Prenylated xanthones: antiproliferative effects and enhancement of the growth inhibitory action of 4-hydroxytamoxifen in estrogen receptor-positive breast cancer cell line

The effects of three prenylated xanthones on the in vitro growth of estrogen-dependent ER (+) MCF-7 (breast), estrogen-independent ER (-) MDA-MB-231 cells (breast), and NCI-H460 (non-small cell lung) were investigated in a complete and/or steroid-free medium. 3,4-Dihydro-12-hydroxy-2,2-dimethyl-2H, 6H-pyrano[3,2-b]xanthen-6-one (4), the most potent against the ER(+) MCF-7 cell line (GI(50) = 5 mu M), showed an enhancement in the anti-estrogenic effect of 4-hydroxytamoxifen in this ER(+) cell line.