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Estren Is a Selective Estrogen Receptor Modulator with Transcriptional Activity

Center for Bone Research at the Sahlgrenska Academy, Department of Internal Medicine, the Sahlgrenska Academy at Göteborg University, Göteborg, Sweden (S.M., N.A., U.I., H.C., C.O.); Karo Bio AB, Novum, Huddinge, Sweden (J.D., S.N.); and Department of Biosciences at Novum and Department of Medical Nutrition, Karolinska Institutet, Novum, Huddinge, Sweden (J.-Å.G.)

Received June 20, 2003; accepted September 4, 2003

	Abstract

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It was recently reported that the synthetic compound estren increases bone mass without affecting reproductive organs or classic transcription. The aim of the present study was to further characterize the in vivo and in vitro effects of estren. We demonstrate that estren is a selective estrogen receptor modulator (SERM) with a strong effect on thymus, a moderate effect on uterus and trabecular bone, but no major effect on fat or cortical bone in 11-month-old ovariectomized mice. The effect of estren on trabecular bone and uterus is mediated via estrogen receptors (ERs) because no effect is seen in ER double-inactivated mice. Furthermore, with the use of ER- and ER-expressing reporter cell lines, we demonstrate that estren displays an agonistic effect on transcriptional activity of an estrogen-responsive element-driven reporter gene with a degree of agonism similar to that of 17-estradiol for both ER and ER. Thus, estren has the capacity to exert genomic effects via both ER and ER. We conclude, in contrast to what was previously reported by others, that estren is a SERM with transcriptional activity.

	Materials and Methods

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Animals. Male and female double-heterozygous (ER^+/-+/-) mice were mated, resulting in WT, ER^-/-ER^+/+ (ER^-/-), ER^+/+ER^-/- (ER^-/-) and ER^-/-ER^-/- (ER^-/--/-) offspring with a mixed C57BL/6J/129 background (Lubahn et al., 1993; Krege et al., 1998). Genotyping of tail DNA was performed at 3 weeks of age as described previously (Vidal et al., 2000). Animals had free access to fresh water and soy-free food pellets (R70; Lactamin AB, Stockholm, Sweden). At 11 months of age, mice were ovariectomized (ovx) and injected daily subcutaneously with 17-estradiol benzoate (0.7 µg/mouse) (Sigma Chemical, St. Louis, MO) or estren (75 µg/mouse) (Steraloids, Newport, RI) for 4 weeks. Control mice received injections of vehicle oil (olive oil; Apoteksbolaget, Göteborg, Sweden).

Peripheral Quantitative Computerized Tomography. Computerized tomography was performed with the Stratec peripheral quantitative computerized tomography (pQCT) XCT Research M (version 5.4B; Norland Corporation, Fort Atkinson, WI) as described previously (Windahl et al., 1999). Trabecular bone mineral density (BMD) was determined ex vivo, with a metaphyseal pQCT scan of the proximal tibia and defined as the inner 45% of the total cross-sectional area. Cortical bone parameters were determined ex vivo with a mid-diaphyseal pQCT scan of the femur.

Generation of Stable ER and ER Reporter Cell Lines. Generation of stable human embryonic kidney 293 cells (American Type Culture Collection no. CRL 1573) expressing human ER and human ER and the pERE2-ALP reporter vector has been described previously (Barkhem et al., 1998). All cell lines were cultured routinely at 37°C in humidified chambers at 5% CO₂ in minimal essential medium (phenol red-free) supplemented with 10% FCS and 2 mM L-glutamine.

Assay Procedure for Hormonal Effects on 293/hER and 293/hER Reporter Cells. Cells (25 x 10³ per well) were seeded onto 96-well culture plates in 100 µl of Coon's/F12 (phenol red-free) supplemented with 10% FCS (stripped twice using dextran-coated charcoal) and 2 mM L-glutamine. Twenty-four hours later, conditioned medium was replaced with 100 µl Coon's/F12 supplemented with 1% FCS (stripped twice using dextran-coated charcoal), 2 mM L-glutamine, gentamicin (50 µg/ml), and hormonal substances as indicated in the figure legends. In all experiments, cells were exposed to hormones for 72 h before harvest and analysis for effect on reporter-gene expression. Triplicate determinations of reporter protein levels in the conditioned media for each concentration of compound were performed in all experiments.

