Heparin and Liver Heparan Sulfate Can Rescue Hepatoma Cells from Topotecan Action

Figure 5

Effect of heparin treatment on topoisomerase I plasmid relaxation activity of HepG2 and Hep3B cells (representative image of three independent experiments). Cells were plated to 6 well plates at  cells/plate and grown for 24 h in the presence of 5% fetal calf serum. Subsequently, the serum was replaced with bovine serum albumin (BSA), and the cells were exposed to 100 μg/mL heparin for 24 h (lanes 4 and 7) and 48 h (lanes 5 and 8). Cell nuclear extracts were used for topo I relaxation activity measurements as described. Heparin exposure for 48 hours resulted in total loss of enzyme activity of Hep3B cells (lane 5). Heparin did not affect the activity of HepG2 cells (lanes 4 and 5). Lane 1: DNA size standard, 1 kiloBase (kB) ladder; lane 2: plasmid control without protein (S: superhelix, R: relaxed); lanes 3 and 6: plasmid relaxation in untreated cells.