Comparison of aromatase activity in human prostatic, testicular and placental tissues.
The aromatase enzyme was quantified by the release of tritiated water from [1 beta-3H] androstenedione. Tritiated water was released by the crude homogenates in 4 of 18 samples of benign prostatic hyperplasia tissue and one of 5 samples of prostate carcinoma tissue. However, this apparent aromatase activity was not inhibited by 4-hydroxyandrostenedione (0.5 and 5.0 microM), and none of the particulate fractions (100,000 g pellet) prepared from each of the prostatic tissues exhibited aromatase activity. Particulate fractions from rat ovary (n = 3) and human testes (n = 6) displayed significant aromatase activity (mean values of 9.9 and 0.033 nmol estrone formed/g protein/h, respectively). The testicular aromatase was inhibited by aminoglutethimide, 4-hydroxyandrostenedione and CGS 16949A with IC50 values of 6.4, 0.17 and 0.0017 microM, respectively. These are of a similar order to values obtained with the aromatase enzyme from human placental microsomes (14, 0.43 and 0.0075 microM, respectively).
Rowlands
M G
MG
Drug Development Section, Institute of Cancer Research, Sutton, Surrey, England, U.K.
Davies
J H
JH
Shearer
R J
RJ
Dowsett
M
M
D000735:Androstenedione / Q000378:metabolism; D000818:Animals; D001141:Aromatase / Q000032:analysis*; D047072:Aromatase Inhibitors; D002277:Carcinoma / Q000201:enzymology; D005260:Female; D006801:Humans; D008297:Male; D008861:Microsomes / Q000201:enzymology; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D011467:Prostate / Q000201:enzymology*; D011470:Prostatic Hyperplasia / Q000201:enzymology; D011471:Prostatic Neoplasms / Q000201:enzymology; D051381:Rats; D013737:Testis / Q000201:enzymology*; D014018:Tissue Distribution
D047072:Aromatase Inhibitors; D000735:Androstenedione; D001141:Aromatase