Uptake of Gallium-67 in Transfected Cells and Tumors Absent or Enriched in the Transferrin Receptor

Gallium-67 has been a controversial tumor-imaging agent in nuclear medicine for decades. This controversy centers on why tumors are variable in gallium-avidity, whether 67Ga uptake is a transferrin-independent or dependent process, and whether tumors and nor mal tissues differ in mechanism of uptake. If the factors that control uptake of 67Ga were understood better, then efforts to improve oncologie imaging with 67Ga by increasing the tumor activity, or by decreasing the background, may be warranted. Methods: Conven tional systems for evaluating the mechanism and control of 67Ga uptake have significant limitations. We have endeavored to circum vent these by developing a pair of transfected cell lines. One cell line has no transferrin receptor. In the other, the human transferrin receptor has been restored by transfection and is over-expressed constitutively, without the necessity to manipulate factors such as cell growth or iron content. The uptake of 67Ga,both as a citrate sal