Role of peptide growth factors in the prostate: a review

Longitudinal changes in prostate volume in a community-based cohort study of middle-aged and elderly men in rural China

BACKGROUND

Prostate volume (PV) and its change rate are important for the progression of prostate disease, but studies on their estimates are inconsistent.

OBJECTIVES

To investigate whether age, prostate-specific antigen (PSA), and other specific characteristics are associated with PV and its change rate.

MATERIALS AND METHODS

A community-based cohort study was conducted in a rural area of China among male residents aged 40-80 years. PV was estimated at baseline and at 4 years of follow-up by trans-abdominal ultrasound. Annual PV change rate (PVCR) was calculated as change in volume divided by time interval. Baseline characteristics, including age, serum PSA, and hormones, were evaluated. And their relationships with PV or PVCR were assessed with Pearson correlation and multivariate linear regression analyses.

RESULTS

Totally, 462 participants completed the follow-up with baseline PV (PV₀ ) of 15.6 ± 5.5 ml. PV₀ was highly correlated with age and PSA in pairwise correlations (Pearson r = 0.35 and 0.34, respectively, p < 0.01). Multivariate linear regression showed similar associations that PV₀ tended to increase with age and PSA. The average PVCR was 0.7 ± 1.8 ml/year. In pairwise correlations, PVCR was inversely correlated with PV₀ and positively correlated with PSA, while it was not significantly related to baseline age. Linear regression of PVCR on age and PSA in groups classified by PV₀ quartile showed that age was not a significant estimator of PVCR, whereas PSA was. In each PV₀ group, PVCR tended to increase with PSA.

DISCUSSION AND CONCLUSION

PV was positively associated with age and PSA, and it tended to grow faster in men with smaller baseline PV and higher PSA. PSA can be a valuable parameter for estimating both the size and the growth speed of prostate. Although age is associated with prostate enlargement, it does not appear to be related to the longitudinal change rate of PV.

Her-2/Neu Receptor in Prostate Cancer Development and Progression to Androgen Independence

Development of prostate cancer and progression to androgen-independent disease is correlated with increased expression of growth factors and receptors capable of establishing autocrine and/or paracrine growth-stimulatory loops. A thorough review was made of the current literature and recent abstract presentations at scientific meetings focusing on the role of the HER-2/neu (c-erbB2) receptor in prostate cancer and the potential clinical usefulness of its specific inhibitors. In the past 10 years, conflicting results on HER-2/neu expression in prostate cancer have been reported. More recently, four studies have shown experimental evidence of HER-2/neu in the development of prostate cancer and, more specifically, in the progression to a hormone-refractory clinical behavior. Furthermore, it has been proposed that HER-2 family and androgen receptors function synergistically in the absence of androgen, which suggests a crosstalk between the HER-2/neu and androgen receptor pathways. Finally, clinical trials are in progress in prostate cancer patients to test novel agents that selectively interfere with HER-2/neu activity.

Transforming Growth Factor β1 Stimulates Urokinase Plasminogen Activator System on Prostate Cancer Cells

The effect of TGFβ1 on the proliferation and plasminogen activator system (PA) of two prostate carcinoma cell lines, PC3 and DU145, was investigated. PA, particularly urokinase plasminogen activator (uPA), has been implicated in extracellular proteolysis, local invasiveness, metastatic spread and angiogenesis. High levels of uPA and plasminogen activator inhibitor-1 (PAI-1) correlate with poor prognosis in several cancers. TGFβ1 had no significant effect on the proliferation of either cell line. TGFβ1 increased the production of uPA in PC3 and DU145 cells. Despite the very low PAI-1 protein levels in both cell lines, TGFβ1 treatment resulted in a remarkable increase in PAI-1 secretion. PAI-2 protein was also increased by 59% in the PC3 cells. A divergent effect of TGFβ1 on the uPA enzyme activity was observed (28% decrease in PC3 and 131% increase in DU145 cells). Overall, TGFβ1 treatment did not affect the invasion of reconstituted basement membrane of PC3 cells. In addition to the uPA:PAI-1 ratio, the presence of PAI-2 may be an important factor in the determination of metastatic sites for prostate cancer cells. In conclusion, the potential contribution of TGFβ1 to tumor invasion may be considered as positive, based on both loss of growth inhibition and stimulation of components of the invasive system of prostate carcinoma.

Design and Synthesis of Analogues of Marine Natural Product Galaxamide, an N-methylated Cyclic Pentapeptide, as Potential Anti-Tumor Agent in Vitro

Herein, we report design and synthesis of novel 26 galaxamide analogues with N-methylated cyclo-pentapeptide, and their in vitro anti-tumor activity towards the panel of human tumor cell line, such as, A549, A549/DPP, HepG2 and SMMC-7721 using MTT assay. We have also investigated the effect of galaxamide and its representative analogues on growth, cell-cycle phases, and induction of apoptosis in SMMC-7721 cells in vitro. Reckon with the significance of conformational space and N-Me aminoacid (aa) comprising this compound template, we designed the analogues with modification in N-Me-aa position, change in aa configuration from l to d aa and substitute one Leu-aa to d/l Phe-aa residue with respective to the parent structure. The efficient solid phase parallel synthesis approach is employed for the linear pentapeptide residue containing N-Me aa, followed by solution phase macrocyclisation to afford target cyclo pentapeptide compounds. In the present study, all galaxamide analogues exhibited growth inhibition in A549, A549/DPP, SMMC-7721 and HepG2 cell lines. Compounds 6, 18, and 22 exhibited interesting activities towards all cell line tested, while Compounds 1, 4, 15, and 22 showed strong activity towards SMMC-7221 cell line in the range of 1–2 μg/mL IC₅₀. Flow cytometry experiment revealed that galaxamide analogues namely Compounds 6, 18, and 22 induced concentration dependent SMMC-7721 cell apoptosis after 48 h. These compounds induced G0/G1 phase cell-cycle arrest and morphological changes indicating induction of apoptosis. Thus, findings of our study suggest that the galaxamide and its analogues 6, 18 and 22 exerted growth inhibitory effect on SMMC-7721 cells by arresting the cell cycle in the G0/G1 phase and inducing apoptosis. Compound 1 showed promising anti-tumor activity towards SMMC-7721 cancer cell line, which is 9 and 10 fold higher than galaxamide and reference DPP (cisplatin), respectively.

Linking pre-diabetes with benign prostate hyperplasia. IGFBP-3: a conductor of benign prostate hyperplasia development orchestra?

Benign prostatic hyperplasia (BPH) represents a pattern of non-malignant growth of prostatic fibromuscular stroma. Metabolic disturbances such us pre-diabetes and metabolic syndrome may have a role in BPH pathophysiology. A potential explanation for the above relationship involves the insulin-like growth factor (IGF) axis as well as IGF binding proteins, (IGFBPs) of which the most abundant form is IGFBP-3. Therefore, the aim of the present study was to investigate the association between intra-prostatic levels of IGF-1, IGF-2 as well as to evaluate the role of locally expressed IGFBP-3 in BPH development in pre-diabetes. A total of 49 patients admitted to the Urology department of a tertiary urban Greek hospital, for transurethral prostate resection, or prostatectomy and with pre-diabetes [impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) or both] were finally included. The majority of the sample consisted of subjects with IGT (51.0%), followed by IFG and IGT (32.7%) and isolated IFG (16.3%). For all participants a clinical examination was performed and blood samples were collected. In addition, total prostate (TP) volume or transitional zone (TZ) volume were estimated by transrectal ultrasonography. The results of the multivariate analysis regarding TP volume showed that higher PSA (p<0.001), larger waist circumference (p=0.007) and higher IGFBP-3 expression levels (p<0.001) independently predicted higher TP volume. The results regarding the volume of the TZ showed that higher PSA (p<0.001), larger waist circumference (p<0.001) and higher IGFBP-3 expression levels (p=0.024) were independently associated with higher TZ volume. Our findings show that intra-prostatic levels of IGFBP-3, PSA and waist circumference, but not overall obesity, are positively associated with prostate volume. IGFBP-3 seems to be a multifunctional protein, which can potentiate or inhibit IGF activity.

