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At least 19 recordsLinked to original sources
PubMed1975

Estrogen and estrogen receptors of breast cancer.

Human breast cancer can be divided into a group that contains specific receptor sites for estrogen and a group without such specific estrogen-binding sites. The presence of specific estrogen receptors in some tumors indicating hormonal dependency has been shown to be of predictive value for endocrine treatment. This would greatly improve therapeutic planning for patients with breast cancer. Tumor tissue from 52 patients was investigated for content of both cytosol estrogen and estrogen receptor. In addition, the total tumor estrogen was also determined in 14 of these tumors. The results of this investigation show two distinct groups: one group containing both estrogen receptor and estrogen and a second group with no receptor but with measurable amount of estrogen. Tumors with estrogen receptors have higher tissue levels of estrogen than tumors without specific estrogen receptor. Even in the absence of estrogen recptor, however, most tumor tissue examined contained a measurable amount of estrogen.

Breast Neoplasms↗
PubMed1979

Plasma concentrations of unconjugated and conjugated estrogens and gonadotrophins following application of various estrogen preparations after oophorectomy and in the menopause.

In 55 patients after oophorectomy and 20 women after natural menopause an oral estrogen replacement therapy was performed with estrone-sulfate, estradiol 17-valerate, estriol-succinate, a combination of micronized estradiol and estriol (Estrifam, Trisequens), and natural conjugated estrogens. In 4 patients a 3 mg estradiol per 5 g ointment substance was applied on the abdominal skin. The interindividual variations of estrogen increments during therapy were considerably high. Oral intake of 2 mg estriol-succinate daily was followed by a 500% increase of total (conjugated + unconjugated) estriol. Concentrations of unconjugated estrogens were not altered by this dosage. Following oral application of the other above mentioned preparations, prominent rises--especially of unconjugated estrogens in plasma--were noted. The concentration peaks occurred within 3--6 h after application. Unconjugated estradiol-17 beta in plasma was comparable with values of the follicular phase of a normal menstrual cycle, unconjugated estrone, however, was nonphysiologically high. Consequently, the E1/E2 ratio was greater than one whereas it is normally below one. 12 h after oral estrogen application, plasma estrogens dropped to almost initial values, so that a second medication seems to be necessary in order to guarantee an adequate supplementation over the course of the day. The hormone values determined in this study did not show significant differences between patients after a natural menopause and after oophorectomy. There was a positive correlation between rising estrogen levels and suppressed gonadotrophins during replacement therapy. The occurrence of climacteric symptoms did not exclusively depend on low estrogen and high gonadotrophin levels. Good tolerance of estrogen therapy with significantly elevated estrogen concentrations in plasma can be obtained transcutaneously in the form of estrogen ointments. Such therapy might simulate the physiological estrogen pattern even better than oral application does because of delayed and diluted steroid flow to the liver.

Castration↗
PubMed1975

Synthesis and inducibility of the Uterine estrogen-induced protein, IP, during the rat estrous cycle: clues to uterine estrogen sensitivity.

Analysis of newly labeled soluble proteins in uteri of mature rats throughout the estrous cycle indicates that the relative rate of synthesis of the uterine estrogen-induced protein, IP, is high at proestrus, when endogenous estrogen secretion is maximal; it is not synthesized at detectable levels at estrus and metestrus; and some minimal synthesis is seen in diestrus uteri. Injection of exogenous estrogen results in some increase in the IP synthesis rate at proestrus; slight induction of IP synthesis at estrus; and maximal induction (as great as that induced in the mature, ovariectomized uterus by estrogen) at metestrus and diestrus. Studies in the immature (day 21-24) rat, aimed at determining the possible causes of the uterine recalcitrance to exogenous estrogen seen at estrus, indicate that one can reproduce in the immature uterus a period of feeble responsiveness to a second injection of estrogen after exposure to a first, high dose of estrogen. After a single injection of estrogen, there is a lag between the gradual return of full IP inducibility (requiring over 40 hours to reach the control level) and the return of nuclear-translocatable receptor (at control level by 24 hr). This suggests that in addition to the presence of nuclear-translocatable receptor, the response to a second injection of estrogen is dependent upon other factors whose replenishment and/or reactivation is slower than that of the receptor.

