1
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Ma X, Wang M, Ying T, Wu Y. Reforming solid tumor treatment: the emerging potential of smaller format antibody-drug conjugate. Antib Ther 2024; 7:114-122. [PMID: 38566971 PMCID: PMC10983081 DOI: 10.1093/abt/tbae005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/23/2024] [Accepted: 02/07/2024] [Indexed: 04/04/2024] Open
Abstract
In recent years, substantial therapeutic efficacy of antibody-drug conjugates (ADCs) has been validated through approvals of 16 ADCs for the treatment of malignant tumors. However, realization of the maximum clinical use of ADCs requires surmounting extant challenges, mainly the limitations in tumor penetration capabilities when targeting solid tumors. To resolve the hurdle of suboptimal tumor penetration, miniaturized antibody fragments with engineered formats have been harnessed for ADC assembly. By virtue of their reduced molecular sizes, antibody fragment-drug conjugates hold considerable promise for efficacious delivery of cytotoxic agents, thus conferring superior therapeutic outcomes. This review will focus on current advancements in novel ADC development utilizing smaller antibody formats from ~6 to 80 kDa, with particular emphasis on single-domain antibodies, which have been widely applied in novel ADC design. Additionally, strategies to optimize clinical translation are discussed, including half-life extension, acceleration of internalization, and reduction of immunogenic potential.
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Affiliation(s)
- Xiaojie Ma
- MOE/NHC/CAMS Key Laboratory of Medical Molecular Virology, Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Shanghai Institute of Infectious Disease and Biosecurity, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Mingkai Wang
- MOE/NHC/CAMS Key Laboratory of Medical Molecular Virology, Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Shanghai Institute of Infectious Disease and Biosecurity, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Tianlei Ying
- MOE/NHC/CAMS Key Laboratory of Medical Molecular Virology, Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Shanghai Institute of Infectious Disease and Biosecurity, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Shanghai Engineering Research Center for Synthetic Immunology, Fudan University, Shanghai 200032, China
| | - Yanling Wu
- MOE/NHC/CAMS Key Laboratory of Medical Molecular Virology, Shanghai Frontiers Science Center of Pathogenic Microorganisms and Infection, Shanghai Institute of Infectious Disease and Biosecurity, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Shanghai Engineering Research Center for Synthetic Immunology, Fudan University, Shanghai 200032, China
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2
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Liu L, Gray JL, Tate EW, Yang A. Bacterial enzymes: powerful tools for protein labeling, cell signaling, and therapeutic discovery. Trends Biotechnol 2023; 41:1385-1399. [PMID: 37328400 DOI: 10.1016/j.tibtech.2023.05.004] [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: 02/09/2023] [Revised: 05/01/2023] [Accepted: 05/16/2023] [Indexed: 06/18/2023]
Abstract
Bacteria have evolved a diverse set of enzymes that enable them to subvert host defense mechanisms as well as to form part of the prokaryotic immune system. Due to their unique and varied biochemical activities, these bacterial enzymes have emerged as key tools for understanding and investigating biological systems. In this review, we summarize and discuss some of the most prominent bacterial enzymes used for the site-specific modification of proteins, in vivo protein labeling, proximity labeling, interactome mapping, signaling pathway manipulation, and therapeutic discovery. Finally, we provide a perspective on the complementary advantages and limitations of using bacterial enzymes compared with chemical probes for exploring biological systems.
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Affiliation(s)
- Lu Liu
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Janine L Gray
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, UK
| | - Edward W Tate
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, UK.
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing 401331, China.
