclear Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, P.R. China
| | - Min Zhu
- Department of Nuclear Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, P.R. China
| | - Xiaowen Ji
- Department of Nuclear Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, P.R. China
| | - Xuemin Chen
- Department of Nuclear Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, P.R. China
| | - Jiangfan Shen
- Department of Nuclear Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, P.R. China
| | - Shaohua Tu
- Department of Nuclear Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, P.R. China
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3
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Rockey WM, Hernandez FJ, Huang SY, Cao S, Howell CA, Thomas GS, Liu XY, Lapteva N, Spencer DM, McNamara JO, Zou X, Chen SJ, Giangrande PH. Rational truncation of an RNA aptamer to prostate-specific membrane antigen using computational structural modeling. Nucleic Acid Ther 2012; 21:299-314. [PMID: 22004414 DOI: 10.1089/nat.2011.0313] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RNA aptamers represent an emerging class of pharmaceuticals with great potential for targeted cancer diagnostics and therapy. Several RNA aptamers that bind cancer cell-surface antigens with high affinity and specificity have been described. However, their clinical potential has yet to be realized. A significant obstacle to the clinical adoption of RNA aptamers is the high cost of manufacturing long RNA sequences through chemical synthesis. Therapeutic aptamers are often truncated postselection by using a trial-and-error process, which is time consuming and inefficient. Here, we used a "rational truncation" approach guided by RNA structural prediction and protein/RNA docking algorithms that enabled us to substantially truncateA9, an RNA aptamer to prostate-specific membrane antigen (PSMA),with great potential for targeted therapeutics. This truncated PSMA aptamer (A9L; 41mer) retains binding activity, functionality, and is amenable to large-scale chemical synthesis for future clinical applications. In addition, the modeled RNA tertiary structure and protein/RNA docking predictions revealed key nucleotides within the aptamer critical for binding to PSMA and inhibiting its enzymatic activity. Finally, this work highlights the utility of existing RNA structural prediction and protein docking techniques that may be generally applicable to developing RNA aptamers optimized for therapeutic use.
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Affiliation(s)
- William M Rockey
- Department of Radiation Oncology, University of Iowa, Iowa City, USA
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4
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Chen X, Dong Y, Fan L, Yang D, Zhang M. Resonance scattering method for the ultrasensitive determination of peptides using semiconductor nanocrystals. Anal Chim Acta 2007; 597:300-5. [PMID: 17683743 DOI: 10.1016/j.aca.2007.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2007] [Revised: 04/22/2007] [Accepted: 07/02/2007] [Indexed: 11/24/2022]
Abstract
Resonance light scattering (RLS) of the functionalized ZnS nanocrystals-peptides system and its analytical application have been studied. The RLS intensity can be efficiently enhanced when various peptides were added. The mechanism of the RLS enhancement of ZnS nanocrystals was discussed. The change of RLS intensity was in proportion to the concentration of peptides. The limits of detection were in range of 2.8-5.7 ng mL(-1). Application results to synthetic samples showed simplicity, rapidity, high sensitivity and satisfactory reproducibility of the presented method. Measurements of real samples also give satisfactory results which were in good agreement with those obtained using high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrography (LC-MS) methods.
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Affiliation(s)
- Xudong Chen
- School of Chemistry and Chemical Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275, PR China.
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5
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Abstract
Abstract
Background: Protein profiling with high-throughput sample preparation and MALDI-TOF MS analysis is a new potential tool for diagnosis of human diseases. However, analytical reproducibility is a significant challenge in MALDI protein profiling. This minireview summarizes studies of reproducibility of MALDI protein profiling and current approaches to improve its analytical performance.
Methods: The PubMed database was searched using combinations of the following search terms: MALDI, SELDI, reproducibility, variation, precision, peak intensity, quantification, peptide, biomarkers, and proteomics. Acceptance criteria were detailed reports on the reproducibility with MALDI protein profiling and studies describing efforts to improve the analytical performance with this technology.
Results: The reported intraexperiment CVs of the peak intensity vary highly between individual protein peaks, with the reported mean CV of the peak intensity varying among studies from 4% to 26%. There is additional interexperiment variation in peak intensity. Current approaches to improve the analytical performance of MALDI protein profiling include automated sample processing, extensive prefractionation strategies, immunocapture, prestructured target surfaces, standardized matrix (co)crystallization, improved MALDI-TOF MS instrument components, internal standard peptides, quality-control samples, replicate measurements, and algorithms for normalization and peak detection.
Conclusions: Further evaluation and optimization of MALDI-TOF MS is recommended before use in routine analysis.
