Transdifferentiation of adult rat stem Leydig cells into prostatic and uterine epithelium, but not epidermis

Stem Leydig cells (SLCs), precursors of testicular Leydig cells that secrete testosterone required for male sexual differentiation, spermatogenesis, and fertility, were recently identified in rat testes. Various types of stem cells have shown the ability to differentiate into other tissues, but there is no information on the plasticity of adult rat SLCs (rSLCs). This study investigated the ability of rSLCs to transdifferentiate into cell types from all three germ layers-prostatic epithelium (endoderm), uterine epithelium (mesoderm), and epidermis (ectoderm)-under the influence of inductive mesenchyme from fetal and neonatal tissues. To differentiate rSLCs into cells of other lineages, mesenchyme from green fluorescent protein (GFP)-expressing mice was used. Tissue recombinants of urogenital sinus mesenchyme (a potent prostate inducer) and rSLCs grafted into adult male hosts formed ductal structures resembling prostate after 5 weeks. Prostate epithelium was of rSLC origin as determined by absence of GFP expression, and expressed characteristic markers of prostatic epithelium. Similarly, uterine mesenchyme + rSLCs tissue recombinants contained a simple columnar epithelium that was histologically similar to normal uterine epithelium and expressed typical uterine epithelial markers, but was of rSLC origin. In contrast, epidermal tissue was absent in fetal dermis + rSLCs recombinants, suggesting rSLCs did not form skin epithelium. Thus, rSLCs can transdifferentiate into uterine and prostatic epithelium, mesodermal, and endodermal derivatives, respectively, but they may have a limited transdifferentiation potential, as shown by their inability to form epidermis, an ectodermal derivative.

ID: 85: CROSS-TALK BETWEEN ESTROGEN RECEPTORS AND INSULIN-LIKE GROWTH FACTOR TYPE-1 RECEPTOR MODULATES HUMAN PROSTATE STEM/PROGENITOR CELL AMPLIFICATION

We previously demonstrated that estrogen regulates human prostate stem/progenitor cell amplification by directly targeting estrogen receptors (ERs); ERα stimulates whereas ERβ suppresses stem cell self-renewal. In addition to ERα and ERβ, we find that human prostate stem/progenitor cells express robust level of IGF-1R. Since ER actions can be modified by IGF-1R through ligand-independent ER phosphorylation, we herein sought to characterize potential cross-talk between estrogen and IGF-1 signaling pathways in regulating human prostate stem/progenitor cell amplification. Human prostate stem/progenitor cells were isolated from normal primary prostate epithelial cells (PrEC) using 3-D prostasphere (PS) culture. Similar to estradiol-17β (E2), 5 nM IGF-1 treatment increased the number of PS as well as long-term BrdU-retaining prostate stem cells. Conversely, knockdown of IGF-1R by siRNA decreased both parameters and consistently increased PS ERβ expression. Together these findings suggest that IGF-1R activation may drive prostate stem cell amplification through suppression of ERβ. Further studies revealed that E2 (10 nM) exposure induced IGF-1R phosphorylation while IGF-1R knockdown inhibited the non-genomic E2-induced pAkt and pERK confirming the cross-talk between these two signaling pathways. IGF-1R knockdown decreased PHLDA1, a known IGF-1 target gene, inhibited E2-induced ERα phosphorylation, suggesting a positive interaction between IGF-1R and ERα. In summary, the present results document robust crosstalk between estrogen and IGF-1 signaling which together regulate their downstream signal molecules including pAKT/pERK and PHLDA1. We propose that these pathways coordinately modulate prostate stem and progenitor cell numbers to effectively maintain glandular homeostasis. Supported by NIH/NCI award R01 CA172220; scholarship by FAPESP grant#2014/10965-6.

ID: 22: DIFFERENTIAL ACTIONS OF ESTROGEN RECEPTOR α AND β VIA NON-GENOMIC SIGNALING IN HUMAN PROSTATE STEM-PROGENITOR CELLS

Genomic signaling via estrogen receptors (ER) has been widely studied and implicated as the main ER signaling pathway in prostate development and carcinogenesis. Non-genomic ER signaling has also been reported in prostate epithelium although down-stream cascades have not been clarified. Our lab has recently identified ERs in human prostate epithelial stem/progenitor cells and shown that that 17β-estradiol (E2) can stimulate stem cell symmetric self-renewal and progenitor cell proliferation. In this study we interrogate non-genomic membrane initiated ER signaling in this prostate stem/progenitor cell population. Human prostate stem-progenitor cells were enriched from primary prostate epithelial cell cultures (PrEC) of young, disease-free donors using a 3D prostasphere (PS) model as previously described. Cells were labeled using ERα or ERβ antibodies along with prostate stem cell markers CD49f and TROP2 followed by triple channel FACS to quantify ERα+/ERβ+ cell numbers. To explore ERα, the benign human prostate stem cell line WPE with extremely low levels of ERα and ERβ, was stably transfected with a lentiviral-ERα expression vector. The human prostate cancer stem-like cell line HuSLC (ERβ++, ERα−) was utilized to interrogate ERb actions. Cells were exposed to 10 nM estradiol (E2) over a 15 to 60 minute time course +/− ICI 182,870 (ICI), an ERα/β antagonist. FACS analysis of day 7 PS cells labeled for ERα or ERβ revealed 66% of day 7 PS cells as ERα+ and 40% as ERβ+. Among ERα or ERβ positive PS cells, 4% were Trop2+/CD49fhigh (stem-like cells) and 10–12% were Trop2+/CD49fmedium (early stage progenitor cells). PS exposed to 10 nM E2 showed sequential phosphorylation of Src, Erk1/2, p38, Akt and NFκB (p65) over 60 minutes. Phosphorylation of up-and downstream targets (EGFR, Jnk, GSK 3α/β, p70 S6 kinase, PRAS40, MSK1/2) was also seen using a phospho-kinase array. Furthermore, phosphorylation of ERα at S167 was noted over 60 min of E2 exposure enabling enhancement of genomic ERα transactivational activity in a feed-forward manner. ICI attenuated Akt and Erk1/2 phosphorylation, confirming membrane bound ERs are involved in downstream signaling. E2 treatment of HuSLCs showed phosphorylation of Erk1/2 but not Akt, indicating that ERβ signals exclusively through the MAPK pathway in these cells. Conversely, E2 treatment of WPE-stem cells overexpressing ERα resulted in robust phosphorylation of Akt but lower levels of Erk1/2 phosphorylation suggesting that Akt activation may be more reliant on ERα signaling. To identify pathway specific roles, specific inhibitors were added to PS cultures. PS treated with LY294002 (Akt inhibitor) for 7 days attenuated the E2-mediated increase in PS number and size. Inhibition of the NFκB downstream of the Akt pathway by IKK VII (IKK inhibitor) blocked p65 phosphorylation, abrogated the E2-induced increase in stem cell symmetric self-renewal and blunted E2 stimulation of progenitor cell proliferation. Analysis of PS cyclin mRNA levels revealed a G1 arrest of progenitor cells upon IKK inhibition suggesting an essential role of NFκB in progenitor cell amplification. MAPK pathway inhibition with U0126(Erk1/2 inhibitor) resulted in an attenuation of the E2-mediated increase in PS number and size and an increase stem cell symmetric self-renewal suggesting that MAPK pathway activation promotes commitment to stem and progenitor cell expansion. Taken together, the present findings reveal that human prostate stem-progenitor cells express both ERα and ERβ which differentially activate different signaling cascades originating at the membrane. These signaling events may lead to unique downstream actions that influence prostate stem-progenitor cell proliferation as well as lineage commitment decisions.

Executive Summary to EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals

This Executive Summary to the Endocrine Society's second Scientific Statement on environmental endocrine-disrupting chemicals (EDCs) provides a synthesis of the key points of the complete statement. The full Scientific Statement represents a comprehensive review of the literature on seven topics for which there is strong mechanistic, experimental, animal, and epidemiological evidence for endocrine disruption, namely: obesity and diabetes, female reproduction, male reproduction, hormone-sensitive cancers in females, prostate cancer, thyroid, and neurodevelopment and neuroendocrine systems. EDCs such as bisphenol A, phthalates, pesticides, persistent organic pollutants such as polychlorinated biphenyls, polybrominated diethyl ethers, and dioxins were emphasized because these chemicals had the greatest depth and breadth of available information. The Statement also included thorough coverage of studies of developmental exposures to EDCs, especially in the fetus and infant, because these are critical life stages during which perturbations of hormones can increase the probability of a disease or dysfunction later in life. A conclusion of the Statement is that publications over the past 5 years have led to a much fuller understanding of the endocrine principles by which EDCs act, including nonmonotonic dose-responses, low-dose effects, and developmental vulnerability. These findings will prove useful to researchers, physicians, and other healthcare providers in translating the science of endocrine disruption to improved public health.

EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals

The Endocrine Society's first Scientific Statement in 2009 provided a wake-up call to the scientific community about how environmental endocrine-disrupting chemicals (EDCs) affect health and disease. Five years later, a substantially larger body of literature has solidified our understanding of plausible mechanisms underlying EDC actions and how exposures in animals and humans-especially during development-may lay the foundations for disease later in life. At this point in history, we have much stronger knowledge about how EDCs alter gene-environment interactions via physiological, cellular, molecular, and epigenetic changes, thereby producing effects in exposed individuals as well as their descendants. Causal links between exposure and manifestation of disease are substantiated by experimental animal models and are consistent with correlative epidemiological data in humans. There are several caveats because differences in how experimental animal work is conducted can lead to difficulties in drawing broad conclusions, and we must continue to be cautious about inferring causality in humans. In this second Scientific Statement, we reviewed the literature on a subset of topics for which the translational evidence is strongest: 1) obesity and diabetes; 2) female reproduction; 3) male reproduction; 4) hormone-sensitive cancers in females; 5) prostate; 6) thyroid; and 7) neurodevelopment and neuroendocrine systems. Our inclusion criteria for studies were those conducted predominantly in the past 5 years deemed to be of high quality based on appropriate negative and positive control groups or populations, adequate sample size and experimental design, and mammalian animal studies with exposure levels in a range that was relevant to humans. We also focused on studies using the developmental origins of health and disease model. No report was excluded based on a positive or negative effect of the EDC exposure. The bulk of the results across the board strengthen the evidence for endocrine health-related actions of EDCs. Based on this much more complete understanding of the endocrine principles by which EDCs act, including nonmonotonic dose-responses, low-dose effects, and developmental vulnerability, these findings can be much better translated to human health. Armed with this information, researchers, physicians, and other healthcare providers can guide regulators and policymakers as they make responsible decisions.

Neurodistribution of androgen receptor immunoreactivity in the male frog, Rana esculenta

Sexual behavior in vertebrates depends on the cyclic release of steroids and their binding to the brain receptors. Previously, we demonstrated the presence of specific binding of (3)H-testosterone and staining with PG-21 in the brain of the adult male frog, Rana esculenta. Here, we report our further receptor characterization using an anti-androgen receptor antiserum, PG-21, and the androgen site of action in frog brain. Nuclei, which contained cells labeled for the androgen receptor (AR), were mainly identified in the olfactory bulbs, preoptic-septal region, infundibulum, amygdala, thalamus, tectum, torus semicircularis, and medulla. The neuroanatomical AR staining appears similar to that in other lower vertebrates.

Abnormal Morphology of the Penis in Male Rats Exposed Neonatally to Diethylstilbestrol Is Associated with Altered Profile of Estrogen Receptor-α Protein, but Not of Androgen Receptor Protein: A Developmental and Immunocytochemical Study1

Objectives of the study were to determine developmental changes in morphology and expression of androgen receptor (AR) and estrogen receptor (ER)alpha in the body of the rat penis exposed neonatally to diethylstilbestrol (DES). Male pups received DES at a dose of 10 microg per rat on alternate days from Postnatal Day 2 to Postnatal Day 12. Controls received olive oil vehicle only. Tissue samples were collected on Days 18 (prepuberty), 41 (puberty), and 120 (adult) of age. DES-induced abnormalities were evident at 18 days of age and included smaller, lighter, and thinner penis, loss of cavernous spaces and associated smooth muscle cells, and increased deposition of fat cells in the corpora cavernosa penis. Fat cells virtually filled the entire area of the corpora cavernosa at puberty and adulthood. Plasma testosterone (T) was reduced to an undetectable level, while LH was unaltered in all treated groups. AR-positive cells were ubiquitous and their profile (incidence and staining intensity) did not differ between control and treated rats of the respective age groups. Conversely, ERalpha-positive cells were limited to the stroma of corpus spongiosus in all age groups of both control and treated rats, but the expression in treated rats at 18 days was up-regulated in stromal cells of corpora cavernosa, coincident with the presence of morphological abnormalities. Hence, this study reports for the first time DES-induced developmental, morphological abnormalities in the body of the penis and suggests that these abnormalities may have resulted from decreased T and/or overexpression of ERalpha.

Influence of neonatal estrogens on rat prostate development

Brief exposure of rodents to estrogens during early development alters prostate branching morphogenesis and cellular differentiation in a dose-dependant manner. If estrogenic exposures are high, these disturbances lead to permanent imprints of the prostate, which include reduced growth, differentiation defects of the epithelial cells, altered secretory function and reduced responsiveness to androgens in adulthood. This process, referred to as neonatal imprinting or developmental estrogenization, is associated with an increased incidence of prostatic lesions with aging, which include hyperplasia, inflammation and dysplasia. To better understand how early estrogenic exposures can permanently alter prostate growth and function and predispose the gland to neoplasia, the effects of estrogens on prostatic steroid receptors, cell-cell communication molecules and key developmental genes were examined. Transient and permanent alterations in the expression of prostatic androgen receptors, estrogen receptors alpha (ERalpha) and beta, and retinoic acid receptors are observed. It is proposed that the estrogen-induced alterations in these critical transcription factors play a fundamental role in initiating prostatic growth and differentiation defects. Down-stream effects of the altered steroid receptor expression include disruption of TGFbeta paracrine communication, altered expression of gap junction connexin molecules and loss of epithelial cadherin on epithelial cells. Additionally, specific disruptions in the expression of prostatic developmental genes are observed in response to neonatal estrogen. An extended developmental period of hoxa-13 expression, a lack of hoxd-13 increase with maturation, and an immediate and sustained suppression of hoxb-13 was noted within prostatic tissue. A transient decrease in Nkx3.1 expression in the developing prostate was also observed. Thus subtle and overt alterations in Hox-13 and Nkx3.1 genes may be involved in the altered prostate phenotype in response to neonatal estrogen exposure. In summary, estrogen imprinting of the prostate gland is mediated through up-regulated levels of stromal ERalpha, which initiates alterations in steroid receptor expression within the developing gland. Rather than being an androgen-dominated process, as occurs normally, prostatic development is regulated by alternate steroids, including estrogens and retinoids, in the estrogenized animal. This, in turn, leads to disruptions in the coordinated expression of critical developmental genes including TGFbeta, Hox-13 genes and Nkx3.1. Since a precise temporal expression pattern of these and other molecules is normally required for appropriate differentiation of the prostatic epithelium and stroma, the estrogen-initiated disruption in this pattern would lead to permanent differentiation defects of the prostate gland. It is hypothesized that these molecular and cellular changes initiated early in life predispose the prostate to the neoplastic state upon aging.

Alterations in gap junction protein expression in human benign prostatic hyperplasia and prostate cancer

PURPOSE

Gap junctions composed of connexin proteins have an essential role in intercellular communication and differentiation. Dysregulation of connexin expression is believed to have a role in carcinogenesis. The human prostate has been reported to express connexin 32 and 43. However, the expression pattern in prostate cancer is controversial, while to our knowledge connexin expression has not been reported in benign prostatic hyperplasia (BPH). To understand the potential involvement in prostate disease connexin 32 and 43 expression was evaluated in a series of normal prostate, BPH and prostate cancer specimens that were surgically removed due to bladder outlet obstruction.

MATERIALS AND METHODS

Frozen sections of 23 normal, 43 BPH and 40 cancer involved prostates were evaluated for the presence, staining intensity and pattern of connexin 32 and 43 by immunocytochemical testing.

RESULTS

In all specimens examined connexin 43 stain was punctate along the borders of the basal epithelial cells, whereas connexin 32 immunolocalized to luminal epithelial cells. In normal prostate connexin 43 and 32 were present in 87% and 65% of specimens, respectively, at low to moderate stain intensity. Importantly none of the normal samples were negative foreach connexin. In BPH specimens there was a marked increase in the incidence and intensity of connexin 43 and 32 immunostaining within epithelial cells. In addition, 23% of BPH samples showed strong connexin 43 expression in stromal cells. In contrast, connexin was decreased in prostate cancer specimens, of which 65% and 38% were negative for connexin 43 and 32, respectively, and 28% were negative for each type. In poorly differentiated tumors connexin 43 and 32 were present in only 10% and 40% of tumors, respectively, at low immunostaining intensity.

