Evidence that epithelial and mesenchymal estrogen receptor-alpha mediates effects of estrogen on prostatic epithelium

Gene expression correlation analysis predicts involvement of high- and low-confidence risk genes in different stages of prostate carcinogenesis

BACKGROUND

Whole genome association studies have identified many loci associated with the risk of prostate cancer (PC). However, very few of the genes associated with these loci have been related to specific processes of prostate carcinogenesis. Therefore I inferred biological functions associated with these risk genes using gene expression correlation analysis.

METHODS

PC risk genes reported in the literature were classified as having high (P<10(-6)), medium (P<10(-4)), or low (P<10(-2)) statistical confidence. Correlation coefficients of the expression levels between the risk genes and other genes in cancerous prostates samples were compared against those in normal prostates using a microarray dataset from Gene Expression Omnibus.

RESULTS

Overall, significant decrease of correlations in PC was observed between the levels of expression of the high-confidence genes and other genes in the microarray dataset, whereas correlation between low-confidence genes and other genes in PC showed smaller decrease. Genes involved in developmental processes were significantly correlated with all risk gene categories. Ectoderm development genes, which may be related to squamous metaplasia, and genes enriched in fetal prostate stem cells (PSCs) showed strong association with the high-confidence genes. The association between the PSC genes and the low-confidence genes was weak, but genes related to neural system genes showed strong association with low-confidence genes.

CONCLUSIONS

The high-confidence risk genes may be associated with an early stage of prostate carcinogenesis, possibly involving PSCs and squamous metaplasia. The low-confidence genes may be involved in a later stage of carcinogenesis.

The association between the rs2234693 and rs9340799 estrogen receptor alpha gene polymorphisms and risk factors for cardiovascular disease: a review

Although estrogen is primarily thought of as the hormone involved in female reproduction, it also plays a role in many additional physiological and pathological processes. Recent studies have demonstrated an association between estrogen and clustered risk factors for cardiovascular disease (CVD), such as lipid and glucose metabolism and obesity-related phenotypes, as well as occurrence and severity of CVD. Evidence suggesting a genetic basis for this link is accumulating. Several polymorphisms of the estrogen receptor (ER) alpha (ESR1) gene exist that may influence the impact of estrogen, leading to clinically relevant phenotypes. Based on the relationship ERS1 seems to exhibit with CVD risk factors, these polymorphisms may play a role in the mediation of vasoprotective effects, modulation of cardiovascular physiology, and development of risk factors for CVD. The two most frequently studied polymorphisms located in ESR1 are often identified by their restriction endonucleases Pvull (rs2234693) and Xbal (rs9340799). ln this review, we have evaluated and summarized the results of studies involving rs2234693 and rs9340799 and clustered risk factors accompanying development of CVD. Despite inconsistent findings, together these studies provide some support for a relationship between polymorphisms in ESR1 and risk factors for CVD. These summarized findings do not yet support inclusion of ESR1 genotypes in genetic testing algorithms for predisposition to CVD, but they do indicate that further investigation into the potential connection between ESR1 and risk factors for CVD is warranted.

Effect of combined hormonal and insulin therapy on the steroid hormone receptors and growth factors signalling in diabetic mice prostate

Diabetes causes harmful effects on prostatic morphology and function. However, there still are doubts about the occurrence of various diseases in the prostate, as well as abnormal angiogenesis in relation to diabetes. Thus, the aim of this study was to correlate and quantify the level of the steroid hormone receptors and the angiogenic and antiangiogenic factors in non-obese diabetic mice (Nod) after combined hormonal and insulin therapy. Sixty mice were divided into six groups after 20 days of diabetes: the control group received 0.9% NaCl, as did the diabetic group. The diabetic-insulin group received insulin, the diabetic-testosterone group received testosterone cypionate, the diabetic-oestrogen group received 17β-oestradiol, and the diabetic-insulin-testosterone-oestrogen group received insulin, testosterone and oestrogen simultaneously. After 20 days, the ventral lobe was processed for immunocytochemical and hormonal analyses. The results showed that the lowest serum testosterone and androgen receptor levels were found in the diabetic group and the highest testosterone and androgen receptor levels in the diabetic-insulin-testosterone-oestrogen group. The serum oestrogen level and its receptor showed changes opposite to those of testosterone and its receptor. The endostatin reactivity was mainly decreased in diabetic mice. The greatest IGFR-1 and VEGF reactivities occurred in diabetic mice. Thus, diabetes led to the prostatic hormonal imbalance, affecting molecular dynamics and angiogenesis in this organ. Combined insulin and steroid hormone therapy partially restored the hormonal and angiogenic imbalance caused by diabetes.

Oestrogens and spermatogenesis

The role of oestrogens in male reproductive tract physiology has for a long time been a subject of debate. The testis produces significant amounts of oestrogenic hormones, via aromatase, and oestrogen receptors (ERs)alpha (ESR1) and ERbeta (ESR2) are selectively expressed in cells of the testis as well as the epididymal epithelium, depending upon species. This review summarizes the current knowledge concerning the presence and activity of aromatase and ERs in testis and sperm and the potential roles that oestrogens may have in mammalian spermatogenesis. Data show that physiology of the male gonad is in part under the control of a balance of androgens and oestrogens, with aromatase serving as a modulator.

ERbeta: recent understanding of estrogen signaling

The discovery of a second estrogen receptor, ERbeta, and the finding that 5alpha-androstane-3beta,17beta-diol (3betaAdiol) strongly binds to ERbeta, have opened up a new aspect of estrogen signaling. Some of the major shifts in our understanding come from finding ERbeta in tissues which do not express ERalpha but are estrogen-responsive; these were called sites of 'indirect estrogen action'. Two key sites that fall into this category are the brain and the prostate. Studies of ERbeta in the past 10 years have led us to hypothesize that estrogen signaling depends on the balance between ERalpha and ERbeta, and that inadequate predominance of one or the other isoform could lead to disease.

Effect of transforming growth factor α overexpression on urogenital organ development in mouse

Transforming growth factor-α (TGFα) promotes cell proliferation by binding to the epidermal growth factor receptor (EGFR). TGFα and EGFR overexpression have been reported in various human cancers. However, whether TGFα induces cancer by itself is unknown in urogenital organs. To investigate whether TGFα overexpression induces carcinogenesis in urogenital organs, we analyzed the phenotypes of urogenital organs in male TGFα transgenic (TG) mice of the CD1 strain. Urogenital organs including the kidney, bladder, prostate, seminal vesicles, testes, and epididymis were isolated from 4- to 48-week-old TGFα TG and wild-type (WT) CD1 mice. Prostates were separated into anterior prostate (AP), dorsolateral prostate (DLP), and ventral prostate (VP). Neither tumor formation nor epithelial hyperplasia was observed in the TGFα TG mouse urogenital organs that we have investigated. Histopathologically, in prostate, we found an increased number of p63-positive basal epithelial cells in the TGFα TG mice AP and DLP. There was no morphological change in the stromal component, such as hypercellular stroma or fibrosis. However, bladder weight was greater in TGFα TG mice than that in WT mice, and distended bladders were observed macroscopically in 19 of 20 TGFα TG mice over 20 weeks of age. Ki67 labeling index was increased significantly in the TGFα TG mouse urethral epithelium, whereas neither epithelial hyperplasia nor hypertrophy was observed. In conclusion, our results suggest that TGFα overexpression in mouse urogenital organs alone may not be responsible for tumor formation and epithelial hyperplasia, but is involved in bladder outlet obstruction.

