Activities of free radical metabolizing enzymes in tumours

The activity of enzymatic defences against free radical attack including superoxide dismutase (SOD), catalase, glutathione peroxidase and glutathione reductase have been compared in some experimental animal tumours with the corresponding normal mouse tissues. The activity of SOD in PC6 plasmacytoma and P388 lymphocytic leukaemia was lower than in normal lymphocytes and the activity in a mouse bladder carcinoma (MB) was one-half of that of the normal bladder tissue. Similarly PC6, P388, TLX5 lymphoma and MB showed lower catalase activity than the corresponding normal tissues. The activity of glutathione peroxidase in tumours was in general comparable with that of the normal tissues with the exception of MB, while TLX5, PC6 and P388 contained much lower glutathione reductase activity than normal lymphocytes. The results suggest that it may be possible to selectively destroy certain tumours by peroxidative attack, and that P388 leukaemia would be much more sensitive than L1210 leukaemia to free radical production.