The Experts below are selected from a list of 1233 Experts worldwide ranked by ideXlab platform
Robert J Damato - One of the best experts on this subject based on the ideXlab platform.
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2 Methoxyestradiol inhibits hypoxia inducible factor 1α and suppresses growth of lesions in a mouse model of endometriosis
American Journal of Pathology, 2008Co-Authors: Christian M Becker, Nadine Rohwer, Tae Funakoshi, Thorsten Cramer, Wanja Bernhardt, Amy E Birsner, Judah Folkman, Robert J DamatoAbstract:Endometriosis, the presence of ectopic endometrial tissue outside the uterine cavity, is a common disease affecting women during their reproductive years. Current therapeutic success is often unsatisfactory because of limited insight into disease mechanisms. Nevertheless, angiogenesis plays an essential role in the pathogenesis of the disease, making it a potential novel target for therapy. In the current study, we demonstrate in an established mouse model of endometriosis that transient hypoxia in transplanted endometriosis-like lesions results in the up-regulation of hypoxia-inducible factor-1α (HIF-1α), leading to the expression of vascular endothelial growth factor (VEGF), a key player in endometriosis-associated angiogenesis. Systemic treatment with the angiogenesis inhibitor 2-Methoxyestradiol suppressed HIF-1α expression in vivo, resulting in a decreased downstream expression of HIF-1α target genes, such as for VEGF, phosphoglycerate kinase, and glucose transporter-1. 2-Methoxyestradiol also suppressed VEGF-induced vascular permeability, as demonstrated in a modified Miles assay. Finally, systemic treatment with 2-Methoxyestradiol significantly inhibited the growth of endometriosis-like lesions in a dose-dependent manner. In conclusion, hypoxia appears to play an important role in the pathogenesis of endometriosis and endometriosis-associated angiogenesis, and the angiogenesis inhibitor 2-Methoxyestradiol may be a potential candidate for systemic treatment in the future.
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antiangiogenic effect of oral 2 Methoxyestradiol on choroidal neovascularization in mice
Experimental Eye Research, 2006Co-Authors: Taisaku Funakoshi, Amy E Birsner, Robert J DamatoAbstract:Abstract We evaluated the efficacy of systemic 2-Methoxyestradiol (2ME2) in a laser-induced murine model of choroidal neovascularization (CNV). C57BL/6J mice (8 week old males) were used in this study and divided into four groups. After laser treatment, daily oral treatment with vehicle control, and 30, 50, and 75 mg/kg of 2ME2 was started. Two weeks after laser treatment, digital images of CNV were obtained from fluorescein isothiocyanate-dextran (FITC-dextran) angiography and choroidal flat mount after FITC-dextran perfusion. These images were quantified by NIH image software. Analysis of images from both FITC-dextran angiography and choroidal flat mount with FITC-dextran perfusion demonstrated that the 2ME2 treated groups showed a statistically significant, dose-dependent decrease in CNV. No toxicity or weight loss was observed during the treatment. Significant antiangiogenic effects of oral 2ME2 on laser induced CNV were observed. Since 2ME2 (Panzem®) has demonstrated good safety in phase I/II trials for cancer, it has the potential to be used as a novel oral treatment for age-related macular degeneration.
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interactions of 2 Methoxyestradiol an endogenous mammalian metabolite with unpolymerized tubulin and with tubulin polymers
Biochemistry, 1996Co-Authors: Ernest Hamel, Chii M Lin, Evelyn Flynn, Robert J DamatoAbstract:2-Methoxyestradiol (2ME) is an endogenous mammalian catabolite of estradiol with antimitotic activity. Although it is a competitive inhibitor of the binding of colchicine to tubulin, it has unusual effects on glutamate-induced tubulin polymerization. Polymer that was little changed in morphology assembled at a reduced rate and was relatively cold stable. We have now examined interactions of [4-3H]2ME with unpolymerized tubulin and polymer. The [3H]2ME binds avidly to tubulin even on ice, and it is readily displaced by other colchicine site drugs. An association rate constant on ice of 1.9 × 102 M-1s-1 was obtained. Scatchard analysis indicated a single class of binding site and an association equilibrium constant of 5.7 × 105 M-1. These values lead to a calculated dissociation rate constant of 3.3 × 10-4 s-1. In glutamate-induced tubulin assembly, a reaction that requires GTP and leads to the formation of sheets of parallel protofilaments, increasing amounts of [3H]2ME were incorporated into polymer, reac...