CONCLUSIONS

In normal human prostate basal cells communicate via connexin 43 gap junctions, whereas luminal cells communicate via connexin 32 gap junctions. In BPH gap junctional intercellular communication is increased in epithelial and stromal cells, which may have a role in BPH pathogenesis. In prostate cancer gap junctional intercellular communication is decreased, is as indicated by decreased expression of connexin 43 and 32 with severe loss in poorly differentiated prostate cancer. These alterations in connexin expression may have a role in dedifferentiation and tumor progression.

Neonatal low- and high-dose exposure to estradiol benzoate in the male rat: II. Effects on male puberty and the reproductive tract

Environmental contaminants with estrogenic properties have been cause for heightened concern about their possible role in inducing adverse health effects. Brief exposure of rodents to high doses of natural estrogens early in life results in permanent alterations of the male reproductive tissues, but the question of whether environmentally relevant doses can cause the same effects remains controversial. The current project was designed to determine the dose-response relationship between neonatal estradiol exposure and the development of the male reproductive tract in the rat. Neonatal male Sprague-Dawley (SD) and Fisher 344 (F344) rats were exposed to beta-estradiol-3-benzoate (EB) at concentrations ranging from 0.015 microg/kg body weight (BW) to 15.0 mg/kg BW and 0.15 microg/kg BW to 1.5 mg/kg BW, respectively. Results showed an inverted U-shaped dose-response profile for testis and epididymis weights in 35-day-old SD rats, with increased organ sizes at the low-dose end of the treatment. This effect was transient and was not sustained into adulthood. Increased hepatic testosterone hydroxylase activities in low-dose animals suggest an advancement of puberty as the cause for increased reproductive organ weights. On postnatal day (PND) 90, a stimulatory low-dose response to EB was present in SD rat testicular and epididymal weights, however at one order of magnitude lower dose than that seen on PND 35, suggesting a separate effect. All SD male reproductive tract organs and serum hormones showed a permanent inhibitory response to high doses of neonatal EB. F344 rats exhibited greater estrogen sensitivity on PND 90. Despite this heightened responsiveness, F344 rats did not exhibit a low-dose effect for any endpoint. These low-dose responses to estradiol are organ and strain specific.

Neonatal low- and high-dose exposure to estradiol benzoate in the male rat: I. Effects on the prostate gland

Brief exposure of rats to high doses of natural estrogens early in life results in permanent alterations of the prostate gland, which include differentiation defects, altered gene expression, and dysplasia with aging. Whether low-dose treatments can cause similar effects in the developing prostate remains controversial. The current project was designed to determine the dose-response relationship of the prostate gland to estradiol exposure during the developmentally critical neonatal period in the rat. Male Sprague-Dawley (SD) rats were treated on Days 1, 3, and 5 of life by s.c. injections of a 7-log range of doses (0.015 microg/kg to 15.0 mg/kg) of beta-estradiol-3-benzoate (EB) in 25 microl of peanut oil (Arachis) as vehicle. In a separate block, neonatal Fisher 344 (F344) rats received 0.15, 15.0, or 1500.0 microg EB/kg. Rats were killed on Postnatal Day (PND) 35 or 90, and the prostates were microdissected, weighed, and frozen for immunohistochemistry. Preputial separation and hepatic testosterone hydroxlase activities were monitored and measured to determine the onset of puberty. On PND 35, there was an increase in prostate weights of SD rats treated with low doses of EB and a decrease in prostate weights of SD rats treated with high doses. The low-dose effect was entirely abolished by PND 90, and only high-dose suppression of organ sizes was found. The transient nature of the effect in low-dose animals suggests an advancement of puberty as the cause for increased reproductive organ weights on PND 35. F344 rats were more sensitive than SD rats to the suppressive effects of high doses of neonatal EB on PND 90. Despite this heightened responsiveness in the F344 rats, a low-dose estrogenic effect on adult prostate weights was not observed. Thus, in the rat model a sustained effect at low doses of natural estrogens is not present in the prostate glands.

Androgen receptor mediates the reduced tumor growth, enhanced androgen responsiveness, and selected target gene transactivation in a human prostate cancer cell line

The growth and development of the prostate gland are regulated by the androgen and the androgen receptor (AR). Despite our molecular understanding of the roles of the AR regulating; a downstream target gene transcription, the direct or indirect (stromally mediated) actions of the androgen in controlling prostate cell growth and differentiation are still unclear. In this report, an invasive; and metastatic human prostate tumor cell line, androgen-repressed human prostate cancer cell line (ARCaP), either transduced with wild-type human AR (hAR) or a control neomycin-resistant plasmid DNA, was used to evaluate the direct role of AR in regulating prostate tumor cell growth and gene transcription. Results showed that: (a) introduction of wild-type hAR to ARCaP cells restored positive androgen regulation of prostate tumor cell growth in vitro through an enhanced cell-cycle progression from G(0)/G(1) to S and G(2)-M phases; (b) hAR was shown to transactivate glucocorticoid-responsive element but not prostate-specific antigen promoter-directed reporter gene expression; and (c) hAR-transduced ARCaP cells exhibited reduced growth, invasion, and migratory behavior in vitro and tumor growth in vivo. These results suggest that the introduction of hAR into the invasive human prostate cancer ARCaP cell line restored its androgen-regulated cell growth, decreased the rate of tumor growth, and selectively activated AR target gene expression. These cellular functions in response to androgen are commonly associated with increased differentiation of prostate epithelial cells.

Estrogen imprinting of the developing prostate gland is mediated through stromal estrogen receptor alpha: studies with alphaERKO and betaERKO mice

Neonatal exposure of rodents to high doses of estrogen permanently imprints the growth and function of the prostate and predisposes this gland to hyperplasia and severe dysplasia analogous to prostatic intraepithelial neoplasia with aging. Because the rodent prostate gland expresses estrogen receptor (ER)-alpha within a subpopulation of stromal cells and ERbeta 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) alpha -/- mice, and betaERKO -/- mice were injected with 2 microg 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, ERalpha, ERbeta, 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 ERalpha, down-regulation of androgen receptor, decreased ERbeta 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 alphaERKO 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 betaERKO mice resulted in a prostatic response similar to that observed in WT animals. The present findings indicate that ERalpha is the dominant ER form mediating the developmental estrogenization of the prostate gland. If epithelial ERbeta is involved in some component of estrogen imprinting, its role would be considered minor and would require the presence of ERalpha expression in the prostatic stromal cells.

Simultaneous determination of all-trans, 9-cis, 13-cis retinoic acid and retinol in rat prostate using liquid chromatography-mass spectrometry

Since retinoic acid (RA) and RA receptors are key developmental regulators during organogenesis, they might participate in the abnormal development of the prostate caused by early estrogen exposure. In order to test this assumption, a sensitive analytical method that can differentiate 9-cis, 13-cis, and all-trans RA in small tissue samples ( approximately 8 mg) is required. Since retinol is the metabolic precursor to RA, simultaneous quantification of retinol would also provide valuable information. Here, we report a liquid chromatography-mass spectrometry method for simultaneous determination of retinol and 9-cis, 13-cis, and all-trans RA in rat prostate. Mass spectrometric signal responses for RA were compared using positive ion atmospheric-pressure chemical ionization (APCI) and electrospray, as well as positive ion and negative ion APCI. Positive ion APCI was selected for all subsequent analysis for its better sensitivity, and to provide simultaneous determination of retinol and RA. Ventral prostate tissue samples were homogenized and extracted following simple protein precipitation without derivatization. Baseline separation of 9-cis, 13-cis, and all-trans RA standards was obtained by using a non-porous silica C18 column. Selected ion monitoring of the ions m/z 301 and m/z 269 was carried out for mass spectrometric quantitative analysis. The ion of m/z 301 corresponded to the protonated molecule of RA, whereas the ion of m/z 269 corresponded to loss of water or acetic acid from the protonated molecule of retinol or the internal standard retinyl acetate respectively. The method has a linear response over a concentration range of at least three orders of magnitude. The limit of quantitation was determined to be 702 fmol all-trans RA injected on-column. The method showed excellent intra- and inter-assay reproducibility and good recovery, and is suitable for analyzing RA and retinol in small tissue samples (approximately 8 mg).