Involvement of fibroblast growth factor receptor genes in benign prostate hyperplasia in a Korean population

Fibroblast growth factors (FGFs) and their receptors (FGFRs) have been implicated in prostate growth and are overexpressed in benign prostatic hyperplasia (BPH). In this study, we investigated whether single nucleotide polymorphisms (SNPs) of the FGFR genes (FGFR1 and FGFR2) were associated with BPH and its clinical phenotypes in a population of Korean men. We genotyped four SNPs in the exons of FGFR1 and FGFR2 (rs13317 in FGFR1; rs755793, rs1047100, and rs3135831 in FGFR2) using direct sequencing in 218 BPH patients and 213 control subjects. No SNPs of FGFR1 or FGFR2 genes were associated with BPH. However, analysis according to clinical phenotypes showed that rs1047100 of FGFR2 was associated with prostate volume in BPH in the dominant model (GA/AA versus GG, P = 0.010). In addition, a significant association was observed between rs13317 of FGFR1 and international prostate symptom score (IPSS) in the additive (TC versus CC versus TT, P = 0.0022) and dominant models (TC/CC versus TT, P = 0.005). Allele frequency analysis also showed significant association between rs13317 and IPSS (P = 0.005). These results suggested that FGFR genes could be related to progression of BPH.

Vascular endothelial growth factor (VEGF) expression in locally advanced prostate cancer: secondary analysis of radiation therapy oncology group (RTOG) 8610

Background

Angiogenesis is a key element in solid-tumor growth, invasion, and metastasis. VEGF is among the most potent angiogenic factor thus far detected. The aim of the present study is to explore the potential of VEGF (also known as VEGF-A) as a prognostic and predictive biomarker among men with locally advanced prostate cancer.

Methods

The analysis was performed using patients enrolled on RTOG 8610, a phase III randomized control trial of radiation therapy alone (Arm 1) versus short-term neoadjuvant and concurrent androgen deprivation and radiation therapy (Arm 2) in men with locally advanced prostate carcinoma. Tissue samples were obtained from the RTOG tissue repository. Hematoxylin and eosin slides were reviewed, and paraffin blocks were immunohistochemically stained for VEGF expression and graded by Intensity score (0–3). Cox or Fine and Gray’s proportional hazards models were used.

Results

Sufficient pathologic material was available from 103 (23%) of the 456 analyzable patients enrolled in the RTOG 8610 study. There were no statistically significant differences in the pre-treatment characteristics between the patient groups with and without VEGF intensity data. Median follow-up for all surviving patients with VEGF intensity data is 12.2 years. Univariate and multivariate analyses demonstrated no statistically significant correlation between the intensity of VEGF expression and overall survival, distant metastasis, local progression, disease-free survival, or biochemical failure. VEGF expression was also not statistically significantly associated with any of the endpoints when analyzed by treatment arm.

Conclusions

This study revealed no statistically significant prognostic or predictive value of VEGF expression for locally advanced prostate cancer. This analysis is among one of the largest sample bases with long-term follow-up in a well-characterized patient population. There is an urgent need to establish multidisciplinary initiatives for coordinating further research in the area of human prostate cancer biomarkers.

The molecular biology of prostate cancer morbidity and mortality: Accelerated death from ejaculate poisoning?

The molecular biology of host-tumor interactions unique to human prostate cancer that cause patient morbidity are poorly understood despite the prevalence of this neoplasm. Little is known fundamentally about prostate-specific exocrine gene products secreted by metastatic prostate carcinoma cells at metastatic sites that cause diffuse bone pain, immunosuppression, anemia, cachexia, and other clinical signs of advanced prostate cancer. Growing evidence supports the presence of androgen-regulated exocrine gene products as independent mediators of prostate cancer morbidity. The experimental and clinical implications of a hypothesis that prostate-specific exocrine genes cause patient morbidity are discussed.

MicroRNA-1 inhibits proliferation of hepatocarcinoma cells by targeting endothelin-1

AIMS

MicroRNA-1 (miR-1) has been demonstrated as a tumor-suppressive miRNA, which shows a down-regulated pattern in several human malignancies including hepatocellular carcinoma (HCC). However, the pathophysiologic roles of miR-1 and their mechanisms in HCC tumorigenesis are still not totally elucidated.

MAIN METHODS

Pre-miR-1 was cloned into pSuper plasmid to overexpress the miR-1 in hepatoma cells. Real-time PCR and Western blot were applied to detect miR-1, ET-1 mRNA and protein levels respectively. Dual luciferase reporter assay was conducted to investigate the binding site of miR-1 on 3'UTR of ET-1 mRNA. Proliferation of hepatoma cells was evaluated by MTT assay.

KEY FINDINGS

We observed that over-expression of miR-1 by miRNA-expressing plasmid transfection in HepG2 and Hep3B cells significantly reduced the proliferation of these cells. To explore the mechanism, we examined the potential target genes of miR-1 by bioinformatics. A potent mitogen, Endothelin-1 (ET-1), attracted our attention. Elevated expression of ET-1 but reduced miR-1 level was detected both in human liver cancer tissues and in hepatoma cell lines using Western Blot and miRNA real-time PCR respectively. By the over-expression and inhibition of miR-1 in HepG2 and Hep3B, we confirmed that miR-1 negatively regulated ET-1 expression in hepatoma cells. A luciferase reporter assay showed that miR-1 regulation was established by pairing to a complementary binding site within the ET-1 3'UTR. Finally, attenuated proliferation of hepatoma cells by over-expression of miR-1 could be partially restored by exogenous ET-1 treatment.

SIGNIFICANCE

Our findings demonstrate that miR-1 could inhibit ET-1 expression to attenuate the proliferation of hepatoma cells.

Neuropeptide-inducible upregulation of proteasome activity precedes nuclear factor kappa B activation in androgen-independent prostate cancer cells

BACKGROUND

Upregulation of nuclear factor kappa B (NFκB) activity and neuroendocrine differentiation are two mechanisms known to be involved in prostate cancer (PC) progression to castration resistance. We have observed that major components of these pathways, including NFκB, proteasome, neutral endopeptidase (NEP) and endothelin 1 (ET-1), exhibit an inverse and mirror image pattern in androgen-dependent (AD) and -independent (AI) states in vitro.

METHODS

We have now investigated for evidence of a direct mechanistic connection between these pathways with the use of immunocytochemistry (ICC), western blot analysis, electrophoretic mobility shift assay (EMSA) and proteasome activity assessment.

RESULTS

Neuropeptide (NP) stimulation induced nuclear translocation of NFκB in a dose-dependent manner in AI cells, also evident as reduced total inhibitor κB (IκB) levels and increased DNA binding in EMSA. These effects were preceded by increased 20 S proteasome activity at lower doses and at earlier times and were at least partially reversed under conditions of NP deprivation induced by specific NP receptor inhibitors, as well as NFκB, IκB kinase (IKK) and proteasome inhibitors. AD cells showed no appreciable nuclear translocation upon NP stimulation, with less intense DNA binding signal on EMSA.

CONCLUSIONS

Our results support evidence for a direct mechanistic connection between the NPs and NFκB/proteasome signaling pathways, with a distinct NP-induced profile in the more aggressive AI cancer state.