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Affiliation(s)
- Jakob Albrethsen
- Glostrup Research Institute, Glostrup Hospital, Glostrup, Denmark.
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6
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Chen X, Dong Y, Fan L, Yang D. Fluorescence for the ultrasensitive detection of peptides with functionalized nano-ZnS. Anal Chim Acta 2007; 582:281-7. [DOI: 10.1016/j.aca.2006.09.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2006] [Revised: 08/26/2006] [Accepted: 09/14/2006] [Indexed: 11/25/2022]
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7
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Ciordia S, de Los Ríos V, Albar JP. Contributions of advanced proteomics technologies to cancer diagnosis. Clin Transl Oncol 2006; 8:566-80. [PMID: 16952845 DOI: 10.1007/s12094-006-0062-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The ability of Medicine to effectively treat and cure cancer is directly dependent on their capability to detect cancers at their earliest stages. The advent of proteomics has brought with it the hope of discovering novel biomarkers in the early phases of tumorigenesis that can be used to diagnose diseases, predict susceptibility, and monitor progression. This discipline incorporates technologies that can be applied to complex biosystems such as serum and tissue in order to characterize the content of, and changes in, the proteome induced by physiological changes, benign or pathologic. These tools include 2-DE, 2D-DIGE, ICAT, protein arrays, MudPIT and mass spectrometries including SELDI-TOF. The application of these tools has assisted to uncover molecular mechanisms associated with cancer at the global level and may lead to new diagnostic tests and improvements in therapeutics. In this review these approaches are evaluated in the context of their contribution to cancer biomarker discovery. Particular attention is paid to the promising contribution of the ProteinChip/SELDI-TOF platform as a revolutionary approach in proteomic patterns analysis that can be applied at the bedside for discovering protein profiles that distinguish disease and disease-free states with high sensitivity and specificity. Understanding the basic concepts and tools used will illustrate how best to apply these technologies for patient benefit for the early cancer detection and improved patient care.
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Affiliation(s)
- Sergio Ciordia
- Proteomics Facility, Centro Nacional de Biotecnología-CSIC, Universidad Autónoma, Madrid, Spain
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8
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Zhu Y, Valdes R, Jortani SA. Application of bioaffinity mass spectrometry for analysis of ligands. Ther Drug Monit 2006; 27:694-9. [PMID: 16404796 DOI: 10.1097/01.ftd.0000179851.32093.dc] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Bioaffinity mass spectrometry is a novel technology for analysis of binding proteins and their ligands. In this review, we introduce the concepts and principles of bioaffinity surface-enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF MS). Various preactivated chip types and several approaches for binding of ligands or their binders to the chips are discussed. We also provide specific examples for the use of this technology for screening antibodies, analyzing ligands, glycoconjugates, protein-protein inter-actions, and DNA (RNA) binding proteins. In pursuit of developing new tests or studies of mechanism of drug action in therapeutic drug monitoring practice, this technology may provide a more rapid approach for ligand-binder studies.
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Affiliation(s)
- Yusheng Zhu
- Department of Pathology and Laboratory Medicine, University of Louisville School of Medicine, KY 40202, USA
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9
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Liu T, Toriyabe Y, Berkman CE. Purification of prostate-specific membrane antigen using conformational epitope-specific antibody-affinity chromatography. Protein Expr Purif 2006; 49:251-5. [PMID: 16815035 DOI: 10.1016/j.pep.2006.05.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 04/30/2006] [Accepted: 05/13/2006] [Indexed: 11/20/2022]
Abstract
Prostate-specific membrane antigen (PSMA) is a type II membrane protein that has attracted significant attention as a target for immunioscintigraphic and radioimmunotherapeutic applications for prostate cancer. However, definitive studies on its substrate and inhibitor specificity as well as protein-protein interactions have been somewhat limited by difficulties in the purification of native PSMA. In this study, we optimized the purification of native PSMA from LNCaP cells using conformational epitope-specific antibody-affinity chromatography. Western blot analysis and an HPLC-based enzymatic activity assay were used to compare the yield and activity of PSMA purified by different methods. The ratio of purified PSMA in a native and active conformation was determined by quantifying the amount of non-native PSMA not retained in a second antibody-affinity isolation. The addition of both a neutralization step and the inclusion of Zn(2+) to the equilibration buffer in desalting step provides considerable enhancement in the yield of active PSMA from LNCaP cells.
