Jpn J Physiol. 2001 Dec;51(6):753-9.
Effects of 17beta-estradiol on tension responses and fatigue in the skeletal twitch muscle fibers of frog.

Hatae J.

Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, 814-0180 Japan. hataukuoka-u.ac.jp

The effects of 17beta-estradiol (10(-5) M), an active estrogen, on the tension and fatigue responses of single fiber or fiber bundle prepared from frog skeletal muscle were investigated. The administration of 17beta-estradiol caused a transient potentiation of tetanus tension by field stimulation at every minute. This potentiation was not affected by the presence of nicardipine, suggesting that the action of 17beta-estradiol would place the excitation-contraction (E-C) coupling beyond T-tubule depolarization. Fatigue was produced by repeated tetanic stimulation every second until tension declined to approximately 40% of the initial level. Fibers were then allowed to recover by having tetani given to them every minute. In the normal Ringer solution, the time to 50% of the initial tetanus tension was 41.7 s. With the presence of 17beta-estradiol, the time to 50% tension was faster than that of control. The presence of 17alpha-estradiol, a stereoisomer, caused no potentiation of tetanic tension to be stimulated every minute, and the rate of decline of fatigued response was almost the same as that of control, suggesting the existence of specific estrogen receptors in the frog muscle. In fatigued muscle with or without estrogen, the tension to field stimulation was transient and not sustained. When the fatigued muscle was again treated with field stimulation at every minute after the more-frequent stimulation, the recovery rate was increased in 17beta-estradiol. A prompt reduction in temperature to 5 degree C, from 20 degree C, in the presence of caffeine elicited the tension response, a rapid cooling contracture (RCC). The presence of 17beta-estradiol inhibited peak tension and maximum rate of rise of the RCC only after the repeti




J Steroid Biochem Mol Biol. 2003 Feb;84(2-3):255-7.
Effect of tamoxifen and 2-methoxyestradiol alone and in combination on human breast cancer cell proliferation.

Seeger H, Diesing D, Guckel B, Wallwiener D, Mueck AO, Huober J.

Department of Obstetrics and Gynecology, Section of Endocrinology and Menopause, University Hospital, Schleichstrasse 4, University of Tuebingen, Germany.

Endocrine therapy is widely accepted for the treatment of hormone receptor-positive breast cancer. However, in many cases eventually resistance will develop and tumor regrows. Combination therapy may be one way to resolve this problem. In the present study we investigated the effect of a combination of the widely used antiestrogen tamoxifen with the endogenous estradiol metabolite 2-methoxyestradiol (2-ME) on the proliferation of human estrogen receptor-positive and receptor-negative breast cancer cells.The receptor-positive cell line MCF-7 and the receptor-negative cell line BM were treated with 4-hydroxytamoxifen (4-OHTam) and 2-methoxyestradiol in the concentration range of 0.8-25 microM alone and equimolar combinations for 4 days. The proliferation of the cells was determined using the ATP-chemosensitivity test.4-Hydroxytamoxifen inhibited proliferation of MCF-7 and BM cells with IC(50) values of 31 and 10 microM, the corresponding figures for 2-methoxyestradiol were 52 and 8 microM. The combination showed IC(50) values of 6 microM and 4 microM.These results indicate that a combination of tamoxifen with 2-methoxyestradiol showed an additive inhibitory effect concerning the proliferation of estrogen receptor-positive and receptor-negative breast cancer cell lines. Thus a combination of these substances may allow ameliorating of adverse events of tamoxifen by reducing its concentrations and probably also drug resistance and should be tested in clinical trials.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12711011&dopt=Abstract estradiol




Clin Hemorheol Microcirc. 2001;25(3-4):127-34.
Beta-estradiol effect on erythrocyte aggregation--a controlled in vitro study.

Goncalves I, Saldanha C, Martins e Silva J.

Institute of Biochemistry, Faculty of Medicine, University of Lisbon, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal.