Effect of dexamethasone and testosterone treatment on the regulation of insulin-degrading enzyme and cellular changes in ventral rat prostate after castration

Insulin-degrading enzyme (IDE) has been shown to enhance the binding of androgen and glucocorticoid receptors to DNA in the nuclear compartment. Glucocorticoids cause hyperglycaemia, peripheral resistance to insulin and compensatory hyperinsulinaemia. The aim of the present study was to investigate the effect of dexamethasone (D), testosterone (T) and dexamethasone plus testosterone (D + T) on the regulation of IDE and on the remodelling of rat ventral prostate after castration (C). Castration led to a marked reduction in prostate weight (PW). Body weight was significantly decreased in the castrated animals treated with dexamethasone, and the relative PW was 2.6-fold (±0.2) higher in the D group, 2.8-fold (±0.3) higher in the T group and 6.6-fold (±0.6) higher in the D + T group in comparison with the castrated rats. Ultrastructural alterations in the ventral prostate in response to androgen deprivation were restored after testosterone and dexamethasone plus testosterone treatments and partially restored with dexamethasone alone. The nuclear IDE protein level indicated a 4.3-fold (±0.4) increase in castrated rats treated with D + T when compared with castration alone. Whole-cell IDE protein levels increased approximately 1.5-fold (±0.1), 1.5-fold (±0.1) and 2.9-fold (±0.2) in the D, T and D + T groups, respectively, when compared with castration alone. In conclusion, the present study reports that dexamethasone-induced hyperinsulinaemic condition plus exogenous testosterone treatment leads to synergistic effects of insulin and testosterone in the prostatic growth and in the amount of IDE in the nucleus and whole epithelial cell.

Effects of mepartricin, a polyene macrolide antibiotic, on estrogen-induced hyperplastic growth of the dorsolateral prostate and seminal vesicle in immature castrated rats

OBJECTIVE

To investigate the effects of mepartricin, a polyene macrolide antibiotic, on estrogen-induced hyperplastic prostate and seminal vesicle (SV) growth in castrated rats.

MATERIAL AND METHODS

Immature rats aged 3 weeks were castrated and left untreated for 1 week. Then, 17beta-estradiol benzoate (E(2)-BA) was subcutaneously injected at a dose of 10 microg/day twice weekly, and mepartricin was orally administered at doses of 2.5, 5 and 10 mg/kg once daily for 3 weeks. The weights and hydroxyproline contents of the prostate and SV, the activity of growth factors (GFs) in the dorsolateral prostate (DLP) and the serum estrogen level were measured. Histological examination of the prostate and SV was also performed.

RESULTS

Mepartricin dose-dependently suppressed the increase in the serum estrogen level, the weights and hydroxyproline contents of the DLP and SV and the elevation of GF activity in the DLP induced by E(2)-BA treatment. Histological examination also revealed that treatment with mepartricin reduced collagen accumulation and thickening of the smooth muscle layer in the DLP and SV, and proliferation of the glandular epithelium in the DLP.

CONCLUSIONS

These results suggest that mepartricin suppresses hyperplastic growth of the DLP and SV induced by estrogen in immature castrated rats, the underlying mechanism being a reduction in the serum estrogen level, thereby suppressing stromal cell proliferation and activation.

Variability in Weight and Histological Appearance of the Prostate of Beagle Dogs Used in Toxicology Studies

This review was performed to assess variations in weight and histologic appearance of the prostate of untreated male beagle dogs between 23 and 108 weeks of age, from two breeding centers. Data from 125 control beagle dogs from twenty-seven regulatory toxicology studies were used. Age, terminal body weight, and prostate weight were analyzed. Prostate sections were examined microscopically, and histological changes—such as development of acini, amount of secretion, and patterns of dilation and inflammation—were recorded and graded when appropriate. The influence of age, terminal body weight, and source on the weight and histological appearance of the prostate, and the degree of interanimal variation were evaluated

Stat3 promotes metastatic progression of prostate cancer

There are currently no effective therapies for metastatic prostate cancer because the molecular mechanisms that underlie the metastatic spread of primary prostate cancer are unclear. Transcription factor Stat3 is constitutively active in malignant prostate epithelium, and its activation is associated with high histological grade and advanced cancer stage. In this work, we hypothesized that Stat3 stimulates metastatic progression of prostate cancer. We show that Stat3 is active in 77% of lymph node and 67% of bone metastases of clinical human prostate cancers. Importantly, adenoviral gene delivery of wild-type Stat3 (AdWTStat3) to DU145 human prostate cancer cells increased the number of lung metastases by 33-fold in an experimental metastasis assay compared with controls. Using various methods to inhibit Stat3, we demonstrated that Stat3 promotes human prostate cancer cell migration. Stat3 induced the formation of lamellipodia in both DU145 and PC-3 cells, further supporting the concept that Stat3 promotes a migratory phenotype of human prostate cancer cells. Moreover, Stat3 caused the rearrangement of cytoplasmic actin stress fibers and microtubules in both DU145 and PC-3 cells. Finally, inhibition of the Jak2 tyrosine kinase decreased both activation of Stat3 and prostate cancer cell motility. Collectively, these data indicate that transcription factor Stat3 is involved in metastatic behavior of human prostate cancer cells and may provide a therapeutic target to prevent metastatic spread of primary prostate cancer.

[Benign prostatic hyperplasia: a highly prevalent disease in the elderly]

The present review aims to provide an overview of benign prostatic hyperplasia (BPH), which has a remarkably high prevalence. The various theories of the aetiology of the disease are discussed, with special emphasis on those that concern the influence of growth factors. Questions related to the physiopathology of BPH are briefly summarized, since many symptoms apparently related to the disease may be caused by ageing or by interacting factors other than prostatism. The most common clinical manifestations, with symptoms divided into irritative and obstructive, as well as the currently available diagnostic procedures, are described. Finally, the therapeutic options are discussed, with special reference to KTP and Holmiun laser, which will drastically change treatment in the future.

Testosterone effect on immature prostate gland development associated with suppression of transforming growth factor-β

The aim of this study was to evaluate the effect of testosterone treatment on the pattern of prostate cell proliferation and differentiation and their correlation with the expression of transforming growth factor-beta (TGF-beta). Prostate gland development was compared in intact immature dogs with one-month testosterone-treated immature dogs. Testosterone treatment resulted in a tenfold increase in prostate gland weight compared to untreated dogs, with a typical organization of the gland into a structure similar to that observed in mature dogs. The narrow acini which contain flat basal cells in immature glands were transformed into tubuloacinar structures containing columnar secretory cells and basal cells. The stromal compartments showed an increase in the muscular component as evidenced by the high reactivity to alpha-actin with no remarkable changes in the vimentin expression. In addition, testosterone treatment induced a significant reduction in the proliferation capacity of stromal cells but with no noticeable changes in the proliferation pattern of epithelial cells. These changes in the prostate are associated with a twofold decrease in TGF-beta mRNA expression as assessed by Real-Time PCR. However, the immunolocalization of TGF-beta was shifted slightly from the epithelial cells in untreated animals to the stromal cells of treated animals. Based on these results it appears that testosterone acts to coordinate prostatic cell proliferation and differentiation and direct their organization into a structure resembling that of the mature gland. The testosterone regulation of the prostate gland appears to involve the regulation of TGF-beta gene expression.

Oxytocin and the human prostate in health and disease

Oxytocin is a peptide hormone produced by the neurohypophysis. The discovery that the peptide is produced locally within the male and female reproductive tracts has raised the possibility that oxytocin may have paracrine and autocrine actions outside of the nervous system. Oxytocin and its receptor have been identified in the human prostate. The prostate is an androgen-dependent organ whose function is to secrete components of the seminal fluid. Oxytocin has been shown to modulate contractility of prostate tissue and also to regulate local concentrations of the biologically active androgens. Oxytocin has also been shown to regulate cell growth. Prostate disease is common and results from abnormal growth of the gland. Oxytocin concentrations are altered in both benign and malignant prostate diseases and in vitro studies suggest that the peptide may be involved in the pathophysiology of these diseases.

Tumour plasticity and extravascular circulation in ECV304 human bladder carcinoma cells

BACKGROUND

The concepts of vasculogenic mimicry and mosaic vessels have been proposed as novel modes of tumour neovascularisation. However, the presence and significance of these types of neovascularisation remain unclear.

MATERIALS AND METHODS

ECV304 human bladder carcinoma cells were used to determine how tumour cells take part in tumour neovascularisation.

RESULTS

Subcutaneous ECV304 xenografts in mice showed various vessel types, including angiogenic vessels, tumour cell-related vessels and extracellular matrix networks. A tracer experiment demonstrated perfusion of beads in these structures. ECV304 cells, cultured on collagen I gels, formed tube networks with expressions of several endothelial-related markers. In coculture models of ECV304 cells and human umbilical vein endothelial cells, the two cells collaborated to form sprouts or networks.

