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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↗
PubMed2000

Future possibilities in the prevention of breast cancer: role of genetic variation in breast cancer prevention.

Risk factors for breast cancer are related to endogenous hormones and reproductive events. As such, traditional cancer prevention strategies are not easily applicable. Tamoxifen and other selective estrogen receptor modulators (SERMs) offer a new preventive strategy for some high-risk women, but have not yet been shown to be efficacious for all women. New tools to identify high-risk women are needed. One such tool is the development of a multigenic model of breast cancer susceptibility that can be used to screen women in order to identify those who carry a combination of alleles that puts them at significantly increased risk.

Adult↗
PubMed2006

Effects of raloxifene on caveolin-1 mRNA and protein expressions in vascular smooth muscle cells.

Caveolin-1 is regulated by estrogen in vascular smooth muscle cells. Raloxifene, a selective estrogen receptor modulator that possibly has cardioprotective properties without an increased risk of cancer or other side effects of estrogen, may be used in women with risk of coronary artery disease. However, the relationship between raloxifene and caveolin-1 is still unknown. Therefore, this study was designed to see whether raloxifene regulates caveolin-1 expression and if so, whether such regulation is mediated by estrogen receptor. Rat aortic smooth muscle cells were cultured in the absence or presence of raloxifene (10(8-) to 10(6-) M) for 12 or 24 h. Both mRNA and protein levels of caveolin-1 were increased significantly after 24 h treatment with raloxifene. These increases were inhibited by estrogen receptor antagonist ICI 182780 (10(5-) M). Results of this study suggest that raloxifene stimulates caveolin-1 transcription and translation through estrogen receptor mediated mechanisms.

Animals↗
PubMed2002

Molecular determinants for the tissue specificity of SERMs.

Selective estrogen receptor modulators (SERMs) mimic estrogen action in certain tissues while opposing it in others. The therapeutic effectiveness of SERMs such as tamoxifen and raloxifene in breast cancer depends on their antiestrogenic activity. In the uterus, however, tamoxifen is estrogenic. Here, we show that both tamoxifen and raloxifene induce the recruitment of corepressors to target gene promoters in mammary cells. In endometrial cells, tamoxifen, but not raloxifene, acts like estrogen by stimulating the recruitment of coactivators to a subset of genes. The estrogen-like activity of tamoxifen in the uterus requires a high level of steroid receptor coactivator 1 (SRC-1) expression. Thus cell type- and promoter-specific differences in coregulator recruitment determine the cellular response to SERMs.

Breast↗
PubMed2001

Use of SERMs for the adjuvant therapy of early-stage breast cancer.

Tamoxifen was the first in a class of drugs now commonly referred to as selective estrogen receptor modulators or SERMs. SERMs exhibit tissue-specific estrogenic agonist/antagonist activity through their ability to bind to the estrogen receptor alpha (ER) protein and interact with coregulatory proteins, thereby modulating transcription of estrogen target genes. Since its first approval by the United States Food and Drug Administration (FDA) in 1977, tamoxifen has been found to (a) lower the risk of recurrence and death for women with early-stage hormone receptor-positive breast cancer, irrespective of menopausal and node status or use of adjuvant chemotherapy; (b) reduce the risk of invasive breast cancer following breast conservation in women with ductal carcinoma in situ (DCIS); and (c) reduce the risk of breast cancer in high-risk women. Toremifene is the only other SERM approved by the FDA for breast cancer treatment. However, it offers no clear clinical advantage over tamoxifen in the adjuvant or metastatic settings. Several other SERMs are in various phases of clinical development. In addition, strategies to combine SERMs with other endocrine therapy like ovarian suppression or aromatase inhibitors are active areas of investigations. At present, SERMs are recognized as the first targeted and relatively nontoxic medical therapy for women with high-risk or steroid hormone receptor-positive breast cancer.

Breast Neoplasms↗
PubMed2002

Raloxifene is associated with less side effects than tamoxifen in women with early breast cancer: a questionnaire study from one physician's practice.

