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Kumar AA, Vine KL, Ranson M. Recent Advances in Targeting the Urokinase Plasminogen Activator with Nanotherapeutics. Mol Pharm 2023. [PMID: 37119285 DOI: 10.1021/acs.molpharmaceut.3c00055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The aberrant proteolytic landscape of the tumor microenvironment is a key contributor of cancer progression. Overexpression of urokinase plasminogen activator (uPA) and/or its associated cell-surface receptor (uPAR) in tumor versus normal tissue is significantly associated with worse clinicopathological features and poorer patient survival across multiple cancer types. This is linked to mechanisms that facilitate tumor cell invasion and migration, via direct and downstream activation of various proteolytic processes that degrade the extracellular matrix─ultimately leading to metastasis. Targeting uPA has thus long been considered an attractive anticancer strategy. However, poor bioavailability of several uPA-selective small-molecule inhibitors has limited early clinical progress. Nanodelivery systems have emerged as an exciting method to enhance the pharmacokinetic (PK) profile of existing chemotherapeutics, allowing increased circulation time, improved bioavailability, and targeted delivery to tumor tissue. Combining uPA inhibitors with nanoparticle-based delivery systems thus offers a remarkable opportunity to overcome existing PK challenges associated with conventional uPA inhibitors, while leveraging potent candidates into novel targeted nanotherapeutics for an improved anticancer response in uPA positive tumors.
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Affiliation(s)
- Ashna A Kumar
- School of Chemistry and Molecular Biosciences, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Kara L Vine
- School of Chemistry and Molecular Biosciences, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Marie Ranson
- School of Chemistry and Molecular Biosciences, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
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2
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Kumar AA, Buckley BJ, Ranson M. The Urokinase Plasminogen Activation System in Pancreatic Cancer: Prospective Diagnostic and Therapeutic Targets. Biomolecules 2022; 12:152. [PMID: 35204653 PMCID: PMC8961517 DOI: 10.3390/biom12020152] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/13/2022] [Accepted: 01/16/2022] [Indexed: 02/07/2023] Open
Abstract
Pancreatic cancer is a highly aggressive malignancy that features high recurrence rates and the poorest prognosis of all solid cancers. The urokinase plasminogen activation system (uPAS) is strongly implicated in the pathophysiology and clinical outcomes of patients with pancreatic ductal adenocarcinoma (PDAC), which accounts for more than 90% of all pancreatic cancers. Overexpression of the urokinase-type plasminogen activator (uPA) or its cell surface receptor uPAR is a key step in the acquisition of a metastatic phenotype via multiple mechanisms, including the increased activation of cell surface localised plasminogen which generates the serine protease plasmin. This triggers multiple downstream processes that promote tumour cell migration and invasion. Increasing clinical evidence shows that the overexpression of uPA, uPAR, or of both is strongly associated with worse clinicopathological features and poor prognosis in PDAC patients. This review provides an overview of the current understanding of the uPAS in the pathogenesis and progression of pancreatic cancer, with a focus on PDAC, and summarises the substantial body of evidence that supports the role of uPAS components, including plasminogen receptors, in this disease. The review further outlines the clinical utility of uPAS components as prospective diagnostic and prognostic biomarkers for PDAC, as well as a rationale for the development of novel uPAS-targeted therapeutics.
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Affiliation(s)
- Ashna A. Kumar
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (A.A.K.); (B.J.B.)
- School of Chemistry and Molecular Biosciences, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Benjamin J. Buckley
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (A.A.K.); (B.J.B.)
- School of Chemistry and Molecular Biosciences, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Marie Ranson
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (A.A.K.); (B.J.B.)
- School of Chemistry and Molecular Biosciences, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
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3
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Urokinase plasminogen activator as an anti-metastasis target: inhibitor design principles, recent amiloride derivatives, and issues with human/mouse species selectivity. Biophys Rev 2022; 14:277-301. [PMID: 35340592 PMCID: PMC8921380 DOI: 10.1007/s12551-021-00921-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 11/18/2021] [Indexed: 01/09/2023] Open
Abstract
The urokinase plasminogen activator (uPA) is a widely studied anticancer drug target with multiple classes of inhibitors reported to date. Many of these inhibitors contain amidine or guanidine groups, while others lacking these groups show improved oral bioavailability. Most of the X-ray co-crystal structures of small molecule uPA inhibitors show a key salt bridge with the side chain carboxylate of Asp189 in the S1 pocket of uPA. This review summarises the different classes of uPA inhibitors, their binding interactions and experimentally measured inhibitory potencies and highlights species selectivity issues with attention to recently described 6-substituted amiloride and 5‑N,N-(hexamethylene)amiloride (HMA) derivatives.
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4
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S El Salamouni N, Buckley BJ, Jiang L, Huang M, Ranson M, Kelso MJ, Yu H. Disruption of Water Networks is the Cause of Human/Mouse Species Selectivity in Urokinase Plasminogen Activator (uPA) Inhibitors Derived from Hexamethylene Amiloride (HMA). J Med Chem 2021; 65:1933-1945. [PMID: 34898192 DOI: 10.1021/acs.jmedchem.1c01423] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The urokinase plasminogen activator (uPA) plays a critical role in tumor cell invasion and migration and is a promising antimetastasis target. 6-Substituted analogues of 5-N,N-(hexamethylene)amiloride (HMA) are potent and selective uPA inhibitors that lack the diuretic and antikaliuretic properties of the parent drug amiloride. However, the compounds display pronounced selectivity for human over mouse uPA, thus confounding interpretation of data from human xenograft mouse models of cancer. Here, computational and experimental findings reveal that residue 99 is a key contributor to the observed species selectivity, whereby enthalpically unfavorable expulsion of a water molecule by the 5-N,N-hexamethylene ring occurs when residue 99 is Tyr (as in mouse uPA). Analogue 7 lacking the 5-N,N-hexamethylene ring maintained similar water networks when bound to human and mouse uPA and displayed reduced selectivity, thus supporting this conclusion. The study will guide further optimization of dual-potent human/mouse uPA inhibitors from the amiloride class as antimetastasis drugs.
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Affiliation(s)
- Nehad S El Salamouni
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Benjamin J Buckley
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.,CONCERT-Translational Cancer Research Centre, Sydney, NSW 2750, Australia
| | - Longguang Jiang
- National Joint Biomedical Engineering Research Centre on Photodynamic Technologies, Fuzhou University, Fujian 350116, China
| | - Mingdong Huang
- National Joint Biomedical Engineering Research Centre on Photodynamic Technologies, Fuzhou University, Fujian 350116, China
| | - Marie Ranson
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.,CONCERT-Translational Cancer Research Centre, Sydney, NSW 2750, Australia
| | - Michael J Kelso
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Haibo Yu
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
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5
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Buckley BJ, Majed H, Aboelela A, Minaei E, Jiang L, Fildes K, Cheung CY, Johnson D, Bachovchin D, Cook GM, Huang M, Ranson M, Kelso MJ. 6-Substituted amiloride derivatives as inhibitors of the urokinase-type plasminogen activator for use in metastatic disease. Bioorg Med Chem Lett 2019; 29:126753. [PMID: 31679971 DOI: 10.1016/j.bmcl.2019.126753] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 11/25/2022]
Abstract
The oral K+-sparing diuretic amiloride shows anti-cancer side-activities in multiple rodent models. These effects appear to arise, at least in part, through moderate inhibition of the urokinase-type plasminogen activator (uPA, Ki = 2.4 µM), a pro-metastatic trypsin-like serine protease that is upregulated in many aggressive solid malignancies. In applying the selective optimization of side-activity (SOSA) approach, a focused library of twenty two 6-substituted amiloride derivatives were prepared, with multiple examples displaying uPA inhibitory potencies in the nM range. X-ray co-crystal structures revealed that the potency increases relative to amiloride arise from increased occupancy of uPA's S1β subsite by the appended 6-substituents. Leading compounds were shown to have high selectivity over related trypsin-like serine proteases and no diuretic or anti-kaliuretic effects in rats. Compound 15 showed anti-metastatic effects in a xenografted mouse model of late-stage lung metastasis.
