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Enhancement of misonidazole cytotoxicity by iron
Abstract:
The toxicity of misonidazole (MISO) to hypoxic Chinese hamster ovary (CHO) cells in serum-free medium is enhanced by Fe(III)-EDTA. Enhancement of MISO cytotoxicity by a factor of 1.6 was seen with 2 microM Fe(III)-EDTA, while 200 microM Fe(III)-EDTA results in sensitization by a factor of 2.0. Treatment of CHO cells with the iron chelator desferal resulted in protection against the hypoxic cytotoxicity in MISO (approximate protection factor of 2.5 with 100 microM desferal). Similar results were obtained with Chinese hamster V79 cells. Fe(III)-EDTA also enhanced binding of [2-14C] MISO to cellular macromolecules while desferal decreased binding of MISO to cellular macromolecules. These results suggest that iron plays an important role in the reductive metabolism of MISO and that modification of the intracellular metal ion status may be a useful approach to modulating the biological effect of nitro compounds.
Insights
Iron enhances misonidazole (MISO) toxicity to hypoxic cells, while iron chelators protect them. Modifying iron levels could alter the biological effects of nitro-based compounds.
Area of Science:
- Cell Biology
- Biochemistry
- Pharmacology
Background:
- Misonidazole (MISO) is a nitroimidazole drug used in cancer therapy.
- Hypoxic conditions in tumors can affect drug efficacy.
- The role of metal ions in MISO's mechanism of action is not fully understood.
Purpose of the Study:
- To investigate the effect of iron, specifically Fe(III)-EDTA, on MISO's toxicity to hypoxic cells.
- To explore the potential of iron chelation in mitigating MISO's cytotoxicity.
Main Methods:
- Utilized Chinese hamster ovary (CHO) and V79 cells under hypoxic conditions.
- Administered varying concentrations of Fe(III)-EDTA to assess enhancement of MISO toxicity.
- Used desferal, an iron chelator, to evaluate protective effects against MISO.
- Measured the binding of radiolabeled MISO to cellular macromolecules.
Main Results:
- Fe(III)-EDTA significantly enhanced MISO cytotoxicity in a dose-dependent manner.
- Desferal provided significant protection against MISO's hypoxic toxicity.
- Fe(III)-EDTA increased MISO binding to cellular macromolecules, while desferal decreased it.
Conclusions:
- Iron plays a crucial role in the reductive metabolism of misonidazole.
- Manipulating intracellular iron levels may be a viable strategy to modulate the biological activity of nitro compounds.
- These findings have implications for optimizing cancer treatment strategies involving MISO or similar drugs.