The purpose of this in vitro study was to assess the effect of 17beta-estradiol on hemorheologic parameters, namely on erythrocyte aggregation and deformability and membrane fluidity.Blood samples from 65 women (aged 57 +/- 4 years) undergoing postmenopausal hormone replacement therapy were obtained and were incubated for 5 min in absence and presence of 17beta-estradiol 10(-5) M. The measured parameters were the erythrocyte aggregation (EAI) and deformability (EI), the acetylcholinesterase activity (AChE), the plasma pH and osmolality and the erythrocyte membrane fluidity assessed by fluorescence polarization with two probes 1,6-diphenyl-1,3,5-hexatriene (DPH) and (1-(4-(trimethylamino)-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH). Data analysis was performed using t-Student and Pearson correlation analysis. A statistically significant decrease of the EAI (15.8 +/- 3.02 vs 13.45 +/- 2.3; p<0.001) and an increase of the EI (51.39 +/- 5.64 vs 52.06 +/- 5.36; p<0.01) at shear stress of 30 Pa in presence of 17beta-estradiol 10(-5) M was obtained. There was a decrease in membrane fluidity in 45 blood samples (DPH) and in the other 20 an increase, when beta-estradiol 10(-5) M was present. In vitro beta-estradiol 10(-5) M decreased erythrocyte aggregation in blood samples of postmenopausal women undergoing hormone therapy, which could prevent high blood viscosity and, consequently, cardiovascular events.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11847415&dopt=Abstract estradiol




Environ Toxicol. 2002 Feb;17(1):14-23.
Structure-activity relationships for gene activation oestrogenicity: evaluation of a diverse set of aromatic chemicals.

Schultz TW, Sinks GD, Cronin MT.

Department of Comparative Medicine, College of Veterinary Medicine, University of Tennessee, 2407 River Drive, Knoxville, Tennessee 37996-4500, USA. m.t.croniivjm.ac.uk

Structure-activity relationships for oestrogenicity were developed based on 120 aromatic chemicals evaluated in the Saccharomyces cerevisiae-based Lac-Z reporter assay. Relative gene activation was compared to 17 beta-estradiol and varied over eight orders of magnitude. Analysis of the data compared to 17 beta-estradiol identified three structural criteria that were related to xenoestrogen activity and potency: (1) the hydrogen-bonding ability of the phenolic ring mimicking the A-ring, (2) a hydrophobic centre similar in size and shape to the B- and C-rings, and (3) a hydrogen-bond donor mimicking the 17 beta-hydroxyl moiety of the D-ring, especially with an oxygen-to-oxygen distance similar to that between the 3- and 17 beta-hydroxyl groups of 17 beta-estradiol. Binding data were segregated into activity clusters including strong, moderate, weak, and detectable gene expression, and those compounds that were inactive. The hydrogen-bonding ability of hydroxy group in the 3-position on 17 beta-estradiol was observed to be essential for gene activation. Compounds with a 4-hydroxyl substituted benzene ring and a hydrophobic moiety of size and shape equivalent to the B-ring of 17 beta-estradiol were generally observed to be weakly active compounds. Moderately active compounds have a 4-hydroxyl substituted benzene ring with a hydrophobic moiety equivalent in size and shape to the B- and C-ring of 17 beta-estradiol, or have a high hydrogen-bond donor capacity owing to the presence of halogens on a nonphenolic ring. Strongly active compounds, similar to 4,4'-diethylethylene bisphenol (DES), possess the same hydrophobic ring structure as des




Anticancer Res. 2001 Sep-Oct;21(5):3215-20.
Effects of 17beta-estradiol administration on apoptosis and polyamine content in AGS cell line.

Pricci M, Linsalata M, Russo F, Messa C, Amati L, Caradonna L, Jirillo E, Di Leo A.

Laboratory of Biochemistry, Scientific Institute for Digestive Diseases-IRCCS Saverio de Bellis, Bari, Italy.

