Induction of prostate apoptosis by doxazosin in benign prostatic hyperplasia

Alpha1-adrenergic receptor antagonists: novel therapy for pituitary adenomas

Pituitary tumors are common and cause considerable morbidity due to local invasion and altered hormone secretion. Doxazosin (dox), a selective alpha(1)-adrenergic receptor antagonist, used to treat hypertension, also inhibits prostate cancer cell proliferation. We examined the effects of dox on murine and human pituitary tumor cell proliferation in vitro and in vivo. dox treatment inhibited proliferation of murine pituitary tumor cells, induced G(0)-G(1) cell cycle arrest, and reduced phosphorylated retinoblastoma levels. In addition, increased annexin-fluorescein isothiocyanate immunoreactivity and cleaved caspase-3 levels, in keeping with dox-mediated apoptosis, were observed in the human and murine pituitary tumor cells, and dox administration to mice, harboring corticotroph tumors, decreased tumor growth and reduced plasma ACTH levels. dox-mediated antiproliferative and proapoptotic actions were not confined to alpha-adrenergic receptor-expressing pituitary tumor cells and were unaffected by cotreatment with the alpha-adrenergic receptor blocker, phenoxybenzamine. dox treatment led to reduced phosphorylated inhibitory kappaB (IkappaB)-alpha expression, and nuclear factor-kappaB transcription and decreased basal and TNFalpha-induced proopiomelanocortin transcriptional activation. These results demonstrate that the selective alpha(1)-adrenergic receptor antagonist dox inhibits pituitary tumor cell growth in vitro and in vivo by mechanisms that are in part independent of its alpha-adrenergic receptor-blocking actions and involve down-regulation of nuclear factor-kappaB signaling. dox is proposed as a possible novel medical therapy for pituitary tumors.

BENIGN PROSTATIC HYPERPLASIA CELL LINE VIABILITY AND MODULATION OF JM-27 BY DOXAZOSIN AND IBUPROFEN

PURPOSE

Benign prostatic hyperplasia (BPH) is among the most common diseases affecting quality of life in older men. Despise intense research efforts to our knowledge the genetic mechanisms underlying the BPH disease process and therapeutic markers needed to determine patient responsiveness to a particular form of pharmacological therapy are still not identified. This has slowed the development of new therapeutic agents for the treatment of BPH.

MATERIALS AND METHODS

We investigated the cellular effects of certain drugs on BPH. Besides doxazosin, which is the prevailing drug to treat BPH, the effect of ibuprofen was examined as a new therapeutic approach due to strong evidence of a correlation between BPH and inflammation.

RESULTS

This study showed that doxazosin as well as ibuprofen significantly decreases cell viability and induced apoptosis in 267 B1 cells as well as in BPH-1 cells. In addition, we observed that the administration of doxazosin and ibuprofen to BPH-1 cells decreased the expression of JM-27, a protein particularly expressed in prostate that is highly up-regulated in symptomatic BPH.

CONCLUSIONS

Our findings suggest that ibuprofen may be a new therapeutic target for the treatment of BPH. Further research must be done to investigate the potential use of ibuprofen in patients with BPH and examine if JM-27 expression in patients with BPH may stratify individuals who may be most responsive to pharmacological treatment.

Doxazosin inhibits human vascular endothelial cell adhesion, migration, and invasion