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3
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David TI, Pestov NB, Korneenko TV, Barlev NA. Non-Immunoglobulin Synthetic Binding Proteins for Oncology. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1232-1247. [PMID: 37770391 DOI: 10.1134/s0006297923090043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/01/2023] [Accepted: 08/01/2023] [Indexed: 09/30/2023]
Abstract
Extensive application of technologies like phage display in screening peptide and protein combinatorial libraries has not only facilitated creation of new recombinant antibodies but has also significantly enriched repertoire of the protein binders that have polypeptide scaffolds without homology to immunoglobulins. These innovative synthetic binding protein (SBP) platforms have grown in number and now encompass monobodies/adnectins, DARPins, lipocalins/anticalins, and a variety of miniproteins such as affibodies and knottins, among others. They serve as versatile modules for developing complex affinity tools that hold promise in both diagnostic and therapeutic settings. An optimal scaffold typically has low molecular weight, minimal immunogenicity, and demonstrates resistance against various challenging conditions, including proteolysis - making it potentially suitable for peroral administration. Retaining functionality under reducing intracellular milieu is also advantageous. However, paramount to its functionality is the scaffold's ability to tolerate mutations across numerous positions, allowing for the formation of a sufficiently large target binding region. This is achieved through the library construction, screening, and subsequent expression in an appropriate system. Scaffolds that exhibit high thermodynamic stability are especially coveted by the developers of new SBPs. These are steadily making their way into clinical settings, notably as antagonists of oncoproteins in signaling pathways. This review surveys the diverse landscape of SBPs, placing particular emphasis on the inhibitors targeting the oncoprotein KRAS, and highlights groundbreaking opportunities for SBPs in oncology.
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Affiliation(s)
- Temitope I David
- Institute of Biomedical Chemistry, Moscow, 119121, Russia
- Laboratory of Molecular Oncology, Phystech School of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Nikolay B Pestov
- Institute of Biomedical Chemistry, Moscow, 119121, Russia.
- Laboratory of Tick-Borne Encephalitis and Other Viral Encephalitides, Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products, Russian Academy of Sciences, Moscow, 108819, Russia
- Group of Cross-Linking Enzymes, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia
| | - Tatyana V Korneenko
- Group of Cross-Linking Enzymes, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia
| | - Nikolai A Barlev
- Institute of Biomedical Chemistry, Moscow, 119121, Russia
- Laboratory of Tick-Borne Encephalitis and Other Viral Encephalitides, Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products, Russian Academy of Sciences, Moscow, 108819, Russia
- Institute of Cytology Russian Academy of Sciences, St.-Petersburg, 194064, Russia
- School of Medicine, Nazarbayev University, Astana, 010000, Kazakhstan
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4
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Melo V, Nelemans LC, Vlaming M, Lourens HJ, Wiersma VR, Bilemjian V, Huls G, de Bruyn M, Bremer E. EGFR-selective activation of CD27 co-stimulatory signaling by a bispecific antibody enhances anti-tumor activity of T cells. Front Immunol 2023; 14:1191866. [PMID: 37545491 PMCID: PMC10399592 DOI: 10.3389/fimmu.2023.1191866] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 07/03/2023] [Indexed: 08/08/2023] Open
Abstract
A higher density of tumor infiltrating lymphocytes (TILs) in the tumor microenvironment, particularly cytotoxic CD8+ T cells, is associated with improved clinical outcome in various cancers. However, local inhibitory factors can suppress T cell activity and hinder anti-tumor immunity. Notably, TILs from various cancer types express the co-stimulatory Tumor Necrosis Factor receptor CD27, making it a potential target for co-stimulation and re-activation of tumor-infiltrated and tumor-reactive T cells. Anti-cancer therapeutics based on exploiting CD27-mediated T cell co-stimulation have proven safe, but clinical responses remain limited. This is likely because current monoclonal antibodies fail to effectively activate CD27 signaling, as this receptor requires higher-order receptor cross-linking. Here, we report on a bispecific antibody, CD27xEGFR, that targets both CD27 and the tumor antigen, epidermal growth factor receptor (EGFR). By targeting EGFR, which is commonly expressed on carcinomas, CD27xEGFR induced cancer cell-localized crosslinking and activation of CD27. The design of CD27xEGFR includes an Fc-silent domain, which is designed to minimize potential toxicity by reducing Fc gamma receptor-mediated binding and activation of immune cells. CD27xEGFR bound to both of its targets simultaneously and triggered EGFR-restricted co-stimulation of T cells as measured by T cell proliferation, T cell activation markers, cytotoxicity and IFN-γ release. Further, CD27xEGFR augmented T cell cytotoxicity in a panel of artificial antigen-presenting carcinoma cell line models, leading to Effector-to-Target ratio-dependent elimination of cancer cells. Taken together, we present the in vitro characterization of a novel bispecific antibody that re-activates T cell immunity in EGFR-expressing cancers through targeted co-stimulation of CD27.