Assay for Human Placental Alkaline Phosphatase. The level of alkaline phosphatase (ALP) expressed from the ERE2-ALP reporter vector in the stably transformed 293/hER and 293/hER reporter cells was determined using a chemiluminescent assay as follows: a 10-µl aliquot of heat-treated (at 65°C for 30 min) conditioned cell-culture medium was mixed with 200 µl of assay buffer (10 mM diethanolamine, pH 10.0, 1 mM MgCl₂, and 0.5 mM CSPD) in white microtiter plates (Dynatech Labs, Chantilly, VA) and incubated at 37°C for 20 min before being transferred to a microplate-format luminescence counter (1450 Microbeta; PerkinElmer Wallac, Turku, Finland). The setting of the Microbeta was for a 1-s reading of each well. The ALP activity is expressed in luminescence counts per second, which is directly proportional to the level of ALP expressed from the cells.

	Results

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Tissue Specificity for the Effect of Estren Compared with the Effect of 17-Estradiol. To determine the tissue specificity for the effect of estren compared with the effect of 17-estradiol, ovx mice were treated with vehicle, estren, or 17-estradiol (0.7 µg/mouse/day). Surprisingly, already at an estren dose of 75 µg/mouse/day, a clear effect was seen on the uterine weight (132 ± 28% over vehicle), which is in contrast to a previous study using a 70% higher dose of estren and demonstrating no uterine effect (Kousteni et al., 2002). The effects of estren on different estrogen-responsive tissues were then compared with the effects of a physiological dose of 17-estradiol (Lindberg et al., 2002). Both estren and 17-estradiol increased the uterine weight compared with vehicle in ovx mice (Fig. 1). The effect of estren on the uterine weight was 16% of the effect exerted by 17-estradiol (Table 1). As expected, the weights of the gonadal and the retroperitoneal fat deposits were reduced by 17-estradiol in ovx mice. In contrast, no effect on these fat deposits was seen by estren treatment (Fig. 2). It is well known that estrogen treatment decreases the weight of thymus (Marotti et al., 1984). Both 17-estradiol and estren treatment decreased the thymus weight, and for this parameter, the effects of estren and 17-estradiol were of the same magnitude (17-estradiol, -59 ± 11%; estren, -42 ± 6% compared with vehicle) (Table 1). Both estren and 17-estradiol increased the trabecular BMD, and the effect of estren on trabecular BMD was 22% of the effect exerted by 17-estradiol (Fig. 3A and Table 1). In contrast, cortical bone parameters, including cortical bone mineral content (BMC), cortical cross-sectional area, and cortical thickness, were increased by 17-estradiol but not by estren (Fig. 3B, Table 1, and data not shown).

View larger version (25K): [in this window] [in a new window]   Fig. 1. Weight of uterus. Eleven-month-old female WT and ER-/--/- mice were ovariectomized and then treated with vehicle, 17-estradiol (0.7 µg/mouse/day), or estren (75 µg/mouse/day) for 4 weeks (n = 7-8). Values given are means ± S.E.M. , p < 0.01, , p < 0.001 versus vehicle, Student's t test followed by post hoc analysis according to Bonferroni test.

View this table: [in this window] [in a new window]   TABLE 1 Tissue specificity for the effect of estren compared with the effect of 17-estradiol on uterine weight, gonadal fat weight, thymus weight, trabecular BMD, and cortical BMC Eleven-month-old female mice were ovariectomized and then treated for 4 weeks with vehicle, 17-estradiol, or estren (n = 8). Values for the effect of estren compared with the effect of 17-estradiol are given as the effect of estren divided by the effect of 17-estradiol and are expressed as a percentage (equal to the percentage of estrogenic activity of estren) and as the relative tissue specificity for the estrogenic activity of estren when the effect on uterus is given as 1 (equal to the relative tissue specificity of estren).

View larger version (26K): [in this window] [in a new window]   Fig. 2. Weight of gonadal (A) and retroperitoneal (B) fat deposits. Eleven-month-old female WT and ER-/--/- mice were ovariectomized and then treated with vehicle, 17-estradiol (0.7 µg/mouse/day), or estren (75 µg/mouse/day) for 4 weeks (n = 8). Values are given as means ± S.E.M. , p < 0.01, , p < 0.001 versus vehicle, Student's t test followed by post hoc analysis according to Bonferroni test.

