1Deparments of Nuclear Medicine, Chonbuk National University Medical School, Chonju, Korea. 2Internal Medicine, Chonbuk National University Medical School, Chonju, Korea. 3Institute for Medical Sciences, Chonbuk National University Medical School, Chonju, Korea.
ABSTRACT
PURPOSE: We determined whether the uptake of Ga-67 by cultured cells occur by both transferrin (Tf)-dependent and independent mechanisms and the mechanism and magnitude of its uptake may vary as the degree of expression of the transformed phenotype.
MATERIALS AND METHODS: Uptake of Ga-67 between the tansformed and untransformed cells was compared. Cells were incubated with Ga-67 in either the presence or absence of Tf and with complete medium containing Ga-67 after preincubating with anti-Tf receptor antibodies at 37oC in 8% CO2. Monolayers of cells were washed and trypsinized.
Radioactivity and protein content of the samples were determined.
RESULTS: Uptake of Ga-67 by cultured cells occurred both in Tf-bound and ionic form and was increased with radioactivity and time. The magnitude for the uptake of Tf-bound form was approximately 3 and 6-fold greater than ionic form. In the presence of Tf, uptake of Ga-67 was 2-fold greater in the transformed cells. Conversely, In the absence of Tf, it was 1.5-fold greater in the untransformed cells. Regardless of blocking the Tf receptor by anti-Tf receptor antibodies, a significant amount of intracellular Ga-67 uptake was found.
CONCLUSION: Dual mechanisms exist for the uptake of Ga-67 by cultured cells. The primary important one was the Tf-dependent system. Tf-dependent and independent mechanisms and the magnitude operated oppositely in the transformed cells when compared to their untransformed counterpart.
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