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Zhang X, Du X. Creation of glycoprotein imprinted self-assembled monolayers with dynamic boronate recognition sites and imprinted cavities for selective glycoprotein recognition. SOFT MATTER 2020; 16:3039-3049. [PMID: 32129364 DOI: 10.1039/c9sm02313e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Glycoproteins are involved in the pathogenesis and development of many diseases and are used as biomarkers for disease diagnosis. It is highly desirable to develop highly sensitive and selective methods for the detection of glycoproteins without the use of antibodies. Imprinting of proteins represents one of the most challenging tasks. Glycoprotein imprinted self-assembled monolayers (SAMs) were created, for the first time, from an oligo(ethylene glycol) (OEG) terminated 1,2-dithiolane derivative linked through an alkyl chain incorporated with two amide groups (DHAP) and combined functional thiols of p-mercaptophenylboronic acid (PMBA) and p-aminothiophenol (PATP) in aqueous media, without the use of polymerization initiators. Combined action of PMBA and PATP was essential for the development of boronate recognition sites for glycoproteins at the physiological pH, attributed to the water molecule-mediated Lewis acid-base interactions between the electron-deficient PMBA and the electron-rich PATP. DHAP played key roles not only in cementation of imprinted cavities by means of double hydrogen bond networks through the amide groups but also in resistance to nonspecific protein binding by terminal OEG moieties, as well as hydrogen bond binding sites from the amide groups exposed to imprinted cavities. The created glycoprotein imprinted SAMs showed excellent recognition selectivity of target glycoproteins. The strategy for tailor-made glycoprotein imprinted SAMs explores a new avenue to the creation of intelligent biomaterials and fabrication of chemosensors.
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Affiliation(s)
- Xianfeng Zhang
- Key Laboratory of Mesoscopic Chemistry (Ministry of Education), State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Chemistry for Life Sciences, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China.
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2
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Current advances and future visions on bioelectronic immunosensing for prostate-specific antigen. Biosens Bioelectron 2017; 98:267-284. [DOI: 10.1016/j.bios.2017.06.049] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 06/13/2017] [Accepted: 06/25/2017] [Indexed: 01/28/2023]
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Stephenson-Brown A, Acton AL, Preece JA, Fossey JS, Mendes PM. Selective glycoprotein detection through covalent templating and allosteric click-imprinting. Chem Sci 2015; 6:5114-5119. [PMID: 29142730 PMCID: PMC5666680 DOI: 10.1039/c5sc02031j] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Accepted: 06/15/2015] [Indexed: 01/05/2023] Open
Abstract
A hierarchical bottom-up route exploiting reversible covalent interactions with boronic acids and so-called click chemistry for selective glycoprotein detection is described. The self-assembled and imprinted surfaces confer high binding affinities, nanomolar sensitivity, exceptional glycoprotein specificity and selectivity.
Many glycoproteins are intimately linked to the onset and progression of numerous heritable or acquired diseases of humans, including cancer. Indeed the recognition of specific glycoproteins remains a significant challenge in analytical method and diagnostic development. Herein, a hierarchical bottom-up route exploiting reversible covalent interactions with boronic acids and so-called click chemistry for the fabrication of glycoprotein selective surfaces that surmount current antibody constraints is described. The self-assembled and imprinted surfaces, containing specific glycoprotein molecular recognition nanocavities, confer high binding affinities, nanomolar sensitivity, exceptional glycoprotein specificity and selectivity with as high as 30 fold selectivity for prostate specific antigen (PSA) over other glycoproteins. This synthetic, robust and highly selective recognition platform can be used in complex biological media and be recycled multiple times with no performance decrement.
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Affiliation(s)
- Alexander Stephenson-Brown
- School of Chemical Engineering , University of Birmingham , Edgbaston , Birmingham , West Midlands B15 2TT , UK .
| | - Aaron L Acton
- School of Chemical Engineering , University of Birmingham , Edgbaston , Birmingham , West Midlands B15 2TT , UK .
| | - Jon A Preece
- School of Chemistry , University of Birmingham , Edgbaston , Birmingham , West Midlands B15 2TT , UK .
| | - John S Fossey
- School of Chemistry , University of Birmingham , Edgbaston , Birmingham , West Midlands B15 2TT , UK .
| | - Paula M Mendes
- School of Chemical Engineering , University of Birmingham , Edgbaston , Birmingham , West Midlands B15 2TT , UK .
