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B S Katzenellenbogen

Publications and source records attributed to B S Katzenellenbogen.

At least 199 records · Page 11Linked to original sources
PubMed1977

A comparative study of antiestrogen action: temporal patterns of antagonism of estrogen stimulated uterine growth and effects on estrogen receptor levels.

Studies were undertaken to ascertain the effects of structural modification of two well-known antiestrogens (CI-628 and U-11,100A) on their estrogenic and antiestrogenic potencies and temporal patterns of effectiveness in the immature rat uterus. Changes in the chemical structures of these anti-estrogens produce compounds with markedly different affinities for the uterine estrogen receptor as measured in an in vitro cell-free cytosol system; binding affinities relative to estradiol (100%) are: CI-628, 4%; CI-680, 34%; 94X1127 (94X),222%; U-11,100A (UA), 6%; and U-23,469 (U-23), 0.1%. Although all five antiestrogens (daily injections of 50 microng over three days) appear equally effective in stimulating 72 h uterine weight when given alone, or in blocking the estradiol-stimulated weight increase when given with estradiol, marked differences in their potencies are noted when the effects of the compounds are monitored beyond 24 h following a single injection. The compounds CI-628, CI-680 and UA (50 microng sc in saline), which have a methylated hydroxyl group (at the site analogous to the steroid position 3), show a prolonged maintenance of elevated levels of nuclear receptor (beyond 48 h) and elevated uterine weight (until 72 h); this correlates with a prolonged period of depressed cytoplasmic receptor levels (beyond 48 h) and prolonged uterine insensitivity to estrogen (beyond 36 h as monitored by 3 h wet weight response). In contrast, a single injection of 50 microng of 94X (having a free hydroxyl group) or U-23 (with a side chain and central ring different from UA) maintained nuclear receptor levels elevated for only 12 h (94X) or 36 h (U-23) and uterine weights declined after 36-48 h; cytoplasmic receptor levels remained depressed for only 12 h (94X) or 24 h (U-23) and then returned to control levels or above by 36 h. These latter compounds likewise evoked the shortest period of uterine insensitivity to estrogen (ineffective as antagonists by 36 h). Comparative studies with these five compounds indicate that they are effective as estrogen antagonists only so long as they maintain cytoplasmic receptor levels low, and that the magnitude of the responsiveness to estradiol after antiestrogen correlates with the extent of reappearance of cytoplasmic receptor. Thus, chemical modifications of antiestrogen structure have significant effects on their temporal patterns of effectiveness as estrogens and as estrogen antagonists.

Animals↗
PubMed1977

Fundamental differences in the action of estrogens and antiestrogens on the uterus: comparison between compounds with similar duration of action.

In order to understand differences in the mechanism of action of estrogens and antiestrogens, it is essential to make comparisons between compounds with similar duration of action. Hence, in these studies, we compare the action of a long-acting estrogen (17alpha-ethinyl estriol-3-cyclopentyl ether, EE3CPE) and a long-acting antiestrogen (U-11,100AUA) on the immature rat uterus and analyze different dosage regimens (single and multiple injections) in studying the effects of these compounds on the uterine estrogen receptor and on uterine growth and sensitivity to estradiol. During the first 24 h, UA (50 microng) and EE3CPE (5 microng) evoke remarkably similar receptor distribution patterns and uterine wet weight increase; however, pronounced differences are seen with long-term, multiple injection regimens (every 12 or 24 h for 72 h). Such treatment with UA results in maintenance of high nuclear receptor levels and very low cytoplasmic receptor levels (ca. 10% of total), but no further increase in uterine weight, DNA or protein content, or total receptor content beyond 24-48 h. In contrast, multiple injections of EE3CPE produce not only a prolonged nuclear retention of receptor, but a progressive increase in total receptor content in the tissue and 35-50% of total receptor is cytoplasmic; uterine weight and DNA and protein content also continue to increase markedly above the 24 h level, and responsiveness to estradiol is maintained. However, regardless of whether the uterus continues to grow (as the EE3CPE) or stops growing after 24-48 h (as with UA), the receptor content on a cell basis is similar. Hence, uterine responsiveness to estradiol and continued uterine growth appear not to be related to the total content of receptor per cell, but rather are correlated with the cytoplasmic receptor level within the cell. As there is a continuous translocation of cytoplasmic receptor to the necleus in the growing uterus, the antagonistic action of antiestrogens appears to derive from their ability to effect a marked perturbation in the subcellular distribution of receptor, whereby very little of receptor (ca. 10%) is cytoplasmic, and further estrogen receptor accumulation (most likely synthesis) is blocked.

