Developmental estrogenization and prostatic neoplasia

The Translational Role of Animal Models for Estrogen-Related Functional Bladder Outlet Obstruction and Prostatic Inflammation

The prevalence of LUTS and prostatic diseases increases with age both in humans and companion animals, suggesting that a common underlying cause of these conditions may be age-associated alterations in the balance of sex hormones. The symptoms are present with different and variable micturition dysfunctions and can be assigned to different clinical conditions including bladder outlet obstruction (BOO). LUTS may also be linked to chronic non-bacterial prostatitis/chronic pelvic pain syndrome (CP/CPPS), but the relationship between these conditions is unknown. This review summarizes the preclinical data that supports a role for excessive estrogen action in the development of obstructive voiding and nonbacterial prostatic inflammation. Preclinical studies that are emphasized in this review have unequivocally indicated that estrogens can induce functional and structural changes resembling those seen in human diseases. Recognizing excessive estrogen action as a possible hormonal basis for the effects observed at multiple sites in the LUT may inspire the development of innovative treatment options for human and animal patients with LUTS associated with functional BOO and CP/CPPS.

Ontogeny of estrogen receptors in human male and female fetal reproductive tracts

This paper reviews and provides new observations on the ontogeny of estrogen receptor alpha (ESR1) and estrogen receptor beta (ESR2) in developing human male and female internal and external genitalia. Included in this study are observations on the human fetal uterine tube, the uterotubal junction, uterus, cervix, vagina, penis and clitoris. We also summarize and report on the ontogeny of estrogen receptors in the human fetal prostate, prostatic urethra and epididymis. The ontogeny of ESR1 and ESR2, which spans from 8 to 21 weeks correlates well with the known "window of susceptibility" (7-15 weeks) for diethylstilbestrol (DES)-induced malformations of the human female reproductive tract as determined through examination of DES daughters exposed in utero to this potent estrogen. Our fairly complete mapping of the ontogeny of ESR1 and ESR2 in developing human male and female internal and external genitalia provides a mechanistic framework for further investigation of the role of estrogen in normal development and of abnormalities elicited by exogenous estrogens.

Postnatal exposure to finasteride causes different effects on the prostate of male and female gerbils

The development and maintenance of prostate function depend on a fine balance between oestrogen and androgen levels. Finasteride inhibits 5α-reductase, which is responsible for the conversion of testosterone into its most active form, dihydrotestosterone. Enzymes that metabolize these hormones have a highly relevant role in both the normal prostate metabolism and in the occurrence of pathological conditions. There are few studies on the impact of finasteride on male prostate development and fewer studies on the female prostate and possible intersexual differences. Therefore, we treated male and female gerbils from 7 to 14 days in postnatal life with a high dose of finasteride (500 μg/kg/day); the prostate complexes were then removed and submitted to immunohistochemistry, immunofluorescence and three-dimensional reconstruction. In addition, hormonal serum dosages were administered. Treatment with finasteride resulted in an increased thickness of the periductal smooth musculature in the prostate of both male and female gerbils, such as well as a reduction in the thickness of developing prostate alveoli in both sexes. In addition, intersexual differences were observed as increased epithelial proliferation and decreases in the number of developing alveoli in females. Together, the data indicate that postnatal exposure to finasteride causes greater changes in the female gerbil prostate than in the male.

The resurgence of estrogens in the treatment of castration-resistant prostate cancer

Use of exogenous estrogens in manipulating the androgenestrogen equilibrium was one of the earliest therapeutic strategies developed to treat prostate cancer which followed close on heels the discovery of hormone dependence of this tumor. Despite its well-documented benefit, estrogen therapy fell out of favor with the advent of other forms of androgen deprivation therapy (ADT) as the former registered a higher incidence of cardiovascular complications and poorer overall survival. Clearer understanding of the mechanism of action of estrogen coupled with the adoption of alternative routes of administration has triggered a renewed interest in estrogen therapy. Since then, many studies have not only proved the therapeutic benefit of estrogens but also explored the ways and means of minimizing the dreaded side effects deterring its use. Further, the fact that estrogen therapy offered a clear advantage of reduced cost of treatment over other treatments has led many countries to readopt it in the treatment of advanced prostatic cancer. We reviewed the published data on the use of estrogens in CRPC, which may affect its revival as an efficacious treatment option having minimal side effects, with modified dosage and route of administration. Estrogen therapy would be a less expensive option having equivalent or even better therapeutic effect than ADT in advanced carcinoma of prostate.

[Study of anogenital distance as a diagnostic tool for prostate cancer]

INTRODUCTION AND OBJECTIVE

The distance from the genitals to the anus (anogenital distance [AGD]) reflects androgen concentration during prenatal development in mammals. At the present time, there is only one study suggesting the relationship between AGD and risk of prostate cancer (CaP). The goal of this study was to assess the performance and clinical utility of AGD, as a biomarker of prenatal androgenic milieu, and risk of CaP in a larger population, in CaP diagnosis.

MATERIAL AND METHODS

A case-control study was conducted on 260 men seen in a hospital outpatient clinic where underwent a physical and andrological examination and completed a brief questionnaire. CaP patients were confirmed by biopsy of the tumor. Controls were men without CaP seen in the urology outpatient clinic for routine examinations. Two variants of AGD (from the anus to the posterior base of the scrotum [AGD_AS] and to the cephalad insertion of the penis [AGD_AP]) were measured. Parametric and non-parametric tests and receiver operating characteristic (COR) analyses were used to determine relationships between AGD and presence of CaP.

RESULTS

The highest area under the curve (0.69; 95% CI 0.60 to 0.78 and 0.69; 95% CI 0.61 to 0.77) was obtained for the Gleason=7 subgroup with the AGD_AS and AGD_AP measurement, with a sensitivity and specificity of 83% and 55%, and 91% and 41%, the predictive positive value of 39% and 35% and negative value of 90% and 93% respectively.

CONCLUSION

AGD may be a useful clinical tool for the CaP diagnosis.

Environmental endocrine disruptors: Effects on the human male reproductive system

Incidences of altered development and neoplasia of male reproductive organs have increased during the last 50 years, as shown by epidemiological data. These data are associated with the increased presence of environmental chemicals, specifically "endocrine disruptors," that interfere with normal hormonal action. Much research has gone into testing the effects of specific endocrine disrupting chemicals (EDCs) on the development of male reproductive organs and endocrine-related cancers in both in vitro and in vivo models. Efforts have been made to bridge the accruing laboratory findings with the epidemiological data to draw conclusions regarding the relationship between EDCs, altered development and carcinogenesis. The ability of EDCs to predispose target fetal and adult tissues to neoplastic transformation is best explained under the framework of the tissue organization field theory of carcinogenesis (TOFT), which posits that carcinogenesis is development gone awry. Here, we focus on the available evidence, from both empirical and epidemiological studies, regarding the effects of EDCs on male reproductive development and carcinogenesis of endocrine target tissues. We also critique current research methodology utilized in the investigation of EDCs effects and outline what could possibly be done to address these obstacles moving forward.