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Svobodova M, Bunka DHJ, Nadal P, Stockley PG, O'Sullivan CK. Selection of 2'F-modified RNA aptamers against prostate-specific antigen and their evaluation for diagnostic and therapeutic applications. Anal Bioanal Chem 2013; 405:9149-57. [PMID: 24043377 DOI: 10.1007/s00216-013-7350-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 08/30/2013] [Accepted: 09/05/2013] [Indexed: 12/11/2022]
Abstract
Currently, prostate-specific antigen (PSA) is considered to be the most sensitive marker available for prostate cancer detection and for monitoring of disease progression. In addition to its importance as a tumor marker, PSA has a role in the biological activity of cancer growth and proliferation. Therefore, the inhibition or activation of its biological activity may be used in prostate cancer therapy. Here, we describe the isolation and characterization of new 2'F-modified RNA aptamers directed against PSA. Binding studies demonstrate the ability of these new aptamers to specifically recognize their target with dissociation constants in the nanomolar range. In order to demonstrate the functionality of the selected aptamers, an apta-PCR approach was used for the quantitative detection of PSA, achieving a limit of detection of 11 nM. Furthermore, the potential use of the selected aptamers in therapeutics was demonstrated with the 2'F-modified aptamers being highly stable in human serum and having the ability to moderate the activity of PSA, which will be explored for the treatment of prostate cancer.
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Affiliation(s)
- M Svobodova
- Nanobiotechnology and Bioanalysis group, Department of Chemical Engineering, Universitat Rovira i Virgili, 43007, Tarragona, Spain,
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Baumgart Y, Otto A, Schäfer A, Usbeck E, Cott C, Schott A, Tornack M, Wenzel A, Mossie A, Birkenmeier G. Characterization of Novel Monoclonal Antibodies for Prostate-Specific Antigen (PSA) with Potency to Recognize PSA Bound to α2-Macroglobulin. Clin Chem 2005; 51:84-92. [PMID: 15528296 DOI: 10.1373/clinchem.2004.039636] [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: 11/06/2022]
Abstract
AbstractBackground: Different molecular forms of prostate-specific antigen (PSA) have been used to differentiate between benign prostatic hyperplasia and prostate cancer. Detecting PSA bound to endogenous inhibitors such as α1-antichymotrypsin (ACT) and α2-macroglobulin (α2M) is often difficult because of epitope masking or sensitivity problems. Here we report the characterization of four novel mouse monoclonal antibodies (mabs) obtained by immunization with PSA-α2M complexes. Their ability to detect free PSA and PSA-inhibitor complexes was shown, and their epitopes were analyzed by phage display technology.Methods: The properties of the mabs were studied by competition and sandwich assays and by Western blotting. Epitope mapping was performed by screening of a phage display peptide library.Results: All four mabs recognized free PSA, PSA-ACT, and PSA-α2M complexes, but to various degrees. With different combinations of mabs in competition experiments, antibodies were identified that enhance binding of other mabs to PSA, forming the molecular basis of a very sensitive assay for the detection of PSA and PSA-ACT complexes. Mabs with highest reactivity for PSA-α2M were selected to establish an immunoassay for that complex. Western blot analysis revealed that all mabs recognized conformational epitopes of PSA. These findings were supported by phage display results demonstrating mimotopes in the PSA molecule.Conclusion: The results presented here could aid in the further development of clinically relevant assays for PSA and PSA-α2M complexes.
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Affiliation(s)
- Yvonne Baumgart
- Institute of Biochemistry, University of Leipzig, Liebigstrasse 16, 04103 Leipzig, Germany
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6
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Wan XS, Xu YA, Ware JH, Kennedy AR. Three immunoassays based on monoclonal antibodies specific for prostate specific antigen (PSA), alpha-1-antichymotrypsin (ACT), and the PSA-ACT complex. Prostate 2003; 56:131-41. [PMID: 12746838 DOI: 10.1002/pros.10247] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Prostate specific antigen (PSA) has been widely used as a biomarker for the screening and diagnosis of prostate cancer. PSA in serum predominantly exists as a complex with alpha-1-antichymotrypsin (ACT), and measurement of free PSA and the PSA-ACT complex may improve the utility of the serum PSA assay for differential diagnosis of prostate cancer and non-malignant prostate diseases, such as benign prostatic hyperplasia (BPH). METHODS Monoclonal antibodies (MAbs) against PSA, ACT, and the PSA-ACT complex were produced by immunizing mice with an incubated mixture of PSA and ACT, and characterized by Western blot analyses and several enzyme-linked immunosorbant assay (ELISA) methods. RESULTS The MAbs produced in this study are capable of distinguishing the PSA-ACT complex from free PSA and ACT. Four MAbs have been selected and utilized to construct three ELISA systems for the separate measurements of free PSA, the PSA-ACT complex, and total PSA. CONCLUSIONS The three PSA assay systems developed in this study can specifically measure free PSA, total PSA, and the PSA-ACT complex with equal molar sensitivity. It is expected that these PSA assay systems could be useful in the diagnosis of prostate cancer.
