Synthesis and secretion of angiotensin II by the prostate gland in vitro

Insights into the associative role of hypertension and angiotensin II receptor in lower urinary tract dysfunction

In men, the lower urinary tract comprises the urinary bladder, urethra, and prostate, and its primary functions include urine storage and voiding. Hypertension is a condition that causes multi-organ damage and an age-dependent condition. Hypertension and the renin-angiotensin system activation are associated with the development of lower urinary tract dysfunction. Hypertensive animal models show bladder dysfunction, urethral dysfunction, and prostatic hyperplasia. In the renin-angiotensin system, angiotensin II and the angiotensin II type 1 receptor, which are expressed in the lower urinary tract, have been implicated in the pathogenesis of lower urinary tract dysfunction. Moreover, among the several antihypertensives, renin-angiotensin system inhibitors have proven effective in human and animal models of lower urinary tract dysfunction. This review aimed to elucidate the hitherto known mechanisms underlying the development of lower urinary tract dysfunction in relation to hypertension and the angiotensin II/angiotensin II type 1 receptor axis and the effect of renin-angiotensin system inhibitors on lower urinary tract dysfunction. Possible mechanisms through which hypertension or activation of Ang II/AT1 receptor axis causes LUTD such as bladder dysfunction, urethral dysfunction, and prostatic hyperplasia. LUT: lower urinary tract, LUTD: lower urinary tract dysfunction, AT1: angiotensin II type 1, ACE: angiotensin-converting enzyme.

ACE and ACE2: insights from Drosophila and implications for COVID-19

Angiotensin-converting enzyme (ACE) and its homologue ACE2 are key regulators of the renin-angiotensin system and thereby cardiovascular function through their zinc-metallopeptidase activity on vasoactive peptides. ACE2 also serves as the receptor for the cellular entry of various coronaviruses including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the coronavirus disease 2019 (COVID-19). The unprecedented scale of the COVID-19 pandemic has spurred the use of mammalian models to investigate the SARS-ACE2 relationship and knowledge gained from such research has accelerated development of vaccines and therapeutics. Recent studies have just started to underscore the utility of the fruit fly Drosophila melanogaster as a model system to study virus-host interactions and pathogenicity. Notably, the remarkable existence of catalytically functional ACE and ACE2 orthologues in Drosophila, discovered more than two decades ago, provides a unique opportunity for further developing this model organism to better understand COVID-19 in addition to identifying coronavirus preventative and therapeutic interventions targeting ACE2. Here, we review the studies that revealed crucial insights on the biochemistry and physiology of Ance and Acer, two out of the six Drosophila ACE family members with the greatest homology to human ACE and ACE2. We highlight shared in vivo functions outside of the renin-angiotensin system, which is not conserved in flies. Importantly, we identify knowledge gaps that can be filled by further research and outline ways that can raise Drosophila to a powerful model system to combat SARS-CoV-2 and its threatening vaccine-evading variants.

Therapeutic effects of losartan on prostatic hyperplasia in spontaneously hypertensive rats

AIMS

We investigated the therapeutic effects of losartan, an angiotensin II type 1 receptor blocker, on prostatic hyperplasia in spontaneously hypertensive rats (SHRs).

MAIN METHODS

Male SHRs (age, 36 weeks) were perorally treated with losartan (3 or 10 mg·kg^-1) or vehicle once daily for 18 weeks. Age-matched Wistar Kyoto rats (WKYs) were used as vehicle-treated controls (n = 8). The effects of losartan were evaluated by analyzing prostate weight, blood pressure, and prostatic blood flow. The tissue malondialdehyde (MDA), interleukin-6 (IL-6), and basic fibroblast growth factor (bFGF) levels were measured. Histological analysis for the ventral prostate involved hematoxylin and eosin staining and TdT-mediated dUTP nick-end labeling (TUNEL) assay.

