TY - JOUR T1 - Coadministrating Luteolin Minimizes the Side Effects of the Aromatase Inhibitor Letrozole JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 270 LP - 277 DO - 10.1124/jpet.114.216754 VL - 351 IS - 2 AU - Fengjuan Li AU - Tsz Yan Wong AU - Shu-mei Lin AU - Simon Chow AU - Wing-hoi Cheung AU - Franky L. Chan AU - Shiuan Chen AU - Lai K. Leung Y1 - 2014/11/01 UR - http://jpet.aspetjournals.org/content/351/2/270.abstract N2 - Aromatase inhibitors (AIs) have been used as adjuvant therapeutic agents for breast cancer. Their adverse side effect on blood lipid is well documented. Some natural compounds have been shown to be potential AIs. In the present study, we compared the efficacy of the flavonoid luteolin to the clinically approved AI letrozole (Femara; Novartis Pharmaceuticals, East Hanover, NJ) in a cell and a mouse model. In the in vitro experimental results for aromatase inhibition, the Ki values of luteolin and letrozole were estimated to be 2.44 µM and 0.41 nM, respectively. Both letrozole and luteolin appeared to be competitive inhibitors. Subsequently, an animal model was used for the comparison. Aromatase-expressing MCF-7 cells were transplanted into ovariectomized athymic mice. Luteolin was given by mouth at 5, 20, and 50 mg/kg, whereas letrozole was administered by intravenous injection. Similar to letrozole, luteolin administration reduced plasma estrogen concentrations and suppressed the xenograft proliferation. The regulation of cell cycle and apoptotic proteins—such as a decrease in the expression of Bcl-xL, cyclin-A/D1/E, CDK2/4, and increase in that of Bax—was about the same in both treatments. The most significant disparity was on blood lipids. In contrast to letrozole, luteolin increased fasting plasma high-density lipoprotein concentrations and produced a desirable blood lipid profile. These results suggested that the flavonoid could be a coadjuvant therapeutic agent without impairing the action of AIs. ER -