Age Factors↗
PubMed1975

In vivo effect of anti-estrogens on the localisation and replenishment of estrogen receptor.

Interactions between estrogen recpetors and triaryl ethylene anti-estrogens (U-11100A, MER 25 and CI 628) were tested on immature rat uteri. The accessible and the total (accessible and occupied) estrogen receptor sites were assayed in the cytosol and nuclear extracts using charcoal adsorption. After in vivo administration of anti-estrogens, the estradiol receptor sites were occupied and subsequently transferred to the nuclear compartment. The nuclear localisation of the receptor induced by the antagonist lasted for several days, during which replenishment of the cytosol receptor occurred. The nuclear receptors transferred by anti-estrogens and labelled in vitro with [3H]estradiol, were similar to the nuclear receptor-estradiol complex formed in vivo as far as their sedimentation constants and extractability from nuclei were concerned. Although these anti-estrogens are capable to translocate the estrogen receptor to the nucleus and to induce the replenishment of the cytosol receptor, the mechanism of their antagonism and of their weak estrogenic activity is still not clear.

Animals↗
PubMed1975

On the mechanism of prolactin and estrogen action in 7,12 dimethylbenz(A)anthracene-induced mammary carcinoma in the rat. II. In vivo tumor responses and estrogen receptor.

In order to test the in vivo effect of prolactin on estrogen receptor (ER) binding capacity in tumors induced by 7,12 dimethylbenz(a)anthrancene (DMBA-tumor), growth of the tumors from changes in prolactin and estrogen levels was compared retrospectively with cytoplasmic ER levels. It was demonstrated that some tumors required prolactin, some needed prolactin-estrogen during their growth period anda small number were not influenced by hormonal milieu. ER was present in hormonally dependent tumors but was low or absent in hormonaly-independent tumors. Deletion of hormones by endocrine ablation in the host rat resulted in tumor regression loss of ER. Replenishment of ER and subsequent tumor growth were accomplished by injection of prolactin or prolactin-estrogen in endocrine ablated rats but were not achieved in rats bearing tumors exposed to prolactin-nafoxidine. Our results demonstrate that both estrogen and prolactin were essential for growth of hormonally dependent DMBA-tumors. Tumor growth was also prevented when cytoplasmic ER was not replenished , indicating that ER may be an indispensable prerequisite for growth. Prolactin, independently of or cooperatively with estrogen, stimulated ER binding capacity. These results support the hypothesis that there may exist a prolactin regulatory mechanism of estrogen action at the tumor site. The interactions of estrogen and prolactin in situ in modulating hormonal receptor binding capacities may contribute to the overall stimulatory effect of these two hormones on DMBA-tumors.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1975

The affinity of catechol estrogens for estrogen receptors in the pituitary and anterior hypothalamus of the rat.

The purpose of these experiments was to evaluate the potential for interaction between 2-hydroxyestrone and 2-hydroxyestradiol and estrogen receptors in rat pituitary and anterior hypothalamus. The 150,000 X g supernatant fractions of these tissues were prepared, the estrogen receptor-site concentration was measured, and the relative abilities of unlabelled estradiol, estrone, 2-hydroxyestradiol and 2-hydroxyestrone to compete with [3H]estradiol for estrogen binding sites was determined. From these results, and the previously determined association constant for [3H]estradiol, 10(10)M-1, the association constants of the other estrogens were calculated. The introduction of the 2-hydroxy group caused only a modest reduction in the affinity of these estrogens for the receptors. The association constants of the 2-hydroxy derivatives were within one order of magnitude of those of the parent compounds. These results demonstrate the potential for interaction between catechol estrogens and estrogen receptor in rat brain and pituitary of a magnitude which could be biologically significant.

