| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Endocrinology |
ERKO and ßERKO Mice1
Department of Urology, University of Illinois at Chicago, Chicago, Illinois 60612 [G. S. P., L. B.]; Receptor Biology Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709 [J. F. C., K. S. K.]; Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina 61801 [J. F. C.]; and Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 [I. C., B. K.]
 |
ABSTRACT |
|---|
 Top ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
within a subpopulation of stromal cells and ERß within epithelial cells, the present study was undertaken to determine the specific ER(s) involved in mediating prostatic developmental estrogenization. Wild-type (WT) mice, homozygous mutant ER (ERKO) -/- mice, and ßERKO -/- mice were injected with 2 µg of diethylstilbestrol (DES) or oil (controls) on days 1, 3, and 5 of life. Reproductive tracts were excised on days 5 or 10 (prepubertal), day 30 (pubertal), day 90 (young adult), or with aging at 6, 12, and 18 months of age. Prostate complexes were microdissected and examined histologically for prostatic lesions and markers of estrogenization. Immunocytochemistry was used to examine expression of androgen receptor, ER, ERß, cytokeratin 14 (basal cells), cytokeratin 18 (luminal cells), and dorsolateral protein over time in the treated mice. In WT-DES mice, developmental estrogenization of the prostate was observed at all of the time points as compared with WT-oil mice. These prostatic imprints included transient up-regulation of ER, down-regulation of androgen receptor, decreased ERß levels in adult prostate epithelium, lack of DLP secretory protein, and a continuous layer of basal cells lining the ducts. With aging, epithelial dysplasia and inflammatory cell infiltrate were observed in the ventral and dorsolateral prostate lobes. In contrast, the prostates of ERKO mice exhibited no response to neonatal DES either immediately after exposure or throughout life up to 18 months of age. Furthermore, neonatal DES treatment of ßERKO mice resulted in a prostatic response similar to that observed in WT animals. The present findings indicate that ER is the dominant ER form mediating the developmental estrogenization of the prostate gland. If epithelial ERß is involved in some component of estrogen imprinting, its role would be considered minor and would require the presence of ER expression in the prostatic stromal cells. |
INTRODUCTION |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
A fundamental understanding of developmental estrogenization of the prostate requires knowledge of the immediate cellular and molecular changes induced by estrogens that, in turn, alter the course of prostatic development long after the withdrawal of estrogens. Toward that end, we have characterized previously several immediate and long-term prostatic alterations induced by neonatal estrogen exposure in the rat prostate model. Exposure to high levels of estrogens during the developmental critical period (days 1–5) initially blocks epithelial cells from entering a normal differentiation pathway (3 , 20) resulting in permanent differentiation defects (7 , 21 , 22) . Histologically, early estrogen exposure suppresses the formation of the distal prostate and extends the proximal phenotype into a larger portion of the tissue (23) . The proximalized phenotype of the estrogenized prostate is characterized by a thick layer of periductal fibroblasts beneath the basement membrane and a continuous layer of basal epithelial cells between the basement membrane and the luminal cells (3 , 22) , which together may impede ductal branching and cell-cell interactions that are essential for normal morphogenesis. Because we have shown recently that neonatal estrogens alter hox-13 gene expression in the prostate (23) , we postulate that the effects of estrogen in creating a proximalized phenotype in the prostate gland may reflect a change in the positional identity of this structure, perhaps mediated by changes in the expression of distinct developmental genes.
The molecular mechanism whereby neonatal estrogen transmits its effects on the prostate gland is not completely understood. Although some of the effects of estrogen may be indirectly mediated through the hypothalamic-pituitary-testicular axis (24
, 25)
, a direct response at the level of the prostate has also been documented (6
, 26)
. Estrogen action is mediated through two distinct members of the nuclear steroid receptor gene superfamily, which possess high affinity for estrogenic ligands, namely, ER (27)
and ß (28)
. Both ER and ß are expressed in the rodent prostate gland; thus, either one or both ERs could potentially mediate the effects of estrogens on this tissue. In the normal developing rodent prostate, ER expression is confined to mesenchymal cells in the proximal region of the gland and is not present in the epithelial cells (29
, 30)
. Whereas ERß appears to be highly expressed in the epithelial cells of the adult prostate gland (28
, 31)
, its expression in the undifferentiated epithelium of the neonatal prostate is relatively low (32)
. The different cellular localization of ER and ß in the prostate gland is particularly significant because action through ER would imply a stromal-mediated estrogenization of the prostate, whereas action through ERß would indicate an epithelial cell pathway for the initiation of the estrogenized phenotype. Although neonatal exposure to estrogens does not initially alter ERß mRNA expression in the rat prostate (32)
, there is an immediate up-regulation of ER mRNA and protein within periductal stromal cells along the length of the developing ducts, which allows for amplification of estrogenic signals in these stromal cells (29)
. Evidence that this transiently up-regulated ER is functional comes from a concomitant, transient up-regulation of progesterone receptor, an estrogen regulated gene, in the same periductal cells (33)
. Whereas these findings implicate a specific role for ER in the developmental estrogenization of the prostate gland, it is nonetheless possible that ERß is also involved in this phenomenon.
