Androgens induce the expression of vascular endothelial growth factor in human fetal prostatic fibroblasts

Development of a novel prostate Cancer-Stroma Sphere (CSS) model for In Vitro tumor microenvironment studies

Tumor employs non-cancerous cells to gain beneficial features that promote growth and survival of cancer cells. Despite intensive research in the area of tumor microenvironment, there is still a lack of reliable and reproducible in vitro model for tumor and tumor-microenvironment cell interaction studies. Herein we report the successful development of a heterogeneous cancer-stroma sphere (CSS) model composed of prostate adenocarcinoma PC3 cells and immortalized mesenchymal stem cells (MSC). The CSS model demonstrated a structured spatial layout of the cells, with stromal cells concentrated at the center of the spheres and tumor cells located on the periphery. Significant increase in the levels of VEGFA, IL-10, and IL1a has been detected in the conditioned media of CSS as compared to PC3 spheres. Single cell RNA sequencing data revealed that VEGFA was secreted by MSC cells within heterogeneous spheroids. Enhanced expression of extracellular membrane (ECM) proteins was also shown for CSS-derived MSCs. Furthermore, we demonstrated that the multicellular architecture altered cancer cell response to chemotherapeutic agents: the inhibition of sphere formation by topotecan was 74.92 ± 4.56 % for PC3 spheres and 45.95 ± 7.84 % for CSS spheres (p < 0.01), docetaxel showed 37,51± 20,88 % and 15,67± 14,08 % inhibition, respectively (p < 0.05). Thus, CSS present an effective in vitro model for examining the extracellular matrix composition and cell-to-cell interactions within the tumor, as well as for evaluating the antitumor activity of drugs.

Evaluation of the Antioxidant and Antiangiogenic Activity of a Pomegranate Extract in BPH-1 Prostate Epithelial Cells

Benign prostatic hypertrophy (BPH) is a noncancerous enlargement of the prostate gland that develops from hyper-proliferation of the stromal and epithelium region. Activation of pathways involving inflammation and oxidative stress can contribute to cell proliferation in BPH and tumorigenesis. Agricultural-waste-derived extracts have drawn the attention of researchers as they represent a valid and sustainable way to exploit waste production. Indeed, such extracts are rich in bioactive compounds and can provide health-promoting effects. In particular, extracts obtained from pomegranate wastes and by-products have been shown to exert antioxidant and anti-inflammatory effects. This study focused on the evaluation of the anti-angiogenic effects and chemopreventive action of a pomegranate extract (PWE) in cellular models of BPH. In our experimental conditions, we observed that PWE was able to significantly (p < 0.001) reduce the proliferation and migration rates (up to 60%), together with the clonogenic capacity of BPH-1 cells concomitantly with the reduction in inflammatory cytokines (e.g., IL-6, PGE2) and pro-angiogenic factor (VEGF-ADMA) release. Additionally, we demonstrated the ability of PWE in reducing angiogenesis in an in vitro model of BPH consisting in transferring BPH-1-cell-conditioned media to human endothelial H5V cells. Indeed, PWE was able to reduce tube formation in H5V cells through VEGF level reduction even at low concentrations. Overall, we confirmed that inhibition of angiogenesis may be an alternative therapeutic option to prevent neovascularization in prostate tissue with BPH and its transformation into malignant prostate cancer.

Androgens promote vascular endothelial cell proliferation through activation of a ZIP9-dependent inhibitory G protein/PI3K-Akt/Erk/cyclin D1 pathway

While androgens have been reported to mediate cardiovascular endothelial cell proliferation, the potential involvement of membrane androgen receptors (mAR) has not been examined. Here we show ZIP9, a recently characterized mAR, mediates androgen-induced early proliferative events in human umbilical vein endothelial cells (HUVECs). Androgen treatment significantly increased cyclin D1 nuclear localization and proliferation, which were blocked by transfection with siRNA targeting ZIP9 but not the nuclear AR. Testosterone rapidly activated inhibitory G protein signaling, Erk, and Akt, and inhibition of these signaling members abrogated the ZIP9-mediated cyclin D1 and proliferative responses. Erk and Akt modulated cyclin D1 nuclear localization by upregulation of cyclin D1 mRNA and inhibition of GSK-3β activity, respectively. This is the first study to demonstrate a role for ZIP9 in HUVEC proliferation and indicates ZIP9 is a physiologically-relevant androgen receptor in the cardiovascular system that merits further study as a potential therapeutic target for treating cardiovascular disease.

Activation of GPR56, a novel adhesion GPCR, is necessary for nuclear androgen receptor signaling in prostate cells

The androgen receptor (AR) is activated in patients with castration resistant prostate cancer (CRPC) despite low circulating levels of androgen, suggesting that intracellular signaling pathways and non-androgenic factors may contribute to AR activation. Many G-protein coupled receptors (GPCR) and their ligands are also activated in these cells indicating that they may play a role in development of Prostate Cancer (PCa) and CRPC. Although a cross talk has been suggested between the two pathways, yet, the identity of GPCRs which may play a role in androgen signaling, is not established yet. By using blast analysis of 826 GPCRs, we identified a GPCR, GPCR 205, which exhibited maximum similarity with the ligand binding domain of the AR. We demonstrate that adhesion GPCR 205, also known as GPR56, can be activated by androgens to stimulate the Rho signaling pathway, a pathway that plays an important role in prostate tumor cell metastasis. Testosterone stimulation of GPR56 also activates the cAMP/ Protein kinase A (PKA) pathway, that is necessary for AR signaling. Knocking down the expression of GPR56 using siRNA, disrupts nuclear translocation of AR and transcription of prototypic AR target genes such as PSA. GPR56 expression is higher in all twenty-five prostate tumor patient’s samples tested and cells expressing GPR56 exhibit increased proliferation. These findings provide new insights about androgen signaling and identify GPR56 as a possible therapeutic target in advanced prostate cancer patients.

6-sialyllactose ameliorates dihydrotestosterone-induced benign prostatic hyperplasia through suppressing VEGF-mediated angiogenesis

Benign prostatic hyperplasia (BPH), a common disease in elderly males, is accompanied by non-malignant growth of prostate tissues, subsequently causing hypoxia and angiogenesis. Although VEGF-related angiogenesis is one of the therapeutic targets of prostate cancer, there is no previous study targeting angiogenesis for treatment of BPH. Dihydrotestosterone (DHT)-induced expressions of vascular endothelial growth factor (VEGF) in prostate epithelial RWPE-1 cells and human umbilical vascular endothelial cells (HUVECs). Conditioned media (CM) from DHT-treated RWPE-1 cells were transferred to HUVECs. Then, 6SL inhibited proliferation, VEGFR-2 activation, and tube formation of HUVECs transferred with CM from DHT-treated RWPE-1 cells. In the rat BPH model, 6SL reduced prostate weight, size, and thickness of the prostate tissue. Formation of vessels in prostatic tissues were also reduced with 6SL treatment. We found that 6SL has an ameliorative effect on in vitro and in vivo the BPH model via inhibition of VEGFR-2 activation and subsequent angiogenesis. These results suggest that 6SL might be a candidate for development of novel BPH drugs.