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Affiliation(s)
- Tiancheng Liu
- Department of Chemistry and Biochemistry, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132, USA
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10
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Yoshizaki T, Enomoto T, Nakashima R, Ueda Y, Kanao H, Yoshino K, Fukumoto M, Yoneda Y, Buzard GS, Murata Y. Altered protein expression in endometrial carcinogenesis. Cancer Lett 2005; 226:101-6. [PMID: 16039949 DOI: 10.1016/j.canlet.2004.11.053] [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] [Received: 11/11/2004] [Revised: 11/24/2004] [Accepted: 11/30/2004] [Indexed: 11/19/2022]
Abstract
We have discovered several protein biomarkers that are altered during carcinogenesis of the human uterine endometrium. Proteins prepared from 19 endometrial carcinomas (Group A), and 20 normal endometria obtained from benign gynecological conditions (Group B), were investigated by Surface Enhanced Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (SELDI-TOF-MS). Two proteins, EC1 and EC2, were consistently expressed differentially. EC1 had an increased level of expression in carcinomas (P<0.001), while EC2 was expressed at a lower level (P=0.004). The isoelectric points of EC1 and EC2 were approximately pH 5.0 and 7.0, respectively. These proteins are thus potential biomarkers for detection of endometrial carcinoma.
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Affiliation(s)
- Tatsuo Yoshizaki
- Department of Obstetrics and Gynecology, Faculty of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan
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11
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Le L, Chi K, Tyldesley S, Flibotte S, Diamond DL, Kuzyk MA, Sadar MD. Identification of serum amyloid A as a biomarker to distinguish prostate cancer patients with bone lesions. Clin Chem 2005; 51:695-707. [PMID: 15695329 DOI: 10.1373/clinchem.2004.041087] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Prostate cancer has a propensity to metastasize to the bone. Currently, there are no curative treatments for this stage of the disease. Sensitive biomarkers that can be monitored in the blood to indicate the presence or development of bone metastases and/or response to therapies are lacking. Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) is an affinity-based approach that allows sensitive and high-throughput protein profiling and screening of biological samples. METHODS We used SELDI-TOF MS for protein profiling of sera from prostate cancer patients (n = 38) with and without bone metastases in our effort to identify individual or multiple serum markers that may be of added benefit to those in current use. Serum was applied to ProteinChip surfaces (H4 and IMAC) to quickly screen samples and detect peaks predominating in the samples obtained from patients with bone metastases. Unique proteins in the bone metastasis cohort observed by SELDI-TOF MS were identified by two-dimensional gel electrophoresis, in-gel trypsin digestion, and tandem MS. The identities of the proteins were confirmed by ELISA and immunodepletion assays. RESULTS The cluster of unique proteins in the sera of patients with bone metastases was identified as isoforms of serum amyloid A. Machine-learning algorithms were also used to identify patients with bone metastases with a sensitivity and specificity of 89.5%. CONCLUSIONS SELDI-TOF MS protein profiling in combination with other proteomic approaches may provide diagnostic tools with potential clinical applications and serve as tools to aid in the discovery of biomarkers associated with various diseases.
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Affiliation(s)
- Lyly Le
- British Columbia Cancer Agency, Vancouver, British Columbia, Canada
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12
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Xiao Z, Prieto D, Conrads TP, Veenstra TD, Issaq HJ. Proteomic patterns: their potential for disease diagnosis. Mol Cell Endocrinol 2005; 230:95-106. [PMID: 15664456 DOI: 10.1016/j.mce.2004.10.010] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Revised: 10/06/2004] [Accepted: 10/14/2004] [Indexed: 10/26/2022]
Abstract
Alterations in proteins abundance, structure, or function, act as useful indicators of pathological abnormalities prior to development of clinical symptoms and as such are often useful diagnostic and prognostic biomarkers. The underlying mechanism of diseases such as cancer are, however, quite complicated in that often multiple dysregulated proteins are involved. It is for this reason that recent hypotheses suggest that detection of panels of biomarkers may provide higher sensitivities and specificities for disease diagnosis than is afforded with single markers. Recently, a novel approach based on the analysis of protein patterns has emerged that may provide a more effective means to diagnose diseases, such as ovarian and prostate cancer. The method is based on the use of surface-enhanced laser desorption/ionization (SELDI) time-of-flight mass spectrometry (TOF-MS) to detect differentially captured proteins from clinical samples, such as serum and plasma. This analysis results in the detection of "proteomic" patterns that have been shown in recent investigations to distinguish diseased and unaffected subjects to varying degrees. This review will discuss the basics of SELDI protein chip technology and highlight its recent applications in disease biomarker discovery with emphasis on cancer diagnosis.
