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

PIK3CA and CCM mutations fuel cavernomas through a cancer-like mechanism

Vascular malformations are thought to be monogenic disorders that result in dysregulated growth of blood vessels. In the brain, cerebral cavernous malformations (CCMs) arise owing to inactivation of the endothelial CCM protein complex, which is required to dampen the activity of the kinase MEKK31-4. Environmental factors can explain differences in the natural history of CCMs between individuals5, but why single CCMs often exhibit sudden, rapid growth, culminating in strokes or seizures, is unknown. Here we show that growth of CCMs requires increased signalling through the phosphatidylinositol-3-kinase (PI3K)-mTOR pathway as well as loss of function of the CCM complex. We identify somatic gain-of-function mutations in PIK3CA and loss-of-function mutations in the CCM complex in the same cells in a majority of human CCMs. Using mouse models, we show that growth of CCMs requires both PI3K gain of function and CCM loss of function in endothelial cells, and that both CCM loss of function and increased expression of the transcription factor KLF4 (a downstream effector of MEKK3) augment mTOR signalling in endothelial cells. Consistent with these findings, the mTORC1 inhibitor rapamycin effectively blocks the formation of CCMs in mouse models. We establish a three-hit mechanism analogous to cancer, in which aggressive vascular malformations arise through the loss of vascular 'suppressor genes' that constrain vessel growth and gain of a vascular 'oncogene' that stimulates excess vessel growth. These findings suggest that aggressive CCMs could be treated using clinically approved mTORC1 inhibitors.

Testosterone promotes GPX5 expression of goat epididymal epithelial cells cultured in vitro

Androgens are involved in maintaining epididymal structure and function. In the present study, primary culture of goat EECs and effect of testosterone on expression of glutathione peroxidase-5 (GPX5) in goat epididymal epithelial cells (EECs) were investigated. The EECs isolated from 12-mo-old goat caput epididymis were cultured with testosterone in vitro, and expression of glutathione peroxidase-5 (GPX5) and androgen receptors (ARs) was analyzed. Our results showed that testosterone effectively increased EEC proliferation activity, and EECs cultured with testosterone could maintain molecular markers for up to 12 passages. Compared with the control group, 100 nM testosterone significantly increased the mRNA and protein expression of GPX5 (P < 0.05) and ARs (P < 0.01 and P < 0.05, respectively) in EECs, and this effect was blocked by the AR blocker enzalutamide. In conclusion, testosterone can promote the expression of GPX5 in EECs by up-regulating AR expression. We established an effective culture system for goat EECs which can be for further investigation on the regulation of epithelial function.

THE EFFECT OF TESTOSTERONE AND VOLUNTARY EXERCISE, ALONE OR TOGETHER, ON miRNA-126 EXPRESSION CHANGES IN HEART OF DIABETIC RATS

Methods

Ninety Wistar male rats were used in this study. Type 1 diabetes was induced by i.p injection of 50 mg/kg of streptozotocin in all animals. After 42 days of treatment with testosterone (2mg/kg/day) or voluntary exercise alone or in combination, the heart of the rats has been removed and MicroRNA was extracted from the heart using miRCURYTM RNA isolation kit.

Results

Our results showed that either testosterone or exercise increased miRNA-126 expression levels in the heart of diabetic rats. Treatment of diabetic rats with testosterone and exercise at the same time had a synergistic effect on miRNA-126 levels in the heart. Furthermore, in castrated diabetes group, miRNA-126 levels were significantly decreased in heart, whereas either testosterone treatment or exercise training enhanced expression of this miRNA. Also, simultaneous treatment of castrated diabetic rats with testosterone and exercise had an additive effect on miRNA-126 expression levels.

Conclusion

This study showed that testosterone and exercise promote an increase in the expression of miRNA-126 in the heart tissue and this may be related to cardiac angiogenesis. These results may indicate that testosterone and exercise can help to prevent progression of diabetic cardiomyopathy due to impaired angiogenesis in the heart.

Testosterone and Voluntary Exercise, Alone or Together Increase Cardiac Activation of AKT and ERK1/2 in Diabetic Rats

Background

Impaired angiogenesis in cardiac tissue is a major complication of diabetes. Protein kinase B (AKT) and extracellular signal regulated kinase (ERK) signaling pathways play important role during capillary-like network formation in angiogenesis process.

