Involution Of Prostate Research Articles

Post-castration prostatic involution: A morphometric and endocrine study of healthy canines and those with benign prostatic hyperplasia.

The objective of this study was to evaluate the effect of castration on dimensions of the prostate by B-mode ultrasound for 90days, as well as to evaluate changes in serum concentrations of testosterone and oestradiol in clinically healthy canines and those with benign prostatic hyperplasia (BPH). Three groups of animals were used: healthy canines castrated on day 0 (HCC, n=8), canines with a diagnosis of benign prostatic hyperplasia (BPHC, n=9) castrated on day 0 and healthy uncastrated canines (IHCC, n=10). Prostate size was obtained by B-mode ultrasound, while blood samples were collected (days 0, 7, 14, 28, 60 and 90 post-castration) to determine the serum testosterone and oestradiol concentration. Castration did not affect serum oestradiol concentrations. Castration led to a decrease in serum testosterone (reaching values <20ng/dl in the first week, p<.05), causing a gradual decrease in dimensions of prostate parameters relative to body weight (p<.05). Canines with BPHC had similar prostate dimensions as the IHCC group 2weeks post-castration. In relation to the prostate's relative parameters, the decrease with time was greater in canines with BPHC than those in the HCC group. When evaluating parameters as a percentage of relative change, the decrease with time was similar in both castrated groups, except for relative length percentage, which presented a more pronounced decline in BPHC canines than HCC canines. In conclusion, castration is an effective, fast and long-lasting treatment for canine patients with BPH, as it causes a rapid decrease in blood testosterone concentrations and a decrease in glandular volume, but does not affect serum oestradiol concentrations. This study did not determine the mechanisms of action, but allowed us to observe (based on morphometric variables) that characteristics of prostate involution after castration differed between canines with BPH and healthy canines.

\u201cProstate telocytes change their phenotype in response to castration or testosterone replacement\u201d

Telocytes are CD34-positive cells with a fusiform cell body and long, thin cytoplasmic projections called telopodes. These cells were detected in the stroma of various organs, including the prostate. The prostate is a complex gland capable of undergoing involution due to low testosterone levels; and this condition can be reversed with testosterone replacement. Telocyte function in the mature prostate remains to be dermined, and it is not known whether telocytes can take place in tissue remodeling during prostate involution and regrowth. The present study employed structural, ultrastructural and immunohistochemical methods to investigate the telocyte’s phenotypes in the ventral prostate (VP) from control (CT), castrated (CS) and testosterone replacement (TR) groups of adult male Wistar rats. Telocytes were found in the subepithelial, perimuscular and interstitical regions around glandular acini. Telocytes from CT animals have condensed chromatin and long and thin telopodes. In CS group, telocytes appeared quiescent and exhibited layers of folded up telopodes. After TR, telocytes presented loose chromatin, abundant rough endoplasmic reticulum and enlarged telopodes, closely associated with bundles of collagen fibrils. We called these cells “telocytes with a synthetic phenotype”. As testosterone levels and glandular morphology returned toward to the CT group parameters, after 10 days of TR, these telocytes progressively switched to the normal phenotype. Our results demonstrate that telocytes exhibit phenotypic plasticity upon androgen manipulation and interact with fibroblast and smooth muscle cells to maintain glandular architecture in control animals and during tissue remodeling after hormonal manipulation.

A folic acid-enriched diet attenuates prostate involution in response to androgen deprivation.

Serum folate concentrations in the United States have risen since dietary folic acid fortification was first mandated in 1998. Although maternal folic acid offers protection against neural tube defects in conceptuses, its impact on other organ systems and life stages have not been fully examined. Here, we used a mouse model to investigate the impact of a Folic acid (FA) enriched diet on prostate homeostasis and response to androgen deprivation. Male mice were fed a control diet (4 mg FA/kg feed) or a folic acid supplemented diet (24 mg FA/kg feed) beginning at conception and continuing through early adulthood, when mice were castrated. We made the surprising observation that dietary FA supplementation confers partial resistance to castration-mediated prostate involution. At 3, 10, and 14 days post-castration, FA enriched diet fed mice had larger prostates as assessed by wet weight, taller prostatic luminal epithelial cells, and more abundant RNAs encoding prostate secretory proteins than castrated control diet fed mice. Diet did not significantly affect prostate weights of intact mice or serum testosterone concentrations of castrated mice. RNA-Seq analysis revealed that the FA enriched diet was associated with a unique prostate gene expression signature, affecting several signaling and metabolic pathways. Continuous exposure to a FA enriched diet slows prostate involution in response to androgen deprivation. Prostates from FA diet mice have increased secretory gene expression and increased luminal cell heights. The influence of dietary FA supplementation on the prostate response to androgen deprivation raises a future need to consider how dietary folic acid supplementation affects efficacy of androgen-reducing therapies for treating prostate disease.

