Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Estrogen Receptor Modulators”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources
PubMed1994

RU486 exerts antiestrogenic activities through a novel progesterone receptor A form-mediated mechanism.

The human progesterone receptor (hPR) exists in two distinct forms in most cells, hPR-A and hPR-B. Both receptor isoforms exhibit distinct biological functions and demonstrate a cell- and promoter-specific ability to regulate gene transcription. Interestingly, in cell contexts where PR-A is transcriptionally inactive, it acts as a progesterone-dependent inhibitor of estrogen receptor function. Coexpression of the human estrogen receptor with the A form (but not the B form) of the human progesterone receptor resulted in a ligand-dependent inhibition of estrogen receptor-mediated gene transcription. The antiprogestins RU486 (MIfepristone) and ZK98299 (Onapristone) and related antiprogestins were all effective "noncompetitive" inhibitors of the estrogen receptor in this assay as none of these compounds interacted directly with the estrogen receptor. This observation may explain in part the observed tissue-specific antiestrogenic effects of RU486 and further indicates that the antiestrogenic activities of antiprogestins may be intrinsic to their biological function. This important new information defines novel activities of progesterone receptor ligands and may alter the way in which we define progesterone receptor modulators for future clinical applications. In addition, these data reveal that the A form of the progesterone receptor plays a key role in modulating estrogen receptor function in cells where both receptors are expressed.

Animals↗
PubMed2004

Cardiovascular effects of raloxifene: the arterial and venous systems.

BACKGROUND: Cardiovascular disease caused by atherosclerosis is the largest single killer of women. Prior observational data had suggested that hormone therapy may have cardioprotective effects. METHODS: Data from clinical trials and basic science studies were evaluated to assess the cardiovascular effects of hormone therapy and selective estrogen replacement modulators. RESULTS: Hormone therapy does not appear to lower the risk of cardiovascular events in older postmenopausal women. Selective estrogen receptor modulators (SERMS) have been approved for human use; tamoxifen is used for treatment and prevention of breast cancer and raloxifene is used for the treatment and prevention of osteoporosis. Raloxifene is the only SERM being specifically studied for its effects on coronary heart disease events in a prospective, randomized, controlled trial. CONCLUSIONS: Although raloxifene does increase venous thromboembolic events, there is suggestive data that it may have favorable effects on the arterial systems in women. Only compelling positive data from the Raloxifene Use for The Heart (RUTH) trial will lead to greater use of SERMS to potentially lower the risk of atherosclerotic vascular disease.

Arteries↗
PubMed2004

[Defining the role of raloxifene as a therapeutic agent for postmenopausal osteoporosis: focus on its pharmacological properties].

In this semiar, I propose to describe the pharmacological properties of raloxifene that provide a basis for its role in the treatment of postmenopausal osteoporosis. These pharmacological properties can be described as providing therapeutic benefits in the following three areas: 1) reduction in bone turnover, 2) increases in bone mineral density, and 3) risk reduction in fractures. While reloxifene shares these effects with conventional bisphosphonates that are in common use for postmenopausal osteoporosis, it exerts its antiresorptive effects through a different mechanism of action from those of the bisphosphonates. Furthermore, raloxifene exerts its stimulatory or inhibitory effects on estrogen in a tissue-specific fashion as a selective estrogen-receptor-modulator (SERM), thereby providing a wide range of clinical benefits that result from its ability to exert estrogen-like beneficial effects in tissues other than bone while at the same time inhibiting estrogen-like deleterious effects in other tissues. I therefore propose to define the role of raloxifene as a viable therapeutic option in the treatment of postmenopausal osteoporosis in light of these unique pharmacological features. Current data suggests that raloxifene can be positioned somewhere in between hormone replacement therapy (HRT) and bisphosphonates, and is highly likely to be suitable for use in patients between the ages of 55 and 70, while other agents may be indicated in special populations, such as premenopausal patients, postmenopausal patients with hot flushes, or elderly patients who may be placed at accelerated risk of developing femoral neck fractures. Thus, as a novel therapeutic option with unique clinical benefits, a far greater role may be expected for raloxifene in the treatment of postmenopausal osteoporosis than for other conventional therapeutic agents.

