Depurinating Acylfulvene-DNA Adducts: Characterizing Cellular Chemical Reactions of a Selective Antitumor Agent

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• 作者：Jiachang Gong ; V. G. Vaidyanathan ; Xiang Yu ; Thomas W. Kensler ; Lisa A. Peterson ; Shana J. Sturla
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：February 21, 2007
• 年：2007
• 卷：129
• 期：7
• 页码：2101 - 2111
• 全文大小：217K
• 年卷期：v.129,no.7(February 21, 2007)
• ISSN：1520-5126

文摘

Acylfulvenes (AFs) are a class of semisynthetic agents with high toxicity toward certain tumorcells, and for one analogue, hydroxymethylacylfulvene (HMAF), clinical trials are in progress. DNA alkylationby AFs, mediated by bioreductive activation, is believed to contribute to cytotoxicity, but the structures andchemical properties of corresponding DNA adducts are unknown. This study provides the first structuralcharacterization of AF-specific DNA adducts. In the presence of a reductive enzyme, alkenal/oneoxidoreductase (AOR), AF selectively alkylates dAdo and dGuo in reactions with a monomeric nucleoside,as well as in reactions with naked or cellular DNA, with 3-alkyl-dAdo as the apparently most abundantAF-DNA adduct. Characterization of this adduct was facilitated by independent chemical synthesis of thecorresponding 3-alkyl-Ade adduct. In addition, in naked or cellular DNA, evidence was obtained for theformation of an additional type of adduct resulting from direct conjugate addition of Ade to AF followed byhydrolytic cyclopropane ring-opening, indicating the potential for a competing reaction pathway involvingdirect DNA alkylation. The major AF-dAdo and AF-dGuo adducts are unstable under physiologically relevantconditions and depurinate to release an alkylated nucleobase in a process that has a half-life of 8.5 h for3-alkyladenine and less than approximately 2 h for dGuo adducts. DNA alkylation further leads to single-stranded DNA cleavage, occurring exclusively at dGuo and dAdo sites, in a nonsequence-specific manner.In AF-treated cells that were transfected with either AOR or control vectors, the DNA adducts identifiedmatch those from in vitro studies. Moreover, a positive correlation was observed between DNA adductlevels and cell sensitivity to AF. The potential contributing roles of AOR-mediated bioactivation and adductstability to the cytotoxicity of AF are discussed.