Estrogen sulfotransferase is significantly more active in the normal breast cell (e.g., Human 7) than in the
cancer cell (e.g., MCF-7). The data suggest that in
breast cancer sulfoconjugated activity is carried out by another
enzyme, the SULT1A, which acts at high concentration of the substrates. In
breast cancer cells
sulfotransferase (SULT) activity can be stimulated by various
progestins:
medrogestone,
promegestone, and
nomegestrol acetate, as well as by
tibolone and its metabolites. SULT activities can also be controlled by other substances including
phytoestrogens,
celecoxib,
flavonoids (e.g.,
quercetin,
resveratrol), and
isoflavones. SULT expression was localized in
breast cancer cells, which can be stimulated by
promegestone and correlated with the increase of the
enzyme activity. The
estrogen sulfotransferase (SULT1E1), which acts at nanomolar concentration of
estradiol, can inactivate most of this
hormone present in the normal breast; however, in the
breast cancer cells, the
sulfotransferase denoted as SULT1A1 is mainly present, and this acts at micromolar concentrations of E(2). A correlation was postulated among
breast cancer cell proliferation, the effect of various
progestins, and
sulfotransferase stimulation. In conclusion, it is suggested that factors involved in the stimulation of the
estrogen sulfotransferases could provide new possibilities for the treatment of patients with
hormone-dependent breast and
endometrial cancers.