Research Article Heparin and Liver Heparan Sulfate Can Rescue Hepatoma Cells from Topotecan Action József Dudás, 1,2 József Bocsi, 2 Alexandra Fullár, 2 Kornélia Baghy, 2 Tibor Füle, 2 Saule Kudaibergenova, 1,3 and Ilona Kovalszky 2 1 Department Otorhinolaryngology, Medical University Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria 2 First Institute of Pathology & Experimental Cancer Research, Faculty of Medicine, Semmelweis University, ¨ Ull¨ oi ´ ut 26, 1085 Budapest, Hungary 3 Department of Otorhinolaryngology, Faculty Medical Department, Asfendiyarov Kazakh National Medical University, Specialty Otorhinolaryngology, Index 05-00-12, Almaty, Kazakhstan Correspondence should be addressed to Ilona Kovalszky; koval@korb1.sote.hu Received 29 May 2014; Revised 23 July 2014; Accepted 12 August 2014; Published 7 September 2014 Academic Editor: George Tzanakakis Copyright © 2014 J´ ozsef Dud´ as et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Topotecan (TpT) is a major inhibitory compound of topoisomerase (topo) I that plays important roles in gene transcription and cell division. We have previously reported that heparin and heparan sulfate (HS) might be transported to the cell nucleus and they can interact with topoisomerase I. We hypothesized that heparin and HS might interfere with the action of TpT. To test this hypothesis we isolated topoisomerase I containing cell nuclear protein fractions from normal liver, liver cancer tissues, and hepatoma cell lines. he enzymatic activity of these extracts was measured in the presence of heparin, liver HS, and liver cancer HS. In addition, topo I activity, cell viability, and apoptosis of HepG2 and Hep3B cells were investigated ater heparin and TpT treatments. Liver cancer HS inhibited topo I activity in vitro. Heparin treatment abrogated topo I enzyme activity in Hep3B cells, but not in HepG2 cells, where the basal activity was higher. Heparin protected the two hepatoma cell lines from TpT actions and decreased the rate of TpT induced S phase block and cell death. hese results suggest that heparin and HS might interfere with the function of TpT in liver and liver cancer. 1. Introduction Heparin and heparan sulfate (HS) are polysulfated sugars, members of glycosaminoglycans (GAGs), present in animal and human tissue in free or protein bound forms. Heparan sulfate glycanated proteins are found in the extracellular matrix and on the cell surface [1]. Recent studies provide ample evidence on the central role of these molecules in cell life including cellular organization, cell behavior, and cell signaling [1, 2]. Heparin und heparan sulfates bind several growth factors [3–7], hormones [8], cytokines [6, 9], and chemokines [10, 11] that are implicated in cell regulation [12] in several ways. he cellular role of HS has been studied for years without a major breakthrough achieved [13–18]. Biochemical approaches failed to collect convincing data for intracellu- lar proteoglycan activity. Recently tentative evidences were provided supporting the regulatory efect of HS on cell proliferation and showing that these GAGs afect DNA- transcription factor interactions [19]. Our previous experi- ments resulted in similar conclusions [17]. For the irst time confocal microscopy evidenced the nuclear localization of GAGs and proteoglycans [20–22]. Since then the nuclear function of proteoglycans is coming to focus of interest [22]. Nevertheless, the issue is still an elusive part of proteoglycan research. We reported that heparin and liver HS inhibit the plasmid relaxation activity of topoisomerase I enzyme in vitro [21]. Furthermore, we provided evidence for heparin and HS cel- lular uptake and accumulation in the nucleus [17, 22]. hese observations motivated us to investigate if GAG molecules are able to interfere with topoisomerase I (topo I) activity and modify the efect of topo I inhibitory drug topotecan (TpT) [23]. Hindawi Publishing Corporation BioMed Research International Volume 2014, Article ID 765794, 8 pages http://dx.doi.org/10.1155/2014/765794