Testosterone protects cerebellar granule cells from oxidative stress-induced cell death through a receptor mediated mechanism

It is known that steroid hormones can affect neuronal susceptibility to different types of insults, including oxidative stress. Using an in vitro/ex vivo model, we have previously shown that cerebellar granule cells prepared from neonatal rats treated with a single dose of testosterone are less vulnerable to oxidative stress-induced cell death, via a mechanism involving an upregulation of the cellular antioxidant defenses. Whether the testosterone protective action on cerebellar granule cells was direct or indirect remained to be clarified. Therefore, in this study we have investigated the effects of in vitro testosterone treatment, to see whether it also protects cerebellar granule cells from oxidative stress-induced damage. Cerebellar granule cells treated with 10(-6) M testosterone for 48 h were found less susceptible to damage induced by 50 microM hydrogen peroxide, as shown by a 30% decrease in the number of cells with apoptotic morphology. The addition of the androgen receptor antagonist flutamide abolished the protective effect of testosterone, suggesting an androgen receptor-mediated mechanism. This hypothesis was further supported by the presence of the androgen receptor in cultured cerebellar granule cells. The activity of the antioxidant enzyme catalase was also measured, and a 2-fold increase was detected in the testosterone treated cells, but not in the cells co-treated with flutamide. The present results demonstrate that cerebellar granule cells treated in vitro with testosterone are protected from oxidative stress via a mechanism mediated by the androgen receptor. Similarly to what we observed after in vivo administration of testosterone, the potentiation of the antioxidant defences seems to play a major role in the protection afforded by testosterone.

Developmental exposure to estrogens alters epithelial cell adhesion and gap junction proteins in the adult rat prostate

Brief exposure to estrogens during the neonatal period interrupts rat prostatic development by reducing branching morphogenesis and by blocking epithelial cells from entering a normal differentiation pathway. Upon aging, ventral prostates exhibit extensive hyperplasia and dysplasia suggesting that neonatal estrogens may predispose the prostate gland to preneoplastic lesions. To determine whether these prostatic lesions may be manifested through aberrant cell-to-cell communications, the present study examined specific gap junction proteins, Connexins (Cx) 32, and Cx 43, and the cell adhesion molecule, E-cadherin, in the developing, adult and aged rat prostate gland. Male rat pups were given 25 microgram estradiol benzoate or oil on days 1, 3, and 5 of life. Prostates were removed on days 1, 4, 5, 6, 10, 15, 30, or 90 or at 16 months, and frozen sections were immunostained for E-cadherin, Cx 43, and Cx 32. Colocalization studies were performed with immunofluorescence using specific antibodies for cell markers. Gap junctions in undifferentiated epithelial cells at days 1-10 of life were composed of Cx 43, which always colocalized with basal cell cytokeratins (CK 5/15). Cx 32 expression was first observed between days 10-15 and colocalized to differentiated luminal cells (CK 8/18). Cx 43 and Cx 32 never colocalized to the same cell indicating that gap junction intercellular communication differs between basal and luminal prostatic cells. While epithelial connexin expression was not initially altered in the developing prostates following estrogen exposure, adult prostates of neonatally estrogenized rats exhibited a marked decrease in Cx 32 staining and an increased proportion of Cx 43 expressing cells. In the developing prostate, E-cadherin was localized to lateral surfaces of undifferentiated epithelial cells and staining intensity increased as the cells differentiated into luminal cells. By day 30, estrogenized prostates had small foci of epithelial cells that did not immunostain for E-cadherins. In the adult and aged prostates of estrogenized rats, larger foci with differentiation defects and dysplasia were associated with a decrease or loss in E-cadherin staining. The present findings suggest that estrogen-induced changes in the expression of E-cadherin, Cx32 and Cx43 may result in impaired cell-cell adhesion and defective cell-cell communication and may be one of the key mechanisms through which changes toward a dysplastic state are mediated. These findings are significant in light of the data on human prostate cancers where carcinogenesis and progression are associated with loss of E-cadherin and a switch from Cx32 to Cx43 expression in the epithelium.

Distribution of mRNAs encoding CRF receptors in brain and pituitary of rat and mouse

Two G protein-coupled receptors have been identified that bind corticotropin-releasing factor (CRF) and urocortin (UCN) with high affinity. Hybridization histochemical methods were used to shed light on controversies concerning their localization in rat brain, and to provide normative distributional data in mouse, the standard model for genetic manipulation in mammals. The distribution of CRF-R1 mRNA in mouse was found to be fundamentally similar to that in rat, with expression predominating in the cerebral cortex, sensory relay nuclei, and in the cerebellum and its major afferents. Pronounced species differences in distribution were few, although more subtle variations in the relative strength of R1 expression were seen in several forebrain regions. CRF-R2 mRNA displayed comparable expression in rat and mouse brain, distinct from, and more restricted than that of CRF-R1. Major neuronal sites of CRF-R2 expression included aspects of the olfactory bulb, lateral septal nucleus, bed nucleus of the stria terminalis, ventromedial hypothalamic nucleus, medial and posterior cortical nuclei of the amygdala, ventral hippocampus, mesencephalic raphe nuclei, and novel localizations in the nucleus of the solitary tract and area postrema. Several sites of expression in the limbic forebrain were found to overlap partially with ones of androgen receptor expression. In pituitary, rat and mouse displayed CRF-R1 mRNA signal continuously over the intermediate lobe and over a subset of cells in the anterior lobe, whereas CRF-R2 transcripts were expressed mainly in the posterior lobe. The distinctive expression pattern of CRF-R2 mRNA identifies additional putative central sites of action for CRF and/or UCN. Constitutive expression of CRF-R2 mRNA in the nucleus of the solitary tract, and stress-inducible expression of CRF-R1 transcripts in the paraventricular nucleus may provide a basis for understanding documented effects of CRF-related peptides at a loci shown previously to lack a capacity for CRF-R expression or CRF binding. Other such "mismatches" remain to be reconciled.

Androgen receptor-immunoreactivity in the forebrain of the Eastern Fence lizard (Sceloporus undulatus)

Androgen receptor (AR) distribution in the lizard forebrain and optic tectum was examined using PG21 immunohistochemistry. In the male Eastern Fence lizard, AR-immunoreactive (-ir) nuclei were observed in the medial preoptic area, ventromedial and arcuate hypothalamic nuclei, periventricular hypothalamus, premammillary nucleus, bed nucleus of the stria terminalis, and ventral posterior amygdala. Punctate immunostaining of neuronal processes (axons and/or dendrites) was concentrated in the cortex, hypothalamus, and optic tectum. AR-ir nuclei in the female brain were confined to the ventral posterior amygdala and ventromedial hypothalamic nucleus. The AR distribution in the lizard brain is similar to that reported for other vertebrate classes. Sex differences in AR-immunoreactivity may contribute to sex-specific behaviors in the Eastern Fence lizard.

Evidence that estrogens directly alter androgen-regulated prostate development

Neonatal exposure to high doses of estrogen results in permanent suppression of prostate growth and reduced sensitivity to androgens in adulthood. It is unclear whether alterations in prostate growth are due to a direct effect of estrogens on the gland or are the result of hypothalamic-pituitary-gonadal axis suppression and a subsequent reduction in androgen levels. Therefore, the aim of this study was to determine whether estrogens have a direct effect on the prostate using a defined method of culturing neonatal prostates. Newborn rat ventral prostates were microdissected and cultured in the presence of testosterone, which resulted in branching morphogenesis and ductal canalization. Solid cords of epithelium differentiated into acini lined by tall columnar epithelial cells; these acini were surrounded by stromal cells, expressing smooth muscle alpha-actin. When cultured in the presence of 17beta-estradiol or diethylstilbestrol in addition to testosterone, androgen-induced prostatic growth was reduced, and differentiation was altered. Although estrogen-treated explants were smaller than controls, quantification of epithelial, stromal, and luminal volumes using unbiased stereology revealed significant changes; the proportion of epithelial cells and lumen decreased, and the proportion of stroma increased compared with control values. Concurrent with this reduced growth rate, we observed a disturbance in the branching pattern and a reduction in ductal canalization. Specifically, stromal differentiation and organization were disrupted, so that a discontinuous smooth muscle layer was observed around the epithelial ducts, and epithelial differentiation was altered. The effects of estrogens were not accompanied by a decrease in androgen response via the androgen receptor, because immunolocalization of this receptor remained constant. These data demonstrate that high doses of estrogens are growth inhibitory and have direct effects on prostate development in vitro, which may occur in vivo in addition to indirect effects via suppression of the hypothalamic-pituitary-gonadal axis.

In vitro fertilization outcomes after intracytoplasmic sperm injection with fresh or frozen-thawed testicular spermatozoa

OBJECTIVE

To compare the outcomes of intracytoplasmic sperm injection (ICSI) and in vitro fertilization (IVF) with fresh and cryopreserved testicular spermatozoa in patients with obstructive and nonobstructive azoospermia.