Biomarkers↗
PubMed2000

Endocrine therapy for breast cancer.

In addition to ovarian ablation by means of surgery or irradiation, a wide variety of endocrine agents are now available for the management of breast cancer, in both the metastatic and adjuvant settings. Currently available endocrine agents include antiestrogens, progestational drugs, and aromatase inhibitors. Randomized trials and meta-analyses have greatly clarified the specific roles of the more established of these agents in both premenopausal and postmenopausal women. However, the exact combination and sequence of these drugs are still under investigation. The addition of the bisphosphonates has also helped improve the quality of life of patients with metastatic disease. Among new endocrine agents currently under development are the pure antiestrogens, selective estrogen receptor modulators (SERMs), and a group of drugs with effects intermediate between the two.

Antineoplastic Agents, Hormonal↗
PubMedDate not supplied

Estradiol and raloxifene decrease the formation of multinucleate cells in human bone marrow cultures.

Estrogen (E2) deficiency is responsible for increased bone turnover in the postmenopausal period, and it can be prevented by estrogen replacement therapy. The way estrogen acts on bone cells is not fully understood. Human bone marrow cell cultures may be a reliable model for studying the action of steroids on osteoclastogenesis in vitro. We examine the effects of estradiol and Raloxifene, a selective estrogen receptor modulator, on human primary bone marrow cells cultured for 15 days. 17beta-estradiol and Raloxifene significantly decreased the number of tartrate-resistant acid phosphatase multinucleate cells from osteoclast precursors on day 15. Estrogen receptor alpha (ER-alpha) mRNA was present in bone marrow mononuclear cells cultured for 5 days, but there was no estrogen receptor beta (ER-beta) mRNA, suggesting that this effect was mediated by ER-alpha. 15-day cultures no longer contained ER-alpha mRNA, suggesting that estrogen acts on early events of osteoclast differentiation. Finally, 10-8 M 17beta-estradiol has no effect on the release of IL-6 and IL-6-sr into the medium of marrow mononuclear cells cultured for 5 or 15 days. Osteoclast apoptosis was not affected by estradiol or Raloxifene after 15 days of culture under our conditions. In conclusion, we have shown that both estradiol and Raloxifene inhibit osteoclast differentiation in human bone marrow mononuclear cultures. The biological effect that can mimic in vivo differentiation could be mediated through ER-alpha.

Apoptosis↗
PubMed2000

[Drug treatment for the treatment of primary osteoporosis].

The goal of drug treatment of osteoporosis is to prevent fractures. Increase of bone density during therapy is not consistently associated with a clinical benefit. The purpose of this paper is to review the evidence of fracture prevention from published randomized controlled trials. Vitamin D, the bisphosphonate alendronate and the selective estrogen receptor modulator raloxifene have been evaluated in large randomized trials with clinical endpoints.

Alendronate↗
PubMedDate not supplied

Estradiol, but not raloxifene, improves aspects of spatial working memory in aged ovariectomized rhesus monkeys.

Estrogen replacement therapy (ERT) alleviates many postmenopausal symptoms but whether it also benefits cognitive function remains controversial. Further, since estrogen increases the risk of breast and uterine cancers, a new class of compounds, called selective estrogen receptor modulators (SERMs) is being considered as possible alternative to ERT. The SERM raloxifene is particularly interesting because, like estrogen, it improves lipid metabolism and reduces bone loss, without adverse effects on the breast or uterus. Little is known, however, about its effect upon cognitive function. We used a rhesus monkey model of human menopause to examine the effects of ERT and raloxifene on cognitive function. We tested 5 aged females (21-24 years old) ovariectomized long-term (10-16 years) on a battery of age-sensitive tasks, including the Delayed Response (DR), the Delayed Non-Matching-to-Sample-10 min (DNMS-10 min) and the spatial-Delayed Recognition Span Test (DRST). Monkeys were tested 5 days a week on each task for 9 consecutive months, while undergoing treatments with placebo, ethinyl estradiol (EE(2)), and raloxifene in alternating 28-days blocks. EE(2) transiently enhanced the working memory component of the spatial-DRST, but did not affect performance on the other tasks of the battery. Raloxifene had no effect on cognitive performance. These findings indicate that estradiol is able to enhance some aspects of spatial working memory in aged monkeys despite many years of estrogenic deprivation. Further, they suggest that raloxifene does not affect cognitive function after long-term ovarian hormone deprivation.

