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The role of hormone replacement therapy in women with a previous diagnosis of breast cancer and a review of possible alternatives.

Estrogen replacement therapy either with (HRT) or without (ERT) accompanying progesterone is routinely offered to well women at the time of menopause, in order to relieve vasomotor symptoms, (hot flashes), reduce urogenital atrophy and reduce the risks of cardiovascular disease, osteoporosis and perhaps colon cancer and Alzheimer's disease. It is generally felt however, that women with a previous diagnosis of breast cancer are not suitable candidates for such therapy since either estrogen or progesterone may be associated with an increased risk of cancer recurrence. There are however, a variety of approaches to menopausal therapy in such women. A careful history must first be taken in order to identify the symptoms or conditions of concern. Vasomotor symptoms can be reduced by the use of other medications such as the antidepressant venlafaxine (Effexor). Estring, a vaginal estrogen ring can be used to reduce genitourinary symptoms, with little systemic estrogen absorption. Osteoporosis can be prevented or treated with calcium supplements, exercise, improved diet, bisphosphonates and/or selective estrogen receptor modulators (SERMs) while cardiovascular risk can be reduced by diet and exercise, as well as the appropriate use of lipid lowering and antihypertensive medications.

Alzheimer Disease↗

Stimulation of DNA synthesis and c-fos mRNA expression in primary rat hepatocytes by estrogens.

The mechanism(s) of tumour promotion in liver by estrogens is not well understood although growth stimulation is known to be one important element of their action. As a basis for studying mechanisms of growth control by estrogens, effects of both natural and synthetic estrogens on DNA synthesis and protooncogene c-fos mRNA expression were examined in primary cultures of normal rat hepatocytes. 17beta-Estradiol (E(2)) alone was stimulatory and exhibited dramatic synergism with epidermal growth factor (EGF) in stimulating DNA synthesis. All estrogens tested (natural, synthetic, steroidal and non-steroidal) exhibited an ability to stimulate hepatocyte DNA synthesis. This appears to correlate with their ability to induce c-fos mRNA expression. In contrast to a non-estrogenic liver tumour promoter, phenobarbital, insulin is not permissive for the growth-stimulatory action of E(2). Dexamethasone, which is required for stimulation of DNA synthesis by the non-estrogenic tumour promoter alpha-hexachlorocyclohexane and tetradecanoylphorbol acetate, completely blocked E(2)-stimulated DNA synthesis. Such differential requirements for auxiliary factors suggests that estrogen and other non-estrogenic liver tumour promoters act via distinct mechanisms in stimulating hepatocyte DNA synthesis. E(2) alone had no effect, but when in combination with EGF significantly induced c-fos mRNA expression at early times in culture (maximal at 10 h in culture). Such findings, coupled with the observations that (i) E(2) and EGF were synergistic in growth stimulation, (ii) estrogen receptor levels are higher at early times in culture and (iii) the growth-stimulatory ability of E(2) is limited to 4-24 h in culture, support the notion that in hepatocytes E(2) acts via the estrogen receptor to transactivate c-fos expression (an interaction with EGF), which ultimately culminates in enhanced DNA synthesis. Dexamethasone did not block E(2)-induced c-fos gene expression, suggesting that it acts in a pathway(s) distal to activation of fos gene expression. The possible inhibitory mechanisms of action of dexamethasone on E(2)-stimulated DNA synthesis are discussed.

3T3 Cells↗

Approaches to the management of systemic lupus erythematosus.