Benigne prostate hyperplasya and&#x0D; adenocarcinoma: the role of signal molecules for diagnostics and therapy in patients of various age

In the last years, new data on the role of microenvironment in involution of prostate cells (fibroblasts) and age-associated prostate oncogenesis have been obtained. The goal of this work is the investigation of expression of prostate fibroblasts, CXCL12, SDC1 proteins and hormones in normal and pathological prostate in subjects o different age. Materials were obtained from 78 patients with benignant prostate hyperplasia (BPH), 96 patients with prostate adenocarcinoma and 52 dead men without prostate pathology. All subjects were divided in 3 age groups (middle aged, elderly, and old) and investigated by electron, confocal and light microscopy and immunohistochemical methods. It was shown, that CXCL12 hyperexpression was characteristic of BPH and adenocarcinoma; this correlation became more pronounced with age. SDC1 expression in normal prostate decreased with age which may suggest age-related prostate involution. SDC1 expression in adenocarcinoma increased with. A slight decrease of chromogranin A and somatostatin expression was associated with normal prostate ageing. This process increased in BPH and prostate carcinoma. Chromogranin A and somatostatin decrease correlated with prostate ageing and oncopathology.

ARV-330: Androgen receptor PROTAC degrader for prostate cancer.

267 Background: The transition from localized prostate cancer to metastatic disease often involves modulation of the Androgen Receptor (AR). During the disease progression, patients progressing on enzalutamide or abiraterone therapy exhibit amplified AR, increased intra-tumoral androgen production or AR mutations leading to promiscuity to other ligands. Therefore, AR is still the principal driver of the disease. Methods: A novel approach to block AR signaling is to specifically target AR for degradation. To this end, we have developed the PROteolysis TArgeting Chimera (PROTAC) technology that employs hetero-bifunctional small molecules that simultaneously bind VHL E3 ubiquitin ligase and a target of interest (e.g. AR). Due to induced proximity between VHL and AR, an AR PROTAC leads to ubiquitination and subsequent degradation of AR. Results: Our lead AR PROTAC, ARV-330, degrades 92-98% of total AR in all cell lines tested, with 50% degradation concentrations (DC50) &lt; 1nM. AR degradation suppresses the AR-target gene PSA expression, inhibits proliferation, and induces potent apoptosis in VCaP cells with maximal apoptosis observed at 20 nM. While enzalutamide loses its activity in the presence of &gt; 0.5 nM R1881, ARV-330 maintains its activity. In cells containing the ARF876L mutation, enzalutamide is an agonist; however, ARV-330 remains effective. In fact, ARV-330 is able to degrade all clinically relevant AR mutations. ARV-330 exhibits good pharmacokinetic properties, with t1/2 values of several hours and bioavailability of &gt; 80% after sc injection. Treatment of mice with ARV-330, at doses ranging from 0.3 to 10 mg/kg, results in reduction of AR protein levels. The in vitro potency translates into in vivo efficacy, as ARV-330 demonstrates prostate involution in intact mice. In castrated mice implanted with VCaP tumors, ARV-330 shows robust reduction of plasma PSA and blockade of tumor growth. Conclusions: In summary, the AR PROTAC ARV-330 removes AR from prostate cancer cells in a potent manner and produces therapeutic effects as a result. This cellular efficacy has translated into biomarker activity and efficacy in animal models, and ARV-330 is now in preclinical development.