Aging↗
PubMed1999

Modification of serum lipids and cardiovascular risk by estrogenic active compounds.

Cardiovascular disease is an important cause of death among women. After the menopause there is a steep elevation of low-density lipoprotein (LDL) cholesterol and lipoprotein(a) concomitantly with other risk factors, followed by a striking increase in arteriosclerotic vascular disease, compatible with a lack of estrogens as a causative factor. The benefit of hormone replacement therapy has been documented in several large studies, although rigorous randomized trials are still under way. However, cardiovascular events have been reduced by approximately 50%. In order to optimize beneficial effects and minimize side-effects, the characteristics of selective estrogenic active compounds are a major target of research. The anti-estrogens are the prototype of partial and selective estrogen functions. The components of conjugated estrogens are under investigation for their specific effects. For example, both 17 alpha-dihydroequilin sulfate and 17 alpha-dihydroequilenin sulfate seem to exert antioxidant activity without significant proliferative effects on uterine or breast tissues. This suggests a selective estrogenic activity dependent on the predominant type of estrogen receptor in the particular tissue. Equilin sulfate exerts a significantly stronger antioxidant activity than 17 beta-estradiol in vitro, and delta 8-estrone sulfate increases the lag time for low-density lipoprotein oxidation in vivo. These actions on lipoproteins may add to the quantitative changes of lipoproteins, while other effects are independent of lipoproteins. The 17 alpha-dihydroequilin sulfate and equilin sulfate improved the action of insulin in vivo. Data from rhesus monkeys treated with 17 alpha-dihydroequilenin sulfate indicate that additional mechanisms are probably responsible for the observed cardiovascular protection. Further studies need to be conducted in order to identify selective estrogen receptor modulators and assess their potential, especially in lowering cardiovascular risk.

Aged↗
PubMed2004

Role of raloxifene in breast cancer prevention in postmenopausal women: clinical evidence and potential mechanisms of action.

BACKGROUND: Raloxifene is a selective estrogen-receptor modulator (SERM) indicated for the prevention and treatment of osteoporosis in postmenopausal women. In the Multiple Outcomes of Raloxifene Evaluation (MORE) study, an osteoporosis treatment trial, raloxifene therapy was associated with a reduced incidence of invasive, estrogen receptor (ER)-positive breast cancer compared with placebo (relative risk, 0.16; 95% CI, 0.09-0.30). OBJECTIVE: This review summarizes available preclinical and clinical data pertaining to a potential role for raloxifene in the prevention of breast cancer, and examines the mechanisms of action by which raloxifene may exert an effect. METHODS: Relevant articles were identified through a search of MEDLINE for English-language studies published between 1966 and January 2003. Search terms included raloxifene, keoxifene, tamoxifen, SERM, estrogen, estrogen receptor, breast, mammary, growth factors, and apoptosis. The reference lists of identified articles were reviewed for additional publications. RESULTS: Both preclinical and clinical data suggest a role for raloxifene in the prevention of breast cancer. Like tamoxifen, raloxifene acts as an estrogen antagonist in breast tissue through competitive binding to the ER. Raloxifene may also inhibit breast tissue proliferation through mechanisms independent of the ER. CONCLUSIONS: Given raloxifene's mechanism of action and the preclinical evidence for its role in breast cancer prevention, a clinically favorable effect seems feasible. Results of ongoing clinical studies will provide evidence to support or refute the clinical findings of MORE and thus raloxifene's role in the breast cancer prevention.

