Estradiol Binding By Fibroid Tumors and Normal Myometrium

The specific, high affinity binding of estradiol in a tissue determines its capacity to retain the hormone and indicates the degree to which the target tissue is sensitive to the hormoneʼs action. The soluble fractions obtained from homogenates of normal and fibroid human myometria were incubated at 4§ with estradiol-17β,6,7-H, then treated with Florisil (60/100 mesh), and the bound radioactive estradiol quantitated in the supernatants after centrifugation. In the presence of 10-M estradiol, cytoplasmic protein from 200 mg of tissue, either normal myometrium or leiomyoma, binds approximately 25% of the added radioactivity. Fibroid tumors bind approximately 20% more estradiol per milligram of cytoplasmic protein than does the normal myometrium of the same organ. These data are consistent with the observation that certain fibroid tumors are estrogen-sensitive neoplasms.