Effect on an iron-chelator on ascorbate-induced cytotoxicity

Area of Science:

• Biochemistry
• Cell Biology
• Toxicology

Background:

• Ascorbate (vitamin C) can exhibit pro-oxidant properties.
• Iron-catalyzed oxidation is a potential mechanism for ascorbate's cytotoxicity.
• Deferoxamine mesylate (DFO) is an iron chelator used to investigate iron's role.

Purpose of the Study:

• To determine if ascorbate-induced cytotoxicity is mediated by iron-catalyzed oxidation.
• To investigate the effect of DFO on ascorbate's cytotoxic effects in different cell lines.
• To explore the role of serum in modulating ascorbate's cytotoxicity.

Main Methods:

• Exposure of HL-60 and T98G cells to sodium ascorbate or ascorbic acid.
• Co-administration of varying concentrations of DFO with ascorbate.
• Assessment of apoptosis markers (cell shrinkage, DNA fragmentation).
• Measurement of oxidation potential and ascorbyl radical intensity.

Main Results:

• Ascorbate induced apoptosis in HL-60 cells, which was enhanced, not inhibited, by DFO.
• Serum significantly inhibited ascorbate-induced cytotoxicity in HL-60 cells.
• DFO had differential effects on ascorbate cytotoxicity in T98G cells (enhancement at low, reduction at high concentrations).
• Ascorbate increased medium oxidation potential, an effect augmented by cells.
• DFO had minimal impact on ascorbyl radical intensity and oxidation potential.

Conclusions:

• Ascorbate can induce cytotoxicity independently of iron-catalyzed oxidation.
• The cellular response to ascorbate and DFO is cell-type dependent.
• Serum components can protect against ascorbate-induced cytotoxicity.
• Iron chelation does not universally prevent ascorbate-induced apoptosis and can sometimes enhance it.