OBJECTIVE: Selective estrogen receptor modulators (SERMs) are being used increasingly for the prevention and treatment of breast cancer. The currently available SERMs, tamoxifen and raloxifene, are both associated with antiestrogenic side effects that can be bothersome. However, no data exist on how they compare in this regard. We conducted a retrospective, questionnaire-based study to answer this question. METHODS: Women with early breast cancer in one physician's practice who had received either or both of these drugs were surveyed using a self-administered questionnaire. Respondents graded the frequency and severity of side effects related to estrogen deprivation, such as vaginal dryness, mood changes, hot flashes, weight gain, and changes in libido, as well as other side effects, such as vaginal discharge. They were separated into three groups for analysis (group 1, tamoxifen only; group 2, raloxifene only; group 3, both drugs). Side effects graded 4 or 5 (or weight gain >10 pounds) were considered severe. RESULTS: Two hundred sixty-four questionnaires were available for analysis. Women on raloxifene had a shorter average duration of therapy. In comparing the tamoxifen and raloxifene groups, vaginal discharge, severe hot flashes, and weight gain of >10 pounds were significantly more frequent with tamoxifen. However, weight gain was also related to the duration of therapy with either drug. CONCLUSIONS: In this observational study, antiestrogenic side effects were common with either tamoxifen or raloxifene. Raloxifene is associated with significantly less vaginal discharge and severe hot flashes than tamoxifen in women with early breast cancer. Although weight gain of >10 pounds may also occur less frequently on this drug, this may be confounded by the shorter average duration of raloxifene therapy.

Adult↗
PubMed2005

(+)-Z-Bisdehydrodoisynolic acid ameliorates obesity and the metabolic syndrome in female ZDF rats.

OBJECTIVE: The putative selective estrogen receptor modulator (+)-Z-bisdehydrodoisynolic acid (Z-BDDA) has been found to improve cardiovascular risk in rodents. The objective of this study was to investigate the effectiveness of (+)-Z-BDDA compared with the antidiabetic drug, rosiglitazone, in treating obesity and risk factors associated with the metabolic syndrome. RESEARCH METHODS AND PROCEDURES: Female Zucker Diabetic Fatty rats were randomly assigned to three treatment groups for 29 weeks: control (C), 1.8 mg (+)-Z-BDDA/kg diet [control diet + (+)-Z-BDDA (CB)], or 100 mg rosiglitazone/kg diet [control diet + rosiglitazone (CR)]. At sacrifice, physiological, biochemical, and molecular parameters were examined. RESULTS: CB animals gained less weight and exhibited a decrease in total body lipids (p < 0.05) as compared with C or CR rats. Body weight and total body lipids were the highest in CR rats (p < 0.05). Liver weights in CB and CR rats were lower (p < 0.05) than in C rats, whereas kidney weights were lower in CB (p < 0.05) than in C and CR animals. Fasting plasma glucose was lower (p < 0.05) in the CB and CR animals when compared with C animals. C rats exhibited the highest concentration of total plasma cholesterol, and CR-treated rats exhibited the lowest concentration. Plasma triglycerides followed the same pattern as plasma cholesterol. Histomorphometry of heart vasculature revealed that CB and CR treatments produced a significant shift from small to large venules and arterioles compared with C (p < 0.05). Liver expression profiles of peroxisome proliferator-activated receptor (PPAR) alpha, PPARgamma, and PPAR-regulated genes revealed encouraging CB-induced effects. DISCUSSION: These results suggest that (+)-Z-BDDA may have applications in treating obesity and complications associated with the metabolic syndrome.

Animals↗
PubMedDate not supplied

Effects of ospemifene, a novel SERM, on hormones, genital tract, climacteric symptoms, and quality of life in postmenopausal women: a double-blind, randomized trial.