BACKGROUND: Estrogens and polyamines seem to play an important role not only in cell growth and differentiation, but also in programmed cell death. The aim of the present study was to investigate the effects of 17beta-estradiol supplementation on apoptosis as well as on the polyamine content of an ER-positive human gastric cancer cell line (AGS). MATERIALS AND METHODS: Apoptosis was investigated by evaluating DNA fragmentation, using enzyme immunoassay and agarose gel electrophoresis and the phosphatidylserine exposure by flow cytometry analysis. Polyamine levels were evaluated by HPLC. RESULTS: 17Beta-estradiol gave rise to a marked pro-apoptotic effect at concentrations of 16 microM or higher compared to the control. Moreover, the hormone significantly reduced the contents of polyamines compared to control cells. The apoptotic effect of 17beta-estradiol was partially counteracted by exogenous spermine administration. CONCLUSION: 17Beta-estradiol administration induces apoptosis in AGS cells. Further, an increase in cell sensitivity to apoptosis due to a decline in the polyamine content may be suggested.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11848475&dopt=Abstract estradiol




J Steroid Biochem Mol Biol. 2003 Feb;84(2-3):269-78.
Growth inhibition of multi-drug-resistant breast cancer cells by 2-methoxyoestradiol-bis-sulphamate and 2-ethyloestradiol-bis-sulphamate.

Suzuki RN, Newman SP, Purohit A, Leese MP, Potter BV, Reed MJ.

Endocrinology and Metabolic Medicine and Sterix Ltd., Faculty of Medicine, Imperial College, St. Mary's Hospital, London W2 1NY, UK.

There is currently considerable interest in the use of the endogenous oestrogen metabolite, 2-methoxyoestradiol (2-MeOE2) for the treatment and prevention of breast cancer. We have previously shown that sulphamoylation of 2-MeOE2 and related derivatives greatly enhances their ability to inhibit the proliferation of ER+ and ER- breast cancer cells. In this study, we have compared the abilities of 2-methoxyoestradiol-bis-sulphamate (2-MeOE2bisMATE) and 2-ethyloestradiol-bis-sulphamate (2-EtE2bisMATE) with that of 2-MeOE2 to inhibit the proliferation of breast cancer cells when grown on three different substrata: plastic, collagen I and Matrigel. The human breast cell line MCF-7 was utilised for these studies together with its doxorubicin resistant variant, MCF-7 DOX40 and mitoxantrone resistant variant, MCF-7 MR, as a longitudinal model of in vitro drug resistance. On a plastic substratum all three cell lines were sensitive to the effects of 2-MeOE2bisMATE and 2-EtE2bisMATE whereas MCF-7 cells and the MCF-MR variant cells were resistant to the effects of 2-MeOE2 at 1 microM. The sensitivity of the cell lines to those compounds also remained significant when grown on more physiological substrata. All of the drugs tested arrested cells in the G2/M phase of the cell cycle. The finding that breast cancer cells that are resistant to conventional chemotherapeutic agents remain sensitive to 2-substituted oestrogen sulphamates offers considerable potential for the treatment of women with drug-resistant breast cancer.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12711013&dopt=Abstract estradiol




Bone. 2002 Feb;30(2):393-8.
2-methoxyestradiol induces interferon gene expression and apoptosis in osteosarcoma cells.

Maran A, Zhang M, Kennedy AM, Sibonga JD, Rickard DJ, Spelsberg TC, Turner RT.

Department of Orthopedics, Mayo Foundation, MN, Rochester 55905, USA. maraayo.edu

2-Methoxyestradiol (2-ME), a naturally occurring mammalian metabolite of 17beta-estradiol, has been implicated as a physiological inhibitor of tumor cell proliferation. In this study, the effects of 2-ME on cultured osteosarcomatous cells were investigated. Dose-dependent growth inhibition was observed in MG63 and TE85 human osteosarcoma cells exposed to 2-ME. The cell killing by 2-ME was ligand-specific; the immediate precursor (2-hydroxyestradiol), the parent compound (17beta-estradiol), and the equivalent metabolite of estrone (2-methoxyestrone) exhibited less potency and efficacy. Furthermore, 2-ME was similarly effective at killing immortalized human fetal osteoblastic cells (hFOB) with and without estrogen receptor-alpha and -beta and rat osteosarcoma cells (ROS17/2.8). The cytotoxicity of 2-ME was selective to transformed and immortalized osteoblastic cells; 2-ME (2 microm) had no effect on the proliferation of primary cultures of human osteoblasts. Co-treatment with the potent estrogen receptor ligand, ICI-182,780, did not reduce 2-ME-induced osteosarcoma cell death, implying that this action is not mediated by conventional estrogen receptors. The expression levels of bone matrix protein genes, type 1 collagen and osteonectin, were transiently reduced after 2-ME treatment, suggesting that the surviving cells are capable of producing bone matrix. The 2-ME-mediated killing of osteosarcoma cells was due to the induction of apoptosis; treatment induced expression of interferon genes within 12 h and histological evidence of apoptosis within 48 h of 2-ME treatment. Thus, our results demonstrate that 2-ME is highly cytotoxic to osteosarcoma cells but not normal osteoblasts. These findings suggest tha