KEY FINDINGS

Compared to the vehicle-treated WKYs, the vehicle-treated SHRs had significantly higher prostate weight, prostate weight/body weight ratio (PBR), blood pressure, glandular epithelial area, and tissue MDA, IL-6, and bFGF levels in the ventral prostate and lower prostatic blood flow. Treatment with losartan caused significant recovery of blood flow and decreased PBR and glandular epithelial area as well as tissue MDA, IL-6, and bFGF levels in the SHR ventral prostate without affecting blood pressure. High-dose losartan significantly decreased blood pressure and increased TUNEL-positive cells in the ventral prostate in SHRs.

SIGNIFICANCE

Chronic losartan treatment could ameliorate prostatic hyperplasia via recovery of reduced prostatic blood flow and induction of apoptosis in the ventral prostate in SHRs. Losartan might have therapeutic effects on not only hypertension but also prostatic hyperplasia in humans.

Effect of Venlafaxine, Pramipexole, and Valsartan on Spermatogenesis in Male Rats

The study's aim was to explore the effect of venlafaxine, valsartan, and pramipexole on spermatogenesis. It was hypothesized that these drugs may affect the male fertility because of their long-term use in treatment of depression, hypertension, and Parkinson's diseases. Male rats were given venlafaxine, valsartan, and pramipexole at low- and high-dose levels orally once daily for 10 weeks. Testosterone (25 mg/kg) was given as a standard via an intramuscular route once weekly. Rats were sacrificed after blood collection by cardiac puncture, and testes were removed. Sperm parameters were examined from spermatozoa of the cauda epididymis, and testes were treated for histopathological analysis. Results showed nonsignificant effect of venlafaxine on the sperm count, whereas a decreased sperm count was noted in all the treatment groups as compared to that of the control except valsartan at a low dose, which significantly (p < 0.001) raised the sperm count (96.26 ± 2.4) in reference with the control value (49.13 ± 2.3). Treatments had variable effects on total sperm motility and morphological parameters, but valsartan at a low dose showed maximum sperm motility (71.55 ± 0.7) among all. DNA integrity of spermatozoa remained intact in all groups. Luteinizing hormone and follicle-stimulating hormone levels decreased, and testosterone levels increased in all treatment groups as compared to control values, which indicate fertility. Histopathology revealed normal texture of testes with venlafaxine and valsartan, but testicular damage occurred with high-dose pramipexole. It is concluded that the use of venlafaxine, valsartan, and pramipexole at a low dose is devoid of any harmful effect on spermatogenesis, whereas pramipexole at a high dose adversely affect it.

Myeloperoxidase and Prostate volume: A preliminary study

OBJECTIVES

Oxidative stress is associated with the development of BPH and might be modulated by several factors. Myeloperoxidase (MPO) has recently been observed in prostate tissue. Our goal was to investigate the correlation between MPO and the prostate volume.

MATERIAL AND METHODS

Hundred and twenty-one patients (48-70 years) with a filled IPSS were prospectively included. Blood sampling (PSA, testosterone, Angiotensin II (AngII), MPO, Mox-LDL) and transrectal ultrasound of the prostate were performed with total volume (TV) and transitional zone volume (TZ) measurements. For correlation, univariate analyses were depicted by Pearson's coefficient. Multilinear regression analysis used a stepwise backward selection of the explicative variables.

RESULTS

In multivariate analysis, the TV was positively correlated to the combination of age and Ang II but negatively to MPO specific activity (Std Coef=-0.272, P=0.004). Significant correlations were confirmed between TZ, age and MPO specific activity but not with Ang II. A negative correlation between TZ and MPO specific activity was also observed (Std Coef=-0.21, P=0.016). No correlation was found with Mox-LDL.

CONCLUSIONS

Negative correlation between MPO and prostate volume was observed but careful interpretations may be endorsed and longitudinal study is necessary. It seems relevant to focus on the potential contribution of MPO in the development of prostatic diseases as this enzyme can also promote DNA oxidation.

