Growth-stimulating effect of transferrin on a hybridoma cell line: relation to transferrin iron-transporting function.
The relation of the growth-stimulating capacity of transferrin to its iron-transporting function was investigated in mouse hybridoma PLV-01 cells cultivated in a chemically defined medium. The cells were precultivated in protein-free medium supplemented either with ferric citrate (cells with a high intracellular iron level) or with iron-saturated transferrin (cells with a low intracellular iron level). Iron uptake was monitored after the application of 59Fe-labeled ferric citrate or pig transferrin. Cultivation of the cells at the optimum growth-stimulating concentration (500 microM) of ferric citrate resulted in an intracellular iron level about 100-fold higher than that of cells cultivated at the optimum transferrin concentration (5 micrograms/ml). Replacement of pig transferrin with bovine transferrin resulted in similar intracellular iron levels, but the growth-stimulating effect of bovine transferrin was more than one order of magnitude lower. Cells with a high intracellular iron level grew equally well when cultivated with iron-saturated transferrin or with apotransferrin + deferoxamine (2 micrograms/ml). On the other hand, cells with a low intracellular iron level required iron-saturated transferrin for further growth and apotransferrin + deferoxamine was ineffective. The results suggest that transferrin can act as a cell growth factor only in the iron-saturated form. However, several findings of this work indicate that supplying cells with iron cannot be accepted as the full explanation of the transferrin growth-stimulating effect.
Kovár
J
J
Institute of Molecular Genetics, Czechoslovak Academy of Sciences, Praha.
Franĕk
F
F
D000818:Animals; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media; D006825:Hybridomas / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D013552:Swine; D014168:Transferrin / Q000378:metabolism / Q000494:pharmacology*
D003470:Culture Media; D014168:Transferrin; D007501:Iron