Animals↗
PubMed1975

Ultraviolet photosensitivity of the estrogen binding protein from rat uterus. Wavelength and ligand dependence. Photocovalent attachment of estrogens to proteins.

Ultraviolet irradiation of the estrogen binding protein in rat uterine cytosol results in a progressive photoinactivation which is rapid at 254 nm and slower at greater than 315 nm. Both unfilled and estradiol-filled sites are inactivated at approimately the same rates at 254 nm (t 1/2 equals 8 min and 11 min, respectively), but at 315 nm, empty sites are consumed much more rapidly (t 1/2 equals 3.4 hr) than filled ones (t 1/2 equals 24 hr). The protective effect of the estrogen ligand at this wavelength appears to depend on its binding to the estrogen-specific binding site, as inactivation rate studies at different concentrations of estrone, estradiol, and estriol show a good correlation between the extent of protection and the fractional saturation of the high affinity estrogen binding sites. Scatchard analysis indicates that inactivation is the result of a loss of binding sites and not a decrease in their affinity, and sedimentation analysis shows that increased heterogeneity and aggregation of the estrogen binding species accompanies the photoinactivation process. Photoinactivation appears to be the result of direct irradiative damage of the animo acid residues, as the inactivation rate is the same under air and nitrogen atmospheres, and is unaffected by nucleophiles, reductants, and radical scavengers. When photoinactivation is measureed by irradiation of cytosol containing [3-H]estradiol, a concurrent photocovalent attachment process is noted; the steroid becomes linked to protein in a solvent-extractable manner (boiling ethanol inextractable). This attachment, however, does not appear to be related to the steroid binding at the estrogen binding site. Its rate is affected by reductants and scavengers. A similar photocovalent attachment reaction occurs when bovine serum albumin or ovalbumin is irradiated in the presence of [3-H]estradiol or [3-H]diethylstilbestrol. The detailed reactions involved in this photocovalent attachment process have not been defined at present.

Animals↗
PubMed1979

Estrogenic activity of the insecticide chlordecone (Kepone) and interaction with uterine estrogen receptors.

The chlorinated insecticide chlordecone (Kepone) interacts with the estrogen receptor system in the rat uterus in vitro and in vivo. It competes with estradiol for binding to the cytoplasmic receptor in vitro and also induces nuclear accumulation of estrogen receptor sites in uteri in vitro. When injected into immature rats, chlordecone translocates estrogen receptor sites to the uterine nucleus, increases uterine weight, and stimulates the synthesis of the progesterone receptor, an estrogen receptor-mediated process. Its slow onset of action but prolonged duration of interaction with estrogen receptor and stimulation of uterine weight gain and progesterone receptor synthesis indicates that, although it has an affinity for receptor only 0.01-0.04% that of estradiol, its considerable estrogenic activity may likely be derived from its long half-life and bioaccumulative character.

Animals↗
PubMed1976

Estrogen-receptor binding: relationship to estrogen-induced responses.

The relationship between nuclear binding of the receptor-estrogen complex (R-E) and estrogenic responses was examined. Nuclear-bound R-E was measured by the [3H] estradiol exchange assay, which permits the quantification of R-E as a function of either endogenous or non labeled estrogen. The quantity of nuclear R-E fluctuated as a function of blood levels of estrogen during the estrous cycle in the rat. This indicates that the accumulation of the R-E complex by the nucleus of uterine cells may be of physiologic significance and under the control of endogenous estrogen.

Animals↗
PubMed1978

Hepatic estrogen and progesterone receptors in an estrogen-associated hepatic neoplasm.

A patient with a benign hepatic neoplasm developing after treatment with estrogenic hormones is described. After excision, the neoplastic tissue was analyzed for the presence of cytosol estrogen and progesterone binding proteins. The neoplasm was classified as focal nodular hyperplasia of the liver and was demonstrated to contain high-affinity cytosol estrogen and progesterone hormone receptors. The estrogen-binding affinity of the neoplasm was three times greater than that of normal liver. Further investigation of cytosol hormone receptors in estrogen associated hepatic neoplasms will be required to define the role of these binding proteins in the possible etiology of certain liver tumors.

