[Estrogen biosynthesis in human uterine myoma tissue. The distribution of androstenedione aromatase activity in uterine myoma tissue]

Abstract

Although it is well known that the development of uterine myoma is influenced by estrogen, the details of its remain unknown. In this study, estrogen biosynthesis (androstenedione aromatase activity) was investigated in the myoma tissue (the central, surface and middle parts of the tumor) and in the myometrial tissue of the same uterus (5 cases). The tissue homogenate (500 mg w. w.) was incubated with [6,7-3H]-androstenedione (100pmol) and NADPH (1.5mg) at 37 degrees C for 1h in air. After stopping the enzyme reaction with ethyl acetate, [4-14C]-estrone and [4-14C]-estradiol-17 beta (10,000dpm, 250 micrograms, respectively) were added to the incubated sample. The sample extracted with ethyl acetate was subjected to Bio-Rad AG1-X2 column, thin layer chromatography and co-crystallization to constant specific activity and 3H/14C ratio. Estrogen formed in the incubated sample was calculated from the 3H/14C ratio of the final crystal. The myoma tissues (14 samples) converted from androstenedione to estrone (36-466 fmol/h/g), while the myometrial tissues of the same uterus did to a lesser extent (22-78 fmol/h/g), while the myometrial tissues of the same uterus did to a lesser extent (22-78 fmol/h/g). Thus, aromatase activity was significantly higher in the myoma tissue rather than in the myometrial tissue of the same uterus. Less estradiol was formed than estrone in both tissues. The distribution of aromatase activity in the tumor was also investigated, and it was found that the enzyme activity tends to become greater away from the center and towards the surface of the tumor. These results suggest that aromatase activity for androgen contributes to the development of uterine myoma.