The quinazoline-derived alpha1-adrenoceptor antagonists, doxazosin and terazosin have been recently shown to induce an anoikis effect in human prostate cancer cells and to suppress prostate tumor vascularity in clinical specimens [Keledjian and Kyprianou, 2003]. This study sought to examine the ability of doxazosin to affect the growth of human vascular endothelial cells and to modulate vascular endothelial growth factor (VEGF)-mediated angiogenesis. Human umbilical vein endothelial cells (HUVECs) were used as an in vitro model to determine the effect of doxazosin on cell growth, apoptosis, adhesion, migration, and angiogenic response of endothelial cells. The effect of doxazosin on cell viability and apoptosis induction of human endothelial cells, was evaluated on the basis of trypan blue and Hoechst 33342 staining, respectively. Doxazosin antagonized the VEGF-mediated angiogenic response of HUVEC cells, by abrogating cell adhesion to fibronectin and collagen-coated surfaces and inhibiting cell migration, via a potential downregulation of VEGF expression. Furthermore there was a significant suppression of in vitro angiogenesis by doxazosin on the basis of VEGF-mediated endothelial tube formation (P < 0.01). Fibroblast growth factor-2 (FGF-2) significantly enhanced HUVEC cell tube formation (P < 0.01) and this effect was suppressed by doxazosin. These findings provide new insight into the ability of doxazosin to suppress the growth and angiogenic response of human endothelial cells by interfering with VEGF and FGF-2 action. This evidence may have potential therapeutic significance in using this quinazoline-based compound as an antiangiogenic agent for the treatment of advanced prostate cancer.

After ALLHAT: doxazosin for the treatment of benign prostatic hyperplasia

Doxazosin mesylate is an alpha1-adrenoceptor antagonist that was used to treat hypertension until a major study (ALLHAT; Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial) showed that it increased the risk of progressing to heart failure. Doxazosin is now being used to treat benign prostatic hyperplasia (BPH). Noradrenaline acts on alpha1-adrenoceptors to contract the smooth muscle in the prostate and bladder, and by opposing these actions, doxazosin is beneficial in BPH. Doxazosin also increases apoptosis in the prostate. Although the standard preparation is suitable for once-daily dosing in BPH, it has to be titrated through three steps to its final dose. The controlled-release gastrointestinal therapeutic system (GITS) formulation of doxazosin is more convenient to use as it only has to be titrated through one step. In the treatment of BPH, standard doxazosin reduced both obstructive and irritative symptoms and increased peak urinary flow rate. The main side effects with doxazosin are those commonly associated with lowering blood pressure, although doxazosin lowers blood pressure to a lesser extent in normotensives than hypertensives. There is some evidence that in addition to being easier to use, doxazosin GITS may cause less adverse effects than the standard preparations. The benefits of doxazosin and the 5alpha-reductase inhibitor, finasteride, may be additive in BPH especially in men with large prostates. Further trials are necessary in order to determine whether doxazosin GITS is superior to other alpha1-adrenoceptor antagonists in BPH.

SERENOA REPENS TREATMENT MODIFIES BAX/BCL-2 INDEX EXPRESSION AND CASPASE-3 ACTIVITY IN PROSTATIC TISSUE FROM PATIENTS WITH BENIGN PROSTATIC HYPERPLASIA

PURPOSE

Permixon is a lipidosterolic extract of Serenoa repens (SR) widely used to treat men with benign prostatic hyperplasia (BPH). We tested the effect of this drug on molecular mechanisms associated with apoptosis, such as the Bax-to-Bcl-2 expression ratio and caspase-3 activity, in prostatic tissue from men with symptomatic BPH treated for 3 months before surgery.

MATERIALS AND METHODS

An open, multicenter pilot study of 2 parallel groups of patients with BPH was done. They were randomized to be followed for 3 weeks without any treatment before surgery (control group) or to receive 160 mg SR orally twice daily for a 3-month period preceding the same surgery. Surgery was ultimately performed in 17 controls and 12 patients by transurethral prostate resection or retropubic adenomectomy. Bax and Bcl-2 expression, and caspase-3 activity were determined by Western blot in 15 controls and 10 patients, and reported in blinded fashion.

RESULTS

The Bax-to-Bcl-2 ratio, which is used as an apoptotic index, was significantly increased in the prostatic tissue of treated patients. The level of the intact 116 kDa poly (adenosine diphosphate-ribose) polymerase form, an enzyme involved in the cell death apoptotic pathway, was also found to be decreased in prostatic tissue from SR treated patients, suggesting increased caspase 3 activity in the prostate.