ZBTB46, SPDEF, and ETV6: Novel Potential Biomarkers and Therapeutic Targets in Castration-Resistant Prostate Cancer

Prostate cancer (PCa) is the second most common killer among men in Western countries. Targeting androgen receptor (AR) signaling by androgen deprivation therapy (ADT) is the current therapeutic regime for patients newly diagnosed with metastatic PCa. However, most patients relapse and become resistant to ADT, leading to metastatic castration-resistant PCa (CRPC) and eventually death. Several proposed mechanisms have been proposed for CRPC; however, the exact mechanism through which CRPC develops is still unclear. One possible pathway is that the AR remains active in CRPC cases. Therefore, understanding AR signaling networks as primary PCa changes into metastatic CRPC is key to developing future biomarkers and therapeutic strategies for PCa and CRPC. In the current review, we focused on three novel biomarkers (ZBTB46, SPDEF, and ETV6) that were demonstrated to play critical roles in CRPC progression, epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) drug resistance, and the epithelial-to-mesenchymal transition (EMT) for patients treated with ADT or AR inhibition. In addition, we summarize how these potential biomarkers can be used in the clinic for diagnosis and as therapeutic targets of PCa.

Triiodothyronine stimulates VEGF expression and secretion via steroids and HIF-1α in murine Leydig cells

Leydig cells are the principal steroidogenic cells of the testis. Leydig cells also secrete a number of growth factors including vascular endothelial growth factor (VEGF) which has been shown to regulate both testicular steroidogenesis and spermatogenesis. The thyroid hormone, T_3, is known to stimulate steroidogenesis in Leydig cells. T₃ has also been shown to stimulate VEGF production in a variety of cell lines. However, studies regarding the effect of T₃ on VEGF synthesis and secretion by the Leydig cells were lacking. Therefore, we investigated the effect of T₃ on VEGF synthesis and secretion in a mouse Leydig tumour cell line, MLTC-1. The effect of T₃ was compared with that of LH/cAMP and hypoxia, two known stimulators of Leydig cell functions. The cells were treated with T₃, 8-Br-cAMP (a cAMP analogue), or CoCl₂ (a hypoxia mimetic) and VEGF secreted in the cell supernatant was measured using ELISA. The mRNA levels of VEGF were measured by quantitative RT-PCR. In the MLTC-1 cells, T₃, 8-Br-cAMP, and CoCl₂ stimulated VEGF mRNA levels and the protein secretion. T₃ also increased steroid secretion as well as HIF-1α protein levels, two well-established upstream regulators of VEGF. Inhibitors of steroidogenesis as well as HIF-1α resulted in inhibition of T₃-stimulated VEGF secretion by the MLTC-1 cells. This suggested a mediatory role of steroids and HIF-1α protein in T₃-stimulated VEGF secretion by MLTC-1 cells. The mediation by steroids and HIF-1α were independent of each other.

ABBREVIATIONS

8-Br-cAMP: 8-bromo - 3', 5' cyclic adenosine monophosphate; CoCl₂: cobalt chloride; HIF-1α: hypoxia inducible factor -1α; LH: luteinizing hormone; T₃: 3, 5, 3'-L-triiodothyronine; VEGF: vascular endothelial growth factor.

Androgen Deprivation Therapy for Prostate Cancer

In the contemporary scene, less than 5% of men with newly diagnosed prostate cancer (PC) have metastases at first presentation, compared to 20-25%, more than 20 years ago. Nonetheless, the use of androgen deprivation therapy (ADT) has increased over the years, suggesting that patients in Europe and United States may receive ADT in cases of lower disease burden, and not always according to evidence based indications. Nonetheless, PC remains the second most common cause of cancer death after lung cancer in American men. Thus, there is a need for more effective, specific and well tolerated agents which can provide a longer and good quality of life while avoiding the side effects related to disease and treatment morbidity.After mentioning the current knowledge on the endocrinology of androgens and androgen receptor, relevant to PC development, as well as the possible events occurring during PC initiation, we will compare different hormonal compounds available for the treatment of PC, both from a pharmacological standpoint, and in terms of contemporary clinical indications.

Crosstalk between the Androgen Receptor and PPAR Gamma Signaling Pathways in the Prostate

Nuclear receptors are a superfamily of ligand-activated transcription factors that play critical roles in the regulation of normal biological processes and several disease states. Of the nuclear receptors expressed within the prostate, the androgen receptor (AR) promotes the differentiation of prostatic epithelial cells and stimulates production of enzymes needed for liquefaction of semen. Multiple forms of AR also promote the growth of both early and late stage prostate cancers. As a result, drugs that target the AR signaling pathway are routinely used to treat patients with advanced forms of prostate cancer. Data also suggest that a second member of the nuclear receptor superfamily, the peroxisome proliferator activated receptor gamma (PPARγ), is a tumor suppressor that regulates growth of normal prostate and prostate cancers. Recent studies indicate there is a bidirectional interaction between AR and PPARγ, with each receptor influencing the expression and/or activity of the other within prostatic tissues. In this review, we examine how AR and PPARγ each regulate the growth and development of normal prostatic epithelial cells and prostate cancers. We also discuss interactions between the AR and PPARγ signaling pathways and how those interactions may influence prostate biology.

Is There a Role for Preoperative 5 Alpha Reductase Inhibitors in Reducing Prostate Vascularity and Blood Loss?

Benign prostatic hyperplasia (BPH) and the related medical problems are a major burden as health care costs and as a cause of patient morbidity. The introduction of medical therapy largely offered an alternative to surgical therapy, and these medications have been linked with multiple positive BPH-related outcomes. With ubiquitous use, however, a variety of adverse side effects and unsupported claims to these medications have been reported both in scientific literature and popular press. The use of 5 alpha reductase inhibitors (5ARIs) to reduce recurrent bleeding due to BPH is a reasonable option for men with recurrent trips to the physician or hospital. After a largely anecdotal report of their use in the preoperative period to reduce bleeding during BPH surgery, there was interest in the use of 5ARIs for this indication considering the effusive bleeding that can occur during BPH-related surgery, a dreaded and not uncommon complication. While the pathophysiology for the use of 5ARI to reduce BPH-related bleeding is sound, the actual clinical outcomes still require scrutiny to determine if the efficacy is both scientifically valid and clinically significant. This report will review the current literature on this topic and make attempts to determine if the use of a 5ARI before BPH-related surgery should be encouraged.