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Affiliation(s)
- Benjamin J Buckley
- School of Chemistry and Molecular Bioscience, University of Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, NSW 2522, Australia; Molecular Horizons, University of Wollongong, NSW 2522, Australia
| | - Hiwa Majed
- School of Chemistry and Molecular Bioscience, University of Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, NSW 2522, Australia; Molecular Horizons, University of Wollongong, NSW 2522, Australia
| | - Ashraf Aboelela
- School of Chemistry and Molecular Bioscience, University of Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, NSW 2522, Australia; Molecular Horizons, University of Wollongong, NSW 2522, Australia
| | - Elahe Minaei
- Illawarra Health and Medical Research Institute, NSW 2522, Australia; Molecular Horizons, University of Wollongong, NSW 2522, Australia
| | - Longguang Jiang
- National Joint Biomdical Engineering Research Centre on Photodynamic Technologies, Fuzhou University, Fuzhou 350116, China
| | - Karen Fildes
- Illawarra Health and Medical Research Institute, NSW 2522, Australia; Graduate School of Medicine, University of Wollongong, NSW 2522, Australia
| | - Chen-Yi Cheung
- Department of Microbiology and Immunology, University of Otago, Otago 9016, New Zealand
| | - Darren Johnson
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, NY 10065, USA
| | - Daniel Bachovchin
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, NY 10065, USA; Chemical Biology Program, Memorial Sloan Kettering Cancer Centre, NY 10065, USA
| | - Gregory M Cook
- Department of Microbiology and Immunology, University of Otago, Otago 9016, New Zealand
| | - Mingdong Huang
- National Joint Biomdical Engineering Research Centre on Photodynamic Technologies, Fuzhou University, Fuzhou 350116, China
| | - Marie Ranson
- School of Chemistry and Molecular Bioscience, University of Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, NSW 2522, Australia; Molecular Horizons, University of Wollongong, NSW 2522, Australia.
| | - Michael J Kelso
- School of Chemistry and Molecular Bioscience, University of Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, NSW 2522, Australia; Molecular Horizons, University of Wollongong, NSW 2522, Australia.
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6
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Buckley BJ, Aboelela A, Minaei E, Jiang LX, Xu Z, Ali U, Fildes K, Cheung CY, Cook SM, Johnson DC, Bachovchin DA, Cook GM, Apte M, Huang M, Ranson M, Kelso MJ. 6-Substituted Hexamethylene Amiloride (HMA) Derivatives as Potent and Selective Inhibitors of the Human Urokinase Plasminogen Activator for Use in Cancer. J Med Chem 2018; 61:8299-8320. [PMID: 30130401 DOI: 10.1021/acs.jmedchem.8b00838] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Metastasis is the cause of death in the majority (∼90%) of malignant cancers. The oral potassium-sparing diuretic amiloride and its 5-substituted derivative 5 -N, N-(hexamethylene)amiloride (HMA) reportedly show robust antitumor/metastasis effects in multiple in vitro and animal models. These effects are likely due, at least in part, to inhibition of the urokinase plasminogen activator (uPA), a key protease determinant of cell invasiveness and metastasis. This study reports the discovery of 6-substituted HMA analogs that show nanomolar potency against uPA, high selectivity over related trypsin-like serine proteases, and minimal inhibitory effects against epithelial sodium channels (ENaC), the diuretic and antikaliuretic target of amiloride. Reductions in lung metastases were demonstrated for two analogs in a late-stage experimental mouse metastasis model, and one analog completely inhibited formation of liver metastases in an orthotopic xenograft mouse model of pancreatic cancer. The results support further evaluation of 6-substituted HMA derivatives as uPA-targeting anticancer drugs.
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Affiliation(s)
- Benjamin J Buckley
- Molecular Horizons and School of Chemistry & Molecular Bioscience , University of Wollongong , Wollongong , NSW 2522 , Australia.,Illawarra Health & Medical Research Institute , Wollongong , NSW 2522 , Australia
| | - Ashraf Aboelela
- Molecular Horizons and School of Chemistry & Molecular Bioscience , University of Wollongong , Wollongong , NSW 2522 , Australia.,Illawarra Health & Medical Research Institute , Wollongong , NSW 2522 , Australia
| | - Elahe Minaei
- Molecular Horizons and School of Chemistry & Molecular Bioscience , University of Wollongong , Wollongong , NSW 2522 , Australia.,Illawarra Health & Medical Research Institute , Wollongong , NSW 2522 , Australia
| | - Longguang X Jiang
- National Joint Biomedical Engineering Research Centre on Photodynamic Technologies , Fuzhou University , Fujian 350116 , China
| | - Zhihong Xu
- Pancreatic Research Group, South Western Sydney Clinical School , University of New South Wales, and Ingham Institute for Applied Medical Research , Liverpool , NSW 2170 , Australia
| | - Umar Ali
- Molecular Horizons and School of Chemistry & Molecular Bioscience , University of Wollongong , Wollongong , NSW 2522 , Australia.,Illawarra Health & Medical Research Institute , Wollongong , NSW 2522 , Australia
| | - Karen Fildes
- Illawarra Health & Medical Research Institute , Wollongong , NSW 2522 , Australia.,Graduate School of Medicine , University of Wollongong , Wollongong , NSW 2522 , Australia
| | - Chen-Yi Cheung
- Department of Microbiology and Immunology , University of Otago , Otago 9016 , New Zealand
| | - Simon M Cook
- Illawarra Health & Medical Research Institute , Wollongong , NSW 2522 , Australia
| | - Darren C Johnson
- Tri-Institutional PhD Program in Chemical Biology , Memorial Sloan Kettering Cancer Center , New York , New York 10065 , United States
| | - Daniel A Bachovchin
- Tri-Institutional PhD Program in Chemical Biology , Memorial Sloan Kettering Cancer Center , New York , New York 10065 , United States.,Chemical Biology Program , Memorial Sloan Kettering Cancer Center , New York , New York 10065 , United States
| | - Gregory M Cook
- Department of Microbiology and Immunology , University of Otago , Otago 9016 , New Zealand
| | - Minoti Apte
- Pancreatic Research Group, South Western Sydney Clinical School , University of New South Wales, and Ingham Institute for Applied Medical Research , Liverpool , NSW 2170 , Australia
| | - Mingdong Huang
- National Joint Biomedical Engineering Research Centre on Photodynamic Technologies , Fuzhou University , Fujian 350116 , China
| | - Marie Ranson
- Molecular Horizons and School of Chemistry & Molecular Bioscience , University of Wollongong , Wollongong , NSW 2522 , Australia.,Illawarra Health & Medical Research Institute , Wollongong , NSW 2522 , Australia
| | - Michael J Kelso
- Molecular Horizons and School of Chemistry & Molecular Bioscience , University of Wollongong , Wollongong , NSW 2522 , Australia.,Illawarra Health & Medical Research Institute , Wollongong , NSW 2522 , Australia
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7
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Islam I, Yuan S, West CW, Adler M, Bothe U, Bryant J, Chang Z, Chu K, Emayan K, Gualtieri G, Ho E, Light D, Mallari C, Morser J, Phillips G, Schaefer C, Sukovich D, Whitlow M, Chen D, Buckman BO. Discovery of selective urokinase plasminogen activator (uPA) inhibitors as a potential treatment for multiple sclerosis. Bioorg Med Chem Lett 2018; 28:3372-3375. [PMID: 30201291 DOI: 10.1016/j.bmcl.2018.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 08/29/2018] [Accepted: 09/01/2018] [Indexed: 11/28/2022]
Abstract
We report here the design and synthesis of a novel series of benzylamines that are potent and selective inhibitors of uPA with promising oral availability in rat. Further evaluation of one representative (ZK824859) of the new structural class showed that this compound lowered clinical scores when dosed in either acute or chronic mouse EAE models, suggesting that uPA inhibitors of this type could be useful for the treatment of multiple sclerosis.