View larger version (26K): [in this window] [in a new window]   Fig. 3. A, trabecular volumetric BMD of the metaphyseal area of the proximal tibia measured using pQCT. B, cortical BMC as determined using a mid-diaphyseal pQCT scan of the femur. Eleven-month-old female WT and ER-/--/- mice were ovariectomized and then treated with vehicle, 17-estradiol (0.7 µg/mouse/day), or estren (75 µg/mouse/day) for 4 weeks (n = 8). Values are given as means ± S.E.M. , p < 0.01, p < 0.05 versus vehicle, Student's t test followed by post hoc analysis according to Bonferroni test.

The Effects of Estren Are Mediated Via Estrogen Receptors. Because previous in vitro data have indicated that the effect of estren is mediated via ERs or the AR with similar efficiency (Kousteni et al., 2001, 2002), we designed an experiment to determine whether the in vivo effects of estren can be mediated via both the ERs and the AR. The in vivo effects of estren and 17-estradiol were investigated in WT and ER^-/--/- mice. The regulatory effects of estren and 17-estradiol on uterus, fat, trabecular bone, and cortical bone, observed in WT mice, were lost in ER^-/--/- mice (Figs. 1, 2, 3). Thus, the in vivo effects of estren and 17-estradiol on uterus weight and trabecular bone are mediated via ERs, and the AR cannot replace the ERs for the mediation of these effects (Figs. 1, 2, 3).

Estren has Transcriptional Activity. The in vivo experiments demonstrated that the effects of estren are mediated via ERs. To determine whether estren has any transcriptional activity mediated via ERs, the effect of estren on the activation of an estrogen-responsive element-driven reporter gene (ALP) was tested in vitro in human 293 kidney epithelial ER (293/hER)- and ER (293/hER)-expressing reporter cell lines (Barkhem et al., 1998). The responses of 293/hER and 293/hER to estren are shown in Fig. 4, A and B, and expressed as the percentage of agonism of 17-estradiol. Estren displayed a full agonistic effect on transcriptional activity with a degree of agonism similar to that of 17-estradiol for both receptors (99% agonistic activity via ER and 87% agonistic activity via ER compared with the activity of 17-estradiol) (Fig. 4, A and B). As expected from previous ER and ER binding studies (Kousteni et al., 2002), the transcriptional potency of estren was lower than that of 17-estradiol in both the 293/hER and the 293/hER cell lines (Fig. 4, A and B). The ER antagonist ICI 182,780 antagonized, in a dose-dependent manner, the effect of estren in both the 293/hER and the 293/hER cells. The potency of ICI 182,780 in antagonizing estren-induced gene expression was similar in both reporter cell lines (IC₅₀ values: 0.75 nM for ER and 0.57 nM for ER) (Fig. 4, C and D). Thus, estren is a full agonist for the transcriptional activity mediated via both ER and ER.

View larger version (22K): [in this window] [in a new window]   Fig. 4. Effect of estren and 17-estradiol on transcriptional activity. Response to increasing concentrations of 17-estradiol and estren in the 293/hER (A) and 293/hER (B) reporter cell lines. The level of ALP reporter protein expressed was analyzed 72 h after the addition of the ligands. Antagonist response to increasing concentration of ICI 182,780 in the presence or absence of estren (100 nM) in 293/hER (C) and 293/hER (D) reporter cell lines. The response values for each concentration of ligand are the means of triplicate determinations with the means ± S.D. for each value indicated.

	Discussion

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Estrogen replacement therapy is beneficial for the treatment of postmenopausal bone loss but is reported to have undesirable effects on reproductive tissue and is associated with an increased risk of breast cancer (Riggs and Hartmann, 2003). SERMs having the beneficial effects of estrogen in bone with reduced side effects in breast and uterus have been developed. However, currently available SERMs are less potent in bone than estrogen replacement therapy (Delmas et al., 1997). Therefore, the recent description of estren as a potent stimulator of bone mass and strength without any side effects on reproductive organs has been very much appreciated (Kousteni et al., 2001, 2002). Furthermore, the described mode of action for the bone-sparing effect of estren is unique because it was reported to be a nongenomic effect involving functional and direct interactions with components of the Src/Shc/extracellular signal-regulated kinase signaling pathways. Extranuclear signaling by classic ERs and AR is supported by numerous reports describing interactions between sex-steroid receptors and components of the intracellular signaling machinery including phosphatidylinositol-3-phosphate kinase, Src, and Shc (Migliaccio et al., 2000; Simoncini et al., 2000; Duan et al., 2001; Kousteni et al., 2001). The recently described extranuclear mode of action of estren in bone has led to the definition of a novel class of mechanism-specific substances called ANGELS (Activator of NonGenotropic Estrogen-Like Signaling) (Manolagas et al., 2002). However, the present study indicates that estren rather, in a wider perspective, is a SERM with transcriptional activity.