Proliferative, structural and molecular features of the Mdx mouse prostate

The prostate is fundamental to the male reproductive process, and the stroma-epithelium interaction has an important role in prostate maintenance. Studies suggest that dystroglycan (DG) plays a role in cancer development in various organs. Thus, the aims of this work were to characterize morphological and proliferative features of the prostatic stroma and epithelium of mdx mice; to verify the immunolocalization of the α and β DG, IGF-1 and laminin α3 receptors; and to relate those structural and molecular events to prostate pathogenesis and to verify the viability of this experimental model in prostate studies. Thirty male mice (mdx and C57BL10/Uni) were divided into control and mdx groups. Samples from the ventral prostate were collected for immunological, Western Blotting, transmission electron microscopy and morphometric analyses. Oestradiol and testosterone measurements were verified. The results showed diminished testosterone and increased oestradiol levels in the mdx group. Atrophied cells and hypertrophied stroma were seen in the mdx mice. Weak α and β DG and laminin α3 immunolocalization was demonstrated in the mdx group. Intense insulin-like growth factor receptor α-1 (IGFRα-1) localization was identified in the mdx animals. Thus, mdx animals showed changes in molecular and structural integrity and proliferation signals, leading to glandular homoeostasis imbalance, and compromise of prostate function. Also, the steroid hormone imbalance and the increased IGF-1 receptor level detected in mdx mice could be considered as a crucial factor in the pathogenesis of prostatic disorders.

Deletion of androgen receptor in the smooth muscle of the seminal vesicles impairs secretory function and alters its responsiveness to exogenous testosterone and estradiol

The seminal vesicles (SVs), like much of the male reproductive tract, depend on androgen-driven stromal-epithelial interactions for normal development, structure, and function. The primary function of the SVs is to synthesize proteins that contribute to the seminal plasma and this is androgen dependent. However, the cell-specific role for androgen action in adult SVs remains unclear. This study analyzed the SV in mice with targeted ablation of androgen receptors specifically in smooth muscle cells (PTM-ARKO) to determine in vivo whether it is androgen action in a subset of the SV stroma, the smooth muscle cells, that drives epithelial function and identity. These mice have significantly smaller SVs in adulthood with less smooth muscle and reduced epithelial cell height. Less epithelial cell proliferation was observed in adult PTM-ARKO SVs, compared with controls, and production of seminal proteins was reduced, indicating global impairment of epithelial cell function in PTM-ARKO SVs. None of these changes could be explained by altered serum testosterone or estradiol concentrations. We also demonstrate altered SV responsiveness to exogenous testosterone and estradiol in PTM-ARKO mice, indicating that smooth muscle androgen receptors may limit the SV epithelial proliferative response to exogenous estrogens. These results therefore demonstrate that the smooth muscle cells play a vital role in androgen-driven stromal-epithelial interactions in the SV, determining epithelial cell structure and function as well as limiting the SV epithelial proliferative response to exogenous estrogens.

Aromatase and regulating the estrogen:androgen ratio in the prostate gland

Although androgens and estrogens both play significant roles in the prostate, it is their combined action--and specifically their balance--that is critically important in maintaining prostate health and tissue homeostasis in adulthood. In men, serum testosterone levels drop by about 35% between the ages of 21 and 85 while estradiol levels remain constant or increase. This changing androgen:estrogen (T:E) ratio has been implicated in the development of benign and malignant prostate disease. The production of estrogens from androgens is mediated by the aromatase enzyme, the aberrant expression of which plays a critical role in the development of malignancy in a number of tissues. The normal prostate expresses aromatase within the stroma, while there is an induction of epithelial expression in malignancy with altered promoter utilisation. This may ultimately lead to an altered T:E ratio that is associated with the development of disease. The role of estrogen and the T:E balance in the prostate is further complicated by the differential actions of both estrogen receptors, alpha and beta. Stimulation of ERalpha leads to aberrant proliferation, inflammation and pre-malignant pathology; whereas activation of ERbeta appears to have beneficial effects regarding cellular proliferation and a putative protective role against carcinogenesis. Overall, these data reveal that homeostasis in the normal prostate involves a finely tuned balance between androgens and estrogens. This has identified estrogen, in addition to androgens, as integral to maintaining normal prostate health, but also as an important mediator of prostate disease.

Estrogens and bladder outlet obstruction

Increasing evidence indicates a direct interrelationship between benign prostatic hyperplasia and chronic non-bacterial prostatic inflammation in the development of human voiding dysfunction in aging male, which gradually transforms to bladder outlet obstruction (BOO). Increased prevalence of BOO along with the aging process further suggests that estrogen or more precisely decreased androgen to estrogen ratio in serum is involved in the pathogenesis of BOO. In this review, we will analyze the hormonal causes, clinical relevance, and biologically relevant estrogen-modulated animal models potential for BOO study. In light of the data presented in this review, it becomes apparent that direct inhibition of estrogen action may provide important pharmaceutical treatment of the BOO.

Estrogen receptor-beta activated apoptosis in benign hyperplasia and cancer of the prostate is androgen independent and TNFalpha mediated

Prostate cancer (PCa) and benign prostatic hyperplasia (BPH) are androgen-dependent diseases commonly treated by inhibiting androgen action. However, androgen ablation or castration fail to target androgen-independent cells implicated in disease etiology and recurrence. Mechanistically different to castration, this study shows beneficial proapoptotic actions of estrogen receptor-beta (ERbeta) in BPH and PCa. ERbeta agonist induces apoptosis in prostatic stromal, luminal and castrate-resistant basal epithelial cells of estrogen-deficient aromatase knock-out mice. This occurs via extrinsic (caspase-8) pathways, without reducing serum hormones, and perturbs the regenerative capacity of the epithelium. TNFalpha knock-out mice fail to respond to ERbeta agonist, demonstrating the requirement for TNFalpha signaling. In human tissues, ERbeta agonist induces apoptosis in stroma and epithelium of xenografted BPH specimens, including in the CD133(+) enriched putative stem/progenitor cells isolated from BPH-1 cells in vitro. In PCa, ERbeta causes apoptosis in Gleason Grade 7 xenografted tissues and androgen-independent cells lines (PC3 and DU145) via caspase-8. These data provide evidence of the beneficial effects of ERbeta agonist on epithelium and stroma of BPH, as well as androgen-independent tumor cells implicated in recurrent disease. Our data are indicative of the therapeutic potential of ERbeta agonist for treatment of PCa and/or BPH with or without androgen withdrawal.

