Estrogen sulfatase (ES) and
estrogen sulfotransferase (ESFT) activities were measured in a group of primary
breast tumors. The mean value of ES activities, measured in 66
breast tumor specimens, was 0.9 nmol of
estrone formed from
estrone sulfate/mg tissue
protein per hr regardless of the
hormone receptor status of the specimen. However, the average value of the ESFT activity, expressed in nmol of
estradiol-3-sulfate (E2S) formed from
estradiol (E2)/mg of cytosol
protein per hr, was found to be significantly higher in ER +/PGR +
tumors (n = 26, 0.18 +/- 0.15, means +/- SD) than in ER -/PGR -
tumors (n = 31, 0.08 +/- 0.06, P less than 0.005). Normal breast tissues also contain ES and ESFT but the activities were lower than those in
tumors. When fresh
breast tumor tissue fragments were incubated with radioactive E2 (0.4 nM) and E2S (3 nM) separately, E2 was not sulfurylated appreciably while E2S was extensively hydrolyzed to free
estrogens indicating that the combined effect of ES and ESFT in
breast tumor is favored towards the hydrolysis of
estrogen sulfate. These results imply that the circulating
estrogen sulfate could be utilized as the precursor of active
estrogen to promote the cell growth in
hormone sensitive
tumors.