TESTOSTERONE INDUCES VASCULAR ENDOTHELIAL GROWTH FACTOR SYNTHESIS IN THE VENTRAL PROSTATE IN CASTRATED RATS

The Role of Reactive Oxygen Species, Inflammation, and Endoplasmic Reticulum Stress Response in the Finasteride Protective Effect against Benign Prostate Hyperplasia

PURPOSE

Benign prostate hyperplasia (BPH) is a common age-related chronic condition. Its pathogenesis involves androgen imbalance, inflammation, oxidative stress, and endoplasmic reticulum (ER) stress. This study aims to assess the protective effect of finasteride, a 5α-reductase inhibitor, against testosterone propionate (TP)-induced BPH in rats and explore its potential mechanism of action.

MATERIALS AND METHODS

TP-induced BPH rats received either saline or finasteride (1 mg/kg) orally once a day for 7 weeks. Prior to sacrificing the animals, blood samples were collected. After sacrifice, prostate and tissue around the prostate were dissected from seminal vesical for further analysis. Body weight, prostate weight, dihydrotestosterone (DHT), 5α-reductase type 2 (5-AR2), and prostate-specific antigen (PSA) levels were measured. In addition, HIF-1α, VEGF, MMP-2 expressions in prostate, oxidative stress, inflammation, and ER stress responses were analyzed to understand the mechanism of action of finasteride.

RESULTS

Finasteride administration inhibited prostate enlargement, DHT, 5-AR2, and PSA levels in BPH rats. Additionally, finasteride inhibited angiogenesis markers such as HIF-1α, VEGF, and MMP-2. Moreover, components of oxidative stress, inflammation, and ER stress responses were significantly regulated by finasteride treatment.

CONCLUSIONS

This study suggests that finasteride prevents BPH-associated symptoms by regulating angiogenesis, reactive oxygen species, ER stress responses, and inflammation, another mechanism to explain the effect of the 5α-reductase against BPH.

Testosterone improved erectile function by upregulating transcriptional expression of growth factors in late androgen replacement therapy model rats

We previously showed that castration of rats reduced erectile function over time; when testosterone replacement therapy was started 4 weeks after castration, erectile function improved. In this study, we examined the mechanism of improvement in erectile function following testosterone replacement therapy in rats. Thirty 12-week-old rats were divided into castrated (Cast), castrated with subcutaneous administration of testosterone (Cast + T), and sham (Sham) groups. Erectile function and mRNA and protein expression were evaluated in the rats by using standard methods. To assess erectile function, we measured the intracavernosal pressure, mean arterial pressure, mRNA expression of endothelial growth factors, and protein expression of endothelial nitric oxide synthase (eNOS). The intracavernosal pressure/mean arterial pressure ratio was significantly lower in the Cast group, and testosterone administration significantly improved (P = 0.017). Compared to the Cast group, the Cast+T group exhibited significantly increased mRNA expressions of vascular endothelial growth factor A (VEGF-A), intercellular adhesion molecule 1 (ICAM-1), transforming growth factor-β (TGF-β), nerve growth factor (NGF), α-smooth muscle actin (α-SMA), caveolae associated protein 1 (Cavin-1), Cavin-2, Cavin-3, sirtuin 1 (Sirt-1), sphingosine-1-phosphate 1 (S1P1), S1P2, and S1P3 and eNOS protein expression. Testosterone replacement therapy improved erectile function in castrated rats by increasing growth factors and eNOS protein.

How VEGF-A and its splice variants affect breast cancer development - clinical implications

BACKGROUND

Altered expression levels and structural variations in the vascular endothelial growth factor (VEGF) have been found to play important roles in cancer development and to be associated with the overall survival and therapy response of cancer patients. Particularly VEGF-A and its splice variants have been found to affect physiological and pathological angiogenic processes, including tumor angiogenesis, correlating with tumor progression, mostly caused by overexpression. This review focuses on the expression and impact of VEGF-A splice variants under physiologic conditions and in tumors and, in particular, the distribution and role of isoform VEGF165b in breast cancer.

CONCLUSIONS AND PERSPECTIVES

Many publications already highlighted the importance of VEGF-A and its splice variants in tumor therapy, especially in breast cancer, which are summarized in this review. Furthermore, we were able to demonstrate that cytoplasmatic VEGFA/165b expression is higher in invasive breast cancer tumor cells than in normal tissues or stroma. These examples show that the detection of VEGF splice variants can be performed also on the protein level in formalin fixed tissues. Although no quantitative conclusions can be drawn, these results may be the starting point for further studies at a quantitative level, which can be a major step towards the design of targeted antibody-based (breast) cancer therapies.

KLK3 in the Regulation of Angiogenesis-Tumorigenic or Not?

In this focused review, we address the role of the kallikrein-related peptidase 3 (KLK3), also known as prostate-specific antigen (PSA), in the regulation of angiogenesis. Early studies suggest that KLK3 is able to inhibit angiogenic processes, which is most likely dependent on its proteolytic activity. However, more recent evidence suggests that KLK3 may also have an opposite role, mediated by the ability of KLK3 to activate the (lymph)angiogenic vascular endothelial growth factors VEGF-C and VEGF-D, further discussed in the review.

Biochemistry of the menopause

The life of a human female is characterized from teenage years by monthly menstruation which ceases (the menopause) typically between the age of 40 and 60 years. The potential for reproduction declines and ceases as the ovaries become depleted of follicles. A transition period in mid-life, for 2 to 10 years, when menstruation is less regular is called the perimenopause. The menopause is associated with a significant decline in plasma concentrations of sex hormones, an increase in the concentrations of the gonadotrophins and changes in other hormones such as the inhibins. These changes are superimposed with effects of aging, social and metabolic factors, daily activity and well-being. Although the menopause is entirely natural, in some cases ovarian failure can occur earlier than usual; this is pathological and warrants careful biochemical investigations to distinguish it from conditions causing infertility. Elderly females are affected by a range of clinical disorders including endocrine, cardiovascular, skeletal, urogenital tract and immunological systems, body mass, vasomotor tone, mood and sleep pattern. Reference intervals for many diagnostic biochemical tests for the menopause need to be used when interpreting results in clinical investigations for patient management. The standardization and harmonization of assays are being addressed. Many women now choose to develop their career before bearing children, and the health service has had to change services around this. This review does not cover screening for and tests during pregnancy. The review is timely since the population is aging and there will be more demand on healthcare services.

Variable expression of molecular markers in juvenile nasopharyngeal angiofibroma

Background:

Molecular categorisation may explain the wide variation in the clinical characteristics of juvenile nasopharyngeal angiofibroma.

