PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Selective Estrogen Receptor Modulators”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 937 records · Page 52Linked to original sources

Menopause and the central nervous system: intervention options.

The central nervous system is an important target for sex steroid hormones. During the climateric period the rapid decline of gonadal steroids causes neuroendocrine changes in different areas of the brain. The failure of gonadal hormone production brings specific symptoms due to the central nervous system derangement. At the hypotalamic level estrogen withdrawal gives rise to vasomotor symptoms, eating behavior disorders and altered blood pressure control. Psychological disturbances such as depression, anxiety, irritability and mood fluctuation are related to estrogen-induced changes in the lymbic system. The hypothesis of specific neuroanatomical and neurophysiological effects of estrogen on the brain may also explain the correlation between estrogen deficiency and cognitive disturbances such as Alzheimer's type dementia (AD). The increasing interest in the influence of sex steroids on brain function has focused attention on hormonal replacement therapy. Clinical and epidemiological studies have demonstrated that estrogen therapy exerts a positive effect on vasomotor instability and improves psychological disturbances. The positive effects of estrogen on mood are probably related to its stimulatory action on adrenergic and serotoninergic tone. Estrogen may influence the cognitive function through different biological actions. Estrogen administration increases total cerebral and cerebellar blood flow, cerebral glucose administration and improves cholinergic tone, a key neurotransmitter in learning and memory. The evidence suggests that hormone replacement therapy may reduce the relative risk of developing AD. Progestagens and androgen may also have a role in the control of mood disorders. At present, few data are available regarding the influence that selective estrogen receptor modulators, a new class of compounds, can exert on the brain.

Alzheimer Disease↗

Hormonal replacement regimens and bleeding.

Hormone replacement therapy may increase the quality of life of postmenopausal women. Any regimen need to offer long-term endometrial safety. It is a standard to consider the co-administration of a sequential progestogen when estrogen replacement should be initiated in non-hysterectomized women. It is almost impossible to decide which combination of an estrogen and a progestogen seems to be optimal as individual tolerance of HRT may very well limit acceptability despite metabolic benefits and proven endometrial safety of a given combination. Several combinations of oral and transdermal estradiol or conjugated equine estrogens, oral progestogens, transdermal norethisterone acetate and levonorgestrel, and intrauterine levonorgestrel may achieve endometrial safety. It is noteworthy that there is no uniform correlation between the timing of onset of bleeding induced by any sequential estrogen and progestogen replacement and a certain pattern of histology. Therefore, although it is likely, there is no absolute reassurance that regular bleeding on or after day 11 of progestogen administration rules out abnormal histopathology. Transvaginal sonography seems not to be of pivotal importance to screen asymptomatic women on replacement therapy for detection of serious abnormal endometrial findings such as hyperplasia and endometrial cancer. Continuous combined hormone replacement therapy or the use of tibolone may be an alternative in postmenopausal women, who do not want any uterine bleedings after menopause. However, spottings or bleedings most often occur at the beginning of treatment. Vaginal administration of estriol and estradiol for urogenital symptoms of estrogen deficiency may stimulate the endometrium unintentionally. Available data suggest that use of oral estriol may be associated with endometrial hyperplasia and endometrial carcinoma relatively more often compared to sequential HRT. Raloxifene, a benzothiophene derivative acting as a selective estrogen receptor modulator approved for prevention of vertebral osteoporosis, rarely causes uterine bleeding. There is no ideal therapy available to suit women looking for a permanently bleed-free hormonal replacement therapy today.

Administration, Intravaginal↗

Theoretical basis for the benefit of postmenopausal estrogen substitution.

Women are being presented with an increasing number of choices for health care management as they move through the aging process. Estrogen has positive effects on mood, sexual function, target end organs and cognitive function, and may play an important role in the etiology of Alzheimer's Disease by acting to prevent amyloid plaque formation, oxidative stress, or deterioration of the cholinergic neurotransmitter system. The benefits of estrogen therapy for osteoporosis, the cardiovascular system, and lipid metabolism are far reaching, but the possibility of developing breast cancer later in life is also relevant. Understanding the mechanisms for the action of the estrogens, anti-estrogens, and the selective estrogen receptor modulators, and possible alternative routes of symptom management for some menopausal events is important to make appropriate decisions on choice of therapy. This review discusses the theoretical basis for estrogen's actions in the management of the postmenopausal stage of the life cycle.