CONCLUSIONS

Permixon increased molecular markers involved in the apoptotic process, ie the Bax-to-Bcl-2 expression ratio and caspase-3 activity. This could have clinical relevance due to the improvement in symptoms produced by treatment with this drug.

The role of alpha-blockers in the management of prostate cancer

Prostate cancer is the second most common cause of cancer death in men in the US. Patients with prostate cancer are initially treated with surgical resection, radiation or antiandrogen therapy. After an initial remission, however, the majority of prostate tumours evolve into a highly aggressive, metastatic androgen-independent state, for which successful therapy has not yet been established. During the past few years, new perspectives have emerged towards the development of preventive and therapeutic approaches for prostate cancer. Quinazoline-based alpha(1)-blockers have been shown to have antitumour efficacy against prostate cancer cells in inducing apoptosis and anoikis via an alpha(1)-adrenoceptor-independent mechanism. Specifically, doxazosin and terazosin can induce apoptosis, inhibit invasion and migration of prostate cancer and endothelial cells, and reduce their adhesion potential to extracellular matrix components, thus enhancing their susceptibility to anoikis. This review discusses recent evidence suggesting the apoptotic efficacy of quinazoline-based alpha(1)-adrenoceptor antagonists, doxazosin and terazosin and speculates on the therapeutic promise of these drugs as novel antitumour agents against prostate cancer. From a drug discovery perspective, separation of the effect of doxazosin on apoptosis in prostate cancer cells from its original pharmacological activity in normal prostate cells, will provide a molecular basis in developing a novel class of apoptosis-inducing agents through lead optimisation.

INHIBITION OF MITOGENIC SIGNALING AND INDUCTION OF APOPTOSIS IN HUMAN BLADDER SMOOTH MUSCLE CELLS TREATED WITH DOXAZOSIN

PURPOSE

The alpha1 antagonist doxazosin is used to treat lower urinary tract symptoms and is believed to function primarily as a smooth muscle relaxant. However, doxazosin has been shown to inhibit proliferation and induce apoptosis in nonbladder smooth muscle. Consequently, we examined the effects of doxazosin on human bladder smooth muscle cell (SMC) proliferation and apoptosis.

MATERIALS AND METHODS

Primary human bladder SMCs were cultured in M199 with 10% fetal bovine serum (FBS) until they reached 65% confluency and then they were made quiescent by serum starvation in M199 with 0.4% FBS for 24 hours. The quiescent bladder SMCs were pretreated for 30 minutes with doxazosin or vehicle (dimethyl sulfoxide) and then stimulated with 10% FBS for 24 hours. Measurement of 5'-bromo-2'-deoxyuridine (BrdU) uptake by flow cytometry was used to determine the effect of doxazosin on cell cycle progression. Western immunoblot was used to examine cell cycle protein expression and phosphorylation of the retinoblastoma protein (Rb) and cyclin A, both of which regulate cell cycle progression.

RESULTS

Cellular proliferation was inhibited in a dose dependent manner by doxazosin. There was nearly a 50% decrease in BrdU uptake at 10 microM doxazosin and an approximately 90% decrease in BrdU at 25 microM doxazosin. Notably, doxazosin inhibited phosphorylation of Rb and expression of cyclin A, both of which are necessary for cell cycle progression. At concentrations of 25 microM doxazosin or greater apoptosis was induced in the bladder SMCs, as indicated by an increase in subG1 DNA content.

CONCLUSIONS

Our study demonstrates that doxazosin inhibits mitogen induced proliferation of human bladder SMC by blocking cell cycle progression at the of G1/S border. Doxazosin induced cell cycle inhibition appears to be at least in part due to an inhibition of mitogen induced Rb phosphorylation and cyclin A expression. At higher concentrations doxazosin induces apoptosis in human bladder SMCs.

