CONTROL OF AROMATASE-ACTIVITY IN BREAST-CANCER CELLS - THE ROLE OF CYTOKINES AND GROWTH-FACTORS

The aromatase complex has a key role in regulating oestrogen formation in normal and malignant breast tissues. Using dexamethasone-treated f ibroblasts, derived from breast tumours, breast tumour cytosol and bre ast tumour-derived conditioned medium (CM) markedly stimulate aromatas e activity. The cytokine, interleukin-6 (IL-6) has been identified as a factor present in CM which is capable of stimulating aromatase activ ity. To examine whether IL-6 may have a role in vivo in regulating bre ast tissue aromatase activity, IL-6 production and aromatase activity in breast tumour and adipose tissue from breast quadrants were examine d. In 5/6 breasts examined so far, aromatase activity was highest in a dipose tissue in the breast quadrant containing the tumour or on which the tumour impinged. There was a significant correlation (P < 0.05, K endall's rank correlation) between IL-6 production and aromatase activ ity in these breast tissues. It is concluded that IL-6 may have an imp ortant role in regulating aromatase activity in breast tissues.