Alzheimer Disease↗

Soy isoflavones' osteoprotective role in postmenopausal women: mechanism of action.

Ovarian hormone deficiency is a major risk factor for osteoporosis. Current therapies emphasize the use of antiresorptive agents, such as estrogen, calcitonin, and bisphosphonates. These therapies are associated with certain risks and side effects making compliance a major obstacle. Recent findings suggest that a class of synthetic and naturally occurring compounds, selective estrogen receptor modulators, e.g. raloxifene and soy isoflavones can offer attractive alternatives. Evidence for bone-sparing effects of isoflavones relies mainly on animal findings supported by a limited number of human studies. These observations suggest that isoflavones exert their effects on bone by stimulating bone formation and at the same time suppressing bone resorption. However, the precise osteoprotective mechanism of isoflavones remains uncertain and awaiting further clarification. From a clinical point of view, larger and longer duration studies are warranted to enable us to draw clear conclusions in regards to the role of isoflavones on bone.

Journal Article↗

Prevention of bone loss by EM-800 and raloxifene in the ovariectomized rat.

Some undesirable effects are associated with chronic estrogen and progestin administration used to prevent bone loss in postmenopausal women, thus leading to poor compliance and the need for improved therapeutic and preventive agents. We have thus studied the ability of the new antiestrogen EM-800 (SCH 57050) to prevent bone loss and lower serum cholesterol levels and compared its effects with those of raloxifene. Ovariectomized (OVX) female rats were treated by oral gavage for 37 weeks with increasing daily doses (0.01, 0.03, 0.1, 0. 3 or 1 mg/kg) of EM-800 or raloxifene. At 35 weeks after OVX, lumbar spine bone mineral density (BMD) was 19% lower than in intact animals (P<0.01), while the OVX animals given EM-800 or raloxifene had 90-93 and 85-90%, respectively, of the BMD values observed in intact rats. Similar effects were observed on femoral BMD. Bone histomorphometry measurements were performed on proximal tibia. At the 0.01 mg/kg dose, EM-800 prevented the effect of OVX on TBV by 34% (P<0.01), while raloxifene had no detectable effect. Treatment with 1 mg/kg EM-800 and raloxifene resulted in, respectively, 68% (P<0.01) and 64% (P<0.01) prevention of the OVX-induced decrease in TBV. In addition, the administration of 0.01 and 0.03 mg/kg EM-800 caused, respectively, 54% (P<0.01) and 56% (P<0.01) inhibitions of serum cholesterol levels, while raloxifene administered at the same doses caused, respectively, 24% (P<0.01) and 41% (P<0.01) decreases of the value of the same parameter. At the highest doses used (0.1-1 mg/kg), both compounds lowered serum cholesterol levels by approximately 65% (P<0.01). No stimulatory effect of EM-800 was observed on the endometrial epithelial cells at doses up to 1 mg/kg, while hypertrophy of uterine epithelium was observed with raloxifene. EM-800 and raloxifene achieve the same degree of effectiveness on bone and serum cholesterol at higher doses, but EM-800 is at least three to ten times more potent than raloxifene at lower concentrations and has no stimulatory effect on uterine epithelium. The present data show the potent effect of EM-800 preventing bone loss and lower serum cholesterol levels without the negative effect on the endometrium, thus suggesting the particular interest of this new fully tissue-specific selective estrogen receptor modulator.

Administration, Oral↗

Estrogen receptor alpha mediated induction of the transforming growth factor alpha gene by estradiol and 4-hydroxytamoxifen in MDA-MB-231 breast cancer cells.