CONCLUSION

ECV304 cells possess an endothelial character which confers the ability to mimic and collaborate with vascular endothelial cells and facilitates the acquisition of tumour microcirculation.

Castration induced changes in dog prostate gland associated with diminished activin and activin receptor expression

This study was conducted to evaluate the effect of androgen ablation on dog prostate gland structure and the proliferation capacity of the prostatic cells and their association with the expression of Activin A and Activin RIIA receptor. The effect of androgen on the prostate gland was compared in intact and castrated dogs after one and two weeks. Specific primary antibodies were used to immunolocalize activin-A, activin receptor type II A and the proliferation marker (PCNA). The results showed that the glandular acini of the prostate gland of intact dogs are lined by tall columnar secretory cells and less abundant flattened basal cells and surrounded by a thin fibromuscular tissue. The cytoplasm of the glandular cells exhibited an intense immunoreaction for activin A and activin RIIA receptor while basal cells expressed PCNA. Castration induced a remarkable atrophy of the prostatic acini associated with a progressive loss of secretory epithelial cells, which showed a dramatic decrease to complete disappearance of Activin A and Activin RIIA receptor immunoreactions. The remaining cells of the atrophied acini continue to express PCNA and the inter-acinar fibromuscular tissue showed a remarkable increase in its mass and are induced to express PCNA. These results indicated that androgen is required for the survival of epithelial cells and to maintain growth-quiescent fibromuscular cells, while basal cell proliferation is androgen independent. The changes in the Activin A and Activin RIIA receptor localization and their association with the dynamic pattern of prostate gland regression after castration suggested that Activin A and Activin RIIA receptor expression are androgen dependent.

Can we prevent prostate cancer? Rationale and current status of prostate cancer chemoprevention

Prostate cancer has been one of the most frequent cancers among men in Western countries for the past decade. Investigation of prostate cancer prevention is very attractive, because prostate cancer has a high incidence, long-term natural history, regional difference in incidence, and is effected by sex steroids. Chemoprevention is defined as the use of specific agents to suppress or reverse carcinogenesis and to prevent the development of cancer. The development of chemoprevention strategies against prostate cancer would be of medical and economic importance. Basic and clinical research of chemoprevention of prostate cancer are under active investigation. This article aims to summarize and review the basic evidence and clinical trials on prostate cancer chemoprevention. Recent research has demonstrated that many agents, such as agents altering sex steroid signaling, drugs inducing antiproliferation/differentiation, retinoids, anti-inflammatory drugs, and antioxidants, could be potential preventatives for prostate cancer. Large-scale clinical trials have suggested that 5alpha-reductase inhibitor finasteride, selenium, and vitamin E can function as a chemopreventive agent. Although no definitely effective strategies of prostate cancer prevention have been identified yet, increasing evidence will provide effective and safe strategies that bring clinical benefits.

Androgen- and estrogen-dependent regulation of insulin-degrading enzyme in subcellular fractions of rat prostate and uterus

Innumerous data support the fact that insulin-degrading enzyme (IDE) is the primary enzymatic mechanism for initiating and controlling cellular insulin degradation. Nevertheless, insulin degradation is unlikely to be the only cellular function of IDE, because it appears that some cellular effects of insulin are mediated by IDE as a regulatory protein. Insulin-degrading enzyme shows a significant correlation with various cellular functions, such as cellular growth and differentiation, and the expression of IDE is developmentally regulated. Besides insulin, other substrates are also degraded by IDE, including various growth-promoting peptides. It has also been shown that IDE enhances the binding of androgen to DNA in the nuclear compartment. It is also known that the androgen hormones have a stimulatory effect on prostate growth, and that estradiol stimulates uterine growth. To establish whether IDE is regulated by a cellular prostate/uterine growth stimulus, the present study assessed whether IDE was modified in quantity and activity during proliferative conditions (castration + testosterone in the male rat, or castration + estradiol or the proestrus phase of the estrous cycle in the female rat) and autolysis (castration or the metestrus phase of the estrous cycle) using cytosolic and nuclear fractions of rat prostate and cytosolic fractions of rat uterus. The activity and amount of IDE decreased in the cytosolic fraction with castration and during metestrus, and increased with testosterone or estradiol treatment and during proestrus. In the nuclear fraction, the quantity of the IDE followed the same pattern observed in the cytosolic fraction, although without degradative activity. The data presented here suggest that IDE may participate in prostatic and uterine growth and that the testosterone or estradiol and/or prostate and uterus insulin-like growth factors may be important factors for the expression and regulation of IDE in the prostate and uterus.

Trypsin stimulates the phosphorylation of p42,44 mitogen-activated protein kinases via the proteinase-activated receptor-2 and protein kinase C epsilon in human cultured prostate stromal cells

BACKGROUND

The pathogenesis of benign prostatic hyperplasia (BPH) is not well understood. It involves the proliferation of prostate stromal cells. The proteinase-activated receptor subtype 2 (PAR-2) receptor is expressed by human prostate tissue and can be stimulated by serine proteases. Prostate epithelial cells secrete serine proteases such as trypsin, prostate specific antigen (PSA), and human glandular kallikrein (hK2). The p42,44 mitogen activated protein kinase (MAP kinase) pathway regulates cell proliferation. Trypsin can stimulate this pathway via the PAR-2 receptor and protein kinase C (PKC) in other tissues. Serine proteases secreted by prostate epithelial cells may interact with PAR-2 receptors expressed by prostate stromal cells causing them to proliferate. The aim of the present study was to establish whether functional PAR-2 receptors are expressed by human prostate stromal cells (HPSCs) and to determine whether PAR-2 stimulation can activate p42,44 MAP kinase via a pathway involving PKC.

METHODS

HPSCs were cultured from patients undergoing trans urethral resection of the prostate (TURP). HPSCs were stimulated with PAR agonists. Immunoblotting of HPSC lysate with anti-p42,44 MAP kinase and -PKC isoforms. Data were analyzed with densitometry.

RESULTS

Trypsin and the PAR-2 synthetic peptide SLIGKV caused significant increases in MAP kinase phosphorylation and calcium mobilization in HPSCs. The MAP kinase response was attenuated by pertussis toxin (PTX), phorbol 12,13 dibutyrate, Go6983, and Ro 318220. The PKC isoforms alpha, delta, epsilon, and zeta were detected in HPSCs. Trypsin caused the translocation of PKC(epsilon) from the cytosol to the membrane in HPSCs and was able to stimulate cellular proliferation.

CONCLUSIONS

The PAR-2 selective serine protease trypsin activates p42,44 MAP kinase phosphorylation via PKC(epsilon). This may be an important mechanism of BPH pathophysiology.

Expression of biomarkers modulating prostate cancer progression: implications in the treatment of the disease

OBJECTIVES

To determine whether COX-2, bcl-2 and neoangiogenesis are related to human prostate cancer relapse after definitive surgical treatment and progression toward androgen independence and to evaluate the association between the patterns of these tumoral biomarkers and other standard clinico-pathological parameters (such as Gleason score, PSA, TNM stage).

MATERIALS AND METHODS

We retrospectively analyzed the records on 126 prostate cancer samples from patients treated at our University Hospital from 1995 to 2002. The 72 patients with clinically localized disease (group 1) had undergone radical prostatectomy. Another 54 patients (group 2) had metastatic androgen-independent disease. Archived material relating to the subjects was then immunostained for bcl-2, COX-2 and CD-31, using an anti-bcl-2 monoclonal primary antibody, an anti-COX-2 polyclonal rabbit antibody and an anti-CD-31 monoclonal mouse antibody to evaluate neoangiogenesis (MVD, microvessel density).