Abstract PR08: ARV-330: An androgen receptor PROTAC degrader for prostate cancer

Abstract Patients with prostate cancer who progress on therapy often have enhanced Androgen Receptor (AR) signaling due to several mechanisms: increased androgen production, increased AR expression, and/or specific AR mutations that render current therapies ineffective. A novel approach to block AR signaling is to specifically target AR for degradation. To do this, we have created AR PROTACs (PROtein-TArgeting Chimeras), bi-functional molecules that have an AR binding moiety on one end and an E3 ligase-recruiting element on the other end, which leads to AR ubiquitination and degradation. We have applied this technology to determine whether it could address mechanisms of resistance to current therapy in prostate cancer models. Our lead AR PROTAC, ARV-330, degrades AR in LNCaP and VCaP cells with 50% degradation concentrations (DC50s) &amp;lt; 1nM. AR degradation had functional consequences in cells, suppressing the AR target gene PSA, inhibiting proliferation, and potently inducing apoptosis in VCaP cells, with maximal apoptosis observed around 20 nM, versus 1 uM for enzalutamide. While both ARV-330 and enzalutamide block proliferation of VCaP cells in response to 0.1 nM of the AR agonist R1881, enzalutamide lost antiproliferative potency with increasing R1881 concentrations, whereas ARV-330 maintained antiproliferative effects. In cells containing the ARF876L mutation, enzalutamide was ineffective; however, ARV-330 maintained complete effectiveness. In mice, ARV-330 exhibited good pharmacokinetic properties, with t1/2 values of several hours and bioavailability of &amp;gt;80% after sc injection. Treatment of mice with ARV-330, at doses ranging from 0.3 to 10 mg/kg, resulted in reduction of AR protein levels and prostate involution in normal mice and, in mice implanted with VCaP tumors, reduction in plasma PSA and blockade of tumor growth. In summary, the AR PROTAC ARV-330 removes AR from prostate cancer cells in a potent manner and produces therapeutic effects as a result. This cellular efficacy has translated into biomarker activity and efficacy in animal models, and ARV-330 is now in preclinical development. Thus, targeted degradation of AR may provide a novel mechanism for providing efficacious therapy for patients with prostate cancer for whom current therapies have failed. Citation Format: James D. Winkler, Meizhong Jin, Andy P. Crew, AnnMarie K. Rossi, Ryan R. Willard, Hanqing Dong, Kam Siu, Jing Wang, Deborah A. Gordon, Xin Chen, Caterina Ferraro, Craig M. Crews, Kevin Coleman, Taavi K. Neklesa. ARV-330: An androgen receptor PROTAC degrader for prostate cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr PR08.

Abstract LB-097: Targeted degradation of the androgen receptor in prostate cancer

Abstract Progression of prostate cancer in patients treated with anti-androgen therapy usually involves several mechanisms of enhanced Androgen Receptor (AR) signaling, including increased intratumoral androgen synthesis, increased AR expression and AR mutations. We have developed a protein degradation technology called PROTACs (PROteolysis TArgeting Chimera), which uses bi-functional molecules that simultaneously bind a target of choice and an E3 ligase. PROTACs, via induced proximity, cause ubiquitination and degradation of the targeted, pathological protein. As opposed to traditional target inhibition, which is a competitive process, degradation is a progressive process. As such, it is less susceptible to increases in endogenous ligand, target expression, or mutations in the target. Thus this technology seems ideal for addressing the mechanisms of AR resistance in patients with prostate cancer. AR PROTACs were shown to degrade AR in LNCaP and VCaP cells, with low nM to pM potency, and had a &amp;gt;85% reduction in AR concentration (Dmax). Degradation was rapid, with 50% of AR lost within 15 minutes and maximal degradation observed by 4 hours. The degradation process in cells was specific, as the PROTAC activity can be competed with excess E3 ligand and PROTACs with an inactive epimer for E3 ligase binding did not degrade AR. AR PROTACs induced rapid apoptosis and cell death in VCaP cells. In LNCap and VCaP cell systems, AR PROTACs were anti-proliferative under conditions in which enzalutamide was inactive, such as increasing concentrations of the AR agonist R1881 and cells containing the ARF876L mutation. AR PROTACs typically exhibited good pharmacokinetic properties, with t1/2 values of several hours and bioavailability of &amp;gt;50% after ip or sc injection. In mice, AR PROTACs demonstrate in vivo activity, including reduction of AR protein levels, prostate involution and tumor growth inhibition. In summary, PROTACs designed to degrade AR are potent, specific, active in vitro and in vivo, and have cellular efficacy superior to enzalutamide. Targeted degradation of AR may provide a novel mechanism for providing efficacious therapy for patients with prostate cancer for whom current therapies have failed. Citation Format: Meizhong Jin, James D. Winkler, Kevin Coleman, Andrew P. Crew, AnnMarie K. Rossi, Ryan R. Willard, Hanqing Dong, Kam Siu, Jing Wang, Deborah A. Gordon, Xin Chen, Caterina Ferraro, Craig M. Crews, Taavi K. Neklesa. Targeted degradation of the androgen receptor in prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-097. doi:10.1158/1538-7445.AM2015-LB-097

