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Ritler A, Shoshan MS, Deupi X, Wilhelm P, Schibli R, Wennemers H, Béhé M. Elucidating the Structure-Activity Relationship of the Pentaglutamic Acid Sequence of Minigastrin with Cholecystokinin Receptor Subtype 2. Bioconjug Chem 2019; 30:657-666. [PMID: 30608664 DOI: 10.1021/acs.bioconjchem.8b00849] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Derivatized minigastrin analogues make up a promising class of candidates for targeting cholecystokinin receptor subtype 2 (CCK2R), which is overexpressed on cancer cells of various neuroendocrine tumors. The pentaglutamic acid sequence of minigastrin influences its biological properties. In particular, it plays a crucial role in the kidney reuptake mechanism. However, the importance of the binding affinity and interaction of this region with the receptor on a molecular level remains unclear. To elucidate its structure-activity relationship with CCK2R, we replaced this sequence with various linkers differing in their amount of anionic charge, structural characteristics, and flexibility. Specifically, a flexible aliphatic linker, a linker with only three d-Glu residues, and a structured linker with four adjacent β3-glutamic acid residues were evaluated and compared to the lead compound PP-F11N (DOTA-[d-Glu1-6,Nle11]gastrin-13). 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was conjugated to the minigastrin derivatives, which allowed radiolabeling with Lutetium-177. The levels of In vitro internalization into MZ-CRC1 cells and in vivo tumor uptake as well as human blood plasma stability increased in the following order: aliphatic linker < three d-Glu < (β3-Glu)4 < (d-Glu)6. The in vitro and in vivo behavior was therefore significantly improved with anionic charges. Computational modeling of a CCK2 receptor-ligand complex revealed ionic interactions between cationic residues (Arg and His) of the receptor and anionic residues of the ligand in the linker.
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Affiliation(s)
- Andreas Ritler
- Department of Chemistry and Applied Biosciences (D-CHAB), Laboratory of Organic Chemistry (LOC) , ETH , CH-8093 Zurich , Switzerland.,Department of Chemistry and Applied Biosciences (D-CHAB), Institute of Pharmaceutical Sciences (IPW) , ETH , CH-8093 Zurich , Switzerland.,Research Department of Biology and Chemistry, Center for Radiopharmaceutical Sciences (CRS) , Paul Scherrer Institute , CH-5232 Villigen , Switzerland
| | - Michal S Shoshan
- Department of Chemistry and Applied Biosciences (D-CHAB), Laboratory of Organic Chemistry (LOC) , ETH , CH-8093 Zurich , Switzerland
| | - Xavier Deupi
- Laboratory of Biomolecular Research and Condensed Matter Theory Group , Paul Scherrer Institute , CH-5232 Villigen , Switzerland
| | - Patrick Wilhelm
- Department of Chemistry and Applied Biosciences (D-CHAB), Laboratory of Organic Chemistry (LOC) , ETH , CH-8093 Zurich , Switzerland
| | - Roger Schibli
- Department of Chemistry and Applied Biosciences (D-CHAB), Institute of Pharmaceutical Sciences (IPW) , ETH , CH-8093 Zurich , Switzerland.,Research Department of Biology and Chemistry, Center for Radiopharmaceutical Sciences (CRS) , Paul Scherrer Institute , CH-5232 Villigen , Switzerland
| | - Helma Wennemers
- Department of Chemistry and Applied Biosciences (D-CHAB), Laboratory of Organic Chemistry (LOC) , ETH , CH-8093 Zurich , Switzerland
| | - Martin Béhé
- Research Department of Biology and Chemistry, Center for Radiopharmaceutical Sciences (CRS) , Paul Scherrer Institute , CH-5232 Villigen , Switzerland
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Lipiński PFJ, Garnuszek P, Maurin M, Stoll R, Metzler-Nolte N, Wodyński A, Dobrowolski JC, Dudek MK, Orzełowska M, Mikołajczak R. Structural studies on radiopharmaceutical DOTA-minigastrin analogue (CP04) complexes and their interaction with CCK2 receptor. EJNMMI Res 2018; 8:33. [PMID: 29663167 PMCID: PMC5902437 DOI: 10.1186/s13550-018-0387-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 04/06/2018] [Indexed: 12/16/2022] Open
Abstract
Background The cholecystokinin receptor subtype 2 (CCK-2R) is an important target for diagnostic imaging and targeted radionuclide therapy (TRNT) due to its overexpression in certain cancers (e.g., medullary thyroid carcinoma (MTC)), thus matching with a theranostic principle. Several peptide conjugates suitable for the TRNT of MTC have been synthesized, including a very promising minigastrin analogue DOTA-(DGlu)6-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2 (CP04). In this contribution, we wanted to see whether CP04 binding affinity for CCK-2R is sensitive to the type of the complexed radiometal, as well as to get insights into the structure of CP04-CCK2R complex by molecular modeling. Results In vitro studies demonstrated that there is no significant difference in CCK-2R binding affinity and specific cellular uptake between the CP04 conjugates complexed with [68Ga]Ga3+ or [177Lu]Lu3+. In order to investigate the background of this observation, we proposed a binding model of CP04 with CCK-2R based on homology modeling and molecular docking. In this model, the C-terminal part of the molecule enters the cavity formed between the receptor helices, while the N-terminus (including DOTA and the metal) is located at the binding site outlet, exposed in large extent to the solvent. The radiometals do not influence the conformation of the molecule except for the direct neighborhood of the chelating moiety. Conclusions The model seems to be in agreement with much of structure-activity relationship (SAR) studies reported for cholecystokinin and for CCK-2R-targeting radiopharmaceuticals. It also explains relative insensitivity of CCK-2R affinity for the change of the metal. The proposed model partially fits the reported site-directed mutagenesis data.