LEVEL OF EVIDENCE

4.

Effects of testosterone and 17β‑estradiol on angiotensin‑induced changes in tyrosine kinase activity in the androgen‑independent human prostate cancer cell line, DU145

Angiotensin II (AngII), the main peptide of the renin‑angiotensin system (RAS), is involved in the proliferation of different types of cells, normal and pathological as well. The protein tyrosine kinases (PTKs) play an important role in the growth, differentiation and apoptosis of cells. AngII action depends on the hormonal milieu of the cell, and on sex steroid influence. Angiotensin 1‑7 (Ang1‑7), metabolite of AngII, shows opposite action to AngII in cells. The present study aimed to examine the influence of 17β‑estradiol and testosterone on AngII and Ang1‑7 action on PTK activity in androgen‑independent humane prostate cancer cell line DU145. Cell cultures of human prostate cancer DU145 cells were used as a source of PTKs. Cultures were exposed to different concentrations of AngII (5x10‑11 to 5x10‑9 M). The incubation with hormones lasted 15 min to limit the genomic effects of steroids. In the phosphorylation reaction, we used γ32P‑ATP as a donor of phosphate and a synthetic peptide, Poly(Glu, Tyr) (4:1), as a substrate. The specific activities of PTKs were defined as pmol of 32P incorporated into 1 mg of exogenous Poly(Glu, Tyr) per minute (pmol/mg/min). Our findings suggest that testosterone and 17β‑estradiol may change the effects of angiotensins in a rapid non‑genomic way, probably via membrane‑located receptors. The most significant change was caused by testosterone, whose effect was most significant on changes caused by Ang1‑7. AngII‑induced changes in phosphorylation appeared to be insensitive to the presence of testosterone, but were modified by 17β‑estradiol.

A common effect of angiotensin II and relaxin 2 on the PNT1A normal prostate epithelial cell line

The prostate gland is a part of the male reproductive tract which produces both angiotensin II (Ang II) and relaxin 2 (RLN2). The present study analyzes the effect of both these peptide hormones at concentration 10(-8)M on viability, proliferation, adhesion, migration, and invasion of normal prostate epithelial cells (PNT1A). Improved survival in two- and three-dimensional cell cultures was noted as well as visual changes in colony size and structure in Geltrex™. Stimulatory influence on cell viability of each peptide applied single was lower than in combination. Enhanced survival of PNT1A cells appears to be associated with increased BCL2/BAX messenger RNA (mRNA) expression ratio. Modulation of cell spreading and cell-extracellular matrix adhesion dynamics were also altered as an influence of tested hormone application. However, long-term Ang II and RLN2 effects may lead to an increase of normal prostate cell migration and invasion abilities. Moreover, gelatin zymography revealed that both gelatinases A and B were augmented by Ang II treatment, whereas RLN2 significantly stimulated only MMP-9 secretion. These results support the hypothesis that deregulation of locally secreted peptide hormones such as Ang II and RLN2 may take part in the development of certain cancers, including prostate cancer. Moreover, the observed ability of relaxin 2 to act as a regulator of mRNA expression levels not only LGR7 but also classic angiotensin receptors suggested that renin-angiotensin system and relaxin family peptide system are functionally linked.

Angiotensin II regulates testicular peritubular cell function via AT1 receptor: a specific situation in male infertility

We observed that peritubular myoid cells in the human testis are immunoreactive for angiotensin II (AngII) receptors (AT1R) and explored AngII actions in cultured human testicular peritubular cells (HTPCs). In response to AngII they contracted within minutes. The AT1R-blocker losartan blocked contraction, implying involvement of AngII and AT1R in intratesticular sperm transport. AngII also significantly increased IL-6 mRNA levels and IL-6 secretion within hours and losartan again prevented this action. This suggests involvement in inflammatory processes, which may play a role in male infertility. AngII can be generated locally by mast cell (MC)-derived chymase (CHY), which cleaves AngI. In testicular biopsies from infertile men we found abundant MCs, which express CHY, within the wall of seminiferous tubules. In contrast, CHY-positive MCs are hardly found in normal human testis. Testicular inflammatory events may fuel processes resulting in impaired spermatogenesis. Therefore therapeutic interference with MCs, CHY or AT1R might be novel options in male infertility.