OBJECTIVE: Ospemifene, a novel selective estrogen receptor modulator, shows a potential for prevention and treatment of osteoporosis in postmenopausal women. We studied the effects of ospemifene on hormone levels, genital tract organs, climacteric symptoms, and quality of life. DESIGN: A double-blinded study in which 160 postmenopausal women were randomly allocated to receive either ospemifene at three different daily doses (30, 60, or 90 mg) or placebo for 3 months. RESULTS: No significant differences were observed among the study groups in clinical characteristics or parameters reflecting estrogen action at baseline. Ospemifene reduced follicle-stimulating hormone and insulin-like growth factor I levels, whereas estradiol failed to change at all, and luteinizing hormone was reduced only in the 90-mg group of ospemifene. In the vast majority of participants, the endometrium remained atrophic after 3 months of treatment with ospemifene. Although the rate of proliferative endometrium slightly increased in all groups, including placebo, no hyperplasia or bleeding occurred in any participant. Ospemifene had no effect on the appearance of proliferation marker Ki-67 in the endometrium as compared with placebo, and endometrial thickness increased by mean 0.4 to 0.6 mm (P < 0.01, P < 0.05 and P < 0.05 for 30, 60 and 90 mg ospemifene, respectively). Uterine volume slightly increased (8.4%-14.7%) in the ospemifene groups (P > 0.05), perhaps as a result of increased uterine blood flow. The most conspicuous finding was the significant estrogenic effect on vaginal epithelium, as evidenced by an increase in intermediate and superficial cells in repeat Pap smears. Ospemifene was not observed to aggravate climacteric symptoms or cause adverse events, nor did it suppress climacteric symptoms. CONCLUSIONS: Ospemifene at daily doses of 30 to 90 mg did not stimulate endometrium or aggravate hot flashes but clearly had a rather strong estrogenic effect on the vaginal epithelium during a 3-month treatment period. Such effects would be advantageous if ospemifene were found to be effective in the long-term prevention of osteoporosis.

Aged↗
PubMed2000

Effects of the estrogen antagonist EM-652.HCl on energy balance and lipid metabolism in ovariectomized rats.

OBJECTIVE: The estrogen antagonist EM-652.HCl behaves as a highly potent and pure antiestrogen in human breast and uterine cancer cells. Because of its pure antiestrogenic activity in these cells, and because its prodrug, EM-800, reduces bone loss and decreases serum cholesterol and triglycerides in the rat, EM-652.HCl can be classified as a pure selective estrogen receptor modulator (SERM). This study was conducted to assess the ability of EM-652.HCl to prevent obesity and abnormalities of lipid metabolism induced by ovariectomy in a rat model. DESIGN: Female rats were left intact or ovariectomized (OVX), and OVX rats were treated with placebo, estradiol (E2), or EM-652.HCl for 20 days. At the end of the treatment period, parameters of energy balance and determinants of lipid metabolism were assessed. RESULTS: As expected, OVX increased energy intake, which in turn was accompanied by an increased energy, fat and protein gain and higher food efficiency. OVX also increased the triglyceride content of the liver and produced hypercholesterolemia and hyperinsulinemia. The weight of representative white adipose depots was higher in OVX than in intact rats. Lipoprotein lipase activity was higher in white adipose tissues of OVX rats than in those of intact animals, whereas its activity was lower in oxidative tissues (brown adipose and soleus muscle). Replacement therapy with a physiological dose of E2 prevented most of the abnormalities in energy and lipid metabolism brought about by OVX, although its orexigenic effect was only partially corrected. In contrast, treatment of OVX rats with EM-652. HCl completely abolished OVX-induced obesity and its related abnormalities in lipid metabolism and glucose/insulin homeostasis. CONCLUSION: These findings demonstrate that EM-652.HCl can be considered as an effective agent to prevent OVX-induced obesity. The present study also shows that EM-652.HCl reduces cardiovascular risk factors associated with obesity such as hyperlipidemia and insulin resistance.

Animals↗
PubMed2004

Mechanisms for altered reproductive function in female rats following neonatal administration of raloxifene.