The recent generation of transgenic mice with targeted deletion of the ER (ERKO; Refs. 34
, 35
) or the ERß (ßERKO) gene (36)
allows for the direct determination of the specific ER(s) involved in mediating the neonatal estrogen imprint on the prostate gland. In the present study, WT, ERKO and ßERKO mice were administered DES on postnatal days 1–5, and prostatic cellular and molecular markers for estrogenization were monitored from day 5 through 18 months of age. The WT mice given neonatal DES exhibited an estrogenized phenotype similar to that characterized previously for rats. We envisioned three potential outcomes for the knockout mice. The lack of a DES effect in ERKO mice lacking either ER or ß would implicate the involvement of that specific ER in mediating the estrogen effect. Conversely, developmental estrogenization after neonatal DES in an ERKO or ßERKO model would indicate the lack of involvement of that ER in estrogen imprinting. Alternatively, a partial DES effect in the ERKO models would suggest that both molecules may be involved in mediating estrogen action in the developing prostate. Our findings provide strong evidence that stromal ER is the dominant ER form mediating the effects of early estrogen exposure on the prostate gland.
|
MATERIALS AND METHODS |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
gene (ERKO) and the ERß gene (ßERKO) have been described previously (34
, 36)
. All of the mice for the present study were generated by breeding male and female mice heterozygous for the ER gene or the ERß gene to produce homozygous ER -/- (ERKO) or ERß -/- (ßERKO) null male offspring. Genotyping of tail DNA was accomplished using PCR with primers, which spanned the site of the disrupted gene as described previously (34
, 36)
. Pregnant mice were monitored for the day of delivery, which was considered day 0. Pups from each litter were randomly assigned to one of two treatment groups and administered either 2 µg of DES in corn oil or vehicle alone daily on postnatal days 1–5 via injection at the nape of the neck. Male mice were killed by decapitation on postnatal day 5 or 10 (prepubertal), day 30 (pubertal), day 90 (young adult), or at 6, 12, and 18 months of age (aged). Reproductive tracts were immediately removed by gross dissection, and the seminal vesicles were separated and weighed. The remainder of the reproductive tract was placed in Bouin’s fixative for 48 h and transferred to 70% ethanol. Under a dissecting microscope, the entire prostatic complex was microdissected from adjacent organs. After dehydration in increasing concentrations of ethanol and clearance in xylene, the prostate complex was embedded in paraffin along a singular axis to allow simultaneous sectioning through the ventral and dorsolateral lobes on a single tissue section. This approach allowed for orientation of the prostatic ducts relative to the urethral openings and, thus, verification of distal, central, and proximal duct location.
Immunocytochemistry.
Immunocytochemistry was performed according to methods published previously (37)
with modifications for paraffin-embedded tissues. Briefly, 4-µm paraffin sections were mounted on Superfrost Plus glass slides (Fisher Scientific, Itasca, IL) and heated at 37°C overnight. The sections were deparaffinized in xylene, gradually hydrated with decreasing concentrations of ethanol, and subjected to antigen retrieval. Slides were immersed in 0.1 M citrate buffer (pH 6.0; for AR, ER, CK14, CK18, and DLP2) or in 0.05 M glycine and 0.01% EDTA (pH 3.5; for ERß) and heated for 30 min in a Decloaking Chamber (Biocare Medical, Walnut Creek, CA). After a 10-min cooling period, the slides were slowly rinsed in running deionized water and endogenous peroxidases were removed with 3% H2O2 for 10 min. The slides were incubated with appropriate 2% blocking serum or SuperBlock blocking buffer (Pierce, Rockford, IL) for 30 min at room temperature and were subsequently incubated overnight at 4°C with primary antibody. The specific antibodies, sources, and concentrations used are presented in Table 1
. As a negative control, normal rabbit IgG (Vector Laboratories, Inc., Burlingame, CA) was substituted for primary antibody on separate sections of all of the tissues analyzed to determine nonspecific binding. The primary antibody was reacted with a species-appropriate biotinylated secondary antibody, and the biotin was detected with an avidin-biotin peroxidase kit (ABC-Elite; Vector Laboratories) using diaminobenzidine tetrachloride as a chromogen. As a final step, the sections were dehydrated gradually with alcohol, cleared with xylene, and coverslipped with Permount (Fisher Scientific). Some sections were stained with Gill’s #3 hematoxylin (1:4) as a blue nuclear counterstain. In addition to immunocytochemistry, sections from all of the time points and treatment groups were stained with H&E using standard technique to allow for examination of histological details.
|
ERKO, and ßERKO mice were always run in the same immunocytochemical assay to reduce discrepancies related to interassay variability in staining intensity. In many instances, the oil control prostate and the DES-exposed prostate from a given genotype and time point were processed on the same glass slide to allow for direct comparison of immunostain intensity between treatment groups. Images were digitally obtained with a Spot RT camera (Diagnostic Instruments, Inc.) attached to a Nikon E-400 microscope using a x40 objective and ImagePro software. Photographic plates were assembled with Adobe PhotoShop software.
Statistical Analysis.
All of the data sets were first tested for homoscedasticity of variance using the Levine’s test. In cases where data were found to lack homoscedasticity of variance, all of the data were log-transformed before additional statistical analysis. In all of the cases, data sets were analyzed by one-way ANOVA followed by individual post-hoc comparisons. Statistical analysis was carried out using the interactive statistical internet websites of the physics department of the College of Saint Benedict/St. Johns University4
and GraphPad5
.
|
RESULTS |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
ERKO males to serve as a surrogate marker for neonatal DES effects on accessory sex gland growth. Previous studies have shown that similar to the prostate, the seminal vesicles are sensitive to high-dose neonatal estrogen exposures (39
, 40)
. Fig. 1
shows the effects of neonatal DES treatment on seminal vesicle size in WT and ERKO mice at 4, 8, 12, and 18 months of age. At all ages, neonatal exposure of WT mice to 2 µg of DES on days 1–5 resulted in a significant reduction in seminal vesicle size as compared with oil-treated counterparts. In contrast, there was no difference in seminal vesicle weights between DES and oil-treated ERKO mice at each time point. It was observed that the seminal vesicles of ERKO mice exhibited a marked age-related increase in size as compared with WT males at each time point. This sustained seminal vesicle growth over time is thought to be a result of elevated circulating testosterone levels present in the ERKO male mice as compared with the WT animals (35)
.