Expression and role of the angiotensin II AT2 receptor in human prostate tissue: in search of a new therapeutic option for prostate cancer

BACKGROUND

Evidence shows that angiotensin II type 1 receptor (AT1R) blockers may be associated with improved outcome in prostate cancer patients. It has been proposed that part of this effect could be due to angiotensin II type 2 receptor (AT2R) activation, the only active angiotensin II receptor in this situation. This study aimed to characterize the localization and expression of AT2R in prostate tissues and to assess its role on cell morphology and number in prostatic epithelial cells in primary culture.

METHODS

AT2R and its AT2R-interacting protein (ATIP) expression were assessed on non-tumoral and tumoral human prostate using tissue microarray immunohistochemistry, binding assay, and Western blotting. AT2R effect on cell number was measured in primary cultures of epithelial cells from non-tumoral human prostate.

RESULTS

AT2R was localized at the level of the acinar epithelial layer and its expression decreased in cancers with a Gleason score 6 or higher. In contrast, ATIP expression increased with cancer progression. Treatment of primary cell cultures from non-tumoral prostate tissues with C21/M024, a selective AT2R agonist, alone or in co-incubation with losartan, an AT1R antagonist, significantly decreased cell number compared to untreated cells.

CONCLUSIONS

AT2R and ATIP are present in non-tumoral human prostate tissues and differentially regulated according to Gleason score. The decrease in non-tumoral prostate cell number upon selective AT2R stimulation suggests that AT2R may have a protective role against prostate cancer development. Treatment with a selective AT2R agonist could represent a new approach for prostate cancer prevention or for patients on active surveillance.

Similarities and differences between effects of angiotensin III and angiotensin II on human prostate cancer cell migration and proliferation

Proliferation plays a critical role in tumor growth when cell migration is essential to invasion. The effect of Ang III and Ang II was evaluated on these important processes. Changes in the migration potential of prostate cancer cells were investigated using Wound Healing Test and a Transwell Migration Chamber with a 3 μm pore size. Cell proliferation was measured with a BrdU Assay and Countess Automated Cell Counter, thus determining the influence of angiotensins on hormone-dependent (LNCaP) and hormone-independent (DU-145) human prostate cancer lines. The influence of Ang III and Ang II on classic receptors may be inhibited by Losartan or PD123319. Test peptide modulation of the AT1 and AT2 receptors was examined by Western Blot and fluorescent immunocytochemistry. The results indicate that Ang III promotes the migration of both LNCaP and DU-145 lines, whereas Ang II stimulates this process only in androgen-independent cells. Both angiotensin peptides can induce prostate cancer cell proliferation in a time- and dose-dependent manner. The obtained results show that Ang III and Ang II can modify the expression of classic receptors, particularly AT2. These results suggest that the investigated peptide can modulate cell migration and proliferation in prostate cancer cells. Angiotensins probably have a greater influence on proliferation in the early-stage prostate cancer model than hormone-independent cell lines. Assume also that Ang II can enhance the migration tendency aggressive prostate cancer cells, while Ang III does so more effective in non-metastatic cells.

A comparison of the effects of Angiotensin IV on androgen-dependent and androgen-independent prostate cancer cell lines

INTRODUCTION

Angiotensin IV is one of the biologically active peptides of the renin-angiotensin system. Limited data suggests that this hexapeptide could contribute to cancer development and/or progression.

