Modulation of oestrone sulphate formation and hydrolysis in breast cancer cells by breast cyst fluid from British and Hungarian women

Women with gross cystic breast disease may have an increased risk of breast cancer. In this study the ability of breast cyst fluid (BCF), obtained fro m British or Hungarian women,to modulate oestrone sulphate (E1S) formation or hydrolysis, has been examined. For this, oestrogen receptor-positive (ER +) MCF-7 or MDA-MB-231 (ER-) breast cancer cells were employed. the formati on and hydrolysis of EIS was measured using radiometric techniques. BCF fro m British and Hungarian women mainly inhibited E1S hydrolysis in MCF-7 cell s while stimulating hydrolysis in MDA-MB-231 cells; The extent of inhibitio n or stimulation of EIS hydrolysis in these; cells was related to the Na+/K + ratio of the BCF. There was a significant inverse relationship between th e extent to which BCF samples inhibited hydrolysis in MCF-7 cells and stimu lated it in MDA-MB-231 cells. BCF stimulated E1S formation MCF-7 cells whil e inhibiting formation in MDA-MB-231 cells. No difference in the ability of BCF from British or Hungarian women to inhibit or stimulate E1S hydrolysis was detected in ER+ or ER- breast cancer cells, in contrast, BCF from Brit ish women stimulated E1S formation in ER+ cells (median 82%) to a significa ntly greater extent (P < 0.01) than BCF from Hungarian women (median 33%). The role that E1S has in breast cancer development remains unclear. The gre ater stimulation of E1S formation by BCF from British women, who have a hig her risk of breast cancer than Hungarian women, suggests that it may act as a storage form of oestrogen within cells that can he activated by oestrone sulphatase. (C) 2000 Cancer Research Campaign.