Clinical Trials as Topic↗
PubMed2014

Upregulation of TLR2 expression is induced by estrogen via an estrogen-response element (ERE).

TLR2 and estrogen are both thought to be involved in the pathogenesis of RA; however, it is unknown if there is an association between estrogen and TLR2. In this report, we treated PMA-differentiated THP-1 cells with 17β-estradiol (E2) and observed increases in TLR2 mRNA and protein levels by real-time quantitative PCR and western blot. Transfection of THP-1 cells with a series of 5'-deleted TLR2 promoter-luciferase constructs revealed that E2 enhanced TLR2 transcriptional activity in an estrogen receptor alpha (ERα)-dependent pattern. An estrogen receptor response element (ERE) was identified 251 bases upstream of the TLR2 promoter, and electrophoretic mobility shift assay and chromatin immunoprecipitations showed ERα binding was increased by E2. In summary, this work demonstrated that TLR2 is a new estrogen-regulated gene whose expression is upregulated through the interaction of ERα with an ERE in the promoter region.

Cell Line↗
PubMed2019

Estrogen-independent molecular actions of mutant estrogen receptor 1 in endometrial cancer.

Estrogen receptor 1 (ESR1) mutations have been identified in hormone therapy-resistant breast cancer and primary endometrial cancer. Analyses in breast cancer suggest that mutant ESR1 exhibits estrogen-independent activity. In endometrial cancer, ESR1 mutations are associated with worse outcomes and less obesity, however, experimental investigation of these mutations has not been performed. Using a unique CRISPR/Cas9 strategy, we introduced the D538G mutation, a common endometrial cancer mutation that alters the ligand binding domain of ESR1, while epitope tagging the endogenous locus. We discovered estrogen-independent mutant ESR1 genomic binding that is significantly altered from wild-type ESR1. The D538G mutation impacted expression, including a large set of nonestrogen-regulated genes, and chromatin accessibility, with most affected loci bound by mutant ESR1. Mutant ESR1 is distinct from constitutive ESR1 activity because mutant-specific changes are not recapitulated with prolonged estrogen exposure. Overall, the D538G mutant ESR1 confers estrogen-independent activity while causing additional regulatory changes in endometrial cancer cells that are distinct from breast cancer cells.

CRISPR-Cas Systems↗
PubMed1978

Replacement estrogen therapy for menopausal vasomotor flushes. Comparison of quinestrol and conjugated estrogens.

Quinestrol, conjugated estrogens, or placebo was used to treat 156 patients with pernicious vasomotor instability in a prospective, double-blind, randomized, multiinvestigator trial. Vasomotor flushes were severe in approximately 80% of the cases and moderate in 20%, relatively equally distributed among the various drug groups. Both qinestrol and conjugated estrogens were significantly more effective than placebo in relieving vasomotor symptoms (by chi2 analysis, P less than or equal to 0.05). Greatest improvement was seen in the group receiving the higher once weekly quinestrol dosage of 0.2 mg followed by the group on the lower quinestrol dosage of 0.1 mg once weekly and the group on conjugated estrogens, 1.25 mg daily for 21 days on and 7 days off. No significant difference in relief of vasomotor flushes was shown between the active drug groups. No drug-related complications or side reactions of significance occurred. The results indicate that once weekly quinestrol is effective in relieving the vasomotor symptoms of the menopause. Either of two once weekly quinestrol regimens is an effective as conjugated estrogens given daily in a cyclic manner and therefore offers an alternative form of exogenous estrogen therapy.

Chemical Phenomena↗
PubMed1976

Plasma precursors of estrogen. III. Conversion of plasma dehydroisoandrosterone to estrogen in young nonpregnant women.

