Regulation of oestradiol 17 beta hydroxysteroid dehydrogenase in breast tissues: the role of growth factors.

Oestradiol 17 beta-hydroxysteroid dehydrogenase (E2DH) is present in normal and malignant breast tissues and regulates the interconversion of oestrone and the biologically active oestrogen, oestradiol. Studies we have previously carried out have indicated that concentrations of oestradiol and the conversion of oestrone to oestradiol are higher in breast tumours than in normal breast tissues. We are currently isolating and characterizing factors produced by breast tumours which are capable of stimulating E2DH (reductive) activity. The production of such factors by breast tumours, which stimulate the conversion of oestrone to oestradiol, would provide a favourable oestrogenic environment to promote tumour growth and may account for the increased concentrations of oestradiol in breast tumours.