Research Area: Endometrial cancer
Biological Activity:
CGS 20267 maximally inhibits estradiol production in vitro in LH-stimulated hamster ovarian tissue at 0.1 μM with an IC50 of 0.02 μM and does not significantly affect progesterone production up to 350 μM. In ACTH-stimulated rat adrenal tissue in vitro, aldosterone production was inhibited with an IC50 of 210 μM (10,000 times higher than the IC50 for estradiol production); no significant effect on corticosterone production was seen at 350 μM. In vivo, in ACTH-treated rats, CGS 20267 does not affect plasma levels of corticosterone or aldosterone at a dose of 4 mg/kg p.o. (1000 times higher than the ED50 for aromatase inhibition in vivo) [1]Inhibitory concentrations of letrozole against the aromatase enzyme derived from various cellular and non-cellular sources.IC50 values: Human placental microsomes 11nM, MCF-7Ca cancer cells 0.07 nM, JEG-3 cancer cells 0.07 nM, Hamster Ovarian tissue 20 nM. [2]References on Letrozole[] J. Steroid Bioehem. Molee. Biol, 1990 , 37:1021-102[] Breast Cancer Res Treat , 2007, 105:7–17