RESULTS

We found that bcl-2, COX-2 and MVD expression increased from group 1 to group 2. The intergroup difference was significant only for high MVD (P < 0.05). On the other hand, high MVD, high bcl-2 and high COX-2 expression was correlated with a higher PSA level (P < 0.01), whereas only a high MVD was also related with Gleason score (P < 0.05). We used univariate analysis to evaluate the prognostic impact of biologic and clinico-pathologic parameters on the disease-free-survival of 72 patients treated by radical prostatectomy. A total of 30 patients (41.6%) experienced biochemical relapse; bcl-2, COX-2 and MVD significantly correlated with disease relapse in these patients. In fact, we observed disease relapse in 24/45 (53%) with high bcl-2 expression, in 15/21 (71%) with a high MVD count and finally, in 30/58 (52%) with high COX-2 expression. Finally, PSA value and Gleason score were the only two biologic markers significantly associated to disease relapse in a multivariate analysis.

CONCLUSIONS

Our results strongly support a role for bcl-2, COX-2 and angiogenesis in the development and progression of prostate cancer. Of course, we are aware of the small sample size considered in our study. Further investigations would better clarify the prognostic and therapeutic implications of these findings.

Antiandrogen-like actions of an antioxidant on survivin, Bcl-2 and PSA in human prostate cancer cells

BACKGROUND

Androgens, while essential for prostate gland development, have been postulated to contribute to carcinogenesis, and antioxidants have been postulated to suppress prostate cancer development. We theorized that antioxidants might suppress prostate cancer cell growth by blocking androgen effects on cell survival. This hypothesis was tested by in vitro studies conducted in ALVA-101, an androgen responsive human prostate cancer cell line.

METHODS

ALVA-101 was cultured with or without testosterone (T, 10(-12) M) and pyrrolidinedithiocarbamate (PDTC, 10 microg/mL). Cell Titer 96 AQ, electrophoretic mobility shift assay (EMSA), reverse transcription-polymerase chain reaction (RT-PCR), Northern and Western blot were used to quantify the cell growth, nuclear factor-kappa B (NF-kappaB) activity, mRNAs of survivin, Bcl-2, androgen receptor (AR) and prostate specific antigen (PSA), and proteins of AR and survivin.

RESULTS

PDTC suppressed EMSA of NF-kappaB and significantly decreased (p < 0.05) T's stimulatory effects on cell growth, mRNAs of survivin, Bcl-2, AR and PSA and synthesis of proteins of AR and survivin. Antisense to both survivin and Bcl-2 suppressed cell growth.

CONCLUSIONS

PDTC, a potent inducer of apoptosis, exerts antiandrogen-like action by reducing AR protein and reversing the stimulatory effects of androgen on potent inhibitors of apoptosis.

Urinary Basic Fibroblast Growth Factor in Bladder Cancer Patients

INTRODUCTION

Angiogenesis plays a significant role in the growth and progress of cancer, thus we evaluated the levels of urinary basic fibroblast growth factor (bFGF) in bladder cancer (Ca) patients and investigated any possible correlation between this angiogenic factor with tumor stage and grade.

MATERIALS AND METHODS

Urine samples from 41 patients with bladder Ca, 11 patients with history of bladder Ca but negative follow-up cystoscopy, 18 patients with benign prostate hyperplasia (BPH) and 15 normal healthy volunteers were assayed using an enzyme-linked immunosorbent assay for bFGF. Resulting values were normalized against urine creatinine and expressed as pg/g.

RESULTS

The median urinary bFGF level of patients with active disease, history of bladder carcinoma and negative follow-up cystoscopy, BPH, and healthy volunteers were 2,717, 1,009, 1,414 and 1,100 pg/g, respectively. There was a statistically significant difference between median bFGF levels of patients with active bladder Ca and those of the other groups (p = 0.000). Eleven patients with invasive bladder Ca had a median bFGF value of 6,880 pg/g that was significantly increased (p = 0.002) compared to the median of 2,312 pg/g of those with superficial tumors (Ta 14, T1 16). Grades 1, 2 and 3 carcinoma were found in 5, 19 and 17 patients which had a median bFGF of 2,717, 1,762 and 3,617 pg/g, respectively, but the difference was not statistically significant (p = 0.13).

CONCLUSIONS

Our results confirm the implication of bFGF in the biology of bladder cancer, and demonstrate that urinary bFGF concentration seems to be significantly related to the stage but not to the grade of the disease supporting the proposed mechanisms of release of bFGF. Further studies are required in order to validate the potential clinical applications of bFGF for specific groups of bladder cancer patients.

Biologic feature of prostatic hyperplasia developed in spontaneously hypertensive rats

OBJECTIVES

To investigate alterations in cell kinetic and cellular composition in prostatic hyperplasia developed in spontaneously hypertensive (SH) rats from 15 to 54 weeks of age.

METHODS

Male SH rats (n = 20) and their normotensive counterparts, Wistar-Kyoto rats (n = 20), were studied. At 15, 29, 40, and 54 weeks of age, the ventral prostate was obtained to evaluate (a) cell proliferation by the proliferation index using proliferating cell nuclear antigen immunostaining and (b) apoptosis by the apoptotic index using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling assay. The percentage of area density of smooth muscle and fibroblastic tissues was determined with a computerized image analysis system after alpha-actin and vimentin immunostaining, respectively.

RESULTS

Compared with the data in the Wistar-Kyoto rats during the observation period, a significantly increased proliferation index in both epithelium and stroma (P <0.01) and a slightly increased apoptotic index in the epithelium without apoptotic cells in the stroma, with an imbalance in favor of cell proliferation, were noted in the prostatic hyperplasia of the SH rats. The value of the proliferation index was greatly increased in both the epithelium and the stroma of the SH rats between 15 and 29 weeks (P <0.05) but continued relatively steady from 29 to 54 weeks. A significantly increased percentage of smooth muscle area (P <0.01) and a much greater percentage of area density of smooth muscle than that of fibroblastic tissues (P <0.01) were observed in the prostatic hyperplasia of the SH rats.

CONCLUSIONS

The prostatic hyperplasia of SH rats may develop from both epithelial and stromal growth and could ultimately be promoted by an imbalance in favor of proliferative activity.

Genistein alters growth factor signaling in transgenic prostate model (TRAMP)

Genistein, a component of soy, has been reported to protect against spontaneously developing prostate tumors in the transgenic adenocarcinoma of mouse prostate (TRAMP) model. This is consistent with reports showing that Asians eating a diet high in soy have reduced incidence of clinically manifested prostate cancer. In order to understand the mechanism of action of genistein, we have investigated the expression of androgen and estrogen receptors, four growth factor receptors that signal via tyrosine protein kinases, and specific growth factor proteins in the dorsolateral prostates of TRAMP mice fed 250 mg genistein/kg diet, starting at 5 weeks of age. These analyses were carried out at 12 weeks, prior to the development of solid tumors, allowing us to readily investigate cell proliferation and biomarkers in premalignant tissue. Cell proliferation, AR, ER-alpha, EGFR, ErbB2, EGF, IGF-1R, IGF-1, VEGFR2, ERKs-1 and 2 proteins and TGF-alpha mRNA, but not ER-beta and VEGF, were significantly increased in prostates of TRAMP compared to C57BL/6 mice. Genistein in the diet significantly down-regulated cell proliferation, EGFR, IGF-1R, ERK-1 and ERK-2, but not AR, ER-alpha, ER-beta, ErbB2, EGF, TGF-alpha, IGF-1, VEGF and VEGFR in prostates of TRAMP mice. Serum testosterone and dihydrotestosterone concentrations were not significantly different in C57BL/6 or TRAMP male mice fed control or genistein-containing diets. The up-regulation of sex steroid receptors and multiple growth signaling pathways in TRAMP mice supports the concept of multiple dysregulation contributing to carcinogenesis. Down-regulation of the tyrosine kinase regulated proteins, EGFR and IGF-1R, and of the downstream mitogen-activated protein kinases, ERK-1 and 2, with genistein in the diet provides a possible mechanism for prostate cancer chemoprevention.