The approaches to the optimization of forensic medical methods employed for determining age

The analysis of the results of investigations performed at M.I. Raisky Department of Forensic Medicine, Saratov State Medical University, to elucidate the age-specific changes in the human soft tissues made it possible to distinguish several variants of reducing errors committed in association with the determination of the age of individual subjects with the help of forensic medical methods. At present, the chronological age is calculated with a different degree of accuracy from the data on the involution of aorta, skin, testicles, prostate and thyroid glands. In order to enhance the accuracy of newly developed diagnostic methods, it is proposed to take into account the necessity of fulfilling the following conditions: to increase the number of characteristics of the study object to be analysed, to use the complex of involution features of several organs belonging to a single body system, and to apply the rational approach to the choice of the methods for the mathematical analysis of the data being obtained.

Surgical Stress Delays Prostate Involution in Mice

Androgens control growth of prostate epithelial cells and androgen deprivation induces apoptosis, leading to prostate involution. We investigated the effects of surgical stress on prostate involution induced by androgen ablation and determined the underlying mechanisms. Androgen ablation in mice was induced by surgical castration and administration of the anti-androgenic drugs bicalutamide and MDV3100. Surgical stress was induced by sham castration under isoflurane anesthesia. Surgical stress delayed apoptosis and prostate involution induced by anti-androgenic drugs. These effects of stress were prevented by administering the selective beta2-adrenoreceptor antagonist ICI118,551 and were also blocked in BAD3SA/WT mice expressing phosphorylation-deficient mutant BAD3SA. These results indicate that apoptosis and prostate involution in response to androgen ablation therapy could be delayed by surgical stress via the beta2-adrenoreceptor/BAD signaling pathway. Thus, surgery could interfere with androgen ablation therapy, whereas administration of beta2-adrenoreceptor antagonists may enhance its efficacy.

Abstract B68: The microenvironment decides how prostate tumors respond to castration treatment

Abstract Although androgen deprivation is the standard therapy for metastatic prostate cancer the mechanisms for the initial response and subsequent relapse are largely unknown. The stroma and vasculature are necessary for castration-induced involution of the normal prostate, and androgen-independent tumors respond to castration when surrounded by normal prostate tissue. This suggests that the microenvironment is highly important for the therapeutic effect of castration. To further explore this, androgen-sensitive rat prostate tumor cells (Dunning G) were injected into the rat prostate and/or bone marrow (to simulate bone metastasis) and analyzed for response to castration. Tumors in the prostate responded well to castration with decreased tumor size, both in already established tumors and when tumor cells were injected in castrated animals. The size of bone metastases was, however, unaffected by castration. Both groups developed lung metastasis but castration tended to increase rather than decrease pulmonary tumor burden. To further explore the mechanisms behind this we have established in vitro cell lines from bone metastasis of both castrated and control rats. In our ongoing experiments we are examining if these cells are responsive to castration if instead placed within the prostate environment or if the resistance to therapy has become stable. The response to castration is also further explored in lung metastasis. Our results suggest that the metastatic environment is highly important for the establishment of castration resistant prostate cancer and that the mechanisms behind this need to be further explored. Citation Format: Sofia Halin Bergström, Stina Rudolfsson, Tove Dahl Scherdin, Anders Bergh. The microenvironment decides how prostate tumors respond to castration treatment [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr B68.

