Human serum transferrin cobalt complex: stability and cellular uptake of cobalt.
Transferrin (Tf) receptor expression is up-regulated on tumour cells. The human serum iron transport protein transferrin (Tf) can bind to many metals including gallium and cobalt. Cobalt has a positron-emitting isotope with a half-life of 18 h and would thus be a useful isotope for imaging purposes. This study has examined the stability of the Co-Tf in the presence of serum and albumin and the uptake of radioactive Co from Co-Tf by tumour cells. Dialysis of 57Co-Tf with serum or with apo-Tf resulted in loss of most 57Co from the complex. The time course of Co uptake from cells incubated with Co-Tf showed an initial rapid association with cells, then a slower rate of accumulation, that is, a similar uptake profile to that of iron. Competition and displacement experiments showed that uptake specifically occurred by interaction with Tf receptors.
Smith
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TA
PET Unit, Department of Biomedical Physics and Bioengineering, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK. t.smith@biomed.abdn.ac.uk
D003035:Cobalt / Q000097:blood*; D003287:Contrast Media; D006801:Humans; D014168:Transferrin / Q000378:metabolism*
D003287:Contrast Media; D014168:Transferrin; D003035:Cobalt