Relationship between upregulated oestrogen receptors and expression of growth factors in cultured, human, prostatic stromal cells exposed to estradiol or dihydrotestosterone

This study investigated the hypothesis that, in benign prostatic hyperplasia (BPH), upregulated oestrogen receptors (ER) and the action of androgens differentially regulate expression of stromal growth factors. Eight human prostatic stromal cell strains were subjected to a procedure to upregulate their ER by exposing them to 1 micromol 17beta-estradiol for 10 days followed by passage and growth in the absence of steroids. Four of the cell strains instead received 100 nmol dihydrotestosterone for 48 h. Immunoexpression of ERalpha, AR and six growth factors was quantified by flow cytometry in each case. Expression of ERalpha was significantly increased in six of eight cell strains. Expressions of six growth factors (FGF-2, FGF-7, IGF-1, TGF-beta1 NGF and e NOS) were elevated but only for FGF-7 was it significant. There was a significant positive correlation between the change in ERalpha and the change in FGF-2 and FGF-7, but not the other growth factors. Exposure to dihydrotestosterone reduced expression of ERalpha and all six growth factors, compared with oestrogen-treated cells but not significantly. It is concluded that upregulated ERalpha in prostatic stroma may have a greater modulating influence on synthesis of certain growth factors than the direct action of androgens and, by enhancing synthesis of FGF-2 and FGF-7, could play a significant role in the development of BPH.

Immunopathological prognostic and predictive factors in prostate cancer

Prostate cancer is the leading male malignancy in the Western world. Patients with prostate cancer have an unpredictable clinical course, as three biologically different types of tumor exist. This review summarises some of the recent progress made in understanding the biology of prostate cancer with special reference to the prognostic and predictive role of immunohistochemical markers. The prognostic value of established prognostic variables is also discussed.

Involvement of Growth Factor Receptors of the Epidermal Growth Factor Receptor Family in Prostate Cancer Development and Progression to Androgen Independence

The development of prostate cancer and the progression from a normal prostate epithelium to androgen-dependent cancer and eventually to hormone-refractory prostate cancer is a multistep process involving several changes in the function of different growth-regulatory signals. In the past 10 years, conflicting results on epidermal growth factor receptor (EGFR) family expression in prostate cancer have been reported. These differences may result from technical differences, lack of standardization of immunohistochemical assays, or different scoring methodologies. Recently, 4 studies have shown experimental evidence of a role of the EGFR family, particularly ErbB-2, in the development of prostate cancer and, more specifically, in the progression to hormone-refractory clinical behavior. These 4 studies were similar in some relevant aspects, such as the patient population. In fact, the patients in each study were divided into 3 groups that represent the progression of prostate cancer. In 3 of 4 studies, a statistically significant increase in ErbB-2 expression was detected by immunohistochemistry in the progression from hormone-dependent to hormone-independent disease. The expression of EGFR was also evaluated in 1 of the 4 studies. In a recent report from our group, a significant increase in EGFR expression was observed in patients treated with radical surgery, in patients who received hormonal therapy as primary therapy before radical prostatectomy, and, finally, in patients with metastatic and hormone-refractory disease. It has been proposed that EGFR family receptors and androgen receptors function synergistically in the absence of androgen suggesting cross-talk between the ErbB-2 and androgen receptor pathways, and that mitogen-activated protein kinase and phosphatidylinositol 3-kinase can be considered the transduction pathways. Finally, clinical trials are currently in progress in patients with prostate cancer testing novel agents that selectively interfere with these receptors, such as trastuzumab, an anti- ErbB-2 monoclonal antibody, and gefitinib (ZD1839, Iressa), a small-molecule selective EGFR tyrosine kinase inhibitor.

Antiestrogens and selective estrogen receptor modulators reduce prostate cancer risk

The development of chemoprevention strategies against prostate cancer would have the greatest overall impact both medically and economically against prostate cancer. Estrogens are required for prostate carcinogenesis. Estrogenic stimulation through estrogen receptor alpha in a milieu of decreasing androgens contributes significantly to the genesis of benign prostatic hyperplasia, prostate dysplasia, and prostate cancer. The ability of antiestrogens and selective estrogen receptor modulators (SERMs) to delay and to suppress prostate carcinogenesis is supported by preclinical, clinical, and epidemiological studies. SERMs have many features that make them attractive candidates for prostate cancer chemoprevention including their favorable safety profile and efficacy in preclinical prostate cancer models. The true clinical benefits of SERMs for chemoprevention to prevent prostate cancer, however, should continue to be investigated through human clinical trials. A phase IIb/III human clinical trial is currently evaluating safety and efficacy of toremifene, a SERM, in men who have high-grade prostatic intraepithelial neoplasia.

Upregulation of estrogen and androgen receptors modulate expression of FGF-2 and FGF-7 in human, cultured, prostatic stromal cells exposed to high concentrations of estradiol

This study was performed to develop an experimental model in which expression of estrogen receptors (ER) by human prostatic stromal cells could be reproducibly enhanced relative to similar cells with low ER expression. The second aim was to characterise changes in expression of ER, androgen receptor (AR), FGF-2 and FGF-7 in stromal cells exposed to high and low concentrations of estradiol and testosterone mimicking the different sex hormone levels between young and elderly men. Five strains of human prostatic stromal cells, isolated from BPH resections, were grown in steroid-free medium plus 1 micromol 17beta-estradiol. After 10 days, cells were passaged and grown in the same medium without estradiol until confluent. In a second study four cell strains were exposed to high and low concentrations of 17beta-estradiol and testosterone for 10 days. Cells were labelled with fluorescent antibodies to ERalpha, AR, FGF-2 and FGF-7 and the fluorescence intensity measured by flow cytometry. Following exposure to 1 micromol estradiol, stromal cells showed reduced expression of AR and ERalpha but after passage without estradiol they showed a 25% increase in both receptors over controls. Different combinations of sex hormones induced inconsistent changes with respect to expression of ER, AR and FGFs in the various cell-strains. However, there was a highly significant correlation between AR, ER and FGF-2 and FGF-7, which was cell strain-specific. Thus, changes in sex hormone balance per se may not be solely responsible for the observed increases in prostatic ER levels in BPH. Since expression of ER is correlated with synthesis of FGF-2 and FGF-7, it is likely that increases in stromal ER may mediate the synthesis of stromally-derived growth factors which contribute to the aetiopathogenesis of benign prostatic hyperplasia.

Increased expression of bone morphogenetic protein-7 in bone metastatic prostate cancer

BACKGROUND

Prostate cancer frequently metastasizes to bone. The skeletal metastases of prostate cancer origin are osteoblastic rather than osteolytic. Recently, the expression of bone morphogenetic proteins (BMPs) in prostate cancer cell lines was detected. The present study indicated the existence of BMP-7 in normal prostate tissue, but its function has not been clarified. The mechanism by which prostate cancer causes osteoblastic metastasis is not clear. We investigated the expression of BMP-7 and -6 in normal and metastatic bone tissues to clarify the biological relationship between the expression of BMPs and bone metastasis in prostatic cancer.

METHODS

Six samples of normal bone tissue and nine samples of bone metastasis tissue were collected during the autopsies of six patients with prostate cancer. Total RNA was extracted from these samples. After reverse transcription (RT) of the RNA samples, the expression of BMP-6 and -7 in each sample was measured by the real-time quantitative polymerase chain reaction (PCR). Glyceraldehyde phosphate dehydrogenase (GAPDH) was used as an internal standard.

RESULTS

Although the expression of BMP-7 was detected in five out of seven (71%) metastatic bone lesions of prostate cancer, it was not detected in normal bone tissues. The expression level of BMP-7 was significantly higher in metastatic bone lesions than in normal bone (P < 0.05). There was no significant difference between the level of expression of BMP-6 in metastatic bone lesions from prostate cancer and the level in normal bone tissue (P = 0.81).

CONCLUSIONS

These results suggest that high expression of BMP-7 in metastatic bone lesions of prostate cancer is related to osteoblastic metastasis. BMP-7 in the bone metastasis tissue indicates that the cells expressing BMP-7 probably originated from the prostate, because we have detected high expression of BMP-7 in the prostate. Prostate 54: 268-274, 2003.

