title: Small molecule inhibitors of methionine aminopeptidase type 2 (MetAP-2).
abstract: The protein processing enzyme, methionine aminopeptidase-2 (MetAP-2), has been identified as a molecular target of fumagillin and its derivative, TNP-470, compounds known to inhibit endothelial cell proliferation and angiogenesis. A high-throughput screening program was undertaken to identify selective, reversible inhibitors of MetAP-2 in an attempt to discover structurally novel anti-angiogenic agents for potential therapeutic use in oncology. Approximately 90 small-molecule, reversible, selective inhibitors of rhMetAP-2 were identified. The most potent of these compounds contained a singly-substituted triazole moiety which exhibited an IC50 of 8 nM (95% confidence limits 5 to 13 nM) and was highly selective for MetAP-2 over MetAP-1 (approximately 60-fold difference in IC50 values). Unlike fumagillin, these MetAP-2 inhibitors failed to significantly inhibit growth factor-stimulated endothelial cell (HUVEC) proliferation or to suppress angiogenesis in the in vitro aortic ring explant model of microvessel outgrowth. The MetAP-2-inhibitory activity of these compounds was dependent on the divalent cation used as the metalloenzyme activating cofactor for MetAP-2. These inhibitors were identified using cobalt(II)-activated recombinant human MetAP-2 for screening compound libraries. When manganese (Mn2+) was substituted for cobalt following EDTA treatment and extensive dialysis of the MetAP-2 protein, these inhibitors were significantly less potent (40-fold increase in IC50) as inhibitors of MetAP-2. These results support the recent hypothesis that cobalt may not be the relevant divalent metal ion cofactor for MetAP-2 in cells and may explain the observed absence of cell-based activity using potent triazole inhibitors of cobalt-activated MetAP-2.
authors.affiliation: Drug Discovery, Johnson & Johnson Pharmaceutical Research and Development, LLC, Spring House, Pennsylvania 19477, USA. tgarrabr@prdus.jnj.com
authors.forename: Thomas
authors.initials: T
authors.lastname: Garrabrant
authors.forename: Robert W
authors.initials: RW
authors.lastname: Tuman
authors.forename: Don
authors.initials: D
authors.lastname: Ludovici
authors.forename: Rose
authors.initials: R
authors.lastname: Tominovich
authors.forename: Richard L
authors.initials: RL
authors.lastname: Simoneaux
authors.forename: Robert A
authors.initials: RA
authors.lastname: Galemmo
authors.forename: Dana L
authors.initials: DL
authors.lastname: Johnson
mesh_terms: D000626:Aminopeptidases / Q000037:antagonists & inhibitors*; D020533:Angiogenesis Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D001011:Aorta; D049109:Cell Proliferation / Q000187:drug effects*; D003510:Cyclohexanes; D004353:Drug Evaluation, Preclinical; D004730:Endothelium, Vascular / Q000166:cytology* / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006023:Glycoproteins / Q000037:antagonists & inhibitors*; D006801:Humans; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors*; D063208:Methionyl Aminopeptidases; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D000077609:O-(Chloroacetylcarbamoyl)fumagillol; D012717:Sesquiterpenes / Q000494:pharmacology; D013329:Structure-Activity Relationship; D014471:Umbilical Veins
chemical_list: D020533:Angiogenesis Inhibitors; D003510:Cyclohexanes; D004791:Enzyme Inhibitors; D005231:Fatty Acids, Unsaturated; D006023:Glycoproteins; D012717:Sesquiterpenes; C026211:fumagillin; D000626:Aminopeptidases; C081311:METAP2 protein, human; D063208:Methionyl Aminopeptidases; C106541:methionine aminopeptidase 2; D008666:Metalloendopeptidases; D000077609:O-(Chloroacetylcarbamoyl)fumagillol