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2 Methoxyestradiol an endogenous mammalian metabolite inhibits tubulin polymerization by interacting at the colchicine site
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Robert J Damato, Judah Folkman, Chii M Lin, Evelyn Flynn, Ernest HamelAbstract:A metabolite of estradiol, 2-Methoxyestradiol (2ME), inhibits angiogenesis in the chicken embryo chorioallantoic membrane assay. Since 2ME causes mitotic perturbations, we examined its interactions with tubulin. In our standard 1.0 M glutamate system (plus 1.0 mM MgCl2 at 37 degrees C), superstoichiometric concentrations (relative to tubulin) of 2ME inhibited the nucleation and propagation phases of tubulin assembly but did not affect the reaction extent. Although polymer formed in the presence of 2ME was more cold-stable than control polymer, morphology was little changed. Under suboptimal reaction conditions (0.8 M glutamate/no MgCl2 at 26 degrees C), substoichiometric 2ME totally inhibited polymerization. No other estrogenic compound was as effective as 2ME as an inhibitor of polymerization or of the binding of colchicine to tubulin. Inhibition of colchicine binding was competitive (Ki, 22 microM). Thus, a mammalian metabolite of estradiol binds to the colchicine site of tubulin and, depending on reaction conditions, either inhibits assembly or seems to be incorporated into a polymer with altered stability properties.
Ernest Hamel - One of the best experts on this subject based on the ideXlab platform.
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effects of altering the electronics of 2 Methoxyestradiol on cell proliferation on cytotoxicity in human cancer cell cultures and on tubulin polymerization
Journal of Medicinal Chemistry, 2004Co-Authors: Allison B Edsall, Arasambattu K Mohanakrishnan, Donglai Yang, Philip E Fanwick, Ernest Hamel, Arthur D Hanson, Gregory E Agoston, Mark CushmanAbstract:A series of new analogues of 2-Methoxyestradiol (1) were synthesized to further elucidate the relationships between structure and activity. The compounds were designed to diminish the potential for metabolic deactivation at positions 2 and 17 and were analyzed as inhibitors of tubulin polymerization and for cytotoxicity. 17α-Methyl-β-estradiol (30), 2-propynyl-17α-methylestradiol (39), 2-ethoxy-17-(1‘-methylene)estra-1,3,5(10)-triene-3-ol (50) and 2-ethoxy-17α-methylestradiol (51) showed similar or greater tubulin polymerization inhibition than 2-Methoxyestradiol (1) and contained moieties that are expected to inhibit deactivating metabolic processes. All of the compounds tested were cytotoxic in the panel of 55 human cancer cell cultures, and generally, the derivatives that displayed the most activity against tubulin were also the most cytotoxic.
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synthesis of analogs of 2 Methoxyestradiol with enhanced inhibitory effects on tubulin polymerization and cancer cell growth
Journal of Medicinal Chemistry, 1997Co-Authors: Mark Cushman, Ernest Hamel, John A Katzenellenbogen, Chii M Lin, Ravi K Varma, Siya Ram, Yesh P SachdevaAbstract:A new series of estradiol analogs was synthesized in an attempt to improve on the anticancer activity of 2-Methoxyestradiol, a naturally occurring mammalian tubulin polymerization inhibitor. The compounds were evaluated as inhibitors of tubulin polymerization and the binding of [3H]colchicine to tubulin, as well as for in vitro cytotoxicity in human cancer cell cultures. Overall, the most potent of the new compounds were 2-(2‘,2‘,2‘-trifluoroethoxy)-6-oximinoestradiol, 2-ethoxy-6-oximinoestradiol, and 2-ethoxy-6-methoximinoestradiol. These agents lacked significant affinity for the estrogen receptor. The cytotoxicities of the compounds correlated in general with their abilities to inhibit tubulin polymerization, thus supporting inhibition of tubulin polymerization as the primary mechanism causing inhibition of cell growth.