Methods:

Variations in molecular markers in juvenile nasopharyngeal angiofibroma in an Indian population were investigated and compared with global reports.

Results:

Variable molecular marker expression was demonstrated at the regional and global levels. A wide variation in molecular characteristics is evident. Molecular data have been reported for only 11 countries, indicating a clear geographical bias. Only 58 markers have been studied, and most are yet to be validated.

Conclusion:

Research into the molecular epidemiology of juvenile nasopharyngeal angiofibroma is still in its infancy. Although the molecular variation is not well understood, data obtained so far have prompted important research questions. Hence, multicentre collaborative molecular studies are needed to establish the aetiopathogenesis and establish molecular surrogates for clinical characteristics.

Venous malformation: risk of progression during childhood and adolescence

Venous malformations (VMs) can cause significant morbidity, particularly because they enlarge over time and become symptomatic. The purpose of this study was to determine the natural progression of VMs to facilitate patient counseling, gain insight into pathophysiology, and guide therapy. Our Vascular Anomalies Center database was reviewed for patients with cutaneous and soft-tissue VMs. Predictive variables were age, gender, location, pregnancy, and size. The outcome variable was natural progression of the malformation defined by expansion of the lesion or the onset/worsening of symptoms. The study included 614 patients. Children had a 26.1% risk of progression prior to adolescence, 74.9% before adulthood, and 93.2% over their lifetime. Progression was more likely in adolescence (60.9%) than in childhood (22.5%); the relative risk was 2.6 (95% confidence interval, 2.1-3.2) (P = 0.0001). Diffuse VMs progressed more often than localized lesions (P = 0.002); extremity and trunk VMs worsened more frequently than head/neck lesions (P = 0.03). VMs have a higher risk of progression in adolescents than in children; pubertal hormones may contribute to expansion. Because of their high rate of progression, early treatment of asymptomatic VMs should be considered.

Expression of androgen, estrogen, progesterone, and growth hormone receptors in vascular malformations

BACKGROUND

Vascular malformations frequently enlarge during adolescence, suggesting that hormones may be involved. The purpose of this study was to determine whether pubertal hormone receptors are present in vascular malformations and whether they differ from normal tissue.

METHODS

Tissue specimens (arteriovenous malformation, lymphatic malformation, and venous malformation) were prospectively collected from patients undergoing resection. Immunohistochemistry was used to determine the presence of androgen, estrogen, progesterone, and growth hormone receptors. The effects of age, sex, location, and malformation type on receptor expression were analyzed. Age-, sex-, and location-matched normal tissues served as controls.

RESULTS

Forty-five vascular malformation specimens were collected: arteriovenous malformation (n = 11), lymphatic malformation (n = 20), and venous malformation (n = 14). Growth hormone receptor expression was increased in arteriovenous malformation (72.7 percent), lymphatic malformation (65.0 percent), and venous malformation (57.1 percent) tissues compared with controls (25.8 percent) (p < 0.05). Growth hormone receptor was present primarily in the endothelium/perivasculature of malformations (93.1 percent), whereas in normal tissue growth hormone receptor was located only in the stroma (p < 0.0001). Neither age, nor sex, nor location influenced receptor expression (p = 0.9). No differences in androgen receptor, estrogen receptor, and progesterone receptor staining were found between malformations and control samples (p = 0.7).

CONCLUSIONS

Growth hormone receptor is overexpressed and principally located in the vessels of vascular malformations. Growth hormone might contribute to the expansion of vascular malformations.

Primary xenografts of human prostate tissue as a model to study angiogenesis induced by reactive stroma

Characterization of the mechanism(s) of androgen-driven human angiogenesis could have significant implications for modeling new forms of anti-angiogenic therapies for CaP and for developing targeted adjuvant therapies to improve efficacy of androgen-deprivation therapy. However, models of angiogenesis by human endothelial cells localized within an intact human prostate tissue architecture are until now extremely limited. This report characterizes the burst of angiogenesis by endogenous human blood vessels in primary xenografts of fresh surgical specimens of benign prostate or prostate cancer (CaP) tissue that occurs between Days 6–14 after transplantation into SCID mice pre-implanted with testosterone pellets. The wave of human angiogenesis was preceded by androgen-mediated up-regulation of VEGF-A expression in the stromal compartment. The neo-vessel network anastomosed to the host mouse vascular system between Days 6–10 post-transplantation, the angiogenic response ceased by Day 15, and by Day 30 the vasculature had matured and stabilized, as indicated by a lack of leakage of serum components into the interstitial tissue space and by association of nascent endothelial cells with mural cells/pericytes. The angiogenic wave was concurrent with the appearance of a reactive stroma phenotype, as determined by staining for α-SMA, Vimentin, Tenascin, Calponin, Desmin and Masson's trichrome, but the reactive stroma phenotype appeared to be largely independent of androgen availability. Transplantation-induced angiogenesis by endogenous human endothelial cells present in primary xenografts of benign and malignant human prostate tissue was preceded by induction of androgen-driven expression of VEGF by the prostate stroma, and was concurrent with and the appearance of a reactive stroma phenotype. Androgen-modulated expression of VEGF-A appeared to be a causal regulator of angiogenesis, and possibly of stromal activation, in human prostate xenografts.

A systematic review of the effects and mechanisms of preoperative 5α-reductase inhibitors on intraoperative haemorrhage during surgery for benign prostatic hyperplasia

5α-reductase inhibitors (5α-RIs), including finasteride and dutasteride, are commonly used medical therapies for benign prostatic hyperplasia (BPH). Many studies reported that preoperative 5α-RI had impact on intraoperative haemorrhage during surgery for BPH, but it was still in controversial. So, we conducted a systematic review of the effects and mechanisms of 5α-RIs on intraoperative bleeding for BPH. MEDLINE, EMBASE, the Cochrane Controlled Trail Register of Controlled Trials and the reference lists of retrieved studies were searched in the analysis. Sixteen publications involving 15 different randomized controlled trials (RCTs) and a total of 1156 patients were used in the analysis, including 10 RCTs for finasteride and five RCTs for dutasteride. We found that preoperative finasteride treatment decreases microvessel density (MVD) in resected prostate specimens. Total blood loss, blood loss per gram of resected prostate tissue and decreases in haemoglobin were all greatly reduced in the finasteride group as compared to controls. Dutasteride appeared to have no effect on bleeding. This meta-analysis shows that preoperative finasteride treatment could decrease intraoperative haemorrhage during surgery for BPH. Preoperative dutasteride had no effect on intraoperative haemorrhage, but further high-quality prospective studies are still needed to confirm this observation.

