[Cytochrome P-450 and aryl hydroxylase activity in cells of a long-term transplantable tumor].

A functionally active system of microsomal monooxygenases has been found in a long-term transplanted tumor MC-II of C57B1/6j mice. In microsomal fraction of the tumor, one could detect cytochrome P-450 and benzo(a)pyrene hydroxylase (BP hydroxylase) activity. The latter one increased more than 2 times after the animals received 3-MC and aroclor 1254. In in-vitro experiments, the microsomal monooxygenase inhibitors, SKF 525-A and metyrapone, did not affect BP hydroxylation, whereas alpha-naphthoflavone inhibited the enzyme. It is assumed that tumor MC-II contains hemoprotein that is similar to cytochrome P1-450.