Dependence of nucleic acid degradation on in situ free-radical production by adriamycin

Biochemistry. 1993 Dec 7;32(48):13156-61. doi: 10.1021/bi00211a026.

Abstract

Adriamycin (Adr) is one of the most powerful antitumor drugs. Its therapeutic effect may be due to its cyclic reduction-oxidation and, thus, generation of oxygen radicals. Using the spin-trap 5,5'-dimethyl-1-pyrroline N-oxide (DMPO) and EPR we have demonstrated that in an enzymatic system consisting of NADPH, NADPH-cytochrome P-450 reductase, and Fe(EDTA)2 Adr stimulates formation of .OH radicals in the presence of DNA or RNA with equal efficiency. Incubation of nucleic acids in the Adr-dependent reaction generating .OH radicals resulted in extensive degradation of double- and single-stranded DNA, but did not effect RNA. In contrast, both DNA and RNA were effectively destroyed in a footprinting system, ascorbate-Fe(EDTA)2-H2O2, which generates .OH radicals in massive quantities. Fluorescence assays indicated that Adr forms stable complexes with ds- and ss-DNA but reacts only slightly with RNA. We conclude that the formation of Adr-nucleic acid complex is necessary for .OH radical-mediated cleavage of the latter, and thus, Adr may be regarded as a chemical nuclease acting in situ.

MeSH terms

  • DNA / chemistry*
  • DNA Damage*
  • Doxorubicin / chemistry*
  • Free Radicals
  • Hydroxides / chemistry
  • Oxygen / chemistry
  • RNA / chemistry*

Substances

  • Free Radicals
  • Hydroxides
  • RNA
  • Doxorubicin
  • DNA
  • Oxygen