Objectives

To determine the effects of testosterone and voluntary exercise on levels of vascularity, phosphorylated Akt (P- AKT) and phosphorylated ERK (P-ERK) in heart tissue of diabetic and castrated diabetic rats.

Methods

Type I diabetes was induced by i.p injection of 50 mg/kg of streptozotocin in animals. After 42 days of treatment with testosterone (2mg/kg/day) or voluntary exercise alone or in combination, heart tissue samples were collected and used for histological evaluation and determination of P-AKT and P-ERK levels by ELISA method.

Results

Our results showed that either testosterone or exercise increased capillarity, P-AKT, and P-ERK levels in the heart of diabetic rats. Treatment of diabetic rats with testosterone and exercise had a synergistic effect on capillarity, P-AKT, and P-ERK levels in heart. Furthermore, in the castrated diabetes group, capillarity, P-AKT, and P-ERK levels significantly decreased in the heart, whereas either testosterone treatment or exercise training reversed these effects. Also, simultaneous treatment of castrated diabetic rats with testosterone and exercise had an additive effect on P-AKT and P-ERK levels.

Conclusion

Our findings suggest that testosterone and exercise alone or together can increase angiogenesis in the heart of diabetic and castrated diabetic rats. The proangiogenesis effects of testosterone and exercise are associated with the enhanced activation of AKT and ERK1/2 in heart tissue.

Anti-Müllerian Hormone Is a Marker for Chemotherapy-Induced Testicular Toxicity

Due to increased numbers of young cancer patients and improved survival, the impact of anticancer treatments on fertility has become a major health concern. Despite mounting research on ovarian toxicity, there is paucity of data regarding reliable biomarkers of testicular toxicity. Our aim was to evaluate anti-Müllerian hormone (AMH) as a marker for chemotherapy-induced testicular toxicity. Serum AMH and a panel of gonadal hormones were measured in male cancer patients at baseline and after chemotherapy. In the preclinical setting, mice were injected with diverse chemotherapies and were killed 1 week or 1, 3, or 6 months later. We evaluated spermatogenesis by AMH as well as qualitative and quantitative sperm parameters. Nineteen patients were enrolled, the median age was 38 years (21-44 y). Serum AMH was correlated with increased FSH and T and decreased inhibin-B in gonadotoxic protocols (cisplatin or busulfan) and remained unchanged in nongonadotoxic protocols (capecitabine). AMH expression had the same pattern in mice serum and testes; it was negatively correlated with testicular/epididymal weight and sperm motility. The increase in testicular AMH expression was also correlated with elevated apoptosis (terminal transferase-mediated deoxyuridine 5-triphosphate nick-end labeling) and reduced proliferation (Ki67, proliferating cell nuclear antigen; all seminiferous tubules cells were analyzed). Severely damaged mice testes demonstrated a marked costaining of AMH and GATA-4, a Sertoli cell marker; staining that resembled the pattern of the Sertoli cell-only condition. Our study indicates that the pattern of serum AMH expression, in combination with other hormones, can delineate testicular damage, as determined in both experimental settings. Future large-scale clinical studies are warranted to further define the role of AMH as a biomarker for testicular toxicity.

Dexrazoxane exacerbates doxorubicin-induced testicular toxicity

Infertility induced by anti-cancer treatments pose a major concern for cancer survivors. Doxorubicin (DXR) has been previously shown to exert toxic effects on the testicular germinal epithelium. Based upon the cardioprotective traits of dexrazoxane (DEX), we studied its potential effect in reducing DXR-induced testicular toxicity. Male mice were injected with 5 mg/kg DXR, 100 mg/kg DEX, combination of both or saline (control) and sacrificed either 1, 3 or 6 months later. Testes were excised and further processed. Glutathione and apoptosis assays were performed to determine oxidative stress. Immunohistochemistry and confocal microscopy were used to study the effects of the drugs on testicular histology and on spermatogonial reserve. DXR and the combined treatment induced a striking decline in testicular weight. DEX prevented DXR-induced oxidative stress, but enhanced DXR-induced apoptosis within the testes. Furthermore, the combined treatment depleted the spermatogonial reserve after 1 month, with impaired recovery at 3 and 6 months post-treatment. This resulted in compromised sperm parameters, testicular and epididymal weights as well as significantly reduced sperm motility, all of which were more severe than those observed in DXR-treated mice. The activity of DEX in the testis may differ from its activity in cardiomyocytes. Adding DEX to DXR exacerbates DXR-induced testicular toxicity.

