Superoxide dismutase activity in 1,2-dimethylhydrazine-induced rat colon adenocarcinoma.

1,2-Dimethylhydrazine-induced large bowel tumors in adult male noninbred Holtzman rats contained greatly elevated levels of copper-zinc-containing superoxide dismutase (Cu-Zn SD) activity when compared to levels in normal intestinal tissue but nearly equal levels of manganese-containing superoxide dismutase (Mn SD) activity. Inasmuch as normal intestinal tissue contains many cell types, SD activities were also measured and compared in isolated intestinal epithelial cells. When compared to the activities in villus cells, Cu-Zn SD activity was greatly increased, whereas Mn SD activity was greatly reduced in tumor cells. The SD activity of tumor cells most nearly resembled that of isolated intestinal crypt cells.