Abnormalities of apoptotic and cell cycle regulatory proteins in distinct histopathologic components of benign prostatic hyperplasia

INTRODUCTION

Benign prostatic hyperplasia (BPH) is a slowly progressive abnormal glandular enlargement with heterogeneous morphology. Disruption of apoptotic pathways has been suggested as an important regulatory mechanism in this common and significantly morbid disease.

METHODS

Prostatic tissue from 20 patients with BPH and no prior or subsequent prostatic carcinoma was obtained by transurethral prostatectomy (TURP) at the University of California Davis. Apoptotic regulatory proteins: BCL2, BAX and p27 were analyzed by immunohistochemistry and evaluated for expression in four distinct histologic patterns: hyperplastic epithelium, nodules, dilated glands and atrophic/inflammatory glands.

RESULTS

Particularly striking was the decreased expression of BAX and an abnormal BCL2 : BAX ratio within all nodules relative to expression in other epithelial patterns. p27 expression was decreased in 35% of the hyperplastic epithelial areas and 10% of the nodules.

DISCUSSION

Overall, abnormal expression of BCL2, BAX and/or p27 was identified in the hyperplastic epithelium of 19 (90%) of specimens and all 12 (100%) of the hyperplastic nodules. The high frequency of abnormalities in apoptosis regulatory genes, suggests that alteration of apoptotic pathways is important for the development of this condition.

Induction of anoikis by doxazosin in prostate cancer cells is associated with activation of caspase-3 and a reduction of focal adhesion kinase

The quinazoline family of alpha1-blockers (prazosin, doxazosin, and terazosin) induce apoptosis of prostate cells through an alpha1-adrenoceptor-independent mechanism. The objective of this study was to gain insight into the non-adrenergic, apoptotic mechanism of action of doxazosin in the prostate and the induction of anoikis by doxazosin. Primary cultures of benign prostate stromal and epithelial cells and the LNCaP (androgen sensitive) and PC-3 (androgen insensitive) prostate carcinoma cell lines were treated with doxazosin (0-50 microM). The effects of doxazosin on cell morphology, caspase-3 activity, and the expression levels of focal adhesion kinase (FAK) and integrin-linked kinase (ILK) were examined. Doxazosin induced changes in morphology consistent with anoikis in both benign and cancerous prostatic cells and increased caspase-3 activity. The effects were similar comparing benign cells (which express alpha1-adrenoceptors) and cancer cells (which do not express alpha1-adrenoceptors), but were more robust in benign cells. Norepinephrine had no effect on doxazosin-induced cell morphology or caspase-3 activity. Treatment of PC-3 cells with doxazosin significantly reduced the protein levels of FAK but did not significantly affect the levels of ILK. These findings suggest that doxazosin induces apoptosis and anoikis of prostate cancer cells by a mechanism of action that is alpha1-adrenoceptor independent. The apoptosis of cancer cells induced by doxazosin counteracts cell proliferation and may have the potential of retarding or reversing prostate cancer cell growth.

Apoptotic impact of alpha1-blockers on prostate cancer growth: a myth or an inviting reality?

BACKGROUND

Pharmacological manipulation or genetic targeting of the major apoptosis regulators, such as bcl-2, caspases, and inhibitors of apoptosis (IAPs), represent clinically attractive avenues towards effective therapeutic strategies for advanced prostate cancer. A wealth of evidence established the alpha(1)-adrenoceptor antagonists to be clinically effective in relieving the symptoms associated with benign prostatic hyperplasia (BPH) by relaxing prostatic smooth muscle tone. This action alone however does not fully account for the long-term clinical response to these drugs in BPH patients.

METHODS

Experimental and retrospective clinical studies provided new evidence supporting a differential growth-suppressing function of two alpha(1)-adrenoceptor antagonists against prostate cancer, independent of an alpha(1)-adrenoceptor mechanism.