The selective estrogen receptor modulator, 4-hydroxytamoxifen (4-OHT) is a full agonist at the transforming growth factor (TGF) alpha gene in ER negative breast cancer cells stably transfected with ER alpha cDNA (Levenson et al., Br. J. Cancer 77 (1998) 1812-1819). E(2) and 4-OHT increase TGF alpha mRNA and protein in a concentration dependent manner. The responses to E(2) and 4-OHT are blocked by the pure antiestrogen ICI 182,780, which does not induce TGF alpha. Transfected MDA-MB-231 cells contain functional ER alpha but no ER beta function was detected. Neo transfected cells that did not express ER alpha or cells stably transfected with the DNA binding domain mutant C202R/E203V which prevents gene activation did not induce TGF alpha mRNA after either E(2) or 4-OHT treatment. An examination of the time course for either 10 nM E(2) or 1 microM 4-OHT for MDA-MB-231 cells stably transfected with cDNA for ER alpha showed increases in TGF alpha mRNA within 2 or 3 h respectively. Cells pretreated with cycloheximide (1 microg/ml) showed induced TGF alpha mRNA in response to E(2) or 4-OHT but TGF alpha mRNA induction was blocked by actinomycin D (1 microg/ml). We conclude that both E(2) and 4-OHT induce TGF alpha by direct interaction of ER alpha with DNA and that ER beta is not involved in the estrogen-like response to 4-OHT in the MDA-MB-231 cells.

Blotting, Northern↗

Phytoestrogens for hormone replacement therapy?

Due to some severe side effects "classical" hormone replacement therapy (HRT) is currently being challenged by a therapy with phytoestrogens. Particularly soy and red clover derived isoflavones are advertised as selective estrogen receptor modulators (SERMs) with only desired and no undesired estrogenic effects. Evidence that this is the case however is scarce. Most studies investigating climacteric complaints did not find beneficial effects. A proposed beneficial effect on mammary cancer is unproven. The majority of studies however indicate an antiosteoporotic effect of isoflavones, while putative beneficial effects in the cardiovascular system are questionable due to the fact that estradiol which--like isoflavones--increase HDL and decrease LDL concentrations appear not to prevent arteriosclerosis in the human. In the urogenital tract, including the vagina, soy and red clover derived isoflavones are without effects. Cimicifuga racemosa extracts are traditionally used for the treatment of climacteric complaints. Evidence is now available that the yet unknown compounds in Cimicifuga racemosa extracts prevent climacteric complaints and may also have antiosteoporotic effects.

Bone and Bones↗

Potentiation of human estrogen receptor alpha-mediated gene expression by steroid receptor coactivator-1 (SRC-1) in Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae was used to reconstruct a human estrogen receptor alpha (ERalpha)-mediated transcription activation system. The level of reporter gene activation was dependent on both the position of the estrogen response element (ERE) relative to the translation start site and the number of EREs in the hybrid promoter. A G400V amino acid alteration in the ERalpha polypeptide decreased sensitivity to 17beta-estradiol (E(2)), demonstrating the hormone responsiveness of ERalpha to be qualitatively and quantitatively similar in yeast and mammalian cells. Coexpression of SRC-1a, a potent stimulator of ERalpha function in mammalian cells, potentiated ERalpha-mediated gene expression over fivefold in a E(2)-dependent manner. Deletion of 56 amino acids at the C-terminal end of SRC-1a resulted in a protein with enhanced ability to potentiate ERalpha-mediated gene expression, which mimics the activity of the same truncation in human SRC-1a as well as the SRC-1e isoform that has the 56 C-terminal residues replaced with a different 14 amino acid peptide. The selective estrogen receptor modulator tamoxifen acted as a weak agonist of ERalpha-mediated gene expression and this weak activity was potentiated by SRC-1. Tamoxifen had no effect on E(2)-induced gene activation in either the presence or absence of SRC-1. In contrast to previously reported yeast-based ERalpha-transactivation systems, the system reported here in which SRC-1 functions as a bona fide coactivator should permit a more thorough dissection of the factors involved in ERalpha-mediated transcriptional activation.

Estradiol↗

Estrogen receptor-alpha and Sp1 interact in the induction of the low density lipoprotein-receptor.