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.

Immunohistochemical studies on the bovine lactating mammary gland (Bos taurus)

The study aimed to evaluate the validity of immunohistochemistry in the differential labeling of the diverse components of the lactating mammary gland. Paraffin-embedded sections of lactating bovine mammary glands were stained by conventional and histochemical techniques. Primary antibodies against S100, alpha smooth muscle actin (α-SMA), connexin-43 (Cx43), cytokeratin-14 (Ck14), galactosyltransferase (GalTase), angiotensin converting enzyme (ACE) and vascular endothelial growth factor (VEGF) were applied on paraffin sections. Strong cytoplasmic and nuclear S100 immunoreactivity was mainly expressed by alveolar epithelium and to a lesser variable extent by ductal epithelium. The Golgi zone of the epithelial cells expressed strong GalTase immunostaining. Myoepithelial cells displayed a strong immunostaining for α-SMA, Cx43 and Ck14, but not for S100. Vascular endothelium showed a moderate (for VEGF) to strong (for ACE) immunostaining. The presence of VEGF-immunoreactive mast cells within the interstitium may reflect their functional significance in angiogenesis, vascular permeability and migration of mononuclear leukocytes, suggesting their regulatory role in the secretory and immunological functions of the mammary glands.

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.

Immunohistochemical study of angiogenesis and angiogenic factors in equine granulosa cell tumours

The first part of our study (Müller et al., 2009) characterized angiogenesis in the equine cycling ovary through histomorphological and immunohistochemical examinations (vascular endothelial growth factors A and B [VEGF A, VEGF B], vascular endothelial growth factor receptors 1 and 2 [VEGF-R1, VEGF-R2], vascular angiopoietins 1 and 2 [Ang1, Ang2], angiopoietin receptor [Tie2], and von Willebrand Factor). Since angiogenesis plays an important role in development and growth of numerous tumours, the second part of our study involved a similar examination of 70 equine granulosa cell tumours (GCTt). The results of the second study were compared with those of the normal equine ovary. Certain similarities in the expression pattern could be detected between normal, cyclical ovaries (Müller et al., 2009) and GCTt. The immunoreactivity of granulosa cells and Leydig-like cells in GCTt resembles granulosa cells and luteinized thecal cells in periovulatory cycling ovaries. The neoplastic cells support circulation, supply and growth of GCTt by contributing to angiogenesis.

Immunohistochemical studies of the epididymal duct in Egyptian water buffalo (Bubalus bubalis)

Using immunohistochemistry (IHC), this study aimed to evaluate the regional distribution pattern of some biologically active proteins in the epididymis of Egyptian water buffalo and to determine the structural-functional relationships of the different epididymal structures. Wax-embedded sections from different regions of the epididymal duct from adult, clinically healthy, buffalo bulls were used. Primary antibodies against angiotensin converting enzyme (ACE), S-100, galactosyltransferase (GalTase), alpha smooth muscle actin (α-SMA), connexin 43 (Cx43) and vascular endothelial growth factor (VEGF) were used for immunohistochemical studies. The results showed that, in addition to the well-known principal and basal cells, the epididymal epithelium, similar to that of other species, possessed apical cells and intraepithelial leukocytes. IHC showed that, with the exception of VEGF which reacted negatively, all antibodies used displayed variable reactivity in the different epididymal structures. Apical cells expressed a strong reaction with ACE along the entire length of the duct. The principal cells in the caput epididymis exhibited a distinct reactivity with S-100 and GalTase. The peritubular muscular coat displayed a marked immunostaining for α-SMA and for Cx43. In conclusion these findings showed a regional-specific distribution pattern, distinct from that in bovine bulls. Some potential functional capacities, especially absorptive and secretory ones, are discussed in relation to the different epididymal regions.