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Affiliation(s)
- X Steven Wan
- Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104--6072, USA.
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Sarkar P, Pal PS, Ghosh D, Setford SJ, Tothill IE. Amperometric biosensors for detection of the prostate cancer marker (PSA). Int J Pharm 2002; 238:1-9. [PMID: 11996805 DOI: 10.1016/s0378-5173(02)00015-7] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Prostate specific antigen (PSA) has been identified as the most reliable clinical tool for diagnosing and monitoring prostate cancer (CAP). Since, there is no curative therapy available for prostate cancer, detecting the disease at the early stage is the best hope of increasing mortality rate. There are some procedures available for the detection of prostate cancer e.g. Tandem-R PSA, Hybritech Inc. (USA), IMx-PSA Abbott Laboratories (USA). However, these are time consuming and costly. We have developed a very simple and cost effective technique for identification and monitoring of prostate cancer using amperometric immunosensor. PSA is a glycoprotein with 93% peptide and 7% sugar content and isoelectric pH of 6.9. It may exist in the human serum as free (f-PSA) and complex (PSA-ACT) forms. Normally if the total PSA (t-PSA) level is more than 10 ng/ml, CAP is suspected. This paper presents an amperometric detection procedure for t-PSA using three electrode system in which working electrode (WE) is made of hydroxyethyl cellulose (HEC) and rhodinised carbon. The method used is rapid, very easy to use and involves low cost compared with other procedures. The electrochemical response was directly observed due to enzymatic reaction via a sandwich immunoassay on the WE. Monoclonal capture antibody (Mab) to PSA was immobilised on the WE and the other Mab labelled by the enzyme marker, horseradish peroxidase (HRP), was used as a tracer antibody.
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Affiliation(s)
- Priyabrata Sarkar
- Department of Polymer Science and Technology, University of Calcutta, 92 A.P.C. Road, Calcutta 700009, India.
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Corey MJ, Kinders RJ, Poduje CM, Bruce CL, Rowley H, Brown LG, Hass GM, Vessella RL. Mechanistic studies of the effects of anti-factor H antibodies on complement-mediated lysis. J Biol Chem 2000; 275:12917-25. [PMID: 10777591 DOI: 10.1074/jbc.275.17.12917] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have recently reported that complement factor H, a negative regulator of complement-mediated cytotoxicity, is produced and secreted by most bladder cancers. This observation was exploited in the development of the BTA stat and BTA TRAK diagnostic assays, both of which make use of two factor H-specific monoclonal antibodies in sandwich format. Here we show that both antibodies exert interesting effects on the biochemistry of complement activation in in vitro systems. Antibody X13.2 competes with C3b for association with factor H and strongly inhibits factor H/factor I-mediated cleavage of C3b, thereby evidently inactivating a negative regulator of complement; yet, the antibody strongly inhibits complement-mediated lysis as well. Conversely, antibody X52. 1, which does not compete with C3b and has no effect on solution-phase cleavage of C3b, is capable of enhancing complement-mediated lysis of various cell types, including cancer cells, by over 10-fold. Our observations indicate that it is possible to deconvolute the biochemical roles of factor H in complement by means of appropriate inhibitors, a finding with potentially valuable implications for both basic research and cancer therapy.
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Affiliation(s)
- M J Corey
- Bion Diagnostic Sciences, Redmond, Washington 98052, USA.