RESULTS

The quinazoline-based antagonists, doxazosin and terazosin, induce apoptosis, inhibit cell adhesion to the extracellular matrix (by activating anoikis), and prevent cell invasion and migration of prostate tumor epithelial cells and vascular endothelial cells. Tamsulosin, a sulphonamide-based, clinically effective alpha(1)-adrenoceptor antagonist for BPH treatment, fails to exert a similar apoptotic action against prostate cells. Furthermore, at pharmacologically relevant doses, doxazosin suppresses benign and malignant prostate growth in in vivo experimental models. The effect is characterized by three intriguing features: (a) it is mediated by an alpha(1)-adrenoceptor-independent action, (possibly related to the quinazoline nucleus); (b) it is targeted at the apoptotic process without affecting cell proliferation; and (c) the elevated apoptotic index correlated with symptom score improvement in BPH patients.

CONCLUSIONS

This evidence challenges conventional knowledge of the mechanism of action of alpha(1)-adrenoceptor antagonists, and points to a new therapeutic value for these drugs by providing a differential molecular basis for their anti-tumor efficacy. The present review focuses on the characterization of the apoptotic/anti-angiogenic effect of quinazoline-based alpha(1)-adrenoceptor antagonists against prostate cancer cells and discusses the clinical significance of this action in the prevention and treatment of prostate cancer.

Doxazosin controlled release vs tamsulosin in the management of benign prostatic hyperplasia: an efficacy analysis

An analysis is presented to compare the efficacies of the doxazosin gastrointestinal therapeutic system (doxazosin-GITS) and tamsulosin in patients with benign prostatic hyperplasia (BPH), collecting data from a published 20-week, randomized, double-blind, crossover study. Results demonstrated that after 8 weeks of treatment, both doxazosin-GITS and tamsulosin provided significant (p < 0.001) improvement from baseline in total international prostate symptom score (IPSS) and obstructive and irritative subscores. Doxazosin-GITS was more effective than tamsulosin (p = 0.019 between-group difference for total IPSS; p = 0.001 for irritative subscore). Similarly, after the first 4 weeks of treatment, prior to dose titration, both doxazosin-GITS and tamsulosin provided significant (p < or = 0.001) improvement in total IPSS and subscores. Doxazosin-GITS was more effective than tamsulosin (p = 0.045 between-group difference for obstructive subscore). These data confirm that the efficacy of doxazosin is superior to that of tamsulosin in the management of patients with BPH.

Benign prostatic hyperplasia

In both ageing men and women, there is an increasing incidence of lower urinary tract symptoms (LUTS) which are increasing. These infections have many possible causes, including smooth muscle dysfunction, neurological factors and benign prostatic hyperplasia. Up to 15% to 25% of men aged 50-65 years have LUTS of sufficient severity to interfere with their quality of life. Although benign prostatic hyperplasia is an important cause of these symptoms, and can have serious consequences, clinicians should be aware of these other causes so that the appropriate diagnosis is made before invasive treatments are started. New medical treatments, including alpha-adrenergic blocking agents and 5 alpha-reductase inhibitors mean that many men without complications such as infection, bleeding, or chronic retention, and with mild to moderate symptoms, should be managed in primary care. Combined local protocols between primary and secondary care will help to establish which men with persistent symptoms or complications need referral for a urological opinion to determine the need for further investigation and more invasive forms of management. We review the pathophysiology of the disease, and current approaches to investigation and management of this common problem.

Induction of prostate apoptosis by alpha1-adrenoceptor antagonists: mechanistic significance of the quinazoline component

alpha(1)-Adrenoceptor antagonists, have been documented to induce apoptosis and reduce prostate tumor vascularity in benign and malignant prostate cells. The quinazoline based alpha(1)-antagonists, doxazosin and terazosin but not tamsulosin (a sulphonamide derivative) suppress prostate growth without affecting cell proliferation. These quinazoline-mediated apoptotic effects occur via an alpha(1)-adrenoceptor independent mechanism potentially involving activation of the TGF-beta signal transduction pathway. This review discusses the current knowledge of the action of quinazoline-derived alpha(1)-adrenoceptor antagonists in the benign and malignant prostate and their potential therapeutic use in the treatment of benign prostatic hyperplasia (BPH) and prostate cancer. Finally, a molecular pathway is proposed for their observed apoptotic function against prostate cells. Increased understanding of the action of these established and clinically accepted agents would provide a basis for the design of safe, effective therapeutic regimens in the treatment of prostatic diseases.

