Bioreductive activation of mitomycin C by DT-diaphorase

Biochemistry. 1992 Sep 1;31(34):7879-85. doi: 10.1021/bi00149a019.


The role of DT-diaphorase (DTD, EC in the bioreductive activation of mitomycin C was examined using purified rat hepatic DTD. The formation of adducts with reduced glutathione (GSH), binding of [3H]mitomycin C to DNA, and mitomycin C-induced DNA interstrand cross-linking were used as indicators of bioactivation. Mitomycin C was metabolized by DTD in a pH-dependent manner with increasing amounts of metabolism observed as the pH was decreased from 7.8 to 5.8. The major metabolite observed during DTD-mediated reduction of mitomycin C was 2,7-diaminomitosene. GSH adduct formation, binding of [3H]mitomycin C and mitomycin C-induced DNA interstrand cross-linking were observed during DTD-mediated metabolism. In agreement with the pH dependence of metabolism, increased bioactivation was observed at lower pH values. Temporal studies and experiments using authentic material showed that 2,7-diaminomitosene could be further metabolized by DTD resulting in the formation of mitosene adducts with GSH. DNA cross-linking during either chemical (sodium borohydride) or enzymatic (DTD) mediated reduction of mitomycin C could be observed at pH 7.4, but it increased as the pH was decreased to 5.8, showing the critical role of pH in the cross-linking process. These data provide unequivocal evidence that the obligate two-electron reductase DTD can bioactivate mitomycin C to reactive species which can form adducts with GSH and DNA and induce DNA cross-linking. The use of mitomycin C may be a viable approach to the therapy of tumors high in DTD activity, particularly when combined with strategies to lower tumor pH.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Chromatography, High Pressure Liquid
  • DNA / metabolism
  • Glutathione / metabolism
  • Hydrogen-Ion Concentration
  • Liver / enzymology*
  • Magnetic Resonance Spectroscopy
  • Mitomycin / metabolism*
  • Mitomycins / metabolism
  • NAD / metabolism
  • NAD(P)H Dehydrogenase (Quinone) / metabolism*
  • Oxidation-Reduction
  • Rats
  • Rats, Inbred Strains


  • Mitomycins
  • NAD
  • Mitomycin
  • 2,7-diaminomitosene
  • DNA
  • NAD(P)H Dehydrogenase (Quinone)
  • Glutathione