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Blijenberg BG, Storm BN, Van Zelst BD, Kruger AE, Schröder FH. New developments in the standardization of total prostate-specific antigen. Clin Biochem 1999; 32:627-34. [PMID: 10638945 DOI: 10.1016/s0009-9120(99)00074-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Analytical evaluation of the calibration of three recently launched assays for the measurement of total prostate-specific antigen, i.e., IMx Total PSA (Abbott), Elecsys PSA (Roche), and IMMULITE 3rd Generation PSA (DPC). DESIGN AND METHODS For accuracy assessment two reference materials were applied namely, Stanford 90:10 PSA Calibrator and Certified Reference Material 613 Prostate-Specific Antigen. Dilutions of these preparations were analyzed with all assays. In addition, clinical specimens from known prostate cancer or benign prostate hyperplasia patients and samples taken from an ongoing prostate cancer screening study were used for comparison. RESULTS Application of the Stanford Calibrator revealed results well within 10% of the calculated values for all assays. Regarding the CRM Calibrator only the IMx Total PSA proved to approach the line of identity. The IMMULITE results differed about 40% and the Elecsys about 18% from the calculated values. The comparison with clinical specimens showed statistically different results for the combination IMMULITE-IMx and for IMMULITE-Elecsys. The regression lines for both collections were: y(IMx) = 0.86x(IMMULITE) +0.12 (n = 104, r = 0.970, Sy/x = 0.883 microg/L) and y(Elecsys) = 0.98x(IMMULITE) +0.38 (n = 97, r = 0.976, Sy/x = 0.733 microg/L). In the lower measuring range (PSA <5.0 microg/L) as measured with the screening samples (n = 43), these differences were less pronounced. CONCLUSION In analytical sense a difference was found for both reference preparations in the assays studied. Clinically, despite improvements in methodology, results for total prostate-specific antigen are still not interchangeable. The possible consequences need to be elaborated.
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Affiliation(s)
- B G Blijenberg
- Department of Clinical Chemistry, University Hospital Rotterdam, The Netherlands.
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Blijenberg BG, Storm BN, Kruger AE, Schröder FH. On the standardization of total prostate-specific antigen: an exercise with two reference preparations. Clin Chem Lab Med 1999; 37:545-52. [PMID: 10418746 DOI: 10.1515/cclm.1999.088] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In this study, 112 serum samples were analyzed for total prostate-specific antigen with three well-established assays i.e. Tandem R and Tandem E (both from Hybritech Inc., San Diego, USA) and Prostatus Free/Total from Wallac Oy, Turku, Finland. Thirty-two samples were collected from prostate cancer patients, 32 from patients with benign prostate hyperplasia and 48 from men participating in a screening study for prostate cancer. The aim of the study was to compare the results before and after recalculation with the data obtained with two reference preparations for total prostate-specific antigen: Stanford 90:10 PSA Calibrator and Certified Reference Material 613 Prostate-Specific Antigen. Comparing the actual results revealed almost perfect correlations between Tandem R and Tandem E and between both Tandem assays and Prostatus. We observed statistically significant differences in accuracy between Tandem R and Tandem E: y(Tandem E)= 1.05 x(Tandem R)+0.07 and between Tandem E and Prostatus: y(Prostatus)= 0.94 x(Tandem E)+0.02 In both comparisons prostate-specific antigen values ranged from 0-40 microg/l. Recalculation with both reference preparations did not solve these discrepancies. One exception was the combination Tandem R and Tandem E. The application of either reference preparation solved the differences in accuracy here. In conclusion, even after recalibration, assays for total prostate-specific antigen are still not completely interchangeable.
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Affiliation(s)
- B G Blijenberg
- Department of Clinical Chemistry, University Hospital Rotterdam, The Netherlands.