Systemic lupus erythematosus is a difficult disease to study with a variable disease course characterized by exacerbations and remissions. A variety of biologic agents are under investigation as potential treatments for systemic lupus erythematosus, either in murine disease models or in clinical trials. These products are designed to specifically interfere with the following immunologic processes: T-cell activation and T-cell-B-cell collaboration, production of anti-dsDNA antibodies, deposition of anti-dsDNA antibody complexes, complement activation, and deposition, and cytokine activation and modulation. More aggressive interventions include gene therapy and stem-cell transplantation. Recently developed immunomodulators have been studied in patients with systemic lupus erythematosus 2'-Chlorodeoxyadenosine, mycophenolate mofetil, and leflunomide. Additional innovative pharmaceutical treatments include the mild androgen dehydroepiandrosterone, estrogen antagonists, including tamoxifen and selective estrogen receptor modulators, and the prolactin inhibitor bromocriptine. Other promising pharmaceutical interventions include products designed to inhibit synthesis of the proinflammatory mediators: prostaglandins, leukotrienes, and nitric oxide. Although previously regarded as an indication to be avoided in the development of new therapeutics, enthusiasm for studying systemic lupus erythematosus in clinical trials now exists. A variety of biologic and pharmaceutical agents offer promise as potential therapies. As with rheumatoid arthritis, development of these products will benefit from active involvement of rheumatologists and efforts to develop international consensus regarding trial methodology and outcome measures.

Animals↗

Osteoporosis: intervention options.

Osteoporosis is a systemic progressive disease with important clinical complications because of the fractures that arise and cause major morbidity in especially the aging postmenopausal women. Because of the relative not complex procedure of diagnosis and prediction the most important question to answer: is treatment possible? There are now a variety of treatments available for the management of osteoporosis. The inhibitors of bone resorption, which include calcium, the vitamin Ds, bisphosphonates, calcitonins and gonadal steroids have been variously shown to prevent bone loss or to reduce fractures. On the other hand bone formation stimulating agents as fluorides and in the near future parathyroid hormone and analogues must be considered also. However, randomized clinical trials with fractures as clinical endpoints are only few in number and not present for every suggested treatment. During the last 3 years it has become clear that besides estrogen, bisphosphonates and now perhaps the selective estrogen receptor modulators also show a good alternative as intervention option of postmenopausal osteoporosis. At this moment sodium fluoride is not the first choice in treatment of osteoporosis in general practice.

Calcitonin↗

Modulation by estrogen-receptor directed drugs of 5-hydroxytryptamine-2A receptors in rat brain.

Hormonal specificity of modulation of brain 5-HT(2A) receptors was investigated by comparing activity of compounds with varying effects on estrogen response in breast, bone, and uterus. A two-week estradiol treatment stimulated the decreased uterine weight of ovariectomized rats to intact rat values whereas an increase of 29% with tamoxifen and 16% with raloxifene was observed compared to vehicle-treated ovariectomized rats. In 18 assayed brain regions, ovariectomy decreased 5-HT(2A) receptor binding and mRNA levels in anterior cingulate and frontal cortices, striatum, and nucleus accumbens; estradiol restored this decrease to intact rat values. Dehydroepiandrosterone (DHEA) increased ovariectomized rats 5-HT(2A) receptor expression only in striatum and cortical amygdala. Tamoxifen increased 5-HT(2A) receptor density only in striatum. Raloxifene, an uterine estrogen receptor (ER) antagonist, increased, like estradiol, 5-HT(2A) receptor density and expression in cingulate and frontal cortices, striatum, and nucleus accumbens. Brain regional specificity of estradiol, DHEA, tamoxifen, and raloxifene on 5-HT(2A) receptors was observed which can be dissociated from peripheral activity.

Adjuvants, Immunologic↗

CREB binding protein acts synergistically with steroid receptor coactivator-1 to enhance steroid receptor-dependent transcription.

