Direct effect of Taxol on free radical formation and mitochondrial permeability transition

Gabor Varbiro, Balazs Veres, Ferenc Gallyas, Balazs Sumegi

Research output: Contribution to journalArticle

173 Citations (Scopus)

Abstract

To elucidate the potential role of mitochondria in Taxol-induced cytotoxicity, we studied its direct mitochondrial effects. In Percoll-gradient purified liver mitochondria, Taxol induced large amplitude swelling in a concentration-dependent manner in the μM range. Opening of the permeability pore was also confirmed by the access of mitochondrial matrix enzymes for membrane impermeable substrates in Taxol-treated mitochondria. Taxol induced the dissipation of mitochondrial membrane potential (ΔΨ) determined by Rhodamine123 release and induced the release of cytochrome c from the intermembrane space. All these effects were inhibited by 2.5 μM cyclosporine A. Taxol significantly increased the formation of reactive oxygen species (ROS) in both the aqueous and the lipid phase as determined by dihydrorhodamine123 and resorufin derivative. Cytochrome oxidase inhibitor CN-, azide, and NO abrogated the Taxol-induced mitochondrial ROS formation while inhibitors of the other respiratory complexes and cyclosporine A had no effect. We confirmed that the Taxol-induced collapse of ΔΨ and the induction of ROS production occurs in BRL-3A cells. In conclusion, Taxol-induced adenine nucleotide translocase-cyclophilin complex mediated permeability transition, and cytochrome oxidase mediated ROS production. Because both cytochrome c release and mitochondrial ROS production can induce suicide pathways, the direct mitochondrial effects of Taxol may contribute to its cytotoxicity.

Original languageEnglish
Pages (from-to)548-558
Number of pages11
JournalFree Radical Biology and Medicine
Volume31
Issue number4
DOIs
Publication statusPublished - Aug 15 2001

Keywords

  • Apoptosis
  • Cultured cells
  • Free radicals
  • Mitochondria
  • Permeability transition
  • ROS
  • Taxol

ASJC Scopus subject areas

  • Biochemistry
  • Physiology (medical)

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