Effects of androgen on the expression of vascular endothelial growth factor in the penile corpus cavernosum

OBJECTIVES

To investigate the effect of orchiectomy and androgen replacement on the expression of vascular endothelial growth factor (VEGF) in rat penile tissue.

MATERIAL AND METHODS

Adult male Sprague-Dawley rats (12 weeks old) were left intact (control) or surgically castrated. Orchiectomized rats were left untreated or received testosterone propionate (TP) for 7 days, beginning 1 or 2 weeks after castration. Erectile function was assessed by measuring intracavernosal pressure in response to cavernous nerve stimulation, and the expression of VEGF protein and mRNA was determined by immunohistochemistry, Western blot analysis, and reverse transcriptase-polymerase chain reaction. Serum testosterone values were measured in each animal by radioimmunoassay.

RESULTS

Serum androgen levels decreased significantly in castrated animals, whereas TP injection normalized the serum levels of testosterone. Intracavernosal pressure was significantly decreased in untreated castrated rats (31.3 ± 15.7% at 2 weeks postcastration; 18.6 ± 4.6% at 3 weeks postcastration) compared with intact controls (58.0 ± 11.4% and 58.9 ± 8.2%, respectively). Erectile function was normalized in androgen-replaced rats, irrespective of treatment was initiation 1 or 2 weeks after orchiectomy. The expression of VEGF protein and mRNA was decreased in the corpus cavernosum of castrated animals compared with controls, whereas androgen replacement normalized the expression of VEGF. These results were consistently observed by all 3 methods of assessment.

CONCLUSIONS

These data suggest that androgen regulates the expression of VEGF in rat penile corpus cavernosum and confirms the importance of androgens in the maintenance of erectile function.

Effects of steroid hormones on morphology and vascular endothelial growth factor expression in female bladder

OBJECTIVES

To investigate the roles of steroid hormones, including estrogen, progesterone, and testosterone, in the morphology and vascularization of the female bladder.

METHODS

A total of 70 adult, female Sprague-Dawley rats were divided into 7 groups: group 1, sham; group 2, ovariectomized rats without treatment; group 3, low-dose estradiol; group 4, high-dose estradiol; group 5, progesterone; group 6, estradiol combined with progesterone; and group 7, testosterone. All were given for 4 weeks. The serum steroid hormone levels were determined by radioimmunoassay. The total weight and thickness of the bladder were measured. Morphologic changes were observed under light and electron microscopy. The expression of vascular endothelial growth factor (VEGF) in the bladder was evaluated by immmohistochemistry and Western blotting.

RESULTS

The ovariectomized rats had a thinner bladder wall compared with the sham group (0.97 +/- 0.11 mm vs 1.10 +/- 0.10 mm, P < .05) and widened spaces between the detrusor muscle fascicles with collagen deposit. Estrogen reversed these changes, and testosterone increased the thickness of the bladder wall to 1.26 +/- 0.12 mm (P < .05). VEGF staining was mainly located in the urothelium and endothelial cells, with weak staining in the smooth muscles. VEGF was almost absent in the urothelium after ovariectomy. In the estrogen- and androgen-treated groups, although the expression of VEGF was significantly greater than that in the nontreated ovariectomized group, it was still lower than normal.

CONCLUSIONS

Our findings suggest the importance of steroid hormones in maintaining the integrity of the bladder structure and regulating the expression of VEGF in the female urinary tract. Both estrogen and androgen can reverse the bladder muscle atrophy induced by ovariectomy. However, the decline in VEGF expression in the bladder cannot be fully recovered with either estrogen or androgen replacement.

The use of gene transfer technology to study the pathophysiology of erectile dysfunction

INTRODUCTION

The past 25 years of basic science research on erectile physiology has been devoted to investigating the pathogenesis of erectile dysfunction. Research has led to a better understanding of the biochemical factors and intracellular mechanisms responsible for corporal smooth muscle contraction and relaxation, as well as the influence of endothelial-derived relaxing factors.

AIM

In this essay, we propose the use of gene transfer technology to study mechanisms of disease involved in penile vascular dysfunction.

METHODS

The development of methods to deliver therapeutic genes to the penis has kindled a keen interest in treating ED with gene- and cell-based therapies.

RESULTS

Gene therapy has delineated putative mechanisms of disease in animal models of erectile dysfunction.

CONCLUSION

Investigation of animal models using gene therapy may ultimately lead to mechanism-based therapies for the treatment of erectile dysfunction.

Altered expression of genes regulating angiogenesis in experimental androgen-independent prostate cancer

BACKGROUND

The aim of this study was to investigate how the expression of genes regulating angiogenesis is altered when prostate cancer cells progress into androgen-independency.

METHODS

A gene array specific for angiogenesis was used to compare the human prostate cancer cell line LNCaP (androgen-dependent) with its more angiogenic and tumorigenic subline LNCaP-19 (androgen-independent). Results were verified with real-time RT-PCR, and further investigations were focused on the angiogenesis inhibitor a disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1). Expression of ADAMTS1 was investigated in vitro as well as in subcutaneous tumors with real-time RT-PCR and Western blotting. Microvessel density (MVD), versican proteolysis and protein levels of TIMP-2 and TIMP-3, known as ADAMTS1 inhibitors, were also analyzed in tumor xenografts.

RESULTS

The gene array revealed decreased expression of ADAMTS1, ephrin-A5, fibronectin 1, and neuropilin 1 in LNCaP-19 compared to LNCaP, while expression of midkine and VEGF were increased. Further studies showed that mRNA and protein levels of ADAMTS1 were significantly lower in LNCaP-19 compared to LNCaP, both in vitro and in subcutaneous tumors. The amount of ADAMTS1 correlated negatively with MVD, but no relation was found between ADAMTS1 and versican proteolysis.

CONCLUSIONS

Expression of several genes associated with angiogenesis was altered during transition into androgen-independency. Among these, a significant decrease was found for ADAMTS1, whose expression inversely correlated with MVD. Its role in progression of prostate cancer needs further investigation, but this inhibitor of angiogenesis could be an interesting candidate for future anti-angiogenic therapy.

A phase II evaluation of goserelin and bicalutamide in patients with ovarian cancer in second or higher complete clinical disease remission

BACKGROUND

The current study was conducted to determine the effect of goserelin and bicalutamide on progression-free survival (PFS) in patients with epithelial ovarian cancer who were in second or greater complete disease remission.

