1
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Mardikoraem M, Wang Z, Pascual N, Woldring D. Generative models for protein sequence modeling: recent advances and future directions. Brief Bioinform 2023; 24:bbad358. [PMID: 37864295 PMCID: PMC10589401 DOI: 10.1093/bib/bbad358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 09/08/2023] [Accepted: 09/12/2023] [Indexed: 10/22/2023] Open
Abstract
The widespread adoption of high-throughput omics technologies has exponentially increased the amount of protein sequence data involved in many salient disease pathways and their respective therapeutics and diagnostics. Despite the availability of large-scale sequence data, the lack of experimental fitness annotations underpins the need for self-supervised and unsupervised machine learning (ML) methods. These techniques leverage the meaningful features encoded in abundant unlabeled sequences to accomplish complex protein engineering tasks. Proficiency in the rapidly evolving fields of protein engineering and generative AI is required to realize the full potential of ML models as a tool for protein fitness landscape navigation. Here, we support this work by (i) providing an overview of the architecture and mathematical details of the most successful ML models applicable to sequence data (e.g. variational autoencoders, autoregressive models, generative adversarial neural networks, and diffusion models), (ii) guiding how to effectively implement these models on protein sequence data to predict fitness or generate high-fitness sequences and (iii) highlighting several successful studies that implement these techniques in protein engineering (from paratope regions and subcellular localization prediction to high-fitness sequences and protein design rules generation). By providing a comprehensive survey of model details, novel architecture developments, comparisons of model applications, and current challenges, this study intends to provide structured guidance and robust framework for delivering a prospective outlook in the ML-driven protein engineering field.
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Affiliation(s)
- Mehrsa Mardikoraem
- Michigan State University (MSU)‘s Department of Chemical Engineering and Materials Science
| | - Zirui Wang
- Regeneron Pharmaceuticals, Inc. Having received his B.S. in Chemical Engineering from MSU, he is currently pursuing a M.S. in Computer Science from Syracuse University
| | | | - Daniel Woldring
- MSU’s Department of Chemical Engineering and Materials Science and a member of MSU’s Institute for Quantitative Health Sciences and Engineering
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2
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Imiołek M, Winssinger N. Two-Helix Supramolecular Proteomimetic Binders Assembled via PNA-Assisted Disulfide Crosslinking. Chembiochem 2023; 24:e202200561. [PMID: 36349499 DOI: 10.1002/cbic.202200561] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 11/05/2022] [Indexed: 11/10/2022]
Abstract
Peptidic motifs folded in a defined conformation are able to inhibit protein-protein interactions (PPIs) covering large interfaces and as such they are biomedical molecules of interest. Mimicry of such natural structures with synthetically tractable constructs often requires complex scaffolding and extensive optimization to preserve the fidelity of binding to the target. Here, we present a novel proteomimetic strategy based on a 2-helix binding motif that is brought together by hybridization of peptide nucleic acids (PNA) and stabilized by a rationally positioned intermolecular disulfide crosslink. Using a solid phase synthesis approach (SPPS), the building blocks are easily accessible and such supramolecular peptide-PNA helical hybrids could be further coiled using precise templated chemistry. The elaboration of the structural design afforded high affinity SARS CoV-2 RBD (receptor binding domain) binders without interference with the underlying peptide sequence, creating a basis for a new architecture of supramolecular proteomimetics.
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Affiliation(s)
- Mateusz Imiołek
- Department of Organic Chemistry, Faculty of Science, NCCR Chemical Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Nicolas Winssinger
- Department of Organic Chemistry, Faculty of Science, NCCR Chemical Biology, University of Geneva, 1211, Geneva, Switzerland
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3
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Khatri B, Pramanick I, Malladi SK, Rajmani RS, Kumar S, Ghosh P, Sengupta N, Rahisuddin R, Kumar N, Kumaran S, Ringe RP, Varadarajan R, Dutta S, Chatterjee J. A dimeric proteomimetic prevents SARS-CoV-2 infection by dimerizing the spike protein. Nat Chem Biol 2022; 18:1046-1055. [PMID: 35654847 PMCID: PMC9512702 DOI: 10.1038/s41589-022-01060-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 05/10/2022] [Indexed: 11/17/2022]
Abstract
Protein tertiary structure mimetics are valuable tools to target large protein-protein interaction interfaces. Here, we demonstrate a strategy for designing dimeric helix-hairpin motifs from a previously reported three-helix-bundle miniprotein that targets the receptor-binding domain (RBD) of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Through truncation of the third helix and optimization of the interhelical loop residues of the miniprotein, we developed a thermostable dimeric helix-hairpin. The dimeric four-helix bundle competes with the human angiotensin-converting enzyme 2 (ACE2) in binding to RBD with 2:2 stoichiometry. Cryogenic-electron microscopy revealed the formation of dimeric spike ectodomain trimer by the four-helix bundle, where all the three RBDs from either spike protein are attached head-to-head in an open conformation, revealing a novel mechanism for virus neutralization. The proteomimetic protects hamsters from high dose viral challenge with replicative SARS-CoV-2 viruses, demonstrating the promise of this class of peptides that inhibit protein-protein interaction through target dimerization.