MATERIALS AND METHODS

Using the MTT reduction assay as an indicator of cell viability, and the bromodeoxyuridine incorporation assay as an indicator of cell proliferation, the influence of Angiotensin IV was evaluated on two human prostate cancer lines: androgen-dependent (LNCaP) and androgen-independent (DU-145). The potential effect of Angiotensin IV classic angiotensin receptors was examined by using the selective antagonists losartan and PD123319. Finally, the changes in expression levels of AT1 and AT2 receptors were compared, before and after angiotensin treatment.

RESULTS

Angiotensin IV caused significant changes in cell viability and proliferation in LNCaP cells but not in DU-145. It was found that AT2 receptor blocker (PD123319) was able to diminish the suppressor effect of Angiotensin IV on bromodeoxyuridine incorporation into the DNA of androgen-dependent prostate cancer cells. Simultaneously, it was reported that Angiotensin IV is the factor that modulates the density of AT1 and AT2 receptors in prostate cancer cells.

CONCLUSIONS

These findings suggested that Angiotensin IV can modulate tumour cell proliferation in the early stage of androgen-dependent prostate cancer. The effect might be promoted by the change of the angiotensin receptor level.

Immunohistochemical detection of angiotensin AT 1 and AT 2 receptors in prostate cancer

Introduction

The human prostate gland contains all the compounds of the renin-angiotensin system (RAS), including AT1 and AT2 angiotensin receptors. The role of local RAS in the prostate pathology is recently discussed. The aim of the present study was the evaluation of AT1 and AT2 expressions in human prostate cancers.

Material and methods

The investigation was performed in 20 paraffin-embedded needle biopsy specimens from routine diagnostic prostate cancer biopsies. The specimens were stained with hematoxylin and eosin and immunostained with anti-AT1 and anti-AT2 antibodies. For visualization of primary antibodies, the streptavidin-biotin-peroxidase technique was applied. The expression of both receptor proteins was evaluated quantitatively using image analysis method.

Results

The positive immunostaining with both anti- AT1 and anti-AT2 antibodies can be found in stromal as well as epithelial structures. The results of quantitative evaluation showed the positive correlation between AT1 and AT2 expressions in neoplastic epithelium and overexpression of both AT1 and AT2 in neoplastic epithelium of Gleason grade 2, but not in cancerous structures of Gleason grades 3-5.

Conclusions

The data on AT1 and AT2 receptor expressions may suggest the involvement of RAS in prostate cancerogenesis. Moreover, the persistence of AT1 receptors in prostate cancer speaks in favor of attempts to use of AT1 receptor blockers (i.e. sartanes) and/or AT2 agonists in prostate cancer prophylaxis and/or treatment.

Expression and function of ATIP/MTUS1 in human prostate cancer cell lines

BACKGROUND

We have previously demonstrated Ang II type 2 (AT(2)-) receptor-mediated inhibition of EGF-induced prostate cancer cell growth in androgen-dependent (LNCaP) and independent (PC3) prostate cancer cell lines.

METHODS

To explore the signaling pathways involved in this inhibitory effect, we examined the interaction of the AT(2)-receptor with its novel regulatory partner ATIP using real time PCR, over-expression, siRNA and [(3)H]thymidine incorporation assays.

RESULTS

The results in human prostate cancer cell lines demonstrate the presence of ATIP in both cell lines examined, and suggest that (i) the AT(2)-receptor through an interaction with ATIP mediates an anti-growth factor effect in both androgen-dependent and androgen-independent cell lines; (ii) ATIP expression decreases as the rate of cell growth and androgen-independence increase; and (iii) EGF may act on cell growth in part by reducing the content of ATIP present in the cells.

CONCLUSIONS

The results support our earlier proposal in normal cell lines that ATIP is an important component of the cellular response to AT(2)-receptor activation. The results further suggest that a critical level of ATIP is required to mediate the effect of AT(2)-receptor activation to inhibit EGF mediated increases in cell growth. They also suggest that EGF may in part induce cell growth by suppressing the level of ATIP expression.

