Concentration-dependent effect of iron on gamma-linolenic acid toxicity in ZR-75-1 human breast tumor cells in culture.

Polyunsaturated fatty acids are cytotoxic to ZR-75-1 human breast tumor cells in culture. This effect may be potentiated by the simultaneous addition of iron. When cytotoxicity was measured in the presence of different concentrations of both gamma-linolenic acid and ferrous chloride there was an increase in cell death above concentrations of 9 microM and 0.05 microM, respectively. The potentiation of the effects of 18:3n-6 at low concentrations by the simultaneous addition of Fe(II) ions supports the contention that an alteration in the intracellular Fe(II)/Fe(III) ratio is necessary to promote autocatalytic lipid peroxidation.