Doxazosin and terazosin suppress prostate growth by inducing apoptosis: clinical significance

PURPOSE

Doxazosin and terazosin are known to relax prostate smooth muscle through blockade of alpha 1-adrenergic innervation to the prostate. This action alone however does not fully account for the long-term clinical responses exerted by these drugs in the treatment of patients with benign prostatic hyperplasia (BPH).

MATERIALS AND METHODS

Experimental and clinical studies were done to establish the induction of prostate cell apoptosis by alpha 1-adrenoceptor antagonists as a molecular mechanism contributing to their long-term efficacy in the management of lower urinary tract symptoms associated with BPH and to potential suppression of prostate cancer growth.

RESULTS

The data indicate that both doxazosin and terazosin induce apoptosis in prostate cancer cells in vitro and in vivo. The apoptotic effect of doxazosin and terazosin is mediated by a mechanism independent of the alpha1-adrenoceptor blockade, potentially under the direction of the quinazoline nucleus, since the nonquinazoline alpha 1-adrenoceptor antagonist tamsulosin does not elicit an apoptotic response. Recent experimental evidence points to deregulation of signal transduction pathways involving transforming growth factor-beta and disruption of cell attachment to the extracellular matrix (anoikis) as potential mechanisms underlying this apoptotic action of quinazoline based alpha 1-adrenoceptor antagonists against prostate cells.

CONCLUSIONS

The correlation of induced prostate smooth muscle cell apoptosis with improvement of urinary symptoms in patients with BPH treated with doxazosin and terazosin, identifies apoptosis as an additional molecular mechanism for the long term therapeutic impact of these drugs in BPH. Moreover, the apoptotic effect elicited by quinazolines may have high clinical significance in the prevention and treatment of prostate cancer.

Effect of terazosin on clinical benign prostatic hyperplasia in older adults

PURPOSE

The objective of this meta-analysis of randomized controlled trials (RCTs) of terazosin versus placebo in men with benign prostatic hyperplasia (BPH) was to evaluate the effect of terazosin on lower urinary tract symptoms.

BACKGROUND

BPH is common in older men; more than 90% of men aged 70 and older suffer from BPH. (1,2) BPH has substantial negative effect on quality of life, with symptoms that interfere with activities of daily living. (3) The symptoms of BPH are primarily due to bladder outlet obstruction and are caused by dynamic prostatic smooth muscle tone and static prostatic obstruction. (4,5) The smooth muscle tone is dependent on the degree of the alpha-1 adrenergic receptors present in the bladder neck, prostrate capsule, and prostrate gland. The blockade of alpha-1 receptors with drugs such as terazosin reduces bladder outlet obstruction by reducing the smooth muscle tone. STUDY SELECTION AND DATA SOURCES: Selected studies were all RCTs of terazosin with two primary end points, namely, changes in the peak urinary flow rates and urinary symptom scores from baseline. Nine studies were selected using a Medline search, the details of which were not provided. The studies were conducted in North America and Europe between 1992 and 1996. Two of the studies included unpublished data that were obtained from Abbott Laboratories, which is the manufacturer of terazosin (Hytrin). The company also provided data on the other seven studies.

DATA EXTRACTION

The meta-analysis did not provide details of the data abstraction process. Urinary symptom score was measured using two different tools: the Boyarsky Symptom Index (BSI) and American Urology Association Symptom Index (AUA-SI). The BSI was used in seven studies and AUA-SI in two studies. The authors calculated a common symptom score, based on the common items from both questionnaires, that had all but one item used in the AUA-SI. Questions from AUA-SI are scored on a 0 to 5 scale and those on BSI on a 0 to 3 scale. To adjust for this difference, the authors performed a nonlinear rescaling of the AUA-SI to adjust for these scoring differences.