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Affiliation(s)
- Zhen Xiao
- Laboratory of Proteomics and Analytical Technologies, SAIC-Frederick Inc., National Cancer Institute at Frederick, P.O. Box B, Frederick, MD 21702, USA
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13
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Pritlove DC, Tan BK, de Wit NCJ, Vatish M. Emerging technologies for the identification of therapeutic targets for the management of pre-eclampsia. Expert Opin Ther Targets 2004; 8:507-14. [PMID: 15584857 DOI: 10.1517/14728222.8.6.507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Pre-eclampsia is a common and serious complication of pregnancy characterised by hypertension and proteinuria. Genetic and environmental factors influence the occurrence and progression of the disease. Emerging experimental systems and increasingly specific analytical methods for the study of differences between normal and pre-eclamptic placentae are close to identifying specific indicators of disease, which may allow early diagnosis and intervention and reveal targets against which therapeutic agents can be developed.
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14
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Zatloukalová E, Kucerová Z. Separation of cobalt binding proteins by immobilized metal affinity chromatography. J Chromatogr B Analyt Technol Biomed Life Sci 2004; 808:99-103. [PMID: 15236692 DOI: 10.1016/j.jchromb.2004.03.066] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cobalt binding proteins from mouse liver, which were expressed in response to CoCl2 poisoning, were separated using gel permeation chromatography and then immobilised metal ion affinity chromatography (IMAC) with immobilized cobalt ions. Conditions used in IMAC-Co2+ were optimised. The fractions eluted with 60 mM imidazole were analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Differences between the samples were also evaluated by a two-dimensional electrophoresis. Samples from the Co2+-treated mice provided higher number of electrophoretic spots than those from the untreated mice. Relative molecular masses of these proteins are appropriately 37,000; 32,000 and 26,000 and their isoelectric points (pI) are 6.5-7.5.
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Affiliation(s)
- Eva Zatloukalová
- 1st Faculty of Medicine, Institute of Pathophysiology, Charles University, U Nemocnice 5, 128 53 Prague 2, Czech Republic.
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15
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Stoll D, Bachmann J, Templin MF, Joos TO. Microarray technology: an increasing variety of screening tools for proteomic research. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/s1741-8372(04)02400-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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16
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Vlahou A, Laronga C, Wilson L, Gregory B, Fournier K, McGaughey D, Perry RR, Wright GL, Semmes OJ. A novel approach toward development of a rapid blood test for breast cancer. Clin Breast Cancer 2003. [PMID: 14499014 DOI: 10.1016/s1526-8209(11)70627-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mammography remains the diagnostic test of choice for breast cancer, but 20% of cancers still go undetected. Many serum biomarkers have been reported for breast cancer but none have proven to represent effective diagnostic strategies. ProteinChip mass spectrometry is an innovative technology that searches the proteome for differentially expressed proteins, allowing for the creation of a panel or profile of biomarkers. The objective of this study was to construct unique cancer-associated serum profiles that, combined with a classification algorithm, would enhance the detection of breast cancer Pretreatment serum samples from 134 female patients (45 with cancer, 42 with benign disease, 47 normal) were procured prospectively following institutional review board-approved protocols. Proteins were denatured, applied onto ProteinChip affinity surfaces, and subjected to surface enhanced laser desorption/ionization (SELDI) time-of-flight mass spectrometry. The SELDI output was analyzed using Biomarker Pattern Software to develop a classification tree based on group-specific protein profiles. The cross-validation analysis of cancer versus normal revealed sensitivity and specificity rates of 80% and 79%, and for cancer versus benign disease, 78% and 83%, respectively. When 2 different chip surfaces were combined the sensitivity and specificity increased to 90% and 93%, respectively. The sensitivity and specificity of this technique are comparable to those of mammography and, if confirmed in a larger study, this technique could provide the means toward development of a simple blood test to aid in the early detection of breast cancer. The combination of SELDI ProteinChip mass spectrometry and a classification- and regression-tree algorithm has the potential to use serum protein expression profiles for detection and diagnosis of breast cancer.