Br J Cancer. 2002 Jan 7;86(1):136-42.
17beta-Oestradiol treatment modulates nitric oxide synthase activity in MDA231 tumour with implications on growth and radiation response.

Chinje EC, Williams KJ, Telfer BA, Wood PJ, van der Kogel AJ, Stratford IJ.

Experimental Oncology Group, School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK. edwin.chinjan.ac.uk

The putative oestrogen receptor negative human breast cancer cell line MDA231, when grown as tumours in mice continually receiving 17beta-oestradiol, showed substantially increased growth rate when compared to control animals. Further, we observed that 17beta-oestradiol treatment could both increase the growth rate of established MDA231 tumours as well as decreasing the time taken for initiating tumour growth. We have also demonstrated that this increase in growth rate is accompanied by a four-fold increase in nitric oxide synthase activity, which was predominantly the inducible form. Inducible-nitric oxide synthase expression in these tumours was confirmed by immunohistochemical analysis and appeared localized primarily in areas between viable and necrotic regions of the tumour (an area that is presumably hypoxic). Prophylactic treatment with the nitric oxide synthase inhibitor nitro-L-arginine methyl ester resulted in significant reduction in this apparent 17beta-oestradiol-mediated growth promoting effect. Tumours derived from mice receiving 17beta-oestradiol-treatment were characterized by a significantly lower fraction of perfused blood vessels and an indication of an increased hypoxic fraction. Consistent with these observations, 17beta-oestradiol-treated tumours were less radio-responsive compared to control tumours when treated with a single radiation dose of 15 Gy. Our data suggests that long-term treatment with oestrogen could significantly alter the tumour oxygenation status during breast tumour progression, thus affecting response to radiotherapy.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11857025&dopt=Abstract estradiol




J Dairy Sci. 2002 Jan;85(1):68-78.
Development and validation of a short-term, serum-free culture system for bovine granulosa cells: evaluation of the effects of somatotropin and growth hormone-releasing factor on estradiol production.

Jimenez-Krassel F, Ireland JJ.

Department of Animal Science, Michigan State University, East Lansing 48824, USA. Jimenezmsu.edu

The objective of this study was to develop and validate a short-term, serum-free culture system to determine whether recombinant bovine somatotropin (rbST) or recombinant bovine growth hormone-releasing factor (rbGRF) altered the estradiol-producing capacity of bovine granulosa cells isolated from dominant or subordinate follicles of the first follicular wave. Thus, ovaries were obtained at an abattoir from cows that were between d 2 to 5 or 6 to 10 of the estrous cycle. Three size classes of follicles were isolated from each cow's ovaries: small (2 to 5 mm in diameter), medium (6 to 14 mm), or the largest (6 to 19 mm). In vivo steroid-producing capacity of follicles was assessed by measuring concentration of estradiol, progesterone, androstenedione and 5alpha-dihydrotestosterone in each follicle. In vitro steroid-producing capacity was assessed by culturing granulosa cells from the different follicle sizes for 48 h in serum-free media with 19-OH androstenedione and measuring the estradiol and progesterone concentrations in media at the end of culture. The effect of different doses of FSH, rbST, or rbGRF on estradiol and progesterone production by granulosa cells from each follicle size class during d 2 to 5 or 6 to 10 was also evaluated. A high percentage (91.7%) of the largest follicles obtained on d 2 to 5 was estrogen-active (estradiol > progesterone) compared with other follicle classifications (d 2 to 5, small = 0%, medium = 13.8%; d 6 to 10, small = 0%, medium = 3.3%, largest = 33.3%). Estradiol was highest (P < 0.05) in the largest follicle on d 2 to 5 and correlated positively with follicle diameter. The pattern