Steroid receptors are ligand-regulated transcription factors that require coactivators for efficient activation of target gene expression. The binding protein of cAMP response element binding protein (CBP) appears to be a promiscuous coactivator for an increasing number of transcription factors and the ability of CBP to modulate estrogen receptor (ER)- and progesterone receptor (PR)-dependent transcription was therefore examined. Ectopic expression of CBP or the related coactivator, p300, enhanced ER transcriptional activity by up to 10-fold in a receptor- and DNA-dependent manner. Consistent with this, the 12S E1A adenoviral protein, which binds to and inactivates CBP, inhibited ER transcriptional activity, and exogenous CBP was able to partially overcome this effect. Furthermore, CBP was able to partially reverse the ability of active ER to squelch PR-dependent transcription, indicating that CBP is a common coactivator for both receptors and that CBP is limiting within these cells. To date, the only other coactivator able to significantly stimulate receptor-dependent transcription is steroid receptor coactivator-1 (SRC-1). Coexpression of CBP and SRC-1 stimulated ER and PR transcriptional activity in a synergistic manner and indicated that these two coactivators are not functional homologues. Taken together, these data suggest that both CBP and SRC-1 may function in a common pathway to efficiently activate target gene expression.

CREB-Binding Protein↗

Benefits of complete polyamine deprivation in hormone responsive and hormone resistant MCF-7 human breast adenocarcinoma in vivo.

Polyamines are ubiquitous cellular compounds which are required for estradiol induced proliferation in breast cancer. Complete polyamine deprivation, using 2 alpha-difluoromethyl-ornithine (DFMO, Eflornithine), a specific inactivator of ornithine decarboxylase (key-enzyme of the polyamine biosynthesis) combined with inhibition of the bacterial production of gastrointestinal polyamine and a polyamine free regimen, was demonstrated to exhibit a cytostatic effect and a decrease of the three tumoral polyamine concentrations in a MCF-7 tumor model. In this experiment, complete polyamine deprivation has been tested on a standard MCF-7 tumor and on a variant MCF-7 tumor (i.e. with a tamoxifen acquired resistance). Polyamine deprivation was effective on the tumor growth, both on standard and variant sub-types. The polyamine contents of two types of tumor were similar, and identically, polyamine deprivation has caused a decrease of putrescine, spermidine and also spermine tumoral concentrations measured by the HPLC method in standard and variant MCF-7 tumors. Acquired tamoxifen resistance is common in patients undergoing hormonal therapy for advanced breast cancer. It has been hypothesized that the direct stimulation of polyamine pathway without estradiol involvement could be one of the mechanisms responsible for the tamoxifen resistance. The ability of polyamine deprivation to inhibit the growth of tumors becoming tamoxifen resistant could offer a therapeutic advantage in case of tumor with acquired tamoxifen resistance and could be tested to prevent or delay the hormonal responsiveness to breast cancer.

Adenocarcinoma↗

Effects of raloxifene hydrochloride on the endometrium of postmenopausal women.

OBJECTIVE: We evaluated subtle endometrial morphologic changes in postmenopausal women assigned to placebo, raloxifene hydrochloride 200 or 600 mg/day, or conjugated estrogens (Premarin 0.625 mg/day) according to a new estrogenicity scoring system. Raloxifene, a new selective estrogen receptor modulator, was not expected to stimulate the endometrium. STUDY DESIGN: Baseline and end point endometrial biopsies were performed during this double-blind, placebo-controlled 8-week study. A scoring system that was based on standard glandular and stromal morphologic criteria was used to quantitate estrogen-induced effects. Baseline, end point, and baseline-to-end point changes were analyzed for treatment differences. RESULTS: Treatment groups were similar at baseline with most women showing no estrogenic effects. At end point, statistically significant moderate and marked estrogenic effects were noted in 77% of estrogen-treated women versus 15% of placebo-treated women versus 0% of raloxifene-treated women. CONCLUSIONS: As expected, estrogen treatment stimulated postmenopausal endometrium. In contrast, raloxifene did not induce histopathologic evidence of endometrial stimulation in healthy postmenopausal women.

Biopsy↗

Nongenomic regulation of the kinetics of exocytosis by estrogens.