METHODS

Patients received bicalutamide at a dose of 50 mg orally daily and goserelin at a dose of 3.6 mg subcutaneously every 4 weeks. CA 125 was obtained monthly, with computed tomography performed every 3 months. Correlative studies included serum luteinizing hormone, follicle-stimulating hormone, vascular endothelial growth factor, free testosterone, and androstenedione and the germline polymorphisms CYP19A1 and androgen receptor.

RESULTS

Between October of 2000 and October of 2002, 35 patients were enrolled. Three patients (9%) received therapy at the time of first disease remission and were removed from the study, and 1 patient (3%) was removed for liver function test abnormalities. The most frequent toxicities were grade 1 alkaline phosphatase (54%), fatigue (57%), and hot flashes (42%) based on the National Cancer Institute common toxicity scale, version 2.0. The PFS for patients receiving protocol therapy in second disease remission (21 patients) was 11.4 months (95% confidence interval [95% CI], 10.2-12.6 months). The PFS for patients receiving protocol therapy in third or fourth disease remission (11 patients) was 11.9 months (95% CI, 10.8-14.1 months). The percentage of patients remaining in second disease remission at given times are: 100% at 3 months, 100% at 6 months, 72% at 9 months, 47% at 12 months, 28% at 15 months, 22% at 18 months, 19% at 21 months, and 13% at 24 months. There were no associations noted between androgen receptor repeat number, genotype, allelotype, or haplotypes and PFS.

CONCLUSIONS

The use of goserelin and bicalutamide did not appear to prolong PFS in patients with epithelial ovarian cancer in second or greater complete disease remission. The number of patients in disease remission at given time points may serve as a clinical trial endpoint for future studies of consolidation therapy.

Vascular density is highest in the proximal region of the mouse prostate

BACKGROUND

The proximal region of the prostatic ducts harbor the prostatic epithelial stem cells. As stem cell niches in other organs are highly vascularized, we determined if the proximal region is more highly vascularized than the remaining regions of the prostate. The effect of androgen on vascular density in the different prostatic regions was also examined.

METHODS

Sections from prostates were immunostained with antibodies to CD31, and the vascular density in proximal, intermediate, and distal regions was calculated by image analysis software. Vascular density was compared in prostates from castrated mice that received daily inoculations of testosterone or vehicle alone for 3 days. To examine the role of angiogenic factors in the response to androgen, some animals were also treated with soluble VEGF receptor-2-Fc or Tie-2--Fc fusion proteins, which inhibit the activities of VEGF and angiopoietins, respectively. The endothelial proliferative response to androgen was determined by double staining sections with antibodies to CD31 and Ki-67.

RESULTS

In prostates from intact mice, vascular density was highest in the proximal region and lowest in the distal region. Administration of testosterone to castrated mice increased vascular density to the greatest extent in the distal and intermediate regions. The increase in vascular density required VEGF and the angiopoietins. Endothelial cell proliferation was less sensitive to androgen in the proximal region than the remainder of the prostate.

CONCLUSIONS

Vascular density is highest in the proximal region of the prostate, but the proximal vessels are less responsive to testosterone.

Vascular endothelial growth factor and angiopoietin are required for prostate regeneration

BACKGROUND

The regulation of the prostate size by androgens may be partly the result of androgen effects on the prostatic vasculature. We examined the effect of changes in androgen levels on the expression of a variety of angiogenic factors in the mouse prostate and determined if vascular endothelial growth factor (VEGF)-A and the angiopoietins are involved in the vascular response to androgens.

METHODS

Expression of angiogenic factors in prostate was quantitated using real-time PCR at different times after castration and after administration of testosterone to castrated mice. Angiopoietins were localized in prostate by immunohistochemistry and in situ hybridization. The roles of VEGF and the angiopoietins in regeneration of the prostate were examined in mice inoculated with cells expressing soluble VEGF receptor-2 or soluble Tie-2.

RESULTS

Castration resulted in a decrease in VEGF-A, VEGF-B, VEGF-C, placenta growth factor, FGF-2, and FGF-8 expression after 1 day. In contrast, VEGF-D mRNA levels increased. No changes in angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), hepatocyte growth factor, VEGF receptor-1, VEGF receptor-2, or tie-2 mRNA levels were observed. Administration of testosterone to castrated mice had the opposite effect on expression of these angiogenic factors. Ang-2 was expressed predominantly in prostate epithelial cells whereas Ang-1 was expressed in epithelium and smooth muscle. Inoculation of mice with cells expressing soluble VEGF receptor-2 or Tie-2 blocked the increase in vascular density normally observed after administration of testosterone to castrated mice. The soluble receptors also blocked the increase in prostate weight and proliferation of prostatic epithelial cells.

CONCLUSION

VEGF-A and angiopoietins are required for the vascular response to androgens and for the ability of the prostate to regenerate in response to androgens.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Vascular endothelial growth factor (VEGF) signaling in tumor progression

Vascular endothelial cells are ordinarily quiescent in adult humans and divide less than once per decade. When tumors reach a size of about 0.2-2.0mm in diameter, they become hypoxic and limited in size in the absence of angiogenesis. There are about 30 endogenous pro-angiogenic factors and about 30 endogenous anti-angiogenic factors. In order to increase in size, tumors undergo an angiogenic switch where the action of pro-angiogenic factors predominates, resulting in angiogenesis and tumor progression. One mechanism for driving angiogenesis results from the increased production of vascular endothelial growth factor (VEGF) following up-regulation of the hypoxia-inducible transcription factor. The human VEGF family consists of VEGF (VEGF-A), VEGF-B, VEGF-C, VEGF-D, and placental growth factor (PlGF). The VEGF family of receptors consists of three protein-tyrosine kinases and two non-protein kinase receptors (neuropilin-1 and -2). Owing to the importance of angiogenesis in tumor progression, inhibition of VEGF signaling represents an attractive cancer treatment.

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

PURPOSE

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.

EXPERIMENTAL DESIGN

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.

RESULTS

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.

CONCLUSION

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.

Effects of finasteride on the vascular surface density, number of microvessels and vascular endothelial growth factor expression of the rat prostate

INTRODUCTION

Finasteride is a 5-alpha-reductase inhibitor used in the medical treatment of benign prostatic hyperplasia (BPH) and appears to be effective in treating prostatic bleeding secondary to BPH. The exact mechanism of this effect is not known. The aim of this study was to evaluate the effects of finasteride on the vascular surface density (VSD), number of microvessels (NVES) and vascular endothelial growth factor (VEGF) expression of the rat prostate.