The utilization of plasma dehydroisoandrosterone for estrogen production was studied in 4 normal young nonpregnant women and in one young surgical castrate woman. The mean transfer constant for total conversion to estrogen, [sigma] DE-BU' was 0.0016 of which about one third (0.0005) could be accounted for by conversion of dehydroisoandrosterone first to plasma androstenedione which in turn was converted to estrone. The remaining fractional conversion appeared to result principally in estradiol formation via a pathway probably not involving plasma androstenedione. The conversion of plasma dehydroisoandrosterone to estrogen was similar in the surgical castrate to that observed in the ovulating women. It is concluded that plasma dehydroisoandrosterone is converted to estrogen at extraglandular site(s) but this contribution represents only a minor fraction of total estrogen production in normal young women.

Androstenedione↗
PubMed1977

Blood production rates of estrogens in women with differing ratios of urinary estrogen conjugates.

On the basis of the ratios of the estrogen conjugates in their urine (estriol/estrone + estradiol: E3/[E1+E2]), 19 women were divided into two groups: 9 women had ratios less than 0.6 and 10 women had ratios greater than 1.3. All women had measurements made of endogenous estrogens in their plasma by radioimmunoassay. They were then given constant infusions of 3H-estrone, 3H-estradiol and 14C-estriol during days 5-7 and days 20-22 of their cycles, and metabolic clearance rates (MCR) and blood production rates (PB) of estrone, estradiol and estriol were determined. Despite the wide disparity in their ratios of urinary estrogens, no differences could be found between the groups for the MCR's and PB's for all estrogens at either time of the cycle. The mean ratios of PB's (PB3/[PB2+PB1]) of estrone, estradiol and estriol ranged from 0.07 to 0.10 for each group during the cycle. The amounts of estriol entering the blood are small compared to the amounts of estrone and estradiol and do not correlate with the ratios of their urinary conjugates.

Adult↗
PubMed1977

Human breast cancer: biologically active estrogen receptor in the absence of estrogen?

The human breast cancer cell line MCF-7 does not require estrogen for growth, but paradoxically its growth is inhibited by antiestrogens. Our results show that, unlike normal target cells, MCF-7 cells carry most of their estrogen receptors in their nuclei even when these receptors are not charged with estrogens. The receptors for androgen and for progesterone, on the other hand, are localized in the cytoplasm as usual. Therefore, it is possible that the growth of these abnormal cells is stimulated by estrogen receptor in spite of the absence of the hormone and that the binding of antiestrogen molecules antagonize this stimulation.

Breast Neoplasms↗
PubMed1978

[Effects of several estrogenic compounds on serum corticosteroid-binding globulin (CBG) and the estrogen thresholds for increasing CBG (author's transl)].

The effects of several estrogen substances--alone, or in combination with norgestrel--on serum CBG in humans are reported in this paper. CBG was measured by a modified charcoal adsorption technique. Daily oral doses of Premarin, from 0.3 to 2.5mg, were given to healthy postmenopausal women for 14 days. Dose-dependent increases in CBG-BC were observed. Ovral, which contains ethinylestradiol and norgestrel, also induced significant increases in the levels of CBG-BC. Similar results were seen with Lo Ovral, but it had less influence than Ovral. When given alone, daily for 21 days, norgestrel had no effect on CBG-BC. The maximum rise of serum CBG-BC was found after 10 days of the daily doses of Ovral, and then the levels remained quite constant during the period of treatment. Exogenous estrogens of other types also caused increases in CBG-BC. The response of CBG to exogenous estrogens is of use in comparing the estrogen potencies of the compounds. CBG-BC levels remained constant throughout the menstrual cycle in five normal women despite fluctuating levels of estradiol which reached peaks of 190 approximately 430 pg/ml. In pregnant women and in HMG-treated women, however, serum levels of CBG-BC increased beginning when estradiol levels were greater than 1 ng/ml.

Adult↗