The role of nongenomic action of estrogens on elicited catecholamine secretion and exocytosis kinetics was studied in perfused rat adrenals and in cultured bovine chromaffin cells. 17beta-Estradiol as well as the estrogen receptor modulators raloxifene and LY117018, but not 17alpha-estradiol, inhibited at the micromolar range the catecholamine output elicited by acetylcholine or high potassium. However, these agents failed to modify the secretion elicited by high Ca(2+) in glands treated with the ionophore A-23187 (calcimycin), suggesting that estrogens did not directly act on the secretory machinery. At the single cell level, estrogens modified the kinetics of exocytosis at nanomolar range. All of the drugs tested except 17alpha-estradiol produced a profound slowing down of the exocytosis as measured by amperometry. LY117018 also reduced the granule content of catecholamines. 17beta-Estradiol reduced the intracellular free Ca(2+) but only at micromolar concentrations, whereas nanomolar concentrations increased the cAMP levels. These effects were reproduced with the nonpermeable drug 17beta-estradiol-horseradish peroxidase and antagonized with nanomolar concentrations of the antiestrogen ICI 182,780 (fulvestrant). Our data suggest the presence of membrane sites that regulate both the exocytotic phenomenon and the total catecholamine release with high and low affinity, respectively.

Adrenal Glands↗

Regulation of pS2 gene expression by affinity labeling and reversibly binding estrogens and antiestrogens: comparison of effects on the native gene and on pS2-chloramphenicol acetyltransferase fusion genes transfected into MCF-7 human breast cancer cells.

We have examined the effects of reversibly and irreversibly binding estrogenic and antiestrogenic ligands for the estrogen receptor on pS2 RNA accumulation in MCF-7 human breast cancer cells and on pS2-chloramphenicol acetyl transferase (CAT) fusion gene expression in transfected MCF-7 cells. In MCF-7 cells grown in the absence of estrogens, the reversibly binding estrogen, estradiol, and the affinity labeling estrogen, ketononestrol aziridine, KNA, evoked a 13-fold increase in pS2 RNA level. The reversibly binding antiestrogen trans-hydroxytamoxifen and the affinity labeling antiestrogens tamoxifen aziridine or desmethylnafoxidine aziridine behaved as partial agonists/antagonists. In thymidine kinase-chloramphenicol acetyltransferase (tk-CAT) fusion genes containing a 1000 base pair fragment of the pS2 5'-flanking region encompassing the estrogen responsive element of the gene [pS2 (-1100/-90) tk-CAT], estradiol and ketononestrol aziridine evoked a marked stimulation of CAT activity and, in transfected cells grown in both the presence or absence of the weak estrogen phenol red, the antiestrogens behaved as partial agonists/antagonists. This pS2 5'-flanking region displayed both estrogen-dependent and estrogen-independent enhancer activity as monitored by stimulation of CAT activity. Hormonal regulation of the transfected pS2 fusion gene was similar to that observed in the native pS2 gene of MCF-7 cells; however, antiestrogens, while still partial agonists-antagonists, were relatively more agonistic on the transfected fusion gene than on the native gene. One antiestrogen (ICI 164,384) that behaved as a pure estrogen antagonist on the native gene was a partial agonist-antagonist of pS2 gene expression in the plasmid. This study illustrates that the hormonal regulation of the pS2 gene, as characterized by the agonist-antagonist balance of estrogens and antiestrogens, is influenced by the DNA context of the pS2 estrogen responsive element. Also, the fact that estrogens and antiestrogens that form covalent bonds with the estrogen receptor modulate activity of the native pS2 gene and the pS2-tk-CAT fusion gene in a manner similar to that of their reversibly binding counterparts suggests that it may be possible to use these irreversibly binding ligands to follow the interaction of hormone-receptor complexes with regions regulating estrogenic stimulation of the pS2 gene.

Affinity Labels↗

The importance of patient education in improving compliance.