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Affiliation(s)
- Imadul Islam
- Medical Core Facility and Research Platforms, King Abdullah International Medical Research Center/King Saud Bin, Abdulaziz University for Health Sciences, Ministry of National Guard Health Affairs, Riyadh 11426, Saudi Arabia; Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States.
| | - Shendong Yuan
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Christopher W West
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Marc Adler
- Department of Biophysics, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Ulrich Bothe
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States; Research and Development Pharmaceutical, Bayer AG, 13342 Berlin, Germany
| | - Judi Bryant
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Zheng Chang
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Kieu Chu
- Department of Molecular Pharmacology, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Kumar Emayan
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Giovanna Gualtieri
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Elena Ho
- Department of Animal Pharmacology, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - David Light
- Department of Antibody Technology, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Cornell Mallari
- Department of Animal Pharmacology, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - John Morser
- Cardiovascular Department, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Gary Phillips
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Caralee Schaefer
- Department of Animal Pharmacology, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Drew Sukovich
- Department of Molecular Pharmacology, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Marc Whitlow
- Department of Biophysics, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Deborah Chen
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
| | - Brad O Buckman
- Department of Medicinal Chemistry, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94804, United States
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8
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Xu P, Andreasen PA, Huang M. Structural Principles in the Development of Cyclic Peptidic Enzyme Inhibitors. Int J Biol Sci 2017; 13:1222-1233. [PMID: 29104489 PMCID: PMC5666521 DOI: 10.7150/ijbs.21597] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 08/28/2017] [Indexed: 01/23/2023] Open
Abstract
This review summarizes our studies in the development of small cyclic peptides for specifically modulating enzyme activity. Serine proteases share highly similar active sites but perform diverse physiological and pathological functions. From a phage-display peptide library, we isolated two mono-cyclic peptides, upain-1 (CSWRGLENHRMC) and mupain-1 (CPAYSRYLDC), which inhibit the activity of human and murine urokinase-type plasminogen activators (huPA and muPA) with Ki values in the micromolar or sub-micromolar range, respectively. The following affinity maturations significantly enhanced the potencies of the two peptides, 10-fold and >250-fold for upain-1 and mupain-1, respectively. The most potent muPA inhibitor has a potency (Ki = 2 nM) and specificity comparable to mono-clonal antibodies. Furthermore, we also found an unusual feature of mupain-1 that its inhibitory potency can be enhanced by increasing the flexibility, which challenges the traditional viewpoint that higher rigidity leading to higher affinity. Moreover, by changing a few key residues, we converted mupain-1 from a uPA inhibitor to inhibitors of other serine proteases, including plasma kallikrein (PK) and coagulation factor XIa (fXIa). PK and fXIa inhibitors showed Ki values in the low nanomolar range and high specificity. Our studies demonstrate the versatility of small cyclic peptides to engineer inhibitory potency against serine proteases and to provide a new strategy for generating peptide inhibitors of serine proteases.
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Affiliation(s)
- Peng Xu
- State Key Laboratory of Structural Chemistry and Danish-Chinese Centre for Proteases and Cancer, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P.R. China
| | - Peter A Andreasen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, 8000, Denmark
| | - Mingdong Huang
- State Key Laboratory of Structural Chemistry and Danish-Chinese Centre for Proteases and Cancer, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P.R. China.,College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116, P.R. China
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9
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Sa R, Fang L, Huang M, Li Q, Wei Y, Wu K. Evaluation of interactions between urokinase plasminogen and inhibitors using molecular dynamic simulation and free-energy calculation. J Phys Chem A 2014; 118:9113-9. [PMID: 24984238 DOI: 10.1021/jp5064319] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The binding modes of urokinase-type plasminogen activator (uPA) with five inhibitors (1-(7-sulfonamidoisoquinolinyl) guanidine derivatives) were predicted based on molecular dynamic simulations. MM/PBSA free-energy calculations and MM/GBSA free-energy decomposition analyses were performed on the studied complexes. The calculated binding free energies are reasonably consistent with the experimental results. The free-energy decomposition analyses elucidate the different contributions of the energy of some favorable residues in the interactions between protein and ligand of each complex. The results indicate that the inhibitors mainly interact with the S1 pocket of uPA, wherein the hydrogen bonds and the interactions between guanidines and the corresponding residues play an important role. Moreover, hydrogen bond analyses show the water-mediated hydrogen-bond network near the S1 pocket between uPA, and the ligand probably leads to excellent selectivity of these inhibitors on uPA.
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Affiliation(s)
- Rongjian Sa
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter , 155 Yangqiao Road West, Fuzhou, Fujian 350002, People's Republic of China
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10
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Wendt B, Cramer RD. Challenging the gold standard for 3D-QSAR: template CoMFA versus X-ray alignment. J Comput Aided Mol Des 2014; 28:803-24. [PMID: 24934658 DOI: 10.1007/s10822-014-9761-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 06/05/2014] [Indexed: 11/26/2022]
Abstract
X-ray-based alignments of bioactive compounds are commonly used to correlate structural changes with changes in potencies, ultimately leading to three-dimensional quantitative structure-activity relationships such as CoMFA or CoMSIA models that can provide further guidance for the design of new compounds. We have analyzed data sets where the alignment of the compounds is entirely based on experimentally derived ligand poses from X-ray-crystallography. We developed CoMFA and CoMSIA models from these X-ray-determined receptor-bound conformations and compared the results with models generated from ligand-centric Template CoMFA, finding that the fluctuations in the positions and conformations of compounds dominate X-ray-based alignments can yield poorer predictions than those from the self-consistent template CoMFA alignments. Also, when there exist multiple different binding modes, structural interpretation in terms of binding site constraints can often be simpler with template-based alignments than with X-ray-based alignments.
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Affiliation(s)
- Bernd Wendt
- Certara, Martin-Kollar-Str. 17, 81829, Munich, Germany,
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11
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Massey AP, Harley WR, Pasupuleti N, Gorin FA, Nantz MH. 2-Amidino analogs of glycine-amiloride conjugates: inhibitors of urokinase-type plasminogen activator. Bioorg Med Chem Lett 2012; 22:2635-9. [PMID: 22366654 DOI: 10.1016/j.bmcl.2011.12.123] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 12/23/2011] [Accepted: 12/27/2011] [Indexed: 10/14/2022]
Abstract
The relative non-toxicity of the diuretic amiloride, coupled with its selective inhibition of the protease urokinase plasminogen activator (uPA), makes this compound class attractive for structure-activity studies. Herein we substituted the C(2)-acylguanidine of C(5)-glycyl-amiloride with amidine and amidoxime groups. The data show the importance of maintaining C(5)-hydrophobicity. The C(5)-benzylglycine analogs containing either C(2)-acylguanidine or amidine inhibited uPA with an IC(50) ranging from 3 to 7 μM and were cytotoxic to human U87 malignant glioma cells.
