Estrogen synthesis in normal and malignant human endometrium.

The ability of human endometrium to synthesize estrogen from testosterone (T) was investigated. Normal and malignant endometrial specimens were incubated in a complete nutrient medium with 1 muC/ml (approximately 10 pmol/ml) of [3H]T for 20 hrs. Various estrogens: estrone (E1), estradiol (E2), estrone sulfate (E1S), and estradiol-3-sulfate (E2S) were isolated from cultured tissue and medium. The capacity of aromatization, expressed in pmol of estrogen formed/g of tissue, of proliferative endometria was found to be significantly higher than that of secretory endometria (prol. n=12, 0.53 +/- 0.21, vs sec. n=13, 0.15 +/- 0.09, mean +/- s.d., P less than 0.005). In nine cancer endometrial specimens studied, the estrogen produced varied from 0.3 to 15 pmol/g of tissue. These studies represent the first evidence that human endometrium is capable of synthesizing estrogens from delta 4 androgens at a concentration similar to plasma level. The changes of the capacity of aromatization during the two phases of the menstrual cycle indicate that the estrogen synthesis in endometrium is apparently regulated by hormones. The presence of aromatase in cancer endometria may play an important role in promoting the cell growth in estrogen sensitive endometrial cancer.