Xenografting as a tool to preserve endangered species: outcomes and challenges in model systems

The use of testis tissue xenografting as a valuable tool to rescue endangered and genetically valuable individuals that die young or otherwise fail to produce sperm has been the subject of much interest. Although the technique has been successfully applied to a wide variety of species, little is known about what determines the outcome. Furthermore, to improve the applicability of xenografting, new methods to preserve and transport testis tissue from valuable animals are emerging. However, one major issue remains: the application of xenografting implies the development of subsequent ART techniques to produce offspring from the recovered material. This paper focuses on these three aspects of testis tissue xenografting as a tool for rescuing endangered and valuable genetic pools.

Testicular angiogenic activity in response to food restriction in rabbits

The objective of this study was to evaluate the effects of two different levels of food restriction on testicular angiogenic activity, microvascularization, tissue growth, and regression, using the rabbit as a study model. The rabbits (Oryctolagus cuniculus cuniculus) were randomly assigned to a control group (A, n=5), fed ad libitum, and to groups B (n=5) and C (n=5), with two different levels of food restriction. Food restriction was responsible for a 21.2% decrease in body weight in group B and 34.7% in group C. Testis explants were cultured for 24 h and conditioned media were tested for their ability to stimulate mitogenesis of bovine aortic endothelial cells (BAEC). There was an increase in testicular microvascular area and mitogenesis of BAEC in group C rabbits. Despite no change in testicular DNA concentration among groups, food restriction decreased both RNA and protein compared with control. No treatment differences in the percentage of seminiferous tubules filled with all stages of spermatogenesis (spermatogonia, spermatocytes, and spermatids) and spermatozoa, as well as the area occupied by seminiferous tubules, were observed. Nevertheless, serum testosterone was markedly less in group C compared with groups A and B. These results suggest that angiogenesis may play a role in overcoming testicular nutritional impairment in rabbits subjected to food restriction.

Androgen receptor targets NFkappaB and TSP1 to suppress prostate tumor growth in vivo

The androgen role in the maintenance of prostate epithelium is subject to conflicting opinions. While androgen ablation drives the regression of normal and cancerous prostate, testosterone may cause both proliferation and apoptosis. Several investigators note decreased proliferation and stronger response to chemotherapy of the prostate cancer cells stably expressing androgen receptor (AR), however no mechanistic explanation was offered. In this paper we demonstrate in vivo anti-tumor effect of the AR on prostate cancer growth and identify its molecular mediators. We analyzed the effect of AR on the tumorigenicity of prostate cancer cells. Unexpectedly, the AR-expressing cells formed tumors in male mice at a much lower rate than the AR-negative controls. Moreover, the AR-expressing tumors showed decreased vascularity and massive apoptosis. AR expression lowered the angiogenic potential of cancer cells, by increasing secretion of an anti-angiogenic protein, thrombospondin-1. AR activation caused a decrease in RelA, a subunit of the pro-survival transcription factor NFkappaB, reduced its nuclear localization and transcriptional activity. This, in turn, diminished the expression of its anti-apoptotic targets, Bcl-2 and IL-6. Increased apoptosis within AR-expressing tumors was likely due to the NFkappaB suppression, since it was restricted to the cells lacking nuclear (active) NFkappaB. Thus we for the first time identified combined decrease of NFkappaB and increased TSP1 as molecular events underlying the AR anti-tumor activity in vivo. Our data indicate that intermittent androgen ablation is preferable to continuous withdrawal, a standard treatment for early-stage prostate cancer. (c) 2007 Wiley-Liss, Inc.

Castration rapidly decreases local insulin-like growth factor-1 levels and inhibits its effects in the ventral prostate in mice

BACKGROUND

The mechanisms by which castration induces prostate involution are largely unknown.

METHODS

Early responses to castration in mouse ventral prostate (VP) were explored by quantitative microscopy, cDNA array expression, quantitative RT-PCR, and Western blot analysis. As several changes occurred in the insulin-like growth factor (IGF) system this was studied in more detail. Laser micro-dissection was used to localize sites of IGF-1 and IGF-1 receptor (IGF-R1) production. IGF-1 protein levels and IGF-R1 mediated signaling via insulin regulated substrate 1 and 2 (IRS-1 and 2) were examined. IGF-1 was injected into the VP in intact, and castrated mice and effects studied 1 day later.

