Developing an Irreversible Inhibitor of Human DDAH‐1, an Enzyme Upregulated in Melanoma |
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Authors: | Dr. Yun Wang Dr. Shougang Hu Abdul M. Gabisi Jr. Joyce A. V. Er Arthur Pope Gayle Burstein Christopher L. Schardon Dr. Arturo J. Cardounel Dr. Suhendan Ekmekcioglu Dr. Walter Fast |
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Affiliation: | 1. Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, 1 University Station,Code C0850, Austin, TX, 78712 (USA);2. Department of Melanoma Medical Oncology, M.D. Anderson Cancer Center, Houston, TX, 77030 (USA);3. Departments of Internal Medicine and Pharmacology, Ohio State University Medical Center, Columbus, OH 43210 (USA);4. Department of Biochemistry, College of Natural Sciences, University of Texas at Austin, 1 University Station, Austin TX, 78712 (USA) |
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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, N5‐(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. |
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Keywords: | covalent inhibitors dimethylaminohydrolase dimethylarginine melanoma nitric oxide |
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