INCREASED UPTAKE OF IODIDE BY HORMONE-RESPONSIVE COMPARED TO HORMONE-INDEPENDENT MAMMARY-TUMORS IN GR MICE

The uptake of 125I by transplanted hormone responsive (HR) or hormone independent (HI) mammary tumors, normal mammary tissue and skeletal muscle was compared in GR mice. The uptake of 125I by HR mammary tumors in mice treated with progesterone and estrone (P + E) was about 20 times greater than the uptake of 125I by HI mammary tumors in mice not treated with P + E. This difference in uptake of 125I by HR and HI mammary tumors could not be attributed to the difference in the hormonal status of the mice, since uptake of 125I was also low in HI tumors in mice receiving P + E treatment. The uptake of 125I by HR mammary tumors was reduced by the simultaneous injection of an excess of nonradioactive iodide or perchlorate. Uptake of 125I by normal mammary tissue and skeletal muscle was similar in all groups of tumor-bearing mice, and was not influenced by the presence of an excess of nonradioactive iodide or perchlorate. The possible clinical significance of these findings is discussed.