OBJECTIVE: Raloxifene is a non-steroidal selective estrogen receptor modulator (SERM) that mimics estrogenic activity on bone density and blood lipid concentration without uterotropic actions. Previous data from our laboratory indicated that, as is the case for estrogen, neonatal administration of raloxifene disturbed normal differentiation of the hypothalamic circuitries governing the gonadotropic axis. In contrast, raloxifene did not act in the same way as estrogen does on the neuronal systems controlling sexual receptivity in the female rat. At present, however, the mechanisms for these organizing effects of raloxifene are not completely elucidated. DESIGN AND METHODS: To analyze this phenomenon, female rats were injected daily with raloxifene (50, 100, 250 or 500 microg/rat per day) between days 1 and 5 of age. On day 23, hypothalamic gonadotropin-releasing hormone (LHRH) mRNA expression was assessed, and pituitary and plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were measured in basal and LHRH-stimulated conditions. In addition, LH and FSH responses to ovariectomy were evaluated in raloxifene-treated females. Finally, we monitored the ability of neonatal administration of a potent LHRH agonist ([d-Ala(6),d-Gly(10)]-LHRH ethylamide; 0.01 microg/kg per 12 h on days 1-5) to counteract the effects of raloxifene. RESULTS: Our analyses demonstrated that prepubertal rats (23-day-old females) treated neonatally with raloxifene showed decreased hypothalamic LHRH mRNA expression levels, reduced pituitary content of LH and FSH, reduced basal and LHRH-stimulated LH secretion in vivo and in vitro, and decreased response to ovariectomy. In addition, adult females treated neonatally with raloxifene showed anovulation and reduced serum LH levels; these effects were not prevented by the simultaneous administration of a LHRH agonist. CONCLUSION: In conclusion, our data demonstrate that neonatal administration of raloxifene can disrupt the programming of hypothalamic-pituitary-ovarian axis function. Reduced LH secretion, under basal and LHRH-stimulated conditions and after ovariectomy, is probably related to decreased LHRH expression, reduced pituitary LH content and/or decreased pituitary responsiveness to hypothalamic LHRH.

Animals↗
PubMedDate not supplied

Similarity of uterine mucosa changes in patients treated by raloxifen and tamoxifen.

BACKGROUND: Selective estrogen receptor modulators (SERMS) like Tamoxifen and Raloxifen are used for menopausal symptoms, prevention of cardio-vascular diseases, osteoporosis and mammary carcinoma. Tamoxifen acts as an estrogen inhibitor on the mammary gland, but stimulates postmenopausal uterine mucosa in about 25% of cases while decreasing the risk of osteoporosis. MATERIALS, METHODS AND RESULTS: In three menopausal women, 56, 79 and 62 years of age, we found uterine mucosal changes similar to what is found in Tamoxifen-treated patients. Using light microscopy and immuno-histopathological techniques, partly cystic mucosa with both atrophic and proliferating glands was found. Strong stromal proliferation was also seen with the typical sharp-edged form of stromal cells and mitoses. A strong ostrogen and progesterone reaction was revealed with immuno-histopathological techniques in both gland and stromal parts. CONCLUSION: Taking into account the variable amount of different estrogen-receptor types in the uterine mucosa, we can not in the long run expect that no patient will react with estrogen-stimulation features on SERMs like Raloxifen. Further studies and thorough observations are needed to elucidate the true frequency of Raloxifen impact on the uterine mucosa.

Aged↗
PubMed2005

Raloxifene and cardiovascular health: its relationship to lipid and glucose metabolism, hemostatic and inflammation factors and cardiovascular function in postmenopausal women.

