On the Mechanism of Accumulation of ⁶⁷Ga by Tumors

Abstract

There is strong experimental evidence indicating that a competitive binding of 67Ga³⁺ to Ca²⁺- and Mg²⁺-binding sites rather than a metabolic process is involved in the accumulation of this radioisotope. These observations suggest that in tumors, as well as in other inflammatory and infectious processes, the most important role in ⁶⁷Ga accumulation is played by a higher availability of those binding sites than in normal tissue.

Ionic Competition and 67Ga in Vivo Accumulation

“…The ionic radius of gallium (Ga 3 + ) is 0.62 Â, that of Fe 3 + is 0.64 À, of In 3 + and Sc 3 + is 0.81 À and 1.15 À for La 3 + (9). In the light of the hypothesis of isomorphous ionic replacement the ionic size and the electric charge (valence) are the factors determining the bonding of ions to cell binding-sites (1). In spite of the possibility of steric fitting (11) already demonstrated for some Ga 3 + compounds (1) and which concerns the bonding of ions with sizes different to that of the binding-site in consideration ( Fig.…”

“…In the light of the hypothesis of isomorphous ionic replacement the ionic size and the electric charge (valence) are the factors determining the bonding of ions to cell binding-sites (1). In spite of the possibility of steric fitting (11) already demonstrated for some Ga 3 + compounds (1) and which concerns the bonding of ions with sizes different to that of the binding-site in consideration ( Fig. 2), it seems very likely that in tumor tissue there are binding-sites capable of being occu- pied by cations with a suitable radius ranging from 0.62 Â to 0.81 Ä, and which are able to compete with 6 7 Ga.…”

Colchicine in refractory chronic lymphocytic leukemia

“…More recently, in vitro cell lysis experiments using colchicine at concentrations of from 0.04 mg/ml to 0.1 mg/ml, distinguished the lymphocytes of chronic lymphocytic leukemia and other lymphoid malignancies from benign causes of lymphocytosis (6)(7)(8)(9). The mechanisms for the above differences in lymphocytic tissues has been postulated to be an abnormality in the metabolism of divalent ions (10)(11)(12).…”

201T1 to 67Ga uptake ratio as an indicator for predicting tumour doubling time in human pulmonary neoplasms

“…While the exact mechanism of 201T1 and 67Ga accumulations Correspondence: T. Togawa. Received 9 September 1985;and in revised form, 10 December 1985. into malignant cells still remains unsolved, it is well known that tumour accumulations of 201T1 and 67Ga are associated with potassium, calcium and magnesium metabolism, respectively (Anghileri et al, 1977;Ito et al, 1978), which play an important role in the control of cell transformation and growth (Yang et al, 1971;Davies et al, 1984;Banyard et al, 1985). Therefore, we extended our work in an attempt to confirm the relation between 201T1 to 67Ga uptake ratio and the growth rate of lung cancer, and to evaluate whether quantitative 201T1 and 67Ga scans, clinically simple, available and noninvasive diagnostic tools, lend themselves to prediction of tumour growth rate.…”