title: Developing an irreversible inhibitor of human DDAH-1, an enzyme upregulated in melanoma.
abstract: Inhibitors of the human enzyme dimethylarginine dimethylaminohydrolase-1 (DDAH-1) can raise endogenous levels of asymmetric dimethylarginine (ADMA) and lead to a subsequent inhibition of nitric oxide synthesis. In this study, N(5) -(1-imino-2-chloroethyl)-L-ornithine (Cl-NIO) is shown to be a potent time- and concentration-dependent inhibitor of purified human DDAH-1 (KI =1.3±0.6 μM; kinact =0.34±0.07 min(-1) ), with >500-fold selectivity against two arginine-handling enzymes in the same pathway. An activity probe is used to measure the "in cell" IC50 value (6.6±0.2 μM) for Cl-NIO inhibition of DDAH-1 artificially expressed within cultured HEK293T cells. A screen of diverse melanoma cell lines reveals that a striking 50/64 (78 %) of melanoma lines tested showed increased levels of DDAH-1 relative to normal melanocyte control lines. Treatment of the melanoma A375 cell line with Cl-NIO shows a subsequent decrease in cellular nitric oxide production. Cl-NIO is a promising tool for the study of methylarginine-mediated nitric oxide control and a potential therapeutic lead compound for other indications with elevated nitric oxide production, such as septic shock and idiopathic pulmonary fibrosis.
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, 1 University Station,Code C0850, Austin, TX, 78712 (USA).
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Shougang
authors.initials: S
authors.lastname: Hu
authors.forename: Abdul M
authors.initials: AM
authors.lastname: Gabisi
authors.forename: Joyce A V
authors.initials: JA
authors.lastname: Er
authors.forename: Arthur
authors.initials: A
authors.lastname: Pope
authors.forename: Gayle
authors.initials: G
authors.lastname: Burstein
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Schardon
authors.forename: Arturo J
authors.initials: AJ
authors.lastname: Cardounel
authors.forename: Suhendan
authors.initials: S
authors.lastname: Ekmekcioglu
authors.forename: Walter
authors.initials: W
authors.lastname: Fast
mesh_terms: D000581:Amidohydrolases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D008545:Melanoma / Q000201:enzymology* / Q000378:metabolism; D008968:Molecular Conformation; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D009952:Ornithine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; C000593556:N(5)-(1-imino-2-chloroethyl)ornithine; D009569:Nitric Oxide; D009952:Ornithine; D000581:Amidohydrolases; C059999:dimethylargininase
keywords: covalent inhibitors; dimethylaminohydrolase; dimethylarginine; melanoma; nitric oxide