PTPIP51 mRNA and protein expression in tissue microarrays and promoter methylation of benign prostate hyperplasia and prostate carcinoma

BACKGROUND

Protein tyrosine phosphatase interacting protein 51 (PTPIP51) shows a tissue-specific expression pattern and is associated with cellular differentiation and apoptosis in several mammalian tissues. Overexpression of the full-length protein enhances apoptosis. It is also expressed in various carcinomas. In this study the expression of PTPIP51 and its in vitro interaction partners was investigated in human benign prostate hyperplasia (BPH) and in prostate carcinoma (PCa).

METHODS

Tissue microarrays of human BPH and PCa were analyzed by immunohistochemistry. For polymerase chain reaction (PCR), cryo samples of BPH and PCa were used. Bisulfite DNA treatment, followed by sequencing of PCR products was performed in order to analyze CpGs methylation within the promoter region of the PTPIP51 gene.

RESULTS

PTPIP51 mRNA and protein expression was detected in prostatic epithelia of BPH and in tumor cells of PCa, respectively, and within smooth muscle cells of the stromal compartment. A stronger expression was present in nerve fibers, particularly in PCa, in immune cells and in smooth muscle and endothelial cells of vessels of BPH and PCa. On mRNA levels, a slightly elevated expression of PTPIP51 was observed in the PCa group as tested by real-time quantitative PCR analyses. Methylation experiments revealed that at least 70% of methylated CpGs in the CpG island of the PTPIP51 gene promoter region were identified in BPH samples. In contrast, a loss of methylation has been found in the PCa group.

CONCLUSION

The promoter methylation status of PTPIP51 seems to influence the expression of PTPIP51, which was seen as elevated in the PCa.

Oestrogen imprinting causes nuclear changes in epithelial cells and overall inhibition of gene transcription and protein synthesis in rat ventral prostate

Oestrogen exposure during the early post-natal period affects male growth, physiology, and susceptibility to disease in adult life. The prostate gland is susceptible to this oestrogen imprinting, showing a reduced expression of the androgen receptor and inability to respond to androgen stimulus. In this context, we decided to study key signalling regulators of ventral prostate (VP) functioning after early postnatal exposure to high-dose oestrogen. Our results showed a decrease of mTOR phosphorylation and its direct downstream target 4EBP. It is known that mTOR-induced signalling is a pivotal pathway of cell metabolism, which is able to control gene transcription and protein synthesis. We then decided to investigate other indicators of a reduced metabolism in the oestrogenized prostate, and found that the luminal epithelial cells were shorter, less polarized and had smaller nuclei containing more compacted chromatin, suggesting that a general mechanism of regulating gene expression and protein synthesis could be installed in the epithelium of the oestrogenized VP. To evaluate this idea, we analysed nucleolar morphology, and measured the amount of ribosomes and the level of methylation of the 45S ribosomal RNA promoter region. These data indicated that the nucleolus was dismantled and that the methylation at the 45S promoter was increased ( approximately five-fold). Taken together, the results support the idea that the oestrogenized prostate maintains a very low transcriptional level and protein turnover by affecting canonical signalling pathways and promoting nuclear and nucleolar changes.

Role of genetic polymorphism of estrogen receptor-alpha gene and risk of prostate cancer in north Indian population

Present study depicted the role of polymorphisms in estrogen receptor-alpha gene in association with prostate cancer in north Indian population. The study was performed on 157 cases of prostate cancer, 170 cases of BPH, and 170 healthy Indian males diagnosed with prostate cancer and benign prostatic hyperplasia (BPH) and healthy males as controls. Determination of polymorphism in the ER-alpha gene was done by polymerase chain reaction followed by restriction fragment length polymorphism (RFLP) analysis with PvuII and XbaI enzymes. An association was observed between PvuII polymorphism of ER-alpha gene and that of prostate cancer. However, there was no such association with XbaI polymorphism in ER-alpha gene.

Estrogen receptors and function in the male reproductive system

A substantial advance in our understanding on the estrogen signaling occurred in the last decade. Estrogens interact with two receptors, ESR1 and ESR2, also known as ERα and ERβ, respectively. ESR1 and ESR2 belong to the nuclear receptor family of transcription factors. In addition to the well established transcriptional effects, estrogens can mediate rapid signaling, triggered within seconds or minutes. These rapid effects can be mediated by ESRs or the G protein-coupled estrogen receptor GPER, also known as GPR30. The effects of estrogen on cell proliferation, differentiation and apoptosis are often mediated by growth factors. The understanding of the cross-talk between androgen, estrogen and growth factors signaling pathways is therefore essential to understand the physiopathological mechanisms of estrogen action. In this review we focused on recent discoveries about the nature of the estrogen receptors, and on the signaling and function of estrogen in the male reproductive system.

Increased endogenous estrogen synthesis leads to the sequential induction of prostatic inflammation (prostatitis) and prostatic pre-malignancy

Prostatitis causes substantial morbidity to men, through associated urinary symptoms, sexual dysfunction, and pelvic pain; however, 90% to 95% of cases have an unknown etiology. Inflammation is associated with the development of carcinoma, and, therefore, it is imperative to identify and study the causes of prostatitis to improve our understanding of this disease and its role in prostate cancer. As estrogens cause prostatic inflammation, here we characterize the murine prostatic phenotype induced by elevated endogenous estrogens due to aromatase overexpression (AROM+). Early-life development of the AROM+ prostate was normal; however, progressive changes culminated in chronic inflammation and pre-malignancy. The AROM+ prostate was smaller at puberty compared with wild-type controls. Mast cell numbers were significantly increased at puberty and preceded chronic inflammation, which emerged by 40 weeks of age and was characterized by increased mast cell, macrophage, neutrophil, and T-lymphocyte numbers. The expression of key inflammatory mediators was also significantly altered, and premalignant prostatic intraepithelial neoplasia lesions emerged by 52 weeks of age. Taken together, these data link estrogens to prostatitis and premalignancy in the prostate, further implicating a role for estrogen in prostate cancer. These data also establish the AROM+ mouse as a novel, non-bacterial model for the study of prostatitis.

