SUPPRESSIVE EFFECTS ON CANCER CELL-PROLIFERATION OF THE ENHANCEMENT OF SUPEROXIDE-DISMUTASE (SOD) ACTIVITY ASSOCIATED WITH THE PROTEIN-BOUND POLYSACCHARIDE OF CORIOLUS-VERSICOLOR QUEL

The protein-bound polysaccharide of Coriolus versicolor QUEL (PS-K) ex presses superoxide dismutase (SOD) mimicking activity. Examination was made of the suppressive effects of PS-K on cancer cell lines cultured in vitro. SOD activity of incorporated PS-K was 5.88 u/mg in LLC-WRC- 256 (Walker 256 fibrosarcoma) cells and 4.73 u/mg in NRK-49F (rat norm al kidney fibroblast) cells. SOD activity in both cell types was enhan ced about 7-8 times that of the original PS-K PS-K was not incorporate d into H4-11-E or H4-11-E-C3 (rat hepatoma) cells. SOD activity of 1 m g/ml PS-K incubated with cell homogenates of LLC-WRC-256 cells for 6 h ours increased from 0.68 mu/mg to 1.35 mu/mg. SOD activity of PS-K 1 m g/ml in 0.05 M phosphate buffer incubated with 50 muM NADPH increased from 0.68 mu/mg to 1.38 mu/mg. The consumption of NADPH at the same co ncentration was confirmed spectrophotometically by incubation with PS- K The mechanism for the enhancement of SOD activity associated with PS -K is considered to be collaboration with NADPH as an electron donor i n the cytoplasm of cancer cells whose SOD and coupling enzyme activiti es are significantly lower than in normal cells.