DESIGN

Retrospective analysis of consecutive ICSI cycles.

SETTING

Large urban reproductive medicine program.

PATIENT(S)

Twenty-nine patients with obstructive and nonobstructive azoospermia undergoing testicular sperm extraction for a total of 46 IVF-ICSI cycles (12 fresh, 34 frozen).

INTERVENTION(S)

Testicular sperm extraction, cryopreservation, and IVF-ICSI with fresh or frozen-thawed spermatozoa.

MAIN OUTCOME MEASURE(S)

Fertilization rates, embryo cleavage rates, embryo implantation rates, clinical pregnancy rates per cycle and per embryo transfer, and delivery and spontaneous abortion rates.

RESULT(S)

No statistically significant differences were noted in any of the parameters examined between IVF-ICSI cycles from fresh or frozen-thawed testicular spermatozoa. Fertilization rates were 56% with fresh vs. 61% with frozen-thawed testicular sperm, cleavage rates 92% vs. 95%, implantation rates 26% vs. 17%, clinical pregnancy rates per cycle 33% vs. 41%, and pregnancy rates per embryo transfer 33% vs. 45%, respectively. Delivery rates were 75% with fresh vs. 69.2% with frozen-thawed testicular sperm, and spontaneous abortion rates 25% and 30.8%, respectively.

CONCLUSION(S)

No differences were found in IVF-ICSI outcomes between cryopreserved and fresh testicular sperm. In addition, cryopreservation provides several advantages for the patients and reproductive team.

Molecular biology of the androgen receptor

The androgen receptor is a member of a superfamily of nuclear transcription factors that mediate the action of steroid hormones. When activated by ligand binding, these transcription factors bind to specific DNA sequences on target genes and regulate the transcriptional activity of those genes. Various genes have been identified that are regulated by androgens, including prostate-specific antigen (PSA). PSA contains an upstream glucocorticoid response element/androgen response element, so it is believed that androgens directly regulate its transcription rate. Despite this, posttranscriptional regulation through stability of the messenger RNA product is believed to be a major mechanism of androgens' effects.

Estrogen receptor-beta: implications for the prostate gland

Estrogens can have profound effects on prostate growth and differentiation. These effects were thought to be mediated by the classical estrogen receptor; however, the discovery of a second estrogen receptor has redefined the estrogen signaling pathway and may have broad implications on estrogen-responsive tissues, including the prostate. The new estrogen receptor, named estrogen receptor-beta (ERbeta), is preferentially expressed in the prostate and maintains some characteristics that are different from ERalpha. Establishing the distribution and function of ERbeta in the various estrogen-responsive tissues is critical to defining its pharmacological and physiological impact. Differential expression of ERbeta may facilitate development of tissue-specific estrogen agonists and antagonists, a goal in the treatment of diseases in estrogen-sensitive tissues such as breast cancer. This article reviews the current knowledge on ERbeta and its potential impact on the prostate.

Neonatal estrogen exposure alters the transforming growth factor-beta signaling system in the developing rat prostate and blocks the transient p21(cip1/waf1) expression associated with epithelial differentiation

Exposure of male rats to estrogens during the neonatal period retards prostate branching morphogenesis, blocks epithelial differentiation, and predisposes the adult prostate to hyperplasia and dysplasia. The mechanism of neonatal estrogenization is not well understood. The present study evaluated transforming growth factor-beta (TGFbeta) in the neonatally estrogenized ventral prostate to determine whether this paracrine/autocrine factor may in part mediate the effects ofestrogen on the developing prostate gland. Immunocytochemistry using antibodies against active TGFbeta1 and its latency-associated peptide localized this molecule to the periductal smooth muscle cells in the developing prostate. Although neonatal estrogenization increased the accumulation of total and active TGFbeta1 in the smooth muscle layer as early as day 6 of life, it was physically separated from the epithelial ducts by a proliferating layer of fibroblasts surrounding the basement membrane. RT-PCR demonstrated that alterations in TGFbeta1 levels were not due to alterations in TGFbeta1 transcription. TGFbeta2 and TGFbeta3 were primarily immunolocalized to differentiating epithelial cells in developing prostates, and this was markedly dampened between days 10-30 after neonatal estrogen exposure. Immunocytochemistry for TGFbeta signaling components revealed that neonatal estrogenization transiently reduced TGFbeta type I receptor levels in the prostate epithelium, but not in stroma, between days 6-15, whereas there was no effect on TGFbeta type II receptor. Levels of the intracellular signal Smad2 (52 kDa) were detected in epithelial cells but were not altered after estrogenization. To analyze the functional status of the TGFbeta signaling pathway, immunocytochemistry was performed for p21(cip-1/waf-1), a cyclin-dependent kinase inhibitor that is inducible by TGFbeta1 in the prostate. Transient nuclear localization of p21(cip-1/waf-1) was normally observed in epithelial cells between days 6-15 and was associated with entry of cells into a terminal differentiation pathway. Neonatal estrogenization prevented this transient expression of p21(cip-1/waf-1). The present findings demonstrate that the TGFbeta signaling system is perturbed at several levels in the estrogenized prostate, which may in part account for the epithelial cell differentiation blockade as well as the proliferation of periductal fibroblasts in this model.

Androgen receptors in two androgen-mediated, sexually dimorphic characters of frogs

The presence/absence of androgen receptors is examined in two sexually dimorphic features of frogs: the nuptial pad and the external oblique muscle. Immunohistochemistry reveals that both males and females possess androgen receptors in these tissues. Males have a higher density of immunopositive nuclei in the oblique muscle than do females. The presence of androgen receptors in both male and female tissues is consistent with results from hormone experiments in which androgen supplements induce the expression of a nuptial pad and enlarge the external oblique muscles in castrated males and ovariectomized females.

Quality of cryopreserved testicular sperm in patients with obstructive and nonobstructive azoospermia

PURPOSE

Sperm retrieved by testicular sperm extraction is routinely used to attempt pregnancy by in vitro fertilization-intracytoplasmic sperm injection. We evaluated the efficacy of cryopreserving testicular sperm collected by testicular sperm extraction at diagnostic biopsy.

MATERIALS AND METHODS

A total of 73 men with obstructive and 42 with nonobstructive azoospermia underwent testicular sperm extraction at diagnostic biopsy. Sperm was retrieved and cryopreserved in all cases of obstruction and in 15 of nonobstructive azoospermia cases. Before freezing we determined sperm count, motility, morphology and viability, and after thawing we assessed sperm motility and viability. In 17 couples a total of 20 cycles of in vitro fertilization-intracytoplasmic sperm injection were performed and fertilization, cleavage and pregnancy rates were determined in cases of obstruction and nonobstruction.

RESULTS

Sperm count and morphology were lower in the testicular biopsies of men with nonobstructive versus obstructive azoospermia. Motility was low or absent in all testicular sperm extraction specimens. Importantly, pre-freeze (63%) and post-thaw (31%) viability was the same in both patient groups. After in vitro fertilization-intracytoplasmic sperm injection using frozen and thawed testicular sperm the fertilization, cleavage, implantation and clinical pregnancy rates were 60, 86, 16 and 50%, respectively. Using cryopreserved sperm we observed no differences in outcome of any in vitro fertilization-intracytoplasmic sperm injection procedure in patients with obstructive versus nonobstructive azoospermia.

CONCLUSIONS

Cryopreservation of testicular sperm provides enough good quality sperm after thawing to result in excellent in vitro fertilization-intracytoplasmic sperm injection outcomes. Cryopreservation does not adversely affect intracytoplasmic sperm injection outcomes, including pregnancy rate. Therefore, we recommend routine testicular sperm extraction and cryopreservation of sperm at testicular biopsy.

Androgen receptors and sexual dimorphisms in the larynx of the bullfrog

As in most anuran amphibians, both male and female bullfrogs (Rana catesbeiana) vocalize. Sex differences in vocalizations in the bullfrog may be due to sex differences in the larynx. We examined the laryngeal muscle to determine whether it possessed androgen receptors and whether there were morphological sexual dimorphisms in the larynx. Using a polyclonal antibody and immunocytochemistry, we found androgen receptors in the laryngeal dilator muscle of both sexes. Males possessed approximately 13% more receptor-positive muscle nuclei than females. We also stained the dilator muscle for the presence of succinate dehydrogenase. Density of staining for the enzyme was significantly greater in male muscle than in female muscle, indicating greater oxidative capacity of muscle in males. This procedure also showed both a significantly greater cross-sectional area for the dilator muscle in males and a greater area for individual fibers. Male muscle consisted almost entirely of fast-twitch oxidative/glycolytic fibers. Female muscle contained a mixture of fast-twitch glycolytic fibers and two subclasses of fast-twitch oxidative/glycolytic fibers. Finally, both the length and width of the entire laryngeal complex and the length and width of the dilator were significantly greater in males than in females. In summary, laryngeal muscle of bullfrogs possessed androgen receptors and is thus likely to be androgen sensitive. Androgens, during development or at adulthood, may be responsible for the anatomic and enzymatic sexual dimorphisms in the larynx.