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Affiliation(s)
- Bhavesh Khatri
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bangalore, India
| | - Ishika Pramanick
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bangalore, India
| | | | - Raju S Rajmani
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bangalore, India
| | - Sahil Kumar
- Virology Unit, Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, India
| | - Pritha Ghosh
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bangalore, India
| | - Nayanika Sengupta
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bangalore, India
| | - R Rahisuddin
- Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, India
| | - Narender Kumar
- Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, India
| | - S Kumaran
- Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, India
| | - Rajesh P Ringe
- Virology Unit, Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh, India
| | | | - Somnath Dutta
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bangalore, India.
| | - Jayanta Chatterjee
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bangalore, India.
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4
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Luo R, Liu H, Cheng Z. Protein scaffolds: Antibody alternative for cancer diagnosis and therapy. RSC Chem Biol 2022; 3:830-847. [PMID: 35866165 PMCID: PMC9257619 DOI: 10.1039/d2cb00094f] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 05/23/2022] [Indexed: 12/01/2022] Open
Abstract
Although antibodies are well developed and widely used in cancer therapy and diagnostic fields, some defects remain, such as poor tissue penetration, long in vivo metabolic retention, potential cytotoxicity, patent limitation, and high production cost. These issues have led scientists to explore and develop novel antibody alternatives. Protein scaffolds are small monomeric proteins with stable tertiary structures and mutable residues, which emerged in the 1990s. By combining robust gene engineering and phage display techniques, libraries with sufficient diversity could be established for target binding scaffold selection. Given the properties of small size, high affinity, and excellent specificity and stability, protein scaffolds have been applied in basic research, and preclinical and clinical fields over the past two decades. To date, more than 20 types of protein scaffolds have been developed, with the most frequently used being affibody, adnectin, ANTICALIN®, DARPins, and knottin. In this review, we focus on the protein scaffold applications in cancer therapy and diagnosis in the last 5 years, and discuss the pros and cons, and strategies of optimization and design. Although antibodies are well developed and widely used in cancer therapy and diagnostic fields, some defects remain, such as poor tissue penetration, long in vivo metabolic retention, potential cytotoxicity, patent limitation, and high production cost.![]()
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Affiliation(s)
- Renli Luo
- Department of Molecular Medicine, College of Life and Health Sciences, Northeastern University Shenyang China
| | - Hongguang Liu
- Department of Molecular Medicine, College of Life and Health Sciences, Northeastern University Shenyang China
| | - Zhen Cheng
- State Key Laboratory of Drug Research, Molecular Imaging Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences Shanghai 201203 China
- Drug Discovery Shandong Laboratory, Bohai Rim Advanced Research Institute for Drug Discovery Yantai Shandong 264117 China
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5
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Checco JW, Eddinger GA, Rettko NJ, Chartier AR, Gellman SH. Tumor Necrosis Factor-α Trimer Disassembly and Inactivation via Peptide-Small Molecule Synergy. ACS Chem Biol 2020; 15:2116-2124. [PMID: 32662976 DOI: 10.1021/acschembio.0c00313] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Aberrant signaling by tumor necrosis factor-α (TNFα) is associated with inflammatory diseases that can be treated with engineered proteins that inhibit binding of this cytokine to cell-surface receptors. Despite these clinical successes, there is considerable interest in the development of smaller antagonists of TNFα-receptor interactions. We describe a new 29-residue α/β-peptide, a molecule that contains three β-amino acid residues and three α-aminoisobutryic acid (Aib) residues, that displays potent inhibition of TNFα binding to TNFα receptor 1 (TNFR1) and rescues cells from TNFα-induced death. The complement of nonproteinogenic residues renders this α/β-peptide highly resistant to proteolysis, relative to all-α analogues. The mechanism of inhibitory action of the new 29-mer involves disruption of the trimeric TNFα quaternary structure, which prevents productive binding to TNFα receptors. Unexpectedly, we discovered that peptide-induced trimer disruption can be promoted by structurally diverse small molecules, including a detergent commonly used during selection procedures. The discovery of this synergistic effect provides a new context for understanding previous reports on peptidic antagonists of TNFα-receptor interactions and suggests new avenues for future efforts to block signaling via proteins with an active form that is oligomeric, including other members of the TNFα family.
