Influence of ascorbic acid on the activity of the investigational anticancer drug KP1019

Author(s)
Caroline Bartel, Michael Jakupec, Petra Heffeter, Mathea Sophia Galanski, Walter Berger, Bernhard Keppler
Abstract

Ascorbic acid has been previously discussed to have antitumor potential through its interaction with transition metal ions such as iron and copper. Furthermore, ascorbic acid may act as a reducing agent for Ru(III) compounds such as indazolium trans-[tetrachlorobis(1H-indazole)ruthenate(III)] (KP1019), an investigational anticancer drug which is supposed to be activated by reduction, prior to binding to cellular target proteins. Therefore, we investigated the influence of ascorbic acid on the activity of this antitumor metal complex in cell culture studies. We show that co-incubation of equicytotoxic, constant amounts of KP1019 with high concentrations of ascorbic acid (50-700 mu M) increases cytotoxicity of the ruthenium anticancer drug in the human colon carcinoma cell line SW480, human cervical carcinoma KB-3-1 cells, and the multidrug-resistant subline KBC-1, whereas addition of low concentrations (2.7-50 mu M) has a strong chemoprotective effect in the human colon carcinoma cell line SW480, but not in multidrug-resistant KBC-1 cells. Although cellular uptake of KP1019 is not altered, ascorbic acid induce stronger interaction of the ruthenium compound with DNA both in SW480 cells and under cell-free conditions with plasmid DNA. Even if DNA interactions probably play a subordinate role in vivo given the extensive protein binding of the compound, our data exemplify that ascorbic acid enhances the reactivity of KP1019 with biomolecules. Moreover, we demonstrate that the levels of KP1019-generated reactive oxygen species are markedly decreased by co-incubation with ascorbic acid. Conclusively, our results indicate that application of high doses of ascorbic acid might increase the anticancer effects of KP1019.

Organisation(s)
Department of Inorganic Chemistry
External organisation(s)
Medizinische Universität Wien
Journal
Journal of Biological Inorganic Chemistry
Volume
16
Pages
1205-1215
No. of pages
11
ISSN
0949-8257
Publication date
2011
Peer reviewed
Yes
Austrian Fields of Science 2012
104003 Inorganic chemistry
Portal url
https://ucrisportal.univie.ac.at/en/publications/1c43df25-0057-4f7a-87b9-736a31ea2e2e