FACTORS INFLUENCING AROMATASE-ACTIVITY IN THE BREAST

Particularly in postmenopausal women, peripheral aromatase appears to be the major source of oestrogens which may encourage the growth of ho rmone-dependent tumours. Studies have therefore been undertaken to det ermine factors which influence biosynthesis of oestrogens within breas t tissues. Aromatase activity was measured in (i) breast cancers by in cubating tumour homogenates with [7alphaH-3]testosterone and character izing the production of radioactively-labelled oestradiol and (ii) bre ast fat by incubation of sub-cellular fractions of fibroblast cell lin es with [1betaH-3]androstenedione and monitoring the formation of (H2O )-H-3. Evidence has been presented that (i) certain treatment regimes for cancer profoundly influence aromatase activity in breast tumours, (ii) aromatase activity is elevated in breast fat associated with mali gnancy and (iii) breast-derived fluids and extracts can markedly affec t aromatase activity in cultured fibroblasts of breast fat.