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Affiliation(s)
- Vinicio Melo
- Department of Hematology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Levi Collin Nelemans
- Department of Hematology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Martijn Vlaming
- Department of Hematology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Harm Jan Lourens
- Department of Hematology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Valerie R. Wiersma
- Department of Hematology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Vrouyr Bilemjian
- Department of Hematology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Gerwin Huls
- Department of Hematology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Marco de Bruyn
- Department of Obstetrics & Gynecology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Edwin Bremer
- Department of Hematology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
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Gabriele F, Palerma M, Ippoliti R, Angelucci F, Pitari G, Ardini M. Recent Advances on Affibody- and DARPin-Conjugated Nanomaterials in Cancer Therapy. Int J Mol Sci 2023; 24:ijms24108680. [PMID: 37240041 DOI: 10.3390/ijms24108680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/06/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
Affibodies and designed ankyrin repeat proteins (DARPins) are synthetic proteins originally derived from the Staphylococcus aureus virulence factor protein A and the human ankyrin repeat proteins, respectively. The use of these molecules in healthcare has been recently proposed as they are endowed with biochemical and biophysical features heavily demanded to target and fight diseases, as they have a strong binding affinity, solubility, small size, multiple functionalization sites, biocompatibility, and are easy to produce; furthermore, impressive chemical and thermal stability can be achieved. especially when using affibodies. In this sense, several examples reporting on affibodies and DARPins conjugated to nanomaterials have been published, demonstrating their suitability and feasibility in nanomedicine for cancer therapy. This minireview provides a survey of the most recent studies describing affibody- and DARPin-conjugated zero-dimensional nanomaterials, including inorganic, organic, and biological nanoparticles, nanorods, quantum dots, liposomes, and protein- and DNA-based assemblies for targeted cancer therapy in vitro and in vivo.
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Affiliation(s)
- Federica Gabriele
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy
| | - Marta Palerma
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy
| | - Rodolfo Ippoliti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy
| | - Francesco Angelucci
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy
| | - Giuseppina Pitari
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy
| | - Matteo Ardini
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy
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6
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Cho H, Shim MK, Moon Y, Song S, Kim J, Choi J, Kim J, Lee Y, Park JY, Kim Y, Ahn CH, Kim MR, Yoon HY, Kim K. Tumor-Specific Monomethyl Auristatin E (MMAE) Prodrug Nanoparticles for Safe and Effective Chemotherapy. Pharmaceutics 2022; 14:pharmaceutics14102131. [PMID: 36297566 PMCID: PMC9609178 DOI: 10.3390/pharmaceutics14102131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/01/2022] [Accepted: 10/05/2022] [Indexed: 11/06/2022] Open
Abstract
A prodrug is bioreversible medication that is specifically converted to the active drugs by enzymes overexpressed in the tumor microenvironment, which can considerably reduce the chemotherapy-induced side effects. However, prodrug strategies usually have low antitumor efficacy compared to free drugs by delayed drug release. This is because they need time to be activated by enzymatic cleavage and they also cannot be fully recovered to the active drugs. Therefore, highly potent anticancer drug should be considered to expect a sufficient antitumor efficacy. Herein, we propose tumor-specific monomethyl auristatin E (MMAE) prodrug nanoparticles for safe and effective chemotherapy. The cathepsin B-specific cleavable FRRG peptide and MMAE are chemically conjugated via one-step simple synthetic chemistry. The resulting FRRG-MMAE molecules form stable nanoparticles without any additional carrier materials by hydrophobic interaction-derived aggregations. The FRRG-MMAE nanoparticles efficiently accumulate within the tumor tissues owing to the enhanced permeability and retention (EPR) effect and inhibit the tubulin polymerization by releasing free MMAE in the cathepsin B-overexpressed tumor cells. In contrast, FRRG-MMAE nanoparticles maintain a non-toxic inactive state in the normal tissues owing to innately low cathepsin B expression, thereby reducing MMAE-related severe toxicity. Collectively, this study provides a promising approach for safe and effective chemotherapy via MMAE-based prodrug nanoparticles, which may open new avenues for advanced drug design for translational nanomedicine.