CHD is one of the most common serious chronic conditions in postmenopausal women and leads to extremely high risk for recurrent myocardial infarction and death. On the basis of the currently available randomized clinical-trial results the role of conventional HRT for treatment and prevention of CHD is rapidly evolving from presumed benefit to proven harm, at least in some categories of women yet to define. For this reason there has been a particular interest in potential clinical uses of selective estrogen receptor modulators (SERMs). SERMs are a class of compounds that can act as estrogen receptor (ER) agonists in some domains (bone and lipids) and acting as ER antagonists in others (breast and uterus). Raloxifene hydrochloride is an antiestrogen that is currently approved only to treat osteoporosis in postmenopausal women. Because of its effects on lipids and other biomarkers of cardiovascular risk, there is great interest in determining whether it may benefit the cardiovascular system. The great majority of data on cardiovascular effects of raloxifene concern effects on lipids and markers of thrombosis and inflammation. The purpose of this review is to summarize the best available evidence concerning raloxifene and cardiovascular disease focusing some areas known to be important risk factors for cardiovascular diseases: lipids and lipoproteins, glucose metabolism, hemostatic factors, markers of inflammation and cardiovascular function.

Aged↗
PubMed2002

Bone histomorphometric and biochemical marker results of a 2-year placebo-controlled trial of raloxifene in postmenopausal women.

Raloxifene is a selective estrogen receptor modulator that has been shown to increase bone density. The purpose of this study was to examine the effects of raloxifene on bone tissue by studying bone biopsy specimens before and after 2 years of raloxifene or placebo therapy. The women in this study were participants of the double-blind, placebo-controlled, multicenter study, the Multiple Outcomes of Raloxifene Evaluation (MORE) trial. Subjects from two U.S. sites and two European sites were included if they consented to a bone biopsy. Iliac crest bone biopsies were performed at baseline and after 2 years. Tetracycline labeling preceded each biopsy. A total of 65 paired biopsy specimens were evaluated with 25, 22, and 18 patients in the placebo, raloxifene HCl (60 mg) and raloxifene HCl (120 mg) treatment groups, respectively. They were analyzed using standard histomorphometry. None of the biopsy specimens showed evidence of toxic effects on bone or bone cells or met criteria for osteomalacia. Biopsy specimens in the placebo and raloxifene groups had the appearance of normal bone, with no evidence of marrow fibrosis or increases in the amount of woven bone or numbers of empty osteocyte lacunae. Compared with the baseline, the bone formation rate (BFR) decreased significantly in both raloxifene groups. The change in BFR in the group treated with 120 mg of raloxifene was -62.3%, which was significantly lower than the change in the placebo group of -21.0% (p = 0.03). No change in resorption parameters could be measured by histomorphometry, but there was a decrease in urinary type I collagen excretion. The results from this study suggest that raloxifene has actions on bone tissue that are similar to those observed with estrogen. The depressive effects on bone remodeling are less marked than the effects seen with alendronate.

Aged↗
PubMed2003

Rapid signaling of estrogen in hypothalamic neurons involves a novel G-protein-coupled estrogen receptor that activates protein kinase C.

Classically, 17beta-estradiol (E2) is thought to control homeostatic functions such as reproduction, stress responses, feeding, sleep cycles, temperature regulation, and motivated behaviors through transcriptional events. Although it is increasingly evident that E2 can also rapidly activate kinase pathways to have multiple downstream actions in CNS neurons, the receptor(s) and the signal transduction pathways involved have not been identified. We discovered that E2 can alter mu-opioid and GABA neurotransmission rapidly through nontranscriptional events in hypothalamic GABA, proopiomelanocortin (POMC), and dopamine neurons. Therefore, we examined the effects of E2 in these neurons using whole-cell recording techniques in ovariectomized female guinea pigs. E2 reduced rapidly the potency of the GABAB receptor agonist baclofen to activate G-protein-coupled, inwardly rectifying K+ channels in hypothalamic neurons. These effects were mimicked by the membrane impermeant E2-BSA and selective estrogen receptor modulators, including a new diphenylacrylamide compound, STX, that does not bind to intracellular estrogen receptors alpha or beta, suggesting that E2 acts through a unique membrane receptor. We characterized the coupling of this estrogen receptor to a Galpha(q)-mediated activation of phospholipase C, leading to the upregulation of protein kinase Cdelta and protein kinase A activity in these neurons. Moreover, using single-cell reverse transcription-PCR, we identified the critical transcripts, PKCdelta and its downstream target adenylyl cyclase VII, for rapid, novel signaling of E2 in GABA, POMC, and dopamine neurons. Therefore, this unique Gq-coupled estrogen receptor may be involved in rapid signaling in hypothalamic neurons that are critical for normal homeostatic functions.