MAIN RESULTS

The ages of the patients (N = 3,948) ranged from 62 to 66. The duration of the studies varied from 8 to 52 weeks. Four of the studies used fixed dosages, and the rest used titration-to-response doses. The effect of terazosin versus placebo on peak urinary flow rate was similar in all the studies. The estimated mean increase in peak urinary flow rate was 1.39 mL/s greater in men receiving terazosin than in those receiving placebo, and the improvements were observed within 8 weeks of therapy. However, the changes in the symptom scores varied across the studies. Patients treated with terazosin had an estimated 1.9-point reduction (95% confidence interval (CI) = 1.6-2.3) in BSI and 3.5-point reduction (95% confidence interval (CI) = 2.8-4.1) in AUA-SI score from baseline. Improvements in scores were greater in studies that were conducted for longer duration.

CONCLUSIONS

The authors concluded that treatment with terazosin was associated with greater peak urinary flow rate and lower symptom score than treatment with placebo. There was no variability of efficacy of terazosin as a result of prostrate volume, and measurement of prostrate volume was not essential before initiation of therapy.

Anoikis induction by quinazoline based alpha 1-adrenoceptor antagonists in prostate cancer cells: antagonistic effect of bcl-2

PURPOSE

The ability of the quinazoline derived alpha1-adrenoceptor antagonists doxazosin and terazosin to induce apoptosis in benign and malignant prostate cells has been established. In this study we investigated the effect of the 2 piperazidinyl quinazoline based alpha1-adrenoceptor antagonists and the methoxybenzene sulfonamide alpha1-antagonist tamsulosin on human prostate cancer cell adhesion.

MATERIALS AND METHODS

Androgen independent PC-3 prostate cancer cells and PC-3 transfectant clones over expressing the apoptosis suppressor bcl-2 were used as an in vitro model. Cells were treated with pharmacologically relevant doses of 1 of the 3 alpha1-adrenoceptor antagonists and the effect on cell viability/cell adhesion on various substrates was examined. Analysis of expression of key attachment factors, such as vascular endothelial growth factor (VEGF) and hypoxia inducible factor-alpha, was performed.

RESULTS

Our results indicate a significant decrease in prostate cancer cell adhesion to gelatin and collagen but not to fibronectin in prostate cancer cells treated with doxazosin or terazosin (25 microM.) compared with untreated control cultures (p <0.05). In contrast, tamsulosin had no effect on prostate cancer cell adhesion. The 2 quinazolines doxazosin and terazosin but not tamsulosin had a significant inhibitory effect on prostate tumor cell invasion. In bcl-2 over expressing prostate cancer cells there was significant suppression of doxazosin induced anoikis and cell invasion compared with neocontrol transfectants (p <0.05). Doxazosin resulted in transient down-regulation (2-fold decrease) of VEGF at the mRNA and protein levels, as detected by reverse transcriptase-polymerase chain reaction and Western blotting, respectively. No significant changes in the expression profile of hypoxia inducible factor-1 alpha were observed after treatment with quinazolines. Furthermore, bcl-2 resulted in partial reversion of the doxazosin induced VEGF decrease.

CONCLUSIONS

These findings demonstrate that the quinazoline derived alpha1-antagonists doxazosin and terazosin but not sulfonamide based tamsulosin induce anoikis and inhibit prostate cancer cell invasion, an effect that is antagonized by bcl-2. This molecular basis of an alpha1-adrenoceptor independent action against prostate cancer cells by the quinazolines may have potential therapeutic significance in prostate cancer.

Quantitation of apoptotic activity following castration in human prostatic tissue in vivo

BACKGROUND

Androgen deprivation induces apoptosis in the prostate. Representative data, quantitating apoptotic activity in human prostatic epithelium following androgen ablation, are lacking.