Neonatal estrogen stimulates proliferation of periductal fibroblasts and alters the extracellular matrix composition in the rat prostate

The purpose of this study was to examine whether changes in extracellular matrix (ECM) molecules are associated with the growth inhibition and differentiation defects of the prostate gland following neonatal exposure to estradiol. Using immunocytochemistry (ICC), laminin and collagen IV were localized to the basement membrane (BM) as well to the basal lamina of the periductal smooth muscle of the control developing prostates. In contrast, fibronectin and collagen III were localized throughout the stromal ECM. Exposure to neonatal estrogen altered the staining profile for specific ECM molecules. In the estrogenized rats, a thick layer of cells negative for laminin and collagen IV was observed adjacent to the BM. Electron microscopy and ICC for alpha-actin, fibronectin, and vimentin identified this multicellular layer of periductal cells as differentiated fibroblasts. Peripheral to these fibroblasts, actin-positive smooth muscle formed a second layer of periductal stromal cells. PCNA labeling showed that estrogen exposure increased the fibroblast proliferation. Because many periductal fibroblasts were positive for estrogen receptor alpha (ER alpha) in estrogenized rats, a direct effect of estradiol on their proliferation is suggested. Gelatinolytic gels revealed that estrogen exposure did not alter the activity of matrix metalloproteinases associated with tissue remodeling during prostate morphogenesis. However, the periductal fibroblast layer in estrogenized prostates was devoid of urokinase- and tissue-plasminogen activator, which may potentially alter the localized proteolysis involved in matrix remodeling. It is proposed that proliferation of a multicellular layer of periductal fibroblasts in estrogenized prostates results in a physical barrier that constrains branching morphogenesis and blocks paracrine communications between smooth muscle and epithelial cells which normally regulate differentiation.

In utero and lactational exposure of the male rat to 2,3,7,8-tetrachlorodibenzo-p-dioxin impairs prostate development. 2. Effects on growth and cytodifferentiation

In the male Holtzman rat, in utero and lactational 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure decreases prostate weight without inhibiting testicular androgen production or decreasing circulating androgen concentrations. Therefore, the present study sought to characterize effects of TCDD exposure on prostate development, from very early outgrowth from the urogenital sinus (Gestation Day [GD] 20) until rapid growth and differentiation are essentially complete (Postnatal Day [PND] 32). Pregnant Holtzman rats were administered a single dose of TCDD (1.0 microgram/kg po) or vehicle on GD 15 and offspring were exposed via placental transfer (GD 20 euthanasia) or placental and subsequent lactational transfer until euthanasia (if before PND 21) or weaning. Results show that the prostatic epithelial budding process was impaired by in utero TCDD exposure, as evidence by significant decreases in the number of buds emerging from dorsal, lateral, and ventral aspects of the GD 20 urogenital sinus. Ventral prostate cell proliferation index was significantly decreased on PND 1 but was similar to or higher than control at later times, whereas apoptosis was an extremely rare event in ventral prostates from both control and TCDD-exposed animals. Delays were noted in the differentiation of pericordal smooth muscle cells and luminal epithelial cells. In addition, ventral prostates from approximately 40% of TCDD-exposed animals examined on PNDs 21 and 32 exhibited alterations in the histological arrangement of cell types that could not be explained by a developmental delay. Compared to controls, these ventral prostates exhibited a disorganized, hyperplastic epithelium containing fewer luminal epithelial cells and an increased density or continuous layer of basal epithelial cells, as well as thicker periductal smooth muscle sheaths. In addition, in ventral prostates from TCDD-exposed animals, the intensity of androgen receptor staining was relatively low in the central and distal epithelium, and the number of androgen receptor-positive cells was relatively high in the periductal stroma. These data suggest that in utero and lactational TCDD exposure interferes with prostate development by decreasing very early epithelial growth, delaying cytodifferentiation, and, in the most severely affected animals, producing alterations in epithelial and stromal cell histological arrangement and the spatial distribution of androgen receptor expression that may be of permanent consequence.

Distribution of androgen receptor-immunoreactive cells in the quail forebrain and their relationship with aromatase immunoreactivity

The distribution of androgen receptor-like immunoreactive (AR-ir) cells in the quail brain was analyzed by immunocytochemistry with the use of the affinity-purified antibody PG-21-19A raised against a synthetic peptide representing the first 21 N-terminal amino acids of the rat and human AR. This antibody is known to bind to the receptor in the absence as well as in the presence of endogenous ligands, and it was therefore expected that a more complete and accurate characterization of AR-ir cells would be obtained in comparison with previous studies using an antibody that preferentially recognizes the occupied receptor. Selected sections were double labeled for aromatase (ARO) by a technique that uses alkaline phosphatase as the reporter enzyme and Fast blue as the chromogen. AR-ir material was detected in the nucleus of cells located in a variety of brain areas in the preoptic region and the hypothalamus including the medial preoptic (POM), the supraoptic, the paraventricular (PVN), and the ventromedial (VMN) nuclei, but also in the tuberculum olfactorium, the nucleus accumbens/ventral striatum, the nucleus taeniae, the tuberal hypothalamus, the substantia grisea centralis (GCt), and the locus ceruleus. Cells exhibiting a dense AR-ir label were also detected in the nucleus intercollicularis. Preincubation of the primary antibody with an excess of the synthetic peptide used for immunization completely eliminated this nuclear staining. A significant number of AR-ir cells in the POM, VMN, PVN, and tuberal hypothalamus also contained ARO-ir material in their cytoplasm. These data confirm and extend previous studies localizing AR in the avian brain, and raise questions about the possible regulation by androgens of the metabolizing enzyme aromatase.

Development, progression, and androgen-dependence of prostate tumors in probasin-large T antigen transgenic mice: a model for prostate cancer

Probasin (PB) gene product is prostate-specific, epithelial cell in origin, and androgen-regulated. A large 12-kb promoter fragment of the PB gene (LPB) was linked to the simian virus 40 (SV40) large T antigen (Tag) deletion mutant (that removes the expression of the small t antigen) to deliver consistently high levels of transgene expression to the transgenic mouse prostate. Seven male founders, their male offspring, and all the male offspring from two female founders developed at least prostatic epithelial cell hyperplasia by 10 weeks of age, indicating that the incidence of transformation was 100%. Tumorigenesis in the LPB-Tag animals progressed in a manner similar to that observed in the human prostate. Initially, multifocal proliferating lesions were detected in the prostatic epithelium, which continued to progress into hyperplasia involving the entire epithelium and then low-grade dysplasia. Reactive stromal proliferation was induced and continued to develop throughout the progression to high-grade dysplasia, carcinoma in situ, and adenocarcinoma. Immunohistochemical studies indicated that most stromal cells stained positively for both androgen receptor and smooth muscle alpha-actin, suggesting that stromal overgrowth largely represented mesenchymal cells that had differentiated into smooth muscle cells. Epithelial cell transformation was accompanied by the down-regulation of differentiated function, as suggested by the loss of dorsolateral prostate-specific secretory proteins. Tumor growth was regarded as androgen-dependent because tumors regressed in animals castrated at 11 weeks of age, and androgen treatment restored both epithelial/stromal cell ratio and tumor growth. Furthermore, small populations of prostatic epithelial cells in castrated animals continued to proliferate, suggesting the potential for androgen-independent growth. Although prostatic metastasis to other organs was not observed, local invasion was detected. In summary, the LPB-Tag animal model is unique in that it is the only model generated with the Tag alone, thereby eliminating any influences of the small t antigen on prostate tumor formation. Moreover, this model undergoes molecular changes similar to those found in human prostate including: (a) the multi-focal nature of tumorigenesis, (b) the progressive histopathologic changes from low- to high-grade dysplasia similar to human prostatic intraepithelial neoplasia, (c) stimulation of reactive stromal proliferation, and (d) the androgen-dependent growth of the primary tumor. Thus, the LPB-Tag prostate tumor model will be useful for studying the sequential mechanisms underlying the development of multistep tumorigenesis.

