Catalog No.S1972 Synonyms: ICI 46474 Citrate
Molecular Weight(MW): 563.64
Tamoxifen Citrate is an antagonist of the estrogen receptor by competitive inhibition of estrogen binding.
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Effects of DPN, LY500307, Raloxifene and Tamoxifen on cell viability in BSO-treated FRDA fibroblasts. BSO concentration was 1 mM and all steroid concentrations were 100 nM. Depicted are mean ± SD for n= 8 per group. * indicated p<0.05 versus BSO alone-treated cells.
University of North Texas Health Science Center, 2014.. Tamoxifen Citrate purchased from Selleck.
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|Description||Tamoxifen Citrate is an antagonist of the estrogen receptor by competitive inhibition of estrogen binding.|
Tamoxifen displays antitumor effect due to its antiestrogenic activity (ER). Values for the apparent affinity of Tamoxifen for the ER range between 30 and 0.01% of that obtained for estradiol, dependent on different ER source (species), protein concentration and condition used for assay. Binding of Tamoxifen to ER further leads to inhibition expression of estrogen-regulated genes, including growth factors and angiogenic factors secreted by the tumor that may stimulate growth by autocrine or paracrine mechanisms. Tamoxifen also directly induces programmed cell death.  Tamoxifen produces an inhibitory effect on MCF-7 cell [3H]thymidine incorporation and DNA polymerase activity as well as causing a reduction in DNA content of cultures and cell numbers. This inhibitory effect of Tamoxifen on MCF-7 cell growth can be readily reversed by addition of estradiol to the culture medium. 2 and 6 μM Tamoxifen reduces the proportion of cells in S phase and increases the number of cells in G1. At 10 μM, Tamoxifen causes cell death within 48 hr.  Tamoxifen inhibits MCF-7 growth with IC50 of ~10 nM after 10 days treatment. Tamoxifen inhibits plasminogen activator activity of MCF-7, and suppresses estradiol-stimulation of plasminogen activator activity. Tamoxifen also evokes minimal increases in cellular progesterone receptor levels.  Tamoxifen is able to inhibit the growth of prostate cancer cell PC3, PC3-M, and DU145 with IC50 ranged from 5.5-10 μM, which is related to its inhibition of protein kinase C and induction of p21(waf1/cip1). 
|In vivo||Tamoxifen administration to rapidly growing, estradiol-stimulated MCF-7 xenografts results in a dose-dependent retardation or cessation of tumor growth by significantly decreasing tumor cell proliferation in tumor. Tamoxifen treatment results in a slowing of tumor growth (tumor doubling time, 12 days), a significant increase in tumor potential doubling time (Tpot) (6.6 days), and a decrease in labeling index (%LI) (to 8%) by 23 days posttreatment, compared with untreated mice which shows a volume doubling time of 5 days, a Tpot of 2.3 days, and a %LI of 23%.  Tamoxifen has not only antiestrogenic but also estrogenic properties depending on the species, tissue, and gene. Tamoxifen displays favorable effects on bone and serum lipid concentrations and stimulation endometrium. |
Competitive binding assays:Cells are harvested from 150-sq cm T-flasks, and cytosol is prepared at a protein concentration of approximately 2 mg/mL in phosphate buffer. Aliquots of this 180,000 ×g supernatant are then incubated with various concentrations of Tamoxifen and 2.5 nM [3H]estradiol for 16 hr at 0-4 ℃. The free steroids are absorbed by dextran-charcoal [l0 μL of 0.5% Dextran C-5% Norite A in TE buffer] for 1 hr at 0 ℃, and aliquots are counted after centrifugation at 800 ×g, 30 min. The relative binding ability of each competitor is taken as the ratio of the concentration of radioinert estradiol/competitor required to inhibit one-half of the specific [3H]estradiol binding, with the affinity of estradiol set at 100%.
-  Osborne CK. N Engl J Med, 1998, 339(22), 1609-1618.
-  Furr BJ, et al. Pharmacol Therm, 1984, 25(2), 127-205.
-  Katzenellenbogen BS, et al. Cancer Res, 1984, 44(1), 112-119.
|In vitro||DMSO||100 mg/mL (177.41 mM)|
|Ethanol||100 mg/mL (177.41 mM)|
|In vivo||Add solvents to the product individually and in order:
30% PEG400+0.5% Tween80+5% propylene glycol
For best results, use promptly after mixing.
* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.
|Synonyms||ICI 46474 Citrate|
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Clinical Trial Information
|NCT Number||Recruitment||Conditions||Sponsor/Collaborators||Start Date||Phases|
|NCT00026585||Completed||Bipolar Disorder||National Institute of Mental Health (NIMH)|National Institutes of Health Clinical Center (CC)||November 9, 2001||Phase 2|
|NCT03024580||Not yet recruiting||Breast Neoplasm||Instituto Nacional de Cancer, Brazil|Cancer Research UK Cambridge Institute||March 2017||Phase 2|
|NCT02993159||Not yet recruiting||Ductal Breast Carcinoma In Situ|Estrogen Receptor Positive||National Cancer Institute (NCI)||March 2017||Phase 2|
|NCT02988986||Not yet recruiting||Estrogen Receptor Positive Breast Cancer||Jenny C. Chang, MD|Millennium Pharmaceuticals, Inc.|The Methodist Hospital System||February 2017||Phase 2|
|NCT02903121||Not yet recruiting||Bleeding|Implants|Breakthrough Bleeding||Oregon Health and Science University|Merck Womens Health Investigator Initiated Studies Program||January 2017||Phase 2|
|NCT02690870||Not yet recruiting||Infertility||Sun Yat-Sen Memorial Hospital of Sun Yat-Sen University|Sun Yat-sen University||January 2017||Phase 4|
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Frequently Asked Questions
I am wondering if the Tamoxifen (product Cat # S1972) is a 4-hydroxy Tamoxifen form or just plain Tamoxifen Citrate?
The Tamoxifen (S1972) is a prodrug, just plain Tamoxifen citrate.