Interstrand Cross-Linking of DNA by FK317 and Its Deacetylated Metabolites FR70496 and FR157471

Abstract

FR900482 (1) and FR66979 (2) are structurally novel natural products isolated by Fujisawa in 1987 and have been shown to be highly potent antitumor antibiotics structurally related to the mitomycins. Studies on the mode of action have established that these new agents form covalent DNA interstrand cross-links both in vitro and in vivo as a result of the reactive mitosene intermediate generated upon bioreductive activation. Semisynthetic analogues such as FK973 (3) and FK317 (4) were developed in the search for potentially superior clinical candidates. Although FK317 has been shown to be a potent compound, to date no direct evidence of DNA interstrand cross-link sequence specificity has been reported. In this study, DNA interstrand cross-links were generated by treatment of a synthetic duplex DNA substrate with FK317 (4) and its deacetylated metabolites FR70496 (5) and FR157471 (6). Analysis by gel electrophoresis revealed the formation of orientation isomers displaying electrophoretic mobility vastly greater than the mobilities of those generated from FR900482 (1). Despite these differences, it was established by Fe(II)-EDTA footprinting that FK317 (4) as well as 5 and 6 forms DNA interstrand cross-links within the expected 5'CpG3' step, clearly demonstrating that the phenolic hydrogen in 1 and 2 is not a prerequisite for efficient DNA interstrand cross-linking by the FR class of compounds.

Aziridine Natural Products – Discovery, Biological Activity and Biosynthesis

“…The mechanism outlined in Figure 11.2 was originally proposed by Goto and Fukuyama [78] and has been verified by the experimental work of Williams and Hopkins [71][72][73][74][75][76][77]79]. Reduction of the N-O bond produces intermediate 27, which can lose a molecule of water to form 28, which reacts with DNA by a mechanism similar to that found for the mitomycins.…”

“…Like the mitomycins, FR900482 (6), FR66979 (7), FK973 (8), and FK317 (9) have also been shown to crosslink DNA both in vivo [68][69][70], and in vitro after reductive activation [71][72][73][74][75][76] with selectivity for the 5'-CpG-3' sequence [77]. The mechanism outlined in Figure 11.2 was originally proposed by Goto and Fukuyama [78] and has been verified by the experimental work of Williams and Hopkins [71][72][73][74][75][76][77]79].…”

DNA Interstrand Cross-Linking Agents and their Chemotherapeutic Potential

“…8) [14]. Williams' study provided clear evidence of ICL formation induced by 27 as well as 28 and 29 within the 5´C pG 3´ step.…”

“…The mechanism of cross-link formation comprises two-electron reduction of the N-O with subsequent water elimination and the appearance of mitosene species 30. Over the last decade other work focused on the design and synthesis of pro-mitosenes [14,15]. One of the reports introduced the synthesis of masked mitosene progenitors with the general structure 31 (Fig.…”

Aziridine alkaloids as potential therapeutic agents

“…Although FK317 has been shown to be a potent cytotoxic compound, to date no direct evidence of DNA interstrand crosslink sequence specificity has been reported. In one study, DNA interstrand crosslinks were generated by treatment of a synthetic duplex DNA substrate with FK317 and its deacetylated metabolites FR70496 (25) and FR157471 [77]. FK973 and all its deacetylated metabolites showed strong cytotoxicity on in vitro cultured murine L1210 leukemia cells; however FK973 remained the most potent cytotoxic agent of this series [78].…”