The Androgen Receptor and VEGF: Mechanisms of Androgen-Regulated Angiogenesis in Prostate Cancer

Prostate cancer progression is controlled by the androgen receptor and new blood vessel formation, or angiogenesis, which promotes metastatic prostate cancer growth. Angiogenesis is induced by elevated expression of vascular endothelial growth factor (VEGF). VEGF is regulated by many factors in the tumor microenvironment including lowered oxygen levels and elevated androgens. Here we review evidence delineating hormone mediated mechanisms of VEGF regulation, including novel interactions between the androgen receptor (AR), epigenetic and zinc-finger transcription factors, AR variants and the hypoxia factor, HIF-1. The relevance of describing the impact of both hormones and hypoxia on VEGF expression and angiogenesis is revealed in recent reports of clinical therapies targeting both VEGF and AR signaling pathways. A better understanding of the complexities of VEGF expression could lead to improved targeting and increased survival time for a subset of patients with metastatic castration-resistant prostate cancer.

Prostatic Artery Embolization (PAE) for Symptomatic Benign Prostatic Hyperplasia (BPH): Part 1, Pathological Background and Clinical Implications

Pathological features of benign prostatic hyperplasia (BPH) dictate various responses to prostatic artery embolization (PAE). Typically, BPH originates in the transition zone and periurethral region, where should be considered the primary target area in PAE procedures. Given that histological heterogeneity of components in hyperplasia nodules, epithelial or stromal, identifying the more responsive nodules to PAE will have clinical implications. Since some lower urinary tract symptoms (LUTS) in patients with BPH are usually related to bladder outlet obstruction-induced changes in bladder function rather than to outflow obstruction directly, proper selection of candidate patients prior to PAE is of great clinical importance. BPH is a typical chronic progressive condition, suggesting PAE could aim not only to relieve LUTS but also to delay or prevent the clinical progression. Awareness of the pathological background of BPH is essential for interventional radiologists to improve clinical outcomes and develop new treatment strategies in clinical practice of PAE.

A herbal formula, comprising Panax ginseng and bee-pollen, inhibits development of testosterone-induced benign prostatic hyperplasia in male Wistar rats

A recent study reported that Panax ginseng (P. ginseng) has a protective effect on the development of benign prostatic hyperplasia (BPH). KH053 is used as a new herbal prescription consisting of P. ginseng and bee-pollen. The present study aimed to investigate whether the KH053 has inhibition effects on the development of benign prostatic hyperplasia (BPH) using an animal model with testosterone induced BPH. The experiment was carried out in forty male Wistar 7 week old rats that were divided into four groups (control group, BPH group, positive group, and KH053 group). One group was used as the control and the three groups received subcutaneous injections of testosterone 20 mg/kg for 4 weeks to induce BPH. One of them received KH053 by oral gavage daily at doses of 200 mg/kg concurrently with the testosterone. The positive group received finasteride at a dose of 1 mg/kg with testosterone. After 4 weeks, all rats were sacrificed and analyzed for prostate weight, and growth factors. Results revealed that, compared to rats in the BPH group, KH053 showed that the prostate weight and dihydrotestosterone (DHT) levels in serum were significantly decreased and the decreases in hyperplasia in prostate were also observed. In addition, immunohistochemistry (IHC) also revealed that the protein expressions of growth factors [transforming growth factor β1 (TGF-β1) and vascular endothelial growth factor (VEGF)] in prostate tissue were decreased in the KH053 group. In conclusion, these results suggest that KH053, comprising P. ginseng and bee-pollen, inhibits the development of BPH in Wistar rat model and might be used as functional food for BPH.

Perioperative use of cyproterone acetate with transurethral resection of large prostate: preliminary results

PURPOSE

To assess the impact of short-term treatment with cyproterone acetate (CPA) on intraoperative and early postoperative complications of transurethral resection of relatively large prostate.

PATIENTS AND METHODS

We recruited patients with prostate size of 60-90 g and randomized them into two equal groups. The first one had 50 mg of CPA orally twice a day (bds) for 2 weeks before the operation and maintained it for an extra week postoperatively. The other group received placebo. All patients underwent monopolar transurethral prostatectomy (M-TURP) and the prostatic chips were stained for CD34 specific for nascent blood vessels.

RESULTS

Ninety-five patients were included. Mean patient age was 60.88±2.5 years and mean prostate size was 72.76±7.21 g. CPA was well tolerated with no serious adverse effects. The mean resection time and the mean weight of the resected tissue were comparable between the two groups. Intraoperative blood loss, fluid absorption, and blood loss per gram of resected tissue (259.47±78.27 mL, 787.38±300.56 mL, and 14.87±4.02 mL/g and 327.25±98.97 mL, 937.4±350.2 mL, and 17.08±5.55 mL/g, respectively) were significantly lower in the treatment group (p<0.05). In addition, excessive postoperative bleeding was encountered in one case in the treatment group and in seven in the control (p<0.05). Finally, the histopathological study revealed that the mean microvessel density in each of the suburethral portion and the hyperplastic nodules of the prostate was significantly lower in the CPA group (p<0.001).

CONCLUSION

The perioperative use of CPA with M-TURP of a relatively large prostate may help in decreasing the perioperative bleeding and fluid absorption that usually take place during this procedure.

Stromal androgen receptor roles in the development of normal prostate, benign prostate hyperplasia, and prostate cancer

The prostate is an androgen-sensitive organ that needs proper androgen/androgen receptor (AR) signals for normal development. The progression of prostate diseases, including benign prostate hyperplasia (BPH) and prostate cancer (PCa), also needs proper androgen/AR signals. Tissue recombination studies report that stromal, but not epithelial, AR plays more critical roles via the mesenchymal-epithelial interactions to influence the early process of prostate development. However, in BPH and PCa, much more attention has been focused on epithelial AR roles. However, accumulating evidence indicates that stromal AR is also irreplaceable and plays critical roles in prostate disease progression. Herein, we summarize the roles of stromal AR in the development of normal prostate, BPH, and PCa, with evidence from the recent results of in vitro cell line studies, tissue recombination experiments, and AR knockout animal models. Current evidence suggests that stromal AR may play positive roles to promote BPH and PCa progression, and targeting stromal AR selectively with AR degradation enhancer, ASC-J9, may allow development of better therapies with fewer adverse effects to battle BPH and PCa.