Both estrogen and selective estrogen receptor modulators (SERMs) such as tamoxifen and raloxifene have been demonstrated to lower plasma low density lipoprotein (LDL)-cholesterol concentrations by stimulation of LDL receptor gene expression. To determine the molecular mechanisms of estradiol- and tamoxifen-induced LDL receptor expression, we performed transient transfection experiments with luciferase reporter gene-constructs under transcriptional control of the human LDL receptor promoter. We demonstrate, that estradiol and tamoxifen stimulate LDL receptor gene expression in human HepG2 hepatoma cells only when estrogen receptor (ER)-alpha but not when ER-beta is cotransfected. Deletion mutants and point mutations of the LDL receptor promoter reveal that estradiol- and tamoxifen-stimulated expression of this gene depends on an intact repeat 3 in the LDL receptor promoter, a cis-element previously shown to interact with Sp1. Gel mobility analyses demonstrated estradiol- and tamoxifen-stimulated binding of nuclear proteins to repeat 3 (bp -56 to bp -36) of the LDL receptor promoter. These data provide an alternative mechanism of LDL receptor gene expression by non-classical estradiol- and tamoxifen-stimulated induction through an ER-alpha/Sp1 complex.

Cell Line, Tumor↗

Role of steroid sulfatase in local formation of estrogen in post-menopausal breast cancer patients.

More than two-thirds of breast cancers occur in post-menopausal women, and depend on the estrogens for their proliferation and survival. For the treatment of estrogen-dependent breast cancers, two major treatment options are now available. One is selective estrogen receptor modulator (SERM) such as Tamoxifen and another is aromatase inhibitor such as Anastrozole, Letrozole and Exemestane, which reduce local in situ formation of estrogens. Although these therapies are clinically active for advanced and early breast cancers, de novo and/or acquired resistance to SERM and/or aromatase inhibitors are also clinical problem. Recent studies suggest that local formation of estrogens in the breast tumors is more important than circulating estrogen in plasma for the growth and survival of estrogen-dependent breast cancer in post-menopausal women. The rationale for the importance of local formation of estrogens is based on the following evidences. Estradiol (E2) levels in breast tumors are equivalent to those of pre-menopausal patients, although plasma E2 levels are 50-fold lower after menopause. E2 concentrations in breast tumors of post-menopausal women are 10-40 times higher than serum level. Biosynthesis of estrogens in breast tumors tissues occurs via two major different routes, one is aromatase pathway and another is steroid-sulfatase (STS) pathway. Whereas many studies has been reported about aromatase inhibitor and its clinical trial results in breast cancer patients, limited information are available regarding to other estrogen regulating enzymes including STS, its role in breast tumors and STS inhibitors. STS is the enzyme that hydrolyses estrone 3-sulfate (E1S) and dehydroepiandrosterone-sulfate (DHEA-S) to their active un-sulfoconjugated forms, thereby stimulating the growth and survival of estrogen-dependent breast tumors. It has been well known that E1S level are much higher than E2 level both in plasma and tumor of post-menopausal patients. Recent reports show that more than 80% of breast tumors are stained with anti-STS antibody and the expression of STS is an independent prognostic factor in breast cancer. Taking these findings into consideration, local formation of estrogens could be partially synthesized from large amount of E1S by STS, which exist in breast cancer. On the other hand, aromatase localizes in stroma and adipocyte surrounding breast cancer. Furthermore, since estrogen formation from E1S and DHEA-S (STS pathway) cannot be blocked by aromatase inhibitors, STS is thought to be a new molecular target for the treatment of estrogen-dependent tumor post-SERM and/or aromatase inhibitors. In this symposium, these recent rationale for the importance of STS in post-menopausal breast cancer patients is reviewed as well as STS inhibitor.

Animals↗

An estrogen receptor basis for raloxifene action in bone.