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interactions of 2 Methoxyestradiol an endogenous mammalian metabolite with unpolymerized tubulin and with tubulin polymers
Biochemistry, 1996Co-Authors: Ernest Hamel, Chii M Lin, Evelyn Flynn, Robert J DamatoAbstract:2-Methoxyestradiol (2ME) is an endogenous mammalian catabolite of estradiol with antimitotic activity. Although it is a competitive inhibitor of the binding of colchicine to tubulin, it has unusual effects on glutamate-induced tubulin polymerization. Polymer that was little changed in morphology assembled at a reduced rate and was relatively cold stable. We have now examined interactions of [4-3H]2ME with unpolymerized tubulin and polymer. The [3H]2ME binds avidly to tubulin even on ice, and it is readily displaced by other colchicine site drugs. An association rate constant on ice of 1.9 × 102 M-1s-1 was obtained. Scatchard analysis indicated a single class of binding site and an association equilibrium constant of 5.7 × 105 M-1. These values lead to a calculated dissociation rate constant of 3.3 × 10-4 s-1. In glutamate-induced tubulin assembly, a reaction that requires GTP and leads to the formation of sheets of parallel protofilaments, increasing amounts of [3H]2ME were incorporated into polymer, reac...
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synthesis antitubulin and antimitotic activity and cytotoxicity of analogs of 2 Methoxyestradiol an endogenous mammalian metabolite of estradiol that inhibits tubulin polymerization by binding to the colchicine binding site
Journal of Medicinal Chemistry, 1995Co-Authors: Mark Cushman, John A Katzenellenbogen, Chii M Lin, Ernest HamelAbstract:In order to define the structural parameters associated with the antitubulin activity and cytotoxicity of 2-Methoxyestradiol, a mammalian metabolite of estradiol, an array of analogs was synthesized and evaluated. The potencies of the new congeners as inhibitors of tubulin polymerization and colchicine binding were determined using tubulin purified from bovine brain, and the cytotoxicities of the new compounds were studied in a variety of cancer cell cultures. Maximum antitubulin activity was observed in estradiols having unbranched chain substituents at the 2-position with three non-hydrogen atoms. 2-Ethoxyestradiol and 2-((E)-1-propenyl)-estradiol were substantially more potent than 2-Methoxyestradiol itself. The tubulin polymerization inhibitors in this series displayed significantly higher cytotoxicities in the MDA-MB-435 breast cancer cell line than in the other cell lines studied. The potencies of the analogs as cytotoxic and antimitotic agents in cancer cell cultures correlated with their potencies as inhibitors of tubulin polymerization, supporting the hypothesis that inhibition of tubulin polymerization is the mechanism of the cytotoxic action of 2-Methoxyestradiol and its congeners. Several of the more potent analogs were tested in an estrogen receptor binding assay, and their affinities relative to estradiol were found to be very low.
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2 Methoxyestradiol an endogenous mammalian metabolite inhibits tubulin polymerization by interacting at the colchicine site
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Robert J Damato, Judah Folkman, Chii M Lin, Evelyn Flynn, Ernest HamelAbstract:A metabolite of estradiol, 2-Methoxyestradiol (2ME), inhibits angiogenesis in the chicken embryo chorioallantoic membrane assay. Since 2ME causes mitotic perturbations, we examined its interactions with tubulin. In our standard 1.0 M glutamate system (plus 1.0 mM MgCl2 at 37 degrees C), superstoichiometric concentrations (relative to tubulin) of 2ME inhibited the nucleation and propagation phases of tubulin assembly but did not affect the reaction extent. Although polymer formed in the presence of 2ME was more cold-stable than control polymer, morphology was little changed. Under suboptimal reaction conditions (0.8 M glutamate/no MgCl2 at 26 degrees C), substoichiometric 2ME totally inhibited polymerization. No other estrogenic compound was as effective as 2ME as an inhibitor of polymerization or of the binding of colchicine to tubulin. Inhibition of colchicine binding was competitive (Ki, 22 microM). Thus, a mammalian metabolite of estradiol binds to the colchicine site of tubulin and, depending on reaction conditions, either inhibits assembly or seems to be incorporated into a polymer with altered stability properties.
Thomas J Thekkumkara - One of the best experts on this subject based on the ideXlab platform.