Aging impairs VEGF-mediated, androgen-dependent regulation of angiogenesis

There is a progressive impairment of vascular repair mechanisms with advancing age concomitant with a steady decline in circulating androgen levels in men. Emerging evidence indicates androgens regulate angiogenesis; however, little research has focused on the impact of age upon androgen-mediated regulation of angiogenic mechanisms. Human dermal fibroblasts from young (<30 years) and older (>65 years) men were incubated with DHT, with or without androgen receptor antagonist hydroxyflutamide, or phosphoinositide 3-kinase inhibitor. Fibroblast-conditioned medium was used to stimulate angiogenic functions in human umbilical vein endothelial cells. Nuclear fractionation and fluorescence microscopy were used to study androgen receptor (AR) distribution. Conditioned medium from fibroblasts of young men, but not old men, treated with DHT produced a 3-fold increase in human umbilical vein endothelial cell tubulogenesis and 2-fold increase in migration via increased vascular endothelial growth factor (VEGF) expression and secretion, predominantly of VEGF145. DHT-induced VEGF secretion from fibroblasts of young men was AR-dependent and increased AKT phosphorylation, which was abrogated by phosphoinositide 3-kinase inhibition. By contrast, fibroblasts from older men were unresponsive to DHT and lacked androgen-mediated enhancement in VEGF production. These findings were associated with reduced AR nuclear translocation in old fibroblasts. The failure of DHT-induced paracrine stimulation of angiogenesis in fibroblasts from older men is likely due to defective nuclear translocation of AR. This first demonstration of androgen resistance (or insensitivity) acquired by human fibroblasts with aging suggests that pharmacological testosterone therapy for old men may be less effective in enhancing angiogenesis and facilitating tissue regeneration mechanisms reliant on paracrine release of VEGF.

Targeting the relaxin hormonal pathway in prostate cancer

Targeting the androgen signalling pathway has long been the hallmark of anti-hormonal therapy for prostate cancer. However, development of androgen-independent prostate cancer is an inevitable outcome to therapies targeting this pathway, in part, owing to the shift from cancer dependence on androgen signalling for growth in favor of augmentation of other cellular pathways that provide proliferation-, survival- and angiogenesis-promoting signals. This review focuses on the role of the hormone relaxin in the development and progression of prostate cancer, prior to and after the onset of androgen independence, as well as its role in cancers of other reproductive tissues. As the body of literature expands, examining relaxin expression in cancerous tissues and its role in a growing number of in vitro and in vivo cancer models, our understanding of the important involvement of this hormone in cancer biology is becoming clearer. Specifically, the pleiotropic functions of relaxin affecting cell growth, angiogenesis, blood flow, cell migration and extracellular matrix remodeling are examined in the context of cancer progression. The interactions and intercepts of the intracellular signalling pathways of relaxin with the androgen pathway are explored in the context of progression of castration-resistant and androgen-independent prostate cancers. We provide an overview of current anti-hormonal therapeutic treatment options for prostate cancer and delve into therapeutic approaches and development of agents aimed at specifically antagonizing relaxin signalling to curb tumor growth. We also discuss the rationale and challenges utilizing such agents as novel anti-hormonals in the clinic, and their potential to supplement current therapeutic modalities.

Evolving treatment paradigms for locally advanced and metastatic prostate cancer

While men with early stage prostate cancer typically enjoy long-term survival after definitive management, for those who present with locally advanced or metastatic disease, survival is compromised. Multimodality therapy can prolong survival in these patients, with state-of-the-art options including intensity-modulated radiation or brachytherapy in conjunction with androgen ablation, adjuvant androgen ablation and/or chemotherapy with radical retropubic prostatectomy. In addition, novel biological therapies are being explored to target the unique molecular changes in prostate cancer cells and their interactions with the microenvironment. With these advances the outlook will undoubtedly improve, even for patients presenting with advanced disease. Careful application of these emerging therapies to a select group of prostate cancer patients most likely to obtain benefit from them is the challenge for urologists, medical oncologists and radiation oncologists for the future.

The role of vascular endothelial growth factor in metastatic prostate cancer to the skeleton

Despite the clinical implication and high incidence of bone and spinal metastases, the molecular mechanisms behind prostate cancer metastasis to bone and spine are not well understood. In this review the molecular mechanisms that may contribute to the highly metastatic phenotype of prostate cancer are discussed. Proangiogenic factors such as vascular endothelial growth factor (VEGF) have been shown to not only aid in the metastatic capabilities of prostate cancer but also encourage the colonization and growth of prostate tumour cells in the skeleton. The importance of VEGF in the complex process of prostate cancer dissemination to the skeleton is discussed, including its role in the development of the bone premetastatic niche, metastatic tumour cell recognition of bone, and bone remodeling. The expression of VEGF has also been shown to be upregulated in prostate cancer and is associated with clinical stage, Gleason score, tumour stage, progression, metastasis, and survival. Due to the multifaceted effect VEGF has on tumour angiogenesis, tumour cell proliferation, and bone destruction, therapies targeting the VEGF pathways have shown promising clinical application and are being investigated in clinical trials.

Involvement of androgens in ovarian health and disease

In women, ovary and adrenal gland produce androgens. Androgens are essential drivers of the primordial to antral follicle development, prior to serving as substrate for estrogen production in the later stages of folliculogenesis. Androgens play a crucial role in the follicular-stromal intertalk by fine tuning the extracellular matrix and vessel content of the ovarian stroma. Local auto-and paracrine factors regulate androgen synthesis in the pre-antral follicle. Androgen excess is a hallmark of polycystic ovary syndrome and is a key contributor in the exaggerated antral follicle formation, stromal hyperplasia and hypervascularity. Hyperandrogenaemia overrides the follicular-stromal dialog, resulting in follicular arrest and disturbed ovulation. On the other hand, androgen deficiency is likely to have a negative impact on fertility as well, and further research is needed to examine the benefits of androgen-replacement therapy in subfertility.

Androgen up-regulates vascular endothelial growth factor expression in prostate cancer cells via an Sp1 binding site

Background

Vascular Endothelial Growth Factor (VEGF) is regulated by a number of different factors, but the mechanism(s) behind androgen-mediated regulation of VEGF in prostate cancer are poorly understood.

Results

Three novel androgen receptor (AR) binding sites were discovered in the VEGF promoter and in vivo binding of AR to these sites was demonstrated by chromatin immunoprecipitation. Mutation of these sites attenuated activation of the VEGF promoter by the androgen analog, R1881 in prostate cancer cells. The transcription factors AR and Sp1 were shown to form a nuclear complex and both bound the VEGF core promoter in chromatin of hormone treated CWR22Rv1 prostate cancer cells. The importance of the Sp1 binding site in hormone mediated activation of VEGF expression was demonstrated by site directed mutagenesis. Mutation of a critical Sp1 binding site (Sp1.4) in the VEGF core promoter region prevented activation by androgen. Similarly, suppression of Sp1 binding by Mithramycin A treatment significantly reduced VEGF expression.

Conclusions

Our mechanistic study of androgen mediated induction of VEGF expression in prostate cancer cells revealed for the first time that this induction is mediated through the core promoter region and is dependent upon a critical Sp1 binding site. The importance of Sp1 binding suggests that therapy targeting the AR-Sp1 complex may dampen VEGF induced angiogenesis and, thereby, block prostate cancer progression, helping to maintain the indolent form of prostate cancer.

