Quercetin induces type-II estrogen-binding sites in estrogen-receptor-negative (MDA-MB231) and estrogen-receptor-positive (MCF-7) human breast-cancer cell lines

✍ Scribed by G. Scambia; S. Mancuso; P. Benedetti Panici; R. De Vincenzo; G. Ferrandina; G. Bonanno; F. O. Ranelletti; M. Piantelli; A. Capelli

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: French
• Weight: 536 KB
• Volume: 54
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/ijc.2910540318

✦ Synopsis

Abstract

We show that flavonoids positively regulate type‐II estrogen‐binding site (type‐ll EBS) levels both in MCF‐7 (ER‐positive) and in MDA‐MB231 (ER‐negative) breast‐cancer cells. Type‐ll EBS were measured by a whole‐cell assay at 4°C for 2.5 hr using [^3^H]‐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‐ll 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‐ll EBS is well correlated with their relative binding affinity for type‐ll EBS. The flavonoid‐induced enhancement of type‐ll EBS levels is accompanied by increased sensitivity of cancer cells to the inhibitory effect of low Q concentrations. Our data suggest that type‐ll EBS are ligand‐regulated receptors.