Differential hepatic response of 65Zn distribution between mice bearing experimental tumor and inflammation

Discriminative detection of tumor and inflammation was tried by radio-imaging of hepatic uptake of 65Zn. This closely related to the level of metallothionein (MT) and reflected the extent of tumor growth in mice and rats transplanted with experimental tumor. The elevation of 65Zn distribution in liver of experimental tumor-bearing mice was inhibited by treatment with Zn-deficient diet, while stimulated by dexamethasone. This stimulation occurred 2 days after tumor transplantation, at which time 67Ga-citrate could not image the tumor. On the other hand, hepatic distribution of 65Zn was also elevated in mice by inducing experimental abscess, although the effect of both treatments on this elevation was different from the case of tumor; the elevation was inhibited by treatment with dexamethasone. These results suggest that radio-imaging of hepatic Zn uptake with a short-life gamma emitting isotope such as 69mZn with use of dexamethasone, if required, may be useful for a preliminary test to detect early-stage malignant disease.