Prostatic Involution After Intraprostatic Injection of Cobra Toxin

We evaluated the comparative effects of intraprostatic injection of cobra cardiotoxin D and botulinum toxin type A on prostate structure in the rat model. A total of 18 Sprague-Dawley® rats weighing 500 to 600 gm received a single 0.1 ml injection of saline (6), botulinum toxin type A (6) or the cardiotoxin D (6) component of cobra (Naja naja atra) toxin in the right and left ventral lobes of the prostate. At 14 days the rats were sacrificed. The prostate glands were harvested, weighed and processed for immunohistochemical and morphological studies. Prostate glands injected with cardiotoxin D showed significantly decreased weight compared to that of prostates injected with botulinum toxin type A and the saline control. Prostatic atrophy in the glandular component with flattening of the epithelial lining was seen histologically in rats that received botulinum toxin and cardiotoxin D. Each group injected with cardiotoxin D and botulinum toxin showed a significant increase in the number of apoptotic cells compared with controls while only the botulinum toxin group showed a significant increase in the number of proliferating cells. Only rats injected with botulinum toxin had body weight loss. Our study shows that intraprostatic injection of cobra cardiotoxin D induces prostatic atrophy and leads to a decrease in prostatic weight greater than that of intraprostatic injection of botulinum toxin type A. No systemic effects, such as decreased body weight, were noted after cardiotoxin D injection. Further studies are warranted but the statistically significant decrease in the number of proliferating cells implies a prolonged effect of cardiotoxin D.

Stromal remodelling is required for progressive involution of the rat ventral prostate after castration: Identification of a matrix metalloproteinase‐dependent apoptotic wave

Prostate epithelial-cell apoptosis occurs in response to androgen deprivation. We have hypothesized that continued regression would require stromal changes. Studying apoptosis kinetics up to the 14th day after castration, we identified successive waves of apoptosis, with a prominent peak on day 11. This peak was associated with caspase-3 activity, nuclear translocation of apoptosis-inducing factor and clusterin expression. The apoptosis peak on day 11 was preceded by increased MMP-2 and MMP-7 activation, and MMP-9 expression on days 9 and 10. Treatment with the matrix metalloproteinases inhibitors doxycyclin, hydrocortisone, or GM6001 caused significant reduction in the apoptosis rate on day 11. The present data demonstrate that prostatic epithelial-cell deletion at the 11th day after castration was induced by focal degradation of the extracellular matrix associated with stromal remodelling.

Intraprostatic Botulinum Toxin Type A injection in patients with benign prostatic enlargement: duration of the effect of a single treatment

BackgroundBotulinum Toxin Type-A (BoNT/A) intraprostatic injection can induce prostatic involution and improve LUTS and urinary flow in patients with Benign Prostatic Enlargement (BPE). However, the duration of these effects is unknown. The objective of this work was to determine the duration of prostate volume reduction after one single intraprostatic injection of 200U of Botulinum Toxin Type-A.MethodsThis is an extension of a 6 month study in which 21 frail elderly patients with refractory urinary retention and unfit for surgery were submitted to intraprostatic injection of BoNT/A-200U, by ultrasound guided transrectal approach. In spite of frail conditions, eleven patients could be followed during 18 months. Prostate volume, total serum PSA, maximal flow rate (Qmax), residual volume (PVR) and IPSS-QoL scores were determined at 1, 3, 6, 12 and 18 months post-treatment.ResultsMean prostate volume at baseline, 82 ± 16 ml progressively decreased from month one coming to 49 ± 9,5 ml (p = 0,003) at month six. From this moment on, prostate volume slowly recovered, becoming identical to baseline at 18 months (73 ± 16 ml, p = 0.03). Albeit non significant, serum PSA showed a 25% decrease from baseline to month 6. The 11 patients resumed spontaneous voiding at month one. Mean Qmax was 11,3 ± 1,7 ml/sec and remained unchanged during the follow-up period. PVR ranged from 55 ± 17 to 82 ± 20 ml and IPSS score from10 to 12 points.ConclusionIntraprostatic BoNT/A injection is safe and can reduce prostate volume for a period of 18 months. During this time a marked symptomatic improvement can be maintained.

