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Nitroxide TEMPOL impairs mitochondrial function and induces apoptosis in HL60 cells

E Monti1, R Supino, M Colleoni

  • 1Department of Structural and Functional Biology, University of Insubria, Varese, Italy. elena.monti@unimi.it

Journal of Cellular Biochemistry
|August 31, 2001
PubMed

Insights

The antioxidant TEMPOL triggers cancer cell death by damaging mitochondria, impacting oxidative phosphorylation and glutathione levels. This suggests TEMPOL may enhance cancer treatments by sensitizing cells to other drugs.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Pharmacology

Background:

  • Mitochondria are crucial in apoptosis, acting as both sources and targets for free radicals.
  • The piperidine nitroxide TEMPOL is known to induce apoptosis in tumor cells via free radical mechanisms.

Purpose of the Study:

  • To investigate the specific mitochondrial effects of TEMPOL in human promyelocytic leukemia (HL-60) cells.
  • To elucidate the role of mitochondrial dysfunction in TEMPOL-induced oxidative stress and apoptosis.

Main Methods:

  • Exposure of HL-60 cells to TEMPOL for 24 hours.
  • Assessment of intracellular and mitochondrial glutathione levels.
  • Evaluation of oxidative phosphorylation and mitochondrial membrane potential.
  • Analysis of TEMPOL's specific targeting of respiratory chain complexes.

Main Results:

  • TEMPOL decreased intracellular and mitochondrial glutathione pools.
  • Oxidative phosphorylation was impaired, and mitochondrial membrane potential decreased.
  • TEMPOL specifically targeted complex I of the respiratory chain, with minimal effects on complexes II and IV.

Conclusions:

  • Mitochondrial alterations, including glutathione depletion and impaired oxidative phosphorylation, are key effects of TEMPOL.
  • TEMPOL's targeting of respiratory complex I contributes to its pro-apoptotic effects.
  • TEMPOL may sensitize tumor cells to cytotoxic agents, offering potential therapeutic strategies.

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