Gonadotropin-Mediated Regulation of the Murine VEGF Expression in MA-10 Leydig Cells

Presence of vascular endothelial growth factor (VEGF) is not only limited to cells directly involved in angiogenesis but has also been demonstrated in steroidogenic cells like testicular Leydig cells. Because Leydig cells are subjected to regulation by gonadotropic hormones and produce steroid hormones, we have investigated here the effects of human chorionic gonadotropin (hCG) or steroid hormones on VEGF expression in cultured mouse tumor Leydig cells (MA-10 cells) and have then analyzed the underlying molecular mechanisms. Northern blot analysis and enzyme-linked immunosorbent assays revealed increases in VEGF mRNA and protein levels, respectively, over 3-20 hours in MA-10 cells after stimulation with hCG or 8-Br-cAMP. Although MA-10 cells lack the classical progesterone receptor, progesterone was able to stimulate VEGF expression. Promoter analyses and antibody supershift experiments suggested that the proximal region is able to constitutively bind the transcription factors Sp1 and Sp3. Mutations of 2 potential Sp1 binding sites in the proximal region showed the requirement of these motifs for stimulation of VEGF by hCG and 8-Br-cAMP. The distal cytosine-rich sequence interacts with so far-unidentified faster migrating factors. Following stimulation with hCG or 8-Br-cAMP, the binding of these proteins was increased in the complexes formed in the proximal and distal regions. VEGF expression in Leydig cells is regulated by gonadotropin via a cAMP-dependent mechanism, and the transcription factors Sp1 and Sp3 appear to be involved in the activation of the promoter. Progesterone also appears to play a role in the regulation of VEGF, acting presumably via a nonconventional receptor that remains to be characterized yet.

Dose-related estrogen effects on gene expression in fetal mouse prostate mesenchymal cells

Developmental exposure of mouse fetuses to estrogens results in dose-dependent permanent effects on prostate morphology and function. Fetal prostatic mesenchyme cells express estrogen receptor alpha (ERα) and androgen receptors and convert stimuli from circulating estrogens and androgens into paracrine signaling to regulate epithelial cell proliferation and differentiation. To obtain mechanistic insight into the role of different doses of estradiol (E2) in regulating mesenchymal cells, we examined E2-induced transcriptomal changes in primary cultures of fetal mouse prostate mesenchymal cells. Urogenital sinus mesenchyme cells were obtained from male mouse fetuses at gestation day 17 and exposed to 10 pM, 100 pM or 100 nM E2 in the presence of a physiological concentration of dihydrotestosterone (0.69 nM) for four days. Gene ontology studies suggested that low doses of E2 (10 pM and 100 pM) induce genes involved in morphological tissue development and sterol biosynthesis but suppress genes involved in growth factor signaling. Genes involved in cell adhesion were enriched among both up-regulated and down-regulated genes. Genes showing inverted-U-shape dose responses (enhanced by E2 at 10 pM E2 but suppressed at 100 pM) were enriched in the glycolytic pathway. At the highest dose (100 nM), E2 induced genes enriched for cell adhesion, steroid hormone signaling and metabolism, cytokines and their receptors, cell-to-cell communication, Wnt signaling, and TGF- β signaling. These results suggest that prostate mesenchymal cells may regulate epithelial cells through direct cell contacts when estrogen level is low whereas secreted growth factors and cytokines might play significant roles when estrogen level is high.

The differential effects of prostate stromal cells derived from different zones on prostate cancer epithelial cells under the action of sex hormones

It is well known that prostate cancer (PCa) occurs predominantly in the peripheral zone (PZ), whereas benign prostatic hyperplasia (BPH) typically develops in the transition zone. To identify possible mechanisms underlying zonal differences, we compared the effects of prostate stromal cells derived from the peripheral zone (PZsc) and the transition zone (TZsc) on a PCa epithelial cell line (PC3) in the presence of sex hormones. First, we observed that androgen receptor (AR) mRNA was more highly expressed in PZsc than TZsc when the cells were treated with dihydrotestosterone (DHT) and β-oestradiol (E2) (P<0.05). By ELISA, we looked for differences in the secretion of peptide growth factors from PZsc and TZsc. We found that keratinocyte growth factor (KGF) secretion increased with increasing concentrations of DHT (P<0.01) and was higher in PZsc than TZsc. Under treatment with DHT plus E2, PZsc secreted more transforming growth factor-β1 (TGF-β1) than TZsc, but this pattern was reversed when the cells were treated with E2 only. With increasing concentrations of DHT, insulin-like growth factor-1 (IGF-1) secretion increased in PZsc but decreased in TZsc. To further characterize the effects of PZsc and TZsc on PC3 cells, we developed a coculture model and performed MTT assays, Western blot analysis and real-time RT-PCR. We found that PZsc promoted PC3 cell proliferation and progression better than TZsc, particularly when treated with 10 nmol l(-1) DHT plus 10 nmol l(-1) E2. In conclusion, our data suggest that PZsc may have a greater capacity to induce PCa development and progression than TZsc via growth factors regulated by sex hormones. These findings provide possible mechanisms underlying zonal differences in prostate diseases, which may aid the search for novel therapeutic targets for PCa.

Persistent, biologically meaningful prostate cancer after 1 year of androgen ablation and docetaxel treatment

PURPOSE

Clinicians are increasingly willing to treat prostate cancer within the primary site in the presence of regional lymph node or even limited distant metastases. However, no formal study on the merits of this approach has been reported. We used a preoperative clinical discovery platform to prioritize pathways for assessment as therapeutic targets and to test the hypothesis that the primary site harbors potentially lethal tumors after aggressive treatment.

PATIENTS AND METHODS

Patients with locally advanced or lymph node-metastatic prostate cancer underwent 1 year of androgen ablation and three cycles of docetaxel therapy, followed by prostatectomy. All specimens were characterized for stage by accepted criteria. Expression of select molecular markers implicated in disease progression and therapy resistance was determined immunohistochemically and compared with that in 30 archived specimens from untreated patients with high-grade prostate cancer. Marker expression was divided into three groups: intracellular signaling pathways, stromal-epithelial interaction pathways, and angiogenesis.

RESULTS

Forty patients were enrolled, 30 (75%) of whom underwent prostatectomy and two (5%) who underwent cystoprostatectomy. Twenty-nine specimens contained sufficient residual tumor for inclusion in a tissue microarray. Immunohistochemical analysis showed increased epithelial and stromal expression of CYP17, SRD5A1, and Hedgehog pathway components, and modulations of the insulin-like growth factor I pathway.

