CELLULARLY GENERATED ACTIVE OXYGEN SPECIES AND HELA-CELL PROLIFERATION

In HeLa cells evidence is provided that active oxygen species such as hydrogen peroxide and superoxide at low levels are important growth re gulatory signals. They may constitute a novel regulatory redox system of control superimposed upon the established cell growth signal transd uction pathways. Whilst for ''ample hydrogen peroxide can be added exo genously to elicit growth responses in these cells, it is clear that c ellularly generated superoxide and hydrogen peroxide are important. Ex periments with superoxide dismutase, superoxide dismutase mimics and i nhibitors of both superoxide dismutase and xanthine oxidase suggest th at superoxide generated intracellularly and superoxide released extrac ellularly are both relevant to growth control in HeLa cells.