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Affiliation(s)
- Archna P Massey
- Department of Chemistry, University of Louisville, Louisville, KY 40292, USA
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12
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Gohda K, Teno N, Wanaka K, Tsuda Y. Predicting subsite interactions of plasmin with substrates and inhibitors through computational docking analysis. J Enzyme Inhib Med Chem 2011; 27:571-7. [DOI: 10.3109/14756366.2011.603129] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Keigo Gohda
- Computer-Aided Molecular Modeling Research Center, Kansai (CAMM-Kansai),
Kobe, Japan
| | - Naoki Teno
- Faculty of Pharmaceutical Science, Hiroshima International University,
Kure, Japan
| | - Keiko Wanaka
- Kobe Research Projects on Thrombosis and Haemostasis,
Kobe, Japan
| | - Yuko Tsuda
- Faculty of Pharmaceutical Sciences, Kobe Gakuin University,
Kobe, Japan
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13
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Markowska A, Bruzgo I, Midura-Nowaczek K. Synthesis and activity of amides of tripeptides as potential urokinase inhibitors. J Enzyme Inhib Med Chem 2009; 25:139-42. [DOI: 10.3109/14756360903049042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Agnieszka Markowska
- Department of Organic Chemistry, Medical University of Bialystok, Bialystok, Poland
| | - Irena Bruzgo
- Department of Organic Chemistry, Medical University of Bialystok, Bialystok, Poland
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14
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Identification of orally bioavailable, non-amidine inhibitors of Urokinase Plasminogen Activator (uPA). Bioorg Med Chem Lett 2009; 19:5712-5. [DOI: 10.1016/j.bmcl.2009.08.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 08/01/2009] [Accepted: 08/04/2009] [Indexed: 11/20/2022]
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15
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Henrich S, Feierberg I, Wang T, Blomberg N, Wade RC. Comparative binding energy analysis for binding affinity and target selectivity prediction. Proteins 2009; 78:135-53. [DOI: 10.1002/prot.22579] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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16
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Zesławska E, Stürzebecher J, Oleksyn BJ. Geometry of GPPE binding to picrate and to the urokinase type plasminogen activator. Bioorg Med Chem Lett 2007; 17:6212-5. [PMID: 17905583 DOI: 10.1016/j.bmcl.2007.09.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 08/31/2007] [Accepted: 09/05/2007] [Indexed: 10/22/2022]
Abstract
Crystal structure of 2-(4-guanidynephenyl)-1-phenyl-ethanone (GPPE) in two different environments was determined in order to compare the binding geometry of these compound to a simple picrate anion and to protein, urokinase-type plasminogen activator (uPA), which may be treated as a target for anti-cancer drugs. It was shown that the conformation and the hydrogen-bonding formation by GPPE molecule are similar in both environments, but several important differences were discovered and described.
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Affiliation(s)
- Ewa Zesławska
- Department of Chemistry, Pedagogical University, ul. Podchorazych 2, 30-084 Kraków, Poland
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17
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Fish PV, Barber CG, Brown DG, Butt R, Collis MG, Dickinson RP, Henry BT, Horne VA, Huggins JP, King E, O'Gara M, McCleverty D, McIntosh F, Phillips C, Webster R. Selective Urokinase-Type Plasminogen Activator Inhibitors. 4. 1-(7-Sulfonamidoisoquinolinyl)guanidines†. J Med Chem 2007; 50:2341-51. [PMID: 17447747 DOI: 10.1021/jm061066t] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1-isoquinolinylguanidines were previously disclosed as potent and selective inhibitors of urokinase-type plasminogen activator (uPA). Further investigation of this template has revealed that incorporation of a 7-sulfonamide group furnishes a new series of potent and highly selective uPA inhibitors. Potency and selectivity can be achieved with sulfonamides derived from a variety of amines and is further enhanced by the incorporation of sulfonamides derived from amino acids. The binding mode of these 1-isoquinolinylguanidines has been investigated by X-ray cocrystallization studies. uPA inhibitor 26 was selected for further evaluation based on its excellent enzyme potency (Ki 10 nM) and selectivity profile (4000-fold versus tPA and 2700-fold versus plasmin). In vitro, compound 26 is able to inhibit exogenous uPA in human chronic wound fluid (IC50=0.89 microM). In vivo, in a porcine acute excisional wound model, following topical delivery, compound 26 is able to penetrate into pig wounds and inhibit exogenous uPA activity with no adverse effect on wound healing parameters. On the basis of this profile, compound 26 (UK-371,804) was selected as a candidate for further preclinical evaluation for the treatment of chronic dermal ulcers.
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Affiliation(s)
- Paul V Fish
- Department of Discovery Chemistry, Pfizer Global Research and Development, Sandwich, Kent, CT13 9NJ, UK.
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18
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19
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Zesławska E, Jacob U, Stürzebecher J, Oleksyn BJ. The crystal structures of 3-TAPAP in complexes with the urokinase-type plasminogen activator and picrate. Bioorg Med Chem Lett 2006; 16:228-34. [PMID: 16202591 DOI: 10.1016/j.bmcl.2005.08.089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Revised: 08/11/2005] [Accepted: 08/30/2005] [Indexed: 11/16/2022]
Abstract
The urokinase-type plasminogen activator (uPA) is a protein involved in tissue remodeling and other biological processes. The inhibitors of uPA have been shown to prevent the spread of metastasis and tumor growth, and accordingly this enzyme is widely accepted as a promising anticancer target. In this work, we have investigated the conformation of the uPA inhibitor 3-TAPAP in two different crystalline environments of a picrate and a uPA complex. These structures were compared to the known structure of the 3-TAPAP in the complex with trypsin. In the complexes with the proteins, trypsin, and uPA, the binding mode of 3-TAPAP is similar. A larger difference in the conformation, in the comparison to these structures, has been observed by us in the 3-TAPAP picrate crystal. This observation contradicts the hypothesis that 3-TAPAP derivatives inhibit serine proteinases in preformed stable conformations.
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Affiliation(s)
- Ewa Zesławska
- Department of Chemistry, Pedagogical University, ul. Podchorazych 2, 30-084 Kraków, Poland
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20
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Bhongade BA, Gadad AK. Insight into the Structural Requirements of Urokinase-Type Plasminogen Activator Inhibitors Based on 3D QSAR CoMFA/CoMSIA Models. J Med Chem 2005; 49:475-89. [PMID: 16420035 DOI: 10.1021/jm050149r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Urokinase-type plasminogen activator (uPA), a trypsin-like serine protease, has been implicated in large number of malignancies, tumor cell invasion, angiogenesis and metastasis; hence, the potent and selective inhibitors of uPA may therefore be therapeutically useful drugs for treatment of various forms of cancer. A three-dimensional quantitative structure-activity relationship (3D QSAR) study was performed on five different chemical series reported as selective uPA inhibitors employing comparative molecular field analysis (CoMFA)/comparative molecular similarity indices analysis (CoMSIA) techniques to investigate the structural requirements for substrates and derive a predictive model that may be used for the design of novel uPA inhibitors. ClogP has been used as an additional descriptor in the CoMFA analysis to study the effects of lipophilic parameters on activity. Inclusion of ClogP did not improve the models significantly and exhibited comparable correlation coefficients with CoMFA steric and electrostatic models. 3D QSAR models were derived for 2-pyridinylguanidines (training set N = 25, test set N = 8), 4-aminoarylguanidines and 4-aminoarylbenzamidines (training set N = 29, test set N = 8), thiophene-2-carboxamindines (training set N = 64, test set N = 19), 2-naphthamidines (training set N = 32, test set N = 8), and 1-isoquinolinylguanidines (training set N = 29, test set N = 7). The CoMFA models with steric and electrostatic fields exhibited r(2)(cv) 0.452-0.722, r(2)(ncv) 0.812-0.986, r(2)(pred) 0.597-0.870, whereas CoMFA ClogP models showed r(2)(cv) 0.420-0.707, r(2)(ncv) 0.849-0.957, r(2)(pred) 0.600-0.870. The CoMSIA models displayed r(2)(cv) 0.663-0.729, r(2)(ncv) 0.909-0.998, r(2)(pred) 0.554-0.855. 3D contour maps generated from these models were analyzed individually, which provides the regions in space where interactive fields may influence the activity. The superimposition of contour maps on the active site of serine proteases additionally helps in understanding the structural requirements of these inhibitors. Further, the predictive ability of 3D QSAR models was affirmed by predicting the activity of novel 2-naphthamidines. 3D QSAR models developed may be used in designing and predicting the uPA inhibitory activity of novel molecules.
