Regulation of tumor cell proliferation and apoptosis by free radicals

It has been studied the influence of oxygen raical generating compounds including superoxide anion radical and organic peroxic radicals on proliferation and apoptosis of tumor cells in vitro. These compouns dose-dependently supressed DNA synthesis and induced apoptosis of Ehrlich carcinoma cells in high concentration (10"5 M to 10'3M) and stimulated proliferation when the concentration was lower 10'6 M. One of the possible mechanismes of acting agent content decrease before their entrance into the cells is the extracellular production of glutathion peroxidase and low-molecular antiradical substances. Antioxidant enzymes play an important role in intracellular maintenance of free radical oxidation level. Their activities were decreased during the phase of active proliferation and increased when the cells passed to a phase of slow stationary growth.