FLTX1 is a fluorescent Tamoxifen derivative that can specifically label intracellular Tamoxifen-binding sites (estrogen receptors) under permeabilized and non-permeabilized conditions. FLTX1 exhibits the potent antiestrogenic properties of Tamoxifen in breast cancer cells. FLTX1 is devoid of the estrogenic agonistic effect on the uterus[1][2].
FLTX1 (0.01-10 μM; 6 d) reduces MCF7 cell proliferation in a dose-dependent manner. FLTX1 (pretreated 24 h) counteracts the increase in cell growth induced by E2 down to the vehicle level[1].FLTX1 (50 μM; 2 h) exhibits a dose-dependent competition with Tamoxifen (Tx) in MCF7 cells[1].FLTX1 (0.1 nM-100 μM; 18 h) competitively displaces the [3H] E2 binding to rat uterine estrogen receptors (ER) rat uterus cytosol, with an IC50 of 87.5 nM[1].FLTX1 (0.1 nM-10 μM; pretreated 8 h) reduces the estradiol-induced luciferase expression activity in a dose-dependent manner. FLTX1 (15-16 h) is devoid of the potent estrogenic agonist activity in both transiently transfected MCF7 cells and stably transfected T47D-KBluc cells[1].
FLTX1 (0.01-1 mg/kg/d; s.c. for 3 d) is lacked of the estrogenic uterotrophic (and also cervical and vaginal), hyperplasic and hypertrophic effects, and failed to alter basal proliferating cell nuclear antigen immunoreactivity in mice and rats[1].
[1]. Marrero-Alonso J, et, al. Unique SERM-like properties of the novel fluorescent tamoxifen derivative FLTX1. Eur J Pharm Biopharm. 2013 Nov;85(3 Pt B):898-910.
[2]. Morales A, et, al. Colocalization of Estrogen Receptors with the Fluorescent Tamoxifen Derivative, FLTX1, Analyzed by Confocal Microscopy. Methods Mol Biol. 2016;1366:163-173.