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Affiliation(s)
- James W. Checco
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin, United States
| | - Geoffrey A. Eddinger
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin, United States
| | - Nicholas J. Rettko
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin, United States
| | - Alexander R. Chartier
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin, United States
| | - Samuel H. Gellman
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin, United States
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Qi S, Hoppmann S, Xu Y, Cheng Z. PET Imaging of HER2-Positive Tumors with Cu-64-Labeled Affibody Molecules. Mol Imaging Biol 2020; 21:907-916. [PMID: 30617730 DOI: 10.1007/s11307-018-01310-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
PURPOSE Previous studies has demonstrated the utility of human epidermal growth factor receptor type 2 (HER2) as an attractive target for cancer molecular imaging and therapy. An affibody protein with strong binding affinity for HER2, ZHER2:342, has been reported. Various methods of chelator conjugation for radiolabeling HER2 affibody molecules have been described in the literature including N-terminal conjugation, C-terminal conjugation, and other methods. Cu-64 has recently been extensively evaluated due to its half-life, decay properties, and availability. Our goal was to optimize the radiolabeling method of this affibody molecule with Cu-64, and translate a positron emission tomography (PET) probe with the best in vivo performance to clinical PET imaging of HER2-positive cancers. PROCEDURES In our study, three anti-HER2 affibody proteins-based PET probes were prepared, and their in vivo performance was evaluated in mice bearing HER2-positive subcutaneous SKOV3 tumors. The affibody analogues, Ac-Cys-ZHER2:342, Ac-ZHER2:342(Cys39), and Ac-ZHER2:342-Cys, were synthesized using the solid phase peptide synthesis method. The purified small proteins were site-specifically conjugated with the maleimide-functionalized chelator, 1,4,7,10-tetraazacyclododecane-1,4,7-tris- aceticacid-10-maleimidethylacetamide (maleimido-mono-amide-DOTA). The resulting DOTA-affibody conjugates were then radiolabeled with Cu-64. Cell uptake assay of the resulting PET probes, [64Cu]DOTA-Cys-ZHER2:342, [64Cu]DOTA-ZHER2:342(Cys39), and [64Cu]DOTA-ZHER2:342-Cys, was performed in HER2-positive human ovarian SKOV3 carcinoma cells at 4 and 37 °C. The binding affinities of the radiolabeled peptides were tested by cell saturation assay using SKOV3 cells. PET imaging, biodistribution, and metabolic stability studies were performed in mice bearing SKOV3 tumors. RESULTS Cell uptake assays showed high and specific uptake by incubation of Cu-64-labeled affibodies with SKOV3 cells. The affinities (KD) of the PET radio probes as tested by cell saturation analysis were in the low nanomolar range with the ranking of [64Cu]DOTA-Cys-ZHER2:342 (25.2 ± 9.2 nM) ≈ [64Cu]DOTA-ZHER2:342-Cys (32.6 ± 14.7 nM) > [64Cu]DOTA-ZHER2:342(Cys39) (77.6 ± 22.2 nM). In vitro stability and in vivo metabolite analysis study revealed that all three probes were stable enough for in vivo imaging applications, while [64Cu]DOTA-Cys-ZHER2:342 showed the highest stability. In vivo small-animal PET further demonstrated fast tumor targeting, good tumor accumulation, and good tumor to normal tissue contrast of all three probes. For [64Cu]DOTA-Cys-ZHER2:342, [64Cu]DOTA-ZHER2:342(Cys39), and [64Cu]DOTA-ZHER2:342-Cys, tumor uptake at 24 h are 4.0 ± 1.0 % ID/g, 4.0 ± 0.8 %ID/g, and 4.3 ± 0.7 %ID/g, respectively (mean ± SD, n = 4). Co-injection of the probes with non-labeled anti-HER2 affibody proteins confirmed in vivo specificities of the compounds by tumor uptake reduction. CONCLUSIONS The three Cu-64-labeled ZHER2:342 analogues all display excellent HER2 targeting ability and tumor PET imaging quality. Although varied in the position of the radiometal labeling of these three Cu-64-labeled ZHER2:342 analogues, there is no significant difference in tumor and normal tissue uptakes among the three probes. [64Cu]DOTA-Cys-ZHER2:342 stands out as the most superior PET probe because of its highest affinities and in vivo stability.
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Affiliation(s)
- Shibo Qi
- School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin, 300387, China.,Molecular Imaging Program at Stanford (MIPS), Department of Radiology, and Bio-X Program, Canary Center at Stanford for Cancer Early Detection, Stanford University, Stanford, CA, 94305-5344, USA
| | - Susan Hoppmann
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology, and Bio-X Program, Canary Center at Stanford for Cancer Early Detection, Stanford University, Stanford, CA, 94305-5344, USA
| | - Yingding Xu
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology, and Bio-X Program, Canary Center at Stanford for Cancer Early Detection, Stanford University, Stanford, CA, 94305-5344, USA
| | - Zhen Cheng
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology, and Bio-X Program, Canary Center at Stanford for Cancer Early Detection, Stanford University, Stanford, CA, 94305-5344, USA.
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7
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Checco JW, Gellman SH. Iterative Nonproteinogenic Residue Incorporation Yields α/β-Peptides with a Helix-Loop-Helix Tertiary Structure and High Affinity for VEGF. Chembiochem 2017; 18:291-299. [PMID: 27897370 DOI: 10.1002/cbic.201600545] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Indexed: 12/12/2022]
Abstract
Inhibition of specific protein-protein interactions is attractive for a range of therapeutic applications, but the large and irregularly shaped contact surfaces involved in many such interactions make it challenging to design synthetic antagonists. Here, we describe the development of backbone-modified peptides containing both α- and β-amino acid residues (α/β-peptides) that target the receptor-binding surface of vascular endothelial growth factor (VEGF). Our approach is based on the Z-domain, which adopts a three-helix bundle tertiary structure. We show how a two-helix "mini-Z-domain" can be modified to contain β and other nonproteinogenic residues while retaining the target-binding epitope by using iterative unnatural residue incorporation. The resulting α/β-peptides are less susceptible to proteolysis than is their parent α-peptide, and some of these α/β-peptides match the full-length Z-domain in terms of affinity for receptor-recognition surfaces on the VEGF homodimer.