MicroRNA-135b regulates ERα, AR and HIF1AN and affects breast and prostate cancer cell growth

MicroRNAs (miRNAs) regulate a wide range of cellular signaling pathways and biological processes in both physiological and pathological states such as cancer. We have previously identified miR-135b as a direct regulator of androgen receptor (AR) protein level in prostate cancer (PCa). We wanted to further explore the relationship of miR-135b to hormonal receptors, particularly estrogen receptor α (ERα). Here we show that miR-135b expression is lower in ERα-positive breast tumors as compared to ERα-negative samples in two independent breast cancer (BCa) patient cohorts (101 and 1302 samples). Additionally, the miR-135b expression is higher in AR-low PCa patient samples (47 samples). We identify ERα as a novel miR-135b target by demonstrating miR-135b binding to the 3'UTR of the ERα and decreased ERα protein and mRNA level upon miR-135b overexpression in BCa cells. MiR-135b reduces proliferation of ERα-positive BCa cells MCF-7 and BT-474 as well as AR-positive PCa cells LNCaP and 22Rv1 when grown in 2D. To identify other genes regulated by miR-135b we performed gene expression studies and found a link to the hypoxia inducible factor 1α (HIF1α) pathway. We show that miR-135b influences the protein level of the inhibitor for hypoxia inducible factor 1α (HIF1AN) and is able to bind to HIF1AN 3'UTR. Our study demonstrates that miR-135b regulates ERα, AR and HIF1AN protein levels through interaction with their 3'UTR regions, and proliferation in ERα-positive BCa and AR-positive PCa cells.

Fetal alcohol exposure increases susceptibility to carcinogenesis and promotes tumor progression in prostate gland

The idea that exposure to adverse environmental conditions and lifestyle choices during pregnancy can result in fetal programming that underlies disease susceptibility in adulthood is now widely accepted. Fetal alcohol exposed offspring displays many behavioral and physiological abnormalities including neuroendocrine-immune functions, which often carry over into their adult life. Since the neuroendocrine-immune system plays an important role in controlling tumor surveillance, fetal alcohol exposed offspring can be vulnerable to develop cancer. Animal studies have recently showed increased cancer growth and progression in various tissues of fetal alcohol exposed offspring. I will detail in this chapter the recent evidence for increased prostate carcinogenesis in fetal alcohol exposed rats. I will also provide evidence for a role of excessive estrogenization during prostatic development in the increased incidence of prostatic carcinoma in these animals. Furthermore, I will discuss the additional possibility of the involvement of impaired stress regulation and resulting immune incompetence in the increased prostatic neoplasia in the fetal alcohol exposed offspring.

Bisphenol A promotes human prostate stem-progenitor cell self-renewal and increases in vivo carcinogenesis in human prostate epithelium

Previous studies in rodent models have shown that early-life exposure to bisphenol A (BPA) reprograms the prostate and enhances its susceptibility to hormonal carcinogenesis with aging. To determine whether the human prostate is similarly sensitive to BPA, the current study used human prostate epithelial stem-like cells cultured from prostates of young, disease-free donors. Similar to estradiol-17β (E2), BPA increased stem-progenitor cell self-renewal and expression of stem-related genes in a dose-dependent manner. Further, 10 nM BPA and E2 possessed equimolar membrane-initiated signaling with robust induction of p-Akt and p-Erk at 15 minutes. To assess in vivo carcinogenicity, human prostate stem-progenitor cells combined with rat mesenchyme were grown as renal grafts in nude mice, forming normal human prostate epithelium at 1 month. Developmental BPA exposure was achieved through oral administration of 100 or 250 μg BPA/kg body weight to hosts for 2 weeks after grafting, producing free BPA levels of 0.39 and 1.35 ng/mL serum, respectively. Carcinogenesis was driven by testosterone plus E2 treatment for 2 to 4 months to model rising E2 levels in aging men. The incidence of high-grade prostate intraepithelial neoplasia and adenocarcinoma markedly increased from 13% in oil-fed controls to 33% to 36% in grafts exposed in vivo to BPA (P < .05). Continuous developmental BPA exposure through in vitro (200 nM) plus in vivo (250 μg/kg body weight) treatments increased high-grade prostate intraepithelial neoplasia/cancer incidence to 45% (P < .01). Together, the present findings demonstrate that human prostate stem-progenitor cells are direct BPA targets and that developmental exposure to BPA at low doses increases hormone-dependent cancer risk in the human prostate epithelium.

Oxidative stress in prostate cancer: changing research concepts towards a novel paradigm for prevention and therapeutics

A mounting body of evidence suggests that increased production of reactive oxygen species (ROS) is linked to aging processes and to the etiopathogenesis of aging-related diseases, such as cancer, diabetes, atherosclerosis and degenerative diseases like Parkinson's and Alzheimer's. Excess ROS are deleterious to normal cells, while in cancer cells, they can lead to accelerated tumorigenesis. In prostate cancer (PC), oxidative stress, an innate key event characterized by supraphysiological ROS concentrations, has been identified as one of the hallmarks of the aggressive disease phenotype. Specifically, oxidative stress is associated with PC development, progression and the response to therapy. Nevertheless, a thorough understanding of the relationships between oxidative stress, redox homeostasis and the activation of proliferation and survival pathways in healthy and malignant prostate remains elusive. Moreover, the failure of chemoprevention strategies targeting oxidative stress reduced the level of interest in the field after the recent negative results of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) trial. Therefore, a revisit of the concept is warranted and several key issues need to be addressed: The consequences of changes in ROS levels with respect to altered redox homeostasis and redox-regulated processes in PC need to be established. Similarly, the key molecular events that cause changes in the generation of ROS in PC and the role for therapeutic strategies aimed at ameliorating oxidative stress need to be identified. Moreover, the issues whether genetic/epigenetic susceptibility for oxidative stress-induced prostatic carcinogenesis is an individual phenomenon and what measurements adequately quantify prostatic oxidative stress are also crucial. Addressing these matters will provide a more rational basis to improve the design of redox-related clinical trials in PC. This review summarizes accepted concepts and principles in redox research, and explores their implications and limitations in PC.

Bisphenol A exposure during adulthood alters expression of aromatase and 5α-reductase isozymes in rat prostate

The high incidence of prostate cancer (PCa) and benign prostatic hypertrophy (BPH) in elderly men is a cause of increasing public health concern. In recent years, various environmental endocrine disruptors, such as bisphenol A (BPA), have been shown to disrupt sexual organs, including the prostate gland. However, the mechanisms underlying these effects remain unclear. Because androgens and estrogens are important factors in prostate physiopathology, our objective was to examine in rat ventral prostate the effects of adult exposure to BPA on 5α-Reductase isozymes (5α-R types 1, 2, and 3) and aromatase, key enzymes in the biosynthesis of dihydrotestosterone and estradiol, respectively. Adult rats were subcutaneously injected for four days with BPA (25, 50, 300, or 600 µg/Kg/d) dissolved in vehicle. Quantitative RT-PCR, western blot and immunohistochemical analyses showed lower mRNA and protein levels of 5α-R1 and 5α-R2 in BPA-treated groups versus controls but higher mRNA levels of 5α-R3, recently proposed as a biomarker of malignancy. However, BPA treatment augmented mRNA and protein levels of aromatase, whose increase has been described in prostate diseases. BPA-treated rats also evidenced a higher plasma estradiol/testosterone ratio, which is associated with prostate disease. Our results may offer new insights into the role of BPA in the development of prostate disease and may be of great value for studying the prostate disease risk associated with exposure to BPA in adulthood.

