TRANSFERRIN-MEDIATED UPTAKE OF GA-67 BY EMT-6 SARCOMA .1. STUDIES IN TISSUE-CULTURE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 20  (8) , 837-842
Abstract
The in vitro uptake of 67Ga was studied by exponentially growing [mouse] EMT-6 sarcoma cells in long-term tissue culture. In this system, transferrin addition to the medium was required before an appreciable cellular uptake of 67Ga occurred. The transferrin effect was complex, with an initial stimulation to a peak cell-to-medium ratio of 8-10:1 at low concentrations of transferrin (0.2 mg/ml), followed by gradual uptake decline as transferrin in the medium was increased further. EMT-6 tumor-cell uptake of 67Ga was probably mediated by a specific cellular receptor for transferrin. Scatchard analysis of the EMT-6 cellular binding of human transferrin labeled with 125I indicated a cellular receptor with affinity for transferrin of 5 .times. 106 l/mol and abundance of 500,000 receptors/cell. Over the experimental transferrin concentration range in the medium, observed 67Ga uptake closely correlated with formation degree of 67Ga-labeled transferrin and the transferrin fraction bound to the cellular receptor (N = 69, r [correlation coefficient] = 0.86, P < 0.0001). [The use of 67Ga for the imaging of a variety of epithelial and lymphoreticular neoplasms was discusssed.].