|
presents representative histology sections of ventral and dorsolateral prostates of aged WT, ERKO, and ßERKO mice that had been neonatally treated with oil or 2 µg of DES on days 1–5 of life. The ventral prostate ducts of WT mice at 6 months and 1 year of age are characterized by a single cell layer of cuboidal to low columnar epithelial cells in the central ductal regions (Fig. 2, A and E)
with infolding of this epithelial layer in the distal tips. The dorsolateral prostates of WT mice contain acini with marked infolding of the single-cell epithelial layer, which produces a complex-appearing structure throughout a typical cross-section of the tissue (Fig. 2, C and G)
. Neonatal exposure to DES resulted in significant histological alterations in the aged ventral and dorsolateral prostates of WT mice, which include a relative increase in stromal mass, large pockets of interstitial lymphocytic infiltrate, marked epithelial cell hyperplasia, and dysplasia characterized by nuclear enlargement, variable nuclear size, and hyperchromasia (Fig. 2, B, D, F, and H)
. The severity of these prostatic lesions increased with age in the WT animals and were most severe at 18 months of age. Unlike the rat prostate where lobe-specific differences were observed, the ventral and dorsolateral lobes appeared equally affected by neonatal estrogen exposure in the WT mice.
|
ERKO mice appeared histologically identical to WT oil-control prostates at all of the time points including 1 year of age (Fig. 2, I and K)
. In contrast to the WT mice, neonatal exposure to DES had no effect on the histological appearance of the aged ventral or dorsolateral lobes in ERKO mice (Fig. 2, J and L)
. Prostates from oil-treated ßERKO mice also appeared similar to oil-control WT and ERKO mice at 6 months of age with no evidence of epithelial hyperplasia when similar regions of the ducts and lobes were directly compared (Fig. 2, M and O)
. However, in contrast to the ERKO mice, prostates from ßERKO mice neonatally exposed to DES exhibited all of the histological identifiers of an estrogenized prostate including increased stromal cells, lymphocytic infiltrate, epithelial hyperplasia, and dysplastic foci at 6 months of age (Fig. 2, N and P)
. One noted difference was that the dorsolateral prostate of ßERKO mice appeared consistently more affected than the ventral lobe.
Epithelial Cell Differentiation.
To better characterize differentiation defects induced by neonatal estrogen exposure and to determine the comparative extent of the DES effect in the different ERKO models, differentiation markers were used histochemically to identify basal cells (CK14), luminal cells (CK18) and DLP, the major secretory product of the mouse dorsolateral prostate and a marker of functional differentiation. The typical prostate of the adult WT mouse contains a limited number of basal epithelial cells, which are intermittently located along the basement membrane (Fig. 3A
, arrowheads), differentiated luminal epithelial cells, which line the ducts in a single cell layer (Fig. 3B)
, and strong epithelial DLP stain in the dorsolateral prostate (Fig. 3C)
. Neonatal exposure to DES resulted in prostates with epithelial ducts and acini lined by a continuous layer of basal cells (Fig. 3D)
, extensive piling and hyperplasia of luminal cells (Fig. 3E
, arrows), and loss of DLP expression in the dorsolateral lobe (Fig. 3F)
. In addition, a thick periductal layer of stromal cells was apparent along the lengths of the ducts (Fig. 3E
, arrowheads). These hallmark indicators of estrogen imprinting were not evident in the ERKO mice where both oil and DES-treated prostates contained few basal cells (Fig. 2, G and J
, arrows), a single cell layer of luminal cells (Fig. 3, H and K)
, and strong immunostain for DLP in the dorsolateral lobe (Fig. 3, I and L)
. Ventral prostates from day 90 oil-control ßERKO mice were similar to wild type and ERKO controls with occasional basal cells (Fig. 3M
, arrow) and a single cell layer of differentiated luminal cells (Fig. 3N)
. Similarly, the day 90 dorsolateral prostate was strongly stained for DLP protein (Fig. 3O)
. Neonatal exposure of ßERKO mice to DES resulted in estrogen imprinting of prostatic epithelial differentiation as characterized by a continuous layer of basal cells along the basement membrane (Fig. 3P)
, extensive hyperplasia of the luminal cells (Fig. 3 P–R
, arrowheads), stromal lymphocytic infiltrate (Fig. 3, P and Q
, arrows), and loss of DLP expression in the dorsolateral prostate (Fig. 3R)
. Also notable in the estrogen-exposed day 10 ßERKO prostate was a thick periductal layer of fibroblasts and smooth muscle cells along the ductal length, which is an early marker of the estrogenized proximal phenotype (Fig. 4J
, arrowheads).
|
|
ERKO, and ßERKO mice. At day 10, AR is strongly localized to the nucleus of periductal smooth muscle cells, whereas the epithelial cells stain at a moderate staining intensity in the WT mouse prostate (Fig. 4A)
. Treatment with DES from days 1 to 5 eliminated epithelial AR and severely reduced stromal cell AR labeling to a low stain intensity at day 10 (Fig. 4B)
. In the day 90 (adult) WT mouse prostate, epithelial cell nuclei and periductal smooth muscle cells were strongly AR-positive in oil-treated prostates (Fig. 4C)
, and AR down-regulation attributable to neonatal DES treatment persisted (Fig. 4D)
. AR immunostain profiles in the oil-control ERKO mice were indistinguishable from WT prostates at both day 10 and day 90 (Fig. 4, E and G)
, and neonatal exposure of ERKO mice to DES had no effect on prostatic AR expression in the developing or the adult prostate gland (Fig. 4, F and H)
. The day 10 and adult prostates of oil-treated ßERKO mice expressed AR within stromal and epithelial cells similar to the WT animals (Fig. 4, I and K)
. Neonatal exposure of ßERKO mice to DES resulted in a loss of epithelial AR immunostain and reduced periductal smooth muscle AR at day 10 (Fig. 4J)
. In contrast to the WT mice, adult prostates of ßERKO mice exposed to neonatal DES contained normal amounts of AR within ventral lobe epithelial cells (Fig. 4L)
, whereas dorsolateral lobes were AR negative.