Although controversy remains regarding direct effects of estrogen on bone, in vivo data clearly show that estrogens suppress bone turnover, resulting in decreased bone resorption and formation activity. Selective estrogen receptor modulators (SERMs), such as raloxifene, produce effects on bone which are very similar to those of estrogen. In vitro, both raloxifene and estrogen inhibit mammalian osteoclast differentiation and bone resorption activity, but only in the presence of IL-6. Data from a number of ovariectomized rat model manipulations (i.e. hypophysectomy, low calcium diet and drug combinations) demonstrate a strong parallel between the antiosteopenic effects of raloxifene and estrogen. A characteristic action of estrogens on the skeleton is inhibition of longitudinal bone growth, an effect which is not observed with other resorption inhibitors, including calcitonin and bisphosphonates. Consistent with an estrogen-like mechanism on bone, raloxifene inhibits longitudinal bone growth in growing rats. In addition to the overall similarity of the bone activity profile in animals, estrogen and raloxifene also produce similar effects on various signaling pathways relative to the antiosteopenic effect of these two agents. For example, IL-6, a cytokine involved in high turnover bone resorption following estrogen deficiency in rats, is suppressed by both raloxifene and estrogen. Raloxifene and estrogen also produce a similar activation of TGF-beta3 (a cytokine associated with inhibition of osteoclast differentiation and activity) in ovariectomized rats. Like 17beta-estradiol, raloxifene binds with high affinity to both estrogen receptor-alpha (ER alpha) and estrogen receptor-beta (ER beta). Crystal structure analyses have shown that 17beta-estradiol and raloxifene bind to ER alpha with small, but important, differences in three dimensional structure. These subtle differences in the conformation of the ligand:receptor complex are likely the basis for the key pharmacological differences between estrogens and the various SERMs (i.e. raloxifene vs tamoxifen). Raloxifene also produces estrogen-like effects on serum cholesterol metabolism and the vasculature. Thus, while raloxifene exhibits a complete estrogen antagonist in mammary tissue and the uterus, it produces beneficial effects on the cardiovascular system and prevents bone loss via an estrogen receptor mediated mechanism.

Animals↗

Synthesis and biological activity of trans-2,3-dihydroraloxifene.

The synthesis and biological evaluation of trans-2,3-dihydroraloxifene, 2, is described. The synthesis proceeds in 8 steps in 20% overall yield. Relative trans 2,3-stereochemistry is definitively established in ester 6, which is converted to the title compound via derivatization, Grignard addition, and deprotection. Evaluation in vitro shows the compound to be a potent selective estrogen receptor modulator (SERM).

Binding, Competitive↗

New findings about endocrine therapy for breast cancer.

For over a decade, the selective estrogen receptor modulator, tamoxifen, has been the primary agent for adjuvant endocrine therapy for steroid receptor-positive breast cancer. New data over the last 2 years now suggest that its primacy may be challenged by strategies that lower circulating and/or intratumoral estrogens. Recent trials support the use of ovarian suppression approaches with or without tamoxifen in place of chemotherapy in premenopausal women. A large randomized trial has also established the short-term efficacy and safety of the aromatase inhibitor, anastrozole, in postmenopausal women. How and when to integrate these new approaches into standard practice are topics of debate. Ongoing research is focused on choice of endocrine approach, duration and sequencing of endocrine treatment, identification of better predictive markers for hormone response, and assessment of long-term risks and benefits.

Anastrozole↗

Challenges in the endocrine management of breast cancer.

The goal of endocrine therapy in breast cancer is to block the action of estrogen on the tumor cells either by inhibiting estrogen from binding to the specific estrogen receptor or by inhibiting its synthesis. Tamoxifen, a selective estrogen receptor modulator, is the standard endocrine treatment for hormone receptor-positive breast cancer, both in the adjuvant and metastatic settings. Tamoxifen inhibits the binding of estrogen to the receptor, resulting in inhibition of hormone action. However, as tamoxifen is also weakly estrogenic, it may not be optimally effective and increases the risk of endometrial cancer and stroke. Furthermore, patients may be refractory or may become resistant to tamoxifen treatment. Since aromatase inhibitors (AI) block the synthesis of estrogen and have no intrinsic estrogenic activity, they have the potential to be more effective than tamoxifen. Their different mechanism of action and chemical structures may also circumvent tamoxifen resistance. Consequently, AIs are currently being evaluated as an alternative to tamoxifen treatment. A preclinical model has recently been developed to compare the efficacy of AIs and antiestrogens in different treatment schemes and to assist in the design of clinical trials. Current studies with the MCF-7Ca xenograft model are exploring the effects of combination and sequential therapy on tumor growth. The efficacy of AIs in the treatment of hormone receptor-positive breast cancer was first demonstrated in five multicenter second-line trials enrolling several hundreds of postmenopausal patients with metastatic breast cancer who had failed tamoxifen treatment. More recently, anastrozole demonstrated efficacy at least equivalent to that of tamoxifen in first-line randomized, phase III clinical trials in postmenopausal women with hormone receptor-positive or unknown metastatic breast cancer, whereas letrozole demonstrated superiority. The steroidal AI exemestane is currently under evaluation. Letrozole is the only AI to have been studied in a randomized, phase III trial in the neoadjuvant setting. In this trial, more patients underwent breast-conserving surgery with letrozole than with tamoxifen. Smaller phase II studies also suggest that both anastrozole and exemestane are active in the neoadjuvant setting. Because neoadjuvant trials permit temporal sampling of breast tissue, substudies in the phase III trial with letrozole have examined the impact of such biomarkers as estrogen receptor, progesterone receptor and epidermal growth factor receptor family members, HER-1 and HER-2, on patient response. AIs are currently under evaluation in the adjuvant setting, and preliminary results of the Arimidex, Tamoxifen Alone or in Combination (ATAC) trial have been reported. AIs have proven as safe as tamoxifen in trials in patients with metastatic breast cancer. Ongoing clinical trials in the adjuvant setting include companion studies of end-organ effects, particularly bone metabolism and lipid metabolism evaluations. Quality-of-life assessments are also parts of major clinical trials. A head-to-head quality-of-life assessment of anastrozole compared with letrozole demonstrated patient preference for letrozole. These assessments also clearly indicated the eagerness of patients to participate actively in treatment decisions

