Summary We investigated the effect of the flavonoid quercetin (Q) on the proliferation of the ovarian cancer cell line OVCA 433. Growth experiments demonstrated that Q exerted a reversible dose-dependent inhibition of cell proliferation in the range of concentrations between 10 nm and 10 M. Two other flavonoids tested, rutin and hesperidin, were ineffective in inhibiting cell growth. Cell cycle analysis showed that the growth inhibitory effect of Q was due to a blocking effect in the GO/GI phase. Using a whole cell assay with (6,7-3H) (Gabor, 1988). Recently it has been reported that in the rat uterus and in the MCF-7 human breast cancer cell line the flavonoid quercetin (Q) inhibits cell growth and the uterotrophic response to oestradiol (Markaverich et al., 1988 Growth experiments Cells were plated in six-well flat bottom plates (Falcon 3046, Becton Dickinson, Lincoln Park, NJ, USA) at a concentration of I x 105 cells ml-' in MEM supplemented as above. After 24 h, the medium was replaced with fresh medium and Q (3,3',4',5,7-pentahydroxyflavone), rutin (3-rhamnosylglucoside of Q) and hesperidin (7-rhamnosylglucoside of Hesperitin) (3'-5-3-hydroxy-4-methoxy-flavanone) (Aldrich, Steinhein, FRG) were added from an absolute ethanol (Q) or DMSO stock solution (rutin, hesperidin). Control cells were treated with the same amount of vehicle alone. The final ethanol and DMSO concentration never exceeded 1 % (v/v) and 0.5% (v/v), in either control or treated samples, respectively.Quadruplicate haemocytometer counts of triplicate culture dishes were performed at the time indicated in the figures.Cell cycle analysis OVCA 433 cells were plated at a concentration of I x 105 cells ml-' in MEM supplemented as above. Twenty-four hours after plating, medium was replaced with fresh medium containing 1O0M Q or vehicle alone (ethanol). After 3 days, cells were incubated for 30 min at 37°C in the same medium with 10ftM bromodeoxyuridine (Sigma Deisenhofen, FRG

Certain jaesekanadiol p-hydroxy- and p-methoxybenzoates - typical of Ferula communis and Ferula arrigonii sardinian plants - show antiproliferative activity on human colon cancer less. The inhibitory doses 50%, calculated after 72 h of treatment, revealed that the antiproliferative capacity of the compounds was in the following descending order: ferutinin > 2alpha-OH-ferutidin > ferutidin > siol anisate > lapiferin > jaeskeanadiol. Evidence is presented that interaction with type II estrogen-binding sites (EBS) underlies this activity.

It has been demonstrated that the flavonoid quercetin (3,3',4',5,7-pentahydroxyflavone; Q) inhibits the growth of several cancer cell lines. There is evidence suggesting that the antiproliferative activity of this substance is mediated by the so-called type II estrogen-binding site (type II EBS). We looked for the presence of type II EBS and the effect of Q on the proliferation of an Adriamycin-resistant estrogen-receptor-negative human breast-cancer cell line (MCF-7 ADRr). By whole-cell assay using estradiol labelled with 6,7-tritium [( 3H]-E2) as a tracer, we demonstrated that MCF-7 ADRr cells contain type II EBSs. Competition analysis revealed that diethylstilbestrol (DES) and Q competed with similar potency for [3H]-Es binding to type II EBSs. The antiestrogen tamoxifen (TAM) competed for type II EBSs, albeit to a lesser extent than either DES or Q. Growth experiments demonstrated that Q and DES exerted a dose-dependent inhibition of cell proliferation in the range of concentrations between 10 nM and 10 microM, whereas TAM was less effective. Q could also inhibit colony formation in a clonogenic assay. Our results indicate that multidrug-resistant estrogen-receptor-negative MCF-7 cells express type II EBSs and are sensitive to the inhibitory effect of Q. This substance could be the parent compound of a novel class of anticancer agents.

We show that flavonoids positively regulate type-II estrogen-binding site (type-II EBS) levels both in MCF-7 (ER-positive) and in MDA-MB231 (ER-negative) breast-cancer cells. Type-II EBS were measured by a whole-cell assay at 4 degrees C for 2.5 hr using [3H]-estradiol as tracer. In both cell lines the effect of quercetin (Q) was dose-related and already evident after 12 hr of Q treatment. The increase of type-II EBS levels after Q exposure requires both RNA and protein synthesis, since actinomycin D and cycloheximide completely abolished the stimulatory effect. The ability of flavonoids in inducing type-II EBS is well correlated with their relative binding affinity for type-II EBS. The flavonoid-induced enhancement of type-II EBS levels is accompanied by increased sensitivity of cancer cells to the inhibitory effect of low Q concentrations. Our data suggest that type-II EBS are ligand-regulated receptors.

Radioreceptwial assessment of EGFR expression was prospectively performed on 60 primary human endometrial tumors. Of these, 26 were EGFR-positive while 13 expressed high EGFR levels. High EGFR levels correlated well with poor histopathological grading. No correlation with histopathological type, stage, myometrial invasion, lymph-node involvement or steroid hormone receptor status was observed. Disease-free survival rate was significantly shorter in the cases with high than in the cases with low EGFR levels. These results suggest a potential role of EGFR expression assessment in prognostic characterization of endometrial cancer patients.