RESULTS

IGF-1 and IGF binding protein 2 (IGFBP-2) mRNA were rapidly reduced whereas IGFBP-3 and IGF-R1 mRNA were increased after castration. IGF-1 was principally produced in the stromal compartment, while IGF-R1 was produced in both epithelial and stromal cells. IGF-1 and IRS-1 protein levels were decreased 1 and 3 days after castration, respectively, while IRS-2 was unchanged. Inactivating phosphorylation of IRS-1 at serine 307 was increased 1 day after castration, and activating phosphorylation at tyrosine 612 was decreased 2 days later. These changes were accompanied by decreased cell proliferation and increased cell death in the glandular and vascular compartment. Local injection of IGF-1 increased vascular density and epithelial cell proliferation in intact mice, but had no effect in castrated animals.

CONCLUSION

Decreased IGF-1 levels and action may mediate some of the key features of castration-induced prostate involution.

Male castration increases neuronal nitric oxide synthase activity in the rat mesenteric artery through protein kinase C activation

The objective of the present study was to assess the effect of endogenous male sex hormones on the activity of protein kinase C (PKC), as well as the regulatory effect of this kinase on the neuronal nitric oxide (NO) release induced by electrical field stimulation (EFS; 200 mA; 0.3 ms; 1-16 Hz). For this purpose, superior mesenteric arteries from control and orchidectomized male Sprague-Dawley rats were used. PKC activity was greater in arteries from orchidectomized than control rats. Basal and EFS-induced NO release was similar in arteries from both groups despite the lower nNOS expression in arteries from orchidectomized rats. Phorbol 12,13-dibutyrate (PDBu), a PKC activator, EFS-induced NO release was higher in arteries from control compared to orchidectomized rats. Calphostin C, a non-selective PKC inhibitor, or Gö6976, a PKC inhibitor partially selective for conventional isoforms,abolished the EFS-induced NO release in arteries from control animals, while it was decreased in arteries from orchidectomized animals. The PKCzeta pseudosubstrate inhibitor decreased EFS-induced NO release equally in both groups. The NO synthase (NOS) inhibitor Nomega-nitro-L-arginine-methyl ester (L-NAME) enhanced the EFS-elicited contractions in arteries from both groups. Calphostin C increased the contractions elicited by EFS in arteries from control and orchidectomized rats. This increase was further enhanced by calphostin C plus L-NAME only in orchidectomized rats. PDBu reduced EFS-induced contraction in arteries from controls but did not affect it in orchidectomized rats. The further addition of L-NAME increased the responses in both types of arteries. These results show that PKC activity is enhanced in mesenteric arteries from orchidectomized rats, which may be the responsible for the greater nNOS activity in these arteries. Conventional and atypical PKCzeta isoforms positively regulate nNOS activity in arteries from both control and orchidectomized rats, but the contribution of conventional PKC isoforms to enhanced nNOS activity seems to be greater in arteries from orchidectomized rats.

Quantitative proteomic analysis of sokotrasterol sulfate-stimulated primary human endothelial cells

The endothelium forms a continuous monolayer at the interface between blood and tissue and contributes significantly to the sensing and transducing of signals between blood and tissue. New blood vessel formation, or angiogenesis, is initiated by the activation of endothelial cells and is an important process required for various pathological and physiological situations. This study used cleavable isotope-coded affinity tag reagents combined with mass spectrometry to investigate the molecular basis of a recently discovered angiogenesis-promoting steroid, sokotrasterol sulfate. Changes in the relative abundances of over 1000 proteins within human endothelial cells treated with sokotrasterol sulfate and vehicle-treated cells were identified and quantitated using this technique. A method that examines the entire ensemble of quantitative measurements was developed to identify proteins that showed a statistically significant change in relative abundance resulting from treatment with sokotrasterol sulfate. A total of 93 proteins was significantly up-regulated, and 37 were down-regulated in response to sokotrasterol sulfate stimulation of endothelial cells. Among the up-regulated proteins, several were identified that are novel to endothelial cells and are likely involved in cell communication and morphogenesis. These findings are consistent with a role for sokotrasterol sulfate in endothelial sprouting.