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Affiliation(s)
- Bhoomendra A Bhongade
- Department of Medicinal Chemistry, College of Pharmacy, J. N. Medical College, Belgaum 590 010, Karnataka, India
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21
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Cummings MD, DesJarlais RL, Gibbs AC, Mohan V, Jaeger EP. Comparison of automated docking programs as virtual screening tools. J Med Chem 2005; 48:962-76. [PMID: 15715466 DOI: 10.1021/jm049798d] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The performance of several commercially available docking programs is compared in the context of virtual screening. Five different protein targets are used, each with several known ligands. The simulated screening deck comprised 1000 molecules from a cleansed version of the MDL drug data report and 49 known ligands. For many of the known ligands, crystal structures of the relevant protein-ligand complexes were available. We attempted to run experiments with each docking method that were as similar as possible. For a given docking method, hit rates were improved versus what would be expected for random selection for most protein targets. However, the ability to prioritize known ligands on the basis of docking poses that resemble known crystal structures is both method- and target-dependent.
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Affiliation(s)
- Maxwell D Cummings
- Johnson & Johnson Pharmaceutical Research & Development, Eagleview Corporate Center, 665 Stockton Drive, Exton, Pennsylvania 19341, USA.
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22
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23
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Wendt MD, Geyer A, McClellan WJ, Rockway TW, Weitzberg M, Zhao X, Mantei R, Stewart K, Nienaber V, Klinghofer V, Giranda VL. Interaction with the S1 beta-pocket of urokinase: 8-heterocycle substituted and 6,8-disubstituted 2-naphthamidine urokinase inhibitors. Bioorg Med Chem Lett 2005; 14:3063-8. [PMID: 15149645 DOI: 10.1016/j.bmcl.2004.04.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2004] [Revised: 04/12/2004] [Accepted: 04/12/2004] [Indexed: 10/26/2022]
Abstract
Several 8-substituted 2-naphthamidine-based inhibitors of the serine protease urokinase plasminogen activator (uPA) are described. Direct attachment of five-membered saturated or unsaturated rings improved inhibitor performance; substitution with sulfones further improved binding profiles. Combination of these substituents or of previously described NH-linked heteroaromatic rings with 6-phenyl amide substituents provided further enhancements to potency and selectivity.
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Affiliation(s)
- Michael D Wendt
- Cancer Research, Global Pharmaceutical R & D, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064-6101, USA.
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24
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Bruncko M, McClellan WJ, Wendt MD, Sauer DR, Geyer A, Dalton CR, Kaminski MA, Weitzberg M, Gong J, Dellaria JF, Mantei R, Zhao X, Nienaber VL, Stewart K, Klinghofer V, Bouska J, Rockway TW, Giranda VL. Naphthamidine urokinase plasminogen activator inhibitors with improved pharmacokinetic properties. Bioorg Med Chem Lett 2005; 15:93-8. [PMID: 15582418 DOI: 10.1016/j.bmcl.2004.10.026] [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: 08/04/2004] [Revised: 10/06/2004] [Accepted: 10/09/2004] [Indexed: 10/26/2022]
Abstract
A series of non-amide-linked 6-substituted-2-naphthamidine urokinase plasminogen activator (uPA) inhibitors are described. These compounds possess excellent binding activities and selectivities with significantly improved pharmacokinetic profiles versus previously described amide-linked inhibitors.
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Affiliation(s)
- Milan Bruncko
- Cancer Research, Global Pharmaceutical R&D, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064-6101, USA.
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25
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Katz BA, Luong C, Ho JD, Somoza JR, Gjerstad E, Tang J, Williams SR, Verner E, Mackman RL, Young WB, Sprengeler PA, Chan H, Mortara K, Janc JW, McGrath ME. Dissecting and Designing Inhibitor Selectivity Determinants at the S1 Site Using an Artificial Ala190 Protease (Ala190 uPA). J Mol Biol 2004; 344:527-47. [PMID: 15522303 DOI: 10.1016/j.jmb.2004.09.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Revised: 09/14/2004] [Accepted: 09/15/2004] [Indexed: 11/21/2022]
Abstract
A site-directed mutant of the serine protease urokinase-type plasminogen activator (uPA), was produced to assess the contribution of the Ser190 side-chain to the affinity and selectivity of lead uPA inhibitors in the absence of other differences present in comparisons of natural proteases. Crystallography and enzymology involving WT and Ala190 uPA were used to calculate free energy binding contributions of hydrogen bonds involving the Ser190 hydroxyl group (O(gamma)(Ser190)) responsible for the remarkable selectivity of 6-halo-5-amidinoindole and 6-halo-5-amidinobenzimidazole inhibitors toward uPA and against natural Ala190 protease anti-targets. Crystal structures of uPA complexes of novel, active site-directed arylguanidine and 2-aminobenzimidazole inhibitors of WT uPA, together with associated K(i) values for WT and Ala190 uPA, also indicate a significant role of Ser190 in the binding of these classes of uPA inhibitors. Structures and associated K(i) values for a lead inhibitor (CA-11) bound to uPA and to five other proteases, as well as for other leads bound to multiple proteases, help reveal the features responsible for the potency (K(i)=11nM) and selectivity of the remarkably small inhibitor, CA-11. The 6-fluoro-5-amidinobenzimidzole, CA-11, is more than 1000-fold selective against natural Ala190 protease anti-targets, and more than 100-fold selective against other Ser190 anti-targets.
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Affiliation(s)
- Bradley A Katz
- Celera, 180 Kimball Way, South San Francisco, CA 94080, USA.
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26
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Wendt MD, Rockway TW, Geyer A, McClellan W, Weitzberg M, Zhao X, Mantei R, Nienaber VL, Stewart K, Klinghofer V, Giranda VL. Identification of Novel Binding Interactions in the Development of Potent, Selective 2-Naphthamidine Inhibitors of Urokinase. Synthesis, Structural Analysis, and SAR of N-Phenyl Amide 6-Substitution. J Med Chem 2003; 47:303-24. [PMID: 14711304 DOI: 10.1021/jm0300072] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The preparation and assessment of biological activity of 6-substituted 2-naphthamidine inhibitors of the serine protease urokinase plasminogen activator (uPA, or urokinase) is described. 2-Naphthamidine was chosen as a starting point based on synthetic considerations and on modeling of substituent vectors. Phenyl amides at the 6-position were found to improve binding; replacement of the amide with other two-atom linkers proved ineffective. The phenyl group itself is situated near the S1' subsite; substitutions off of the phenyl group accessed S1' and other distant binding regions. Three new points of interaction were defined and explored through ring substitution. A solvent-exposed salt bridge with the Asp60A carboxylate was formed using a 4-alkylamino group, improving affinity to K(i) = 40 nM. Inhibitors also accessed two hydrophobic regions. One interaction is characterized by a tight hydrophobic fit made with a small dimple largely defined by His57 and His99; a weaker, less specific interaction involves alkyl groups reaching into the broad prime-side protein binding region near Val41 and the Cys42-Cys58 disulfide, displacing water molecules and leading to small gains in activity. Many inhibitors accessed two of these three regions. Affinities range as low as K(i) = 6 nM, and many compounds had K(i) < 100 nM, while moderate to excellent selectivity was gained versus four of five members of a panel of relevant serine proteases. Also, some selectivity against trypsin was generated via the interaction with Asp60A. X-ray structures of many of these compounds were used to inform our inhibitor design and to increase our understanding of key interactions. In combination with our exploration of 8-substitution patterns, we have identified a number of novel binding interactions for uPA inhibitors.