The impact of cow's milk-mediated mTORC1-signaling in the initiation and progression of prostate cancer

Prostate cancer (PCa) is dependent on androgen receptor signaling and aberrations of the PI3K-Akt-mTORC1 pathway mediating excessive and sustained growth signaling. The nutrient-sensitive kinase mTORC1 is upregulated in nearly 100% of advanced human PCas. Oncogenic mTORC1 signaling activates key subsets of mRNAs that cooperate in distinct steps of PCa initiation and progression. Epidemiological evidence points to increased dairy protein consumption as a major dietary risk factor for the development of PCa. mTORC1 is a master regulator of protein synthesis, lipid synthesis and autophagy pathways that couple nutrient sensing to cell growth and cancer. This review provides evidence that PCa initiation and progression are promoted by cow´s milk, but not human milk, stimulation of mTORC1 signaling. Mammalian milk is presented as an endocrine signaling system, which activates mTORC1, promotes cell growth and proliferation and suppresses autophagy. Naturally, milk-mediated mTORC1 signaling is restricted only to the postnatal growth phase of mammals. However, persistent consumption of cow´s milk proteins in humans provide highly insulinotropic branched-chain amino acids (BCAAs) provided by milk´s fast hydrolysable whey proteins, which elevate postprandial plasma insulin levels, and increase hepatic IGF-1 plasma concentrations by casein-derived amino acids. BCAAs, insulin and IGF-1 are pivotal activating signals of mTORC1. Increased cow´s milk protein-mediated mTORC1 signaling along with constant exposure to commercial cow´s milk estrogens derived from pregnant cows may explain the observed association between high dairy consumption and increased risk of PCa in Westernized societies. As well-balanced mTORC1-signaling plays an important role in appropriate prostate morphogenesis and differentiation, exaggerated mTORC1-signaling by high cow´s milk consumption predominantly during critical growth phases of prostate development and differentiation may exert long-term adverse effects on prostate health. Attenuation of mTORC1 signaling by contemporary Paleolithic diets and restriction of dairy protein intake, especially during mTORC1-dependent phases of prostate development and differentiation, may offer protection from the most common dairy-promoted cancer in men of Western societies.

Harmful effects of carbamazepine on the postnatal development of the rat ventral prostate

BACKGROUND

Carbamazepine (CBZ) is a first-line antiepileptic drug (AED), although it is also used for the treatments of psychiatric disorders and neuropathic pain. The CBZ utilization has been associated with male reproductive damage, including hormonal alterations, sexual dysfunction and reduction of sperm quality. The wide and long-term use of the CBZ is a common schedule in children and adolescents and alters the testosterone level in adult rats and humans. The objective of this work was to evaluate the CBZ side effects on the ventral prostate of rats from pre-puberty to sexual maturation, since the prostate is an androgen-dependent organ.

METHODS

Twenty three day-old male albino Wistar rats received CBZ diluted in propylene glycol (20 mg/Kg/i.p via). The treatment lasted 20, 40 and 70 days, according to the different stages of the rat sexual maturation. At the end of each treatment period, ventral prostates were removed and histologically processed. The prostate sections were submitted to the histopathological, morphological and stereological analyses using image analysis system.

RESULTS

Reductions of the glandular epithelium, glandular lumen and fibromuscular stroma volume of the ventral prostate were observed in adult rats treated with CBZ since the weaning. Triggering and degranulation of mast cells were observed in the fibromuscular stroma of prepubertal and pubertal CBZ treated rats.

CONCLUSIONS

The results suggest a direct effect of the CBZ on rat ventral prostate, evidenced by increase of mast cell and macrophage populations during pre-puberty and puberty causing a ventral prostate accentuated damage in the adult phase.

Estrogen receptor beta expression in prostate adenocarcinoma

Background

Prostate cancer is the most commonly diagnosed cancer in men and the second leading cause of cancer death in men. Estrogen induction of cell proliferation is a crucial step in carcinogenesis of gynecologic target tissues, and there are many studies recently done, showing that prostate cancer growth is also influenced by estrogen. The characterization of estrogen receptor beta (ER-b) brought new insight into the mechanisms underlying estrogen signalling. In the present study, we investigated the expression of estrogen receptor-b (ER-b) in human prostate cancer tissues.

Methods

We selected 52 paraffin-embedded blocks of prostate needle biopsies in a cross-sectional study to determine frequency and rate of ER-b expression in different grades of prostate adenocarcinoma according to Gleason grading system. Immunohistochemical staining of tissue sections by monoclonal anti ER-b antibody was performed using an Envision method visualising system.

Results

ER-b expression was seen in tumoral cells of prostatic carcinoma in all 29 cases with low and intermediate tumors (100%) and 19 of 23 cases with high grade tumor (83%). Mean rate of ER-b expression in low & intermediate grade cancers was 68.41% (SD = 25.63) whereas high grade cancers showed 49.48% rate of expression (SD = 28.79).

Conclusions

ER-b expression is reduced in high grade prostate cancers compared to low & intermediate grade ones (P value 0.027).

Exposure to ethinylestradiol during prenatal development and postnatal supplementation with testosterone causes morphophysiological alterations in the prostate of male and female adult gerbils

Steroids perform significant functions in prostatic development and growth, so that interferences of this equilibrium may predispose the gland to the development of diseases during the life. Embryonic and neonatal exposure to xenoestrogens, many of them with endocrine-disrupting potential, has been related to the induction of disturbances in reproductive system organs. Thus, this study aimed to analyse morphological and immunocytochemical aspects of prostate in both male and female adult gerbils either exposed to ethinylestradiol during the prenatal phase (pregnant females received 10 μg/kg, by gavage) (EE group) or exposed to testosterone (1 mg/kg) during the postnatal period (EE/T group). Serological analysis revealed a rise in estradiol levels in adult males and females of the EE group. A higher incidence of prostatic intraepithelial neoplasia (PIN) was observed in the male and female prostate of the treated groups, besides an increase in collagen and reticular fibres. Immunocytochemistry showed an increase in prostatic epithelial cells immunoreactive to AR and a presence of a smooth muscle layer, evidenced by α actin, in injured regions this way absent in prostatic epithelial buds. These pieces of evidence suggest that the alterations verified in the prostate in adulthood of both sexes may be due to the high oestrogen levels. Either males or females of the EE/T group showed normalized estradiol levels, although prostatic lesions could be observed. While the prostatic gland of male gerbils was more affected than the female prostate, this study showed that the exposure to EE during this critical period of development disrupts the prostate of both sexes in terms of prostatic lesions.