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Michel S, Deléage G, Charrier JP, Passagot J, Battail-Poirot N, Sibai G, Jolivet M, Jolivet-Reynaud C. Anti-Free Prostate-specific Antigen Monoclonal Antibody Epitopes Defined by Mimotopes and Molecular Modeling. Clin Chem 1999. [DOI: 10.1093/clinchem/45.5.638] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
AbstractBackground: Prostate-specific antigen (PSA) is an important marker for the diagnosis and management of prostate cancer, and the free PSA/total PSA ratio has been shown to be efficient for distinguishing prostate cancer from benign prostatic hyperplasia. We report here the characterization of seven mouse monoclonal antibodies (mAbs) and the partial localization of two conformational epitopes identified by anti-free PSA mAbs.Methods: The mAbs were studied by competition and sandwich assays, and the epitope localization of the two anti-free PSA mAbs (6C8D8 and 5D3D11) was performed using phage displayed peptide libraries and molecular modeling.Results: The seven mAbs were classified into three groups according to their recognition specificities and their ability to inhibit the enzymatic activity of PSA and the formation of PSA-α1-antichymotrypsin (ACT) complex. Among the anti-free PSA mAb group, 6C8D8 recognized the phage displayed peptide RKLRPHWLHFHPVAV, two parts of which presented similarities with two regions distant on the PSA sequence but joined in the tridimensional structure. mAb 5D3D11 recognized the peptide DTPYPWGWLLDEGYD, which is similar to a PSA region located on the board of the groove containing the PSA enzymatic site. Both epitopes were located in the theoretical ACT binding site described previously. Moreover, these mAbs were able to inhibit the enzymatic activity of PSA.Conclusions: These epitope localizations are in agreement with the ability of both mAbs to inhibit enzymatic activity and ACT fixation. The results presented here could bring information for the generation of clinically relevant PSA assays.
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Affiliation(s)
- Sandrine Michel
- bioMérieux, Département R&D unité Immunoessais, Chemin de l’Orme, 69280 Marcy L’Etoile, France
| | - Gilbert Deléage
- Institut de Biologie et de Chimie des Proteines, Unite Propre de Recherche, 412/Centre National de la Recherche Scientifique, 7 passage du Vercors, 69367 Lyon Cedex 07, France
| | - Jean-Philippe Charrier
- bioMérieux, Département R&D unité Immunoessais, Chemin de l’Orme, 69280 Marcy L’Etoile, France
| | - Jacques Passagot
- bioMérieux, Département R&D unité Immunoessais, Chemin de l’Orme, 69280 Marcy L’Etoile, France
| | - Nicole Battail-Poirot
- bioMérieux, Département R&D unité Immunoessais, Chemin de l’Orme, 69280 Marcy L’Etoile, France
| | - Geneviève Sibai
- bioMérieux, Département R&D unité Immunoessais, Chemin de l’Orme, 69280 Marcy L’Etoile, France
| | - Michel Jolivet
- bioMérieux, Département R&D unité Immunoessais, Chemin de l’Orme, 69280 Marcy L’Etoile, France
| | - Colette Jolivet-Reynaud
- Unite Mixte de Recherche, 103 bioMérieux/Centre National de la Recherche Scientifique, ENS, 46 allée d’Italie, 69364 Lyon Cedex 07, France
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Rittenhouse HG, Finlay JA, Mikolajczyk SD, Partin AW. Human Kallikrein 2 (hK2) and prostate-specific antigen (PSA): two closely related, but distinct, kallikreins in the prostate. Crit Rev Clin Lab Sci 1998; 35:275-368. [PMID: 9759557 DOI: 10.1080/10408369891234219] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Recent studies on human kallikrein 2 (hK2) have revealed striking similarities and significant differences with the closely related kallikrein PSA. Both PSA and hK2 are primarily localized to the prostate and share close structural similarities. Although both kallikreins are produced by the same secretory epithelial cells in the prostate, hK2 is associated more with prostate tumors than PSA and is highly expressed in poorly differentiated cancer cells. The potent trypsin-like activity of hK2 contrasts with the weak chymotrypsin-like activity of PSA. The inactive precursor form of PSA, proPSA, is converted rapidly to active PSA by hK2, suggesting an important in vivo regulatory function by hK2 on PSA activity. The high homology between hK2 and PSA results in significant cross-reactivity to hK2 by polyclonal and some monoclonal antibodies to PSA. Future studies on both PSA and hK2 need to take into account this potential for cross-reactivity. Specific monoclonal antibodies to hK2 have now demonstrated that serum levels of hK2, like PSA, are correlated with prostate cancer. The production of hK2 protein in active protease form and specific monoclonal antibodies to the hK2 antigen will allow extensive future studies delineating the physiological and clinical utility of this new prostate antigen.
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Affiliation(s)
- H G Rittenhouse
- Research and Development Department, Hybritech Incorporated, Beckman Coulter, Inc., San Diego, California, USA.