Development, progression, and androgen-dependence of prostate tumors in probasin-large T antigen transgenic mice: a model for prostate cancer

Probasin (PB) gene product is prostate-specific, epithelial cell in origin, and androgen-regulated. A large 12-kb promoter fragment of the PB gene (LPB) was linked to the simian virus 40 (SV40) large T antigen (Tag) deletion mutant (that removes the expression of the small t antigen) to deliver consistently high levels of transgene expression to the transgenic mouse prostate. Seven male founders, their male offspring, and all the male offspring from two female founders developed at least prostatic epithelial cell hyperplasia by 10 weeks of age, indicating that the incidence of transformation was 100%. Tumorigenesis in the LPB-Tag animals progressed in a manner similar to that observed in the human prostate. Initially, multifocal proliferating lesions were detected in the prostatic epithelium, which continued to progress into hyperplasia involving the entire epithelium and then low-grade dysplasia. Reactive stromal proliferation was induced and continued to develop throughout the progression to high-grade dysplasia, carcinoma in situ, and adenocarcinoma. Immunohistochemical studies indicated that most stromal cells stained positively for both androgen receptor and smooth muscle alpha-actin, suggesting that stromal overgrowth largely represented mesenchymal cells that had differentiated into smooth muscle cells. Epithelial cell transformation was accompanied by the down-regulation of differentiated function, as suggested by the loss of dorsolateral prostate-specific secretory proteins. Tumor growth was regarded as androgen-dependent because tumors regressed in animals castrated at 11 weeks of age, and androgen treatment restored both epithelial/stromal cell ratio and tumor growth. Furthermore, small populations of prostatic epithelial cells in castrated animals continued to proliferate, suggesting the potential for androgen-independent growth. Although prostatic metastasis to other organs was not observed, local invasion was detected. In summary, the LPB-Tag animal model is unique in that it is the only model generated with the Tag alone, thereby eliminating any influences of the small t antigen on prostate tumor formation. Moreover, this model undergoes molecular changes similar to those found in human prostate including: (a) the multi-focal nature of tumorigenesis, (b) the progressive histopathologic changes from low- to high-grade dysplasia similar to human prostatic intraepithelial neoplasia, (c) stimulation of reactive stromal proliferation, and (d) the androgen-dependent growth of the primary tumor. Thus, the LPB-Tag prostate tumor model will be useful for studying the sequential mechanisms underlying the development of multistep tumorigenesis.

Estrogen receptor-beta messenger ribonucleic acid ontogeny in the prostate of normal and neonatally estrogenized rats

Neonatal exposure to estrogens permanently alters rat prostate growth and epithelial differentiation leading to prostatic dysplasia on aging. The effects are lobe-specific, with the greatest response observed in the ventral lobe. Recently, a novel estrogen receptor (ER) complementary DNA was cloned from the rat prostate and termed ER-beta (ER beta) due to its high homology with the classical ER alpha. The protein possesses high affinity for 17beta-estradiol, indicating that ER beta is an alternate molecule for mediating estrogenic effects. Importantly, ER beta messenger RNA (mRNA) was localized to rat prostatic epithelial cells, which contrasts with the stromal localization of ER alpha in the rat prostate. The present study was undertaken to determine the ontogeny of ER beta mRNA expression in the rat prostate lobes and to examine the effects of early estrogen exposure on prostatic ER beta expression. Male rat pups were given 25 microg estradiol or oil on days 1, 3, and 5; were killed on day 1, 3 (oils only), 6, 10, 30, or 90; and prostate lobes were frozen. Longitudinal sections were processed for in situ hybridization using an 35S-labeled antisense mRNA probe corresponding to a 400-bp EcoRI-AccI fragment in the 5' untranslated region of rat ER beta complementary DNA. Image analysis was used to quantitate silver grains. In addition, total RNA was isolated from the ventral prostate (VP) and used for semiquantitative RT-PCR. Results from in situ hybridization revealed that at birth, ER beta was equivalently expressed at low levels in both mesenchymal and epithelial cells in oil-treated rats. From day 1 onwards, expression in all stromal cells slowly and significantly declined, so that in the control adult prostate, stromal ER beta mRNA was slightly above background. In the oil-treated control rats, epithelial ER beta mRNA increased to moderate levels between days 6-10 in the VP and days 10-15 in the dorsal and lateral lobes as cells began differentiation and ducts lumenized. A further significant increase in ER beta message was observed at day 30, which indicates that full epithelial ER beta expression may require the completion of functional differentiation. By day 90, expression levels were maximal and similar between the lobes. RT-PCR substantiated this developmental increase in ER beta between days 1-90. Neonatal exposure to estrogens did not have an immediate effect on prostatic ER beta mRNA levels as determined by in situ hybridization and RT-PCR. However, the marked increase in epithelial cell expression at day 30 observed in the control VP was dampened in the VP of animals exposed neonatally to estrogens. By day 90, the VP of estrogenized rats possessed low ER beta message levels compared with the high expression in oil controls. In contrast, the dorsal and lateral lobes of neonatally estrogenized rats possessed high levels of ER beta mRNA at day 90, equivalent to controls. The present data demonstrate that ER beta mRNA expression in the rat prostate is developmentally regulated, and that neonatal estrogen can affect this expression in the adult VP. Because the effect of neonatal estrogens was not immediate, the data imply that early estrogen exposure may not directly autoregulate ER beta expression, and suggests that the adult effects on ER beta mRNA expression may be indirect. The differences in ER beta mRNA imprinting in the separate lobes may account for or reflect the lobe-specific neonatal estrogen imprints previously observed in the rat prostate.

Image analysis of androgen receptor immunostaining in prostate cancer accurately predicts response to hormonal therapy

PURPOSE

Immunostaining for androgen receptor in prostate tumor specimens has revealed that the majority of primary and advanced stage cancers are positive for this regulatory transcription factor. Consequently, its use as a marker for tumor behavior and therapeutic response has been discounted. However, past reports have noted significant heterogeneity of androgen receptor immunostaining between prostate tumor cells in contrast to staining homogeneity in normal epithelium, which indicates that variability in androgen receptor content may exist within certain tumor specimens. To analyze this phenomenon more thoroughly and to determine whether this variability possesses clinical correlates, androgen receptor immunostaining profiles within androgen receptor positive prostate tumor specimens were categorized using an image analysis based system.

MATERIALS AND METHODS

Tumor specimens were obtained before hormone therapy from 44 patients with advanced stage prostate cancer and 4 with early stage disease who later had progression. Response to antiandrogen therapy and survival was monitored. Paraffin embedded tumor sections were processed for immunocytochemistry and stained for androgen receptor. A Quantimet image analysis system was used to analyze nuclear immunostaining for androgen receptor and Receptogram patterns were established for each specimen based on univariate distributions of nuclear receptor content and concentration.

RESULTS

Data revealed that 17 of 18 responders to hormone therapy possessed type 1 (15) or type 3 (2) Receptograms, which are characterized by a unimodal peak or multimodal peaks within a narrow concentration range. Of the 17 cases that stabilized following therapy 16 had type 3 Receptograms and 1 was characterized as type 1. In contrast, all 13 patients in whom endocrine treatment failed had either type 2 or 4 Receptograms, which are characterized by a highly skewed or bimodal androgen receptor distribution. Positive and negative predictive values for this assay were 100 and 93%, respectively. In addition, the type 1/3 Receptogram patterns were correlated with longer mean survival.

CONCLUSIONS

Image analysis of prostate cancer androgen receptor immunostaining with a pattern oriented approach for response is capable of accurately predicting response to hormone therapy in patients with advanced stage disease. Application of this analytic scheme may assist the clinician with therapeutic management of advanced prostate cancer.

Age-dependent changes in androgen receptor immunoreactivity in motoneurons of the spinal nucleus of the bulbocavernosus of male rats

Androgen receptor (AR) immunoreactivity was examined in androgen-sensitive motoneurons of the spinal nucleus of the bulbocavernosus (SNB) in young and old male rats by immunohistochemistry using the polyclonal antibody, PG21. In young animals, intense AR immunoreactivity was confined to the cell nucleus, but not in the nucleolus of SNB motoneurons. In old animals, both the intensity of AR immunoreactivity in the nuclei and number of AR immunoreactive nuclei of the SNB motoneurons were significantly reduced. Plasma levels of testosterone in old animals were significantly smaller than those in young ones. Age-dependent changes both in AR expression of SNB motoneurons and plasma levels of androgen seem to correlate with the aging of the SNB system.

