Treatment Of Estrogen-dependent Cancer Research Articles

Estrogen-like and tissue-selective effects of 7-methoxycoumarin from Ficus umbellata (Moraceae): an in vitro and in vivo study

BackgroundFicus umbellata is a medicinal plant previously shown to endow estrogenic properties. Its major component was isolated and characterized as 7-methoxycoumarin (MC). Noteworthy, coumarins and the respective active metabolite 7-hydroxycoumarin analogs have shown aromatase inhibitory activity, which is of particular interest in the treatment of estrogen-dependent cancers. The present work aimed at evaluating the estrogenic/antiestrogenic effects of MC in vitro and in vivo.MethodsTo do so, in vitro assays using E-screen and reporter gene were done. In vivo, a 3-day uterotrophic assay followed by a postmenopausal-like rat model to characterize MC as well as F. umbellata aqueous extract in ovariectomized Wistar rats was performed. The investigations focused on histological (vaginal and uterine epithelial height) and morphological (uterine wet weight, vagina stratification and cornification) endpoints, bone mass, biochemical parameters and lipid profile.ResultsMC induced a significant (p < 0.05) MCF-7 cell proliferation at a concentration of 0.1 μM, but did not inhibit the effect induced by estradiol in both E-screen and reporter gene assays. In vivo, MC treatment did not show an uterotrophic effect in both rat models used. However, MC (1 mg/kg) induced a significant increase (p < 0.01) of vaginal epithelial height. No significant change was observed with MC in abdominal fat weight, serum lipid levels and bone weight.ConclusionThese results suggest that MC has a weak estrogenic activity in vitro and in vivo that accounts only in part to the estrogenicity of the whole plant extract. MC could be beneficial with regard to vagina dryness as it showed a tissue specific effect without exposing the uterus to a potential tumorigenic growth.

3D QSAR studies, pharmacophore modeling and virtual screening on a series of steroidal aromatase inhibitors.

Aromatase inhibitors are the most important targets in treatment of estrogen-dependent cancers. In order to search for potent steroidal aromatase inhibitors (SAIs) with lower side effects and overcome cellular resistance, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed on a series of SAIs to build 3D QSAR models. The reliable and predictive CoMFA and CoMSIA models were obtained with statistical results (CoMFA: q2 = 0.636, r2ncv = 0.988, r2pred = 0.658; CoMSIA: q2 = 0.843, r2ncv = 0.989, r2pred = 0.601). This 3D QSAR approach provides significant insights that can be used to develop novel and potent SAIs. In addition, Genetic algorithm with linear assignment of hypermolecular alignment of database (GALAHAD) was used to derive 3D pharmacophore models. The selected pharmacophore model contains two acceptor atoms and four hydrophobic centers, which was used as a 3D query for virtual screening against NCI2000 database. Six hit compounds were obtained and their biological activities were further predicted by the CoMFA and CoMSIA models, which are expected to design potent and novel SAIs.

Pharmacophore modeling, virtual screening, and 3D-QSAR studies on a series of non-steroidal aromatase inhibitors

Aromatase inhibitors are the most important targets in treatment of estrogen-dependent cancers. In order to search for potent non-steroidal aromatase inhibitors (NSAIs) with lower side effects and overcome cellular resistance, Genetic Algorithm with Linear Assignment of Hypermolecular Alignment of Database was used to derive 3D pharmacophore models. The obtained best pharmacophore model contains one acceptor atom, one donor atom, and two hydrophobes, which was used in effective alignment of dataset. In succession, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed on 84 structurally diverse NSAIs to build 3D-QSAR models based on both pharmacophore and docking alignments. The CoMFA and CoMSIA models based on the pharmacophore alignment show better statistical results (CoMFA: q2 = 0.634, rncv2 = 0.986, rpred2 = 0.737; CoMSIA: q2 = 0.668, rncv2 = 0.926, rpred2 = 0.708). This 3D-QSAR approach provides significant insights that can be used to develop novel and potent NSAIs. In addition, the best pharmacophore model was used as a 3D query for virtual screening against NCI2000 database. The hit compounds were further filtered by docking, and their biological activities were predicted by the CoMFA and CoMSIA models, and six structurally diverse compounds with good predicted pIC50 values were obtained, which are expected to design novel NSAIs with new skeletons.