Decreased Pigment Epithelium-Derived Factor Is Associated with Metastatic Phenotype in Human and Rat Prostate Tumors

Pigment epithelium-derived factor, a potent angiogenesis inhibitor in the eye, is also expressed in the prostate. Prostate size and angiogenesis is increased in pigment epithelium-derived factor knockout mice, and pigment epithelium-derived factor is down-regulated in some prostate cancers. To investigate whether pigment epithelium-derived factor expression correlates with tumor progression, we examined 5 Dunning rat prostate sublines with different growth rates, differentiation, androgen dependence, vascular density, and metastatic ability and 26 human prostate cancers of Gleason score 8-10 obtained from patients at transurethral resection selected to represent two groups, with and without metastases at diagnosis. By Western blot, real-time quantitative reverse transcription-PCR, and immunostaining, pigment epithelium-derived factor was detected in highly differentiated, nonmetastatic, androgen-sensitive Dunning tumors and in the anaplastic, androgen insensitive but nonmetastatic Dunning tumors. In contrast, the metastatic Dunning tumor sublines showed very low pigment epithelium-derived factor expression levels. In human cancer tissues, by immunohistochemistry and real-time quantitative reverse transcription-PCR, patients without metastases at diagnosis had higher tumor pigment epithelium-derived factor levels than tumors from patients with metastases at diagnosis. In both the rat model and in the human tumors, the proliferation index and vascular count, as determined by Ki-67 staining and endoglin and/or factor VIII-related antigen staining, inversely correlated with pigment epithelium-derived factor mRNA levels. These observations indicate that loss of pigment epithelium-derived factor expression could be associated with the progression toward a metastatic phenotype in prostate cancer.

Androgen-dependent morphology of prostates and seminal vesicles in the Hershberger Assay: Evaluation of immunohistochemical and morphometric parameters

The aim of this study was to evaluate androgen-like effects using immunohistochemical and morphometric methods. Therefore, orchiectomized Wistar rats (n > or = 13) were treated s.c. with 1 mg/kg bw/day testosterone propionate (TP) for 7 days and compared to orchiectomized rats without TP substitution (OX) and to an untreated intact control group. Sections obtained from prostates and seminal vesicles were stained with polyclonal and monoclonal antibodies against the androgen receptor (AR) and assessed densitometrically (intensity of the immunoreaction) and morphometrically (epithelial height, luminal area). TP caused an enhancement of staining intensity and an increase in organ weights, epithelial height and luminal area. The use of proliferation markers (PCNA, MIB-5) showed also a highly significant increase of immunoreactive cells in TP-substituted orchiectomized rats compared with the OX group. Based on the present data, the densitometric analysis of AR-immunoreactivity as well as the assessment of proliferation markers, epithelial height and luminal area proved to be sensitive parameters for the evaluation of androgen effects on prostates and seminal vesicles. In further studies these parameters will be used to test several industrial xenooestrogens as well as phytooestrogens on their possible androgenic capacity.

Stimulation of TM3 Leydig cell proliferation via GABA(A) receptors: a new role for testicular GABA

