FIGURE 1.

Up-regulation of GADD34, GADD45-α, -β, -γ, GADD153, p21, and TfR1 mRNA levels after incubation of MCF7 cells with the iron chelators DFO and 311. A, MCF7 breast cancer cells were incubated for 24 h/37 °C with control medium or this medium containing the iron chelators DFO (250 μm) or 311 (25 μm). Total mRNA was extracted and then RT-PCR performed. B, GADD45α is up-regulated in a time-dependent manner in response to iron chelators, hypoxia, or low concentrations (5 nm) of the DNA-damaging agent, actinomycin D (Act D). MCF7 cells were incubated for 0, 2, 4, 8, 16, or 24 h/37 °C under standard culture conditions (95% air/5% CO₂) with either: control medium or this medium containing 311 (25 μm) or low concentrations of the DNA-damaging agent, Act D (5 nm), or incubated under hypoxic culture conditions (1% O₂, 94% N₂, 5% CO₂) with control medium only. C, up-regulation of GADD45α and TfR1 (as control) mRNA levels after incubation with DFO or 311 is markedly decreased upon re-incubation with the iron donor, ferric ammonium citrate (FAC, 100 μg/ml). Results shown are typical gels from three experiments, while the densitometry is mean ± S.D. *, p < 0.05; **, p < 0.01; ***, p < 0.001, relative to the control.