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Affiliation(s)
- Antonia Vlahou
- Department of Microbiology, and Virginia Prostate Center, Eastern Virginia Medical School, Norfolk, VA 23507, USA
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17
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18
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Krüger S, Schroers R, Rooney CM, Gahn B, Chen SY. Identification of a naturally processed HLA-DR-restricted T-helper epitope in Epstein-Barr virus nuclear antigen type 1. J Immunother 2003; 26:212-21. [PMID: 12806275 DOI: 10.1097/00002371-200305000-00005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Epstein-Barr virus nuclear antigen type 1 (EBNA1), the only viral protein that is unequivocally expressed in all Epstein-Barr virus (EBV)-associated malignant diseases, is essential for viral DNA replication and maintenance of the viral episome in infected cells. A glycine-alanine repeat domain inhibits antigen processing through the ubiquitin-proteasome pathway for presentation on human leukocyte antigen (HLA) class I molecules. EBNA1 is not protected from the HLA class II processing pathway, and CD4+ HLA class II-restricted T cells recognize the antigen. CD4+ T-helper (Th) cells play critical roles in initiating, regulating, and maintaining immune responses against viral infections and tumors, so that inclusion of EBNA1 as a target antigen may improve immunotherapy for EBV-associated cancers. In this study, the authors used the TEPITOPE software program to predict promiscuous class II epitope candidates. After several HLA-DR-restricted peptides were identified by in vitro analysis of the T-cell response to synthetic peptides, a T-cell clone was established that was specific for one of the peptides. Functional studies were performed with this clone. The CD4+ T helper cells specific for the HLA-DR15-restricted peptide EBNA1(482) (AEGLRALLARSHVER) recognized naturally processed EBNA1 protein. This epitope was presented by several HLA-DR alleles, including DR4, DR7, and DR11. The inclusion of the promiscuous, naturally processed EBNA1(482) epitope in vaccine constructs could enhance immune responses against EBV-positive cancers.
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Affiliation(s)
- Stefan Krüger
- Center for Cell and Gene Therapy, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
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Batorfi J, Ye B, Mok SC, Cseh I, Berkowitz RS, Fulop V. Protein profiling of complete mole and normal placenta using ProteinChip analysis on laser capture microdissected cells. Gynecol Oncol 2003; 88:424-8. [PMID: 12648597 DOI: 10.1016/s0090-8258(02)00167-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Surface-enhanced laser desorption/ionization mass spectrometry (SELDI-MS) is a novel method for biomarker discovery that can provide a rapid protein expression profile from a variety of biological samples. Since SELDI-MS requires a small amount of biological material, this technique is ideal for analyzing proteins isolated from microdissected tissue samples. The current study was undertaken to investigate potential differences in protein expression between normal and molar trophoblast procured by laser capture microdissection (LCM) utilizing SELDI ProteinChip array technology. Further knowledge of protein expression in complete mole may advance our understanding of the pathogenesis of gestational trophoblastic diseases. MATERIALS AND METHODS Laser capture microdissected trophoblast cells from nine fresh complete moles were analyzed and compared to the trophoblast cells from 10 fresh normal placentas of comparable gestational age, using SELDI ProteinChip to identify potential differences in protein expression. RESULTS Three metal binding polypeptides were identified with the estimated molecular weights of 11.3, 13.8, and 14.0 kDa, which appeared in significantly lower levels in complete mole as compared to normal trophoblast cells (P < 0.001, P < 0.03, and P < 0.01). DISCUSSION While further characterization of these protein peaks is important and necessary, our current work clearly demonstrates that the combined technology of SELDI and LCM is effective in distinguishing protein expression between normal placenta and complete mole. Further knowledge of protein expression in complete mole may advance our understanding of molecular mechanisms and improve management in gestational trophoblastic diseases.
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Affiliation(s)
- Jozsef Batorfi
- Department of Obstetrics and Gynecology, National Health Center, Budapest, Hungary
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20
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Abstract
Proteomics is a rapidly emerging set of key technologies that are being used to identify proteins and map their interactions in a cellular context. With the sequencing of the human genome, the scope of proteomics has shifted from protein identification and characterization to include protein structure, function and protein-protein interactions. Technologies used in proteomic research include two-dimensional gel electrophoresis, mass spectrometry, yeast two-hybrids screens, and computational prediction programs. While some of these technologies have been in use for a long time, they are currently being applied to study physiology and cellular processes in high-throughput formats. It is the high-throughput approach that defines and characterizes modern proteomics. In this review, we discuss the current status of these experimental and computational technologies relevant to the three major aspects of proteomics-characterization of proteomes, identification of proteins, and determination of protein function. We also briefly discuss the development of new proteomic technologies that are based on recent advances in analytical and biochemical techniques, engineering, microfabrication, and computational prowess. The integration of these advances with established technologies is invaluable for the drive toward a comprehensive understanding of protein structure and function in the cellular milieu.