CONCLUSION

A network of molecular pathways reportedly linked to prostate cancer progression is activated after 1 year of therapy; biomarker expression suggests that potentially lethal cancers persist in the primary tumor and may contribute to progression.

Androgen stimulates endothelial cell proliferation via an androgen receptor/VEGF/cyclin A-mediated mechanism

Growing evidences support that androgen displays beneficial effects on cardiovascular functions although the mechanism of androgen actions remains to be elucidated. Modulation of endothelial cell growth and function is a potential mechanism of androgen actions. We demonstrated in the present study that androgens [dihydrotestosterone (DHT) and testosterone], but not 17β-estradiol, produced a time- and dose-dependent induction of cell proliferation in primary human aortic endothelial cells (HAECs) as evident by increases in viable cell number and DNA biosynthesis. Real-time qRT-PCR analysis showed that DHT induced androgen receptor (AR), cyclin A, cyclin D1, and vascular endothelial growth factor (VEGF) gene expression in a dose- and time-dependent manner. The addition of casodex, a specific AR antagonist, or transfection of a specific AR siRNA blocked DHT-induced cell proliferation and target gene expression, indicating that the DHT effects are mediated via AR. Moreover, coadministration of SU5416 to block VEGF receptors, or transfection of a specific VEGF-A siRNA to knockdown VEGF expression, produced a dose-dependent blockade of DHT induction of cell proliferation and cyclin A gene expression. Interestingly, roscovitine, a selective cyclin-dependent kinase inhibitor, also blocked the DHT stimulation of cell proliferation with a selective inhibition of DHT-induced VEGF-A expression. These results indicate that androgens acting on AR stimulate cell proliferation through upregulation of VEGF-A, cyclin A, and cyclin D1 in HAECs, which may be beneficial to cardiovascular functions since endothelial cell proliferation could assist the repair of endothelial injury/damage in cardiovascular system.

Therapeutic targeting of the prostate cancer microenvironment

Solid tumors can be thought of as multicellular 'organs' that consist of a variety of cells as well as a scaffold of noncellular matrix. Stromal-epithelial crosstalk is integral to prostate cancer progression and metastasis, and androgen signaling is an important component of this crosstalk at both the primary and metastatic sites. Intratumoral production of androgen is an important mechanism of castration resistance and has been the focus of novel therapeutic approaches with promising results. Various other pathways are important for stromal-epithelial crosstalk and represent attractive candidate therapeutic targets. Hedgehog signaling has been associated with tumor progression, growth and survival, while Src family kinases have been implicated in tumor progression and in regulation of cancer cell migration. Fibroblast growth factors and transforming growth factor beta signaling regulate cell proliferation, apoptosis and angiogenesis in the prostate cancer microenvironment. Integrins mediate communication between the cell and the extracellular matrix, enhancing growth, migration, invasion and metastasis of cancer cells. The contribution of stromal-epithelial crosstalk to prostate cancer initiation and progression provides the impetus for combinatorial microenvironment-targeting strategies.

Thrombospondin-1 regulates the normal prostate in vivo through angiogenesis and TGF-beta activation

Castration experiments in rodents show that the stromal vasculature is critical to the androgen-mediated prostate growth regulation. However, the role of angiogenesis inhibitors, such as thrombospondin-1 (TSP-1), in this process is unclear. TSP-1 is a multifunctional glycoprotein that can function as a potent angiogenesis inhibitor and an in vivo activator of latent transforming growth factor-beta (TGF-beta) in some tissues. On the basis of these observations, we hypothesized that TSP-1 regulated androgen withdrawal-induced prostate regression and that this process was mediated not only through antiangiogenic activity but also through TGF-beta activation. To test this, we evaluated angiogenic activity in human prostate epithelial and stromal cells treated with androgens and hypoxia in vitro. TSP-1 knockout mice were characterized to investigate the in vivo functions of TSP-1. In vitro, we found that androgens and hypoxia differentially regulated TSP-1 and angiogenic activity. Androgens stimulated normal epithelial cell, but inhibited normal stromal cell, angiogenic activity. Conversely, hypoxia stimulated stromal while inhibiting epithelial activity. Thus, in vivo, net angiogenic activity must reflect cellular interactions. And, we found that media conditioned by epithelial cells grown under normoxic conditions stimulated stromal cell angiogenic activity, and if epithelial cells were grown under hypoxic conditions, stromal activity was further increased. TSP-1 levels, however, were unchanged. In vivo, TSP-1 loss in a mouse model led to prostate epithelial hyperplasia by 3 months of age with only a modest stromal effect. Androgens suppressed TSP-1 as expression increased after castration both in normal mouse prostate and in human prostate cancer tissues. In addition, TSP-1 expression corresponded to increased TGF-beta activation in mouse tissues, specifically in the stromal compartment. These data show a critical role for TSP-1 in prostate epithelial and stromal growth regulation through angiogenic inhibition and activation of latent TGF-beta. Therefore, loss of TSP-1 during tumorigenesis would eliminate two barriers to cancer progression.

Effect of dutasteride on the expression of hypoxia-inducible factor-1alpha, vascular endothelial growth factor and microvessel density in rat and human prostate tissue

OBJECTIVE

To evaluate the effects of dutasteride on the expression of angiogenesis markers in rat and human prostates.

MATERIAL AND METHODS

Eight-week-old male Sprague-Dawley rats were divided into three groups of six each according to dutasteride dose, including the control group (regular diet), 2.5 mg group (2.5 mg/kg dutasteride) and 5.0 mg group (5.0 mg/kg dutasteride). A total of 41 patients awaiting transurethral resection of the prostate (TURP) were divided into two groups: 20 patients received no medication and 21 received 0.5 mg dutasteride daily for 2-4 weeks until TURP.

RESULTS

At 2 weeks, dutasteride effected a significant decrease in body weight and prostate weight compared with the control rat group. Analysis by reverse transcription-polymerase chain reaction and Western blot revealed that hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) expression was lower in the dutasteride-treated groups than in the control group, except for HIF-1alpha protein. HIF-1alpha and VEGF expression was similar in the 2.5 mg and 5.0 mg groups. Human prostate tissues demonstrated homogeneous staining of HIF-1alpha and VEGF with regard to extent, intensity and intracellular location in both groups. There was no significant difference in microvessel density between the two groups.

CONCLUSIONS

The expression of HIF-1alpha and VEGF in rat prostates is suppressed by dutasteride. However, less than 4 weeks of dutasteride administration does not suppress the expression of HIF-1alpha, VEGF and microvessel density in human prostate tissue. Further clinical investigation with dutasteride including a larger, placebo-controlled study is warranted to establish the mechanism and duration of dutasteride.

