Synthesis and evaluation of bivalent ligands for binding to the human melanocortin-4 receptor.

TitleSynthesis and evaluation of bivalent ligands for binding to the human melanocortin-4 receptor.
Publication TypeJournal Article
Year of Publication2014
AuthorsFernandes SM, Lee YSun, Gillies RJ, Hruby VJ
JournalBioorg Med Chem
Date Published2014 Nov 15
KeywordsAmino Acid Sequence, HEK293 Cells, Humans, Kinetics, Lanthanoid Series Elements, Ligands, Melanocyte-Stimulating Hormones, Oligopeptides, Protein Binding, Receptor, Melanocortin, Type 4

Membrane proteins, especially G-protein coupled receptors (GPCRs), are interesting and important theragnostic targets since many of them serve in intracellular signaling critical for all aspects of health and disease. The potential utility of designed bivalent ligands as targeting agents for cancer diagnosis and/or therapy can be evaluated by determining their binding to the corresponding receptors. As proof of concept, GPCR cell surface proteins are shown to be targeted specifically using multivalent ligands. We designed, synthesized, and tested a series of bivalent ligands targeting the over-expressed human melanocortin 4 receptor (hMC4R) in human embryonic kidney (HEK) 293 cells. Based on our data suggesting an optimal linker length of 25±10Å inferred from the bivalent melanocyte stimulating hormone (MSH) agonist, the truncated heptapeptide, referred to as MSH(7): Ac-Ser-Nle-Glu-His-D-Phe-Arg-Trp-NH2 was used to construct a set of bivalent ligands incorporating a hMC4R antagonist, SHU9119: Ac-Nle-c[Asp-His-2'-D-Nal-Arg-Trp-Lys]-NH2 and another set of bivalent ligands containing the SHU9119 antagonist pharmacophore on both side of the optimized linkers. These two binding motifs within the bivalent constructs were conjoined by semi-rigid (Pro-Gly)3 units with or without the flexible poly(ethylene glycol) (PEGO) moieties. Lanthanide-based competitive binding assays showed bivalent ligands binds to the hMC4R with up to 240-fold higher affinity than the corresponding linked monovalent ligands.

Alternate JournalBioorg. Med. Chem.
PubMed ID25438759
PubMed Central IDPMC4254589
Grant ListR41 CA108040 / CA / NCI NIH HHS / United States
R01 CA097360 / CA / NCI NIH HHS / United States
R01 DA013449 / DA / NIDA NIH HHS / United States
R01 GM108040 / GM / NIGMS NIH HHS / United States
R01 CA108040 / CA / NCI NIH HHS / United States