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MESH Headings
- Electrophoresis, Gel, Two-Dimensional/instrumentation
- Electrophoresis, Gel, Two-Dimensional/methods
- Electrophoresis, Gel, Two-Dimensional/trends
- Gene Expression Profiling/instrumentation
- Gene Expression Profiling/methods
- Gene Expression Profiling/trends
- Protein Interaction Mapping/instrumentation
- Protein Interaction Mapping/methods
- Proteome/chemistry
- Proteome/genetics
- Proteome/physiology
- Sensitivity and Specificity
- Sequence Analysis, Protein/instrumentation
- Sequence Analysis, Protein/methods
- Sequence Analysis, Protein/trends
- Spectrometry, Mass, Electrospray Ionization/instrumentation
- Spectrometry, Mass, Electrospray Ionization/methods
- Spectrometry, Mass, Electrospray Ionization/trends
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/instrumentation
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/trends
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Affiliation(s)
- Martin L Yarmush
- Center for Engineering in Medicine/Surgical Services, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
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21
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Weinberger SR, Viner RI, Ho P. Tagless extraction-retentate chromatography: A new global protein digestion strategy for monitoring differential protein expression. Electrophoresis 2002; 23:3182-92. [PMID: 12298090 DOI: 10.1002/1522-2683(200209)23:18<3182::aid-elps3182>3.0.co;2-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A new global protein digestion and selective peptide extraction strategy for the purpose of monitoring differential protein expression, coined as tagless extraction-retentate chromatography, is introduced. Target protein populations are firstly digested under reduced and alkylated conditions, and resultant peptides selectively extracted via covalent attachment to methionine residues by bromoacetyl reactive groups tethered to the surface of glass beads packed in small reaction vessels. After conjugation, reactive beads are stringently washed to remove nonspecifically bound peptides and then later treated with beta-mercaptoethanol to release captured methionine peptides in their nascent state, without complicating affinity tags. Recovered methionine containing peptides are profiled using the surface-enhanced laser desorption/ionization (SELDI) retentate chromatography mass spectrometry (RCMS) method. Selected peptides are further studied employing ProteinChip tandem mass spectrometry (MS/MS) analysis to identify their parent proteins. This approach has been applied to an Escherichia coli lysate model system and has demonstrated facility in reducing global digest complexity, sensitivity to low protein expression levels, and significant quantitative capability. It is envisioned that tagless extraction-RCMS will evolve to be a valuable approach for both basic research and clinical proteomics endeavors.
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22
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Sloane AJ, Duff JL, Wilson NL, Gandhi PS, Hill CJ, Hopwood FG, Smith PE, Thomas ML, Cole RA, Packer NH, Breen EJ, Cooley PW, Wallace DB, Williams KL, Gooley AA. High throughput peptide mass fingerprinting and protein macroarray analysis using chemical printing strategies. Mol Cell Proteomics 2002; 1:490-9. [PMID: 12239277 DOI: 10.1074/mcp.m200020-mcp200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We describe a chemical printer that uses piezoelectric pulsing for rapid, accurate, and non-contact microdispensing of fluid for proteomic analysis of immobilized protein macroarrays. We demonstrate protein digestion and peptide mass fingerprinting analysis of human plasma and platelet proteins direct from a membrane surface subsequent to defined microdispensing of trypsin and matrix solutions, hence bypassing multiple liquid-handling steps. Detection of low abundance, alkaline proteins from whole human platelet extracts has been highlighted. Membrane immobilization of protein permits archiving of samples pre-/post-analysis and provides a means for subanalysis using multiple chemistries. This study highlights the ability to increase sequence coverage for protein identification using multiple enzymes and to characterize N-glycosylation modifications using a combination of PNGase F and trypsin. We also demonstrate microdispensing of multiple serum samples in a quantitative microenzyme-linked immunosorbent assay format to rapidly screen protein macroarrays for pathogen-derived antigens. We anticipate the chemical printer will be a major component of proteomic platforms for high throughput protein identification and characterization with widespread applications in biomedical and diagnostic discovery.
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Affiliation(s)
- Andrew J Sloane
- Proteome Systems Limited, 1/35-41 Waterloo Rd., North Ryde, Sydney, New South Wales 2113, Australia
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23
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Abstract
Abstract
Early detection is critical in cancer control and prevention. Biomarkers help in this process by providing valuable information about a the status of a cell at any given point in time. As a cell transforms from nondiseased to neoplastic, distinct changes occur that could be potentially detected through the identification of the appropriate biomarkers. Biomarker research has benefited from advances in technology such as proteomics. We discuss here ongoing research in this field, focusing on proteomic technologies. The advances in two-dimensional electrophoresis and mass spectrometry are discussed in light of their contribution to biomarker research. Chip-based techniques, such as surface-enhanced laser desorption, and ionization and emerging methods, such as tissue and antibody arrays, are also discussed. The development of bioinformatic tools that have and are being developed in parallel to proteomics is also addressed. This report brings into focus the efforts of the Early Detection Research Network at the National Cancer Institute in harnessing scientific expertise from leading institutions to identify and validate biomarkers for early detection and risk assessment.