Stroma-epithelium crosstalk in prostate cancer

The critical role played by stroma-epithelium crosstalk in carcinogenesis and progression of prostate cancer has been increasingly recognized. These interactions are mediated by a variety of paracrine factors secreted by cancer cells and/or stromal cells. In human prostate cancer, reactive stroma is characterized by an increase in myofibroblasts and a corresponding amplification of extracellular matrix production and angiogenesis. Permanent genetic mutations have been reported in stromal cells as well as in tumour cells. Transforming growth factor-beta, vascular endothelial growth factor, platelet-derived growth factor and fibroblast growth factor signalling pathways are involved in the process of angiogenesis, whereas hepatocyte growth factor, insulin-like growth factor-1, epidermal growth factor, CXC12 and Interleukin-6 play active roles in the progression, androgen-independent conversion and distal metastasis of prostate cancer. Some soluble factors have reciprocal interactions with androgens and the androgen receptor (AR), and can even activate AR in the absence of the androgen ligand. In this article, we review the complex interactions between cancer cells and the surrounding microenvironment, and discuss the potential therapeutic targets in the stromal compartment of prostate cancer.

Androgen receptor and growth factor signaling cross-talk in prostate cancer cells

Androgens promote the growth and differentiation of prostate cells through ligand activation of the androgen receptor (AR). Sensitization of the androgenic response by multifunctional growth factor signaling pathways is one of the mechanisms via which AR contributes to the emergence of androgen-independent prostate tumors. The ability of AR to cross-talk with key growth factor signaling events toward the regulation of cell cycle, apoptosis, and differentiation outcomes in prostate cancer cells is established. In this paper, we review the functional interaction between AR and an array of growth factor signal transduction events (including epidermal growth factor; fibroblast growth factor; IGF1; vascular endothelial growth factor; transforming growth factor-beta) in prostate tumors. The significance of this derailed cross-talk between androgens and key signaling networks in prostate cancer progression and its value as a therapeutic forum targeting androgen-independent metastatic prostate cancer is discussed.

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.

Androgen-dependent gene expression of prostate-specific antigen is enhanced synergistically by hypoxia in human prostate cancer cells

The androgen receptor (AR) is implicated in prostate cancer growth, progression, and angiogenesis. Hypoxia-inducible factor-1 (HIF-1), which transcriptionally regulates hypoxia-inducible angiogenic factors, is up-regulated in prostate cancers compared with adjacent normal tissues. HIF-1 may be involved in prostate cancer as well as the AR, but the involvement of HIF-1 in prostate cancer angiogenesis and progression has not been fully elucidated. In the present study, we found that in prostate cancer LNCaP cells dihydrotestosterone enhanced the expression of GLUT-1, one of the HIF-1 target genes, and also that hypoxia enhanced the expression of prostate-specific antigen (PSA) that is one of the AR target genes and is involved in tumor invasion. Small interfering RNA that specifically inhibits HIF-1 reduced the expression levels of PSA as well as GLUT-1. Reporter gene analysis showed that dihydrotestosterone activated the HIF-1-mediated gene expression and hypoxia enhanced the AR-induced promoter activity of human PSA gene. Deletion and site-directed mutation of the 5'-flanking region of human PSA gene revealed that the sequence ACGTG between -3951 and -3947 was essential in the response to hypoxia. Furthermore, chromatin immunoprecipitation assay indicated that HIF-1 interacts with the AR on the human PSA gene promoter. These results indicated that in prostate cancers, HIF-1 might cooperate with the AR to activate the expression of several genes related to tumor angiogenesis, invasion, and progression.

Effect of hypoxia on the release of vascular endothelial growth factor and testosterone in mouse TM3 Leydig cells

Hypoxia has been shown to stimulate the expression of vascular endothelial growth factor (VEGF), which is a major mediator for angiogenesis and vasculogenesis. During hypoxia, VEGF promotes angiogenesis in the testis. However, the effect of VEGF on the steroidogenesis of testosterone and the cell proliferation in Leydig cells is unclear. To assess the effects and the action mechanisms of hypoxia, a mouse TM3 Leydig cell line was employed in the present study. The Leydig cells were incubated in an incubator chamber (95% N2-5% CO2) for 1-24 h. The cultured media were collected and assayed by testosterone RIA and VEGF enzyme immunoassay. 3-(4,50-Dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide assay was used to detect the proliferation of Leydig cells. The present results showed that the proliferation of Leydig cells was enhanced significantly by hypoxia. The basal VEGF release was increased, and the response of VEGF production to human chorionic gonadotropin (hCG) was also enhanced in hypoxic condition. During hypoxia, administration of hCG or VEGF stimulated proliferation of Leydig cells, but the stimulatory effect was abolished by the administration of anti-VEGF antibody. Higher doses of VEGF stimulated testosterone release in a dose-dependent manner. Administration of anti-VEGF antibody abolished the stimulatory effect of VEGF on testosterone release. These data suggest that hypoxia stimulates cell proliferation and testosterone release in Leydig cells via an increase of VEGF production.

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.

Advances in the Treatment of Prostate Cancer

Several recent advances have been made in the management of prostate cancer. Active surveillance is an increasingly attractive and reasonable approach for those with low-volume, low-risk disease. For locally advanced or localized high-risk disease, neoadjuvant and adjuvant therapies are emerging as the standard of care. Innovative uses of traditional hormonal treatments can potentially limit common side effects. Recent data also support the utility of second-line hormonal therapy. For the first time, a survival advantage with the use of chemotherapy has been established. Much work is under way to augment its efficacy with novel agents such as targeted therapeutics and tumor vaccines. Recent scientific breakthroughs suggest additional strategies in treating prostate cancer.

Activation of vascular endothelial growth factor (VEGF) by the ER-alpha variant, ERDelta3

Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis in estrogen responsive tissues. Estrogen receptors alpha and beta regulate production of VEGF in both breast and endometrial cancer cells. Alternative splicing of ER-alpha mRNA generates a mixture of transcripts with various exon deletions in normal breast and breast cancer cells and some of these variants are overexpressed in breast cancer. We analyzed the role of exon-deleted variants of ER-alpha in regulation of VEGF production by simultaneous transient transfection of CHO and MDA-MB-231 cells with a VEGF promoter luciferase construct. Estrogen (10 nM) treatment resulted in a 6-fold increase in luciferase activity in cells transfected with the exon 3 deleted variant (ERDelta3) compared to a 2-fold activity induction in cells transfected with wild type ER-alpha. Exon 5 and exon 7 deleted variants were unable to induce activation of the VEGF promoter. Using specific deletion constructs of the VEGF promoter linked to luciferase, we showed that the majority of activation by ERDelta3 was restricted to the -70 to -88 bp fragment that contains two Sp1 sites. Site-directed mutagenesis of both Sp1 sites indicated that ERDelta3 activates the VEGF promoter through interaction with Sp1 proteins. ERDelta3, a variant frequently overexpressed in breast cancer, may significantly contribute to the production of VEGF thus resulting in enhanced tumor growth in vivo.