Animals↗
PubMed1977

Antagonism of development and growth of 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors by the antiestrogen U 23,469 and effects on estrogen and progesterone receptors.

This study analyzed the effectiveness of a nonsteroidal antiestrogen, cis-(3-[p-(1,2,3,4-tetrahydro-6-methoxy-2-phenyl-1-naphthyl)phenoxy]-1,2-propanediol (U 23,469) previously shown to be potent in antagonizing estrogen-induced uterine growth, in preventing the development of 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumors and in eliciting the regression of established tumors; the study also attempts to elucidate the mechanisms of the tumor antagonism of U 23,469. Virgin female Sprague-Dawley rats that receive DMBA at 47 to 50 days of age and then receive U 23,469 (250 micrograms s.c. in 0.15 M NaCl daily) have a greatly reduced number of mammary tumors and a markedly decreased tumor area. Treatment with U 23,469 for increasing time periods (3, 6, or 12 weeks) beginning 2 weeks after DMBA results in a progressive delay in onset of tumor appearance. U 23,469 treatment beginning 1 week after DMBA or given prior to DMBA is even more effective. The time course of tumor regression (3 months after DMBA) by U 23,469 or ovariectomy is similar, with 50% regression in ca. 2 weeks, and both elicit regression of almost all tumors (greater than 90%). After ovariectomy, cytosol progesterone receptor levels are greatly diminished in tumors and uteri, while cytosol estrogen receptor (ER) levels are high; in both tissues little (ca. one-third) of ER is in the nucleus. During U 23,469 treatment, cytosol ER content is very low in regressing tumor and uterus and over 90% of ER is in the nucleus; cytosol progesterone receptor is slightly depressed in the uterus but is at the untreated level in mammary tumor. These receptor studies suggest that the effectiveness of this antiestrogen in antagonizing mammary tumor development and growth may reside in its ability markedly to perturb the distribution of ER, maintaining over 90% of ER in the nucleus with concomitant low levels of cytoplasmic ER, a situation that may render the mammary tissue insensitive to the animal's own endogenous estrogens.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1976

Temporal relationships between hormone receptor binding and biological responses in the uterus: studies with short- and long-acting derivatives of estriol.

The temporal relationships between hormone receptor binding and early and late biological responses in the uterus were examined using estriol (E3), a weak estrogen, and several more long-acting estriol derivatives, namely ethinyl estriol (EE3), estriol cyclopentyl ether (E3CPE), and ethinyl estriol cyclopentyl ether (EE3CPE). Dose-response curves of 3-day uterotrophic assays indicate that biological potency follows the order EE3CPE greater than EE3 or estradiol greater than E3CPE greater than E3. After a single injection of 5 mug of compound, E3 elicits the early uterotrophic responses (increased uterine wet weight and 2-deoxyglucose phosphorylation at 2-6 h) but gives only weak stimulation of later uterotrophic responses (enhanced rates of 2-deoxyglucose phosphorylation at 20-24 h and increased DNA synthesis rate and uterine weight over a 72 h period). E3, EE3, and estradiol all elicit a rapid (maximal by 1/2-1 h) uptake of receptor into the nucleus and show an equivalent wet weight response at 3 h. After E3, nuclear receptor levels and uterine weight decline rapidly; however, after EE3 or estradiol, nuclear receptor levels decline less rapidly remaining at least two-fold above the control until 24-48 hr, and uterine weight also remains elevated for at least 48-72 h. EE3CPE elicits both the early (4 h) and later (20-24 h) waves of glucose metabolism, shows a prolonged effect on DNA synthesis rate, and shows the most dramatic and prolonged (beyond 72 h) maintenance of elevated uterine weight and high nuclear receptor (beyond 24 h). Thus, chemical modifications of the estriol molecule which result in a prolonged stimulation of uterine growth and metabolism also result in a long-term maintenance of hormone-receptor complex in the uterine nucleus. These studies give strong support to the concept that true uterine growth requires the direct and prolonged influence of the nuclear estrogen-receptor complex.