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.

Novel biomarkers for risk of prostate cancer: results from a case-control study

BACKGROUND

Although the estrogens estrone and estradiol are recognized to play very important roles in the risk of developing prostate cancer (Pca), the molecular mechanism by which estrogens initiate and/or promote Pca is still unknown. Substantial evidence supports that specific metabolites of estrogens, catechol estrogen quinones, can react with DNA to form depurinating estrogen-DNA adducts. Apurinic sites derived from depurination of these adducts can induce mutations leading to cancer. Once released from DNA, depurinating estrogen-DNA adducts are shed from cells into the bloodstream and excreted in urine. By analyzing profiles of estrogen metabolites, conjugates, and depurinating DNA adducts in urine from men with and without prostate cancer, potential biomarkers of Pca can be detected. The goal of this case-control study was to detect and identify potential biomarkers of Pca.

METHODS

Urine samples from fourteen cases, men diagnosed with Pca, and 125 controls, men who had not been diagnosed with Pca, were partially purified by solid phase extraction and analyzed by ultraperformance liquid chromatography/tandem mass spectrometry. The urinary levels of androgens, estrogens, estrogen metabolites, conjugates and depurinating DNA adducts were measured.

RESULTS

The ratio of depurinating estrogen-DNA adducts to the sum of the corresponding estrogen metabolites and conjugates was significantly higher in cases (median: 57.34) compared to controls (median: 23.39) (P < 0.001).

CONCLUSIONS

This study suggests that depurinating estrogen-DNA adducts could serve as potential biomarkers to predict risk of Pca. They also could be useful tools for early clinical diagnosis and development of suitable strategies to prevent Pca.

Association between estrogen and androgen receptor genes and prostate cancer risk

OBJECTIVE

Prostate cancer (PC) is one of the principal causes of death among men. Steroid hormones are involved in normal prostate growth and carcinogenesis. The purpose of our study was to investigate the effects on PC risk of polymorphisms from three steroid hormone receptor genes: the androgen (AR), and the alpha (ESR1) and beta (ESR2) estrogen receptors.

DESIGN AND METHODS

The study was performed on a Caucasian population of 1045 PC patients and 814 controls. Using a logistic regression model, the different alleles and genotypes from those polymorphisms were analyzed according to case/control status, the tumor aggressiveness, and the age at onset.

RESULTS

A significant association between PC risk and the pooled 4/5, 5/6, and 6/6 genotypes of the GGGA repeat located in the first intron of ESR1 (odds ratio (OR)=3.00, 95% CI=1.32-6.82, P=0.008) was observed. When we stratified the cases, this association was confined to patients with a Gleason score of 2-4 (OR=8.34, 95% CI=2.91-23.91, P<0.0001) or late onset PC (OR=2.91, 95% CI=1.22-6.93, P=0.016). An association between a short AR CAG repeat (less than 17 repeats) was also observed among patients with late onset PC (OR=2.34, 95% CI=1.15-4.76, P=0.019).

CONCLUSIONS

These findings suggest that the GGGA repeat from ESR1 and the CAG repeat from AR may be associated with risk of late onset PC.

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.

Estrogen-regulated development and differentiation of the prostate

Both androgens and estrogens play a significant role in the prostate and are critical for normal prostate growth and development, as well as the maintenance of adult prostatic homeostasis throughout life. It is the balance of these two hormones, rather than each individually, that is important for prostatic development and differentiation. Estrogen action is mediated by the estrogen receptors, ERalpha and ERbeta. ERalpha is expressed throughout the prostatic tissue during fetal and early neonatal life, and if activated inappropriately, produces late-life disease, including inflammation and emergence of pre-malignant pathologies. In contrast, ERbeta expression is initiated after ERalpha, is localized primarily to the epithelium, and appears to be important during later periods of development such as puberty and adulthood, acting to regulate cellular proliferation and differentiation in the adult tissue. Therefore, there is also a spatial and temporal balance between ERalpha and ERbeta that is critical for development. Together with the shifting balance between androgens and estrogens themselves, the subtle, yet critical, balance between the activity of ERalpha and ERbeta is what ultimately determines the response of the prostate to estrogen, and is crucial for prostate health.

Perinatal exposure to oestradiol and bisphenol A alters the prostate epigenome and increases susceptibility to carcinogenesis

An important and controversial health concern is whether low-dose exposures to hormonally active environmental oestrogens such as bisphenol A can promote human diseases including prostate cancer. Our studies in rats have shown that pharmacological doses of oestradiol administered during the critical window of prostate development result in marked prostate pathology in adulthood that progress to neoplastic lesions with ageing. Our recent studies have also demonstrated that transient developmental exposure of rats to low, environmentally relevant doses of bisphenol A or oestradiol increases prostate gland susceptibility to adult-onset precancerous lesions and hormonal carcinogenesis. These findings indicate that a wide range of oestrogenic exposures during development can predispose to prostatic neoplasia that suggests a potential developmental basis for this adult disease. To identify a molecular basis for oestrogen imprinting, we screened for DNA methylation changes over time in the exposed prostate glands. We found permanent alterations in DNA methylation patterns of multiple cell signalling genes suggesting an epigenetic mechanism of action. For phosphodiesterase type 4 variant 4 (PDE4D4), an enzyme responsible for intracellular cyclic adenosine monophosphate breakdown, a specific methylation cluster was identified in the 5'-flanking CpG island that was gradually hypermethylated with ageing in normal prostates resulting in loss of gene expression. However, in prostates exposed to neonatal oestradiol or bisphenol A, this region became hypomethylated with ageing resulting in persistent and elevated PDE4D4 expression. In total, these findings indicate that low-dose exposures to ubiquitous environmental oestrogens impact the prostate epigenome during development and in so doing, promote prostate disease with ageing.

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.

Developmental estrogen exposures predispose to prostate carcinogenesis with aging

Prostate morphogenesis occurs in utero in humans and during the perinatal period in rodents. While largely driven by androgens, there is compelling evidence for a permanent influence of estrogens on prostatic development. If estrogenic exposures are abnormally high during the critical developmental period, permanent alterations in prostate morphology and function are observed, a process referred to as developmental estrogenization. Using the neonatal rodent as an animal model, it has been shown that early exposure to high doses of estradiol results in an increased incidence of prostatic lesions with aging which include hyperplasia, inflammatory cell infiltration and prostatic intraepithelial neoplasia or PIN, believed to be the precursor lesion for prostatic adenocarcinoma. The present review summarizes research performed in our laboratory to characterize developmental estrogenization and identify the molecular pathways involved in mediating this response. Furthermore, recent studies performed with low-dose estradiol exposures during development as well as exposures to environmentally relevant doses of the endocrine disruptor bisphenol A show increased susceptibility to PIN lesions with aging following additional adult exposure to estradiol. Gene methylation analysis revealed a potential epigenetic basis for the estrogen imprinting of the prostate gland. Taken together, our results suggest that a full range of estrogenic exposures during the postnatal critical period - from environmentally relevant bisphenol A exposure to low-dose and pharmacologic estradiol exposures - results in an increased incidence and susceptibility to neoplastic transformation of the prostate gland in the aging male which may provide a fetal basis for this adult disease.

