AbstractBackground: The mechanisms by which tamoxifen inhibits breast tumor growth are not completely understood. Partial agonist antiestrogens such as tamoxifen may cause the estrogen receptor (ER) to interact with genes different from those activated by ER bound to estradiol. Doming is a property often associated with, and considered a marker of, differentiation in mammary epithelial cells in culture. This study compared the ability of pure and partial agonist antiestrogens to stimulate doming.Materials and methods: MCF-7 cells grown in medium with 10% calf serum were treated with antiestrogens. Domes were counted in three rows (width of the 4× field) across the flask.Results: Three partial agonist antiestrogens [4-hydroxytamoxifen (OHT), H1285 and RU 39,411] caused dome formation. None of the pure antiestrogens tested (ICI 164,384, ICI 182,780 and RU 58,668) caused doming. Doming was stimulated in a dose-dependent manner starting at 1 nM OHT with maximum stimulation at 10–100 nM. Estradiol did not stimulate doming, but blocked doming at 1%–10% of the OHT concentration. Trichostatin A (TSA) reduced the level of estrogen receptor alpha (ERα) and adding it 24 h before adding OHT prevented dome formation.Conclusions: OHT and the other partial agonist antiestrogens appear to act through the ER to stimulate doming. The ability of tamoxifen to induce a marker of differentiation may play a role in its inhibition of breast tumors. If so, then the fact that other partial agonist antiestrogens share this ability, but that pure antiestrogens lack it, may be an important consideration in developing new antiestrogens for breast cancer therapy.

2012-01-01·Organic & Biomolecular Chemistry3区 · 化学

Convergent synthesis of a steroidal antiestrogen-mitomycin C hybrid using “click” chemistry

3区 · 化学

Article

作者: David Labaree ; Robert N. Hanson ; John M. Essigmann ; Robert G. Croy ; Kyle Proffitt ; Richard B. Hochberg ; Edward Hua

A convergent synthesis of a novel estrogen receptor-targeted drug hybrid was developed based on structures of the potent anti-proliferative mitomycin C and the steroidal anti-estrogen RU 39411. The steroidal antiestrogen was prepared with an azido-triethylene glycoloxy linker while the mitomycin C derivative (porfirimycin) incorporated a complementary 7-N-terminal alkyne. The two components were ligated using the Huisgen [3 + 2] cycloaddition ("click") reaction. Preliminary biological assays demonstrated that the final hybrid compound retained both potent anti-estrogenic and anti-proliferative activities.

2003-03-01·Steroids4区 · 医学

Decrease of estrogen receptor expression and associated ERE-dependent transcription in MCF-7 breast cancer cells after oligomycin treatment

4区 · 医学

Article

作者: Fabrice Journé ; Hye-Sook Seo ; Christos Sotiriou ; Denis Larsimont ; Guy Leclercq

Oligomycin at 0.01 microM produces very rapid decrease of [3H]estradiol (E2)-binding capacity in MCF-7 cells maintained in culture in glucose- and serum-free medium. Loss of binding capacity was associated with elimination of the estrogen receptor (ER) as well as a decrease of basal expression of ERE-luciferase reporter gene. These effects were not due to major cell death as shown by MTT assay. Hence, the inhibition of ATP synthesis produced by oligomycin seems to influence ER turnover, resulting in very rapid loss of receptor. Withdrawal of oligomycin and maintenance of glucose in the medium led to only a partial reappearance of ER and failed to restore optimal ERE-dependent transcription. Oligomycin significantly down-regulated progesterone receptor (PR) level and partially abrogated E2-induced PR up-regulation, indicating that this drug also affects other nuclear receptors. Treatment of cytosol from MCF-7 cells with acid and alkaline phosphatases decreased [3H]E2-binding capacity, indicating the requirement of ER phosphorylation for optimal hormone binding. On the other hand, oligomycin-induced ER loss was partly compensated by E2 and partial anti-estrogens (AEs; 4-OH-TAM or RU 39 411); i.e. oligomycin failed to improve the E2-induced ER down-regulation and very weakly suppressed partial AE-induced receptor up-regulation. The known ability of these ligands to stabilize ER in the cell nucleus before regulating ER level may explain this phenomenon since such antagonism was not recorded with pure AE RU 58 668, which is known to impede nuclear translocation of the receptor. Interestingly, ligands able to down-regulate ER (i.e. E2 or RU 58 668) increased ER phosphorylation while 4-OH-TAM which up-regulate the receptor had little effect in this regard. Oligomycin failed to strongly affect such phosphorylation enhancements while it produced a weak decrease of basal phosphorylation level. Hence, phosphorylations/dephosphorylations of specific sites on ER and/or co-regulators seem to govern its turnover.

100 项与 RU-39411 相关的药物交易

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