The anticancer enzyme DT diaphorase is induced selectively in liver during ascites hepatoma growth.

DT diaphorase catalyzes the transfer of two electrons to quinones to form relatively stable hydroquinones, thus protecting cells from damage by semiquinone production and subsequent superoxide radical formation. A rapid and substantial increase in the activity of DT diaphorase occurs in the cytosolic and microsomal fractions of livers of rats with Zajdela ascites hepatoma under conditions which generally depress the activity of other xenobiotic-metabolizing enzymes. The increase is time-dependent, parallels the increase in the specific activity of DT diaphorase of the growing hepatoma cells, and is limited to the liver. Treatment of rats with hepatoma cytosol results in a rapid increase in liver cytosolic DT diaphorase activity in a dose-dependent manner.