Estrogens and mechanisms of prostate cancer progression

Prostate cancer is a major health issue in westernized countries, being considered a prototypical age-related, androgen-dependent tumor. However, data on the association between circulating androgens and prostate cancer have been inconsistent and mostly not compatible with the androgen hypothesis. In addition, plasma androgen-to-estrogen ratio appears to decrease with age, suggesting that estrogens may also have a role. Results from our own and others' studies suggest that circulating steroids cannot be considered representative of their actual intraprostatic levels. This is a consequence of the expression and/or activity of steroid enzymes, including 17beta-hydroxysteroid dehydrogenase (17beta-HSD), 5alpha-reductase, 3alpha/3beta-HSD, and aromatase, which may eventually lead to a differential tissue accumulation of steroid derivatives having distinct biological activities. Interestingly, many of the genes encoding for steroid enzymes are highly polymorphic in nature, although only a few studies have investigated their relation with prostate cancer and the data presently available are inconclusive. Locally produced or metabolically transformed estrogens may differently affect proliferative activity of prostate cancer cells. In our studies, estrogen may either stimulate or decrease prostate cancer cell growth, also depending on the receptor status. In particular, an imbalance of ERalpha and ERbeta expression may be critical to determine the ultimate estrogen effects on prostate cancer cell growth. Furthermore, evidence is accumulating that estrogens regulate gene transcription through an array of estrogen-response elements (EREs) and non-EREs, either ligand-dependent or -independent. This is further complicated by the presence of receptor isoforms, distinct cofactor interaction, and potential heterodimerization. Based on this combined evidence, a hypothetical model of prostate cancer progression is presented.

The role of estrogens in normal and abnormal development of the prostate gland

Estrogens play a physiologic role during prostate development with regard to programming stromal cells and directing early morphogenic events. However, if estrogenic exposures are abnormally high during the critical developmental period, permanent alterations in prostate branching morphogenesis and cellular differentiation will result, a process referred to as neonatal imprinting or developmental estrogenization. These perturbations are associated with an increased incidence of prostatic lesions with aging, which include hyperplasia, inflammation, and dysplasia. To understand how early estrogenic exposures can permanently alter the prostate and predispose it to neoplasia, we examined the effects of estrogens on prostatic steroid receptors and key developmental genes. Transient and permanent alterations in prostatic AR, ERalpha, ERbeta, and RARs are observed. We propose that estrogen-induced alterations in these critical transcription factors play a fundamental role in initiating prostatic growth and differentiation defects by shifting the prostate from an androgen-dominated gland to one whose development is regulated by estrogens and retinoids. This in turn leads to specific disruptions in the expression patterns of key prostatic developmental genes that normally dictate morphogenesis and differentiation. Specifically, we find transient reductions in Nkx3.1 and permanent reductions in Hoxb-13, which lead to differentiation defects particularly within the ventral lobe. Prolonged developmental expression of Bmp-4 contributes to hypomorphic growth throughout the prostatic complex. Reduced expression of Fgf10 and Shh and their cognate receptors in the dorsolateral lobes leads to branching defects in those specific regions in response to neonatal estrogens. We hypothesize that these molecular changes initiated early in life predispose the prostate to the neoplastic state upon aging.

Transient neonatal estrogen exposure to estrogen-deficient mice (aromatase knockout) reduces prostate weight and induces inflammation in late life

Exposure of newborn male mice to estrogens is associated with age-related changes in prostate size and induction of epithelial hyperplasia and dysplasia. Whether these changes directly result from systemic estrogen administration or indirect effects of estrogens on systemic testosterone levels is unclear. We have addressed this question using aromatase-knockout (ArKO) mice that are estrogen-deficient during their lifespan but have elevated androgen levels and develop prostate enlargement and hyperplasia (McPherson SJ, Wang H, Jones ME, Pedersen J, Iismaa TP, Wreford N, Simpson ER, Risbridger GP: Endocrinology 2001, 142:2458-2467). Circulating testosterone and dihydrotestosterone levels were significantly decreased by neonatal diethylstilbestrol treatment, remained suppressed in adult wild-type mice, but rapidly returned to control levels in ArKO animals. However, adult prostate weight and luminal size were reduced in both wild-type and ArKO animals. Because both wild-type and ArKO mice developed epithelial hyperplasia and inflammation following neonatal diethylstilbestrol treatment, this validates that estrogens directly cause prostatic inflammation and epithelial hyperplasia. Furthermore, because ArKO mice are estrogen-deficient, this study demonstrates the sensitivity of the neonatal period to estrogen exposure and the long range and permanent nature of the prostatic responses that occur. Finally, this study establishes the ArKO mouse model of estrogen deficiency as a unique approach to study the effects of estrogens, estrogenic factors, and endocrine disruptors on prostate development.

Regulation of urogenital smooth muscle patterning by testosterone and estrogen during prostatic induction

BACKGROUND

Smooth muscle (SM) has been proposed to play an important role in controlling prostate organogenesis by regulating signaling between inductive mesenchyme and developing epithelial prostatic buds.

METHODS

We have examined the effects of testosterone and estrogen upon SM patterning in the embryonic rat urogenital tract (UGT) using in vitro organ cultures, immunohistochemistry, and Western blotting.

RESULTS

We observed that testosterone elicited a sexually dimorphic difference in SM structure of embryonic UGTs, in cultures grown with testosterone. The addition of estrogen led to an increase in the rate of SM closure, in both males and females. To quantify the effects of steroids upon SM we used Western blotting of SM actin, which showed that estrogen stimulated SM content, while testosterone reduced SM content. Finally, we examined the expression of ERalpha, ERbeta, PR, and SM actin under different hormonal treatments of UGTs grown in vitro. The expression patterns of ERalpha and ERbeta were largely unchanged by hormonal treatment, while PR showed a much broader expression pattern in response to estradiol.

CONCLUSIONS

Our results indicate that testosterone can directly regulate SM patterning and content in the UGT, and that SM is sensitive to both androgens and estrogens.

Reproductive dysgenesis in wildlife: a comparative view

Abnormal reproductive development in males has been linked to environmental contaminant exposure in a wide variety of vertebrates. These include humans, rodent models, and a large number of comparative wildlife species. In human males, abnormal reproductive development can manifest as a suite of symptoms, described collectively as testicular dysgenesis syndrome (TDS). TDS is also described as demasculinization or feminization of the male phenotype. The suite includes cryptorchidism, in situ germ cell carcinoma of the testis and overt testicular cancer, reduced semen quality, and hypospadias. In this paper, we review examples of TDS among comparative species. Wildlife exposed to environmental contaminants are susceptible to some of the same developmental abnormalities and subsequent symptoms as those seen in human males with TDS. There are additional end points, which are also discussed. In some cases, the symptoms are more severe than those normally seen in humans with TDS (i.e. oocytes developing within the testis) because some non-mammalian species exhibit greater innate reproductive plasticity, and are thus more easily feminized. Based on our review, we present an approach regarding the ontogeny of TDS. Namely, we suggest that male susceptibility to the androgynizing influences of environmental contaminants originates in the sexually undifferentiated embryo, which, in almost all species, including humans, consists of bipotential reproductive tissues. These tissues can develop as either male or female and their ultimate direction depends on the environment in which they develop.