Genetic polymorphisms of estrogen receptors alpha and beta and the risk of developing prostate cancer

Estrogen may be involved in the development of prostate cancer. The association between genetic polymorphisms of estrogen receptors α (ESR1) and β (ESR2) and prostate cancer risk was examined in a nested case-control study in Washington County, Maryland. Incident prostate cancer cases (n = 269) were matched to one or two controls (n = 440) by age, sex, race, and date of blood donation. Associations between estrogen receptor genotypes or dietary intake and the development of prostate cancer were examined in conditional logistic regression models. Results from this study showed that six single base-pair polymorphisms (SNPs) of ESR1 (rs1801132, rs2077647, rs746432, rs2273206, rs851982, rs2228480) and four SNPs of ESR2 (rs4986938, rs928554, rs8018687, rs number not available for ESR2 5696 bp 3′ of STP A>G) were not significantly associated with prostate cancer risk, either by allelic or genotypic frequencies. However, an interactive association with BMI was observed in the relationship between prostate cancer risk and genotypes of ESR2 38 bp 3′ of STP G>A (rs4986938) (p = 0.031). An interaction between intake level of phytoestrogen and genotypes of ESR1 Ex1-192G>C (rs746432) and between intake level of phytoestrogen and genotypes of ESR1 Ex8+229G>A (rs2228480) and risk of prostate cancer was observed (p = 0.0009 and p = 0.044, respectively). In conclusion, selected genetic polymorphisms of ESR1 and ESR2, overall, were not associated with prostate cancer risk. However, a variation in risk by BMI and phytoestrogen intake was implicated.

Neonatal estrogenic effects upon the male rat pituitary: early gonadotrophin attenuation precedes long-term recovery

Neonatal exposure to potent estrogenic compounds can affect multiple components of the male reproductive system causing impaired development of the epithelium and overgrowth of stromal tissue in the epididymis, vas deferens, seminal vesicles, and prostate. However, very little is known about the direct effects of estrogenic compounds on the anterior pituitary gland. In this study we have investigated the effects of neonatal estrogenic exposure upon the anterior pituitary. Both the early- and late-stage effects of exposure to a synthetic estrogenic agent, diethylstilbestrol (DES), upon pituitary gonadotroph cell function were assessed. We administered either a high dose (10 microg) or a low dose (0.1 microg) of DES to male rats during their neonatal period (P2-12). Gonadotroph function, cell number and morphology shortly after DES treatment (P18) and during adulthood (P90) were assessed. At P18 there was a significant decrease in follicle stimulating hormone (FSH) immunoreactivity in the pituitary gonadotroph cells in the high DES dose treated rats compared to control animals. No significant change in luteinizing hormone (LH) was observed at either DES dose. In adulthood (P90), there was no significant difference in FSH or LH gonadotroph immunoreactivity between control rats and any dose of DES-treated rats. Therefore, despite acute and selective ablation of FSH expression the gonadotrophs were able to recover in adulthood, suggesting that perinatal estrogenic exposure was only temporarily deleterious.

Minimum altered regions in early prostate cancer progression identified by high resolution whole genome tiling path BAC array comparative hybridization

BACKGROUND

Carcinoma of the prostate (CaP) is a serious health problem. The altered molecular mechanisms that lead to this disease are poorly understood.

METHODS

Specimens from radical prostatectomies and blood were collected from 18 CaP surgery patients. For CGH studies, 20 CaP-related samples (16 Gleason grade 3, 3 higher grades, 1 BPH sample) and 18 samples of patient-matched normal epithelial cells were obtained by laser-assisted microdissection from frozen sections of the 18 prostatectomy specimens. High resolution SMRT aCGH was used to compare genomic profiles of prostatic samples to patient-matched blood and pooled female DNA. TMPRSS2-ERG fusion transcript analysis was performed by RT-PCR in relation to alterations detected at the TMPRSS2 locus.

RESULTS

Our comprehensive aCGH approach allowed us to define 35 regions of recurrent alterations while excluding germline copy number polymorphisms. Novel regions identified include 2q14.2, containing INHBB, and 17q21.31. The TMPRSS2 locus at 21q22.3 may be a hotspot for rearrangements with 75% of the alterations resulting in the expression of a TMPRSS2-ERG fusion transcript. Differences in fusion expression in different areas in an individual tumor focus and expression in adjacent normal epithelium supported intrafocal heterogeneity and field cancerization, respectively. Both features challenge our efforts to develop more objective markers for diagnosis and prediction of the severity of CaP.

CONCLUSION

The high-density array enabled precise mapping of genomic alterations and consequently definition of minimum altered regions smaller than previously reported thus facilitating identification of those genes that contribute to the cancer transformation process.

Dystroglycan patterns on the prostate of non-obese diabetic mice submitted to glycaemic control

Dystroglycan (DG) is an adhesion protein which plays a crucial role in the maintenance of tissue integrity. Diabetes has been pointed out as a disease which causes harmful effects on prostate function. Therefore, the main objective of this work was to verify DG distribution and structure features in diabetic mice with and without glycaemic control and to relate these parameters to prostate pathogenesis. Thirty mice (Nod and BALB/c) were divided into three groups after 20 days of diabetic state: the control group received a 5 ml/kg dose of physiological saline daily for 20 days; the diabetic group had the same treatment as the control group; the diabetic-insulin group received 4-5 IU doses of Neutral Protamine Hagedorn (NPH) insulin daily for 20 days. After 20 days of treatment, all animals were killed and samples from the ventral prostate were processed for immunological and light microscopy analyses. The results showed diminished beta- and alpha-DG receptors in the diabetic group. However, there was a recovery of both beta-and alpha-DG receptor immunolocalization after insulin administration. Epithelial and stromal morphological changes were verified in the diabetic group, which also presented recovery after insulin treatment. Thus, it could be concluded that diabetes disturbed prostate structure integrity and altered the occurrence of alpha and beta-DG receptors, indicating decreased cell-matrix extracellular and cell-basal membrane attachment. However, insulin treatment could partially restore glandular homeostasis. The decrease in epithelial-stromal interaction certainly predisposes this gland in diabetic mice to be a prostate disease target.

Defects of prostate development and reproductive system in the estrogen receptor-alpha null male mice

The estrogen receptor-alpha knockout (ERalphaKO, ERalpha-/-) mice were generated via the Cre-loxP system by mating floxed ERalpha mice with beta-actin (ACTB)-Cre mice. The impact of ERalpha gene deletion in the male reproductive system was investigated. The ACTB-Cre/ERalpha(-/-) male mice are infertile and have lost 90% of epididymal sperm when compared with wild-type mice. Serum testosterone levels in ACTB-Cre/ERalpha(-/-) male mice are 2-fold elevated. The ACTB-Cre/ERalpha(-/-) testes consist of atrophic and degenerating seminiferous tubules with less cellularity in the disorganized seminiferous epithelia. Furthermore, the ventral and dorsal-lateral prostates of ACTB-Cre/ERalpha(-/-) mice display reduced branching morphogenesis. Loss of ERalpha could also be responsible for the decreased fibroblast proliferation and changes in the stromal content. In addition, we found bone morphogenetic protein, a mesenchymal inhibitor of prostatic branching morphogenesis, is significantly up-regulated in the ACTB-Cre/ERalpha(-/-) prostates. Collectively, these results suggest that ERalpha is required for male fertility, acts through a paracrine mechanism to regulate prostatic branching morphogenesis, and is involved in the proliferation and differentiation of prostatic stromal compartment.