A prostate secretory protein94-derived synthetic peptide PCK3145 inhibits VEGF signalling in endothelial cells: implication in tumor angiogenesis

We have previously observed that the synthetic peptide corresponding to amino acids 31-45 (PCK3145) of PSP94 can reduce prostate tumor growth in vivo. Moreover, a recently concluded phase IIa clinical trial with patients with hormone refractory prostate cancer indicated that PCK3145 down-regulates the levels of plasma matrix metalloproteinase (MMP)-9, a MMP involved in metastasis and tumor angiogenesis. The purpose of our study was to investigate the molecular mechanisms of action of PCK3145 and whether this peptide could antagonize tumor neovascularization. We show that, in a syngeneic in vivo model of rat prostate cancer, the expression of endothelial cell (EC) specific CD31, a marker of tumor vessel density, was decreased by 43% in PCK3145-treated animals. In vitro, PCK3145 specifically antagonized in a dose-dependent manner the VEGF-induced ERK phosphorylation as well as the phosphorylation of the VEGFR-2 in cultured EC (HUVEC). These anti-VEGF effects were partly reproduced by pharmacological inhibitors such as PD98059 and PTK787, suggesting that PCK3145 inhibits the tyrosine kinase activity associated to VEGFR-2, which in turn prevents intracellular signalling through the MAPK cascade. Moreover, PCK3145 was also found to inhibit the PDGF-induced phosphorylation of PDGFR in smooth muscle cells. Finally, PCK3145 inhibited in vitro EC tubulogenesis and VEGF-induced MMP-2 secretion suggesting its potential implication as an antiangiogenic agent. Our study demonstrates that PCK3145 interferes with the tyrosine kinase activity associated with VEGF signalling axis in EC. The antiangiogenic properties of this peptide could be highly beneficial and exploited in novel antiangiogenic therapies, for patients with various cancers.

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.

Sex steroids have differential effects on growth and gene expression in primary human prostatic epithelial cell cultures derived from the peripheral versus transition zones

The majority of human prostate cancers arise from the peripheral zone (PZ). Prostate epithelial stem cells have been localized to the basal epithelial cell compartment. In addition, basal cells have been shown to maintain luminal epithelial cell differentiation and may mediate signals between the stromal and luminal cell compartments. Therefore, the study of adult prostate basal cells derived from different prostate zones may give insights into the mechanisms underlying normal and abnormal prostate growth. We herein compare the basal and sex steroid-stimulated expression and activity of several genes/proteins that are known to be critical in prostate cancer development in primary cultures of basal cells derived from the transition zone (TZ) and PZ of prostatectomy specimens. Our results demonstrate that prostate basal cells derived from the PZ versus TZ are more viable in culture, particularly in response to sex steroid addition. PZ cells exhibit higher telomerase activity and increased expression levels of androgen receptor, the anti-apoptotic protein bcl-2, and the dominant-negative splice variant of Kruppel-like Factor 6. PZ cells have lower basal expression levels of estrogen receptor-beta, the pro-apoptotic protein Bax, and cell-cycle inhibitor proteins (p53, p21(waf1/Cip1)). Finally, we demonstrate divergent responses to sex hormones in the two basal cell populations. The gene expression pattern in the PZ cells may partially explain the predominance of prostate cancer development in this region.

Short-term human prostate primary xenografts: an in vivo model of human prostate cancer vasculature and angiogenesis

Transgenic spontaneously occurring and transplantable xenograft models of adenocarcinoma of the prostate (CaP) are established tools for the study of CaP progression and metastasis. However, no animal model of CaP has been characterized that recapitulates the response of the human prostate vascular compartment to the evolving tumor microenvironment during CaP progression. We report that primary xenografts of human CaP and of noninvolved areas of the human prostate peripheral zone transplanted to athymic nude mice provide a unique model of human angiogenesis occurring in an intact human prostate tissue microenvironment. Angiogenesis in human kidney primary xenografts established from human renal cell carcinoma and noninvolved kidney tissue, a highly vascular organ and cancer, was compared with angiogenesis in xenografts from the relatively less vascularized prostate. Immunohistochemical identification of the human versus mouse host origin of the endothelial cells and of human endothelial cell proliferation in the human prostate and human kidney xenografts demonstrated that: (a) the majority of the vessels in primary xenografts of benign and malignant tissue of both organs were lined with human endothelial cells through the 30-day study period; (b) the mean vessel density was increased in both the CaP and benign prostate xenografts relative to the initial tissue, whereas there was no significant difference in mean vessel density in the renal cell carcinoma and benign kidney xenografts compared with the initial tissue; and (c) the number of vessels with proliferating endothelial cells in primary xenografts of CaP and benign prostate increased compared with their respective initial tissue specimens, whereas the number of vessels with proliferating endothelial cells decreased in the benign kidney xenografts. Short-term primary human prostate xenografts, therefore, represent a valuable in vivo model for the study of human angiogenesis within a human tissue microenvironment and for comparison of angiogenesis in CaP versus benign prostate.

Regulation of vascular endothelial growth factor production by Leydig cells in vitro: the role of protein kinase A and mitogen-activated protein kinase cascade

We previously reported the presence of vascular endothelial growth factor (VEGF) in testicular cells, and high concentrations of VEGF have been measured in semen, although its role in male reproduction remains obscure. In the present study we focus on understanding the mechanism of VEGF production by mouse Leydig cells cultured in vitro. Production of VEGF protein in medium by testicular cells was markedly increased by the addition of hCG in a time- and dose-dependent manner. Gonadotropin-stimulated VEGF production was mediated by cAMP-dependent protein kinase A (PKA), as evidenced by the effect of hCG being mimicked by 8Br-cAMP and being abolished in the presence of a PKA-specific inhibitor, H-89. Protein kinase C was not involved, as evidenced by phorbol 12-myristate 13-acetate having no influence on VEGF production by Leydig cells. In addition to hCG, atrial natriuretic peptide was also able to stimulate VEGF production, suggesting that cGMP is able to cross-activate PKA. A specific Src kinase inhibitor, PP2, could completely block the stimulatory effects of both gonadotropin and 8Br-cAMP on VEGF production by Leydig cells, implying an involvement of the Src kinase pathway. Furthermore, addition of U0126, an inhibitor of MEK 1/2, abolished the increase in VEGF production stimulated by both hCG and 8Br-cAMP. A similar inhibitory effect was observed by the addition of SB203580, a p38 mitogen-activated protein kinase inhibitor. Thus, in conclusion, Leydig cells are able to produce VEGF by a process under gonadotropic control, and PKA plays a key role in this process. Downstream of PKA, it appears that both MEK 1/2 and Src kinase-dependent pathways are involved, although further research will be necessary to determine the precise link between PKA and other kinases involved.