Superoxide radical potentiates invasive capacity of rat ascites hepatoma cells in vitro.

Effect of superoxide radical (O2-) produced extracellularly by hypoxanthine (HX) and xanthine oxidase (XO) on invasive capacity of rat ascites hepatoma cells was studied. Invasive capacity was estimated in vitro by counting the number of tumor cell colonies penetrated underneath cultured mesothelial cell monolayer. When the tumor cells had been treated with non-toxic doses of HX and XO, the formation of penetrated colonies increased with increasing concentrations of XO. This increment was completely inhibited by scavengers of active oxygen radicals, superoxide dismutase (SOD) in combination with catalase (CAT) added simultaneously at the time of HX-XO treatment.