It is self-evident that the benefits of hormone replacement therapy will not be realized if women do not continue taking the therapy for long enough. All surveys show very disappointing levels of compliance or continuance, with typically about 25% of women stopping within 6 months and very few remaining on therapy for more than 1 or 2 years. The main reasons for stopping include unexpected or unacceptable side-effects, bleeding, fears of cancer, ignorance of the effects of hormone replacement therapy and the potential benefits, inappropriate expectations and poor support from medical advisers. With the ever-increasing options for prescribing hormone replacement therapy, including different routes of administration, combinations of hormones and variable dosages, it should be possible to find a regimen of hormone replacement therapy to suit most women. In the long term, poor continuation of hormone replacement therapy is strongly influenced by the presence of bleeding. Continuous combined estrogen/progestogen regimens, which avoid cyclical bleeding, are more acceptable, particularly for the older postmenopausal woman. However, the initial counselling has a most important impact and time taken to explain and to involve the woman in the decision process will encourage greater confidence in the merits of the therapy. The use of informative literature, videos and telephone help-lines, together with regular and close follow-up until a regimen is satisfactorily established, allows reassurance about initial side-effects or worries and adjustment of therapy. Recent developments of lower-dose combination therapy, selective estrogen receptor modulators and intrauterine progestogen-releasing systems should further improve compliance, but the key to continuation with hormone replacement therapy is a well-informed and confident patient.

Aged↗

Breast cancer prevention by antiestrogens.

A new era has been entered with the first demonstration that an antiestrogen can prevent breast cancer. In a landmark study tamoxifen was shown to reduce the incidence of breast cancer by approximately 50%. The reduction was observed in pre- and postmenopausal women at increased risk of breast cancer. Invasive cancers were reduced, the reduction being in the estrogen receptor-positive cancers. No preventive effect was observed for estrogen receptor-negative tumors. In situ cancers were also significantly reduced. A collateral benefit was a significant reduction in fractures due to osteoporosis. Adverse effects included a very small increase in the incidence of endometrial cancer, cataracts, and stroke. The benefits appear to outweigh the risks for those at high risk. Preliminary studies of a new selective estrogen receptor modulator (SERM 2), raloxifene, developed for the prevention of osteoporosis, have shown that the breast cancer rate was reduced by more than 50% without any concomitant increase in endometrial cancer. The search for a SERM 3, and beyond, may lead to the development of drugs that have the beneficial effects of estrogen while preventing breast cancer and osteoporosis.

Antineoplastic Agents, Hormonal↗

Gonadotropins stimulate growth of MCF-7 human breast cancer cells by promoting intracellular conversion of adrenal androgens to estrogens.

Estrogen receptor (ER)-positive breast cancers initially respond well to estrogen ablation treatment but finally acquire refractoriness, the phenomenon that is a major clinical problem. Because some breast cancers synthesize estradiol (E(2)) and E(2) synthesis is regulated by gonadotropins in normal ovaries, and because circulating gonadotropins are elevated in postmenopausal women and during estrogen ablation treatment, we hypothesized that gonadotropins might modulate estrogen synthesis/metabolism in breast cancer tissue as well. To test this possibility, MCF-7 cells were treated with dehydroepiandrosterone (DHEA) or human chorionic gonadotropin (hCG; approximately LH), each alone or in combination. Cell growth (3-day treatment) was assayed by the MTT method and estrogen synthesis (24-hour treatment) was measured using the ERE-luciferase reporter system. First, MCF-7 cell growth was stimulated by DHEA in a concentration-dependent manner with a maximal effect at 10(-4) M. Although hCG alone did not have a significant proliferative effect, hCG significantly and dose dependently stimulated MCF-7 cell growth in the presence of a submaximal concentration of DHEA (10(-7 )M). This stimulatory effect of DHEA and hCG was blocked by a pure antiestrogen ICI182,780 and an aromatase inhibitor, arimidex. Using MCF-7 cells transfected with the ERE-luciferase reporter system, hCG treatment was shown to increase ERE-mediated transcription. These results indicate that MCF-7 cells intrinsically converted DHEA into E(2) upon hCG stimulation, then grew their own cells DHEA- and hCG-dependently. We conclude that gonadotropins can act on breast cancer cells and accelerate conversion of DHEA into estrogens, thereby stimulating growth of estrogen-dependent tumor cells. This phenomenon, at least in part, could explain: (1) an increased tissue concentration of E(2) in postmenopausal breast cancer; (2) acquisition of hormone refractoriness during estrogen ablation treatment, and (3) the effectiveness of GnRH antagonist/superagonist in some postmenopausal breast cancer patients.