Aged↗
PubMed2000

Breast cancer chemoprevention.

Chemoprevention of breast cancer is a rapidly growing field. Chemoprevention was initiated with the development of the antiestrogen tamoxifen. A major clinical trial in the United States found that tamoxifen reduced the incidence of breast cancer by almost 50% in women at an increased risk for the disease. Although two European trials did not confirm these findings, the Food and Drug Administration found the American studies significant enough to approve tamoxifen for the delaying of breast cancer in women at high risk for the disease. However, adverse effects associated with tamoxifen include a minimally increased rate of endometrial cancer, cataracts, and strokes. Newer classes of antiestrogens, called selective estrogen receptor modulators (SERMs), are being investigated as potential chemopreventive agents. These SERMS, such as raloxifene, will hopefully provide some of the benefits of estrogen without its inherent risks. In addition, naturally occurring compounds and their analogues are also under investigation.

Adult↗
PubMed2001

Effects of estrogen deficiency on brain function. Implications for the treatment of postmenopausal women.

A growing body of evidence suggests that postmenopausal estrogen deficiency accelerates brain aging and increases the risk of various neurodegenerative processes, including Alzheimer's disease. Recent preclinical and clinical studies have indicated that estrogen has positive effects on brain homeostasis by preserving neural plasticity and the neurotransmitter pathways involved in learning, memory, and balance. In this article, Dr Birge and his coauthors address the effects of estrogen on brain function and discuss their implications for the use of selective estrogen receptor modulators, particularly tamoxifen and raloxifene, in postmenopausal women.

Aging↗
PubMed2003

Raloxifene lowers IGF-I levels in acromegalic women.

BACKGROUND: IGF-I suppression in acromegaly obtained by tamoxifen, a selective estrogen receptor modulator (SERM), prompted us to evaluate the effects of the administration of a newer SERM, raloxifene (RAL), devoid of estrogenic activity at uterine level, on GH/IGF-I levels in patients with this disease. PATIENTS: Thirteen post-menopausal acromegalic women (aged 55-84 years) with active acromegaly entered a prospective open pilot study of RAL treatment at 60 mg/day. Nine of the patients, who were resistant to somatostatin analog and dopamine agonist treatment, were not undertaking therapy; the other four, who were partially sensitive to medical treatment, maintained treatment at the maximally effective dosages throughout the study. RESULTS: IGF-I levels fell significantly from 444 (median, interquartile 393-590) microg/l to 300 (216-608) microg/l (P=0.0192) after 1 month of RAL administration and this fall remained stable up to the final evaluation at 5+/-1 months from the start of RAL treatment (260 (187-410) microg/l). An IGF-I decrease greater than 30% of basal values was observed in 10 patients (mainly in patients with IGF-I levels lower than 600 microg/l) and normal values were reached in seven (54%). GH levels did not change (basal 6 (4.1-8) microg/l, final 5.5 (3.2-7.4) microg/l). The clinical picture improved in patients sensitive to RAL. RAL withdrawal was followed by the return of IGF-I levels to pretreatment values within 8 weeks in all patients. CONCLUSIONS: RAL decreases IGF-I levels in most acromegalic women with mild or intermediate disease (i.e. with values lower than 600 microg/l) and normalizes it in many. A prospective randomized study in patients resistant or partially sensitive to other medical treatments is warranted.

Acromegaly↗
PubMed2001

Digitized mammography: a clinical trial of postmenopausal women randomly assigned to receive raloxifene, estrogen, or placebo.