Determination of percent area density of epithelial and stromal components in development of prostatic hyperplasia in spontaneously hypertensive rats

OBJECTIVES

To determine the percent area density of epithelial and stromal components in the development of prostatic hyperplasia in spontaneously hypertensive (SH) rats.

METHODS

The ventral lobes of prostates obtained from male SH rats and their normotensive counterparts, Wistar Kyoto (WKY) rats, were examined histopathologically at 15, 29, 40, and 54 weeks of age (5 SH and WKY rats each at each age group). The degree of prostatic hyperplasia was evaluated with a score-chart protocol, histoscore. The percent area density of epithelium and stroma of the ventral prostate were determined using a computerized image analysis system.

RESULTS

Definite lesions of hyperplastic changes were demonstrated in the ventral prostate of SH rats from 15 to 54 weeks. In comparison with WKY rats, SH rats showed a significantly increased degree of prostatic hyperplasia as reflected by the histoscore values. Furthermore, the histoscore of the ventral prostate of SH rats increased with age (from 21.7 +/- 0.7 at 15 weeks to 26.1 +/- 0.4 at 54 weeks). The percent area density of epithelium and stroma were significantly increased in SH rats, and the ratio of stroma to epithelium ranged from 1:2.94 to 1:3.50 in SH rats but was maintained at 1:1.15 to 1:1.19 in WKY rats during the observation period.

CONCLUSIONS

The hyperplastic changes of the ventral prostate may develop with advancing age in SH rats. The development of prostatic hyperplasia may result from both epithelial and stromal proliferation and may be predominantly expressed as a glandular type in SH rats.

The response of extracellular signal-regulated kinase (ERK) to androgen-induced proliferation in the androgen-sensitive prostate cancer cell line, LNCaP

The mechanisms by which androgens stimulate proliferation of prostate cancer cells are poorly understood. It has been proposed that androgen stimulation may induce the mitogen-activated protein (MAP) kinase system in prostate cancer cells and lead to cellular proliferation. We attempted to evaluate the role of the extracellular signal-regulated kinase (ERK) pathway in the stimulation by androgens of prostate cancer cell proliferation. Androgen-sensitive prostate cancer cell line (LNCaP) cells plated on sterile glass coverslips were treated with 10(-8) M dihydrotestosterone (DHT) or epidermal growth factor (EGF) (10 ng/ml) for periods ranging from 1 min to 96 h. The proliferative index of the cells, evaluated by immunoperoxidase staining of cells with an antibody to Ki-67, was increased at least two-fold at all time points from 5 min to 48 h following exposure to either DHT or EGF. Immunohistochemical evaluation of ERK1/2 and pERK (activated ERK) demonstrated high levels of ERK1/2 in untreated LNCaP cells, while pERK was expressed at much lower levels. Following treatment with DHT, no change in staining intensity for either ERK1/2 or pERK was observed, while treatment with EGF resulted in no change in ERK1/2, but significantly increased cytoplasmic staining for pERK at all time points beyond 2 min. These results were confirmed by Western blot analysis of ERK1/2 and pERK expression in these cell lines following treatment with DHT or EGF. Our findings suggest that the proliferative response of prostate cancer cells to androgens, unlike the proliferative response to EGF, is not mediated by the activation of ERK1/2, and that currently undefined pathways other than those involving ERK1/2 are involved.

Testosterone is a potential augmentor of antioxidant-induced apoptosis in human prostate cancer cells

We have investigated the effect of antioxidant-induced apoptosis in human prostate cancer cell lines that is augmented by testosterone (T). In this study, DU-145 (androgen unresponsive), ALVA-101 (partially androgen responsive), and LNCaP (androgen responsive) were grown in tissue culture with RPMI 1640 medium, 5-10% fetal bovine serum (FBS), antibiotics and 5% CO2. Treatment with 2.5-20 microg/ml of PDTC significantly (P < 0.05, n = 6) lowered cell growth in all three cells 2-60% following treatment for 1-7 days. T (10(-12) M) alone enhances cell growth in androgen responsive cells. In contrast, the combination of PDTC and T significantly (P < 0.05, n = 6) augmented the PDTC induction of apoptosis in the androgen responsive cells, (ALVA-101 and LNCaP), but not in the androgen unresponsive cells (DU-145). PDTC reduced the nuclear NF-KB, as determined with an electrophoretic mobility shift assay (EMSA), to 50% of the control in LNCaP cells, 65% in ALVA-101 cells and 45% in DU-145 cells, but the combination of PDTC and T was not more potent than PDTC alone in any of the cell lines. PDTC suppressed both the AR mRNA and protein expression and reversed the stimulatory effect of T on androgen receptor (AR) protein synthesis in LNCaP and AVLA-101 cells. In conclusion, PDTC is a potent growth inhibitor and an inducer of apoptosis in human prostate cancer cells by reducing nuclear NF-kappaB and AR protein expression. PDTCs suppression of AR synthesis and nuclear NF-kappaB in response to T may contribute to its enhancement of apoptosis observed with T and PDTC compared to PDTC alone.

Effects of cyclic stretch on prostatic cells in culture

PURPOSE

The fundamental process in the development of benign prostatic hyperplasia (BPH) is a loss of homeostasis between cell proliferation and apoptosis. Prostatic smooth muscle cells contract under adrenergic control. The response of a cell to stretch may have a role in the pathogenesis of BPH.

MATERIALS AND METHODS

Monolayer cultures of human prostatic stromal and epithelial cell lines were exposed to cyclic stretch for 48 hours.

RESULTS

Cyclic stretch conferred resistance to etoposide induced apoptosis. Underlying this apoptotic resistance was increased expression of the anti-apoptotic Bcl-2 family of proteins. As measured by thymidine incorporation, the rate of proliferation also increased in benign epithelial cells under cyclic stretch conditions. Furthermore, an increase in the production of platelet-derived growth factor by stromal cells and transforming growth factor-beta by epithelial cells occurred under such conditions.

CONCLUSIONS

The observed changes in proliferation and apoptosis may contribute to the understanding of BPH, ultimately leading to therapeutic and preventive applications.

Progressive prostate hyperplasia in adult prolactin transgenic mice is not dependent on elevated serum androgen levels

BACKGROUND

Transgenic mice overexpressing the rat prolactin (PRL) gene under control of the metallothionein-1 promoter (Mt-1) develop a dramatic prostatic enlargement. These animals also display significantly elevated testosterone serum levels. In this study, we aim to clarify the role of circulating androgen levels in the promotion of abnormal prostate growth in the adult PRL transgenic mouse prostate.

METHODS

Prostate morphology and androgen-receptor distribution patterns were analyzed in castrated and testosterone substituted adult PRL transgenic and in wild-type males.

RESULTS

Progressive prostatic hyperplasia in adult PRL transgenic males was not affected by substitution to serum testosterone levels corresponding to wild-type. Furthermore, prolonged testosterone treatment in adult wild-type males did not produce any significant changes in prostate growth or morphology compared with wild-type controls. Immunohistochemical studies revealed a significantly increased proportion of androgen receptor positive epithelial cells in all lobes of the PRL transgenic prostate versus wild-type.

CONCLUSION

The present study demonstrates that progressive prostate hyperplasia in adult PRL transgenic mice is not dependent on elevated serum androgen levels. Furthermore, prolonged androgen treatment in adult wild-type male mice appears to have no significant effect on prostate growth. In addition, our results suggest that prolonged hyperprolactinemia results in changes in prostate epithelial and stromal cell androgen receptor distribution.