Androgen sensitivity of prostate epithelium is enhanced by postnatal androgen receptor inactivation

Postnatal inactivation of epithelial androgen receptor (AR) in prostate epithelial AR knockout (PEARKO) mice results in hindered differentiation but enhanced proliferation of epithelial cells. As this resembles the precancerous proliferative atrophy of human prostates with undifferentiated but intensively replicating epithelial cells, we utilized the PEARKO mice to characterize the epithelial response to castration-induced involution with a focus on identifying the potential role of stromal AR and responsiveness of the androgen-deprived epithelia to the aromatizable androgen testosterone (T) or its nonaromatizable metabolite dihydrotestosterone (DHT). PEARKO and littermate control mice were orchidectomized at 8 wk of age and treated 2 wk later with subdermal implantation of 1-cm Silastic tubing filled with T or DHT for a week. Following castration, the prostatic involution and epithelial apoptosis did not significantly differ between control (intact AR) and PEARKO (only stromal AR) males, demonstrating that prostate epithelial involution following castration is mediated primarily via stromal AR-dependent apoptotic signals. Androgen replacement (T/DHT) for 7 days induced significant growth and epithelial proliferation in all prostate lobes in both control and PEARKO, but full regrowth was observed only in controls treated with T. In PEARKO, prostate androgen (T and DHT) treatment induced significant epithelial cell "shedding" into the lumen, with T treatment resulting in acinar disorganization, cyst formation, and aberrant epithelial structures, described as a "gland within a gland." These data suggest that epithelial AR inactivation during postnatal prostate development sensitizes prostate epithelial cells to paracrine signaling mediated by stromal AR activity leading to indirectly androgen-induced epithelial hyperproliferation and formation of epithelial hyperplastic cysts by aromatizable androgens.

Changes in gene expression following androgen receptor blockade is not equivalent to androgen ablation by castration in the rat ventral prostate

Involution of the rat ventral prostate and concomitant modulation of gene expression post-castration is a well- documented phenomenon. While the rat castration model has been extensively used to study androgen regulation of gene expression in the ventral prostate,it is not clear whether all the gene expression changes post-castration are due to androgen depletion alone. To obtain insights into this, we performed differential display reverse transcriptase polymerase chain reaction (DD-RT-PCR) which resulted in the identification of castration and/or flutamide-regulated genes in the rat ventral prostate. These include clusterin, methionine adenosyl transferase II alpha, and prostate-specific transcripts such as PBPC1BS, S100RVP and A7. While clusterin, PBPC1BS and methionine adenosyl transferase II alpha are regulated by both castration and flutamide, S100 RVP and A7 are regulated by castration alone. Interestingly, we show that flutamide, unlike castration, does not induce apoptosis in the rat ventral prostate epithelium, which could be an underlying cause for the differential effects of castration and flutamide treatment. We propose that castration leads to enrichment and depletion of stromal and epithelial cell types, respectively, resulting in erroneous conclusions on some of the cell type-specific transcripts as being androgen regulated.

Expression profiling of the mouse prostate after castration and hormone replacement: implication of H-cadherin in prostate tumorigenesis

Mice have been used extensively for studying normal prostate development and for generation of transgenic or knock-out prostate cancer animal models. To understand systematically and thoroughly the androgen responsive program in the mouse prostate, we carried out microarray analysis to profile gene expression changes during prostate involution and re-growth triggered by castration and subsequent hormone replacement. Genes with significant changes in these two processes were identified and gene ontology analyses revealed that they were mainly involved in response mechanisms, cell adhesion, metabolism, protein metabolism, and cell-cycle progression. The changes observed during prostate involution were largely reversed during re-growth. Sixty-four genes, including Nkx3.1 and probasin, and 65 other genes, including insulin-like growth factor binding protein 3 and H-cadherin (H-Cad), were further identified respectively as androgen-responsive genes and genes inversely correlated with androgen, based on their down- or up-regulation following castration and up- or down-regulation following androgen replacement. Potential androgen-responsive elements were found in the 5′ upstream promoter region of 47 of those 65 genes, suggesting a potential suppression mechanism by androgen receptor. Of these, the role of H-Cad in tumorigenesis was further evaluated. Reduction of H-Cad transcript level was found in the majority of human prostate cancer cell lines and prostatic adenocarcinoma samples examined. Furthermore, induced H-Cad expression in DU145 cells, and knock-down of H-Cad expression in BPH1 cells inhibited and facilitated tumorigenicity, respectively. Taken together, our study provides a molecular understanding of the mouse prostate involution and re-growth processes and identifies a set of genes that are inversely correlated with androgen and may be potentially suppressive for tumorigenesis.