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Affiliation(s)
- James W Checco
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706, USA
| | - Samuel H Gellman
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706, USA
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Ding H, Gangalum PR, Galstyan A, Fox I, Patil R, Hubbard P, Murali R, Ljubimova JY, Holler E. HER2-positive breast cancer targeting and treatment by a peptide-conjugated mini nanodrug. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2016; 13:631-639. [PMID: 27520726 DOI: 10.1016/j.nano.2016.07.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 11/17/2022]
Abstract
HER2+ breast cancer is one of the most aggressive forms of breast cancer. The new polymalic acid-based mini nanodrug copolymers are synthesized and specifically characterized to inhibit growth of HER2+ breast cancer. These mini nanodrugs are highly effective and in the clinic may substitute for trastuzumab (the marketed therapeutic antibody) and antibody-targeted nanobioconjugates. Novel mini nanodrugs are designed to have slender shape and small size. HER2+ cells were recognized by the polymer-attached trastuzumab-mimetic 12-mer peptide. Synthesis of the nascent cell-transmembrane HER2/neu receptors by HER2+ cells was inhibited by antisense oligonucleotides that prevented cancer cell proliferation and significantly reduced tumor size by more than 15 times vs. untreated control or PBS-treated group. We emphasize that the shape and size of mini nanodrugs can enhance penetration of multiple bio-barriers to facilitate highly effective treatment. Replacement of trastuzumab by the mimetic peptide favors reduced production costs and technical efforts, and a negligible immune response.
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Affiliation(s)
- Hui Ding
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Pallavi R Gangalum
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Anna Galstyan
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Irving Fox
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Rameshwar Patil
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Paul Hubbard
- Department of Biomedical Sciences, Research Division of Immunology, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Ramachandran Murali
- Department of Biomedical Sciences, Research Division of Immunology, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Julia Y Ljubimova
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Eggehard Holler
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, United States.
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Zhao N, Liu S, Jiang Q, Lan T, Cheng Z, Liu H. Small-Protein-Stabilized Semiconductor Nanoprobe for Targeted Imaging of Cancer Cells. Chembiochem 2016; 17:1202-6. [DOI: 10.1002/cbic.201600219] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Ning Zhao
- Institute of Molecular Medicine; College of Life and Health Sciences; Northeastern University; 195 Chuangxin Road Shenyang 110000 China
| | - Siyu Liu
- Institute of Molecular Medicine; College of Life and Health Sciences; Northeastern University; 195 Chuangxin Road Shenyang 110000 China
| | - Qike Jiang
- Dalian Institute of Chemical Physics; Chinese Academy of Sciences; 457 Zhongshan Road Dalian 116023 China
| | - Tian Lan
- Institute of Molecular Medicine; College of Life and Health Sciences; Northeastern University; 195 Chuangxin Road Shenyang 110000 China
| | - Zhen Cheng
- Molecular Imaging Program at Stanford; Department of Radiology; Stanford University; 1201 Welch Road Stanford CA 94040 USA
| | - Hongguang Liu
- Institute of Molecular Medicine; College of Life and Health Sciences; Northeastern University; 195 Chuangxin Road Shenyang 110000 China
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Targeting diverse protein-protein interaction interfaces with α/β-peptides derived from the Z-domain scaffold. Proc Natl Acad Sci U S A 2015; 112:4552-7. [PMID: 25825775 DOI: 10.1073/pnas.1420380112] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Peptide-based agents derived from well-defined scaffolds offer an alternative to antibodies for selective and high-affinity recognition of large and topologically complex protein surfaces. Here, we describe a strategy for designing oligomers containing both α- and β-amino acid residues ("α/β-peptides") that mimic several peptides derived from the three-helix bundle "Z-domain" scaffold. We show that α/β-peptides derived from a Z-domain peptide targeting vascular endothelial growth factor (VEGF) can structurally and functionally mimic the binding surface of the parent peptide while exhibiting significantly decreased susceptibility to proteolysis. The tightest VEGF-binding α/β-peptide inhibits the VEGF165-induced proliferation of human umbilical vein endothelial cells. We demonstrate the versatility of this strategy by showing how principles underlying VEGF signaling inhibitors can be rapidly extended to produce Z-domain-mimetic α/β-peptides that bind to two other protein partners, IgG and tumor necrosis factor-α. Because well-established selection techniques can identify high-affinity Z-domain derivatives from large DNA-encoded libraries, our findings should enable the design of biostable α/β-peptides that bind tightly and specifically to diverse targets of biomedical interest. Such reagents would be useful for diagnostic and therapeutic applications.