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Affiliation(s)
- Pothur R Srinivas
- Division of Cancer Prevention, National Cancer Institute, Rockville, MD 20852
| | - Sudhir Srivastava
- Cancer Biomarkers Research Group, Division of Cancer Prevention, National Cancer Institute, 6130 Executive Blvd., Rm. EPN 330F, Rockville, MD 20852
| | - Sam Hanash
- Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI 48109
| | - George L Wright
- Department of Microbiology and Molecular Cell Biology and Virginia Prostate Center, Eastern Virginia Medical School, Norfolk, VA 23501
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24
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Verma M, Wright GL, Hanash SM, Gopal-Srivastava R, Srivastava S. Proteomic approaches within the NCI early detection research network for the discovery and identification of cancer biomarkers. Ann N Y Acad Sci 2001; 945:103-15. [PMID: 11708463 DOI: 10.1111/j.1749-6632.2001.tb03870.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the postgenome era, proteomics provides a powerful approach for the analysis of normal and transformed cell functions, for the identification of disease-specific targets, and for uncovering novel endpoints for the evaluation of chemoprevention agents and drug toxicity. Unfortunately, the genomic information that has greatly expounded the genetic basis of cancer does not allow an accurate prediction of what is actually occurring at the protein level within a given cell type at any given time. The gene expression program of a given cell is affected by numerous factors in the in vivo environment resulting from tissue complexity and organ system orchestration, with cells acting in concert with each other and responding to changes in their microenvironment. Repositories of genomic information can be considered master "inventory lists" of genes and their maps, which need to be supplemented with protein-derived information. The National Cancer Institute's Early Detection Research Network is employing proteomics, or "protein walking", in the discovery and evaluation of biomarkers for cancer detection and for the identification of high-risk subjects. Armed with microdissection techniques, including the use of Laser Capture Microdissection (LCM) to procure pure populations of cells directly from human tissue, the Network is facilitating the development of technologies that can overcome the problem of tissue heterogeneity and address the need to identify markers in easily accessible biological fluids. Proteomic approaches complement plasma-based assays of circulating DNA for cancer detection and risk assessment. LCM, coupled with downstream proteomics applications, such as two-dimensional polyacrylamide gel electrophoresis and SELDI (surface enhanced laser desorption ionization) separation followed by mass spectrometry (MS) analysis, may greatly facilitate the characterization and identification of protein expression changes that track normal and disease phenotypes. We highlight recent work from Network investigators to demonstrate the potential of proteomics to identify proteins present in cancer tissues and body fluids that are relevant for cancer screening.
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Affiliation(s)
- M Verma
- Cancer Biomarkers Research Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, Maryland, USA
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25
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Abstract
An emerging field for the analysis of biological systems is the study of the complete protein complement of the genome, the 'proteome'. There are several complementary tools available for proteome analysis including 2D protein electrophoresis and mass spectrometry. Emerging technologies for proteome analysis include spotted-array-based methods and microfluidic devices. Taken together, these technologies provide a wealth of information that is useful in discovery-based science. However, there are some key limitations of these approaches and new technology is required to be able to fully integrate proteomic information with information obtained about DNA sequence, mRNA profiles and metabolite concentrations into effective models of biological systems.
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Affiliation(s)
- K H Lee
- 120 Olin Hall, Chemical Engineering, Cornell University, Ithaca NY 14853-5201, USA.
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26
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Vlahou A, Schellhammer PF, Mendrinos S, Patel K, Kondylis FI, Gong L, Nasim S, Wright Jr. GL. Development of a novel proteomic approach for the detection of transitional cell carcinoma of the bladder in urine. THE AMERICAN JOURNAL OF PATHOLOGY 2001; 158:1491-502. [PMID: 11290567 PMCID: PMC1891900 DOI: 10.1016/s0002-9440(10)64100-4] [Citation(s) in RCA: 326] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Development of noninvasive methods for the diagnosis of transitional cell carcinoma (TCC) of the bladder remains a challenge. A ProteinChip technology (surface enhanced laser desorption/ionization time of flight mass spectrometry) has recently been developed to facilitate protein profiling of biological mixtures. This report describes an exploratory study of this technology as a TCC diagnostic tool. Ninety-four urine samples from patients with TCC, patients with other urogenital diseases, and healthy donors were analyzed. Multiple protein changes were reproducibly detected in the TCC group, including five potential novel TCC biomarkers and seven protein clusters (mass range, 3.3 to 133 kd). One of the TCC biomarkers (3.4 kd) was also detected in bladder cancer cells procured from bladder barbotage and was identified as defensin. The TCC detection rates provided by the individual markers ranged from 43 to 70% and specificities from 70 to 86%. Combination of the protein biomarkers and clusters, increased significantly the sensitivity for detecting TCC to 87% with a specificity of 66%. Interestingly, this combinatorial approach provided sensitivity of 78% for detecting low-grade TCC compared to only 33% of voided urine or bladder-washing cytology. Collectively these results support the potential of this proteomic approach for the development of a highly sensitive urinary TCC diagnostic test.