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Affiliation(s)
- Michael D Wendt
- Cancer Research and Structural Biology, Global Pharmaceutical R & D, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064-6101, USA.
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27
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Magdolen V, Krüger A, Sato S, Nagel J, Sperl S, Reuning U, Rettenberger P, Magdolen U, Schmitt M. Inhibition of the tumor-associated urokinase-type plasminogen activation system: effects of high-level synthesis of soluble urokinase receptor in ovarian and breast cancer cells in vitro and in vivo. Recent Results Cancer Res 2003; 162:43-63. [PMID: 12790320 DOI: 10.1007/978-3-642-59349-9_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Tumor cell invasion and metastasis depend on the coordinated and temporal expression of proteolytic enzymes to degrade the surrounding extracellular matrix and of adhesion molecules to remodel cell-cell and/or cell-matrix attachments. The tumor cell-associated urokinase-type plasminogen activator system, consisting of the serine protease uPA, its substrate plasminogen, its membrane-bound receptor uPAR, as well as its inhibitors PAI-1 and PAI-2, plays an important role in these pericellular processes. Especially, association of the proteolytic activity of uPA with the cell surface via interaction with uPAR significantly increases the invasive capacity of tumor cells. Consequently, various approaches have been pursued to interfere with the expression or activity of uPA and/or uPAR, including antisense strategies and the development of active-site inhibitors of uPA or inhibitors of uPA/uPAR interaction. In this review, we focus on the results obtained in vitro and in vivo with tumor cells producing high levels of a recombinant soluble form of uPAR, which efficiently inhibits uPA binding to cell surface-associated uPAR and, by this, acts as a scavenger for uPA.
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Affiliation(s)
- Viktor Magdolen
- Klinische Forschergruppe der Frauenklinik der TU München, Klinikum rechts der Isar, Ismaninger Str. 22, 81675 Munich, Germany
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28
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Zeslawska E, Jacob U, Schweinitz A, Coombs G, Bode W, Madison E. Crystals of urokinase type plasminogen activator complexes reveal the binding mode of peptidomimetic inhibitors. J Mol Biol 2003; 328:109-18. [PMID: 12684001 DOI: 10.1016/s0022-2836(03)00267-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Urokinase type plasminogen activator (uPA), a trypsin-like serine proteinase, plays an important role in normal tissue re-modelling, cell adhesion, and cell motility. In addition, studies utilizing normal animals and potent, selective uPA inhibitors or genetically modified mice that lack functional uPA genes have demonstrated that uPA can significantly enhance tumor initiation, growth, progression and metastasis, strongly suggesting that this enzyme may be a promising anti-cancer target. We have investigated the structure-activity relationship (SAR) of peptidomimetic inhibitors of uPA and solved high resolution X-ray structures of key, lead small molecule inhibitors (e.g. phenethylsulfonamidino(P4)-D-seryl(P3)-L-alanyl(P2)-L-argininal(P1) and derivatives thereof) in complex with the uPA proteinase domain. These potent inhibitors are highly selective for uPA. The non-natural D-seryl residue present at the P3 position in these inhibitors contributes substantially to both potency and selectivity because, due to its D-configuration, its side-chain binds in the S4 pocket to interact with the uPA unique residues Leu97b and His99. Additional potency and selectivity can be achieved by optimizing the inhibitor P4 residue to bind a pocket, known as S1sub or S1beta, that is adjacent to the primary specificity pocket of uPA.
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Affiliation(s)
- Ewa Zeslawska
- Pedagogical University, Department of Chemistry, Podchorazych 2, 30-084 Cracow, Poland
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29
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Hillisch A, Hilgenfeld R. The role of protein 3D-structures in the drug discovery process. EXS 2003:157-81. [PMID: 12613176 DOI: 10.1007/978-3-0348-7997-2_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
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30
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Rauh D, Reyda S, Klebe G, Stubbs MT. Trypsin mutants for structure-based drug design: expression, refolding and crystallisation. Biol Chem 2002; 383:1309-14. [PMID: 12437122 DOI: 10.1515/bc.2002.148] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
New techniques in drug discovery are essential for the fast and efficient development of novel innovative drugs to deal with the challenges of the future. Structure determinations of various members of serine proteinases have provided a basis for computer-based drug design within this class of enzymes. In many proteins of interest, however, this course is blocked through a lack of suitable crystals. As a strategy for circumventing such problems, we have investigated the use of surrogate proteins for studying protein-ligand interactions. To test the feasibility of this approach, we have chosen bovine trypsin as a scaffold to reconstruct the ligand binding site of factor Xa. The simple modular design of trypsin, its readiness to crystallise and straightforward handling lends itself to such drug design by proxy. The expression, folding, purification, crystallographic and kinetic characterisation of bovine trypsin forms with factor Xa phenotype are presented.
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Affiliation(s)
- Daniel Rauh
- Institut für Pharmazeutische Chemie der Philipps-Universität Marburg, Germany
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31
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Mueller MM, Sperl S, Stürzebecher J, Bode W, Moroder L. (R)-3-Amidinophenylalanine-derived inhibitors of factor Xa with a novel active-site binding mode. Biol Chem 2002; 383:1185-91. [PMID: 12437104 DOI: 10.1515/bc.2002.130] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A putative non-substrate like binding mode of (R)-3-amidinophenylalanine derivatives to factor Xa, as derived from modeling experiments based on X-ray analysis of their complexes with trypsin, was used to design a new generation of inhibitors. However, the resulting inhibitory potencies were not at all consistent with the working assumption, although with an adamantyl-ureido derivative of (R)-3-amidinophenylalanine phenetyl amide a highly selective nanomolar inhibition of factor Xa was achieved. The X-ray analysis of the complex of this ligand with factor Xa revealed an unexpected new binding mode, of which the most important feature is the interaction of the C-terminal aryl moiety with a hydrophobic subregion of the S1 subsite, while the adamantyl group occupies the hydrophobic S3/S4 subsites of the enzyme.
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32
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Rudolph MJ, Illig CR, Subasinghe NL, Wilson KJ, Hoffman JB, Randle T, Green D, Molloy CJ, Soll RM, Lewandowski F, Zhang M, Bone R, Spurlino JC, Deckman IC, Manthey C, Sharp C, Maguire D, Grasberger BL, DesJarlais RL, Zhou Z. Design and synthesis of 4,5-disubstituted-thiophene-2-amidines as potent urokinase inhibitors. Bioorg Med Chem Lett 2002; 12:491-5. [PMID: 11814826 DOI: 10.1016/s0960-894x(01)00787-9] [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: 10/27/2022]
Abstract
A study of the S1 binding of lead 5-methylthiothiophene amidine 3, an inhibitor of urokinase-type plasminogen activator, was undertaken by the introduction of a variety of substituents at the thiophene 5-position. The 5-alkyl substituted and unsubstituted thiophenes were prepared using organolithium chemistry. Heteroatom substituents were introduced at the 5-position using a novel displacement reaction of 5-methylsulfonylthiophenes and the corresponding oxygen or sulfur anions. Small alkyl group substitution at the 5-position provided inhibitors equipotent with but possessing improved solubility.