Anastrozole↗

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↗

Postmenopausal hormone replacement, risk estimators for coronary artery disease and cardiovascular protection.

Menopause, regardless of age at onset, is associated with a marked increase in coronary artery disease (CAD) risk. A large body of observational clinical studies repeatedly demonstrated favorable associations between postmenopausal hormone replacement therapy (HRT) and cardiovascular morbidity, mortality, and risk factors. Estrogens may act in a gender-specific way on vascular endothelial cells and other components of the vessel wall, enhancing the synthesis and release of nitric oxide (NO) and other vasodilators, and by inhibiting the synthesis and release of vasoconstricting agents, thus favoring vasodilation. Menopause-related changes in metabolic cardiovascular risk factors are identifiable, as are HRT-related changes in these factors. The metabolic effects include changes in lipoprotein (a), coagulation and fibrinolysis as well as homocysteine metabolism. The various actions of estrogen alone and combined with progestogen on the vascular system are reviewed. Furthermore, the outcome of the recently published Heart and estrogen/progestin replacement study (HERS) data are put in perspective. In addition, we outline the present data on the effects of raloxifene, a new second generation selective estrogen receptor modulator (SERM), which has been shown to favorably alter several markers of cardiovascular risk in postmenopausal women.

Animals↗

Clinical development of estrogen modulators for breast cancer chemoprevention in premenopausal vs. postmenopausal women.

Tamoxifen has proven to be beneficial in the chemoprevention of breast cancer in women at increased risk for the disease. Other compounds that mediate the estrogen pathway remain to be tested for clinical efficacy. The mechanism of action, efficacy, and dose response of the estrogen modulators is determined by the hormonal milieu of the host which should be considered in the early clinical trials for dose range finding studies and surrogate endpoint biomarker (SEB) evaluation. This review presents the hormonal effects to consider in the clinical testing of an agent in premenopausal vs. postmenopausal cohorts. Recommended SEBs that may be evaluated in Phase I/II clinical trials of estrogen modulators for breast cancer chemoprevention are presented.

Aromatase Inhibitors↗

Osteoporosis: detection, prevention, and treatment in primary care.

Osteoporosis is a silent disease that often remains asymptomatic and undetected until bone fracture occurs. Because of the high morbidity associated with fracture, prevention is a clinical priority. In order to identify those who would benefit from therapeutic intervention, bone density measurement is indicated in patients with risk factors for osteoporosis. Therapies include hormone replacement, calcitonin, bisphosphonates, and selective estrogen receptor modulators, as well as exercise and supplements of calcium and vitamin D. The goal of all treatments is to decrease the risk of fracture by minimizing bone loss and increasing bone mass.

Aged↗

Tissue-specific estrogen biosynthesis and metabolism.

While the ovaries are the principal source of systemic estrogen in the premenopausal nonpregnant woman, other sites of estrogen biosynthesis are present throughout the body and these become the major sources of estrogen beyond menopause. These extragonadal sources of estrogen are small, but may play an important, though hitherto largely unrecognized, physiological and pathophysiological role. Aromatase activity in extragonadal sites contributes to this source of estrogen and may contribute to breast tumor development and/or growth. Selective aromatase modulators (SAMs) may have a role to play in the treatment of estrogen-dependent diseases, such as breast cancer.

Animals↗