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2 Methoxyestradiol binding of gpr30 down regulates angiotensin at1 receptor
European Journal of Pharmacology, 2014Co-Authors: Sivaramakrishna Koganti, Russell Snyder, Upendra Gumaste, Vardan T Karamyan, Thomas J ThekkumkaraAbstract:Controlling angiotensin AT1 receptor function has been shown to be protective for many pathophysiological disorders. Although estrogen metabolite, 2-Methoxyestradiol (2ME2) can down-regulate angiotensin AT1 receptor expression independently of nuclear receptors, no specific cellular targets have been identified. This study was focused on identification and validation of a cellular target responsible for 2ME2-mediated angiotensin AT1 receptor down-regulation in a continuously passaged rat liver epithelial cell line. Cell membranes were isolated and used to determine 2ME2 specific binding. Cell membranes exposed to [3H]2ME2 showed specific saturable binding, which was found to be pertussis toxin (PTx) sensitive. Under similar conditions, G-protein coupled receptor 30 (GPR30) agonist (G1) and antagonist (G15) inhibited 2ME2 specific binding. In these cells GPR30 was found localized to endoplasmic reticulum (ER) membranes. In intact cells, G1 down-regulated angiotensin AT1 receptor expression and this effect was reversed by G15. Furthermore, 2ME2 mediated activation of epidermal growth factor receptor (EGFR) followed by ERK1/2 phosphorylation, an essential signaling step in angiotensin AT1 receptor down-regulation, was abrogated by G15, suggesting that this signal is GPR30 dependent. Additionally, EGF was found to independently down-regulate angiotensin AT1 receptor in an ERK1/2-dependent manner. In summary, our results demonstrate for the first time that 2ME2 down-regulation of angiotensin AT1 receptor is dependent on ER membrane-associated GRP30. Moreover, this effect is facilitated by GPR30 dependent transactivation of EGFR and ERK1/2 phosphorylation. This study provides further understanding of the physiological significance of 2ME2 and its role in modulating angiotensin AT1 receptor expression.
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2 Methoxyestradiol binding of gpr30 down regulates angiotensin at1 receptor
European Journal of Pharmacology, 2014Co-Authors: Sivaramakrishna Koganti, Russell Snyder, Upendra Gumaste, Vardan T Karamyan, Thomas J ThekkumkaraAbstract:Controlling angiotensin AT1 receptor function has been shown to be protective for many pathophysiological disorders. Although estrogen metabolite, 2-Methoxyestradiol (2ME2) can down-regulate angiotensin AT1 receptor expression independently of nuclear receptors, no specific cellular targets have been identified. This study was focused on identification and validation of a cellular target responsible for 2ME2-mediated angiotensin AT1 receptor down-regulation in a continuously passaged rat liver epithelial cell line. Cell membranes were isolated and used to determine 2ME2 specific binding. Cell membranes exposed to [3H]2ME2 showed specific saturable binding, which was found to be pertussis toxin (PTx) sensitive. Under similar conditions, G-protein coupled receptor 30 (GPR30) agonist (G1) and antagonist (G15) inhibited 2ME2 specific binding. In these cells GPR30 was found localized to endoplasmic reticulum (ER) membranes. In intact cells, G1 down-regulated angiotensin AT1 receptor expression and this effect was reversed by G15. Furthermore, 2ME2 mediated activation of epidermal growth factor receptor (EGFR) followed by ERK1/2 phosphorylation, an essential signaling step in angiotensin AT1 receptor down-regulation, was abrogated by G15, suggesting that this signal is GPR30 dependent. Additionally, EGF was found to independently down-regulate angiotensin AT1 receptor in an ERK1/2-dependent manner. In summary, our results demonstrate for the first time that 2ME2 down-regulation of angiotensin AT1 receptor is dependent on ER membrane-associated GRP30. Moreover, this effect is facilitated by GPR30 dependent transactivation of EGFR and ERK1/2 phosphorylation. This study provides further understanding of the physiological significance of 2ME2 and its role in modulating angiotensin AT1 receptor expression.
Sivaramakrishna Koganti - One of the best experts on this subject based on the ideXlab platform.
