Free radicals and the regulation of mammalian cell proliferation.

The question of whether free radicals or free radical-related species play a role in the modulation of mammalian cell proliferation is examined. Although a positive role for free radicals as specific components of mitogenic pathways is not apparent it is clear that certain free radical-derived species can have a significant modulatory influence on components of major growth signal transduction mechanisms. Free radical-derived species are also involved in the production of prostaglandins which themselves can modulate cell growth. Free radicals themselves appear to have a down regulatory effect on cell proliferation inasmuch as protection from oxidative stress enhances cell proliferation. On the other hand, in certain cases low levels of active oxygen species can enhance cell proliferation.