Inhibition of nuclear factor κB induces apoptosis following treatment with tumor necrosis factor α and an antioxidant in human prostate cancer cells

Transforming growth factor beta-1 (TGFbeta-1) and tumor necrosis factor alpha (TNF-alpha), an activator of nuclear factor kappa B (NF-kappaB), modulate apoptosis and/or cell growth. This study was designed to investigate the activity of NF-kappaB and its regulation of inhibitor of apoptosis gene (c-IAP2) in two human prostate cancer cell lines, DU-145 (which is androgen unresponsive) and ALVA-101 (which is moderately androgen responsive). These cells were treated with and without various concentrations of a strong antioxidant, pyrrolidinedithiocarbamate (PDTC), and TNF-alpha at various time intervals. Following treatments, cell growth and apoptosis were determined by ELISA techniques. NF-kappaB activity was determined by electrophoretic mobility shift assay (EMSA), and c-IAP2 mRNA production was determined with Northern blot analysis. PDTC treatment significantly reduced cell growth up to 80% in both DU-145 and ALVA-101 cells. TNF-alpha and lower but not higher doses of PDTC combined demonstrated an additive inhibition of cell growth in both cell lines. Active NF-kappaB and c-IAP2 was blocked significantly following PDTC treatments, whereas treatments with TNF-alpha alone showed increased NF-kappaB activity and c-IAP2. However, when both PDTC and TNF-alpha were combined, nuclear presence of NF-kappaB and c-IAP2 were reduced significantly (P < 0.05) to levels observed with PDTC alone. In conclusion, the antioxidant, PDTC, appears to initiate apoptosis by blocking cytoplasmic NF-kappaB translocation to the nucleus where it normally activates the production of apoptosis-inhibitory proteins like c-IAP2. Both TNF-alpha and PDTC alone cause apoptosis and reduce cell growth, but their combined effects are additive in reducing cell growth of DU-145 and ALVA-101 human prostate cancer cells.

Hormonal treatment of patients with benign prostatic hyperplasia: pros and cons

The recognition that dihydrotestosterone is a "major player" in the development of benign prostatic hyperplasia (BPH) provided an impetus for the development of a 5a-reductase inhibitor, finasteride. During the past 5 years, a number of publications have noted that alpha blockers appear more efficacious than finasteride. This article reviews the role of hormones (particularly finasteride) in the treatment of lower urinary tract symptoms caused by BPH. These observations indicate that finasteride has a role in the management of larger prostates. Long-term use reduces the development of urinary retention and need for invasive procedures such as transurethral prostatectomy. The major adverse impact of finasteride is its effect on the patient's libido and sexual function. This is a less morbid problem for the elderly than the potential syncope associated with the use of alpha blockers. A greater understanding of the interaction of hormones on prostate receptors will provide newer tools for the treatment of BPH.

Growth factors: roles in andrology

Mesenchymal-epithelial interactions are extremely important during growth and development and in the functional cytodifferentiation of male sex accessory organs. Interactions between mesenchyme and epithelium occur mainly through a paracrine action that is mediated by various growth factors. The role of androgens is very important for these organs and the androgenic effect is mediated by paracrine interactions. A number of growth factors have been studied in prostate and seminal vesicles from mice, rats, and humans because they are potent mediators of cellular proliferation, differentiation, and death. This review provides an overview of current knowledge about growth factors involved in the development of male sex accessory organs, with particular emphasis on the prostate.

Alterations in lipoxygenase and cyclooxygenase-2 catalytic activity and mRNA expression in prostate carcinoma

Recent studies in prostate tissues and especially cell lines have suggested roles for arachidonic acid (AA) metabolizing enzymes in prostate adenocarcinoma (Pca) development or progression. The goal of this study was to more fully characterize lipoxygenase (LOX) and cyclooxygenase-2 (COX-2) gene expression and AA metabolism in benign and malignant prostate using snap-frozen tissues obtained intraoperatively and mRNA analyses and enzyme assays. Formation of 15-hydroxyeicosatetraenoic acid (15-HETE) was detected in 23/29 benign samples and 15-LOX-2 mRNA was detected in 21/25 benign samples. In pairs of pure benign and Pca from the same patients, 15-HETE production and 15-LOX-2 mRNA were reduced in Pca versus benign in 9/14 (P=.04) and 14/17 (P=.002), respectively. Under the same conditions, neither 5-HETE nor 12-HETE formation was detectable in 29 benign and 24 tumor samples; with a more sensitive assay, traces were detected in some samples, but there was no clear association with tumor tissue. COX-2 mRNA was detected by nuclease protection assay in 7/16 benign samples and 5/16 tumors. In benign and tumor pairs from 10 patients, COX-2 was higher in tumor versus benign in only 2, with similar results by in situ hybridization. Paraffin immunoperoxidase for COX-2 was performed in whole mount sections from 87 additional radical prostatectomy specimens, with strong expression in ejaculatory duct as a positive control and corroboration with in situ hybridization. No immunostaining was detected in benign prostate or tumor in 45% of cases. Greater immunostaining in tumor versus benign was present in only 17% of cases, and correlated with high tumor grade (Gleason score 8 and 9 vs. 5 to 7). In conclusion, reduced 15-LOX-2 expression and 15-HETE formation is the most characteristic alteration of AA metabolism in Pca. Increased 12-HETE and 5-HETE formation in Pca were not discernible. Increased COX-2 expression is not a typical abnormality in Pca in general, but occurs in high-grade tumors.

Selective estrogen receptor modulators for the chemoprevention of prostate cancer

The ability to interfere with prostate carcinogenesis, and as a consequence, prevent prostate cancer with drugs is the basis for chemoprevention. The prostate contains estrogen receptors in both the stroma and epithelium. Both animal models and human epidemiologic studies have implicated estrogens as an initiator of prostate cancer. In the aging male, prostate cancer occurs in an environment of rising estrogen and decreasing androgen levels. Selective estrogen receptor modulators (SERMs) have shown the ability to prevent (GTx-006 [acapodene]) and treat (GTx-006 and arzoxifene) prostate cancer, suggesting that they may be used in prostate cancer chemoprevention. A phase 2 clinical trial using GTx-006 for prostate cancer chemoprevention is currently being conducted.

Proliferation and differentiation of prostatic stromal cells

OBJECTIVES

To investigate the effects of androgen, transforming growth factor beta1 (TGF-beta) and basic fibroblast growth factor (bFGF) on the proliferation and differentiation of prostatic stromal cells of the dog in vivo and human stromal cells in vitro.

MATERIALS AND METHODS

Twenty-two dogs had their serum concentration of testosterone and oestradiol determined by radioimmunoassay before and after castration. Light microscopy, transmission electron microscopy and an in situ cell-death assay were carried out successively before and after castration to evaluate prostatic histomorphology. A semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was used to evaluate the expression of TGF-beta, bFGF and myosin in the canine prostate tissue after castration. In vitro serum-free cell cultures from human prostatic stroma were established and exposed to dihydrotestosterone (DHT), TGF-beta and bFGF in various concentrations. The proliferation of the cell cultures was detected by the tetrazolium assay. The differentiation from fibroblasts to smooth muscle cells (SMCs) was deduced by measuring the expression of SMC-specific proteins (myosin and smoothelin) using immunohistochemistry and RT-PCR.

RESULTS

Castration resulted in a significant decrease in circulating testosterone levels (P < 0.01), but did not affect the circulating oestradiol levels (P > 0.05). The prostatic stromal cells, including SMCs and fibroblasts, diminished and underwent a serial pathological change of atrophy and apoptosis after castration. The atrophic cells were filled with intracellular lipofuscin. The expression of SMC myosin declined after castration, coincident with the increase in TGF-beta mRNA level and decline in bFGF mRNA. In vitro, TGF-beta inhibited the growth of human prostatic stromal cells during exponential growth, while enhancing myosin staining and stimulating the expression of smoothelin in confluent cultured stromal cells. bFGF stimulated the growth of the culture and inhibited the expression of smoothelin. DHT caused a weak increase in the proliferation and expression of SMC-specific proteins (P < 0.05). However, DHT and bFGF together stimulated the proliferation of stromal cells significantly more than either agent alone (P < 0.01). The combination of DHT and TGF-beta greatly enhanced the expression of SMC-specific proteins (P < 0.01), more strongly than either alone (P < 0.01).

CONCLUSIONS

The whole prostate gland is an androgen-sensitive organ, with both the epithelium and stroma under the control of androgen. Androgen may direct the proliferation and differentiation of prostatic stromal cells by regulating the expression of TGF-beta and bFGF. Thus DHT, TGF-beta and bFGF may have important roles in regulating stromal cell homeostasis.