MATERIALS AND METHODS

Nineteen adult male rats were used. Finasteride was given to 14, and there were 5 in the control group. Finasteride 80 mg/kg was administered daily via orogastric tube as a suspension for three months. Rats were sacrificed and vascular structures of the prostates were labelled immunohistochemically using CD31 antibodies. VSD and NVES of the prostates were assessed by means of a peroxidase labeled streptavidin-biotin method. VEGF expression was examined by immunohistochemistry using VEGF monoclonal antibody.

RESULTS

Mean prostatic weights were decreased significantly in rats given finasteride (p=0.0001). Although an increase in VSD was detected in the finasteride group it was not significant (p=0.26). NVES was significantly increased in the finasteride group (p=0.033). No significant difference was detected between the two groups in terms of VEGF expression (p=0.48).

CONCLUSION

Finasteride does not seem to decrease VSD, NVES and VEGF expression at the level of the rat prostate. The effect of reduction of bleeding in BPH is likely to be due to its effect on shrinking glandular hyperplasia which might enhance vessel wall stability rather than decreasing overall vascularity.

Angiogenesis imaging in the management of prostate cancer

Angiogenesis is an integral part of benign prostatic hyperplasia, is associated with prostatic intraepithelial neoplasia and is a key factor in the growth and metastasis of prostate cancer. This review focuses on ultrasound and dynamic MRI in the evaluation of prostate cancer angiogenesis, and compares these techniques to functional CT and hydrogen magnetic resonance spectroscopic imaging. Image-based evaluation of angiogenesis in the prostate has established clinical roles in lesion detection, tumor staging and the detection of suspected tumor recurrence. One limitation of all these imaging techniques, however, is inadequate lesion characterization, particularly in differentiating prostatitis from cancer in the peripheral zone of the prostate, and in distinguishing between benign prostatic hyperplasia and central-gland tumors. Ultimately, local availability, expertise and the need to minimize patients' radiation burden will influence which technique is used in prostatic evaluations.

Effect of short-term finasteride therapy on peroperative bleeding in patients who were candidates for transurethral resection of the prostate (TUR-P): a randomized controlled study

In the present study we aimed to demonstrate the efficacy of short-term pretreatment with finasteride in patients undergoing transurethral resection of the prostate (TUR-P). For this purpose 40 patients with BPH, who were candidates for TUR-P, were randomized into two groups. The first group (n=20) received 5 mg finasteride/day for 4 weeks prior to surgery and the second group (n=20) remained as the control. Patients who underwent prior prostate or urethral surgery and had a diagnosis of prostate cancer or chronic renal failure, patients who received finasteride, aspirin, coumadin or similar anticoagulant drugs prior to surgery and patients who had capsule perforations or open sinuses during the surgery were excluded from the study. All patients had a normal digital rectal examination and PSA values less than 4 ng/ml. As we look at the results there was no statistically significant difference between the finasteride group and control group regarding age, IPSS, PSA, prostate volumes, preoperative serum hemoglobin, hematocrit values and mean operating times and used irrigating fluids. The total amount of bleeding and bleeding per gram resected tissue were significantly lower in the finasteride group regardless of prostate volume. Furthermore the decrease in the hemoglobin and hematocrit values was higher in the control group. As a conclusion four weeks of finasteride pretreatment provided a significant decrease in peroperative bleeding regardless of prostate volume without any major side effects.

A role for cyclin A1 in mediating the autocrine expression of vascular endothelial growth factor in prostate cancer

Elevated levels of cyclin A1 expression have been implicated in acute myeloid leukemia and in male germ cell tumors. However, a role of cyclin A1 in tumorigenesis of prostate cancer has not been reported. In the present study, expression of cyclin A1 in patients with prostate cancer and a role of cyclin A1 in mediating expression of vascular endothelial growth factor (VEGF) were investigated. Cyclin A1 was highly expressed in aggressive tumors and was significantly correlated with VEGF expression in 96 patients with prostate cancer. Treatment of LNCaP cells with R1881, a synthetic androgen resulted in increased cyclin A1 expression. Induction of cyclin A1 expression in LNCaP cells led to an increase in VEGF expression and this effect was manifested upon the R1881 treatment. Cyclin A1 failed to mediate VEGF activation in DU-145 cells lacking a functional Rb and an androgen receptor (AR). Although AR expression was induced into DU-145 cells, cyclin A1 was unable to mediate VEGF expression. However, induced coexpression of cyclin A1, Rb and AR in DU-145 cells in the presence of R1881 greatly promoted VEGF promoter activity. This suggests that cyclin A1 mediates VEGF expression in cooperation with Rb- and androgen-dependent pathways in prostate cancer.

Effects of androgen suppression and radiation on prostate cancer suggest a role for angiogenesis blockade

Antiandrogen therapy is an important modality in the treatment of prostate cancer. Recent research into the role of angiogenesis in tumour growth and metastasis has uncovered links between antiandrogen therapy, radiation therapy and angiogenesis, which have exciting implications for the treatment of prostate cancer. Angiogenic cytokines such as vascular endothelial growth factor (VEGF) have been identified in prostate cancer cells and tumours, and androgens appear to stimulate VEGF. This article assesses the antiangiogenic effects of hormonal therapy and assesses the role that angiogenesis may play in the observed cooperation between hormonal and radiation therapies for prostate cancer.

Direct regulation of prostate blood flow by vascular endothelial growth factor and its participation in the androgenic regulation of prostate blood flow in vivo

Previous studies on prostate blood flow regulation have indicated that androgen regulates prostate blood flow. However, the mechanism responsible for this regulation is unknown. In the present study, we focused on the effects of vascular endothelial growth factor (VEGF), a key factor responsible for angiogenesis and androgenic blood flow regulation. We examined in vivo the effect of VEGF on prostate blood flow and its participation in the androgenic regulation of this blood flow using a castrated rat model following subcapsular intraprostatic injection method. We found that VEGF is involved in blood flow regulation with an activity equal to that of dihydrotestosterone (DHT). The effect of VEGF on prostate blood flow was already seen at 30 min after the administration. The elevating effect of DHT on castrated rat prostate blood flow was abolished by coadministration of DHT with neutralizing anti-VEGF antibody. The change in VEGF-A mRNA expression in response to androgen stimulation was examined by double-fluorescent probe quantitative PCR (Taqman PCR). The results showed that androgenic regulation of VEGF gene expression occurred shortly after androgen stimulation. VEGF gene up-regulation was abolished or down-regulated by coadministration of neutralizing anti-VEGF antibody. This is the first report on the importance of VEGF in the androgenic regulation signaling pathway that affects prostate blood flow. Alternative treatment targeted toward anti-VEGF activity as a substitute for ordinary antiandrogenic therapy may be effective against prostate diseases, especially those with androgen-independent and hyperhemorrhagic status.