ERs.
Earlier studies with rat prostate demonstrated that ER immunolocalized to a subset of mesenchymal cells in the proximal aspects of the developing prostate lobes, and this was up-regulated in a transient manner after neonatal exposure to estrogens (29)
. To determine whether similar autoregulation of ER takes place in estrogenized mice, we immunostained for ER in prostates of day 5 and 10 WT, ERKO, and ßERKO mice. At day 5, ER localized to a small number of mesenchymal cells in the proximal aspect of the ventral and dorsolateral prostate in the WT mice (Fig. 5A)
. Similar to rats, mesenchymal ER was markedly up-regulated by neonatal DES exposure (Fig. 5B)
. This autoregulation of ER was transient, because by day 30, prostates from WT DES-treated mice contained few ER-positive cells. Similar to the WT prostate, ER localized to the periductal stromal cells in the proximal prostatic region of day 10 ßERKO mice (Fig. 5C)
. After DES treatment from days 1 to 5, the number of periductal stromal cells positive for ER was greater in the ßERKO mouse prostate as compared with oil controls (Fig. 5D)
. As expected, there was no specific ER immunostain in the ERKO mouse prostate (Fig. 5E)
. It is important to note that ER immunostain was not observed in the epithelial cells of the ventral or dorsolateral lobes in any of the mice in this study.
|
. Similarly, using the same conditions that provided positive results in the adult mouse prostate and ovary, we found no detectable ERß protein in the neonatal prostate of WT mice treated with oil or DES (Fig. 5, G and H)
. In contrast, nuclear immunostain was present at moderate-to-strong stain intensity within the luminal epithelial cells of the adult WT mouse ventral and dorsolateral prostate lobes (Fig. 5I)
. Treatment of WT mice with neonatal DES resulted in a significant reduction of nuclear ERß throughout the epithelium of all prostate regions in the adult animals (Fig. 5J)
. In adult ERKO mice, ERß staining and localization was similar to the WT mouse (Fig. 5K)
indicating that ER is not required for normal ERß expression within the prostate. However, in contrast to the WT mice, the ventral and dorsolateral prostates from DES-treated ERKO mice also exhibited strong nuclear immunostain for ERß (Fig. 5L)
. As expected, there was no ERß immunostain in the adult ßERKO mouse prostate glands with the use of the CFK-E12 antibody. |
DISCUSSION |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
is the dominant ER mediating developmental estrogenization of the rodent prostate gland after neonatal exposure to estrogens. The prostate glands of the WT C57BL/6J/129 black mice used in the present study exhibited all of the hallmarks of neonatal estrogen imprinting that have been characterized previously by this laboratory in the rat model as well as by others in different mouse strains (9
, 11
, 43)
. These features included a disruption in epithelial cell differentiation as evidenced by loss of its major secretory product as well as a proximalized phenotype characterized by an increased thickness of periductal stromal cells and a continuous layer of basal cells along the length of the ducts. Additionally, adult seminal vesicle weights were markedly smaller in estrogenized mice indicating that accessory sex gland growth was affected. Pathological sequella of neonatal estrogen exposure were evident in the adult WT mouse prostate and included extensive hyperplasia of the epithelium in the young adult, progression to epithelial dysplasia with aging, and severe inflammatory cell infiltrate. Similar to previous findings in the rat model (3
, 6
, 32)
, neonatal estrogens induced a down-regulation in epithelial cell AR and ERß, which, themselves, are considered markers of a differentiated prostatic epithelium. Thus, it is reasonable to assume that similar molecular pathways are mediating the developmental estrogenization of the prostate in both the rat and the mouse and that these responses are fully present in the C57BL/6J/129 black strain used to generate the knockout mice. Using this extensive panel of markers for developmental estrogenization of the prostate, we observed no evidence of estrogen imprinting in the ERKO mice either immediately after the estrogenic exposure (days 5–10) or throughout life up to 18 months of age. In contrast, the ßERKO mice exhibited estrogenization of the prostate gland in response to estrogenic exposure with both early effects on stromal cells, AR and ER levels at day 10, and progressive epithelial and immune cell pathology with aging. Thus, these combined results indicate that, whereas ER is essential, the presence of ERß is not required for the mediation of estrogen imprinting in the developing prostate gland. A similar conclusion was reached concerning the adult prostatic response to 3 weeks of DES treatment where squamous metaplasia is induced in WT and ßERKO mice but not in the prostates of ERKO animals (44)
. Thus, it appears that in both the developing and the adult prostate gland, estrogenic responses that lead to prostatic lesions are mediated through the ER.