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Su X, Cheng K, Jeon J, Shen B, Venturin GT, Hu X, Rao J, Chin FT, Wu H, Cheng Z. Comparison of two site-specifically (18)F-labeled affibodies for PET imaging of EGFR positive tumors. Mol Pharm 2014; 11:3947-56. [PMID: 24972326 PMCID: PMC4218868 DOI: 10.1021/mp5003043] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
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The
epidermal growth factor receptor (EGFR) serves as an attractive target
for cancer molecular imaging and therapy. Our previous positron emission
tomography (PET) studies showed that the EGFR-targeting affibody molecules 64Cu-DOTA-ZEGFR:1907 and 18F-FBEM-ZEGFR:1907 can discriminate between high and low EGFR-expression
tumors and have the potential for patient selection for EGFR-targeted
therapy. Compared with 64Cu, 18F may improve
imaging of EGFR-expression and is more suitable for clinical application,
but the labeling reaction of 18F-FBEM-ZEGFR:1907 requires a long synthesis time. The aim of the present study is
to develop a new generation of 18F labeled affibody probes
(Al18F-NOTA-ZEGFR:1907 and 18F-CBT-ZEGFR:1907) and to determine whether they are suitable agents
for imaging of EGFR expression. The first approach consisted of conjugating
ZEGFR:1907 with NOTA and radiolabeling with Al18F to produce Al18F-NOTA-ZEGFR:1907. In a second
approach the prosthetic group 18F-labeled-2-cyanobenzothiazole
(18F-CBT) was conjugated to Cys-ZEGFR:1907 to
produce 18F-CBT-ZEGFR:1907. Binding affinity
and specificity of Al18F-NOTA-ZEGFR:1907 and 18F-CBT-ZEGFR:1907 to EGFR were evaluated using
A431 cells. Biodistribution and PET studies were conducted on mice
bearing A431 xenografts after injection of Al18F-NOTA-ZEGFR:1907 or 18F-CBT-ZEGFR:1907 with
or without coinjection of unlabeled affibody proteins. The radiosyntheses
of Al18F-NOTA-ZEGFR:1907 and 18F-CBT-ZEGFR:1907 were completed successfully within 40 and 120 min
with a decay-corrected yield of 15% and 41% using a 2-step, 1-pot
reaction and 2-step, 2-pot reaction, respectively. Both probes bound
to EGFR with low nanomolar affinity in A431 cells. Although 18F-CBT-ZEGFR:1907 showed instability in vivo, biodistribution studies revealed rapid and high tumor accumulation
and quick clearance from normal tissues except the bones. In contrast,
Al18F-NOTA-ZEGFR:1907 demonstrated high in vitro and in vivo stability, high tumor
uptake, and relative low uptake in most of the normal organs except
the liver and kidneys at 3 h after injection. The specificity of both
probes for A431 tumors was confirmed by their lower uptake on coinjection
of unlabeled affibody. PET studies showed that Al18F-NOTA-ZEGFR:1907 and 18F-CBT-ZEGFR:1907 could
clearly identify EGFR positive tumors with good contrast. Two strategies
for 18F-labeling of affibody molecules were successfully
developed as two model platforms using NOTA or CBT coupling to affibody
molecules that contain an N-terminal cysteine. Al18F-NOTA-ZEGFR:1907 and 18F-CBT-ZEGFR:1907 can
be reliably obtained in a relatively short time. Biodistribution and
PET studies demonstrated that Al18F-NOTA-ZEGFR:1907 is a promising PET probe for imaging EGFR expression in living mice.
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Affiliation(s)
- Xinhui Su
- Department of Nuclear Medicine, Zhongshan Hospital Xiamen University , Xiamen 361004, China
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Stern LA, Case BA, Hackel BJ. Alternative Non-Antibody Protein Scaffolds for Molecular Imaging of Cancer. Curr Opin Chem Eng 2013; 2. [PMID: 24358455 DOI: 10.1016/j.coche.2013.08.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The development of improved methods for early detection and characterization of cancer presents a major clinical challenge. One approach that has shown excellent potential in preclinical and clinical evaluation is molecular imaging with small-scaffold, non-antibody based, engineered proteins. These novel diagnostic agents produce high contrast images due to their fast clearance from the bloodstream and healthy tissues, can be evolved to bind a multitude of cancer biomarkers, and are easily functionalized by site-specific bioconjugation methods. Several small protein scaffolds have been verified for in vivo molecular imaging including affibodies and their two-helix variants, knottins, fibronectins, DARPins, and several natural ligands. Further, the biodistribution of these engineered ligands can be optimized through rational mutation of the conserved regions, careful selection and placement of chelator, and modification of molecular size.
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Affiliation(s)
- Lawrence A Stern
- Department of Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Minneapolis, MN 55455
| | - Brett A Case
- Department of Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Minneapolis, MN 55455
| | - Benjamin J Hackel
- Department of Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Minneapolis, MN 55455
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Abstract
In an effort to discover a noninvasive method for predicting which cancer patients will benefit from therapy targeting the EGFR and HER2 proteins, a large body of the research has been conducted toward the development of PET and SPECT imaging agents, which selectively target these receptors. We provide a general overview of the advances made toward imaging EGFR and HER2, detailing the investigation of PET and SPECT imaging agents ranging in size from small molecules to monoclonal antibodies.