Prostatic squamous metaplasia in a cat with interstitial cell neoplasia in a retained testis

An 11-year-old cat with a retained testis was presented with a chronic history of dysuria and bladder atony. Medical therapy failed to alleviate the clinical signs. Contrast radiography demonstrated a diffusely narrowed urethra. During a celiotomy and prepubic urethrostomy, a retained testis, stenosed urethra, and irregularly enlarged prostate were observed. Histopathologic diagnosis was retained testis with a well-differentiated interstitial cell tumor, a poorly differentiated interstitial cell tumor, and marked squamous metaplasia of the prostatic epithelium with suppurative prostatitis. Neoplastic interstitial cells were immunoreactive for Melan A, consistent with reports of Melan A expression in steroid hormone-producing tissue. This is the first report of prostatic squamous metaplasia associated with testicular neoplasia in a felid.

Inflammation and epithelial alterations in rat prostate: impact of the androgen to oestrogen ratio

Chronic non-bacterial prostatitis may offer new insights into the pathogenesis of human benign prostatic hyperplasia and prostate cancer and the strategies for their treatment and prevention. The potential significance of androgen replacement therapy in terms of the reversal of oestradiol (E(2))-induced inflammatory reaction was studied in the dorsolateral prostate (DLP) of the Noble rat. Castrated Noble rats were treated with E(2) and different doses of androgens [dihydrotestosterone (DHT) and testosterone (T)] to achieve an elevated concentration of E(2) and a wide range of the androgen-to-oestradiol ratios in serum. After the 3-week treatment, inflammatory changes in the DLP were classified and counted. Oestrogen receptor alpha (ER alpha), progesterone receptor (PR), fos-related antigen-2 (Fra2), Ki-67 and P63 were immunocytochemically stained. T, E(2) and prolactin concentrations in serum were measured and the relative weights of the seminal vesicles and pituitary glands and microscopic structures of the DLP and seminal vesicle ducts were determined. Hypoandrogenic doses of DHT (judged on the basis of seminal vesicle weight gain), dose-dependently increased the number of perivascular and stromal inflammatory infiltrates. T and DHT were anti-inflammatory at the doses which normalized or over stimulated the growth of the seminal vesicles. As signs of anti-oestrogenicity, androgens dose-dependently decreased the number and distribution of the ER alpha and PR-positive cells at proinflammatory concentrations. Anti-inflammatory concentrations were needed to reduce the expression of Fra2, E(2)-increased prolactin concentration in serum and pituitary weight. The androgen concentrations required to prevent proinflammatory and epithelial responses to E(2) in the presence of elevated E(2) concentrations may subject the accessory sex glands to more intense androgenic stimulation than is normal for the male. The androgen-resistant endpoints of oestrogen action (body weight reduction and hyperplasia of seminal vesicle ducts) further indicate limitations in the possible preventive effects of androgen-replacement therapy.

Simultaneous haploinsufficiency of Pten and Trp53 tumor suppressor genes accelerates tumorigenesis in a mouse model of prostate cancer

Tumor suppressor gene PTEN is important in the initiation and progression of human prostate carcinoma, whereas the role of TP53 remains controversial. Since Pten/Trp53 double conditional knockout mice show earlier onset and fast progression of prostate cancer when compared to Pten knockout mice, we asked whether heterozygosity of these two tumor suppressor genes was sufficient to accelerate prostatic tumorigenesis. To answer this question we examined prostatic lesion progression of Pten/Trp53 double heterozygous mice and a series of controls such as Pten heterozygous, Pten conditional knockout, Trp53 heterozygous and Trp53 knockout mice. Tissue recombination of adult prostatic epithelium coupled with embryonic rat seminal vesicle mesenchyme was used as a tool to stimulate prostatic epithelial proliferation. In our study, high-grade prostatic intraepithelial neoplasia (PIN) was found with high frequency at 8 weeks post-tissue recombination transplantation. PIN lesions in Pten/Trp53 double heterozygous mice were more severe than those seen in Pten heterozygous alone. Furthermore, morphologic features attributable to Pten or Trp53 loss appeared to be enhanced in double heterozygous tissues. LOH analysis of Pten and Trp53 in genomic DNA collected from high-grade PIN lesions in Pten heterozygous and Pten/Trp53 double heterozygous mice showed an intact wild-type allele for both genes in all samples examined. In conclusion, simultaneous heterozygosity of Pten and Trp53 accelerates prostatic tumorigenesis in this mouse model of prostate cancer independently of loss of heterozygosity of either gene.

Impact of androgen/estrogen ratio: lessons learned from the aromatase over-expression mice

The estrogen signaling plays a pivotal role not only in female reproduction but also in recent years its emerging importance in the males has been shown too. As estrogens and androgens seem to be the two sides of one coin, the better understanding of this physiological and pathophysiological role of androgen/estrogen balance is becoming more crucial. Aromatase is the key enzyme to synthesize estrogens from androgens. Along with the progress of new technologies and tools like transgenic facilities, we are able to analyze in more detail about the involvement of aromatase in the molecular mechanisms underlying the androgen/estrogen essential balance. This review would be dealing with the use of transgenic models over-expressing aromatase in order to analyze the effects of an estrogen/androgen ratio increase in mice, especially on male reproductive biology.

Mesenchymal-epithelial interactions: past, present, and future

This review summarizes the history of research on mesenchymal-epithelial interactions in prostatic development from the first studies in 1970 to the present. From this study we have learned that prostatic development requires a reciprocal interaction between epithelium and mesenchyme in which urogenital sinus mesenchyme induces and patterns epithelial development and differentiation, while developing prostatic epithelium induces and patterns mesenchymal differentiation into smooth muscle and other resident cell types in the stroma. Prostatic development requires androgen action mediated by the androgen receptor (AR). Through analysis of tissue recombinants composed of wild-type and AR-null epithelium and mesenchyme, we have learned that many "androgenic effects" on prostatic epithelium do not require epithelial AR, but instead are elicited by the paracrine action of AR-positive mesenchyme. Present and future studies reviewed in this issue deal with the molecular mechanisms in this developmental communication between epithelium and mesenchyme.