The neurotransmitter gamma-aminobutyric acid (GABA) and subtypes of GABA receptors were recently identified in adult testes. Since adult Leydig cells possess both the GABA biosynthetic enzyme glutamate decarboxylase (GAD), as well as GABA(A) and GABA(B) receptors, it is possible that GABA may act as auto-/paracrine molecule to regulate Leydig cell function. The present study was aimed to examine effects of GABA, which may include trophic action. This assumption is based on reports pinpointing GABA as regulator of proliferation and differentiation of developing neurons via GABA(A) receptors. Assuming such a role for the developing testis, we studied whether GABA synthesis and GABA receptors are already present in the postnatal testis, where fetal Leydig cells and, to a much greater extend, cells of the adult Leydig cell lineage proliferate. Immunohistochemistry, RT-PCR, Western blotting and a radioactive enzymatic GAD assay evidenced that fetal Leydig cells of five-six days old rats possess active GAD protein, and that both fetal Leydig cells and cells of the adult Leydig cell lineage possess GABA(A) receptor subunits. TM3 cells, a proliferating mouse Leydig cell line, which we showed to possess GABA(A) receptor subunits by RT-PCR, served to study effects of GABA on proliferation. Using a colorimetric proliferation assay and Western Blotting for proliferating cell nuclear antigen (PCNA) we demonstrated that GABA or the GABA(A) agonist isoguvacine significantly increased TM3 cell number and PCNA content in TM3 cells. These effects were blocked by the GABA(A) antagonist bicuculline, implying a role for GABA(A) receptors. In conclusion, GABA increases proliferation of TM3 Leydig cells via GABA(A) receptor activation and proliferating Leydig cells in the postnatal rodent testis bear a GABAergic system. Thus testicular GABA may play an as yet unrecognized role in the development of Leydig cells during the differentiation of the testicular interstitial compartment.

Localized expression of angiopoietin 1 and 2 may explain unique characteristics of the rat testicular microvasculature

The testicular vasculature is unique in several ways. The unfenestrated endothelial cells constitute one part of the blood-testis barrier, and testicular microvessels are normally resistant to inflammation mediators. At the same time that angiogenic factors and inflammation mediators are constitutively produced, the proportion of proliferating endothelial cells is considerably higher than in other organs, but new blood vessels are not formed. Hormonal stimulation of the testis with hCG increase endothelial cell proliferation, vascular permeability, and sensitivity to locally injected inflammation mediators. In the present study, we examined whether local expression of angiopoietin (ang) 1, an inhibitor of vascular leakage and sprouting angiogenesis, and its antagonist, ang 2, could be involved in establishing this vascular phenotype. Using reverse transcription-polymerase chain reaction and immunohistochemistry, we demonstrate that testicular vascular endothelial growth factor-A (VEGF-A), ang 1, ang 2, and the ang-receptor tie 2 are expressed in the testis and that hormonal stimulation with hCG is accompanied by increased expression of VEGF-A and ang 2. The ang 1 protein is expressed in testicular microvessels under basal conditions, and it is largely unaffected after hCG stimulation. Expression of ang 2 in microvessels, in contrast, is low under basal conditions and is up-regulated by hCG. Intratesticular injection of human recombinant ang 1 protein inhibits hCG-induced increase in vascular permeability. Injection of ang 2 in the testis increases endothelial cell proliferation and the volume of the interstitial space. We therefore suggest that ang 1 stabilizes testicular microvessels under basal conditions and that a shift in this balance caused by increased ang 2, together with increased VEGF-A, allows vascular leakage, high endothelial cell proliferation, and presumably, vascular growth after hormonal stimulation.

Role of connexin37 and connexin40 in vascular development

Mice lacking both connexin37 (Cx37) and connexin40 (Cx40), gap junction proteins expressed in vascular endothelium, die perinatally with pronounced vascular abnormalities. Early vasculogenesis proceeds normally, but by E18.5 Cx37(-/-)Cx40(-/-) animals display vessel dilatation and congestion as well as localized hemorrhages in skin, testis, intestines, and lungs. Abnormal vascular channels are present in the testis, often forming cavernous hemangioma-like defects. Unusually large, distended vessels are also present in the submucosa and lamina propria of the intestine. Ablation of Cx40 has a greater effect on endothelial dye-transfer than ablation of Cx37, and the effect of Cx40 ablation is age-dependent. Only in embryonic aortas lacking both Cx37 and Cx40 is there a complete loss of endothelial coupling. Surprisingly, elimination of Cx40 results in a large drop in aortic endothelial Cx37 on western blots, and deletion of Cx37 also reduces endothelial Cx40 levels. In contrast, in the medial layer, both Cx37 and Cx43 increase when Cx40 is ablated. These studies indicate that Cx37 and Cx40 are collectively critical for endothelial communication and provide evidence of an important role for gap junctions in vascular development. In addition, Cx37 and Cx40 appear to be mutually dependent on each other for normal expression in vascular endothelium.