Tocopherol-associated protein suppresses prostate cancer cell growth by inhibition of the phosphoinositide 3-kinase pathway

Epidemiologic studies suggested that vitamin E has a protective effect against prostate cancer. We showed here that tocopherol-associated protein (TAP), a vitamin E-binding protein, promoted vitamin E uptake and facilitated vitamin E antiproliferation effect in prostate cancer cells. Interestingly, without vitamin E treatment, overexpression of TAP in prostate cancer cells significantly suppressed cell growth; knockdown of endogenous TAP by TAP small interfering RNA (siRNA) in nonmalignant prostate HPr-1 cells increased cell growth. Further mechanism dissection studies suggested that the tumor suppressor function of TAP was via down-regulation of phosphoinositide 3-kinase (PI3K)/Akt signaling, but not by modulating cell cycle arrest or androgen receptor signaling. Immunoprecipitation results indicated that TAP inhibited the interaction of PI3K subunits, p110 with p85, and subsequently reduced Akt activity. Constitutively active Akt could negate the TAP-suppressive activity on prostate cancer cell growth. Moreover, stable transfection of TAP in LNCaP cells suppressed LNCaP tumor incidence and growth rate in nude mice. Furthermore, TAP mRNA and protein expression levels were significantly down-regulated in human prostate cancer tissue samples compared with benign prostate tissues as measured by reverse transcription-PCR, in situ hybridization, and immunohistochemistry. Together, our data suggest that TAP not only mediates vitamin E absorption to facilitate vitamin E antiproliferation effect in prostate cancer cells, but also functions like a tumor suppressor gene to control cancer cell viability through a non-vitamin E manner. Therefore, TAP may represent a new prognostic marker for prostate cancer progression.

Early effects of estrogen on the rat ventral prostate

Complex interactions between androgen and estrogen (E2) regulate prostatic development and physiology. We analyzed the early effects of a high single dose of E2 (25 mg/kg body weight) and castration (separately or combined) on the adult 90-day-old male Wistar rat ventral prostate. Androgen levels, prostate weight, and the variation in the relative and absolute volume of tissue compartments and apoptotic indices were determined for 7 days. Castration and exogenous E2 markedly reduced ventral prostate weight (about 50% of the control), with a significant reduction in the epithelial compartment and increased stroma. The final volume of the epithelium was identical at day 7 for all treatments (58.5% of the control). However, E2 had an immediate effect, causing a reduction in epithelial volume as early as day 1. An increase in smooth muscle cell volume resulted from the concentration of these cells around the regressing epithelium. The treatments resulted in differential kinetics in epithelial cell apoptosis. Castration led to a peak in apoptosis at day 3, with 5% of the epithelial cells presenting signs of apoptosis, whereas E2 caused an immediate increase (observed on day 1) and a sustained (up to day 7) effect. E2 administration to castrated rats significantly increased the level of apoptosis by day 3, reaching 9% of the epithelial cells. The divergent kinetics between treatments resulted in the same levels of epithelial regression after 7 days (approximately 30% of control). These results show that E2 has an immediate and possibly direct effect on the prostate, and anticipates epithelial cell death before reducing testosterone to levels as low as those of castrated rats. In addition, E2 and androgen deprivation apparently cause epithelial cell death by distinct and independent pathways.

Prostate cancer among pesticide applicators: a meta-analysis

OBJECTIVES

To analyse data from peer-reviewed, case-referent and cohort studies, studying the occurrence of prostate cancer in pesticide applicators and in some other, related, occupational categories, in order to determine a possible relationship of cancer of the prostate with pesticide exposure; to calculate a meta-rate ratio and to compare it with the meta-rate ratios obtained in a previous meta-analysis performed over a shorter time (1995-2001) in a broader exposure category, including many pesticide-related agricultural and non-agricultural occupations.

METHODS

Medline was searched for the years between 1966 and 2003, and relevant studies were identified from 1986 on. We conducted a meta-analysis of 22 studies complying with the inclusion criteria in order to pool their relative risk (RR) estimates. Studies were summarised and assessed for homogeneity and publication bias.

RESULTS

The meta-rate ratio, based on 22 estimates of RR, is 1.24 [95% confidence interval (95% CI) 1.06-1.45]. This pooled risk estimate for the occupational categories selected is higher than the one previously calculated for farmers in general over a shorter period of publication. Substantial heterogeneity of rate ratios exists between the different studies. The major source of heterogeneity identified is geographic location. Increased meta-rate ratios are observed for studies derived from North America as well as from Europe, the meta-rate ratios from Europe being lower than those from North America. There is no obvious indication of publication bias.

CONCLUSION

The increased meta-rate ratio for prostate cancer in agricultural pesticide applications provides additional evidence for a possible relationship between pesticide exposure and prostate cancer. The homogeneity observed between the individual rate ratios, after we had regrouped the data according to geographic location, tends to increase the consistency of the association. However, the data available from the individual studies do not provide sufficient exposure information for firm conclusions to be drawn about pesticide exposure as the cause of prostate cancer, independently from other factors.

Role of estrogens in development of prostate cancer

Estrogens have previously been extensively used in prostate cancer treatment. Serious side effects, primarily in cardiovascular system have, however, limited their use. The therapeutic effect of estrogen in preventing prostate cancer growth was mainly obtained indirectly by feedback inhibition of the hypothalamic release of LRH leading to lowered serum androgen levels and castration like effects. Prostate tissue is also most probably a target for direct regulation by estrogens. Prostate contains estrogen receptor alpha (ERalpha) and beta (ERbeta), which are localized characteristically in stroma and epithelium, respectively. The physiological function of these receptors is not known but there is evidence of the role of estrogens in prostatic carcinogenesis. Developing prostate seems particularly sensitive to increased level of endogenous and/or exogenous estrogens. Perinatal or neonatal exposure of rats and mice to estrogens leads to "imprinting" of prostate associated with increased proliferation, inflammation and dysplastic epithelial changes later in life. Prolonged treatment of adult rodents with estrogens along with androgens also leads to epithelial metaplasia, PIN-like lesions and even adenocarcinoma of prostate speaking for the role of estrogen in prostate cancer development. Recent results concerning antiestrogen inhibition of prostate cancer development beyond PIN-type lesions in transgenic mouse models further suggests a role for estrogens in prostate cancer progression. These results also suggest that direct inhibition of estrogen action at the level of prostate tissue may provide an important novel principle of development of prostate cancer therapies.