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Abstract
BACKGROUND Our objective was to evaluate five preclinical prostate cancer (CaP) xenograft models to determine whether (1) prostate-specific antigen (PSA) formed complexes in murine serum, (2) the percentage of free PSA (f-PSA) was characteristic of a given xenograft line, and (3) the percentage of f-PSA was similar to that in the patient at time of tumor harvest. Our fourth objective was to identify which murine serpin(s) bind(s) to PSA in vivo. METHODS Xenografts were established from metastatic foci. The percentage of f-PSA, and total PSA (t-PSA) in serum of animals bearing CaP xenografts was determined by immunoassay. Size exclusion high-performance liquid chromatography and Western blots were used to evaluate the presence of PSA complexes in murine serum. Edman degradation was used to determine the N-terminal sequence of complexed proteins. RESULTS PSA was detected as both free and complexed forms in murine serum from all mice bearing the CaP xenografts. Three xenografts (related sublines) produced PSA that resulted in low mean percentages of f-PSA (1.9-6.4%). In sera from the other two xenografts, the mean percentages of f-PSA were high (>25%); patient sera, where available at time of tumor acquisition, were in agreement. Western blots showed that murine protease inhibitors formed complexes with PSA. Edman degradation yielded a sequence with 80% homology over 15 amino acids with that of murine alpha1-protease inhibitor (alpha1-PI). CONCLUSIONS Our data have shown that the majority of PSA secreted by these CaP xenografts complexes in murine serum with a protease inhibitor with high homology to murine alpha1-PI and that the percentage of f-PSA is a characteristic of each xenograft line tested, which is in agreement with patient values at time of tumor harvest. These CaP xenografts offer opportunities for study of human PSA biology and phenomenology.
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Affiliation(s)
- K R Buhler
- Department of Urology, School of Medicine, University of Washington, Seattle 98195, USA.
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14
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Abstract
BACKGROUND Our objective was to investigate the presence of prostate specific antigen (PSA) and alpha-1-antichymotrypsin (ACT) mRNA and protein in prostate cancer cell lines, and the complexing characteristics of expressed PSA. METHODS RT-PCR, immunohistochemistry, and Western blots were employed. Trypsin treatment of PSA was performed to establish the possible presence of an activatable form of PSA. RESULTS ACT mRNA and protein were detected in LNCaP, PC-3, and DU 145 by RT-PCR and by immunohistochemistry, respectively. Only LNCaP cells were positive for PSA mRNA and protein. LNCaP expressed approximately 30% active PSA, approximately 40% putative zymogen form of PSA, and approximately 30% stably inactive PSA. CONCLUSIONS We have shown that the majority of PSA expressed by LNCaP cells is present in free, noncomplexed forms in the conditioned media. A portion (40%) can be activated by trypsin, while the rest is stably inactive PSA. LNCaP cells may serve as a source of the "unreactive" PSA present in prostate cancer patients' serum.
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Affiliation(s)
- E Corey
- Department of Urology, School of Medicine, University of Washington, Seattle 98195, USA.
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15
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Corey E, Buhler KR, Vessella RL. Cross-reactivity of ten anti-prostate-specific antigen monoclonal antibodies with human glandular kallikrein. Urology 1997; 50:567-71; discussion 571-2. [PMID: 9338733 DOI: 10.1016/s0090-4295(97)00415-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES Prostate-specific antigen (PSA) is commonly used as a marker for prostate disease. Prostate epithelium expresses both PSA and human glandular kallikrein (hK2) proteins, which share 80% sequence homology. The immunologic cross-reactivity of these two proteins could potentially interfere with determination of PSA levels in diagnoses of prostate cancer. We set out to determine the extent of this cross-reactivity for a panel of 10 anti-PSA monoclonal antibodies (mAbs). METHODS Enzyme-linked immunosorbent assay (ELISA), sandwich assays, and western transfer techniques were used to assess the PSA/hK2 cross-reactivity of the anti-PSA mAbs. RESULTS We did not detect the hK2 protein with any of the 10 anti-PSA mAbs under western transfer conditions. In ELISA experiments, 8 of 10 mAbs exhibited hK2 cross-reactivity under certain conditions. However, no combination of mAbs tested in sandwich assays exhibited a signal in hK2 cross-reactivity experiments greater than 0.1% of the PSA signal. CONCLUSIONS We have evaluated 10 anti-PSA mAbs and determined that despite the 80% homology between PSA and hK2 proteins, cross-reactivity with hK2 by these antibodies would not significantly affect the determination of PSA levels by means of sandwich assays.
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Affiliation(s)
- E Corey
- Tumor Immunology Laboratory of the Urology Department, Medical School, University of Washington, Seattle 98195, USA
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