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Affiliation(s)
- Emily B Corcoran
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts
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Honarvar H, Jokilaakso N, Andersson K, Malmberg J, Rosik D, Orlova A, Karlström AE, Tolmachev V, Järver P. Evaluation of backbone-cyclized HER2-binding 2-helix Affibody molecule for In Vivo molecular imaging. Nucl Med Biol 2013; 40:378-86. [DOI: 10.1016/j.nucmedbio.2012.12.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 12/13/2012] [Accepted: 12/17/2012] [Indexed: 01/22/2023]
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Ren G, Webster JM, Liu Z, Zhang R, Miao Z, Liu H, Gambhir SS, Syud FA, Cheng Z. In vivo targeting of HER2-positive tumor using 2-helix affibody molecules. Amino Acids 2012; 43:405-13. [PMID: 21984380 PMCID: PMC4172459 DOI: 10.1007/s00726-011-1096-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022]
Abstract
Molecular imaging of human epidermal growth factor receptor type 2 (HER2) expression has drawn significant attention because of the unique role of the HER2 gene in diagnosis, therapy and prognosis of human breast cancer. In our previous research, a novel cyclic 2-helix small protein, MUT-DS, was discovered as an anti-HER2 Affibody analog with high affinity through rational protein design and engineering. MUT-DS was then evaluated for positron emission tomography (PET) of HER2-positive tumor by labeling with two radionuclides, 68Ga and 18F, with relatively short half-life (t1/2<2 h). In order to fully study the in vivo behavior of 2-helix small protein and demonstrate that it could be a robust platform for labeling with a variety of radionuclides for different applications, in this study, MUT-DS was further radiolabeled with 64Cu or 111In and evaluated for in vivo targeting of HER2-positive tumor in mice. Design 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugated MUT-DS (DOTA-MUT-DS) was chemically synthesized using solid phase peptide synthesizer and I2 oxidation. DOTA-MUT-DS was then radiolabeled with 64Cu or 111In to prepare the HER2 imaging probe (64Cu/111In-DOTA-MUT-DS). Both biodistribution and microPET imaging of the probe were evaluated in nude mice bearing subcutaneous HER2-positive SKOV3 tumors. DOTA-MUT-DS could be successfully synthesized and radiolabeled with 64Cu or 111In. Biodistribution study showed that tumor uptake value of 64Cu or 111In-labeled DOTA-MUT-DS was 4.66±0.38 or 2.17±0.15%ID/g, respectively, in nude mice bearing SKOV3 xenografts (n=3) at 1 h post-injection (p.i.). Tumor-to-blood and tumor-to-muscle ratios for 64Cu-DOTA-MUT-DS were attained to be 3.05 and 3.48 at 1 h p.i., respectively, while for 111In-DOTA-MUT-DS, they were 2.04 and 3.19, respectively. Co-injection of the cold Affibody molecule ZHER2:342 with 64Cu-DOTA-MUT-DS specifically reduced the SKOV3 tumor uptake of the probe by 48%. 111In-DOTA-MUT-DS displayed lower liver uptake at all the time points investigated and higher tumor to blood ratios at 4 and 20 h p.i., when compared with 64Cu-DOTA-MUT-DS. This study demonstrates that the 2-helix protein based probes, 64Cu/111In DOTA-MUT-DS, are promising molecular probes for imaging HER2-positive tumor. Two-helix small protein scaffold holds great promise as a novel and robust platform for imaging and therapy applications.
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Affiliation(s)
- Gang Ren
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University, California, Stanford, CA 94305-5344, USA
| | - Jack M. Webster
- General Electric Company, Global Research Center, Niskayuna, NY 12309, USA
| | - Zhe Liu
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University, California, Stanford, CA 94305-5344, USA
| | - Rong Zhang
- General Electric Company, Global Research Center, Niskayuna, NY 12309, USA
| | - Zheng Miao
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University, California, Stanford, CA 94305-5344, USA
| | - Hongguang Liu
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University, California, Stanford, CA 94305-5344, USA
| | - Sanjiv S. Gambhir
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University, California, Stanford, CA 94305-5344, USA
| | - Faisal A. Syud
- General Electric Company, Global Research Center, Niskayuna, NY 12309, USA
| | - Zhen Cheng
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University, California, Stanford, CA 94305-5344, USA
- Molecular Imaging Program at Stanford, Departments of Radiology, Stanford University, 1201 Welch Road, Lucas Expansion, P020A, Stanford, CA 94305, USA
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Direct comparison of 111In-labelled two-helix and three-helix Affibody molecules for in vivo molecular imaging. Eur J Nucl Med Mol Imaging 2011; 39:693-702. [DOI: 10.1007/s00259-011-2016-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 11/22/2011] [Indexed: 02/08/2023]
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PET imaging of HER-2-positive tumours. Eur J Nucl Med Mol Imaging 2011; 38:1961-3. [DOI: 10.1007/s00259-011-1933-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Miao Z, Levi J, Cheng Z. Protein scaffold-based molecular probes for cancer molecular imaging. Amino Acids 2011; 41:1037-47. [PMID: 20174842 PMCID: PMC2914822 DOI: 10.1007/s00726-010-0503-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Accepted: 01/25/2010] [Indexed: 01/18/2023]
Abstract
Protein scaffold molecules are powerful reagents for targeting various cell signal receptors, enzymes, cytokines and other cancer-related molecules. They belong to the peptide and small protein platform with distinct properties. For the purpose of development of new generation molecular probes, various protein scaffold molecules have been labeled with imaging moieties and evaluated both in vitro and in vivo. Among the evaluated probes Affibody molecules and analogs, cystine knot peptides, and nanobodies have shown especially good characteristics as protein scaffold platforms for development of in vivo molecular probes. Quantitative data obtained from positron emission tomography, single photon emission computed tomography/CT, and optical imaging together with biodistribution studies have shown high tumor uptakes and high tumor-to-blood ratios for these probes. High tumor contrast imaging has been obtained within 1 h after injection. The success of those molecular probes demonstrates the adequacy of protein scaffold strategy as a general approach in molecular probe development.