Animals↗
PubMed2001

Randomized control study of the effects of raloxifene on serum lipids and homocysteine in older women.

OBJECTIVE(S): Raloxifene, a selective estrogen receptor modulator, has beneficial estrogen agonist effects on bone and cardiovascular risk factors and estrogen antagonist effects on the breast and uterus. Limited clinical data have shown a sustained decrease in total cholesterol, low-density lipoprotein cholesterol, and homocysteine levels; an elevated homocysteine level is an independent risk factor for atherosclerosis. All of these studies were conducted in relatively young populations of women (mean age, 52-54 years). Raloxifene does not affect hot flushes, a major immediate symptom of menopause. This drug may therefore be useful in older women to prevent osteoporosis and cardiovascular disease. The aim of this clinical study was to evaluate the effects of raloxifene on plasma lipids and homocysteine in older women. STUDY DESIGN: The subjects were 45 healthy postmenopausal women, aged 60 to 70 years. The women were randomly assigned to therapy with raloxifene or placebo, 60 mg/d for 1 year. Twenty-six women received raloxifene and 19 received placebo. Checkups were performed every 3 months. At baseline and after 3, 6, 9, and 12 months of treatment we measured homocysteine, total serum cholesterol, triglycerides, and both high-density lipoprotein and low-density lipoprotein cholesterol. RESULTS: An effect on lipids was evident by 3 months with no significant additional modification at 12 months. Mean low-density lipoprotein cholesterol levels were lowered by 15% and total cholesterol was lowered by 8.5%. No reduction in high-density lipoprotein cholesterol or triglycerides was observed. After 3 months of therapy, homocysteine was significantly lower than at baseline (9.9 +/- 1.6 vs 11 +/- 2.1 micromol/L; P < .05). The greatest reduction with respect to baseline was reached after 6 months of therapy (-19.5% +/- 3%; P < .05). CONCLUSION(S): The results of our study show that raloxifene at a dose of 60 mg/d reduces serum concentrations of low-density lipoprotein cholesterol and total cholesterol in healthy older women. Our study shows that in older women raloxifene leads to a 19.5% +/- 3% reduction in fasting homocysteine levels. Raloxifene may have a favorable effect on the incidence of cardiovascular disease in older women.

Aged↗
PubMed2006

Effect of ormeloxifene on ovariectomy-induced bone resorption, osteoclast differentiation and apoptosis and TGF beta-3 expression.

Effect of ormeloxifene, a multifunctional selective estrogen receptor modulator, on prevention of ovariectomy-induced bone resorption in retired breeder female rats, osteoclastogenesis using bone marrow cells from adult Balb/c mice cultured in presence of M-CSF and RANKL, osteoclast apoptosis using terminal deoxynucleotidyl transferase fragment end labeling and TGF beta-3 expression were investigated. Raloxifene, a benzothiophene reported to mimic effects of estrogen in bone, and estradiol were used for comparison. Ormeloxifene (10(-6) and 10(-8)M) significantly inhibited osteoclastogenesis (P<0.001 versus vehicle control) as evidenced by lower number of TRAP-positive osteoclasts in bone marrow cultures and caused apoptosis of osteoclasts. The effect was almost equivalent to that observed in presence of estradiol-17 beta, except that significant number of cells undergoing apoptosis was evident even at 10(-9)M concentration of estradiol-17 beta (P<0.001). Raloxifene, though inhibited osteoclastogenesis at much lower concentrations (10(-8) to 10(-12)M; P<0.001), failed to cause apoptosis of osteoclasts at any of the concentrations used. While ormeloxifene, raloxifene and ethynylestradiol significantly prevented ovariectomy-induced bone loss in vivo in retired breeder female rats, prevention of ovariectomy-induced decrease in BMD and trabecular network of proximal tibia, calcium and phosphorus levels in femur and tibia and prevention of ovariectomy-induced down-regulation of TGF beta-3 expression in lumbar vertebrae was of lower order in raloxifene- than ormeloxifene- or ethynylestradiol-supplemented females. Both the SERMs, however, produced considerable estrogenic effects at the uterine level as evidenced by increase in weight, total and endometrial area and luminal epithelial cell height; the effect being generally greater in raloxifene- than ormeloxifene-treated rats. Findings demonstrate that inhibition of estrogen-deficiency osteoporosis by ormeloxifene, as in case of estradiol, was mediated via inhibition of osteoclastogenesis, apoptosis of osteoclasts and up-regulation of TGF beta-3 expression. Raloxifene, though effective in inhibiting osteoclastogenesis in vitro at much lower concentrations, was not only less potent in preventing ovariectomy-induced bone loss in retired breeder female rats in vivo but also appeared to have a different mechanism of action than ormeloxifene and estradiol.