Angiotensin-converting enzyme insertion/deletion and angiotensin type 1 receptor A1166C polymorphisms as genetic risk factors in benign prostatic hyperplasia and prostate cancer

INTRODUCTION

Prostate cancer is one of the most common malignant neoplasias in developed countries. In 2003, 6,536 new cases and 4,602 related deaths were reported in Mexico. The renin-angiotensin system has been shown to play a role in prostate cancer pathology. Two previous studies investigated the association of prostate cancer with the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene; both studies reported an association between prostate cancer and the DD genotype. The present study was aimed at searching for an association of prostate cancer and benign prostatic hyperplasia with the I/D polymorphism in the ACE gene and the A1166C polymorphism in the angiotensin type 1 receptor (AGT1R) gene and at comparing allele frequencies between both groups and the general population.

MATERIALS AND METHODS

DNA was extracted from 20 samples from individuals with a prostate cancer diagnosis and from 20 samples from individuals with a benign prostatic hyperplasia diagnosis. Genotyping was performed by PCR-RFLP analysis. Polymorphism frequency results obtained for the test groups were compared with the frequencies in 66 individuals from the general population, which were previously obtained at the same molecular medicine laboratory in the context of other studies.

RESULTS

The comparative analysis of the three groups revealed significant differences for allele frequencies in the two genes in patients groups (prostate cancer and benign prostatic hyperplasia) versus the general population. The D allele in the ACE gene was closely associated with a significant higher risk of developing both benign prostatic hyperplasia (odds ratio [OR]=21.87; 95% confidence interval [CI]=2.314-206.479) or prostate cancer (OR=31.66; 95% CI=0.091-1.272), and the AGT1R A1166 allele in the homozygote state was identified as a risk genotype for benign prostatic hyperplasia (OR=56.07).

CONCLUSIONS

Genotypes in ACE and AGT1R polymorphisms could be considered as genetic risk markers for benign prostatic hyperplasia or prostate cancer.

Role of the renin-angiotensin system in prostate cancer

Prostate cancer is highly prevalent in Western society, and its early stages can be controlled by androgen ablation therapy. However, the cancer eventually regresses to an androgen-independent state for which there is no effective treatment. The renin-angiotensin system (RAS), in particular the octapeptide angiotensin II, is now recognised to have important effects on growth factor signalling and cell growth in addition to its well known actions on blood pressure, fluid homeostasis and electrolyte balance. All components of the RAS have been recently identified in the prostate, consistent with the expression of a local RAS system in this tissue. This review focuses on the role of the RAS in the prostate, and the possibility that this pathway may be a potential therapeutic target for the treatment of prostate cancer and other prostatic diseases.

Functional angiotensin II type 2 receptors inhibit growth factor signaling in LNCaP and PC3 prostate cancer cell lines

BACKGROUND

There is clear evidence of a tissue-based renin-angiotensin system in the prostate and studies to date suggest that AT(1)-receptor blocking drugs inhibit the growth of some prostate cancer cell lines and delay the development of prostate cancer. The present studies examine the action of Ang II in two prostate cancer cell lines and report the presence of functional AT(2)-receptors that regulate the actions of growth factors.

METHODS

Immunohistochemistry was used to identify the presence of Ang II and QPCR techniques to examine AT(1)- and AT(2)-receptor mRNA expression in androgen-dependent (LNCaP) and independent (PC3) cell lines. The effects of AT(1)- and AT(2)-receptor activation upon EGF-induced DNA synthesis and ERK2 phosphorylation in these cells were also examined.

RESULTS

Functional AT(2)-receptors together with Ang II were identified in both cell lines and stimulation of these receptors inhibited EGF-induced DNA synthesis and ERK2 phosphorylation. AT(1)-receptors, although present in both cell lines, were only functional in LNCaP cells where activation stimulated DNA synthesis.

