Preliminary studies of aromatase in human neoplastic endometrium.

: The capacity of aromatization in 15 neoplastic human endometrial specimens was investigated. Viable tissue fragments were incubated with [3H]testosterone (10 nM) at 37C for 20 hours. Various estrogens were isolated from the incubated tissues and medium. The mean value of estrogen synthesized in 12 cases of endometrial adenocarcinoma (16.0 +/- 11, means +/- SD fmol/mg protein), is approximately two and five times higher than that of proliferative and secretory endometria, respectively. The highest capacity was found in three mixed mullerian tumors (means = 145 fmol/mg protein). These findings indicate that the malignant endometria, in particular the mixed mullerian tumors, are able to synthesize estrogen in a capacity higher than that in normal endometria. Endometrial aromatase may play an important role in promoting cell growth in estrogen-sensitive tumors.