Fv. So et al., INHIBITION OF PROLIFERATION OF ESTROGEN RECEPTOR-POSITIVE MCF-7 HUMANBREAST-CANCER CELLS BY FLAVONOIDS IN THE PRESENCE AND ABSENCE OF EXCESS ESTROGEN, Cancer letters, 112(2), 1997, pp. 127-133
The flavonoids are a group of naturally-occurring, low molecular weigh
t compounds that are widespread in plants. Representatives of several
different classes of flavonoids were tested for their effects on the p
roliferation of an estrogen receptor-positive human breast cancer cell
line, MCF-7. The IC(50)s (concentration at which cell proliferation w
as inhibited by 50%), based on [H-3]thymidine incorporation, ranged fr
om 4.2 to 18.0 mu g/mL. The cells were viable at these concentrations.
The possibility that flavonoids may block cell proliferation by bindi
ng to the estrogen receptor was explored. The cells were depleted of e
ndogenous steroids and incubated with individual flavonoids at their I
C50 concentration. Half of the cells were exposed to an excess concent
ration of 17 beta-estradiol to see if this affected antiproliferation
by the flavonoids. Of the flavonoids tested, only the inhibition of ce
ll proliferation by genistein was reversed with the addition of excess
, competing estrogen. Baicalein, galangin, hesperetin, naringenin and
quercetin apparently exert their antiproliferative activity via some o
ther mechanism. (C) 1997 Elsevier Science Ireland Ltd.