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Affiliation(s)
- Zheng Miao
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University, CA 94305-5344, USA
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A novel 18F-labeled two-helix scaffold protein for PET imaging of HER2-positive tumor. Eur J Nucl Med Mol Imaging 2011; 38:1977-84. [PMID: 21761266 DOI: 10.1007/s00259-011-1879-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 06/28/2011] [Indexed: 01/17/2023]
Abstract
PURPOSE Two-helix scaffold proteins (~ 5 kDa) against human epidermal growth factor receptor type 2 (HER2) have been discovered in our previous work. In this research we aimed to develop an (18)F-labeled two-helix scaffold protein for positron emission tomography (PET) imaging of HER2-positive tumors. METHODS An aminooxy-functionalized two-helix peptide (AO-MUT-DS) with high HER2 binding affinity was synthesized through conventional solid phase peptide synthesis. The purified linear peptide was cyclized by I(2) oxidation to form a disulfide bridge. The cyclic peptide was then conjugated with a radiofluorination synthon, 4-(18)F-fluorobenzyl aldehyde ((18)F-FBA), through the aminooxy functional group at the peptide N terminus (30% yield, non-decay corrected). The binding affinities of the peptides were analyzed by Biacore analysis. Cell uptake assay of the resulting PET probe, (18)F-FBO-MUT-DS, was performed at 37°C. (18)F-FBO-MUT-DS with high specific activity (20-32 MBq/nmol, 88-140 μCi/μg, end of synthesis) was injected into mice xenograft model bearing SKOV3 tumor. MicroPET and biodistribution and metabolic stability studies were then conducted. RESULTS Cell uptake assays showed high and specific cell uptake (~12% applied activity at 1 h) by incubation of (18)F-FBO-MUT-DS with HER2 high-expressing SKOV3 ovarian cancer cells. The affinities (K(D)) of AO-MUT-DS and FBO-MUT-DS as tested by Biacore analysis were 2 and 1 nM, respectively. In vivo small animal PET demonstrated fast tumor targeting, high tumor accumulation, and good tumor to normal tissue contrast of (18)F-FBO-MUT-DS. Biodistribution studies further revealed that the probe had excellent tumor uptake (6.9%ID/g at 1 h post-injection) and was cleared through both liver and kidneys. Co-injection of the probe with 500 μg of HER2 Affibody protein reduced the tumor uptake (6.9 vs 1.8%ID/g, p < 0.05). CONCLUSION F-FBO-MUT-DS displays excellent HER2 targeting ability and tumor PET imaging quality. The two-helix scaffold proteins are suitable for development of (18)F-based PET probes.
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Cochran R, Cochran F. Phage display and molecular imaging: expanding fields of vision in living subjects. Biotechnol Genet Eng Rev 2011; 27:57-94. [PMID: 21415893 DOI: 10.1080/02648725.2010.10648145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In vivo molecular imaging enables non-invasive visualization of biological processes within living subjects, and holds great promise for diagnosis and monitoring of disease. The ability to create new agents that bind to molecular targets and deliver imaging probes to desired locations in the body is critically important to further advance this field. To address this need, phage display, an established technology for the discovery and development of novel binding agents, is increasingly becoming a key component of many molecular imaging research programs. This review discusses the expanding role played by phage display in the field of molecular imaging with a focus on in vivo applications. Furthermore, new methodological advances in phage display that can be directly applied to the discovery and development of molecular imaging agents are described. Various phage library selection strategies are summarized and compared, including selections against purified target, intact cells, and ex vivo tissue, plus in vivo homing strategies. An outline of the process for converting polypeptides obtained from phage display library selections into successful in vivo imaging agents is provided, including strategies to optimize in vivo performance. Additionally, the use of phage particles as imaging agents is also described. In the latter part of the review, a survey of phage-derived in vivo imaging agents is presented, and important recent examples are highlighted. Other imaging applications are also discussed, such as the development of peptide tags for site-specific protein labeling and the use of phage as delivery agents for reporter genes. The review concludes with a discussion of how phage display technology will continue to impact both basic science and clinical applications in the field of molecular imaging.
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Affiliation(s)
- R Cochran
- Department of Bioengineering, Cancer Center, Bio-X Program, Stanford University, Stanford CA, USA
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Jokerst JV, Miao Z, Zavaleta C, Cheng Z, Gambhir SS. Affibody-functionalized gold-silica nanoparticles for Raman molecular imaging of the epidermal growth factor receptor. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2011; 7:625-33. [PMID: 21302357 PMCID: PMC3386295 DOI: 10.1002/smll.201002291] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Indexed: 05/17/2023]
Abstract
The affibody functionalization of fluorescent surface-enhanced Raman scattering gold-silica nanoparticles as multimodal contrast agents for molecular imaging specific to epidermal growth factor receptor (EGFR) is reported. This nanoparticle bioconjugate reports EGFR-positive A431 tumors with a signal nearly 35-fold higher than EGFR-negative MDA-435S tumors. The low-level EGFR expression in adjacent healthy tissue is 7-fold lower than in the positive tumors. Validation via competitive inhibition reduces the signal by a factor of six, and independent measurement of EGFR via flow cytometry correlates at R(2) = 0.92.