The results of our present characterization of the effects of estren are in conflict with two previous publications from one research group describing the in vitro and in vivo effects of estren (Kousteni et al., 2001, 2002). In the in vivo study by Kousteni et al., it was found that estren had no effect on the uterine weight, whereas in the present study, using even a slightly lower dose of estren than in the previous study, a clear estren-induced increase in uterine weight was seen. In agreement with the previous study, the amount of trabecular bone was increased by estren in the present study. However, in our study, the estrogen-like activity of estren was of the same magnitude on uterus as on trabecular bone, whereas in the previous study, a clear effect was seen on bone without any effect on uterus. It is difficult to explain the different results of the two studies. One may speculate that the 60-day slow-release treatment in the previous study was active during most of the time but not during the last few days of treatment. This would then result in bone, a slow-responding tissue, being preserved, with the uterus, a fast-responding tissue, no longer showing any effects of estren at the end of the treatment period. In contrast, in the present study, estren was given as subcutaneous daily injections during the whole experiment to ensure that the animals received the treatment until the final analysis.

In the present study, the effect of estren on several different tissues was investigated and compared with the effect of 17-estradiol. It was demonstrated that estren exerts a relatively strong effect on thymus weight, a medium effect on uterus weight and trabecular bone, and no effect on fat mass or cortical bone. Thus, the degree of the estrogen-like activity of estren is tissue-specific.

Previous in vitro data have indicated that the effect of estren might be mediated via ERs or the AR with similar efficiency (Kousteni et al., 2001, 2002). Here, we demonstrate in vivo that the effects of estren on trabecular bone and uterus are mediated via ERs and that the AR cannot replace the ERs in mediating these effects. We also demonstrate that the trabecular bone-sparing effect of 17-estradiol is mediated only via ERs and not via the AR. Furthermore, the bone-sparing effect of 5-dihydrotestosterone-induced AR stimulation is not dependent on the ERs (Movérare et al., 2003). Therefore, in contrast to what has recently been concluded from in vitro studies (Kousteni et al., 2001), there is no cross-reactivity between ERs and AR for the mediation of the trabecular bone-sparing effect of sex steroids, and the effect of estren in vivo is only mediated via ERs. Unfortunately, because of a complex breeding procedure of the ER-inactivated mice, no sham-operated control group was included in the present study. However, we have in a previous study seen that the 17-estradiol dose given to the ovx mice in the present study results in sham-operated control levels for the different estrogen-responsive parameters analyzed in the present study (data not shown).

Because of an in vitro finding that estren did not induce C3 transcription in ER-transfected HeLa cells, it was postulated that estren has no transcriptional activity and that all of its effects must be nongenomic (Kousteni et al., 2001). In contrast, using another well-established in vitro system of human 293 kidney epithelial ER- and ER-expressing reporter cell lines (Barkhem et al., 1998), we demonstrated that estren displays a full agonistic effect on transcriptional activity with a degree of agonism similar to that of 17-estradiol for both ER and ER. The specificity of this effect was confirmed by the result that the ER antagonist ICI 182,780 antagonized, in a dose-dependent manner, the effect of estren on the transcriptional activity mediated via both receptors. Thus, estren has the capacity to exert genomic effects via both ER and ER. In addition, we have also monitored the genomic response to estren in the human endometrial carcinoma cell line Ishikawa (Littlefield et al., 1990) by analyzing the expression of the endogenous alkaline phosphatase gene. Similar to the response in the genetically engineered 293 ER and ER reporter cell lines, estren generated an agonist response that was totally blunted by the pure ER antagonist ICI 182,780 (data not shown), supporting the notion that estren exerts ER-mediated genomic effects.

The conflicting results in the previous study using HeLa cells compared with the present study using 293 kidney epithelial cells might depend on the choice of promoter and/or the choice of cell line. It is well known that the effect of ERs is exclusively mediated via AF-2 in HeLa cells (Berry et al., 1990; Metivier et al., 2000), whereas in the 293 kidney epithelial cells, the activity of the ERs is dependent on the function of both AF-1 and AF-2. The lack of transcriptional activity of estren in HeLa cells might indicate that the agonist effect of estren on ERs requires functionality of both AF-1 and AF-2 (Berry et al., 1990; Metivier et al., 2000). We do not doubt that estren, in analogy to 17-estradiol, also elicits nongenomic responses, but our data clearly indicate, in contrast to the data from the study by Kousteni et al. (2002), that estren also has typical genomic effects. Thus, our data suggest that the biological effect of estren cannot solely be explained by a nongenomic mechanism but that genomic mechanisms of estren also have to be considered.