Sonic hedgehog-patched Gli signaling in the developing rat prostate gland: lobe-specific suppression by neonatal estrogens reduces ductal growth and branching

While prostate gland development is dependent on androgens, other hormones including retinoids and estrogens can influence this process. Brief exposure to high-dose estrogen during the neonatal period in rats leads to permanent, lobe-specific aberrations in the prostate gland, a phenomenon referred to as developmental estrogenization. We have previously shown that this response is mediated through alterations in steroid receptor expression; however, further downstream mechanisms remain unclear. Herein, we examined Sonic hedgehog (Shh)-patched (ptc)-gli in the developing rat prostate gland, its role in branching morphogenesis, and the effects of neonatal estrogens on its expression and localization to determine whether a disturbance in this signaling pathway is involved in mediating the estrogenized phenotype. Shh was expressed in epithelial cells at the distal tips of elongating ducts in discreet, heterogeneous foci, while ptc and gli1-3 were expressed in the adjacent mesenchymal cells in the developing gland. The addition of Shh protein to cultured neonatal prostates reduced ductal growth and branching, decreased Fgf10 transcript, and increased Bmp4 expression in the adjacent mesenchyme. Shh-induced growth suppression was reversed by exogenous Fgf10, but not noggin, indicating that Fgf10 suppression is the proximate cause of the growth inhibition. A model is proposed to show how highly localized Shh expression along with regulation of downstream morphogens participates in dichotomous branching during prostate morphogenesis. Neonatal exposure to high-dose estradiol suppressed Shh, ptc, gli1, and gli3 expressions and concomitantly blocked ductal branching in the dorsal and lateral prostate lobes specifically. In contrast, ventral lobe branching and Shh-ptc-gli expression were minimally affected by estrogen exposure. Organ culture studies with lateral prostates confirmed that estradiol suppressed Shh-ptc-gli expression directly at the prostatic level. Taken together, the present findings indicate that lobe-specific decreases in Shh-ptc-gli expression are involved in mediating estradiol-induced suppression of dorsal and lateral lobe ductal growth and branching during prostate morphogenesis.

Estrogen enhancement of androgen-responsive gene expression in hormone-induced hyperplasia in the ventral prostate of F344 rats

It has been postulated that, in addition to the crucial role of androgens, estrogens may be involved in development of prostate hyperplasia and cancer. In rats, combined administration of estrogen and androgen synergistically increases ventral prostate weight, and continued treatment results in the development of glandular hyperplasia. Prostate adenocarcinoma can be induced by chemical carcinogens in rats, and estrogen given together with an androgen generally shortens the latent period or increases the incidence and/or multiplicity of carcinomas. However, the mechanisms responsible for these synergistic effects of estrogen and androgen are poorly understood. In the present study, we examined the combined effects of 17beta-estradiol (E2) and testosterone (T) on gene expression in an early stage of prostate hyperplasia in an F344 rat model. ERalpha expression, which has been suggested to contribute to development of prostatic hyperplasia, was increased by the combined treatment with T and E2, while it was suppressed by T alone. Expression levels of two androgen-responsive genes, probasin and kallikrein S3, were increased in the ventral prostate of rats treated with T plus E2 for 4 weeks in a dose-dependent manner, while short-term treatment did not alter the expression. These results suggested that enhancing effects of E2 on transcription of androgen-responsive genes, as well as an increased level of ERalpha may play roles in the synergistic effects of E2 on T-induced prostate hyperplasia.

Loss of ERbeta expression as a common step in estrogen-dependent tumor progression

The characterization of estrogen receptor beta (ERbeta) brought new insight into the mechanisms underlying estrogen signaling. Estrogen induction of cell proliferation is a crucial step in carcinogenesis of gynecologic target tissues, and the mitogenic effects of estrogen in these tissues (such as breast, endometrium and ovary) are well documented both in vitro and in vivo. There is also an emerging body of evidence that colon and prostate cancer growth is influenced by estrogens. In all of these tissues, most studies have shown decreased ERbeta expression in cancer as compared with benign tumors or normal tissues, whereas ERalpha expression persists. The loss of ERbeta expression in cancer cells could reflect tumor cell dedifferentiation but may also represent a critical stage in estrogen-dependent tumor progression. Modulation of the expression of ERalpha target genes by ERbeta or ERbeta-specific gene induction could explain that ERbeta has a differential effect on proliferation as compared with ERalpha. ERbeta may exert a protective effect and thus constitute a new target for hormone therapy, such as ligand specific activation. The potential distinct roles of ERalpha and ERbeta expression in carcinogenesis, as suggested by experimental and clinical data, are discussed in this review.

Lack of modifying effects of 4-ter t-octylphenol and benzyl butyl phthalate on 3,2-dimethyl-4-aminobiphenyl-induced prostate carcinogenesis in rats

The modifying effects of dietary feeding of two estrogenic compounds, 4-tert-octylphenol (tOP) and benzyl butyl phthalate (BBP), on 3,2-dimethyl-4-aminobiphenol (DMAB)-induced prostatic carcinogenesis were investigated in male F344 rats. We also assessed the effects of the test compounds on the proliferating cell nuclear antigen (PCNA) index in induced neoplasms, prostatic intra-epithelial neoplasm (PIN), and non-lesional glands in the prostate. To induce prostatic neoplasms, rats were given subcutaneous injections of DMAB (25 mg/kg body weight) every other week, 10 times in total. They also received the experimental diet containing 10 or 100 ppm tOP and BBP for 40 weeks, starting 1 week after the last dosing of DMAB. DMAB exposure produced prostatic adenocarcinoma with an incidence of 41.2% at the end of the study (week 60). Dietary administration of tOP and BBP did not affect the incidence of prostatic adenocarcinoma: 43.8% in the DMAB --> 10 ppm tOP group; 25.0% in the DMAB --> 100 ppm tOP group; 43.8% in the DMAB --> 10 ppm BBP group; and 43.8% in the DMAB --> 100 ppm BBP group. The PCNA indices in adenocarcinomas, PIN, and non-lesional glands in rats treated with DMAB and tOP or BBP were slightly lower than that of the DMAB alone group, but the differences were not statistically significant. These results might suggest that dietary feeding of the estrogenic compounds tOP and BBP did not modulate DMAB-induced prostatic carcinogenesis in rats.

Human prostate cancer risk factors

Prostate cancer has the highest prevalence of any nonskin cancer in the human body, with similar likelihood of neoplastic foci found within the prostates of men around the world regardless of diet, occupation, lifestyle, or other factors. Essentially all men with circulating androgens will develop microscopic prostate cancer if they live long enough. This review is a contemporary and comprehensive, literature-based analysis of the putative risk factors for human prostate cancer, and the results were presented at a multidisciplinary consensus conference held in Crystal City, Virginia, in the fall of 2002. The objectives were to evaluate known environmental factors and mechanisms of prostatic carcinogenesis and to identify existing data gaps and future research needs. The review is divided into four sections, including 1) epidemiology (endogenous factors [family history, hormones, race, aging and oxidative stress] and exogenous factors [diet, environmental agents, occupation and other factors, including lifestyle factors]); 2) animal and cell culture models for prediction of human risk (rodent models, transgenic models, mouse reconstitution models, severe combined immunodeficiency syndrome mouse models, canine models, xenograft models, and cell culture models); 3) biomarkers in prostate cancer, most of which have been tested only as predictive factors for patient outcome after treatment rather than as risk factors; and 4) genotoxic and nongenotoxic mechanisms of carcinogenesis. The authors conclude that most of the data regarding risk relies, of necessity, on epidemiologic studies, but animal and cell culture models offer promise in confirming some important findings. The current understanding of biomarkers of disease and risk factors is limited. An understanding of the risk factors for prostate cancer has practical importance for public health research and policy, genetic and nutritional education and chemoprevention, and prevention strategies.