Animals↗
PubMed2001

Induction of the progesterone receptor gene in estrogen target cells monitored by branched DNA signal amplification.

Estrogens have multiple effects on the growth and development of cells in their target tissues, including the uterus, ovary, breast, bone marrow and brain. The hormone regulates the transcription of diverse genes in these tissues via the estrogen receptor, a nuclear transcription factor. Naturally occurring estrogens and estrogen analogs including selective estrogen receptor modulators (SERMs), constitute important therapies for breast cancer and osteoporosis, and are major components of oral contraceptives. The in vitro biologic activities of pharmaceutical estrogen agonists and antagonists have frequently been monitored by cotransfection assay, where exogenous estrogen receptor and reporter genes are transiently inserted into a heterologous, non receptor-containing cell line, such as those derived from kidney cells. Here we describe an alternative to this method, where induction of an endogenous estrogen-responsive gene, the progesterone receptor gene, is monitored by branched DNA signal amplification. Assays are performed with cultured cells derived from estrogen-responsive tissues; namely, breast, uterine endothelium and bone. Hormonal induction occurs via the endogenous estrogen receptor of these cells. Our data show that SERMs, which are estrogen agonists on bone in vivo, antagonize estrogen-dependent target gene induction in conditionally immortalized osteoblast-like cells.

Alkaline Phosphatase↗
PubMed2001

In vitro and in vivo biologic effects of Ospemifene (FC-1271a) in breast cancer.

Ospemifene (FC-1271a) is a novel selective estrogen receptor modulator under development for osteoporosis prevention. In the present paper, we examine both the in vitro and in vivo effects of FC-1271a in breast cancer models. In vitro, the growth inhibitory effects of FC-1271a and its main metabolite are investigated in MCF-7 and MDA-MB-231 human breast cancer cells at doses ranging from 0.1 to 10 microM. Modulation of pS2 expression, an indicator of estrogen activity, was also examined in all experiments using reverse transcription-polymerase chain reaction. In vivo, the effects of treatment with 10, 25, 50, or 100 mg/kg FC-1271a on MCF-7 and MDA-MB-231 human tumor xenografts in athymic, ovariectomized mice were determined. For MCF-7 cells, FC-1271a and its main metabolite, toremifene VI (TOR VI) displayed anti-estrogenic effects in vitro as shown through growth inhibition and decreased expression of pS2. Treatment with FC-1271a in vivo inhibited MCF-7 tumor growth, compared with control (P< or =0.05). FC-1271a and TOR VI did not inhibit the growth of MDA-MB-231 cells in vitro, and no clear effects of FC-1271a treatment were seen on MDA-MB-231 tumor growth in vivo. In conclusion, FC-1271a appears to exert anti-estrogenic effects dependent on estrogen receptor positivity in vitro and in vivo on the growth of MCF-7 cells.

Animals↗