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Affiliation(s)
- M Jonathan Rudolph
- 3-Dimensional Pharmaceuticals Inc., 665 Stockton Drive, Exton, PA 19341, USA.
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33
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Barber CG, Dickinson RP, Horne VA. Selective urokinase-type plasminogen activator (uPA) inhibitors. Part 1: 2-Pyridinylguanidines. Bioorg Med Chem Lett 2002; 12:181-4. [PMID: 11755349 DOI: 10.1016/s0960-894x(01)00701-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The identification of 2-pyridinylguanidines (e.g., 27 and 28) as selective inhibitors of urokinase-type plasminogen activator (uPA) is described. The X-ray crystal structure of 27 has been determined, and modelling has been used to predict binding in the enzyme active site.
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Affiliation(s)
- Christopher G Barber
- Department of Discovery Chemistry, Pfizer Global Research and Development, Sandwich, Kent CT13 9NJ, UK.
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34
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Rosenberg S. New developments in the urokinase-type plasminogen activator system. Expert Opin Ther Targets 2001; 5:711-722. [PMID: 12540280 DOI: 10.1517/14728222.5.6.711] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The urokinase-type plasminogen activator (uPA) system plays a central role in control of cell surface proteolysis and extracellular matrix degradation. Components of this system are upregulated in a wide variety of human cancers and high levels of these proteins predict more rapid relapse and shorter survival. Recently, additional complexities in this system have been recognised, especially with regard to the roles of plasminogen activator inhibitor-1 (PAI-1), the urokinase receptor (uPAR) and urokinase:uPAR complexes. PAI-1 has been shown to play a major role in the process of pathological angiogenesis. The uPAR is involved as a key player both in proteolysis and cellular adhesion, where it is both an adhesion receptor itself for vitronectin and interacts with and modifies signalling from integrins. In addition, binding of uPA to the receptor can induce intracellular signalling via a number of different pathways, including integrins and G proteins. These new developments lead to a number of novel targets for drug discovery beyond better established enzyme inhibitors and receptor antagonists.
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Affiliation(s)
- Steven Rosenberg
- MCB Dept. Rm 229, University of California, Berkeley, California 94720-3206 USA.
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Katz BA, Sprengeler PA, Luong C, Verner E, Elrod K, Kirtley M, Janc J, Spencer JR, Breitenbucher JG, Hui H, McGee D, Allen D, Martelli A, Mackman RL. Engineering inhibitors highly selective for the S1 sites of Ser190 trypsin-like serine protease drug targets. CHEMISTRY & BIOLOGY 2001; 8:1107-21. [PMID: 11731301 DOI: 10.1016/s1074-5521(01)00084-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Involved or implicated in a wide spectrum of diseases, trypsin-like serine proteases comprise well studied drug targets and anti-targets that can be subdivided into two major classes. In one class there is a serine at position 190 at the S1 site, as in urokinase type plasminogen activator (urokinase or uPA) and factor VIIa, and in the other there is an alanine at 190, as in tissue type plasminogen activator (tPA) and factor Xa. A hydrogen bond unique to Ser190 protease-arylamidine complexes between O gamma(Ser190) and the inhibitor amidine confers an intrinsic preference for such inhibitors toward Ser190 proteases over Ala190 counterparts. RESULTS Based on the structural differences between the S1 sites of Ser190 and Ala190 protease-arylamidine complexes, we amplified the selectivity of amidine inhibitors toward uPA and against tPA, by factors as high as 220-fold, by incorporating a halo group ortho to the amidine of a lead inhibitor scaffold. Comparison of K(i) values of such halo-substituted and parent inhibitors toward a panel of Ser190 and Ala190 proteases demonstrates pronounced selectivity of the halo analogs for Ser190 proteases over Ala190 counterparts. Crystal structures of Ser190 proteases, uPA and trypsin, and of an Ala190 counterpart, thrombin, bound by a set of ortho (halo, amidino) aryl inhibitors and of non-halo parents reveal the structural basis of the exquisite selectivity and validate the design principle. CONCLUSIONS Remarkable selectivity enhancements of exceptionally small inhibitors are achieved toward the uPA target over the highly similar tPA anti-target through a single atom substitution on an otherwise relatively non-selective scaffold. Overall selectivities for uPA over tPA as high as 980-fold at physiological pH were realized. The increase in selectivity results from the displacement of a single bound water molecule common to the S1 site of both the uPA target and the tPA anti-target because of the ensuing deficit in hydrogen bonding of the arylamidine inhibitor when bound in the Ala190 protease anti-target.
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Affiliation(s)
- B A Katz
- Axys Pharmaceutical Corporation, 385 Oyster Point Boulevard, South San Francisco, CA 94080, USA.
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Verner E, Katz BA, Spencer JR, Allen D, Hataye J, Hruzewicz W, Hui HC, Kolesnikov A, Li Y, Luong C, Martelli A, Radika K, Rai R, She M, Shrader W, Sprengeler PA, Trapp S, Wang J, Young WB, Mackman RL. Development of serine protease inhibitors displaying a multicentered short (<2.3 A) hydrogen bond binding mode: inhibitors of urokinase-type plasminogen activator and factor Xa. J Med Chem 2001; 44:2753-71. [PMID: 11495587 DOI: 10.1021/jm0100638] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Novel scaffolds that bind to serine proteases through a unique network of short hydrogen bonds to the catalytic Ser195 have been developed. The resulting potent serine protease inhibitors were designed from lead molecule 2-(2-hydroxyphenyl)1H-benzoimidazole-5-carboxamidine, 6b, which is known to display several modes of binding. For instance, 6b can recruit zinc and bind in a manner similar to that reported by bis(5-amidino-2-benzimidazolyl)methane (BABIM) (Nature 1998, 391, 608-612).(1) Alternatively, 6b can bind in the absence of zinc through a multicentered network of short (<2.3 A) hydrogen bonds. The lead structure was optimized in the zinc-independent binding mode toward a panel of six human serine proteases to yield optimized inhibitors such as 2-(3-bromo-2-hydroxy-5-methylphenyl)-1H-indole-5-carboxamidine, 22a, and 2-(2-hydroxybiphenyl-3-yl)-1H-indole-5-carboxamidine, 22f. Structure-activity relationships determined that, apart from the amidine function, an indole or benzimidazole and an ortho substituted phenol group were also essential components for optimal potency. The affinities (K(i)) of 22a and 22f, for example, bearing these groups ranged from 8 to 600 nM toward a panel of six human serine proteases. High-resolution crystal structures revealed that the binding mode of these molecules in several of the enzymes was identical to that of 6b and involved short (<2.3 A) hydrogen bonds among the inhibitor hydroxyl oxygen, Ser195, and a water molecule trapped in the oxyanion hole. In summation, novel and potent trypsin-like serine protease inhibitors possessing a unique mode of binding have been discovered.