In conclusion, our results demonstrate that estren is a SERM with effects on uterus, trabecular bone, and thymus but without major effect on fat or cortical bone. The effects of estren on bone and uterus are mediated via ERs, and the AR cannot replace the ERs for these effects. Furthermore, it is clear that estren has the capacity to exert genomic effects mediated via ERs.

	Acknowledgements

 
We thank Anette Hansevi and Maud Petersson for excellent technical assistance. We also thank the SWEGENE Center for Bio-Imaging for technical support regarding image analysis.

	Footnotes

 
This study was supported by the Swedish Medical Research Council, the Swedish Foundation for Strategic Research, the European Commission grant QLK4-CT-2002-02528, the Lundberg Foundation, the Torsten and Ragnar Söderberg's Foundation, the Emil and Vera Cornell Foundation, Petrus and Augusta Hedlunds Foundation, the Swedish Cancer Fund, and Karo Bio AB.

ABBREVIATIONS: ER, estrogen receptor; ER, estrogen receptor ;ER, estrogen receptor ; SERM, selective estrogen receptor modulator; AR, androgen receptor; BMD, bone mineral density; BMC, bone mineral content; ovx, ovariectomized; WT, wild type; pQCT, peripheral quantitative computerized tomography; FCS, fetal calf serum; ALP, alkaline phosphatase; 293/hER, human 293 kidney cells expressing estrogen receptor ; 293/hER, human 293 kidney cells expressing estrogen receptor ; ICI 182,780, fulvestrant.

Address correspondence to: Dr. Claes Ohlsson, Department of Internal Medicine, Division of Endocrinology, Gröna Stråket 8, 413 45 Gothenburg, Sweden. E-mail: claes.ohlsson{at}medic.gu.se

	References

Top Abstract Materials and Methods Results Discussion References

 
Barkhem T, Carlsson B, Nilsson Y, Enmark E, Gustafsson J-Å, and Nilsson S (1998) Differential response of estrogen receptor and estrogen receptor to partial estrogen agonists/antagonists. Mol Pharmacol 54: 105-112.[Abstract/Free Full Text]

Berry M, Metzger D, and Chambon P (1990) Role of two activating domains of the oestrogen receptor in the cell-type and promoter-context dependent agonistic activity of the anti-oestrogen 4-hydroxytamoxifen. EMBO (Eur Mol Biol Organ) J 9: 2811-2818.[Medline]

Brubaker KD and Gay CV (1999) Evidence for plasma membrane-mediated effects of estrogen. Calcif Tissue Int 64: 459-462.[CrossRef][Medline]

Compston JE (2001) Sex steroids and bone. Physiol Rev 81: 419-447.[Abstract/Free Full Text]

Delmas PD, Bjarnason NH, Mitlak BH, Ravoux AC, Shah AS, Huster WJ, Draper M, and Christiansen C (1997) Effects of raloxifene on bone mineral density, serum cholesterol concentrations and uterine endometrium in postmenopausal women. N Engl J Med 337: 1641-1647.[Abstract/Free Full Text]

Duan R, Xie W, Burghardt RC, and Safe S (2001) Estrogen receptor-mediated activation of the serum response element in MCF-7 cells through MAPK-dependent phosphorylation of Elk-1. J Biol Chem 276: 11590-11598.[Abstract/Free Full Text]

Endoh H, Sasaki H, Maruyama K, Takeyama K, Waga I, Shimizu T, Kato S, and Kawashima H (1997) Rapid activation of MAP kinase by estrogen in the bone cell line. Biochem Biophys Res Commun 235: 99-102.[CrossRef][Medline]

Kousteni S, Bellido T, Plotkin LI, O'Brien CA, Bodenner DL, Han L, Han K, DiGregorio GB, Katzenellenbogen JA, Katzenellenbogen BS, et al. (2001) Nongenotropic, sex-nonspecific signaling through the estrogen or androgen receptors: dissociation from transcriptional activity. Cell 104: 719-730.[Medline]