Animals↗
PubMed1976

Androgen-uterine interaction: nuclear translocation of the estrogen receptor and induction of the synthesis of the uterine-induced protein (IP) by high concentrations of androgens in vitro but not in vivo.

High concentrations of androgens in vitro [10(-6) and 10(-7)M 5alpha-dihydrotestosterone (DHT) and testosterone (T)] translocate the estrogen receptor from cytoplasmic to the nuclear fraction of the immature rat uterus, and the androgen translocated sites are capable of eliciting the synthesis of the specific uterine "induced protein" (IP), formerly attributed to estrogenic compounds only. The magnitude of receptor translocation and IP synthesis induction is related to the concentration of androgen, and, at equal concentrations, DHT is more effective than T. Competitive protein-binding asssays with cell-free uterine cytosol indicate that DHT and T bind with barely detectable affinity to the cytosol estrogen receptor detectable affinity to the cytosol estrogen receptor [relative binding ability ca. 0.001% that of estradiol (E2)], and radioactive E2 uptake into whole uterus after pretreatment with androgens indicates that the androgen-translocated nuclear sites are readily filled by E2. DHT and T translocate the estrogen receptor to the nucleus in vitro, and the salt-extracted nuclear receptor is present as a 5 S ("transformed") receptor; however, concentrations of DHT and T that effect translocation are unable to elicit the heat-activated transformation of the estrogen receptor in cell free cytosol under conditions in which low concentrations of E2 fully transform the receptor. Under in vivo conditions, high levels of androgens (5--2,000 mug DHT or T) do not evoke any detectable translocation of the estrogen receptor and do not elicit any IP synthesis induction although uterine weight is increased (greater than 200 mug androgen) in long-term (2--3 day) assays. The analysis of androgen uptake and metabolism indicates that 500 mug or higher doses of DHT or T in vivo result in uterine concentrations of unmetabolized DHT or T equal to those seen after exposure to 5 X 10(-7) - 1 X 10(-6)M DHT or T in vitro. Hence, under conditions where in vivo and in vitro tissue uptake of androgen is equivalent, in vivo androgens are unable to affect the estrogen receptor system as is seen in vitro. These studies indicate that the in vitro and in vivo effects of androgens on the uterus are clearly different and suggest that the actions of androgens on the uterus in vivo are probably not directly mediated through the estrogen receptor system.

Animals↗
PubMed1975

Iodohexestrols. II. Characterization of the binding and estrogenic activity of iodinated hexestrol derivatives, in vitro and in vivo.

The affinity of ortho-iodinated hexestrols for the estrogen binding protein from rat uterus, determined by competitive binding assay, decreases with progressive iodine substitution; 3-iodohexestrol (I-Hex) has a binding affinity 42% that of estradiol. Analysis of [3-H]-I-Hex binding in rat uterine cytosol by sucrose density gradient centrifugation shows both an estrogen-specific binding component (8 S) and a more abundant component (4 S) that is not estrogen specific. Scatchard analysis indicates that this latter binding is of high affinity (Kd equals to 3.7-8.3 times 10- minus-9 M) but is not uterine specific. Polyacrylamide gel electrophoresis shows that most of the [3-H]-I-Hex binding activity in serum and uterine cytosol is distinct from and anodic to the principal protein component (albumin), and that is comigrates with [14-C]thyroxine binding activity. In in vitro incubation of rat uteri, I-Hex can block the specific uptake of [3-H]estradiol into the nuclear fraction; it itself causes a translocation of estrogen-specific binding capacity (as measured by exchange) from cytoplasm to nuclei, and can induce the synthesis of an estrogen-specific uterine protein, all under conditions where it is not metabolically deiodinated to hexestrol. The uterotrophic activities of the iodohexestrols are in most cases comparable to that expected on the basis of their competitive binding affinities. However, selective, estrogen-specific uptake of [3-H]-I-Hex into rat uterus, either in vitro or in vivo, cannot be demonstrated.

Animals↗
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

Antiestrogen action in the uterus: biological ineffectiveness of nuclear bound estradiol after antiestrogen.

These studies attempt to analyze the basis of the estrogenic and antiestrogenic action of three nonsteroidal clomophene-type compounds as monitored by their ability to bind to immature rat uterine cytoplasmic estrogen receptor, transfer receptor sites to the nucleus, and elicit estrogenic responses (increased uterine weight and induction of the synthesis of a specific uterine protein, called induced protein, or "IP"), and by their ability to antagonize the effects of estradiol on these receptor interactions and uterine responses. Both CI-628 (CI) and U-11, 100A (UA) [50 mug] elicit slight IP induction at 1-2 hand give pronounced uterine weight increases at 24 h but feeble increases at 72 h (3 single daily injections). Both bind to cytosol, and effect the transfer of receptor sites to the nucleus, which may account for the estrogenicity of these compounds. Both CI and UA give rapid (by 2-4 h), prolonged (for over 24 h), and complete blockage of estradiol-stimulated treatment abolishes short-term estradiol-stimulated uterine weight increase and antagonizes the 72 h estradiol-stimulated uterine weight response to the level attributable to the antiestrogen alone. MER-25, at the same dose (50 mug), had no estrogenic or antiestrogenic activity. Both CI and UA rapidly deplete the cytoplasmic estrogen binding capacity, reducing it to barely detectable levels for 24-42 h. Although during this period, no IP or uterine wet weight response can be elicited by estradiol, administration of saturating levels of [3H]estradiol in vivo or in vitro results in the appearance of considerable [3H]estradiol in the nucleus, bound to a macromolecule sedimenting identically with that of the nuclear receptor-estradiol complex (5.5S) formed in the absence of prior antiestrogen exposure. Hence, the estradiol which becomes bound in the nucleus after antiestrogen is biologically ineffective. The return of IP responsiveness after antiestrogen correlates well with the level of cytoplasmic receptor capable of translocation to the nucleus, and not with the nuclear estradiol uptake capacity, Presumably, then, the antiestrogenic action of CI and UA results from their depletion of cytoplasmic receptor sites and not from their ability to block specific estradiol-nuclear receptor binding per se. These studies indicate that one should be cautious in assuming that the magnitude of an estrogen response is necessarily related to the level of estrogen receptor complex in the nucleus.

Animals↗
PubMed1974

Uterine estrogen-induced protein: physical and immunological comparison with ovalbumin.

The physical and immunological properties of the estrogen-induced protein from rat uterus are compared with those of ovalbumin from chick oviduct. Both proteins are induced by estrogen and are under estrogenic regulation. Electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gels and elution behavior on Sephadex G-100 column chromatography indicate that the uterine protein has a molecular weight of about 42,000, similar to that of ovalbumin, and likewise is composed of only one subunit. On isoelectric focusing in polyacrylamide gels, both proteins focus at a pH of 4.6. The uterine protein, in addition, shows a component with an isoelectric point of 5.1. Despite considerable similarity in the physical properties of the uterine protein and ovalbumin, there is no significant crossreactivity of anti-ovalbumin gamma globulin with the uterine protein, implying that these two estrogen-regulated proteins are immunologically distinct.

Animals↗