Jc. Le Bail et al., Effects of phytoestrogens on aromatase, 3 beta and 17 beta-hydroxysteroid dehydrogenase activities and human breast cancer cells, LIFE SCI, 66(14), 2000, pp. 1281-1291
Isoflavones and others phytoestrogens have been suggested to be anticarcino
genic. Anti-aromatase, antiestrogenic or antiproliferative actions of these
compounds have been postulated and related to the observation that there i
s a reduced incidence of breast cancer associated with diet. In this study,
we explored some mechanisms by which they can exert cancer-preventive effe
cts. Phytoestrogens were tested for estimating anti-aromatase, anti-3 beta-
hydroxysteroid dehydrogenase Delta(5)/Delta(4) isomerase (3 beta-HSD) and a
nti-17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activities in human
placental microsomes, We found that isoflavonoids and compounds which prese
nted the phenolic B ring in the 3 position on the pyran ring preferentially
inhibited SP-HSD and/or 17 beta-HSD activities than aromatase activity. We
also evaluated their interactions with the estrogen receptor using a stabl
y transfected human breast cancer cell line (MVLN). On the other hand phyto
estrogens were evaluated for their effects on the proliferation in estrogen
-dependent (MCF-7) and independent (MDA-MB231) human breast cancer cells. W
e established a relationship structure-activity and determined regions or/a
nd substituents essential for these different activities. However, at high
concentrations it seems that some phytoestrogens exert their protection aga
inst breast cancer through other estrogen-independent mechanisms.