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Affiliation(s)
- Hanhee Cho
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea
- Biomedical Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Man Kyu Shim
- Biomedical Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Yujeong Moon
- Biomedical Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Sukyung Song
- Biomedical Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Jinseong Kim
- Biomedical Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Jiwoong Choi
- Biomedical Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Jeongrae Kim
- Biomedical Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Youngjoo Lee
- Biomedical Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Jung Yeon Park
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Department of Integrative Energy Engineering, KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Yongju Kim
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Department of Integrative Energy Engineering, KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Cheol-Hee Ahn
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea
| | - Mi Ra Kim
- Department of Otorhinolaryngology-Head and Neck Surgery, Haeundae Paik Hospital, College of Medicine, Inje University, Busan 48108, Korea
| | - Hong Yeol Yoon
- Biomedical Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Kwangmeyung Kim
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul 03760, Korea
- Correspondence:
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7
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Garousi J, Xu T, Liu Y, Vorontsova O, Hober S, Orlova A, Tolmachev V, Gräslund T, Vorobyeva A. Experimental HER2-Targeted Therapy Using ADAPT6-ABD-mcDM1 in Mice Bearing SKOV3 Ovarian Cancer Xenografts: Efficacy and Selection of Companion Imaging Counterpart. Pharmaceutics 2022; 14:pharmaceutics14081612. [PMID: 36015242 PMCID: PMC9415843 DOI: 10.3390/pharmaceutics14081612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 02/01/2023] Open
Abstract
Overexpression of the human epidermal growth factor receptor 2 (HER2) in breast and gastric cancer is exploited for targeted therapy using monoclonal antibodies and antibody-drug conjugates. Small engineered scaffold proteins, such as the albumin binding domain (ABD) derived affinity proteins (ADAPTs), are a promising new format of targeting probes for development of drug conjugates with well-defined structure and tunable pharmacokinetics. Radiolabeled ADAPT6 has shown excellent tumor-targeting properties in clinical trials. Recently, we developed a drug conjugate based on the HER2-targeting ADAPT6 fused to an albumin binding domain (ABD) for increased bioavailability and conjugated to DM1 for cytotoxic action, designated as ADAPT6-ABD-mcDM1. In this study, we investigated the therapeutic efficacy of this conjugate in mice bearing HER2-expressing SKOV3 ovarian cancer xenografts. A secondary aim was to evaluate several formats of imaging probes for visualization of HER2 expression in tumors. Administration of ADAPT6-ABD-mcDM1 provided a significant delay of tumor growth and increased the median survival of the mice, in comparison with both a non-targeting homologous construct (ADAPTNeg-ABD-mcDM1) and the vehicle-treated groups, without inducing toxicity to liver or kidneys. Moreover, the evaluation of imaging probes showed that small scaffold proteins, such as 99mTc(CO)3-ADAPT6 or the affibody molecule 99mTc-ZHER2:41071, are well suited as diagnostic companions for potential stratification of patients for ADAPT6-ABD-mcDM1–based therapy.