BACKGROUND: High mammographic density is associated with increased breast cancer risk. Previous studies have shown that estrogens increase breast density on mammograms, but the effect on mammographic density of selective estrogen receptor modulators, such as raloxifene, is unknown. We assessed changes in mammographic density among women receiving placebo, raloxifene, or conjugated equine estrogens in an osteoporosis prevention trial. METHODS: In a 5-year multicenter, double-blind, randomized, placebo-controlled osteoporosis prevention trial, healthy postmenopausal women who had undergone hysterectomy less than 15 years before the study and had no history of breast cancer received placebo, raloxifene (at one of two doses), or conjugated estrogens (ERT). Women from English-speaking investigative sites who had baseline and 2-year craniocaudal mammograms with comparable positioning (n = 168) were eligible for this analysis. Changes in mammographic density were determined by digital scanning and computer-assisted segmentation of mammograms and were analyzed with the use of analysis of variance. All statistical tests were two-sided. RESULTS: Among the four treatment groups after 2 years on study, the mean breast density (craniocaudal view) was statistically significantly greater in the ERT group than it was in the other three groups (P<0.01 for all three comparisons). Within treatment groups, the mean breast density from baseline to 2 years decreased statistically significantly in women receiving the placebo or either the higher or lower raloxifene dose (P = 0.003, P = 0.002, and P<0.001, respectively) and showed a nonstatistically significant increase in women receiving ERT. CONCLUSIONS: In an osteoporosis prevention trial, raloxifene did not increase breast density after 2 years of treatment. Raloxifene administration should not interfere with, and could even enhance, mammographic detection of new breast cancers.

Breast↗
PubMed2004

Potential role of a novel transcriptional coactivator PELP1 in histone H1 displacement in cancer cells.

The estrogen receptor plays an important role in breast cancer progression. Proline-, glutamic acid-, and leucine-rich protein 1 (PELP1), also called modulator of nongenomic activity of estrogen receptor (MNAR), a novel coactivator of estrogen receptor, modulates estrogen receptor transactivation functions. The mechanisms by which PELP1 modulates estrogen receptor genomic functions is not known. Here, using biochemical and scanning confocal microscopic analysis, we have demonstrated nuclear localization and functional implications of PELP1. Subnuclear fractionation showed PELP1 association with chromatin and nuclear matrix fractions. Ligand stimulation promoted recruitment of PELP1 to 17beta-estradiol responsive promoters, its colocalization with acetylated H3, and increased PELP1-associated histone acetyltransferase enzymatic activity. Far Western analysis revealed that PELP1 interacts with histone 1 and 3, with more preference toward histone 1. Using deletion analysis, we have identified the PELP1 COOH-terminal region as the histone 1 binding site. The PELP1 mutant lacking histone 1-binding domain acts as a dominant-negative and blocks estrogen receptor alpha-mediated transcription. Chromatin immunoprecipitation analysis showed a cyclic association and dissociation of PELP1 with the promoter, with recruitment of histone 1 and PELP1 occurring in opposite phases. PELP1 overexpression increased the micrococcal nuclease sensitivity of estrogen response element-containing nucleosomes. Our results provide novel insights about the transcription regulation of PELP1 and suggest that PELP1 participates in chromatin remodeling activity via displacement of histone 1 in cancer cells.

Bone Neoplasms↗
PubMed2001

Estrogen suppression of EGFR expression in breast cancer cells: a possible mechanism to modulate growth.

Epidermal growth factor receptor (EGFR) is a transmembrane receptor whose overexpression in breast cancer predicts for poor prognosis and is inversely correlated with expression of estrogen receptor (ER). This study was designed to investigate whether estrogen plays an active role in suppression of EGFR expression in estrogen-responsive breast cancer cell lines expressing low levels of EGFR. Upon withdrawal of estrogen, EGFR mRNA and protein increased 3-6 fold in MCF-7, T47D, and BT474 ER+ breast cancer cells. This was reversible upon addition of estradiol back to the culture media, but only after prolonged treatment. Nuclear run-on assays and studies with the transcription inhibitor actinomycin D demonstrated that regulation is at the transcriptional level. These results indicate that in the presence of estrogen, ER+ breast cancer cells possess active mechanisms to suppress EGFR expression. Up-regulation of EGFR in response to estrogen depletion and growth inhibition could represent an attempt to rescue cell growth by utilizing an alternative pathway. Indeed, we found that estrogen-depleted breast cancer cells are more sensitive to the mitogenic effects of EGF and TGF-alpha, and simultaneous blockade of both estrogen and EGFR signaling pathways induced cell death. J. Cell. Biochem. Suppl. 36: 232-246, 2001.