Endocrine disruption and hypospadias

The complexity of human biology makes it impossible to know for certain if endocrine disruption accounts for human penile deformities. Toxicologists point out that an overall assessment of risk must include other factors in addition to exposure including absorption, metabolism, excretion, bioaccumulation and other chemical interactions (Harrison et al., 1997). Many skeptics observe lack of analytic ability to document contaminant levels during critical windows of exposure (Safe, 2000). Further, the environmental estrogens studied (DDT, PCB and bis-phenol A) are quite weak compared to the well studied potent estrogen DES which did not cause penile deformities (Joffe, 2001). While environmental estrogens may be unlikely in contributing to penile deformities, the antiandrogens (phthalates, vinclozolin and DDE) are more plausible is this regard, as maleness is critically dependent upon androgen action. Observers note that, in general, the environmental concentrations of persistent organochlorine compounds have been decreasing over the past two decades. Some feel that our current levels of exposure are too low and the potency of the anti-androgens too weak to account for any significant developmental genital effect (Williams et al., 2001). Caution and restraint are always reasonable in matters of data intrepretation. Past researchers were reassured that pthtalate esters were quite safe when they first were assessed for possible harmful effects on male fertility. Unfortunately it took different models, analyzing transgenerational effects, before it became crystal clear that these compounds can dramatically affect male genital development following experimental maternal exposure at dosages and concentrations currently present in most women. We can not now be so reassured that our male development is unaffected by any of the over 65,000 manmade organochlorine compounds on the planet. Multiple observations from diverse disciplines provide credible evidence that proliferation of xenobiotic chemicals can cause potentially disastrous unintended consequences for the male gender, and upon reflection, our species.

Identification of genes involved in estrogenic action in the human prostate using microarray analysis

Estrogens have profound effects on the developing prostate and are suspected to contribute to the development of benign prostatic hyperplasia, but the mechanism by which this hormone elicits its regulatory function still remains largely unknown. Using complementary RNA microarrays comprising approximately 10,000 oligonucleotide gene targets we compared differences in mRNA expression of estradiol-treated and untreated prostatic stromal cells in vitro. Based on a threshold of greater than twofold change, 228, 241, and 464 of the expressed genes were found to be regulated by estradiol after 10, 24, and 48 h of treatment, respectively. The secondary analysis of one estradiol-activated transcript, namely lipopolysaccharide-binding protein, and four estradiol-repressed genes, namely ras homolog gene family member E (RhoE/Rnd3), ubiquitin thiolesterase, interleukin 6, and interleukin 8 (IL-8), by real-time quantitative PCR confirmed the results of the microarray analysis. Moreover, IL-8 and RhoE were found to be down-regulated by estradiol at the protein level as well. We identified a set of genes involved in a wide range of cellular functions that are potentially important for understanding the molecular basis of estradiol action in the prostate.

Effects of endocrine disrupting compounds on the pathology and oestrogen receptor alpha and beta distribution in the uterus and cervix of ewe lambs

A number of chemicals have been classed as endocrine disrupting compounds due to their ability to mimic the actions of endogenous hormones in vivo and in vitro. The objective of this experiment was to determine the pathological changes and oestrogen receptor (ER) distribution in the cervix and uterus of prepubertal ovariectomised ewe lambs following exposure to a range of compounds with a predominantly oestrogenic effect. Lambs were exposed to diethylstilbestrol (0.175 mg/kg biweekly), bisphenol-A (3.5mg/kg biweekly) or octylphenol (3.5mg/kg biweekly) for 6 weeks. Following sacrifice, uterine and cervical tissue pathology was assessed. The endometrial and myometrial areas were quantified and the distribution of ERalpha and ERbeta assessed by immunohistochemistry. No differences were observed between control and octylphenol-exposed lambs in uterine gross pathology and histopathology. Uteri from bisphenol-A- and diethylstilbestrol-exposed lambs were heavier than both control and octylphenol-exposed lambs. In the bisphenol-A-exposed lambs, endometrial oedema accounted for a significant increase in the endometrial cross-sectional area over the other groups. Uteri from animals exposed to diethylstilbestrol showed variable pathology including oedema and cellular proliferation. Keratinisation of the cervical epithelium was observed in both bisphenol-A- and diethylstilbestrol-exposed lambs. Exposure to diethylstilbestrol and bisphenol-A was associated with a diffuse intracellular distribution of ERalpha and ERbeta in the uterine endometrium. This was in addition to the strong cytoplasmic staining of uterine epithelial cells and nuclear staining of specific sub-epithelial cells observed in all groups. We conclude that a 6-week exposure of lambs to bisphenol-A and diethylstilbestrol altered the uterocervical environment and has the potential to disrupt subsequent reproductive function. Pathological changes could not be detected in the uterus or cervix of lambs exposed to octylphenol.

Occupation related pesticide exposure and cancer of the prostate: a meta-analysis

AIMS

To summarise recent literature on the risk of prostate cancer in pesticide related occupations, to calculate the meta-rate ratio, and to compare it to data from meta-analyses previously published.

METHODS

A meta-analysis of 22 epidemiological studies, published between 1995 and 2001, was conducted in order to pool their rate ratio estimates. Studies were summarised and evaluated for homogeneity and publication bias.

RESULTS

The meta-rate ratio estimate, based on 25 estimators of relative risk from 22 studies, was 1.13 (95% CI 1.04 to 1.22). Significant heterogeneity of rate ratios existed among the different studies. Therefore, a stratified analysis was carried out. Major sources of heterogeneity identified were geographic location, study design, and healthy worker effect. Overall, pooled risk estimates for studies derived from Europe were lower than those derived from the USA/Canada. A significant increase in rate ratio was observed for the occupation category of pesticide applicators, whereas no significant increase was observed for farmers. There was no evidence of publication bias.

CONCLUSION

This increased meta-rate ratio for prostate cancer in different pesticide related occupations, including farmers, is very similar to three, previously published, meta-rate ratios for prostate cancer in farmers calculated from studies published before 1995. Although the underlying data do not identify pesticide exposure as an independent cause for prostate cancer, the fact that an increased meta-rate ratio is again obtained points to occupational exposure to pesticides as a possible factor. Future epidemiological studies should focus, as far as possible, on reliable methods to estimate actual exposure.