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2 Methoxyestradiol binding of gpr30 down regulates angiotensin at1 receptor
European Journal of Pharmacology, 2014Co-Authors: Sivaramakrishna Koganti, Russell Snyder, Upendra Gumaste, Vardan T Karamyan, Thomas J ThekkumkaraAbstract:Controlling angiotensin AT1 receptor function has been shown to be protective for many pathophysiological disorders. Although estrogen metabolite, 2-Methoxyestradiol (2ME2) can down-regulate angiotensin AT1 receptor expression independently of nuclear receptors, no specific cellular targets have been identified. This study was focused on identification and validation of a cellular target responsible for 2ME2-mediated angiotensin AT1 receptor down-regulation in a continuously passaged rat liver epithelial cell line. Cell membranes were isolated and used to determine 2ME2 specific binding. Cell membranes exposed to [3H]2ME2 showed specific saturable binding, which was found to be pertussis toxin (PTx) sensitive. Under similar conditions, G-protein coupled receptor 30 (GPR30) agonist (G1) and antagonist (G15) inhibited 2ME2 specific binding. In these cells GPR30 was found localized to endoplasmic reticulum (ER) membranes. In intact cells, G1 down-regulated angiotensin AT1 receptor expression and this effect was reversed by G15. Furthermore, 2ME2 mediated activation of epidermal growth factor receptor (EGFR) followed by ERK1/2 phosphorylation, an essential signaling step in angiotensin AT1 receptor down-regulation, was abrogated by G15, suggesting that this signal is GPR30 dependent. Additionally, EGF was found to independently down-regulate angiotensin AT1 receptor in an ERK1/2-dependent manner. In summary, our results demonstrate for the first time that 2ME2 down-regulation of angiotensin AT1 receptor is dependent on ER membrane-associated GRP30. Moreover, this effect is facilitated by GPR30 dependent transactivation of EGFR and ERK1/2 phosphorylation. This study provides further understanding of the physiological significance of 2ME2 and its role in modulating angiotensin AT1 receptor expression.
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2 Methoxyestradiol binding of gpr30 down regulates angiotensin at1 receptor
European Journal of Pharmacology, 2014Co-Authors: Sivaramakrishna Koganti, Russell Snyder, Upendra Gumaste, Vardan T Karamyan, Thomas J ThekkumkaraAbstract:Controlling angiotensin AT1 receptor function has been shown to be protective for many pathophysiological disorders. Although estrogen metabolite, 2-Methoxyestradiol (2ME2) can down-regulate angiotensin AT1 receptor expression independently of nuclear receptors, no specific cellular targets have been identified. This study was focused on identification and validation of a cellular target responsible for 2ME2-mediated angiotensin AT1 receptor down-regulation in a continuously passaged rat liver epithelial cell line. Cell membranes were isolated and used to determine 2ME2 specific binding. Cell membranes exposed to [3H]2ME2 showed specific saturable binding, which was found to be pertussis toxin (PTx) sensitive. Under similar conditions, G-protein coupled receptor 30 (GPR30) agonist (G1) and antagonist (G15) inhibited 2ME2 specific binding. In these cells GPR30 was found localized to endoplasmic reticulum (ER) membranes. In intact cells, G1 down-regulated angiotensin AT1 receptor expression and this effect was reversed by G15. Furthermore, 2ME2 mediated activation of epidermal growth factor receptor (EGFR) followed by ERK1/2 phosphorylation, an essential signaling step in angiotensin AT1 receptor down-regulation, was abrogated by G15, suggesting that this signal is GPR30 dependent. Additionally, EGF was found to independently down-regulate angiotensin AT1 receptor in an ERK1/2-dependent manner. In summary, our results demonstrate for the first time that 2ME2 down-regulation of angiotensin AT1 receptor is dependent on ER membrane-associated GRP30. Moreover, this effect is facilitated by GPR30 dependent transactivation of EGFR and ERK1/2 phosphorylation. This study provides further understanding of the physiological significance of 2ME2 and its role in modulating angiotensin AT1 receptor expression.
Xilong Zheng - One of the best experts on this subject based on the ideXlab platform.
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estrogen metabolite 2 Methoxyestradiol prevents hypertension in deoxycorticosterone acetate salt rats
Cardiovascular Drugs and Therapy, 2013Co-Authors: Wensu Yuan, Pavneet Singh, Yu Gui, Xilong ZhengAbstract:Purpose Our early work showed that the estrogen metabolite 2-Methoxyestradiol (2ME) inhibits proliferation of vascular smooth muscle cells (SMCs) and vascular contractility through an endothelium-dependent mechanism. The aim of this study was to examine whether 2ME prevents the development of hypertension in rats.