Blotting, Western↗
PubMed2003

Tamoxifen and ICI 182,780 negatively influenced cardiac cell growth via an estrogen receptor-independent mechanism.

BACKGROUND: Recent studies have demonstrated that selective estrogen receptor modulators (SERMs) reduced identifiable risk factors implicated in cardiovascular disease. Despite this observation, the direct effect of SERMs on cardiac cell growth remains unexplored. METHODS: Neonatal rat cardiac myocytes (CM) and fibroblasts (CF) were exposed to either the partial estrogen receptor agonist/antagonist 4-OH tamoxifen (e.g., SERM) or the pure estrogen receptor antagonist ICI 182,780 and the effect on DNA synthesis, cell cycle protein expression and extracellular signal-regulated kinase (ERK1/2) phosphorylation were assessed. RESULTS: The treatment of CM and CF with either 4-OH tamoxifen or ICI 182,780 decreased DNA synthesis in the absence of apoptosis via an estrogen receptor-independent pathway. In CM and CF, 4-OH tamoxifen and ICI 182,780 treatment reduced proliferating cell nuclear antigen protein expression and concomitantly increased p27Kip1. 4-OH Tamoxifen and ICI 182,780 treatment increased ERK1/2 phosphorylation in CM and CF, and ERK1/2 kinase (MEK)-dependent inhibition of ERK1/2 activation attenuated ICI 182,780-mediated suppression of DNA synthesis. CONCLUSION: These data are the first to describe cardiac cells as novel targets of SERMs and ICI 182,780, and highlight the role of the ERK1/2 pathway in the suppression of DNA synthesis.

Analysis of Variance↗
PubMed2001

Estrogen augments glucose transporter and IGF1 expression in primate cerebral cortex.

Estrogen has many positive effects on neural tissue in experimental model systems, including stimulation of neurite growth and neurotransmitter synthesis and protection against diverse types of neural injury. In humans, estrogen treatment is reputed to protect against Alzheimer's disease. To investigate potential mediators of estrogen's action and determine whether selective estrogen receptor modulators (SERMs) such as tamoxifen have estrogen-like effects in the primate brain, we evaluated the expression of glucose transporters and insulin-like growth factor 1 (IGF1) and its receptor in the frontal cortex of ovariectomized rhesus monkeys. We treated one group for 3 days with vehicle, another with 17 beta estradiol (E2), and a third with tamoxifen. The expression of facilitative glucose transporters (Gluts) 1, 3, and 4 was investigated using in situ hybridization, immunohistochemistry, and immunoblot analysis. Gluts 3 and 4 were concentrated in cortical neurons and Glut1 in capillaries and glial cells. E2 treatment induced two- to fourfold increases in Glut3 and Glut4 mRNA levels and lesser but significant increases in Glut3 and 4 protein levels. E2 treatment induced an approximately 70% increase in parenchymal Glut1 mRNA levels, but did not appreciably affect vascular Glut1 gene expression. IGF1 and IGF1 receptor mRNAs were concentrated in cortical neurons in a distribution similar to Gluts 3 and 4. IGF1 mRNA levels were significantly increased in E2-treated animals but IGF1 receptor mRNA levels were not altered by hormone treatment. Tamoxifen increased cerebral cortical Glut3 and 4 mRNA levels, but did not affect Glut1, IGF1, or IGF1 receptor expression. This study provides novel data showing that Gluts 3 and 4 and IGF1 are coexpressed by primate cerebral cortical neurons, where their expression is enhanced by estrogen. These findings suggest that up-regulation of glucose transporter and IGF1 expression may contribute to estrogen's salutary effects on neural tissue. Tamoxifen, an antiestrogen at the breast, is shown to have estrogen-like effects on higher brain centers in the monkey, suggesting that some SERMs may share estrogen's neuroprotective potential for menopausal women.

Animals↗