[Factors reducing the superoxide dismutase activity of the liver of rats with Pliss lymphosarcoma]. / O faktorakh ponizheniia superoksiddismutaznoi aktivnosti v pecheni krys s limfosarkomoi Plissa.

The procedures for isolation and purification of Cu/Zn superoxide dismutase (SOD) from small amounts of rat liver at different stages of Pliss lymphosarcoma growth were developed. Two stages of tumour growth were distinguished. At the first stage (4-5th day after reinoculation) the intensity of optical (680 nm) and EPR spectra of SOD was decreased, on the average, to 30%, while at the second stage--by 40% at 680 nm and by 32%, at 260 nm. The intensity of the EPR spectra was also diminished by 40% as compared to the control. It was assumed that at initial stages of tumour growth the decrease of the SOD activity is mainly due to the reduction of enzyme Cu, while at the second stage--to the decrease of the protein content. In all probability, the observed changes are induced by the activation of lipid peroxidation involving active O2 species. The second stage is associated with the superoxide-induced impairment of the function of nucleic acids involved in protein biosynthesis.

[Superoxide-producing lipoprotein as a tumor growth suppressing factor, increasing the number of leukocytes and accelerating cell division in culture]. / Superoksid-produtsiruiushchii lipoprotein kak faktor podavleniia rostaopukholei, povysheniia chisla leikotsitov, uskoreniia deleniia kletok v kul'ture.

Superoxide-generating lipoprotein was isolated and purified from human serum; four intraperitoneal injections of Fe(3+)-activated suprol (150 micrograms/ml) increased rat peripheral blood leukocytes only by 8-10% in 24 h. In 3 days after inoculation of animals with Pliss lymphosarcoma or M-1 sarcoma, similar injections of activated suprol increased leukocyte count up to the numbers in healthy animals. Growth of M-1 sarcoma and Pliss sarcoma was decreased by 31 +/- 4 and 52 +/- 2%, respectively. Activated suprol (15 micrograms/ml) stimulated growth of stationary chicken embryonic cell culture by 52.1%. Activated suprol at concentrations exceeding 50 micrograms/ml lysed all cells in the culture. Cu,Zn-superoxide dismutase suppressed suprol-stimulated proliferation of actively proliferating culture; not activated (native) suprol did not significantly increase leukocyte count, did not suppress tumor growth, and did not stimulate growth of cultured cells. The data suggest an important role of superoxide radicals in these processes. Inhibition of tumor growth by suprol may be associated with tumor DNA degradation by superoxide radicals (tumor DNA is more sensitive to O2- because superoxide dismutase activity is significantly lower in tumor cells versus normal tissues) and increased resistance of the organism due to stimulation of leukopoiesis.