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Affiliation(s)
- E Verner
- Department of Medicinal Chemistry, Axys Pharmaceuticals Inc., 180 Kimball Way, South San Francisco, California 94080, USA
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37
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Connell RD, Beebe JS. Patent focus on cancer chemotherapeutics. III Angiogenesis agents: October 2000 – March 2001. Expert Opin Ther Pat 2001. [DOI: 10.1517/13543776.11.7.1171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Muehlenweg B, Sperl S, Magdolen V, Schmitt M, Harbeck N. Interference with the urokinase plasminogen activator system: a promising therapy concept for solid tumours. Expert Opin Biol Ther 2001; 1:683-91. [PMID: 11727504 DOI: 10.1517/14712598.1.4.683] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
There is abundant evidence that the plasminogen activator (PA) system with its key components uPA (urokinase-type plasminogen activator), its cell surface receptor uPA-R (CD87) and its inhibitor PAI-1 plays a key role in tumour invasion and metastasis. Elevated levels of these factors in tumour tissue are associated with tumour aggressiveness and poor patient outcome. Animal models suggest that the PA system is not essential for fertility or survival under physiological conditions. Thus, it seems well suited as a therapeutic target for patients with solid malignant tumours. Novel therapy concepts targeting the uPA system are currently being explored. A variety of different synthetic uPA inhibitor classes have been developed over the last decades. First generation inhibitors displayed a low uPA inhibitory potency combined with broad specificity. More recently, structure based design, x-ray crystallographic screening or NMR based screening have revealed a large number of new, potent and selective uPA-inhibitors. A few modern compounds have shown promising results in preclinical testing and are now ready for Phase I clinical studies. Other therapeutic strategies such as antagonists of uPA/uPA-R interaction or gene therapeutic approaches to suppress the uPA-system are still being evaluated in in vitro and in vivo models. For clinical application, a combination therapy targeting more than one of the interacting proteolytic pathways may be required for effective antiproteolytic therapy. In addition, antiproteolytic agents may provide additive or synergistic treatment benefits if used in combination together with conventional therapeutics, in particular in those solid tumours for which potent conventional regimens already exist.
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Affiliation(s)
- B Muehlenweg
- Wilex AG, Clinical Research Unit, Department of Obstetrics & Gynaecology, Technical University of Munich, D-81675 Munich, Germany
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Wilson KJ, Illig CR, Subasinghe N, Hoffman JB, Rudolph MJ, Soll R, Molloy CJ, Bone R, Green D, Randall T, Zhang M, Lewandowski FA, Zhou Z, Sharp C, Maguire D, Grasberger B, DesJarlais RL, Spurlino J. Synthesis of thiophene-2-carboxamidines containing 2-aminothiazoles and their biological evaluation as urokinase inhibitors. Bioorg Med Chem Lett 2001; 11:915-8. [PMID: 11294390 DOI: 10.1016/s0960-894x(01)00102-0] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The serine protease urokinase (uPa) has been implicated in the progression of both breast and prostate cancer. Utilizing structure based design, the synthesis of a series of substituted 4-[2-amino-1,3-thiazolyl]-thiophene-2-carboxamidines is described. Further optimization of this series by substitution of the terminal amine yielded urokinase inhibitors with excellent activities.
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Affiliation(s)
- K J Wilson
- 3-Dimensional Pharmaceuticals, Inc., Exton, PA 19341, USA.
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40
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Tranter R, Read JA, Jones R, Brady RL. Effector sites in the three-dimensional structure of mammalian sperm beta-acrosin. Structure 2000; 8:1179-88. [PMID: 11080640 DOI: 10.1016/s0969-2126(00)00523-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Proacrosin is a serine protease found specifically within the acrosomal vesicle of all mammalian spermatozoa. During fertilization proacrosin autoactivates to form beta-acrosin, in which there is a "light" chain cross-linked to a "heavy" chain by two disulphide bonds. beta-acrosin is thought to be multifunctional with roles in acrosomal exocytosis, as a receptor for zona pellucida proteins, and as a protease to facilitate penetration of spermatozoa into the egg. RESULTS The crystal structures of both ram and boar beta-acrosins have been solved in complex with p-aminobenzamidine to 2.1 A and 2.9 A resolution, respectively. Both enzymes comprise a heavy chain with structural homology to trypsin, and a light chain covalently associated in a similar manner to blood coagulation enzymes. In crystals of boar beta-acrosin, the carboxyl terminus of the heavy chain is inserted into the active site of the neighboring molecule. In both enzyme structures, there are distinctive positively charged surface "patches" close to the active site, which associate with carbohydrate from adjacent molecules and also bind sulfate ions. CONCLUSIONS From the three-dimensional structure of beta-acrosin, two separate effector sites are evident. First, proteolytic activity, believed to be important at various stages during fertilization, arises from the trypsin-like active site. Activity of this site may be autoregulated through intermolecular associations. Second, positively charged regions on the surface adjacent to the active site may act as receptors for binding zona pellucida glycoproteins. The spatial proximity of these two effector sites suggests there may be synergy between them.
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Affiliation(s)
- R Tranter
- Department of Biochemistry University of Bristol BS8 1TD, Bristol, United Kingdom
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Hajduk PJ, Boyd S, Nettesheim D, Nienaber V, Severin J, Smith R, Davidson D, Rockway T, Fesik SW. Identification of novel inhibitors of urokinase via NMR-based screening. J Med Chem 2000; 43:3862-6. [PMID: 11052791 DOI: 10.1021/jm0002228] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Using an NMR-based screen, a novel class of urokinase inhibitors were identified that contain a 2-aminobenzimidazole moiety. The inhibitory potency of this family of inhibitors is similar to that of inhibitors containing a guanidine or amidine group. However, unlike previously described guanidino- or amidino-based inhibitors which have pK(a) values greater than 9.0, urokinase inhibitors containing a 2-aminobenzimidazole have pK(a) values of 7.5. Thus, 2-aminobenzimidazoles may have improved pharmacokinetic properties which could increase the bioavailability of inhibitors which contain this moiety. A crystal structure of one of the lead inhibitors, 2-amino-5-hydroxybenzimidazole, complexed with urokinase reveals the electrostatic and hydrophobic interactions that stabilize complex formation and suggests nearby subsites that may be accessed to increase the potency of this new series of urokinase inhibitors.
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Affiliation(s)
- P J Hajduk
- Pharmaceutical Discovery Division, Abbott Laboratories, Abbott Park, Illinois 60064, USA
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Nienaber VL, Richardson PL, Klighofer V, Bouska JJ, Giranda VL, Greer J. Discovering novel ligands for macromolecules using X-ray crystallographic screening. Nat Biotechnol 2000; 18:1105-8. [PMID: 11017052 DOI: 10.1038/80319] [Citation(s) in RCA: 252] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The need to decrease the time scale for clinical compound discovery has led to innovations at several stages in the process, including genomics/proteomics for target identification, ultrahigh-throughput screening for lead identification, and structure-based drug design and combinatorial chemistry for lead optimization. A critical juncture in the process is the identification of a proper lead compound, because a poor choice may generate costly difficulties at later stages. Lead compounds are commonly identified from high-throughput screens of large compound libraries, derived from known substrates/inhibitors, or identified in computational prescreeusing X-ray crystal structures. Structural information is often consulted to efficiently optimize leads, but under the current paradigm, such data require preidentification and confirmation of compound binding. Here, we describe a new X-ray crystallography-driven screening technique that combines the steps of lead identification, structural assessment, and optimization. The method is rapid, efficient, and high-throughput, and it results in detailed crystallographic structure information. The utility of the method is demonstrated in the discovery and optimization of a new orally available class of urokinase inhibitors for the treatment of cancer.
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Affiliation(s)
- V L Nienaber
- Department of Structural Biology, Abbott Laboratories, Abbott Park, IL 60064-6098, USA.
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