Ceruloplasmin promotes iron uptake rather than release in BT325 cells

This study was initiated to investigate the mechanism of ceruloplasmin (CP)-mediated iron release from brain cells using BT325 cells (a glioblastoma cell line); however, negative results were obtained. The BT325 cells were preloaded with 1 μM59Fe2+in sucrose (pH 5.8) for 60 min, and then with CP (0-300 μg/ml) for 30 min at 37°C. The addition of CP, either at low (25 μg/ml) or high (300 μg/ml) concentrations, did not lead to a significant change in iron release from ironloaded BT325 cells. No significant difference in total iron of cells was found between all CP treated groups and the control (P>0.05). Although apotransferrin (apoTf) was shown to have a role in iron release from the cells, the effect of apoTf was not significantly affected by the addition of different concentrations of CP. When the cells were incubated with 1 μM59Fe2+in the presence of varying amounts of CP for 30 min at 37°C, it was found that CP increased iron uptake. The total iron uptake by BT325 cells in CP treatment groups (25, 75, 150, 300 μg/ml) was significantly higher than that in the control (no CP addition) (all P<0.01). Furthermore, in contrast to our expectation, CP was shown to promote significantly iron uptake in not only iron-sufficient but also iron-deficient cells. These results showed that CP had a role in iron uptake rather than release in BT325 cells.