Expression of epidermal growth factor and androgen receptors in ovarian cancer

Ovarian cancer is the second most common malignancy of the female reproductive tract. Approximately 50% of ovarian cancers have elevated levels of epidermal growth factor receptor (EGFR). This overexpression is correlated with a poor prognosis for patient survival. Ovarian cancers also express a number of sex steroid receptors. The androgen receptor (AR) is the predominant sex steroid receptor and is expressed in over 80% of ovarian cancers. We investigated whether a relationship exists between EGFR and AR in ovarian cancer. Sixty serous cystadenocarcinomas were analyzed for their relative levels of EGFR and AR by Western blot analysis. Data were analyzed by Student's t test and linear regression analysis for statistical significance. More than 98% of the tumors expressed detectable levels of EGFR, while 65% of the tumors expressed detectable levels of AR. The levels of EGFR (mean +/- SEM) were found to be significantly (P < 0.01) higher in AR+ (516 +/- 15) than in AR- (304 +/- 57) tumors. EGFR levels significantly correlated to AR levels (r = 0.49, P < 0.001). These results demonstrate an association between EGFR and AR levels in ovarian cancer. Whether this association represents a causal or a casual relationship remains to be determined.

Neonatal estrogen exposure up-regulates estrogen receptor expression in the developing and adult rat prostate lobes

Neonatal exposure to estrogens results in permanent imprints of the rat prostate gland. To delineate the direct target of estrogen action within that tissue, the present study examined estrogen receptor (ER) expression by immunocytochemistry and in situ hybridization. ER were confined to mesenchymal cells in the urogenital sinus and proximal regions of the budding prostate lobes of newborn control rat prostates, and this expression declined after morphogenesis. Exposure to estradiol benzoate on days 1, 3, and 5 resulted in induction of ER expression in periductal smooth muscle cells from the proximal regions out to the distal tips of the developing prostate lobes. This ER expression was associated with the appearance of ER messenger RNA in those cells; thus, it was concluded that the up-regulation of ER by estrogens is mediated at the message level. Autoregulation of ER expression was next examined in adult prostates that had been exposed to oil or estrogens neonatally. Day 70 rats were castrated and given testosterone with or without estradiol for 7 days before death. Estrogen exposure in adulthood induced low levels of epithelial cell ER in the lateral lobe. Neonatal estrogenization increased the sensitivity of lateral lobe epithelial cells to this autoregulation, as the incidence and intensity of ER immunostaining were markedly increased. No autoinduction of ER was observed in adult ventral or dorsal prostatic lobes. From the present study we conclude that smooth muscle cells are the targets of estrogen action in the developmentally estrogenized prostate and that estrogen amplifies its own effects through auto-up-regulation of ER. In addition, lateral lobe epithelial cells are sensitive to estrogen up-regulation of ER, which may in part account for the lobe-specific effects observed after neonatal estrogenization of the prostate gland.

Co-localization of androgen receptor and nitric oxide synthase in the ventral premammillary nucleus of the newborn rat: an immunohistochemical study

The distribution of the neuronal nitric oxide synthase (nNOS), androgen receptor (AR), estrogen receptor (ER) and aromatase (ARO) was studied in the dorsal and ventral premammillary nuclei (PMd and PMv) of the newborn rat by immunohistochemistry. In the intact male pups, nNOS immunoreactivity (-IR) was present both in the PMd and the PMv, while AR-IR was detected only in the PMv. On the other hand, ER-IR and ARO-IR were scarcely encountered in the both PMd and PMv. By double immunostaining of nNOS and AR, all the nNOS-IR cells in the PMv were revealed to contain AR-IR. In the intact female pups, nNOS-IR was present in the both PMd and PMv, but neither ER-, nor ARO-IR were detected in the PM region. In the PMv of the intact female rat, no AR-IR was detected at 6 days of age, while it was detected as only a faint staining within 12 h after birth. When the male pups were castrated neonatally, no AR-IR was detected in the PMv. Subcutaneous injections of 5alpha-dihydrotestosterone (DHT) induced strong AR-IR in the castrated male and the intact female pups. On the contrary, the intensity of nNOS-IR stayed unchanged among these animals. Neonatal androgen and nitric oxide has been considered important to brain development. Moreover, involvement of the PMv in aggressive and mating behavior of male animals has been reported. Together with the fact that the AR-IR and nNOS-IR were found in the same neurons in the PMv, involvement of this nucleus in masculinization of the brain by non-aromatizable androgen is postulated.

Ontogeny of androgen receptor-like immunoreactivity in the reproductive tract of male Monodelphis domestica

The distribution of nuclear androgen receptor-like immunoreactivity was studied in the reproductive tract of the developing and adult gray short-tailed Brazilian opossum (Monodelphis domestica), using the well-characterized rabbit polyclonal androgen receptor antibody, PG21. Androgen receptor-like immunoreactivity was first detected on the fifth day of postnatal age, in the mesenchymal tissues of the ductus deferens, gubernaculum testis, inguinal, and scrotal areas; the urogenital sinus; and the genital tubercle. Androgen receptor-like immunoreactivity was first seen in the interstitial cells of the epididymis at 45 days of age; the testes developed androgen receptor-like immunoreactivity at 60 days of age. The epithelium of prostatic glands contained androgen receptor-like immunoreactivity only in the adult. The presence of androgen receptor-like immunoreactivity during development correlated well with the known androgen dependence of the differentiation of most reproductive organs.

Use of PG-21 immunocytochemistry to detect androgen receptors in the songbird brain

The avian song control system is an excellent model in which to study the effects of gonadal steroid hormones on neural and behavioral plasticity. Several of the brain regions that control song behavior concentrate androgens and/or estrogens. Investigations of the distribution and regulation of androgen receptors have been limited by the lack of a reliable immunocytochemical method to detect androgen receptors in the songbird brain. We describe a protocol by which the PG-21 polygonal antibody to the rat androgen receptor can be used to label androgen receptor-containing cells in the songbird brain. By treating songbirds of several species with testosterone 90 min before sacrifice and by using relatively low concentrations (0.5 0.75 microg/ml) of PG-21 antibody to reduce nonspecific background staining, we were able to obtain strong specific labeling of cell nuclei in androgen-sensitive brain regions. This technique will facilitate the study of the role of androgens in mediating neural plasticity in the avian brain. Testosterone pretreatment may also facilitate the use of this antibody to label androgen receptors in tissues from a wide array of nonmammalian species.

Autoregulation of androgen receptor protein and messenger RNA in rat ventral prostate is protein synthesis dependent

In order to investigate the role of protein synthesis in the testosterone regulation of androgen receptor (AR) levels, in vivo studies were undertaken using the ventral prostate gland from adult male rats castrated 24 h previously. Our results showed that testosterone (400 microg/100 g body weight) increased nuclear AR binding 1 h after administration, whereas the protein synthesis inhibitor cycloheximide (400 microg/100 g body weight) by itself did not alter AR binding. However, concomitant administration of testosterone and cycloheximide blocked the testosterone-induced nuclear AR accumulation after 1 h. To determine if changes in AR binding reflected changes in AR protein levels, immunocytochemical studies were conducted on individually dissected ventral prostatic ducts. Castration 24 h previously induced a decrease in nuclear AR immunostaining when compared to intact animals. Testosterone treatment restored the nuclear staining, particularly at the distal tips of the prostatic ducts. Cycloheximide alone did not change AR immunostaining when compared to castrated vehicle-treated rats, yet it significantly decreased the nuclear AR staining induced by testosterone. Our results suggest that AR is being newly synthesized during testosterone treatment. To determine if the effect of testosterone in the regulation of the AR protein was ultimately due to changes at the messenger RNA (mRNA) levels, steady-state AR mRNA levels were measured. Northern blot analysis of poly A+ mRNA preparations revealed that androgen withdrawal for 24 h increased AR mRNA and that testosterone treatment for 1 h did not alter these increased AR mRNA levels. The inhibition of protein synthesis by cycloheximide did not change AR mRNA, but, when cycloheximide was administered in conjunction with testosterone, AR mRNA levels were significantly decreased. In an attempt to relate these responses to changes in transcriptional activity, the transcription inhibitor actinomycin D was administered in vivo. Whereas simultaneous administration of testosterone and cycloheximide modified AR mRNA and AR protein levels, concomitant administration of testosterone with actinomycin D did not alter these levels. It is therefore unlikely that testosterone modifies the transcription of AR mRNA within 1 h after its administration. Collectively, these results suggest that protein synthesis is involved in the mechanism of testosterone-promoted AR regulation. This protein synthesis-dependent mechanism may be involved in the regulation of the stability and/or the translation of AR mRNA in the prostate.