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Affiliation(s)
| | | | - Savvas Mendrinos
- Eastern Virginia Medical School, Norfolk; and the Virginia Prostate Center,§
| | - Keyur Patel
- Eastern Virginia Medical School, Norfolk; and the Virginia Prostate Center,§
| | | | | | - Suhail Nasim
- Eastern Virginia Medical School, Norfolk; and the Virginia Prostate Center,§
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27
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Fung ET, Thulasiraman V, Weinberger SR, Dalmasso EA. Protein biochips for differential profiling. Curr Opin Biotechnol 2001; 12:65-9. [PMID: 11167075 DOI: 10.1016/s0958-1669(00)00167-1] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Progress has been made in utilizing ProteinChip technology to profile and compare protein expression in normal and diseased states, particularly in the areas of cancer, infectious disease and toxicology. The past year has also seen the development of several novel chip types designed to analyze proteins in a fashion analogous to the array-based format of DNA microarrays. Some of these platforms may be used for differential profiling.
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Affiliation(s)
- E T Fung
- Ciphergen Biosystems, 6611 Dumbarton Circle, Fremont, CA 94555, USA.
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28
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Wang S, Diamond DL, Hass GM, Sokoloff R, Vessella RL. Identification of prostate specific membrane antigen (PSMA) as the target of monoclonal antibody 107-1A4 by proteinchip�; array, surface-enhanced laser desorption/ionization (seldi) technology. Int J Cancer 2001; 92:871-6. [PMID: 11351309 DOI: 10.1002/ijc.1272] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recently we described the generation of the prostate tissue-specific monoclonal antibody (MAb) 107-1A4, its expression pattern and preliminary targeting of human prostate cancer xenografts. In this report we demonstrate that the target antigen for MAb 107-1A4 is prostate-specific membrane antigen (PSMA) using immunoaffinity absorption followed by SDS-PAGE and mass spectrometric analysis of peptides produced by in-gel tryptic digestion. The identity of the antigen has been confirmed by Western blots using MAbs of known specificity. MAb 107-1A4 is not reactive on Western blots. The conformational epitope for 107-1A4 is on the extracellular domain of PSMA. In competition studies, the binding of MAb 107-1A4 to LNCaP cells is inhibited by itself but not by any other of several other anti-PSMA MAbs, suggesting that the epitope may be unique. These results suggest that 107-1A4 is reactive to a conformational epitope in the external domain of PSMA that is unique among the panel of anti-PSMA MAbs in this study. Furthermore this work demonstrates the ability of mass spectroscopy to elucidate antibody-ligand interaction.
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Affiliation(s)
- S Wang
- Department of Urology, University of Washington Medical Center, Seattle, WA, USA
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29
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Abstract
This article presents current trends and advances in protein biochip technologies that rely upon extraction and retention of target proteins from liquid media. Analytical strengths as well as technical challenges for these evolving platforms are presented with particular emphasis on selectivity, sensitivity, throughput and utility in the post-genome era. A general review of protein biochip technology is provided, which delineates approaches for protein biochip format and operation, as well as protein detection. A focused discussion of three protein biochip technologies, Biomolecular Interaction Analysis (Biacore, Uppsala, Sweden), Surface Enhanced Laser Desorption/Ionisation (SELDI) ProteinChip Arrays (Ciphergen Biosystems, Fremont, CA, USA) and Fluorescent Planar Wave Guide (Zeptosens, Witterswil, Switzerland), follows along with examples of relevant applications.
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Affiliation(s)
- S R Weinberger
- Ciphergen Biosystems, Inc., 6611 Dumbarton Circle, Fremont, CA 94555, USA.
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30
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Biochips. Nat Biotechnol 2000. [DOI: 10.1038/80082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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