Development of a pharmacologically improved peptide agonist of the leptin receptor.
Leptin, a hormone produced by adipose tissue, regulates energy balance in the hypothalamus and is involved in fertility, immune response and carcinogenesis. The existence of disorders related to leptin deficit and leptin overabundance calls for the development of drugs activating or inhibiting the leptin receptor (ObR). We synthesized four proposed receptor-binding leptin fragments (sites I, IIa and IIb, III), their reportedly antagonist analogs, and a peptide chimera composed of the two discontinuous site II arms. To assess the pharmacological utility of leptin fragments, we studied the peptides' ability to stimulate the growth of ObR-positive and ObR-negative cells. The combined site II construct and site III derivatives selectively reversed leptin-induced growth of ObR-positive cells at mid-nanomolar concentrations. However, these peptides appeared to be partial agonists/antagonists as they activated cell growth in the absence of exogenous leptin. A designer site III analog, featuring non-natural amino acids at terminal positions to decrease proteolysis and a blood-brain barrier (BBB) penetration-enhancing carbohydrate moiety, proved to be full agonist to ObR, i.e., stimulated proliferation of different ObR-positive but not ObR-negative cells in the presence or absence of leptin. This glycopeptide bound to isolated ObR on solid-phase assays and activated ERK-1/2 signaling in ObR-positive MCF-7 cells at 100-500 nM concentrations. The glycopeptide was stable in mouse serum, readily crossed endothelial/astrocyte cell layers in a cellular BBB model, and was distributed into the brain of Balb/c mice after intraperitoneal administration. These characteristics suggest a potential pharmaceutical utility of the designer site III glycopeptide in leptin-deficient diseases.
Temple University, Sbarro Institute of Cancer Research and Molecular Medicine, 1900 North 12th Street, Philadelphia, PA 19122, USA. otvos@temple.edu
Laszlo
L
Otvos
Marianna
M
Terrasi
Sandra
S
Cascio
Marco
M
Cassone
Giovanni
G
Abbadessa
Francesco
F
De Pascali
Laura
L
Scolaro
Daniel
D
Knappe
Maciej
M
Stawikowski
Predrag
P
Cudic
John D
JD
Wade
Ralf
R
Hoffmann
Eva
E
Surmacz
D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D054411:Receptors, Leptin / Q000819:agonists* / Q000378:metabolism
D010455:Peptides; D054411:Receptors, Leptin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3