Bioactivation of Carboxylic Acid Compounds by UDP-Glucuronosyltransferases to DNA-Damaging Intermediates: Role of Glycoxidation and Oxidative Stress in Genotoxicity
详细信息 查看全文
- 作者：Benedetta C. Sallustio ; Yvette C. DeGraaf ; Josephine S. Weekley ; and Philip C. Burcham
- 刊名：Chemical Research in Toxicology
- 出版年：2006
- 出版时间：May 2006
- 年：2006
- 卷：19
- 期：5
- 页码：683 - 691
- 全文大小：272K
- 年卷期：v.19,no.5(May 2006)
- ISSN：1520-5010
文摘
Nonenzymatic modification of proteins by acyl glucuronides is well documented; however, little isknown about their potential to damage DNA. We have previously reported that clofibric acid undergoesglucuronidation-dependent bioactivation to DNA-damaging species in cultured mouse hepatocytes. Theaim of this study was to investigate the mechanisms underlying such DNA damage, and to screenchemically diverse carboxylic acid drugs for their DNA-damaging potential in glucuronidation proficientmurine hepatocytes. Cells were incubated with each aglycone for 18 h, followed by assessment ofcompound cytotoxicity using the MTT assay and evaluation of DNA damage using the Comet assay.Relative cytotoxic potencies were ketoprofen > diclofenac, benoxaprofen, nafenopin 
gemfibrozil,probenecid > bezafibrate > clofibric acid. At a noncytotoxic (0.1 mM) concentration, only benoxaprofen,nafenopin, clofibric acid, and probenecid significantly increased Comet moments (P < 0.05 Kruskal-Wallis). Clofibric acid and probenecid exhibited the greatest DNA-damaging potency, producing significantDNA damage at 0.01 mM concentrations. The two drugs produced maximal increases in Comet momentof 4.51× and 2.57× control, respectively. The glucuronidation inhibitor borneol (1 mM) abolished theinduction of DNA damage by 0.5 mM concentrations of clofibric acid and probenecid. In an in vitrocell-free system, clofibric acid glucuronide was 10× more potent than glucuronic acid in causing DNAstrand-nicking, although both compounds showed similar rates of autoxidation to generate hydroxylradicals. In cultured hepatocytes, the glycation inhibitor, aminoguanidine, and the iron chelator, desferrioxamine mesylate, inhibited DNA damage by clofibric acid, whereas the free radical scavengersTrolox and butylated hydroxytoluene, and the superoxide dismutase mimetic bis-3,5-diisopropylsalicylatehad no effect. In conclusion, clinically relevant concentrations of two structurally unrelated carboxylicacids, probenecid and clofibric acid, induced DNA damage in isolated hepatocytes via glucuronidation-dependent pathways. These findings suggest acyl glucuronides are able to access and damage nuclearDNA via iron-catalyzed glycation/glycoxidative processes.
gemfibrozil,probenecid > bezafibrate > clofibric acid. At a noncytotoxic (0.1 mM) concentration, only benoxaprofen,nafenopin, clofibric acid, and probenecid significantly increased Comet moments (P < 0.05 Kruskal-Wallis). Clofibric acid and probenecid exhibited the greatest DNA-damaging potency, producing significantDNA damage at 0.01 mM concentrations. The two drugs produced maximal increases in Comet momentof 4.51× and 2.57× control, respectively. The glucuronidation inhibitor borneol (1 mM) abolished theinduction of DNA damage by 0.5 mM concentrations of clofibric acid and probenecid. In an in vitrocell-free system, clofibric acid glucuronide was 10× more potent than glucuronic acid in causing DNAstrand-nicking, although both compounds showed similar rates of autoxidation to generate hydroxylradicals. In cultured hepatocytes, the glycation inhibitor, aminoguanidine, and the iron chelator, desferrioxamine mesylate, inhibited DNA damage by clofibric acid, whereas the free radical scavengersTrolox and butylated hydroxytoluene, and the superoxide dismutase mimetic bis-3,5-diisopropylsalicylatehad no effect. In conclusion, clinically relevant concentrations of two structurally unrelated carboxylicacids, probenecid and clofibric acid, induced DNA damage in isolated hepatocytes via glucuronidation-dependent pathways. These findings suggest acyl glucuronides are able to access and damage nuclearDNA via iron-catalyzed glycation/glycoxidative processes.