Adult↗

SERM Drugs for the Prevention of Osteoporosis.

Although estrogens have proved useful in the prevention and treatment of osteoporosis, their side effects (for example, those on breast and endometrial cancer) are worrying to patients and physicians alike. Therefore, selective estrogen receptor modulator (SERM) drugs have been developed for use in their stead. The triphenylethylene drug tamoxifen proved to be protective against bone loss, but had side effects on uterus similar to those of natural estrogens. The tamoxifen derivative toremifene has less effect on bone. Further derivatives of tamoxifen (droloxifene, idoxifene) can be expected to act like tamoxifen when approved for clinical testing. The non-steroidal benzothiophene derivative, raloxifene, is the best SERM available thus far. It does not increase the incidence of endo-metrial cancer; in addition, like tamoxifen, it has the potential to prevent breast cancer, but has a better profile in its actions on bone (for example, it reduces the vertebral fracture rate more effectively than tamoxifen). Unlike estrogen, it decreases blood triglicerides as well as cholesterol.

Journal Article↗

Targeted Antiestrogens to Prevent Breast Cancer.

Tamoxifen, the first selective estrogen receptor modulator (SERM), has provided invaluable laboratory and clinical evidence that such drugs can reduce the risk of breast cancer and increase bone density. Raloxifene is available for the prevention of osteoporosis, and preliminary studies show a decrease in breast cancer risk. On the basis of current information about the pharmacology of SERMs, a large breast cancer prevention trial called study of tamoxifen and raloxifene (STAR) has started in the USA. Results should be available in the next seven years.

Journal Article↗

The prognostic value and clinical utility of estrogen and progesterone receptors in endometrial carcinoma.

In the United States, endometrial carcinoma is the most common gynecologic malignancy, and accounts for 4,900 deaths per year in the United States. While this disease has relatively good cure rates, there is motivation to describe other determinants, which may help in the treatment of this disease. Attempts have been made to correlate hormone receptor status with disease-free intervals and survival in patients with endometrial carcinoma. The weight of evidence seems to support that of the two hormone receptors, progesterone is the more significant predictor of patient outcome. If hormone receptors are to be used in the management of endometrial carcinoma, they should be determined by immunohistochemistry. In the adjuvant setting, patients with progesterone positive tumors are more amenable to treatment with progestational agents than are patients with receptor negative tumors. Future areas of research include the use of tamoxifen and selective estrogen receptor modulators in the chemoprevention and treatment of endometrial carcinoma.

Journal Article↗

Inherited coagulopathies in OB/GYN.

There is an increased risk of venous thrombosis in women with inherited plasma protein coagulopathies (thrombophilias). Although a general screening for thrombophilia is impractical, risk assessment based on identification of other hypercoagulable states-such as a personal or family history of venous thrombosis-can identify patients who may benefit from testing. Those patients testing positive for thrombophilia need to be counseled regarding the implications of oral contraceptive use, hormone replacement therapy, use of selective estrogen receptor modulators, and pregnancy.

Journal Article↗