ERß protein was undetectable by immunocytochemistry in the developing prostate glands of WT and ERKO mice, and treatment with DES between days 1 and 5 did not induce its expression at that time. Thus, unlike ER (29)
, ERß does not appear to be directly autoregulated by estrogen in the developing mouse prostate. Previous work with the neonatal rat prostate had shown the presence of ERß mRNA in mesenchymal and undifferentiated epithelial cells at day 5 of life; however, the levels were extremely low in comparison with expression observed in the adult prostate epithelium (32)
. It is possible that either this low mRNA level is not translated at that time or that the translation product is below the limit of detection by histochemistry. Strong nuclear stain for ERß was observed in adult prostatic epithelial cells in both WT as well as ERKO mice, which confirms previous reports that ERß expression does not require ER in reproductive tissues (45)
. In the adult WT mice treated neonatally with DES, a marked reduction in nuclear ERß immunostain was observed in both the ventral and dorsolateral prostate lobes. Importantly, this effect was absent in the ERKO adult prostate of DES-exposed mice, which indicates that ERß down-regulation is likely to be the result of events initiated through ER in the neonatal prostate. These findings are similar to what we observed previously in the neonatally estrogenized ventral prostate of the Sprague Dawley rat (32)
. There, ERß mRNA levels were not initially autoregulated by neonatal estradiol; however, they failed to exhibit the differentiation-associated increase in epithelial expression between days 10 and 90. At day 90, estrogenized rat ventral lobes contained little ERß mRNA, whereas in the dorsal and lateral lobes, strong signal was observed in the epithelium. It is important to note that unlike the present findings in the WT mouse prostate where the lobes were equally effected by estrogen, in the rat model, neonatal estrogen exposure results in a lobe-specific effect where the ventral lobe is highly estrogenized, the dorsal lobe shows a reduced effect, and the lateral lobe exhibits normal epithelial cell differentiation (6)
. Thus, ERß expression directly correlates with differentiation status in the rat prostate epithelium. Together with the present findings, we hypothesize that ERß in the rodent prostate is a marker of a differentiated epithelial cell, and loss of ERß expression in the estrogenized prostate is a result of differentiation defects in the epithelium. Alternatively, it could be argued that it is the lack of normal ERß expression in the epithelial cells after neonatal estrogenization that leads to the differentiation defects and, eventually, the adult onset of hyperplasia and dysplasia, which progress with aging. However, the presence of normally differentiated epithelial cells in the adult ßERKO mice as evidenced both morphologically and by the presence of DLP secretory protein with no signs of prostatic hyperplasia and dysplasia with aging suggests that ERß is not required for epithelial differentiation and argues against that explanation. Nonetheless, it remains possible that lack of functional ERß in the adult prostate of estrogenized rodents contributes to the progression of prostatic dysplasia initiated through ER during the neonatal period.
Similar to the WT mice, neonatal DES exposure of ßERKO mice resulted in marked suppression of AR immunostain in prostatic epithelial and stromal cells at day 10. This effect is apparently mediated through ER, because AR down-regulation does not occur in the ERKO mouse prostate after estrogen exposure on days 1–5. One noticeable difference between the estrogenized WT and ßERKO mouse prostates was the transient nature of AR down-regulation in the ßERKO prostates, because strong AR expression was observed within adult ventral lobe epithelial cells of neonatally estrogenized ßERKO mice. We have hypothesized previously that estrogenization is attributable, in part, to loss of prostatic AR during the critical developmental window, and the present findings would continue to support that theory. However, the presence of AR in the adult ventral prostate epithelium of estrogenized ßERKO mice could indicate that continued down-regulation of AR expression is not required for the progressive pathology, which occurs with aging in the estrogenized prostate gland. The mechanistic basis for continued AR expression in neonatally estrogenized adult prostates that lack ERß is presently unclear. Although not quantitated in the present study, it was consistently noted that AR immunostain was stronger in the oil-control ßERKO ventral prostate epithelial cells as compared with those in WT mice. The present findings support the proposal that ERß may be involved in some component of AR regulation in prostate epithelial cells. Nonetheless, it is important to note that AR is down-regulated in the adult WT mouse prostate in response to neonatal DES despite the loss of epithelial ERß in the adult prostate gland. Thus, results from this treatment suggest that the presence of ERß appears not to be a requirement for DES-induced AR suppression in the prostate.
In both the WT and ßERKO mice, where developmental estrogenization of the prostate occurred, there was a transient up-regulation of ER within periductal stromal cells, which allows for the amplification of estrogenic signals within that target population. ER was not observed in the prostate epithelial cells of any of the mice in the present study, which confirms our previous observation in the rat prostate lobes (29)
as well as RT-PCR analysis of the separate rat lobes where ER mRNA was undetectable in the prostatic epithelial cells (31)
. Taken together with the lack of estrogenization in the ERKO model, these findings implicate the involvement of stromal-derived paracrine factors regulated by stromal ER in mediating the estrogen imprint of the prostate epithelium. This contrasts with a recent study involving stromal-epithelial recombination techniques with tissues from WT and ERKO mice where it was concluded that ER in both the epithelial and stromal fractions were required for estrogen induction of prostatic squamous metaplasia (44)
. However, in that study, epithelium was obtained from the adult anterior prostate (coagulating gland), which expresses epithelial ER in the WT uninduced state in contrast with prostate lobes of which the epithelium are ER negative. Additionally, the stromal component of the tissue recombinants was derived from seminal vesicle mesenchyme. Mesenchyme is a potent inducer of epithelial cell gene expression in a tissue-specific manner (46)
and, unlike the prostate, seminal vesicle epithelium expresses ER (47)
. Embryologically, the prostate gland is of urogenital sinus or endodermal origin, the seminal vesicle is of Wolffian duct or mesodermal origin, and the coagulating gland is a hybrid gland derived from urogenital sinus epithelium penetrating into seminal vesicle (Wolffian duct) mesenchyme. Thus, it is possible that the seminal vesicle mesenchyme is involved in the induction of ER expression within epithelial cells. These differences in the embryological origin of the tissues used in that recombinant study and the natural associated prostate tissue examined in present study, as well as the ability of the coagulating gland epithelium to express ER may explain our divergent conclusions.
In conclusion, the present study demonstrates that developmental estrogenization of the prostate gland is mediated through ER present within periductal stromal cells of the developing gland, which indicates that epithelial defects are initiated through a paracrine mechanism. If epithelial ERß is involved in some component of prostatic estrogen imprinting, its role would be considered minor, and it appears to require the presence of ER within the developing gland.
|
FOOTNOTES |
|---|
1 Supported by NIH Grants DK-40890, CA-18119, and Environmental Protection Agency STAR GR826299. 
2 To whom requests for reprints should be addressed, at Department of Urology, University of Illinois at Chicago, M/C 955, Chicago, IL 60612. E-mail: gprins{at}uic.edu
3 The abbreviations used are: DES, diethylstilbestrol; ER, estrogen receptor; WT, wild-type; ERKO, homozygous mutant estrogen receptor; AR, androgen receptor; DLP, dorsolateral protein; CK, cytokeratin.
