Effect of the DpT analogs compared with DFO and 311 on ⁵⁹Fe mobilization and cellular ⁵⁹Fe uptake from ⁵⁹Fe-Tf in SK-N-MC neuroepithelioma and M109 cells. (A) Effect of chelators on ⁵⁹Fe mobilization from prelabeled SK-N-MC neuroepithelioma cells. Cells were prelabeled with ⁵⁹Fe-Tf (0.75 μM) for 3 hours at 37° C, washed, and then reincubated for 3 hours at 37° C in the presence of medium alone (control) or medium containing the chelators (25 μM). (B) Effect of the chelators at preventing ⁵⁹Fe uptake from ⁵⁹Fe-Tf by SK-N-MC cells. Cells were incubated for 3 hours at 37° C in media containing either ⁵⁹Fe-Tf (0.75 μM) alone (control) or ⁵⁹Fe-Tf (0.75 μM) and the chelators (25 μM). After this incubation, the cells were washed and incubated with pronase (1 mg/mL) for 30 minutes at 4° C to measure internalized ⁵⁹Fe.^13,14  (C) Effect of the chelators on ⁵⁹Fe mobilization from prelabeled M109 cells as a function of chelator concentration. M109 cells were prelabeled as described for panel A, then reincubated with the chelator (0.2-25 μM) for 3 hours at 37° C. (D) Effect of the chelators at preventing ⁵⁹Fe uptake from ⁵⁹Fe-Tf by M109 cells as a function of chelator concentration. M109 cells were incubated with ⁵⁹Fe-Tf (0.75 μM) in the presence of the chelators (0.2-25 μM) for 3 hours at 37° C. Cells were washed and incubated with pronase as described for panel B. Results are expressed as the mean ± SD of 3 replicates in a typical experiment of 3 performed.