Subcellular concentrations of estrone, estradiol, androstenedione and 17β-hydroxysteroid dehydrogenase (17-β-OH-SDH) activity in malignant and non-malignant human breast tissues

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Abstract
Total and subcellular (cytosol and nuclear) concentrations of estrone (E1), estradiol (E2), and androstenedione were determined in non-malignant (n = 61) and malignant (n = 65) human breast tissues obtained from post-menopausal women. The 17β-hydroxysteroid dehydrogenase (17 β-OH-SDH) activity was determined in 800g supernantant fraction. Total estrogens, E, and E2 levels and 17β-OH-SDH activity were significantly (p < 0.005, 0.0005, 0.001, respectively) higher in malignant than In non-malignant breast tissues. We failed to observe significant changes in subcellular steroid concentrations or enzyme activity associated with patients' obesity or tumor estrogen receptor status. When the steroid levels were analyzed in relation to clinical staging of the disease, nuclear contents of estradiol were significantly higher (p < 0.005) In Stage-IV patients than in those with less advanced disease (Stages I to III). 17β-OH-SDH activity was significantly (p < 0.001) lower in patients with advanced disease than in those with relatively less advanced (Stages I to III) disease and was positively correlated with tissue concentration of androstenedione. Our present data indicate that differential intracellular metabolism of steroid hormones may have some influence on availability of estradiol at nuclear sites. In postmenopausal women, local intercon version of estrogens may provide sufficient estrogenic stimulus to enhance the growth and progression of breast tumors.