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Affiliation(s)
- Piotr F J Lipiński
- Neuropeptides Department, Mossakowski Medical Research Centre Polish Academy of Sciences, Pawińskiego 5 Str., 02-106, Warszawa, Poland.
| | - Piotr Garnuszek
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, A. Sołtana 7 Str, 05-400, Otwock, Poland
| | - Michał Maurin
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, A. Sołtana 7 Str, 05-400, Otwock, Poland
| | - Raphael Stoll
- Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Nils Metzler-Nolte
- Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Artur Wodyński
- Świerk Computing Centre, National Centre for Nuclear Research, A. Sołtana 7 Str., 05-400, Otwock, Poland.,Institut für Chemie, Theoretische Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Jan Cz Dobrowolski
- Institute of Nuclear Chemistry and Technology, Dorodna 16 Street, 03-195, Warszawa, Poland.,National Medicines Institute, Chełmska 30/34 Str., 00-725, Warszawa, Poland
| | - Marta K Dudek
- Centre of Molecular and Macromolecular Studies Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland
| | - Monika Orzełowska
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, A. Sołtana 7 Str, 05-400, Otwock, Poland
| | - Renata Mikołajczak
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, A. Sołtana 7 Str, 05-400, Otwock, Poland
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Dormán G, Nakamura H, Pulsipher A, Prestwich GD. The Life of Pi Star: Exploring the Exciting and Forbidden Worlds of the Benzophenone Photophore. Chem Rev 2016; 116:15284-15398. [PMID: 27983805 DOI: 10.1021/acs.chemrev.6b00342] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The widespread applications of benzophenone (BP) photochemistry in biological chemistry, bioorganic chemistry, and material science have been prominent in both academic and industrial research. BP photophores have unique photochemical properties: upon n-π* excitation at 365 nm, a biradicaloid triplet state is formed reversibly, which can abstract a hydrogen atom from accessible C-H bonds; the radicals subsequently recombine, creating a stable covalent C-C bond. This light-directed covalent attachment process is exploited in many different ways: (i) binding/contact site mapping of ligand (or protein)-protein interactions; (ii) identification of molecular targets and interactome mapping; (iii) proteome profiling; (iv) bioconjugation and site-directed modification of biopolymers; (v) surface grafting and immobilization. BP photochemistry also has many practical advantages, including low reactivity toward water, stability in ambient light, and the convenient excitation at 365 nm. In addition, several BP-containing building blocks and reagents are commercially available. In this review, we explore the "forbidden" (transitions) and excitation-activated world of photoinduced covalent attachment of BP photophores by touring a colorful palette of recent examples. In this exploration, we will see the pros and cons of using BP photophores, and we hope that both novice and expert photolabelers will enjoy and be inspired by the breadth and depth of possibilities.
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Affiliation(s)
- György Dormán
- Targetex llc , Dunakeszi H-2120, Hungary.,Faculty of Pharmacy, University of Szeged , Szeged H-6720, Hungary
| | - Hiroyuki Nakamura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology , Yokohama 226-8503, Japan
| | - Abigail Pulsipher
- GlycoMira Therapeutics, Inc. , Salt Lake City, Utah 84108, United States.,Division of Head and Neck Surgery, Rhinology - Sinus and Skull Base Surgery, Department of Surgery, University of Utah School of Medicine , Salt Lake City, Utah 84108, United States
| | - Glenn D Prestwich
- Division of Head and Neck Surgery, Rhinology - Sinus and Skull Base Surgery, Department of Surgery, University of Utah School of Medicine , Salt Lake City, Utah 84108, United States
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