Inhibition of the epidermal growth factor receptor enhances castration‐induced prostate involution and reduces testosterone‐stimulated prostate growth in adult rats

The epidermal growth factor receptor (EGFR) mediates regulatory signals in the normal prostate, but the functional importance of this is unclear. Adult male rats were castrated, or castrated + treated with gefitinib (Iressa, ZD1839), an EGFR tyrosine kinase inhibitor, for 3 days. Seven-day castrated rats were treated with testosterone, or testosterone + gefitinib, for 3 days. Both castration alone and testosterone treatment in castrated animals increased the mRNA and protein levels of EGFR and phospho-EGFR in the ventral prostate. Inhibition of EGFR during castration and during testosterone-stimulated prostate growth resulted in a decrease in total epithelial weight, epithelial cell proliferation, endothelial cell proliferation, and increased epithelial cell apoptosis. This study suggests that increased EGFR signaling during castration mediates stimulatory effects balancing castration-induced prostate regression, and that EGFR signaling is a necessary component in testosterone-stimulated prostate growth.

Androgen‐insensitive prostate cancer cells transiently respond to castration treatment when growing in an androgen‐dependent prostate environment

Castration-induced involution of the normal prostate is caused by primary effects in the prostate stroma and vasculature, but if this is the case also in tumors is unknown. Androgen-independent AT-1 prostate tumor cells were therefore injected into the ventral prostate (VP) in Copenhagen rats. Seven days later when the growing tumor was surrounded by normal VP tissue the rats were castrated and the effect examined 3 and 7 days later. Castration reduced vascular density in the surrounding VP tissue and this was accompanied by tumor cell hypoxia, apoptosis, and temporarily retarded tumor growth. Castration-induced VP tissue regression occurred more rapidly in the contra-lateral than in the tumor-bearing lobe. Androgen-independent tumor cell respond to castration when growing in an androgen-dependent environment. The presence of a tumor influences the castration response in the surrounding normal tissue. The microenvironment determines how prostate epithelial cells respond to castration.

Inhibitory Effects of Castration in an Orthotopic Model of Androgen-Independent Prostate Cancer Can Be Mimicked and Enhanced by Angiogenesis Inhibition

Today, the most important treatment of advanced prostate cancer is castration; unfortunately, however, the long-term effect of this therapy is insufficient. Recent studies suggest that castration-induced prostate involution could be caused by primary effects in the prostate vasculature; therefore, we examined if antivascular treatments could mimic the effects of castration. Androgen-independent AT-1 prostate cancer cells were grown inside the ventral prostate in adult rats. Tumor-bearing animals were treated with an inhibitor of vascular endothelial growth factor receptor 2 and epidermal growth factor receptor signaling, N-(4-bromo-2-fluorophenyl)-6-methoxy-7-[(1-methylpiperidin-4-yl)methoxy]quinazolin-4-amine (ZD6474, AstraZeneca, Södertälje, Sweden), and short-term effects (after 3 days) were compared with those induced by castration. Castration caused decreased vascular density in the normal tissue surrounding the tumor and consequently increased tumor hypoxia and apoptosis, and moderately decreased tumor growth. ZD6474 treatment resulted in decreased tumor vascular density accompanied by increased tumor hypoxia, apoptosis, and decreased tumor growth, suggesting that castration and antiangiogenic therapy work through similar mechanisms. Interestingly, castration or ZD6474 alone worked by reducing vascular density in the surrounding normal tissue and ZD6474 also in the tumor. Combined treatment with castration + ZD6474 was more effective than castration and ZD6474 alone in inducing tumor hypoxia, apoptosis, necrosis, and decreasing tumor vascular density. These findings show that a drug that targets the vasculature in the tumor and in the surrounding ventral prostate lobe could mimic and even enhance the effects of castration. Our present findings thus suggest that castration + ZD6474 could be a particularly effective way to treat prostate tumors.

Benzopyrans Are Selective Estrogen Receptor β Agonists with Novel Activity in Models of Benign Prostatic Hyperplasia

Benzopyran selective estrogen receptor beta agonist-1 (SERBA-1) shows potent, selective binding and agonist function in estrogen receptor beta (ERbeta) in vitro assays. X-ray crystal structures of SERBA-1 in ERalpha and beta help explain observed beta-selectivity of this ligand. SERBA-1 in vivo demonstrates involution of the ventral prostate in CD-1 mice (ERbeta effect), while having no effect on gonadal hormone levels (ERalpha effect) at 10x the efficacious dose, consistent with in vitro properties of this molecule.