QUERCETIN INHIBITS HEAT-SHOCK-PROTEIN INDUCTION BUT NOT HEAT-SHOCK FACTOR DNA-BINDING IN HUMAN BREAST-CARCINOMA CELLS

The flavonoid quercetin inhibits the heat-induced synthesis of heat sh ock proteins (hsps) in a variety of cell lines. To determine whether q uercetin could inhibit hsp expression in breast cancer cells, we used the human breast cancer cell line, MDA-MB-231. Treatment of these cell s with quercetin decreased the heat-induced synthesis of hsp27 and hsp 70. However, inhibition of hsp expression did not correspond with the reduced ability of heat shock transcription factors (HSFs) to bind DNA . Furthermore, while quercetin treatment inhibited HSF2 expression, it only slightly affected HSF1 expression in breast cancer cells. In con trast, quercetin inhibited both HSF DNA-binding activity and HSF expre ssion in HeLa cells. Our studies suggest that quercetin's action is ce ll-type specific, and in breast cancer cells may involve regulation of HSF transcriptional activity, rather than regulation of its DNA-bindi ng activity. (C) 1997 Academic Press.