17-BETA-HYDROXYSTEROID DEHYDROGENASE AND AROMATASE-ACTIVITY IN BREAST FAT FROM WOMEN WITH BENIGN AND MALIGNANT BREAST-TUMORS

The activity of 17.BETA.-hydroxysteroid dehydrogenase and aromatase was studied in adipose tissue taken from women aged between 22 and 83 yr with benign or malignant breast lesions. The benign and malignant groups showed no significant differences in the mean activities of either of the enzymes studied. Under the experimental conditions used, the rate of conversion of estrone to estradiol varied markedly between subjects (6-169 ng estradiol/mg protein per h), and there was a positive correlation between estrone reduction and the total body wt of the tissue donor. In contrast, although the apparent Km for estradiol (0.1-2.6 .mu.mol/l) was lower than that for estrone (9-14 .mu.mol/l) the maximum velocity for estrone production was very low (10-50 pmol/mg protein/h), and there was no obvious correlation with the age or body wt of the tissue donor. Aromatase activity in breast fat was at the lower end of the normal range of activity previously reported for abdominal adipose tissue, and there was no correlation between estrone production and age or body wt.