STIMULATION OF PS2 EXPRESSION BY DIET-DERIVED COMPOUNDS

Epidemiological studies suggest a lowered risk of hormone-dependent ca ncers among vegetarians, but the basis for this association remains un clear. Vegetables and fruits contain certain compounds,which can be co nverted to biologically active hormone-like substances, such as lignan s and isoflavones, by intestinal flora. The interaction of these compo unds with endogenous hormones may be a novel, diet-dependent mechanism in cancer prevention. To explore this possibility, we developed a rap id, specific assay system to screen for compounds with estrogen-like a ctivity in tissue culture. We utilized the estrogen receptor-positive breast cancer cell MCF-7 and monitored the expression of the estrogen- responsive protein pS2 by Northern blots. Our results indicated that t he phenolic compounds daidzein, equol, nordihydroguaiaretic acid, ente rolactone, and kaempferol were able to elicit an estrogen-like respons e, while quercetin and enterodiol were not.