Incidence of prostate cancer in male breast cancer patients: a risk factor for prostate cancer screening

Synchronous or metachronous occurrences of both prostate cancer and male breast cancer are rarely reported, but provide insight into their hormonal and genetic biology. We sought to determine the incidence of prostate cancer in male breast cancer patients at our institution, and to examine estrogen receptor (ER), progesterone receptor (PR) and HER-2/neu receptor (HR) status in these patients. A retrospective review was conducted of male breast cancer patients from 1990 to 2006. Histopathologic characteristics and hormone receptor expression was obtained. In 69 patients with male breast cancer, 12 (17%) also had a diagnosis of prostate cancer. Nine had ER-positive status and three were unreported. PR status was positive in 5, whereas 3 had PR-negative status. HR status was positive in 1, whereas 5 had HR-negative status. Male breast cancer patients in this cohort have an incidence of prostate cancer higher than would be predicted in the general population; this risk factor has implications for careful prostate cancer screening.

The role of estrogens and estrogen receptors in normal prostate growth and disease

Estrogens have significant direct and indirect effects on prostate gland development and homeostasis and have been long suspected in playing a role in the etiology of prostatic diseases. Direct effects are mediated through prostatic estrogen receptors alpha (ERalpha) and beta (ERbeta) with expression levels changing over time and with disease progression. The present review examines the evidence for a role of estrogens and specific estrogen receptors in prostate growth, differentiation and disease states including prostatitis, benign prostatic hyperplasia (BPH) and cancer and discusses potential therapeutic strategies for growth regulation via these pathways.

Prostatic hormonal carcinogenesis is mediated by in situ estrogen production and estrogen receptor alpha signaling

It was recently demonstrated that antiestrogens prevented prostate cancer (PRCA) in men. The source of estradiol (E2) that contributes to carcinogenesis, as well as the selected estrogen receptor (ER) signaling pathway, is unknown. To evaluate estrogen's effects in carcinogenesis, we developed a new model of PRCA utilizing testosterone and E2 to stimulate PRCA. To determine whether local in situ production of E2 affected incidence of PRCA, aromatase-knockout (ArKO) mice were evaluated. In contrast to the wild-type mice, ArKO mice had reduced incidences of PRCA, which implicates in situ production of E2 as an important determinant of PRCA. To determine whether E2-mediated responses were due to ER alpha or ER beta signaling, ER alpha-knockout (alphaERKO) or ERbeta-knockout (betaERKO) mice were used. Prostates from betaERKO mice underwent biochemical and histological carcinogenesis similar to wild-type mice, whereas prostates from alphaERKO mice remained free of pathology. These data suggest that effective prevention of carcinogenesis will require antagonism of ER alpha but not ER beta. This mouse model provides a means to examine genetic gain and loss of function and determine the efficacy of therapeutics on prostatic carcinogenesis.

Oestrogen supplementation following castration promotes stromal remodelling and histopathological alterations in the Mongolian gerbil ventral prostate

The effect of oestradiol on the intact and castrated adult gerbil prostate was evaluated by focussing on stromal and epithelial disorders, and hormonal receptor immunoreactivity. The experimental animals were studied by histological, histochemical and immunohistochemical techniques, morphometric-stereological analysis and transmission electron microscopy. Epithelial alterations in the oestradiol-treated animals were frequent, with an increase in epithelial cell height, areas of intense dysplasia and hyperplasia and formation of prostatic intraepithelial neoplasia (PIN). Another aspect that did not depend on the presence of testosterone was the arrangement of the fibrillar and non-fibrillar elements of the extracellular matrix among smooth muscle cells (SMC), suggesting a possible role of these cells in rearrangement and synthesis of these components, after oestrogenic treatment. In the castrated animals, an accumulation of extracellular matrix elements under the epithelium was evident, while in the intact animals the same compounds were dispersed and scarce. In the groups of intact and castrated animals, SMC and fibroblasts exhibited a secretory phenotype, which was accentuated after oestradiol administration. There was an increase of the immunoreactivity to alpha-oestrogen and androgen receptors in hyperplastic areas compared to normal epithelium, revealing the involvement of these steroid receptors in the hyperplasia and PIN development.

Steroid hormones and carcinogenesis of the prostate: the role of estrogens

Androgens have long been known to be the major sex hormones that target the prostate during development, maturation, and carcinogenesis. It is now apparent that estrogens, both those synthesized by the body as well as those from our environment, also target the prostate during all stages of development. Little is known about the mechanisms involved in estrogen stimulation of carcinogenesis and less is known about how to prevent or treat prostate cancer through estrogenic pathways. To better understand how estrogens mediate their carcinogenic effects, the respective roles of estrogen receptor (ER)-alpha and ER-beta must be elucidated in the epithelial and stromal cells that constitute the prostate. Lastly, the significance of ER signaling during various ontogenic periods must be determined. Answers to these questions will further our understanding of the mechanisms of estrogen/ER signaling and will serve as a basis for chemopreventive and/or chemotherapeutic strategies for prostate cancer.

Bisphenol A induces permanent squamous change in mouse prostatic epithelium

Bisphenol A (BPA) is a monomer of plastic products widely used in daily life, and has weak estrogenic activity. In this study, male BALB/c mice were treated with BPA and diethylstilbestrol (DES) in adult and fetal periods to investigate whether BPA could affect prostatic epithelial differentiation. Eight-to 9-week-old mice treated for 3 weeks with subcutaneous implants of 0.2-200 mg BPA pellets induced the expression of cytokeratin 10 (CK10) in prostatic basal epithelial cells in a dose-dependent manner. Utilizing organ culture of adult prostate, 1 nM and 1 microM BPA also induced CK10 expression and squamous metaplasia with multilayering of basal epithelial cells, respectively. Fetal exposure to low-dose BPA (20 microg/kg/day) from gestation day (GD) 13 to GD18 induced permanent CK10 expression in basal cells of the adult prostate similar to DES (0.2 microg/kg/day). These results indicate that in mouse, BPA can directly elicit CK10 expression in prostatic epithelium, and that this change can be elicited by doses as low as 20 microg/kg/day. We speculate that low-dose BPA during fetal life may also induce permanent squamous change in human prostate.

Treating prostate cancer: a rationale for targeting local oestrogens

Prostate cancer is the most commonly diagnosed cancer and the second most common cause of cancer-related death in men, and benign prostatic hyperplasia is the most common benign condition known to occur in ageing men. Oestrogen has been implicated in the development of prostate cancer, and offers a promising new avenue for treatment. Despite this, the role of oestrogens in the prostate is complex. This Perspective presents a rationale for a targeted approach for the treatment of prostate disease through the use of selective oestrogen-receptor modulators in conjunction with contemporary androgen-ablation therapy.

