Tamoxifen administration to mice.
The strategy of fusing a protein of interest to a hormone-binding domain (HBD) of a steroid hormone receptor allows fine control of the activity of the fused protein. Such fusion proteins are inactive in the absence of ligand, because they are complexed with a variety of intracellular polypeptides. Upon ligand binding, the receptor is released from its inhibitory complex and the fusion protein becomes functional. In the murine estrogen receptor (ER) fusion system, proteins are fused to the HBD of the ER. The system relies on the use of a mutant ER known as ER(TAM). Compared to the wild-type HBD, ER(TAM) has 1000-fold lower affinity for estrogen, yet remains responsive to activation by the synthetic steroid 4-hydroxytamoxifen (4-OHT). Because 4-OHT is expensive, animals can be treated with the cheaper precursor tamoxifen, which is converted into 4-OHT by a liver enzyme. Here we present an overview of the methods used to deliver tamoxifen to mice. The most used method is intraperitoneal injection, because the amount of administered compound can be better controlled, but delivery by oral gavage is also possible. For short-term and immediate-effect studies or when conversion of tamoxifen by the liver is to be avoided, 4-OHT can be used directly.
Vall d'Hebron Institute of Oncology (VHIO), Barcelona 08035, Spain; Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain;
Jonathan
J
Whitfield
Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom.
Trevor
T
Littlewood
Vall d'Hebron Institute of Oncology (VHIO), Barcelona 08035, Spain; Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain;
Laura
L
Soucek
D000284:Administration, Oral; D000818:Animals; D005786:Gene Expression Regulation / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D051379:Mice; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D020845:Selective Estrogen Receptor Modulators / Q000008:administration & dosage*; D013629:Tamoxifen / Q000008:administration & dosage*
D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen