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At least 127 records · Page 7Linked to original sources

PubMed2001

Daily oral oleoyl-estrone gavage induces a dose-dependent loss of fat in Wistar rats.

OBJECTIVE: To establish whether single daily oral doses of oleoyl-estrone result in dose-dependent slimming effects on normal weight rats, and to determine the changes in energy parameters induced by this treatment. RESEARCH METHODS AND PROCEDURES: The effects of a daily oral gavage of oleoyl-estrone (0, 0.2, 0.5, 1, 2, 5, 10, and 20 micromol/kg per day) in 0.2 ml of sunflower oil given over a 10-day period were studied in groups, each of which contained six adult female Wistar rats initially weighing 190 to 230 g. A group of intact control rats receiving no gavage was included for comparison. Body weight and food intake were measured daily. Rats were killed on day 10 of treatment, and body composition (protein nitrogen, lipids, and water), liver lipids, and plasma parameters (glucose, triacylglycerols, total cholesterol, free fatty acids, 3-hydroxybutyrate, urea, aspartate, alanine transaminases, insulin, leptin, and free and acyl-estrone) were measured. RESULTS: The administration of oleoyl-estrone resulted in a dose-dependent loss of body fat, because of a partly maintained energy expenditure combined with decreased food intake. The differences in the energy budget were met by internal fat pools. The changes recorded did not affect the levels of the main plasma energy homeostasis indicators: unaltered glucose, triacylglycerols, free fatty acids, 3hydroxybutyrate, and urea. Protein was accrued even under conditions of severe lipid store drainage. There were no changes in transaminases. No lipid accumulation was recorded in the liver. Plasma insulin and leptin levels decreased with increased oleoyl-estrone doses, whereas the levels of free and esterified estrone increased with treatment, although not in proportion to the dose received. DISCUSSION: Oral treatment with oleoyl-estrone resulted in the specific dose-related loss of fat reserves with little change to other metabolic parameters. These results agree with the postulated role of oleoyl-estrone as a ponderostat signal.

Adipose Tissue↗

PubMed2006

Predominant contribution of organic anion transporting polypeptide OATP-B (OATP2B1) to apical uptake of estrone-3-sulfate by human intestinal Caco-2 cells.

Human organic anion transporting polypeptide OATP-B (OATP2B1) is a pH-sensitive transporter expressed in the apical membranes of small intestinal epithelial cells. In this study, we have examined the contribution of OATP-B to the uptake of [3H]estrone-3-sulfate in Caco-2 cells in comparison with those of its homologs OATP-D (OATP3A1) and OATP-E (OATP4A1). Immunocytochemical study revealed that OATP-B is expressed in the apical membranes of Caco-2 cells. The uptake of [3H]estrone-3-sulfate by Caco-2 cells was Na+-independent and inhibited by several organic anions. It showed biphasic saturation kinetics with Km values of 1.81 microM and 1.40 mM. The uptake of [3H]estrone-3-sulfate by human embryonic kidney (HEK) 293 cells stably expressing OATP-B (HEK293/OATP-B) was also Na+-independent and inhibited by several organic anions. The Km value for estrone-3-sulfate uptake by OATP-B (1.56 microM) was close to that for the high-affinity component observed in Caco-2 cells. The mRNA expression level of OATP-B was higher than that of OATP-D or OATP-E in Caco-2 cells and in human jejunum biopsies from healthy volunteers. The values of [3H]estrone-3-sulfate uptake normalized to OATP-B mRNA expression were similar in Caco-2 cells and HEK293/OATP-B cells. The specific activity of OATP-B per mRNA expression was much higher than that of OATP-D and OATP-E. [3H]Estrone-3-sulfate uptake by membrane vesicles prepared from HEK293/OATP-B cells exhibited an overshoot phenomenon in the presence of an inwardly directed H+ gradient, suggesting that an H+ gradient is the driving force of estrone-3-sulfate transport by OATP-B. These results suggest that OATP-B is predominantly responsible for the apical uptake of estrone-3-sulfate in Caco-2 cells.

Adult↗

PubMed1985

The effect of chronic and acyclic elevation of circulating androstenedione or estrone concentrations on ovarian function in the rhesus monkey.

The concept that chronically elevated blood androstenedione concentrations increase the incidence of anovulation in the primate and that acyclic elevated basal blood androgen and/or estrogen concentrations cause abnormal gonadotropin secretion was studied. Regularly menstruating female rhesus monkeys were implanted sc with Silastic tubing filled with androstenedione or estrone and compared with controls. Androstenedione implants increased the serum androstenedione concentrations from 1.6 +/- 0.1 (SE) ng/ml to 6.30 +/- 0.27 ng/ml. By peripheral conversion the testosterone concentration increased from control values of 279 +/- 10 (SE) pg/ml to 1280 +/- 41 pg/ml. The testosterone concentration in the estrone-treated monkeys was 247 +/- 9.7 pg/ml. The estrone concentrations were: controls, 63.2 +/- 3.1 (SE) pg/ml; androstenedione-treated monkeys, 63.2 +/- 3.1 pg/ml; and estrone-treated animals, 150 +/- 5.3 pg/ml. The corresponding estradiol concentrations were: control animals, 35.1 +/- 2.1 (SE) pg/ml; androstenedione animals, 30.9 +/- 1.8 pg/ml; and estrone-treated monkeys, 65.7 +/- 3.9 pg/ml. There was no difference in the morning serum cortisol concentrations between any of the three groups or between ovulatory or anovulatory months. The chronic elevation of either androstenedione or estrone caused an increased incidence of anovulation compared with the controls. Increased estrogen concentrations caused increased anovulation during both summer and winter months; however, increased androgen concentrations caused increased anovulation only during the summer months. However, LH concentrations were unaffected in either group but were lower during anovulation months in all three groups. An LH or FSH surge followed an estradiol bolus in three of four control animals and four of six androstenedione-treated but none of the estrone-treated monkeys. Histological examination of ovarian biopsies demonstrated thickening of the tunica albuginea ovarii in androgen-treated ovaries and an apparent increased number of atretic follicles. Corpora lutea were absent in the ovaries of the estrogen-treated monkeys, but otherwise these ovaries were similar to those of controls. It is concluded that chronic acyclic elevation of blood androstenedione (and resultant testosterone) increases seasonal anovulation in the rhesus monkey. Increased blood estrone (and resultant estradiol) leads to almost complete anovulation throughout the year and renders the central nervous system-pituitary axis insensitive to positive feedback effect of estradiol. Neither treatment caused an increase in basal LH concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Cortex↗

PubMed1978

A specific radioimmunoassay for estrone sulfate in plasma and urine without hydrolysis.

Estrone sulfate, quantitatively the most important estrogen in plasma, has previously been determined only after hydrolysis and chromatography. An antiserum raised against estrone glucosiduronate-bovine thyroglobulin was found to be suitable for the specific RIA of estrone sulfate both in plasma and urine. Plasma levels were measured after solvent extraction without hydrolysis or chromatography. The mean (+/-SE) was 972 +/- 79 pg/ml (range, 537-1581) in 15 women in the follicular phase, 1806 +/- 160 pg/ml (range, 814-3358) in 15 women in the luteal phase, and 922 +/- 62 pg/ml (range, 461-1238) in 13 men. The urinary excretion of estrone sulfate, measured after simple chromatographic separation, ranged from 0.8-7.9 micrograms/24 h in men and 5.1-18.7 micrograms/24h in nonpregnant women. This was generally one-seventh to one-half the simultaneous estrone glucosiduronate excretion rate. An approximate mean renal clearance of estrone sulfate calculated from the above values was 2.7 ml/min. The low clearance rate is taken to reflect extensive binding of estrone sulfate by plasma proteins. The splanchnic extraction of estrone sulfate measured in 6 patients undergoing hepatic vein catheterization for diagnostic purposes was 29.8 +/- 11.1%, indicating net uptake of this compound by the splanchnic area.

Antibody Specificity↗

PubMed1994

Effect of estrone treatment from day 30 to 45 of pregnancy on endometrial protein secretion and uterine capacity.

Secretion of proteins by the endometrium of pigs during pregnancy is reported to be influenced by progesterone and estrogen. The effect of estrone treatment from d 30 to 45 of pregnancy on endometrial protein secretion and uterine capacity was tested in unilaterally hysterectomized-ovariectomized (UHO) gilts. Ten intact and 16 UHO crossbred gilts were mated and assigned to the following treatments: 1) intact controls, n = 10; 2) UHO, n = 8; and 3) UHO + estrone (E; two 150-mg implants, 60-d release, implanted on d 30 of gestation), n = 8. Gilts were killed on d 45 of pregnancy. A sample of allantoic fluid was collected from each conceptus. Blood and endometrial tissue samples were collected to evaluate estrone concentrations, and placental and endometrial tissues were incubated to evaluate protein secretion. Estrone treatment increased (P < .01) plasma and endometrial tissue estrone concentrations. Unilateral hysterectomy-ovariectomy decreased (P < .01) fetal survival. No effect of estrone was detected on the number of live fetuses, protein secretion by endometrial tissue in culture, or allantoic fluid protein, acid phosphatase, retinol binding protein, or retinol. Estrone treatment decreased uterine weight (P = .05) and allantoic fluid fructose concentrations (P < .05). After correction for allantoic fluid volume, allantoic fluid protein, retinol, and acid phosphatase activity were decreased (P < .05) in UHO-treated pigs. The UHO treatment did not affect allantoic fluid fructose concentrations. These results indicate that 1) estrone treatment from d 30 to 45 of pregnancy and at the dosage used did not alter endometrial protein secretion or fetal survival, and 2) UHO decreased the amount of endometrial proteins available to conceptuses.

Acid Phosphatase↗

PubMed2004

Technical note: Measurement of total estrone content in foods. Application to dairy products.

Estrone is a powerful growth-inducing hormone that is present in milk, mainly in the form of fatty acid esters, at concentrations that promote growth in experimental animals. We present here a method useful for the measurement of this natural hormone in foods and applied it to several common dairy products. Samples were frozen, finely powdered, and lyophilized then extracted with trichloromethane/methanol; the dry extract was saponified with potassium hydroxide. The free estrone evolved was extracted with ethyl acetate and was used for the estimation of total estrone content through radioimmunoassay. Application of the method to dairy products showed high relative levels of total estrone (essentially acyl-estrone) in milk, in the range of 1 microM, which were halved in skimmed milk. Free estrone levels were much lower, in the nanomolar range. A large proportion of estrone esters was present in all other dairy products, fairly correlated with their fat content. The amount of estrone carried by milk is well within the range, where its intake may exert a physiological response in the sucklings for which it is provided. These growth-inducing and energy expenditure-lowering effects may affect humans ingesting significant amounts of dairy products.

Chloroform↗

PubMed1977

Membrane-bound estrone as substrate for microsomal UDP-glucuronyltransferase.

Nonpolar substrates of microsomal UDP-glucuronyl-transferase partition between the hydrophobic phase of the microsomal membrane and the bulk aqueous phase in a suspension of microsomes in water. Partitioning of estrone into the membranes was measured in the studies presented and was extensive. Comparison of the rate of conjugation of estrone and the rate of its release from microsomes into the bulk aqueous phase showed that the pool of estrone within the membrane is the substate for UDP-glucuronyl-transferase. The rate of conjugation of estrone was 6-fold greater than the rate of release of estrone from the membrane into the aqueous phase. Several additional experiments showed that the rate of glucuronidation of estrone did not depend on the amount of estrone in the bulk aqueous phase. It is concluded that the microsomal membrane serves to concentrate nonpolar substrates of UDP-glucuronly-transferase. The phospholipid region of the microsomal membrane also may be a co-factor of UDP-glucuronyltransferase in the sense that binding of estrone to the membrane restricts its orientation in a manner that facilitates catalysis.

Animals↗

PubMed1984

Estrone sulfatase activity in normal and abnormal endometrium.

We investigated the activity of estrone sulfatase in normal and pathological endometrium. In normal endometrium, the estrone sulfatase activity [pmol E1 X min-1 X (mg prot)-1] was 23.13 +/- 8.44 (mean +/- SD). An increase (p less than 0.01) of estrone sulfatase activity (62.81 +/- 21.97) was noted in mild endometrial hyperplasia. In focal hyperplasia (when the measurements were performed in the normal endometrial biopsies) such an increase was not noted (19.10 +/- 5.33). Estrone sulfatase activities of moderate hyperplasia (25.30 +/- 11.40) and endometrial neoplasia (30.30 +/- 9.57) were in the same range as in normal endometrium. Treatment with progestagen simultaneously reduced hyperplasia and estrone sulfatase activity. But when morphologically abnormal endometrium persisted after treatment, estrone sulfatase activity remained increased. The increase of estrone sulfatase activity appeared to be specific to mild endometrial hyperplasia. The role of estrone sulfatase in the pathogenesis of endometrial hyperplasia is discussed.

Adult↗

PubMed1993

Inhibition of estrone sulfatase and 17 beta-hydroxysteroid dehydrogenase by antiestrogens.

Circulating estrone sulfate levels are 10-fold higher than the free estrone and estradiol levels in postmenopausal women and could form a reservoir from which the free estrogens could be synthesized in situ in breast cancer tissues. The enzymes catalyzing conversion of estrone sulfate to free estrone and estradiol are estrone sulfatase and 17 beta-hydroxysteroid dehydrogenase, respectively. Selective blockade of these two enzymes may provide a means of reducing tumor estrogen levels and promoting tumor regression. The present study characterized the kinetics of several potential inhibitors of estrone sulfatase and 17 beta-hydroxysteroid dehydrogenase in vitro in rat breast tumors and compared these effects to those in human tissues. The antiestrogen ICI 164384 as well as tamoxifen and its metabolites inhibit estrone sulfatase via noncompetitive mechanisms at Kis ranging from 11-1130 microM in rat breast tumors. The steroid sulfates (pregnenolone sulfate and dehydroepiandrosterone sulfate) on the other hand, act as competitive inhibitors with Kis ranging from 4 to 6 microM. ICI 164384 and the tamoxifen metabolite 4-hydroxytamoxifen also blocked 17 beta-hydroxysteroid dehydrogenase at concentrations of 470 and 275 microM, respectively. In human breast tumors, 4-hydroxytamoxifen and desmethyltamoxifen blocked estrone sulfatase and 17 beta-hydroxysteroid dehydrogenase but at higher concentrations than in the rat (i.e. IC50s of 1000-2000 microM). The inhibition caused by the antiestrogens requires concentrations at least 100-fold higher than those necessary for antiestrogenic effects. Although blockade of enzyme action is significant in vitro, and could also be in vivo, the effects of antiestrogens on enzyme inhibition are likely to be outweighed by their ability to block estrogen receptor-mediated effects in patients.

17-Hydroxysteroid Dehydrogenases↗

PubMed1968

Metabolic clearance rates and interconversions of estrone and 17beta-estradiol in normal males and females.

The continuous infusion of (3)H-6,7-estrone and (3)H-6,7-estradiol has been used to study the metabolic clearance rate (MCR), the interconversions, and the red cell uptake of these steroids in normal males and females. The whole blood MCR of estrone is 1,990 +/- 120 liters per day/m(2) (SE) in males and 1,910 +/- 100 liters per day/m(2) in females. The whole blood MCR of estradiol is 1,600 +/- 80 liters per day/m(2) in males and 1,360 +/- 40 liters per day/m(2) in females. The values in females do not vary significantly when studied in the follicular or luteal phase of the cycle. At least 35% of the total estrone metabolism in both sexes is extrasplanchnic and at least 25% of the total estradiol metabolism in males, and 15% in females is extrasplanchnic. The [rho](BB) (2,1) [transfer constant of estradiol to estrone, which is equivalent to the fraction of the precursor (estradiol) converted to the product (estrone) when both the infusion of the precursor and the measurement of the product are in peripheral blood] is 15%; and the [rho](BB) (1,2) [transfer constant of estrone to estradiol, which is equivalent to the fraction of the precursor (estrone) converted to product (estradiol) when both the infusion of the precusor and the measurement of the product are in peripheral blood] is 5% in both males and females. Our findings concerning the radioactivity in whole blood, as measured by our procedure, were the following: 15-20% of estrone in both sexes and 15% of estradiol in males is associated with red cells. Only 2% of the whole blood radioactivity of estradiol in females is associated with red cells. Changes in the distribution of radioactivity between plasma and red cells will influence the MCR as calculated from plasma, but not as calculated from whole blood.

Journal Article↗

PubMed1984

Distribution of estrone sulfatase activity in the intestine of germfree and conventional rats.

The intestinal content, the mucosa and the rest of the intestinal wall of germfree (GF) and conventional ( CVL ) rats were tested for in vitro hydrolysis of [3H]estrone sulfate. In homogenates from GF rat intestine some estrone sulfate hydrolysis was detected in those from the proximal small intestine (PSI) (4.2 +/- 0.1% hydrolyzed after 4 h), but not in those from the distal small intestine (DSI) and the caecum. Estrone sulfate was also hydrolyzed by the homogenates of the mucosa and the rest of the intestinal wall from each of the segments tested (PSI: 12.8 +/- 0.4% (mucosa) and 21.5 +/- 2.1 (wall); DSI: 8.2 +/- 0.9% (mucosa) and 17.3 +/- 1.7% (wall); caecum: 8.8 +/- 1.6% (mucosa) and 17.3 +/- 0.5% (wall) ). In the homogenates of CVL rat intestine, the estrone sulfatase activity in the rest of the intestinal wall did not differ considerably from the values for GF rats, when expressed per mg protein of the homogenate. The mucosa of the CVL rats, however, showed higher rates of hydrolysis than the mucosa of the GF rats. The microbial estrone sulfatase activity in the intestinal content of CVL rats, tested by anaerobic incubation, was high in the caecum (91.7 +/- 6.6% after 4 h), but very low in the PSI (2.2 +/- 0.7%) and DSI (1.3 +/- 0.5%). Serial dilutions of the caecal content also showed higher viable numbers of estrone sulfate hydrolyzing bacteria. These results add further weight to the suggestion that estrone sulfate may be absorbed from the small intestine, but has to be hydrolyzed in the caecum by the gut microflora prior to absorption.

Anaerobiosis↗

PubMed1985

Excretion of total estrogens and estrone-3-glucuronide during treatment with human menopausal gonadotropins.

HMG treatment is usually monitored by the evaluation of the cervical mucus, the determination of plasma 17 beta-estradiol, total urinary estrogens, ultrasonographic evaluation or a combination of these. We evaluated the daily validity of estrone-3-glucuronide excretion in urine as an indicator of follicular growth and maturation in 28 infertile women who were treated with HMG (Pergonal 500). Total urinary estrogens and estrone-3-glucuronide were measured in 24 h urine collections, and 11 of the women collected the early-morning urine separately. This allowed comparison of the concentrations and excretion of total estrogens and estrone-3-glucuronide of the 24 h urine with that found in the urine collected overnight. This comparison was made on 83 urine samples. The correlation between either the total excretion per 24 h or the concentration per liter in the 24 h urine collection of the two systems of determination was good in all determinations. Also in the urine collected on the day prior to HCG administration, total estrogens measurement was in good correlation with the estrone-3-glucuronide. However, there was statistically a significant difference in the concentrations of total estrogens and estrone-3-glucuronide between the women who ovulated and those who did not. Estrone-3-glucuronide, when calculated as a percentage of the total estrogens, was 60.86% in the women who ovulated and 33.15% in those who did not. These results demonstrate that although estrone-3-glucuronide reflects ovarian function in women treated with HMG, it may serve as a better predictor to ovulation.

Chorionic Gonadotropin↗

PubMed1982

Sites of in vivo extraction and interconversion of estrone and estradiol in the dog.

The interconversion and extraction of estrone and estradiol-17beta across and within different tissues or areas have been studied in the dog by the constant infusion technique. The results were calculated estradiol obtained from afferent and efferent blood and tissues at equilibrium. From these results it is concluded that: (1) there is no significant difference between metabolic clearance rates of estrone and estradiol, (2) blood transfer constants indicates a higher conversion of estradiol to estrone than of estrone to estradiol, (3) the transtissue interconversion favors the formation of estrone while the intratissue interconversion favors the formation of estradiol, (4) no interconversion of the two estrogens is observed in adipose tissue, (5) the extraction of estradiol entering a tissue was lower than the extraction of estradiol formed in these tissues, (6) calculation of the tissue metabolic clearance rates show that 63% of the total metabolism of estrone and estradiol, respectively, occurs in the splanchnic bed, and (7) the contribution of each tissues to the total interconversion of estrone and estradiol show that more than 90% of this interconversion occurs extrahepatically.

Adipose Tissue↗

PubMed1995

A possible role of estrone produced in adipose tissues in modulating postmenopausal bone density.

Estrogen deficiency in postmenopausal women is a major contributing factor to bone loss occurring after menopause. Although serum estradiol levels decrease conspicuously, a considerable amount of estrone still exists in women after natural menopause. Since most of the estrone is converted from androgens in adipose tissues, we attempted to seek interrelationship among serum estrone levels, fat mass and bone mineral density (BMD) in postmenopausal women. Thirty women who underwent natural menopause at the age between 45 and 53 were examined for BMD of head, arms, trunk and legs, as well as total body fat and total lean body mass using a Lunar DPX, a dual energy X-ray absorptiometer. Serum estrone concentration in each subject was measured by RIA. BMD of all sites of bones examined showed a positive correlation with relative fat mass (total body fat/body weight). Serum estrone levels were positively correlated with BMD of arms, trunk and legs, as well as relative fat mass. Multiple regression analysis further demonstrated that relative fat mass and serum estrone levels were significantly related to BMD of both arms and trunk, and BMD of trunk, respectively. These results suggest that estrone produced in adipose tissues may have, if only in part, a role in modulating the loss of bone mass occurring after menopause.

Adipose Tissue↗

PubMed2006

Fatty acid esterification of lipoprotein-associated estrone in human plasma and follicular fluid.

Estrogen fatty acid esters constitute a unique family of extremely hydrophobic hormonal derivatives which are exclusively transported in lipoprotein particles in plasma. In estradiol, the fatty acyl residues are conjugated at the 17beta-hydroxyl of the steroid D-ring, leaving the phenolic 3-hydroxyl group unsubstituted and, therefore, preserving antioxidative efficacy. The 17beta-fatty acid derivative of estradiol is proposedly an even more efficient antioxidant protecting LDL and HDL than the parent steroid. Previous studies have established that the enzyme lecithin:cholesterol acyltransferase which catalyzes the fatty acid esterification of 3beta-hydroxyl group of cholesterol, also catalyzes the formation of estrogen 17beta-esters. Estrone, the principal estrogen in the postmenopausal female, has a keto group at carbon-17 and has been thought unable to form fatty acid esters. However, we detected hydrophobic derivatives of estrone following incubations with human plasma and ovarian follicular fluid. These derivatives accumulated in HDL and LDL during incubation showing chemical characteristics similar to estrone-3-fatty acid esters. Liquid chromatographic-mass spectrometric analyses established the presence of unhydrolyzed estrone esters consisting of different fatty acid species, the major one being estrone-3-linoleate, in human HDL particles following incubation of estrone with plasma. These extremely hydrophobic estrone conjugates could, in theory, represent a storage form of this estrogen.

Chromatography, Thin Layer↗

PubMed2003

[Weight loss in a patient with morbid obesity under treatment with oleoyl-estrone].

BACKGROUND AND OBJECTIVE: Oleoyl-estrone administration in rats results in loss of body fat and sparing protein via decreasing food intake and maintaining energy expenditure. Oleoyl-estrone also decreases insulin resistance and hyperlipidemia and has no direct estrogenic effects. Our objective was to determine whether oral oleoyl-estrone was effective in the treatment of morbid obesity in a voluntary patient. PATIENT AND METHOD: Oleoyl-estrone (150-300 mol/d) was given to a morbid obese man (BMI: 51.9) over 10 consecutive 21-day trial periods of oral drug intake followed by at least two months of recovery. This treatment was given without additional dietary restrictions. Plasma metabolites, hormones and enzymes were measured before treatment, during active administration and at recovery periods. RESULTS: Oleoyl-estrone decreased the body weight (38.5 kg in 27 months, final BMI: 40.5). No rebound trends were observed. No significant changes in blood parameters, plasma metabolites, hormones or enzymes were observed as a consequence of the treatment. CONCLUSIONS: Oleoyl-estrone decreased body weight in this subject without affecting metabolites or hormones, similarly to its effects in animal models. This means that oleoyl-estrone could have a marked potential as an anti-obesity drug.

Anti-Obesity Agents↗

PubMed1995

Inactivation of steroid sulfatase by an active site-directed inhibitor, estrone-3-O-sulfamate.

Steroid sulfatases are responsible for the hydrolysis of 3beta-hydroxy steroid sulfates, such as cholesterol and pregnenolone sulfate, and have an important role in regulating the synthesis of estrogenic steroids, from estrone sulfate and dehydroepiandrosterone sulfate, in endocrine-dependent tumors. Although little is known about the mechanism by which the sulfate group is removed from a steroid nucleus, an active site-directed sulfatase inhibitor has been developed. This inhibitor, estrone-3-O-sulfamate (EMATE), was synthesized by treating the sodium salt of estrone with sulfamoyl chloride. This compound inhibited not only estrone sulfatase but also dehydroepiandrosterone sulfatase activity in placental microsomes and in intact MCF-7 breast cancer cells. Pretreatment of MCF-7 cells or placental microsomes with EMATE, followed by extensive washing or dialysis indicated irreversible inhibition. This was confirmed by showing that EMATE inhibited estrone sulfatase activity in placental microsomes in a time-, concentration-, and pH-dependent manner. The enzyme is protected from inactivation by estrone sulfate, which is also consistent with active site-directed inhibition. EMATE is proposed to inactivate estrone sulfatase by irreversible sulfamoylation of the enzyme. Maximum enzyme activity was detected at pH 8.6, and the maximum rate of enzyme inactivation by EMATE also occurred at this pH. The pKa values of the enzymatic reaction and pKa of inactivation were 7.2 and 9.8, providing evidence that two active site residues are being modified by EMATE. As the phenolic pKa of tyrosine (9.7) and the pKa of histidine will allow the roles that (6.8) are similar to the pKa values of inactivation, these amino acid residues may play a role in the catalytic mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Arylsulfatases↗

PubMed2002

Effect of oral oleoyl-estrone treatment on plasma lipoproteins and tissue lipase activities of Zucker lean and obese female rats.

OBJECTIVE: To study the effect of oral oleoyl-estrone on the plasma lipoprotein profile and tissue lipase activities in order to determine the handling of circulating lipids by adipose tissue, liver and muscle of obese female rats. DESIGN: Lean (Fa/?) and obese (fa/fa) female Zucker rats treated for 10 days with a daily gavage of 0.2 ml sunflower oil containing 0 (controls) or 10 micromol/kg of oleoyl-estrone. After sacrifice, samples of tissues and plasma were taken. MEASUREMENTS: Plasma lipoprotein classes and composition; lipoprotein lipase and hepatic lipase activities in plasma, liver, skeletal muscle and periovaric and mesenteric white adipose tissue (WAT). RESULTS: Oleoyl-estrone decreased plasma cholesterol (mainly in HDLs: 76%) of lean rats, but dramatically decreased all lipid classes in obese rats, in which chylomicra and VLDL lost most of their triacylglycerols (95 and 81%, respectively). Hepatic lipase activity decreased markedly with oleoyl-estrone in all groups, both in plasma (79% lean, 100% obese) and liver (62% in both groups). Lipoprotein lipase activity was largely unchanged by oleoyl-estrone in lean rats, but in the obese it decreased in WAT (82% in periovaric, and 49% in mesenteric), and increased in plasma (x4) and in skeletal muscle (x5); liver levels showed no change. CONCLUSIONS: The shift observed in obese rats from a decrease in liver and WAT lipoprotein lipase and hepatic lipase activities to an increase in muscle lipoprotein lipase is coincident with the hypolipemic effect of oleoyl-estrone, especially in obese rats, and indicates that muscle is a key site for the disposal of endogenous fat mobilized due to oleoyl-estrone treatment.

Adipose Tissue↗