An autocrine loop for vascular endothelial growth factor is established in prostate cancer cells generated after prolonged treatment with interleukin 6

Concentrations of interleukin 6 (IL-6) and its receptor are increased in human prostate cancer. Prostate cancer LNCaP-IL-6+ cells, established after prolonged treatment with IL-6, have been found to acquire a growth advantage. Vascular endothelial growth factor (VEGF) may accelerate the growth of various tumours by stimulation of VEGF receptor 2 (VEGFR-2). To understand better the regulation of proliferation of LNCaP-IL-6+ cells, the expression of VEGF and VEGFR-2 was here investigated in the LNCaP-IL-6+ subline. VEGF was measured in cellular supernatants by enzyme-linked immunoassay. The expression of VEGFR-2 was assessed by Western blot. LNCaP-IL-6+ and control LNCaP-IL-6- cells were treated with a neutralising antibody against VEGFR-2. VEGF concentrations were 20-fold higher in LNCaP-IL-6+ than in LNCaP-IL-6- cells. The stimulatory effect of IL-6 on VEGF production was abolished by an inhibitor of the signalling pathway for phosphoinositol 3 kinase in LNCaP-IL-6+ and LNCaP-IL-6- cells. Exogenous VEGF did not stimulate proliferation in either LNCaP-IL-6+ cells or controls. VEGFR-2 was detected only in LNCaP-IL-6+ cells, in which the neutralising antibody caused a partial inhibition of cell proliferation. It was concluded that a VEGF autocrine loop is established in prostate cancer cells generated after chronic treatment with IL-6. Because of the upregulation of IL-6 in patients with prostate cancer, these findings might be clinically relevant.

Quantitative proteomic analysis of proteins released by neoplastic prostate epithelium

Prostate cancer is unusual among neoplasms in that it may be diagnosed at a curable stage through detection of a protein in serum, the serine protease prostate-specific antigen (PSA). PSA is secreted by both normal and neoplastic prostate epithelial cells in response to androgenic hormones and has found widespread use in cancer screening. Because PSA screening is controversial due to sensitivity and specificity issues, efforts continue to focus on the identification and characterization of additional markers that may be used for diagnostic and therapeutic purposes. In this study, we report the application of quantitative proteomic techniques that incorporate isotope coded affinity tag reagents and tandem mass spectrometry to comprehensively identify secreted and cell surface proteins from neoplastic prostate epithelium. LNCaP cells, a prostate tumor-derived cell line that secretes PSA in response to androgen exposure, were grown in a low protein-defined media under androgen-stimulated (A+) and -starved (A-) conditions. Proteomic analysis of the media identified in excess of 600 proteins, 524 of which could be quantified. Nine percent of the proteins had A+/A- ratios > 2.0, including PSA, and 2.5% had ratios < 0.5. A subset of these androgen-regulated proteins appeared to be expressed in abundance. Of these, selected mass spectrometry observations were confirmed by Western analysis. The findings suggest that androgen-mediated release of proteins may occur through the activation of proteolytic enzymes rather than exclusively through transcriptional or translational control mechanisms. On the basis of their known functional roles, several of the abundant androgen-regulated proteins may participate in the progression of neoplastic epithelial cell growth and should be considered as potential serum markers of neoplastic prostate diseases.

Neutralizing VEGF bioactivity with a soluble chimeric VEGF-receptor protein flt(1-3)IgG inhibits testosterone-stimulated prostate growth in castrated mice

BACKGROUND

Recent studies show that testosterone-stimulated growth of the glandular tissue in the ventral prostate in adult castrated rats is preceded by increased epithelial VEGF synthesis, endothelial cell proliferation, vascular growth, and increased blood flow. These observations suggest that testosterone-stimulated prostate growth could be angiogenesis dependent, and that VEGF could play a central role in this process.

METHODS

Adult male mice were castrated and after 1 week treated with testosterone and vehicle, or with testosterone and a soluble chimeric VEGF-receptor flt(1-3)IgG protein.

RESULTS

Treatment with testosterone markedly increased endothelial cell proliferation, vascular volume, and organ weight in the ventral prostate lobe in the vehicle groups, but these responses were inhibited but not fully prevented by anti-VEGF treatment. The testosterone-stimulated increase in epithelial cell proliferation was unaffected by flt(1-3)IgG, but endothelial and epithelial cell apoptosis were increased in the anti-VEGF compared to the vehicle-treated groups.

CONCLUSIONS

This study suggests that testosterone stimulates vascular growth in the ventral prostate lobe indirectly by increasing epithelial VEGF synthesis and that this is a necessary component in testosterone-stimulated prostate growth.

Role of adrenocorticotropic hormone in the development and maintenance of the adrenal cortical vasculature

The adrenal cortex is a highly vascularized endocrine tissue. A dense network of blood capillaries centripetally irrigates the adrenal gland, allowing every endocrine cell to be in contact with an endothelial cell. The pituitary hormone ACTH controls the coordinated development of the vasculature and the endocrine tissue mass. This suggests that paracrine secretions between steroidogenic adrenocytes and capillary endothelial cells participate in the control of adrenocortical homeostasis. Besides its effect on the vascular tone of arteries, ACTH induces the expression of the angiogenic cytokine VEGF-A (vascular endothelial growth factor-A) in primary cultures of adrenocortical cells. This growth factor is a specific mitogen for endothelial cells and is likely to mediate the hormonal control of adrenocortical vascularization through a paracrine mechanism. The newly discovered angiogenic factor EG-VEGF (endocrine-gland-derived vascular endothelial growth factor), the expression of which is restricted to endocrine glands and which is preferentially mitogenic for endocrine tissue-derived endothelial cells, is another candidate mediator of great potential interest.