Kousteni S, Chen JR, Bellido T, Han L, Ali AA, O'Brien CA, Plotkin L, Fu Q, Mancino AT, Wen Y, et al. (2002) Reversal of bone loss in mice by nongenotropic signaling of sex steroids. Science (Wash DC) 298: 843-846.[Abstract/Free Full Text]

Krege JH, Hodgin JB, Couse JF, Enmark E, Warner M, Mahler JF, Sar M, Korach KS, Gustafsson J-Å, and Smithies O (1998) Generation and reproductive phenotypes of mice lacking estrogen receptor beta. Proc Natl Acad Sci USA 95: 15677-15682.[Abstract/Free Full Text]

Lindberg MK, Moverare S, Skrtic S, Alatalo S, Halleen J, Mohan S, Gustafsson J-Å, and Ohlsson C (2002) Two different pathways for the maintenance of trabecular bone in adult male mice. J Bone Miner Res 17: 555-562.[CrossRef][Medline]

Littlefield BA, Gurpide E, Markiewicz L, McKinley B, and Hochberg RB (1990) A simple and sensitive microtiter plate estrogen bioassay based on stimulation of alkaline phosphatase in Ishikawa cells: estrogenic action of delta 5 adrenal steroids. Endocrinology 127: 2757-2762.[Abstract]

Lubahn DB, Moyer JS, Golding TS, Couse JF, Korach KS, and Smithies O (1993) Alteration of reproductive function but not prenatal sexual development after insertional disruption of the mouse estrogen receptor gene. Proc Natl Acad Sci USA 90: 11162-11166.[Abstract/Free Full Text]

Manolagas SC, Kousteni S, and Jilka RL (2002) Sex steroids and bone. Recent Prog Horm Res 57: 385-409.[Abstract/Free Full Text]

Marotti T, Sirotkovic M, Pavelic J, Gabrilovac J, and Pavelic K (1984) In vivo effect of progesteron and estrogen on thymus mass and T-cell functions in female mice. Horm Metab Res 16: 201-203.[Medline]

McEwen BS and Alves SE (1999) Estrogen actions in the central nervous system. Endocr Rev 20: 279-307.[Abstract/Free Full Text]

Metivier R, Petit FG, Valotaire Y, and Pakdel F (2000) Function of N-terminal transactivation domain of the estrogen receptor requires a potential alpha-helical structure and is negatively regulated by the A domain. Mol Endocrinol 14: 1849-1871.[Abstract/Free Full Text]

Migliaccio A, Castoria G, Di Domenico M, de Falco A, Bilancio A, Lombardi M, Barone MV, Ametrano D, Zannini MS, Abbondanza C, et al. (2000) Steroid-induced androgen receptor-oestradiol receptor beta-Src complex triggers prostate cancer cell proliferation. EMBO (Eur Mol Biol Organ) J 19: 5406-5417.[CrossRef][Medline]

Movérare S, Venken K, Eriksson A-L, Andersson N, Skrtic S, Wergedal J, Mohan S, Salmon P, Bouillon R, Gustafsson J-Å, et al. (2003) Differential effects on bone of estrogen receptor- and androgen receptor activation in orchidectomized adult male mice. Proc Natl Acad Sci USA In press.

Riggs BL and Hartmann LC (2003) Selective estrogen-receptor modulators—mechanisms of action and application to clinical practice. NEnglJMed 348: 618-629.[Free Full Text]

Simoncini T, Hafezi-Moghadam A, Brazil DP, Ley K, Chin WW, and Liao JK (2000) Interaction of oestrogen receptor with the regulatory subunit of phosphatidylinositol-3-OH kinase. Nature (Lond) 407: 538-541.[CrossRef][Medline]

Vidal O, Lindberg MK, Hollberg K, Baylink DJ, Andersson G, Lubahn DB, Mohan S, Gustafsson J-Å, and Ohlsson C (2000) Estrogen receptor specificity in the regulation of skeletal growth and maturation in male mice. Proc Natl Acad Sci USA 97: 5474-5479.[Abstract/Free Full Text]

Wehling M (1997) Specific, nongenomic actions of steroid hormones. Annu Rev Physiol 59: 365-393.[CrossRef][Medline]

Windahl SH, Vidal O, Andersson G, Gustafsson J-Å, and Ohlsson C (1999) Increased cortical bone mineral content but unchanged trabecular bone mineral density in female ERbeta(-/-) mice. J Clin Investig 104: 895-901.[Medline]

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