Delay of postnatal maturation sensitizes the mouse prostate to testosterone-induced pronounced hyperplasia: protective role of estrogen receptor-beta

The role of estrogens in the etiology of prostate cancer is controversial. To demonstrate the specific effects of estrogens and androgens on the development of the prostatic epithelial hyperplasia, we used luteinizing hormone receptor knockout mice (LuRKO), which are resistant to pituitary regulation mediated by luteinizing hormone, lack postnatal androgen production, and have rudimentary accessory sex glands, the growth of which can be induced with exogenous androgen replacement. This model is thus ideal for the investigation of direct hormonal effects on the prostate. Testosterone, but not 5alpha-dihydrotestosterone, replacement from 21 days of life for 8 weeks induced pronounced hyperplasia and inflammation in the prostates of LuRKO mice. Interestingly, 5alpha-dihydrotestosterone combined with 17beta-estradiol did not induce hyperplasia or inflammation, and treatments with inhibitors of estrogen action, aromatase inhibitor, and ICI 182780 further exacerbated testosterone-induced hyperplastic growth. However, the activation of estrogen receptor (ER)-beta with a specific agonist, DPN [2,3-bis(4-hydroxyphenol)-propionitrile], prevented the development of prostatic hyperplasia and inflammation in testosterone-treated LuRKO mice. Thus, it seems that in the presence of sufficient androgenic stimulation, it is the balance between ER-alpha- and ER-beta-mediated signaling that determines whether estrogens promote hyperplasia or protect the prostate against hyperplastic changes.

The prevention of prostate cancer

From our better understanding of the natural history of prostate cancer, it is not unreasonable to believe that the disease is preventable. Prostate cancer has become a major healthcare problem worldwide, as life expectancy increases. Moreover, the cancer is slow growing, with a period of about 20-25 years from initiation to the stage when the clinically detectable phenotype can be identified. This review provides a simple overview of the endocrinology of prostate cancer and discusses some of the pharmaceutical agents that have been or are being tested to restrain, possibly arrest, the progression of this slowly growing cancer. Also discussed are many of the dietary factors that may influence the molecular or endocrine events implicated in its development. Dietary factors are considered responsible for the geographical differences in prostate cancer incidence and mortality. Since about 50% of all men worldwide, from both East and West, show evidence of microscopic cancer by 50 years of age, growth restraint would appear to be the pragmatic option to the possibility of preventing initiation.

The role of Eralpha and ERbeta in the prostate: insights from genetic models and isoform-selective ligands

Androgens are known regulators of the growth and differentiation of the prostate gland and are effective during development and maturity as well as in disease. The role of estrogens is less well characterized, but dual direct and indirect actions on prostate growth and differentiation have been demonstrated, facilitated via both ERalpha, and ERbeta. Previous studies using animal models to determine the role of ERbeta in the prostate have been problematic due to the centrally mediated responses to estrogen administration via ERalpha that can lower androgen levels and lead to epithelial regression, thereby masking any direct effects on the prostate mediated by ERbeta. Our alternate approach was to use the estrogen-deficient aromatase knockout (ArKO) mouse and the method of tissue recombination to provide new insight into estrogen action on prostate growth and pathology. Firstly, utilizing homo- and heterotypic tissue recombinants, we demonstrate that stromal aromatase deficiency results in the induction of hyperplasia in previously normal prostatic epithelium and that this response is the result of local changes to the paracrine interaction between stroma and epithelium. Secondly, using tissue recombination and an ERbeta-specific agonist, we demonstrate that the activation of ERbeta results in an anti-proliferative response that is not influenced by alterations to systemic androgen levels or activation of ERalpha. Finally, using intact ArKO mice this study demonstrates that the administration of an ERbeta-specific agonist abrogates existing hyperplastic epithelial pathology specifically in the prostate but an ERbeta-specific agonist does not. Therefore, in the absence of stromal aromatase gene expression, epithelial proliferation, leading to prostatic hypertrophy and hyperplasia, may result from a combination of androgenic stimulation of proliferation and failed activation of ERbeta by locally synthesized estrogens. These data demonstrate essential and beneficial effects of estrogens that are necessary for normal growth of the prostate and distinguish them from those that adversely alter prostate growth and differentiation. This indicates the potential of antiandrogens and SERMS, as opposed to aromatase inhibitors, for the management of prostate hyperplasia and hypertrophy.

Transcript profiling of the androgen signal in normal prostate, benign prostatic hyperplasia, and prostate cancer

Human prostate adenocarcinoma (CaP) and benign prostatic hyperplasia (BPH) have epithelial and stromal cell origins, respectively. To determine whether the androgen signal is processed differently in these cell types the expression of transcripts for enzymes that control ligand access to the androgen receptor (AR) were measured. Transcripts for type 2 5alpha-reductase, ketosteroid reductases [aldo-keto reductase (AKR)1C1-AKR1C4], the major oxidative 3alpha-hydroxysteroid dehydrogenase (HSD) retinol dehydrogenase (RODH)-like 3alpha-HSD (RL-HSD) and nuclear receptors [AR, estrogen receptor (ER)alpha, and ERbeta] were determined in whole human prostate and in cultures of primary epithelial cells (PEC) and primary stromal cells (PSC) from normal prostate, CaP and BPH by real-time RT-PCR. Normal PEC (n=14) had higher levels of AKR1C1 (10-fold, P<0.001), AKR1C2 (115-fold, P<0.001) and AKR1C3 (6-fold, P<0.001) than normal PSC (n=15), suggesting that reductive androgen metabolism occurs. By contrast, normal PSC had higher levels of AR (8-fold, P<0.001) and RL-HSD (21-fold, P<0.001) than normal PEC, suggesting that 3alpha-androstanediol is converted to 5alpha-dihydrotestosterone to activate AR. In CaP PEC (n=14), no significant changes in transcript levels vs. normal PEC were observed. In BPH PSC (n=21) transcripts for AR (2-fold, P<0.001), AKR1C1 (4-fold, P<0.001), AKR1C2 (10-fold P<0.001), AKR1C3 (4-fold, P<0.001) and RL-HSD (3-fold, P<0.003) were elevated to increase androgen response. Differences in the AR:ERbeta transcript ratios (eight in normal PEC vs. 280 in normal PSC) were maintained in PEC and PSC in diseased prostate. These data suggest that CaP may be more responsive to an ERbeta agonist and BPH may be more responsive to androgen ablation.