CONCLUSIONS

Functional AT(2)-receptors are present and have the capacity to inhibit EGF-induced prostate cancer cell growth in LNCaP and fast growing androgen-independent PC3 cell lines, whereas functional AT(1)-receptors are found only in LNCaP cells where their activation stimulates DNA synthesis.

Angiotensin II induces oxidative stress in prostate cancer

Angiotensin II has been shown to be a cytokine especially acting as a growth factor. A local renin-angiotensin system has been identified in the prostate gland, and the physiologic function of angiotensin II seems to be similar in prostate cancer, as we previously reported. In the present study, we explored the biological role of angiotensin II in oxidative stress of prostate cancer cells. Activated Akt was determined, and the expression of oxidative stress-related proteins (p47phox, manganese superoxide dismutase 2, glutathione peroxidase) was examined by Western blotting in LNCaP cells, which were stimulated with angiotensin II and/or an angiotensin II receptor type 1 blocker, candesartan. To examine DNA damage induced by angiotensin II, 8-hydroxy-2'-deoxyguanosine was determined, and Western blots were analyzed to detect checkpoint proteins including p53, Chk2, and cdc2. Immunocytochemical studies of inducible nitric oxide synthase and superoxide anion radical (O(2)(-)) were done in LNCaP cells stimulated with angiotensin II. The phosphorylation of Akt was induced by angiotensin II treatment and inhibited by candesartan, as well as by LY294002, an inhibitor of phosphoinositide 3-kinase. Oxidative stress-related proteins were up-regulated by angiotensin II and inhibited by pretreatment with candesartan or catalase. The level of 8-hydroxy-2'-deoxyguanosine was increased by angiotensin II and conversely decreased by candesartan. Immunocytochemical studies showed that angiotensin II enhanced an inflammatory marker, inducible nitric oxide synthase, and the production of O(2)(-) radical. The hypothesis that angiotensin II has the potential to induce oxidative stress, which may be implicated in carcinogenesis of the prostate gland through long-term exposure to chronic inflammation is proposed.

Male accessory glands of Drosophila melanogaster make a secreted angiotensin I-converting enzyme (ANCE), suggesting a role for the peptide-processing enzyme in seminal fluid

Angiotensin I-converting enzyme (ACE) expressed on the surface of endothelial cells is responsible for the last step in the synthesis of circulating angiotensin II and the inactivation of bradykinin. Mammalian ACE is also expressed in the prostate with other components of the renin-angiotensin system, and in developing spermatids, where the peptidase activity is known to be critical for normal sperm function. The importance of an ACE gene to male fertility has also been demonstrated in Drosophila melanogaster, where Ance is expressed in spermatids, and hypomorphic alleles of Ance cause a defect in spermiogenesis. Here we show that ANCE, which shares many enzymatic properties with mammalian ACE, is also a product of the male accessory gland of D. melanogaster. It is expressed in the secondary cells and is associated with the electron dense granule within the large vesicles of these cells. ACE proteolytic activity is lost from the accessory glands during mating, consistent with transfer to the mated female in the seminal fluid. The accessory gland ACE-like activity might have an evolutionarily conserved function processing biologically active peptides with a role in male fertility.

Immunohistochemical analysis of low-grade and high-grade prostate carcinoma: relative changes of parathyroid hormone-related protein and its parathyroid hormone 1 receptor, osteoprotegerin and receptor activator of nuclear factor-kB ligand

AIM

To investigate multiple bone cytokines produced by prostate carcinoma (PCa) as a novel strategy to differentiate potential aggressiveness in localised PCa using immunohistochemical analysis.

METHODS

A total of 47 cases of PCa undergoing radical prostatectomy or transurethral prostatic resection at our institution (Fundación Jiménez Díaz (Grupo Capio), Madrid, Spain) between January 1991 and June 1998 were identified as low-grade (< or =4; n = 22) or high-grade (> or =7, excluding 7 (3+4) cases; n = 25) PCa according to Gleason grade. PCa specimens were immunostained for: parathyroid hormone (PTH)-related protein (PTHrP), the PTH1 receptor, osteoprotegerin and receptor activator of nuclear factor-kappa B ligand (RANKL), as well as Ki67 (a proliferation marker) and CD34 (an angiogenesis marker).