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Affiliation(s)
- Javad Garousi
- Department of Protein Science, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden; (J.G.); (S.H.)
| | - Tianqi Xu
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85 Uppsala, Sweden; (T.X.); (Y.L.); (O.V.); (A.V.)
| | - Yongsheng Liu
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85 Uppsala, Sweden; (T.X.); (Y.L.); (O.V.); (A.V.)
| | - Olga Vorontsova
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85 Uppsala, Sweden; (T.X.); (Y.L.); (O.V.); (A.V.)
| | - Sophia Hober
- Department of Protein Science, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden; (J.G.); (S.H.)
| | - Anna Orlova
- Department of Medicinal Chemistry, Uppsala University, 751 23 Uppsala, Sweden;
| | - Vladimir Tolmachev
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85 Uppsala, Sweden; (T.X.); (Y.L.); (O.V.); (A.V.)
- Correspondence: (V.T.); (T.G.); Tel.: +46-70-425-07-82 (V.T.); +46-(0)8-790-96-27 (T.G.)
| | - Torbjörn Gräslund
- Department of Protein Science, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden; (J.G.); (S.H.)
- Correspondence: (V.T.); (T.G.); Tel.: +46-70-425-07-82 (V.T.); +46-(0)8-790-96-27 (T.G.)
| | - Anzhelika Vorobyeva
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85 Uppsala, Sweden; (T.X.); (Y.L.); (O.V.); (A.V.)
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8
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Karsten L, Goett-Zink L, Schmitz J, Hoffrogge R, Grünberger A, Kottke T, Müller KM. Genetically Encoded Ratiometric pH Sensors for the Measurement of Intra- and Extracellular pH and Internalization Rates. BIOSENSORS 2022; 12:bios12050271. [PMID: 35624572 PMCID: PMC9138566 DOI: 10.3390/bios12050271] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/04/2022] [Accepted: 04/11/2022] [Indexed: 12/13/2022]
Abstract
pH-sensitive fluorescent proteins as genetically encoded pH sensors are promising tools for monitoring intra- and extracellular pH. However, there is a lack of ratiometric pH sensors, which offer a good dynamic range and can be purified and applied extracellularly to investigate uptake. In our study, the bright fluorescent protein CoGFP_V0 was C-terminally fused to the ligand epidermal growth factor (EGF) and retained its dual-excitation and dual-emission properties as a purified protein. The tandem fluorescent variants EGF-CoGFP-mTagBFP2 (pK′ = 6.6) and EGF-CoGFP-mCRISPRed (pK′ = 6.1) revealed high dynamic ranges between pH 4.0 and 7.5. Using live-cell fluorescence microscopy, both pH sensor molecules permitted the conversion of fluorescence intensity ratios to detailed intracellular pH maps, which revealed pH gradients within endocytic vesicles. Additionally, extracellular binding of the pH sensors to cells expressing the EGF receptor (EGFR) enabled the tracking of pH shifts inside cultivation chambers of a microfluidic device. Furthermore, the dual-emission properties of EGF-CoGFP-mCRISPRed upon 488 nm excitation make this pH sensor a valuable tool for ratiometric flow cytometry. This high-throughput method allowed for the determination of internalization rates, which represents a promising kinetic parameter for the in vitro characterization of protein–drug conjugates in cancer therapy.
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Affiliation(s)
- Lennard Karsten
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
| | - Lukas Goett-Zink
- Biophysical Chemistry and Diagnostics, Medical School OWL, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany; (L.G.-Z.); (T.K.)
| | - Julian Schmitz
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany; (J.S.); (A.G.)
- Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Raimund Hoffrogge
- Cell Culture Technology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
| | - Alexander Grünberger
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany; (J.S.); (A.G.)
- Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Tilman Kottke
- Biophysical Chemistry and Diagnostics, Medical School OWL, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany; (L.G.-Z.); (T.K.)
| | - Kristian M. Müller
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
- Correspondence:
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