In vivo bioassay to detect irinotecan-stabilized DNA/topoisomerase I complexes in rats |
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| Authors: | Stephan W Barth Karlis Briviba Bernhard Watzl Nicole Jäger Doris Marko Melanie Esselen Dr |
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| Institution: | 1. Department of nutrition Physiology and Biochemistry, Max Rubner-Institute, Karlsruhe, Germany;2. Institute of Applied Biosciences, Section of Food Toxicology, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany;3. Institute of Applied Biosciences, Section of Food Toxicology, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
Institute of Analytical and Food Chemistry, University of Vienna, Vienna, Austria |
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| Abstract: | Irinotecan is an anticancer agent that stabilizes topoisomerase I/DNA complexes. So far, no test system has been reported for directly determining irinotecan-induced stabilization of topoisomerase I/DNA complexes in organs in vivo. We adapted an ‘in vivo complexes of enzyme to DNA’ (ICE) bioassay to assess irinotecan activity in the stomach, duodenum, colon and liver of male Wistar rats after a single treatment with irinotecan (100 mg/kg body weight, intraperitoneally). This was compared to the control group receiving 0.9% sodium chloride intraperitoneally. In addition, the DNA strand breaking properties of irinotecan were measured in mucosal cells from the distal colon by single-cell gel electrophoresis (comet assay) to investigate the association of topoisomerase poisoning and DNA damage in vivo. A single dose of irinotecan significantly increased amounts of topoisomerase I covalently bound to DNA in stomach, duodenum, colon and liver. Concomitantly, the irinotecan-treated group showed significantly higher amounts of DNA strand breaks in colon mucosa cells compared to the control group. The ICE bioassay and the comet assay represent two test systems for investigating the impact of topoisomerase I poisons on DNA integrity in colon tissues of Wistar rats. |
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| Keywords: | Cleavable complex Comet assay DNA strand breaks Methods Topoisomerase poison |
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