RESULTS

PCa samples showed an increased immunostaining for both osteoprotegerin and RANKL, associated with tumour grade and PTHrP positivity, in the tumoral epithelium. Using a score value of 4-corresponding to moderate staining - as cut-off, the best sensitivity value was for PTHrP (with C-terminal antiserum C6; 100 %); wheras the best specificity value was for RANKL (95 %).

CONCLUSIONS

All the evaluated factors are overexpressed mainly in the high-grade tumours. Our findings indicate that, in most patients with PCa (with Ki67 values between 1% and 9%), sequential determination of C-terminal PTHrP and RANKL immunoreactivities is a useful approach to discriminate low-grade and high-grade tumours.

Renin-angiotensin system is an important factor in hormone refractory prostate cancer

BACKGROUND

The aim of this study was to perform a comprehensive evaluation of the renin-angiotensin system (RAS) in prostate cancer.

METHODS

We investigated the expression of RAS components in prostate cancer cells treated with hormonal agents. Real-time PCR data showed the expression of the AT1 receptor, angiotensin I converting enzyme (ACE), and angiotensin I/II (Ang-I/II) precursor in all 87 prostate tissue samples.

RESULTS

Expression of these genes in hormone refractory prostate cancer (HRPC) was significantly higher than that in normal prostate tissue and untreated prostate cancer tissue. Western blot showed that protein expression of the AT1 receptor and Ang-I/II was enhanced in LNCaP cells cultivated in steroid-free medium. When LNCaP cells were stimulated with dihydrotestosterone (DHT), estradiol (E2), dexamethasone (DEX), or anti-androgen drugs, protein expression of the AT1 receptor and Ang-I/II was augmented.

CONCLUSIONS

The present data suggest that prostatic RAS is overexpressed in HRPC tissue, and expression of its components is influenced by several kinds of hormonal stimulation.

Antiproliferative activity of angiotensin II receptor blocker through cross-talk between stromal and epithelial prostate cancer cells

We showed previously that angiotensin II activated the proliferation of prostate cancer cells and that angiotensin II receptor blockers (ARB) could inhibit it. Here, we investigated whether angiotensin II exerts mitogenic effects on the cross-talk between stromal and cancer cells and whether an ARB can inhibit tumor growth through actions on stromal cells. Cell proliferation and interleukin-6 secretion of prostate stromal PrSC cells stimulated with angiotensin II, tumor necrosis factor-alpha, or epidermal growth factor were examined in the absence and presence of ARB. We examined the effect of ARB on mitogen-activated protein kinase (MAPK) phosphorylation of PrSC and PC-3 cells treated with conditioned medium of PrSC cells and determined the effect of ARB on tumor growth induced by paracrine factors from PrSC cells. Angiotensin II activated the cell proliferation and interleukin-6 secretion of PrSC cells, and ARB inhibited it. Angiotensin II, tumor necrosis factor-alpha, or epidermal growth factor induced MAPK phosphorylation in PrSC cells, and this phosphorylation was inhibited by ARB. Conditioned medium of PrSC cells with angiotensin II activated MAPK phosphorylation in PC-3 cells, and ARB-treated conditioned medium of PrSC cells inhibited it. The tumor growth and angiogenesis of a mixture of PC-3 with PrSC were inhibited by ARB administration, whereas those of PC-3 xenografts were not inhibited. ARB exerted an antiproliferative effect on prostate cancer through paracrine factors from stromal cells. Because prostate stromal cells are thought to be involved in the initiation and development of prostate cancer, the present data suggest the possibility that ARBs are a novel therapeutic class of agents for prostate cancer.