Endothelial cell proliferation in male reproductive organs of adult rat is high and regulated by testicular factors

Endothelial cells in the intact adult are, apart from those in the female reproductive organs, believed to be quiescent. Systematic examination of endothelial cell proliferation in male reproductive organs has not been performed and was therefore the aim of the present study. Intact adult rats were either pulse labeled or long-term labeled with bromodeoxyuridine to label proliferating cells. The roles of Leydig cells and testosterone were examined after castration or treatment with the Leydig cell toxin ethane dimethane sulfonate (EDS) and testosterone substitution. After perfusion fixation, all blood vessels remained open and were easily identified. In all male reproductive organs studied, particularly in the testis and epididymis, endothelial cell proliferation was considerably higher than in other tissues such as the liver, brain, and muscle. Proliferating endothelial cells were observed in all types of blood vessels in male reproductive organs, but other characteristics of new blood vessel formation were not seen. High endothelial cell proliferation may reflect a continuous high turnover of endothelial cells rather than classical angiogenesis. In the epididymis, the ventral and dorsolateral prostate lobes, and the seminal vesicles, endothelial cell proliferation decreased after testosterone withdrawal and increased following testosterone treatment. In the testis, endothelial cell proliferation was decreased after Leydig cell depletion but remained low after testosterone substitution. High, hormonally regulated endothelial cell proliferation is not unique to the female but is also seen in the male reproductive organs.

Intracavernosal vascular endothelial growth factor (VEGF) injection and adeno-associated virus-mediated VEGF gene therapy prevent and reverse venogenic erectile dysfunction in rats

Penile veno-occlusive dysfunction (venogenic erectile dysfunction) is a common cause of erectile dysfunction (ED). We investigated whether vascular endothelial growth factor (VEGF) can be used to prevent and reverse venogenic ED in a rat model. Pharmacological cavernosometry was developed and validated using adult male rats with either arteriogenic or venogenic ED. Castrated animals were treated with intracavernous VEGF as either a recombinant protein (C+VEGF) or adeno-associated virus (AAV)-mediated VEGF gene therapy (C+VEGF gene) in an attempt to prevent the development of venogenic ED. Other animal groups received testosterone replacement (C+testosterone) or intracavernous AAV-LacZ gene (C+LacZ). Animals with documented venogenic ED were treated with intracavernous VEGF in an attempt to reverse their ED. Functional analysis (pharmacological infusion cavernosometry) was performed following treatment. Penile specimens were harvested for immunohistochemistry and electron microscopic evaluation. Castrated rats showed a decrease in papaverine-induced intracavernous pressure and an increase in maintenance and drop rates during pharmacological cavernosometry. These changes were prevented by systemic testosterone and intracavernous VEGF or AAV-VEGF therapy. Moreover, intracavernous VEGF was able to reverse the venogenic ED produced by castration. The quantity of penile smooth muscle detected by alpha actin staining decreased after castration but not in the C+T, C+VEGF, or C+VEGF gene groups. Transmission electron microscopy revealed atrophy of penile smooth muscle cells and nerves in the castrated rats. In VEGF-treated rats, regeneration of smooth muscle and nerves as well as endothelial cell hypertrophy and hyperplasia were the prominent features. In our animal model, systemic testosterone replacement or intracavernous VEGF (protein and VEGF gene) prevented the veno-occlusive dysfunction in castrated animals. In rats with established venous leakage, VEGF treatment reversed the cavernosometric findings of leakage. Intracavernous injection of either VEGF protein or VEGF gene may be a preferred therapy to preserve erectile function in patients in whom testosterone therapy is contraindicated.

Prostate Development and Carcinogenesis

The process involved in the development and carcinogenesis of the prostate gland is complex. During early prostate development, the androgenic hormone from embryonic testicles is required for ductal formation, growth, and branching morphogenesis of the prostate gland. From this early stage, interactions between the epithelium and mesenchyme become firmly established through paracrine influence (i.e., growth factors) from mesenchyme (stroma), in response to testosterone, acting on epithelium to stimulate its proliferation, morphogenetic differentiation, and function. In return, the epithelium also exerts its paracrine effects on mesenchyme by regulating the differentiation and specific organizational pattern of its stromal smooth muscle. In a normal adult prostate, the maintenance of normal glandular structure and function is dependent not only on the constant presence of testosterone, but also on a normal intact and stable stroma. This chapter will concentrate first on factors involved in the normal development of the prostate gland and then on the aberrant changes in the homeostatic balance arising either from within (i.e., mutations) or outside (i.e., changes in hormonal balance) that result in derangements of the prostate gland. Finally, environmental and genetic factors that lead to prostate carcinogenesis including activation of oncogenes and mutations of tumor suppressor genes are also discussed.

Angiogenesis in prostate cancer: its role in disease progression and possible therapeutic approaches

The interaction between cancer cells and their microenvironment is a promising area for the development of novel therapeutic anti-cancer modalities. The formation of new blood vessels, angiogenesis, is an important step in cancer progression. Angiogenesis is a complex multistep process involving close orchestration of endothelial cells, extracellular matrix, and soluble factors. Essentially every step has been found to be regulated by inducers and inhibitors. Prostate cancer has the ability to produce angiogenic factors such as metalloproteinases, vascular endothelial growth factor, fibroblast growth factor 2, transforming growth factor-beta and cyclooxygenase-2. In several studies in prostate cancer an increased microvessel density is associated with poorer prognosis. On the other hand several endogenous inhibitors of angiogenesis have been described in prostate cancer e.g., angiostatin, endostatin, prostate specific antigen (PSA), thrombospondin-1, interleukin 10, interferons and retinoids. The expanding insight in the process of angiogenesis has resulted in a large number of pharmaceutical agents that have been tested in preclinical studies and are currently tested in clinical trials. These agents inhibit endothelial cell proliferation or migration and induce apoptosis. This ultimately will affect the formation of new vessels thereby inducing tumor dormancy. Because antiangiogenic treatment is cytostatic rather than cytotoxic, patients will need long-term therapy to prevent regrowth of the tumor. Prostate cancer is an ideal tumor for antiangiogenic studies because of the availability of a reliable tumor marker, PSA, the indolent clinical course of this cancer and the low rate of proliferation even in metastatic sites. Furthermore, clinical studies showed limited side effects, which is advantageous in this elderly patient group. Whether the ultimate antiangiogenic treatment is effective as a single agent or in combination with radiation therapy, chemotherapy or immunotherapy remains to be determined.

Endoglin (CD105) is expressed on immature blood vessels and is a marker for survival in prostate cancer

BACKGROUND

Endoglin, a receptor for some of the members of the transforming growth factor-beta (TGF-beta) family, is expressed on proliferating endothelial cells and has been suggested as a marker of ongoing angiogenesis. In this study, endoglin was evaluated as a prognostic factor for prostate cancer progression.

METHODS

Immunohistochemical staining of endoglin was examined in 72 cases of prostate cancer and compared with immunohistochemical staining of the pan-endothelial marker von Willebrand factor (vWf), clinicopathological factors, and cancer-specific survival. Micro-vessels were measured in the most vascularized fields. Double staining with antibodies against smooth muscle actin and endoglin or vWf, respectively, was performed in order to evaluate vessel maturation.

