Correlation of estrogen sulfotransferase activity and proliferation in normal and carcinomatous human breast. A hypothesis.

BACKGROUND Sulfotransferases are present in normal and cancerous human breast tissues. The purpose of this article is to present a hypothetical correlation of sulfotransferase activity with proliferation in breast cancer. MATERIALS AND METHODS Sulfotransferases were evaluated in breast cancer cells by determining the transformation of non-conjugated estrogens to the sulfates. Proliferation was evaluated by the action on cell growth or the size of a transplanted tumor. The effect was obtained using the progestins: nomegestrol acetate, promegestone, and medrogestone, as well as tibolone and its metabolites at concentrations of 5 x 10(-5) to 5 x 10(-9) M. RESULTS A possible correlation of sulfotransferase activity stimulation and cell growth inhibition provoked by the various progestins used, or by tibolone and its metabolites was shown. CONCLUSION It is suggested that the antiproliferative effect of these compounds could be related to the decrease of bioactive estradiol by the formation of its biologically inactive sulfate as a consequence of the stimulatory effect by the various progestins or tibolone on sulfotransferase activity.