Morphometric and morphological features of the ventral prostate in rats submitted to chronic nicotine and alcohol treatment

Clinical studies analyzing simultaneous nicotine-alcohol use by patients showed important alterations in various organic systems such as: respiratory, digestory, and genital. Also, the prostatic morphology and physiology have been analyzed, specially due to large occurrence of prostatic diseases. Then, this work aimed at determining the structure and ultrastructure of the prostatic stroma and epithelium, as well as the stroma epithelium interactions from rats submitted to simultaneous long-term alcohol-nicotine treatment. A total of 40 male rats were divided into four groups: control group (10 animals) received tap water; alcoholic group (10 animals) received diluted 10% Gay Lussac ethanol; nicotine group (10 animals) received a 0.125mg/100g of body weight dose of nicotine injected subcutaneosly on a daily basis; nicotine-alcohol group (10 animals) received simultaneous alcohol and nicotine treatment. After 90 days of treatment, the animals were sacrificed and samples from the ventral lobe of the prostate were collected and processed for transmission electron and light microscopies. The results showed atrophied epithelium; prostatic intra-epithelial neoplasia; dilated cisterns of the granular endoplasmic reticulum, large amounts of collagen fibers besides inflammatory cells, specially in the alcoholic and nicotine-alcohol groups. Therefore, it could be concluded that the association between alcohol and nicotine caused the impairment of the prostatic secretory process. Moreover, this association is related to prostatic pathogenesis, which could lead to late glandular malignancy.

A novel polymorphism in the 17β-hydroxysteroid dehydrogenase type 5 (aldo-keto reductase 1C3) gene is associated with lower serum testosterone levels in caucasian men

Genetic variation in the androgen metabolizing enzymes is important to identify and feature as they may influence the risk of prostate cancer and help clarify the etiology of the disease. Human 17beta-hydroxysteroid dehydrogenase type 5 (AKR1C3) is highly expressed in the prostate gland and plays a major role in the formation and metabolism of androgens. We identified five novel polymorphisms in the AKR1C3 gene. One of those an A>G substitution in exon 2 that confers a Glu77Gly change occurred in 4.8% in Caucasians but was completely absent in Orientals. Interestingly, the testosterone level in serum was significantly lower in subjects with the Gly77 allele. A promoter A>G polymorphism was associated with significantly altered promoter activity in reporter constructs, but was not associated with any change in testosterone levels. In conclusion, the Glu77Gly polymorphism is associated with lower testosterone levels in serum.

Isolation and characterization of an immortalized mouse urogenital sinus mesenchyme cell line

BACKGROUND

Stromal-epithelial signaling plays an important role in prostate development and cancer progression. Study of these interactions will be facilitated by the use of suitable prostate cell lines in appropriate model systems.

METHODS

We have isolated an immortalized prostate mesenchymal cell line from the mouse E16 urogenital sinus (UGS). We characterized its expression of stromal differentiation markers, response to androgen stimulation, ability to induce and participate in prostate morphogenesis, response to Shh stimulation, and interaction with prostate epithelial cells.

RESULTS

UGSM-2 cells express vimentin and smooth muscle actin, but not the mature smooth muscle markers myosin and desmin. This expression profile is consistent with a myofibroblast phenotype. Unlike other fibroblasts such as 3T3, UGSM-2 cells express androgen receptor mRNA and androgen stimulation increases proliferation. UGSM-2 cells are viable when grafted with embryonic UGS under the renal capsule and participate in glandular morphogenesis, but are not capable of inducing prostate morphogenesis of isolated UGS epithelium. Co-culture of UGSM-2 cells with human BPH-1 cells or co-grafting in vivo results in organized clusters of BPH-1 cells surrounded by a mantle of UGSM-2 cells. UGSM-2 cells are responsive to Sonic hedgehog (Shh), an important signaling factor in prostate development, and mimic the transcriptional response of the intact UGS mesenchyme. In co-cultures with BPH-1, UGSM-2 cells exhibit a robust transcriptional response to Shh secreted by BPH-1.

CONCLUSIONS

UGSM-2 is a urogenital sinus mesenchyme cell line that can be used to study stromal-epithelial interactions that are important in prostate biology.

Steroid hormones stimulate human prostate cancer progression and metastasis

Tissue recombinants (TRs) composed of mouse urogenital mesenchyme (mUGM) plus an immortalized nontumorigenic human prostatic epithelial cell line (BPH-1) were grown under the kidney capsule of male athymic nude mice under different hormonal conditions. The objectives were to determine temporal plasma concentrations of testosterone (T) and estradiol-17beta (E2) that elicit progression of nontumorigenic human prostatic epithelial cells in vivo. Second, to determine whether mUGM+BPH-1 TRs in [T+E2]-treated hosts could progress to metastases. Control mouse hosts received no exogenous hormonal support, whereas treated mice received Silastic implants containing T and E2 for 1-4 months. Plasma from hormonally treated mice contained significantly higher (p < 0.01) concentrations of T at 1 month (11.7 vs. 0.9 ng/ml). Plasma levels of E2 in steroid implanted mice were significantly higher (p < 0.05) at 2 months (104.5 vs. 25.6 ng/l) and 4 months (122.8 vs. 19.2 pg/ml). Wet weights of mUGM+BPH-1 TRs from [T+E2]-implanted mice were significantly larger (p < 0.001) than those from untreated hosts. Untreated mUGM+BPH-1 TRs contained a well organized differentiated epithelium surrounded by smooth muscle stroma similar to developing prostate. In [T+E2]-implanted mice, mUGM+BPH-1 TRs formed carcinomas that contained a fibrous connective tissue stroma permeating the tumor; smooth muscle when present was associated with vasculature. Renal lymph nodes collected from [T+E2]-treated mice, but not untreated mice, contained metastatic carcinoma cells. Moreover, metastases could be observed at distant sites including lung and liver. Epithelial cells isolated from untreated mUGM+BPH-1 TRs exhibited benign histology and formed small nontumorigenic grafts when subsequently transplanted into athymic nude mice. In contrast, epithelial cells isolated from mUGM+BPH-1 tumors of [T+E2]-treated hosts formed large tumors that grew independent of stromal and hormonal support and developed lymph node metastases. We conclude that [T+E2]-treatment promotes prostatic cancer progression in mUGM+BPH-1 TRs. Use of mUGM in this system will allow future studies to utilize the power of mouse genetics to identify paracrine factors involved in human prostatic carcinogenesis.

Estrogen receptors and human disease

Estrogens influence many physiological processes in mammals, including but not limited to reproduction, cardiovascular health, bone integrity, cognition, and behavior. Given this widespread role for estrogen in human physiology, it is not surprising that estrogen is also implicated in the development or progression of numerous diseases, which include but are not limited to various types of cancer (breast, ovarian, colorectal, prostate, endometrial), osteoporosis, neurodegenerative diseases, cardiovascular disease, insulin resistance, lupus erythematosus, endometriosis, and obesity. In many of these diseases, estrogen mediates its effects through the estrogen receptor (ER), which serves as the basis for many therapeutic interventions. This Review will describe diseases in which estrogen, through the ER, plays a role in the development or severity of disease.