4 http://www.physics.csbsju.edu.
6 I. Choi, C. Ko, O-K. Park-Sarge, R. Nie, R. Hess, C. Graves, and B. S. Katzenellenbogen. Human estrogen receptor ß-specific monoclonal antibodies: characterization and use in studies of estrogen receptor ß protein expression in reproductive tissues, in press.
Received 3/ 6/01. Accepted 6/11/01.
|
REFERENCES |
|---|
|
TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
and -ß, and progesterone receptor mRNA expression in various prostatic lobes and microdissected normal and dysplastic epithelial tissues of the Noble rats. Endocrinology, 139: 424-427, 1998. mediates effects of estrogen on prostatic epithelium. Dev. Biol., 229: 432-444, 2001.[Medline]
(ER) and estrogen receptor-ß (ERß) messenger ribonucleic acid in the wild-type and ER-knockout mouse. Endocrinology, 138: 4613-4621, 1997.This article has been cited by other articles:
|
|
 |
|
  J. Ahn, F. R. Schumacher, S. I. Berndt, R. Pfeiffer, D. Albanes, G. L. Andriole, E. Ardanaz, H. Boeing, B. Bueno-de-Mesquita, S. J. Chanock, et al. Quantitative trait loci predicting circulating sex steroid hormones in men from the NCI-Breast and Prostate Cancer Cohort Consortium (BPC3) Hum. Mol. Genet., October 1, 2009; 18(19): 3749 - 3757. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. J. Ellem, H. Wang, M. Poutanen, and G. P. Risbridger Increased Endogenous Estrogen Synthesis Leads to the Sequential Induction of Prostatic Inflammation (Prostatitis) and Prostatic Pre-Malignancy Am. J. Pathol., September 1, 2009; 175(3): 1187 - 1199. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Nicolaiew, G. Cancel-Tassin, A. R. Azzouzi, B. L. Grand, P. Mangin, L. Cormier, G. Fournier, J.-P. Giordanella, M. Pouchard, J.-L. Escary, et al. Association between estrogen and androgen receptor genes and prostate cancer risk Eur. J. Endocrinol., January 1, 2009; 160(1): 101 - 106. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Chen, I. Hsu, A. Wolfe, S. Radovick, K. Huang, S. Yu, C. Chang, E. M. Messing, and S. Yeh Defects of Prostate Development and Reproductive System in the Estrogen Receptor-{alpha} Null Male Mice Endocrinology, January 1, 2009; 150(1): 251 - 259. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S.-H. Chung, K. Wiedmeyer, A. Shai, K. S. Korach, and P. F. Lambert Requirement for Estrogen Receptor {alpha} in a Mouse Model for Human Papillomavirus-Associated Cervical Cancer Cancer Res., December 1, 2008; 68(23): 9928 - 9934. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Smith, D. Sepkovic, H. L. Bradlow, and K. J. Auborn 3,3'-Diindolylmethane and Genistein Decrease the Adverse Effects of Estrogen in LNCaP and PC-3 Prostate Cancer Cells J. Nutr., December 1, 2008; 138(12): 2379 - 2385. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Omoto Estrogen Receptor-{alpha} Signaling in Growth of the Ventral Prostate: Comparison of Neonatal Growth and Postcastration Regrowth Endocrinology, September 1, 2008; 149(9): 4421 - 4427. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. A. Ricke, S. J. McPherson, J. J. Bianco, G. R. Cunha, Y. Wang, and G. P. Risbridger Prostatic hormonal carcinogenesis is mediated by in situ estrogen production and estrogen receptor alpha signaling FASEB J, May 1, 2008; 22(5): 1512 - 1520. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. A. Albertelli, O. A. O'Mahony, M. Brogley, J. Tosoian, M. Steinkamp, S. Daignault, K. Wojno, and D. M. Robins Glutamine tract length of human androgen receptors affects hormone-dependent and -independent prostate cancer in mice Hum. Mol. Genet., January 1, 2008; 17(1): 98 - 110. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Yin, W.-W. Huang, C. Lin, H. Chen, A. MacKenzie, and L. Ma Estrogen Suppresses Uterine Epithelial Apoptosis by Inducing Birc1 Expression Mol. Endocrinol., January 1, 2008; 22(1): 113 - 125. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. P Risbridger, S. J Ellem, and S. J McPherson Estrogen action on the prostate gland: a critical mix of endocrine and paracrine signaling J. Mol. Endocrinol., September 1, 2007; 39(3): 183 - 188. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. T. Akingbemi, T. D. Braden, B. W. Kemppainen, K. D. Hancock, J. D. Sherrill, S. J. Cook, X. He, and J. G. Supko Exposure to Phytoestrogens in the Perinatal Period Affects Androgen Secretion by Testicular Leydig Cells in the Adult Rat Endocrinology, September 1, 2007; 148(9): 4475 - 4488. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Savolainen, T. Pakarainen, I. Huhtaniemi, M. Poutanen, and S. Makela Delay of Postnatal Maturation Sensitizes the Mouse Prostate to Testosterone-Induced Pronounced Hyperplasia: Protective Role of Estrogen Receptor-{beta} Am. J. Pathol., September 1, 2007; 171(3): 1013 - 1022. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H O Goyal, T D Braden, C S Williams, and J W Williams Role of estrogen in induction of penile dysmorphogenesis: a review Reproduction, August 1, 2007; 134(2): 199 - 208. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Heldring, A. Pike, S. Andersson, J. Matthews, G. Cheng, J. Hartman, M. Tujague, A. Strom, E. Treuter, M. Warner, et al. Estrogen Receptors: How Do They Signal and What Are Their Targets Physiol Rev, July 1, 2007; 87(3): 905 - 931. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Tokumoto, M. Tokumoto, and P. Thomas Interactions of Diethylstilbestrol (DES) and DES Analogs with Membrane Progestin Receptor-{alpha} and the Correlation with Their Nongenomic Progestin Activities Endocrinology, July 1, 2007; 148(7): 3459 - 3467. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Yu, X. Wang, C.-F. Ng, S. Chen, and F. L. Chan ERR{gamma} Suppresses Cell Proliferation and Tumor Growth of Androgen-Sensitive and Androgen-Insensitive Prostate Cancer Cells and Its Implication as a Therapeutic Target for Prostate Cancer Cancer Res., May 15, 2007; 67(10): 4904 - 4914. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H O Goyal, T D Braden, P S Cooke, M A Szewczykowski, C S Williams, P Dalvi, and J W Williams Estrogen receptor-{alpha} mediates estrogen-inducible abnormalities in the developing penis Reproduction, May 1, 2007; 133(5): 1057 - 1067. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Pu, L. Huang, L. Birch, and G. S. Prins Androgen Regulation of Prostate Morphoregulatory Gene Expression: Fgf10-Dependent and -Independent Pathways Endocrinology, April 1, 2007; 148(4): 1697 - 1706. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. J. McPherson, S. J. Ellem, E. R. Simpson, V. Patchev, K.-H. Fritzemeier, and G. P. Risbridger Essential Role for Estrogen Receptor {beta} in Stromal-Epithelial Regulation of Prostatic Hyperplasia Endocrinology, February 1, 2007; 148(2): 566 - 574. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. A. Harris Estrogen Receptor-{beta}: Recent Lessons from in Vivo Studies Mol. Endocrinol., January 1, 2007; 21(1): 1 - 13. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. A. Albertelli, A. Scheller, M. Brogley, and D. M. Robins Replacing the Mouse Androgen Receptor with Human Alleles Demonstrates Glutamine Tract Length-Dependent Effects on Physiology and Tumorigenesis in Mice Mol. Endocrinol., June 1, 2006; 20(6): 1248 - 1260. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. V. Henley and K. S. Korach Endocrine-Disrupting Chemicals Use Distinct Mechanisms of Action to Modulate Endocrine System Function Endocrinology, June 1, 2006; 147(6): s25 - s32. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. J. Bianco, S. J. McPherson, H. Wang, G. S. Prins, and G. P. Risbridger Transient Neonatal Estrogen Exposure to Estrogen-Deficient Mice (Aromatase Knockout) Reduces Prostate Weight and Induces Inflammation in Late Life Am. J. Pathol., June 1, 2006; 168(6): 1869 - 1878. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Kirschenbaum, X.-H. Liu, S. Yao, G. Narla, S. L. Friedman, J. A. Martignetti, and A. C. Levine Sex steroids have differential effects on growth and gene expression in primary human prostatic epithelial cell cultures derived from the peripheral versus transition zones Carcinogenesis, February 1, 2006; 27(2): 216 - 224. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. A Taylor, P. Cowin, J. F. Couse, K. S. Korach, and G. P. Risbridger 17{beta}-Estradiol Induces Apoptosis in the Developing Rodent Prostate Independently of ER{alpha} or ER{beta} Endocrinology, January 1, 2006; 147(1): 191 - 200. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. Imamov, G.-J. Shim, M. Warner, and J.-A. Gustafsson Estrogen Receptor beta in Health and Disease Biol Reprod, November 1, 2005; 73(5): 866 - 871. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. O. Goyal, T. D. Braden, C. S. Williams, P. Dalvi, M. Mansour, and J. W. Williams Estrogen-Induced Abnormal Accumulation of Fat Cells in the Rat Penis and Associated Loss of Fertility Depends upon Estrogen Exposure during Critical Period of Penile Development Toxicol. Sci., September 1, 2005; 87(1): 242 - 254. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. A. Fritz, T.-M. Lin, R. W. Moore, P. S. Cooke, and R. E. Peterson In Utero and Lactational 2,3,7,8-Tetrachlorodibenzo-p-dioxin Exposure: Effects on the Prostate and Its Response to Castration in Senescent C57BL/6J Mice Toxicol. Sci., August 1, 2005; 86(2): 387 - 395. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. D. Cook, B. J. Davis, S.-L. Cai, J. C. Barrett, C. J. Conti, and C. L. Walker Interaction between genetic susceptibility and early-life environmental exposure determines tumor-suppressor-gene penetrance PNAS, June 14, 2005; 102(24): 8644 - 8649. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Atanassova, C. McKinnell, J. Fisher, and R. M Sharpe Neonatal treatment of rats with diethylstilboestrol (DES) induces stromal-epithelial abnormalities of the vas deferens and cauda epididymis in adulthood following delayed basal cell development Reproduction, May 1, 2005; 129(5): 589 - 601. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. Soder Perinatal imprinting by estrogen and adult prostate disease PNAS, February 1, 2005; 102(5): 1269 - 1270. [Full Text] [PDF]
|
|
|
|
|
|
Y. Omoto, O. Imamov, M. Warner, and J.-A. Gustafsson Estrogen receptor {alpha} and imprinting of the neonatal mouse ventral prostate by estrogen PNAS, February 1, 2005; 102(5): 1484 - 1489. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. O. Goyal, T. D. Braden, C. S. Williams, P. Dalvi, M. M. Mansour, and J. W. Williams Permanent Induction of Morphological Abnormalities in the Penis and Penile Skeletal Muscles in Adult Rats Treated Neonatally With Diethylstilbestrol or Estradiol Valerate: A Dose-Response Study J Androl, January 1, 2005; 26(1): 32 - 43. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A Oliveira, G. A B Mahecha, K. Carnes, G. S Prins, P. T K Saunders, L. R Franca, and R. A Hess Differential hormonal regulation of estrogen receptors ER{alpha} and ER{beta} and androgen receptor expression in rat efferent ductules Reproduction, July 1, 2004; 128(1): 73 - 86. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Huang, Y. Pu, S. Alam, L. Birch, and G. S. Prins Estrogenic Regulation of Signaling Pathways and Homeobox Genes During Rat Prostate Development J Androl, May 1, 2004; 25(3): 330 - 337. [Full Text] [PDF]
