Endocrinology, Vol 110, 2177-2182, Copyright © 1982 by Endocrine Society
Specific cytotoxicity of 16 alpha-[125I]iodoestradiol for estrogen receptor-containing breast cancer cells
DA Bronzert, RB Hochberg and ME Lippman
We attempted to induce specific killing of estrogen receptor-containing
breast cancer cells using estradiol coupled to a high specific activity
gamma emitting isotope of iodine. MCF-7 human breast cancer cells were
incubated with 16 alpha-[125I]iodoestradiol alone ([125I]E2), or with 16
alpha-[125I]iodoestradiol plus 100-fold excess 17 beta-estradiol (E2), and
then viably frozen. After 8 weeks, the [125I]E2 exposed cells and the [125
I]E2 plus E2 exposed cells were 10% and 77% of controls, respectively. When
the breast cancer cell line MDA-MB-231 which does not contain estrogen
receptors was used, the rate of cell death was similar to the competed
MCF-7 cells. When specific cytotoxicity was compared using a cloning
technique, nearly a 5 log reduction in surviving cell fraction was seen
with [125I]E2, as compared to identical cells treated with [125I]E2 plus
competitor. This technique shows promise for selecting a population of
cells with defects in their estrogen receptor and in studying subcellular
hormone interactions.
