Research Library
Genistein inhibits growth of estrogen-independent human breast cancer cells in culture but not in athymic mice.
Authors: Santell RC; Kieu N; Helferich WG
Source: J Nutr 2000 Jul;130(7):1665-9
The studies presented were conducted to assess the effect of the soy
isoflavone genistein on proliferation of estrogen-independent human
breast cancer cells (MDA-MB-231) in vitro and in vivo. Genistein (20
mcmol/L) inhibited cell proliferation in vitro by approximately 50%.
Cell cycle progression was blocked in G(2)/M with 40 and 80 mcmol/L
genistein. To evaluate the effect of dietary genistein on tumor
growth in vivo, genistein was fed to female athymic mice inoculated
with MDA-MB-231 cells. After solid tumor masses had formed, mice were
fed genistein at a dose (750 mcg/g AIN-93G diet), shown to produce a
total plasma genistein concentration of approximately 1 mcmol/L. This
dose of genistein did not significantly (P > 0.05) alter tumor
growth. Studies were then conducted to assess the effect of dietary
genistein on initial tumor development and growth. Genistein (750
mcg/g AIN-93G diet), fed 3 d before cells were inoculated into mice,
did not significantly (P > 0.05) inhibit tumor formation or
growth. The plasma concentration of genistein in mice fed this dose
of dietary genistein (750 mcg/g AIN-93G diet) does not appear
sufficient to inhibit tumor formation or growth. Dietary genistein at
750 mcg/g AIN-93G diet does not inhibit tumor formation or growth.
Additional studies were conducted to determine the effect of dietary
dosages ranging from 0 to 6000 mcg/g AIN-93G diet on plasma genistein
concentration. Plasma genistein concentration increased in a
dose-dependent manner up to 7 mcmol/L at 6000 mcg/g AIN-93G diet.
These data suggest that although genistein inhibits cancer cell
growth in vitro, it is unlikely that the plasma concentration
required to inhibit cancer cell growth in vivo can be achieved from a
dietary dosage of genistein.