|
|
|
|
|
|
H.O. Goyal, T.D. Braden, C.S. Williams, P. Dalvi, M.M. Mansour, M. Mansour, J.W. Williams, F.F. Bartol, A.A. Wiley, L. Birch, et al. Abnormal Morphology of the Penis in Male Rats Exposed Neonatally to Diethylstilbestrol Is Associated with Altered Profile of Estrogen Receptor-{alpha} Protein, but Not of Androgen Receptor Protein: A Developmental and Immunocytochemical Study Biol Reprod, May 1, 2004; 70(5): 1504 - 1517. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Tokumoto, M. Tokumoto, R. Horiguchi, K. Ishikawa, and Y. Nagahama Diethylstilbestrol induces fish oocyte maturation PNAS, March 9, 2004; 101(10): 3686 - 3690. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Woodham, L. Birch, and G. S. Prins Neonatal Estrogen Down-Regulates Prostatic Androgen Receptor through a Proteosome-Mediated Protein Degradation Pathway Endocrinology, November 1, 2003; 144(11): 4841 - 4850. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Rivas, C. Mckinnell, J. S. Fisher, N. Atanassova, K. Williams, and R. M. Sharpe Neonatal Coadministration of Testosterone With Diethylstilbestrol Prevents Diethylstilbestrol Induction of Most Reproductive Tract Abnormalities in Male Rats J Androl, July 1, 2003; 24(4): 557 - 567. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Y. Liu, A. K. Death, and D. J. Handelsman Androgens and Cardiovascular Disease Endocr. Rev., June 1, 2003; 24(3): 313 - 340. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Kindblom, K. Dillner, L. Sahlin, F. Robertson, C. Ormandy, J. Tornell, and H. Wennbo Prostate Hyperplasia in a Transgenic Mouse with Prostate-Specific Expression of Prolactin Endocrinology, June 1, 2003; 144(6): 2269 - 2278. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. H. Thin, L. Wang, E. Kim, L. L. Collins, R. Basavappa, and C. Chang Isolation and Characterization of Androgen Receptor Mutant, AR(M749L), with Hypersensitivity to 17-beta Estradiol Treatment J. Biol. Chem., February 21, 2003; 278(9): 7699 - 7708. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. T. Akingbemi, R. Ge, C. S. Rosenfeld, L. G. Newton, D. O. Hardy, J. F. Catterall, D. B. Lubahn, K. S. Korach, and M. P. Hardy Estrogen Receptor-{alpha} Gene Deficiency Enhances Androgen Biosynthesis in the Mouse Leydig Cell Endocrinology, January 1, 2003; 144(1): 84 - 93. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Rivas, J. S. Fisher, C. McKinnell, N. Atanassova, and R. M. Sharpe Induction of Reproductive Tract Developmental Abnormalities in the Male Rat by Lowering Androgen Production or Action in Combination with a Low Dose of Diethylstilbestrol: Evidence for Importance of the Androgen-Estrogen Balance Endocrinology, December 1, 2002; 143(12): 4797 - 4808. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. J. Bianco, D. J. Handelsman, J. S. Pedersen, and G. P. Risbridger Direct Response of the Murine Prostate Gland and Seminal Vesicles to Estradiol Endocrinology, December 1, 2002; 143(12): 4922 - 4933. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Q. Zhou, R. Nie, G. S. Prins, P. T. K. Saunders, B. S. Katzenellenbogen, and R. A. Hess Localization of Androgen and Estrogen Receptors in Adult Male Mouse Reproductive Tract J Androl, November 1, 2002; 23(6): 870 - 881. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z. Weihua, R. Lathe, M. Warner, and J.-A. Gustafsson An endocrine pathway in the prostate, ERbeta , AR, 5alpha -androstane-3beta ,17beta -diol, and CYP7B1, regulates prostate growth PNAS, October 15, 2002; 99(21): 13589 - 13594. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. A. Fritz, I.-E. Eltoum, M. S. Cotroneo, and C. A. Lamartiniere Genistein Alters Growth but Is Not Toxic to the Rat Prostate J. Nutr., October 1, 2002; 132(10): 3007 - 3011. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. H. Thin, E. Kim, S. Yeh, E. R. Sampson, Y.-T. Chen, L. L. Collins, R. Basavappa, and C. Chang Mutations in the Helix 3 Region of the Androgen Receptor Abrogate ARA70 Promotion of 17beta -Estradiol-induced Androgen Receptor Transactivation J. Biol. Chem., September 20, 2002; 277(39): 36499 - 36508. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. S. Prins, W. Y. Chang, Y. Wang, and R. B. van Breemen Retinoic Acid Receptors and Retinoids Are Up-Regulated in the Developing and Adult Rat Prostate by Neonatal Estrogen Exposure Endocrinology, September 1, 2002; 143(9): 3628 - 3640. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M.-M. Liu, C. Albanese, C. M. Anderson, K. Hilty, P. Webb, R. M. Uht, R. H. Price Jr., R. G. Pestell, and P. J. Kushner Opposing Action of Estrogen Receptors alpha and beta on Cyclin D1 Gene Expression J. Biol. Chem., June 28, 2002; 277(27): 24353 - 24360. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |
P < 0.05 when comparing treatments within the same genotype; n = 9–17 for all of the groups.