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Affiliation(s)
- Jesse V. Jokerst
- Molecular Imaging Program at Stanford, Department of Radiology, Department of Bioengineering, Materials Science and Engineering and Bio-X, 318 Campus Drive, Stanford, CA 94305, USA
| | - Zheng Miao
- Molecular Imaging Program at Stanford, Department of Radiology, Department of Bioengineering, Materials Science and Engineering and Bio-X, 318 Campus Drive, Stanford, CA 94305, USA
| | - Cristina Zavaleta
- Molecular Imaging Program at Stanford, Department of Radiology, Department of Bioengineering, Materials Science and Engineering and Bio-X, 318 Campus Drive, Stanford, CA 94305, USA
| | - Zhen Cheng
- Molecular Imaging Program at Stanford, Department of Radiology, Department of Bioengineering, Materials Science and Engineering and Bio-X, 318 Campus Drive, Stanford, CA 94305, USA
| | - Sanjiv S. Gambhir
- Molecular Imaging Program at Stanford, Department of Radiology, Department of Bioengineering, Materials Science and Engineering and Bio-X, 318 Campus Drive, Stanford, CA 94305, USA
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Chen K, Chen X. Design and development of molecular imaging probes. Curr Top Med Chem 2011; 10:1227-36. [PMID: 20388106 DOI: 10.2174/156802610791384225] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Accepted: 02/27/2010] [Indexed: 01/17/2023]
Abstract
Molecular imaging, the visualization, characterization and measurement of biological processes at the cellular, subcellular level, or even molecular level in living subjects, has rapidly gained importance in the dawning era of personalized medicine. Molecular imaging takes advantage of the traditional diagnostic imaging techniques and introduces molecular imaging probes to determine the expression of indicative molecular markers at different stages of diseases and disorders. As a key component of molecular imaging, molecular imaging probe must be able to specifically reach the target of interest in vivo while retaining long enough to be detected. A desirable molecular imaging probe with clinical translation potential is expected to have unique characteristics. Therefore, design and development of molecular imaging probe is frequently a challenging endeavor for medicinal chemists. This review summarizes the general principles of molecular imaging probe design and some fundamental strategies of molecular imaging probe development with a number of illustrative examples.
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Affiliation(s)
- Kai Chen
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA.
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Aw J, Shao Q, Yang Y, Jiang T, Ang C, Xing B. Synthesis and characterization of 2-(2'-hydroxy-5'-chlorophenyl)-6-chloro-4(3H)-quinazolinone-based fluorogenic probes for cellular imaging of monoamine oxidases. Chem Asian J 2010; 5:1317-21. [PMID: 20397188 DOI: 10.1002/asia.201000025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Junxin Aw
- Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
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Löfblom J, Feldwisch J, Tolmachev V, Carlsson J, Ståhl S, Frejd F. Affibody molecules: Engineered proteins for therapeutic, diagnostic and biotechnological applications. FEBS Lett 2010; 584:2670-80. [DOI: 10.1016/j.febslet.2010.04.014] [Citation(s) in RCA: 406] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 04/06/2010] [Accepted: 04/08/2010] [Indexed: 01/28/2023]
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A HER2-binding Affibody molecule labelled with 68Ga for PET imaging: direct in vivo comparison with the 111In-labelled analogue. Eur J Nucl Med Mol Imaging 2010; 37:1356-67. [DOI: 10.1007/s00259-009-1367-7] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 12/14/2009] [Indexed: 12/31/2022]
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Abstract
LL-37 is a human host defence peptide that has a wide range of biological functions, including antimicrobial and immunomodulatory properties. This review summarises how molecular structure influences the balance between the immunomodulatory and antimicrobial functions of LL-37.
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Affiliation(s)
- Matthew F Burton
- Centre for Bioactive Chemistry, Department of Chemistry, University of Durham, Science Laboratory, South Road, Durham, DH1 3LE, UK.
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Ren G, Zhang R, Liu Z, Webster JM, Miao Z, Gambhir SS, Syud FA, Cheng Z. A 2-helix small protein labeled with 68Ga for PET imaging of HER2 expression. J Nucl Med 2009; 50:1492-9. [PMID: 19690041 DOI: 10.2967/jnumed.109.064287] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
UNLABELLED Affibody molecules are a class of scaffold proteins being developed into a generalizable approach to targeting tumors. Many 3-helix-based Affibody proteins have shown excellent in vivo properties for tumor imaging and therapy. By truncating one alpha-helix that is not responsible for receptor recognition in the Affibody and maturating the protein affinity through synthetic strategies, we have successfully identified in our previous research several small 2-helix proteins with excellent binding affinities to human epidermal growth factor receptor type 2 (HER2). With preferential properties such as faster blood clearance and tumor accumulation, lower immunogenic potential, and facile and economically viable synthetic schemes, we hypothesized that these 2-helix protein binders could become excellent molecular imaging probes for monitoring HER2 expression and modulation. METHODS In this study, a 2-helix small protein, MUT-DS, was chemically modified with a metal chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). DOTA-MUT-DS was then site-specifically radiolabeled with an important PET radionuclide, (68)Ga. The resulting radiolabeled anti-HER2 2-helix molecule was further evaluated as a potential molecular probe for small-animal PET HER2 imaging in a SKOV3 tumor mouse model. RESULTS The 2-helix DOTA-MUT-DS showed high HER2-binding affinity (dissociation constant, 4.76 nM). The radiolabeled probe displayed high stability in mouse serum and specificity toward HER2 in cell cultures. Biodistribution and small-animal PET studies further showed that (68)Ga-DOTA-MUT-DS had rapid and high SKOV3 tumor accumulation and quick clearance from normal organs. The specificity of (68)Ga-DOTA-MUT-DS for SKOV3 tumors was confirmed by monitoring modulation of HER2 protein on treatment of tumor mice with heat shock protein 90 inhibitor 17-N,N-dimethyl ethylene diamine-geldanamycin in vivo. CONCLUSION This proof-of-concept research clearly demonstrated that synthetic 2-helix (68)Ga-DOTA-MUT-DS is a promising PET probe for imaging HER2 expression in vivo. The Affibody-derived small 2-helix protein scaffold has great potential for developing targeting agents for a variety of tumor-associated biomarkers.
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Affiliation(s)
- Gang Ren
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University, Stanford, California, USA
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