Estrogen-Induced Mitochondrial Reactive Oxygen Species as Signal-Transducing Messengers

We report here evidence in support of the role of 17beta-estradiol- (E2-) induced mitochondrial (mt) reactive oxygen species (ROS) as signal-transducing messengers. On the basis of monitoring the oxidation of 2',7'-dichlorofluorescin by spectrofluorometry, flow cytometry, and confocal microscopy, we have identified that exposure of E2 triggers the immediate rapid production of intracellular ROS ranging from a 1- to severalfold increase in a variety of cells. E2-stimulated ROS production does not correlate with the activity of the estrogen receptor (ER) in the cells. The ROS is most likely hydrogen peroxide based on its inhibition by antioxidants and catalase and lack of any effects of E2 on O(2)(*)(-) or NO(*) formation. Confocal microscopy showed that ROS is localized in the perinuclear mitochondria. E2 through anchorage- and integrin-dependent signaling to mitochondria increased ROS generation. Increased intracellular ROS formation identified here for the first time may explain the mechanism of previously reported oxidative damage and subsequent genetic alterations including mutations produced by elevated concentrations of estrogens. The functional consequences of E2-induced ROS formation included the enhanced cell motility as shown by the increase in cdc42 and activation of Pyk2 and the increased phosphorylation of signaling proteins c-jun and CREB. E2-induced ROS activated the binding of three oxidant-sensitive transcription factors: AP-1, CREB, and nuclear respiratory factor 1. In addition to ERs as signaling molecules, our findings further revealed that E2-induced mt ROS also act as signal transducing messengers and suggest new targets for the development of antioxidant-based drugs or antioxidant gene therapy for the prevention and treatment of estrogen-dependent cancer.

Synthesis of 14C-labelled CGS 16949A (Fadrozole HCl), a potent aromatase inhibitor

CGS 16949A (Fadrozole HCl) is an aromatase inhibitor currently used in Japan for the treatment of estrogen-dependent cancer. A 14C-labelled form of this compound was synthesized for metabolism and pharmacokinetic studies. The synthesis pathway includes six steps, which are shown in synthetic Scheme 2. Initially, 4-bromotoluene was reacted with [14C]CuCN to yield 4-tolunitrile-[14C]-cyano. The nitrile was brominated on the α carbon to give an intermediate that was used to N-alkylate a known imidazole analogue. The product was treated with thionyl chloride to convert a 3-hydroxy propyl moiety to its chloro analogue. Treatment with potassium butoxide gave [14C] fadrozole as the free base via ring closure. Hydrogen chloride gas was used to give the desired salt [14C]CGS 16949A. Using this procedure, [14C]CGS 16949A was prepared with 97% radiochemical purity. The overall radiochemical yield for the synthesis was 1% from [14C]KCN. © 1997 John Wiley & Sons, Ltd.

The endocrine effects of long-term treatment with mifepristone (RU 486).

Mifepristone (RU 486) is a compound with progesterone as well as cortisol-blocking activities. We investigated the endocrine effects of long-term therapy of 10 patients with meningiomas with 200 mg mifepristone daily for 1 yr. Most patients initially complained of nausea, vomiting, and/or tiredness. In four patients prednisone (7.5 mg/day) had to be given simultaneously in order to overcome these side-effects. In retrospect those patients who presented with the most severe side-effects showed the most rapidly occurring activation of the hypothalamo-pituitary-adrenal-axis, as measured by an increase of circulating cortisol levels as well as of urinary cortisol excretion. Therapy with RU 486 activated the hypothalamo-pituitary-adrenal axis, resulting in a resetting of this system at a higher level at which the diurnal rhythm and the responsiveness to CRH stimulation were maintained, whereas the sensitivity to dexamethasone had diminished. Secondarily the production of androstenedione and estradiol increased considerably. These endocrine changes were caused by the induction of partial cortisol receptor resistance during therapy with RU 486. The compensatory overproduction of androgens and consequently of estrogens during long-term RU 486 therapy might limit its use as a single treatment in the treatment of estrogen-dependent cancer.