RESULTS

Endoglin-stained tumor vessels were generally small and only 19% also stained with actin. Endoglin was a better prognostic marker than vWf. The median survival times were shorter for patients with tumor vascular count (vc) above median than for patients with vc below median (4 vs. 12 years, P = 0.0007, and 5 vs. 10 years, P = 0.018, for endoglin and vWf, respectively). Endoglin vc was associated with Gleason score (P = 0.001), local tumor stage (P = 0.0006), metastasis (P = 0.01), tumor cell immunoreactivity for TGF-beta1 (P = 0.0003), and tumor cell proliferation index (r(s) = 0.319, P = 0.02). Endoglin, in contrast to vWf, vc was prognostic for survival in the subgroup of patients with Gleason score 5, 6, and 7 tumors.

CONCLUSIONS

Endoglin marks principally small, probably newly formed tumor vessels in zthe prostate, and is a promising prognostic marker for prostate cancer patients.

Androgens modulate the balance between VEGF and angiopoietin expression in prostate epithelial and smooth muscle cells

BACKGROUND

The vasculature of the prostate responds to androgens. Androgens most likely affect the vasculature indirectly by modulating the expression of angiogenic factors in the cells of the prostate. Most studies to date have examined the production of angiogenic factors by the prostate luminal epithelium. Here we examine the effects of androgen on production of three angiogenic factors, vascular endothelial growth factor (VEGF), angiopoietin-1, and angiopoietin-2, by the three major cell types in the prostate.

METHODS

The ability of androgen to modulate VEGF, angiopoietin-1, and angiopoietin-2 production in cultured mouse prostate luminal epithelial, basal epithelial, and smooth muscle cells (SMCs) was assessed by Western blot and RT-PCR.

RESULTS

The production of VEGF was modulated by androgens in both luminal epithelial and prostate SMCs but not in basal epithelial cells. However, in prostate luminal epithelial cell cultures, VEGF was predominately secreted apically, suggesting that in vivo most of the epithelium-derived VEGF is unavailable to the underlying blood vessels. In addition, prostate luminal epithelial cells produced angiopoietin-2, an angiogenesis inhibitor. In contrast, prostate SMCs produced angiopoietin-1, a positive modulator of angiogenesis. Synthesis of the angiopoietins did not respond to androgen treatment.

CONCLUSIONS

Prostate smooth muscle may play an important role in regulating vascular responses to androgen.

Reactive stroma in prostate cancer progression

PURPOSE

The development of an altered stromal microenvironment in response to carcinoma is a common feature of many tumors. We reviewed the literature describing characteristics of reactive stroma, how reactive stroma affects cancer progression and how carcinoma regulates reactive stroma. Moreover, we present a hypothesis of reactive stroma in prostate cancer and discuss how the biology of reactive stroma may be used in novel diagnostic and therapeutic approaches.

MATERIALS AND METHODS

An extensive literature search was performed to review reports of the general features of wound repair stroma, general stromal responses to carcinoma, and stromal biology of normal and prostate cancer tissues. These studies were analyzed and a reactive stroma hypothesis in prostate cancer was developed.

RESULTS

Modifications to the stroma of breast, colon and prostate tumors parallel the generation of granulation tissue in wound repair. These changes include stromal cell phenotypic switching, extracellular matrix remodeling and angiogenesis induction. Therefore, it is predicted that a modified wound healing response induces the formation of reactive stroma in cancer to create a tumor promoting environment. Based on its role in wound repair and its over expression in prostate cancer, transforming growth factor-beta stands out as a potential regulator of reactive stroma.

CONCLUSIONS

Reactive stroma in prostate cancer and granulation tissue in wound repair show similar biological responses and processes that are predicted to promote cancer progression. Further identification of specific functional and regulatory mechanisms in prostate cancer reactive stroma may aid in the use of reactive stroma for novel diagnostic and therapeutic approaches.

Thrombospondin-1, vascular endothelial growth factor and fibroblast growth factor-2 are key functional regulators of angiogenesis in the prostate

BACKGROUND

Prostate cells secrete many molecules capable of regulating angiogenesis; however, which of these actually function as essential regulators of neovascularization is not yet clear.

METHODS

Functional angiogenic mediators secreted by normal and diseased prostate cells were identified using an in vitro angiogenesis assay. These factors were quantified by immunoblot or ELISA and localized in tissue by immunohistochemistry.

RESULTS

Normal prostate epithelial cell secretions were anti-angiogenic due to inhibitory thrombospondin-1 (TSP-1) whereas this inhibitor was decreased in the pro-angiogenic secretions derived from benign prostatic hyperplasia (BPH) and cancer cells. This pro-angiogenic activity depended primarily on fibroblast growth factor-2 (FGF-2) and/or vascular endothelial growth factor (VEGF) whose secretion was increased. Immunolocalization studies confirmed that the changes detected in vitro also occurred in vivo.

CONCLUSIONS

During disease progression in the prostate, production of TSP-1, the major inhibitor, is down-regulated while that of stimulatory FGF-2 and/or VEGF rise, leading to the induction of the new vessels necessary to support tumor growth.

Blood loss during transurethral resection of the prostate after 3 months of treatment with finasteride

OBJECTIVES

To study whether pretreatment with finasteride, compared with placebo, reduces the blood loss, operating time, amount of irrigating fluid absorbed, resources used, and other exploratory indexes of extensive surgery during transurethral resection of the prostate (TURP).

METHODS

This double-blind, randomized, placebo-controlled, single-center, 6-month pilot study was designed to study the effects of 3 months of finasteride (5 mg daily) on blood loss during surgery in 60 men who required TURP. The prostate size was measured by transrectal ultrasonography, the surgical blood loss was measured by a HemoCue photometer, and fluid absorption was determined by the ethanol method. The microvessel density was counted using microscopic staining and immunoperoxidase techniques.

RESULTS

Finasteride significantly reduced the prostate size before TURP (P <0.001 versus placebo). No significant between-group differences were found in blood loss (geometric mean 257 and 268 mL for finasteride versus placebo), fluid absorption, operating time, resection weight, or microvessel density. A positive correlation was found between the blood loss and the resection weight. Exploratory analyses indicated that finasteride might reduce the proportion of patients with high blood loss volumes. For prostates with resection weights greater than or equal to the median (18.6 g), finasteride was associated with less blood loss (median 324 mL, n = 14) than in the controls (median 547 mL, n = 14, P <0.01).

CONCLUSIONS

Pretreatment with finasteride may help reduce the blood loss in TURP, except in the smallest resections.