METHODS

Human prostatic tissue was grafted beneath the renal capsule of intact male athymic mice and allowed to become established. The mice were castrated and specimens were harvested on post-castration day 0, 1, 2, 3, 4, 5, 7, 8, 9, 10, 14, 17, 18, and 21. Tissue was immediately fixed and apoptotic epithelial nuclei were identified.

RESULTS

The percentage of terminal deoxynucleotidyl-transferase-mediated dUTP nick end-labeling (TUNEL) positive epithelial cells increased from a baseline of 0.026%, peaked on post-castration day 3 (1.54%), and returned to baseline by day 21. Mathematical analysis predicted that the observed apoptotic activity account for the loss of 87% of prostatic epithelial cells in 3 weeks.

CONCLUSIONS

Post-castration apoptosis in human prostatic epithelium was low but was sufficient to account for the loss of nearly 90% of epithelial cells.

Effect of doxazosin on stretch-activated adenosine triphosphate release in bladder urothelial cells from patients with benign prostatic hyperplasia

OBJECTIVES

Recent data suggest that the bladder urothelium may have a sensory function by way of release of adenosine triphosphate (ATP) during stretch, which then acts as a sensory neurotransmitter. Because benign prostatic hyperplasia (BPH) can give rise to irritative (hypersensory) voiding patterns, we questioned whether the bladder urothelium from patients with BPH released more ATP during in vitro stretch and whether doxazosin, an alpha(1)-adrenoceptor blocker, affects this purinergic mechanism.

METHODS

Bladder urothelial biopsies from patients with BPH (n = 4) and controls (n = 4) were cultured using established techniques. In vitro stretch was performed with a Flexcell 2000 device that uses vacuum to deform the cell growth surface to impart a stretch force. Doxazosin (5 microM and 20 microM) was added to cells, and supernatants were collected at various points for ATP assay. ATP was assayed using the luciferin-luciferase reaction. ATP data were normalized to the time 0 value and expressed as a percentage of the baseline value.

RESULTS

After 96 hours of stretch, the BPH urothelial cells released significantly more ATP than did the control urothelial cells (62.6% +/- 11.2% versus 24.2% +/- 5.4%, P = 0.005) and nonstretched BPH urothelial cells (62.6% +/- 11.2% versus 15.1% +/- 5.1%, P = 0.004). The augmented release of ATP by stretched BPH bladder urothelial cells was completely blocked by treatment with 20 microM doxazosin.

CONCLUSIONS

Irritative voiding secondary to BPH may arise from increased ATP release by bladder urothelium during stretch. Doxazosin inhibits ATP release by way of an unknown mechanism that may or may not involve the alpha1-adrenoreceptor. Treatment for hypersensory voiding symptoms secondary to BPH might also target the urothelial purinergic pathway.

Effect of doxazosin on rat urinary bladder function after partial outlet obstruction

Hypoxia induced by partial outlet obstruction is believed to play a major role in both the hypertrophic and degenerative effects of partial outlet obstruction. Doxazosin (dox) is a clinically effective alpha-adrenergic antagonist used in the treatment of symptomatic benign prostatic hyperplasia (BPH). Although the major therapeutic effect of the agent is believed to occur on the smooth muscle components of the prostate by reducing prostatic urethral resistance and thus improving emptying, dox may have part of its clinical action via effects mediated by other actions, including via spinal alpha-adrenergic receptors or direct effects on the bladder, possibly via inhibition of vascular alpha receptors. The specific aim of the current study was to determine whether dox pretreatment on rats affects blood flow to the bladder and reduces the level of bladder dysfunction induced by partial outlet obstruction. In part 1, eight rats were separated into two groups of four rats each. Group 1 received oral administration of dox (30 mg/kg) for 4 weeks; group 2 received vehicle (5% dimethyl sulfoxide). After 4 weeks of treatment, blood flow studies were performed using fluorescent microspheres and the bladders excised, frozen, and submitted to Interactive Medical Technologies (IMT) for blood flow analysis. In part 2, 32 adult male rats were separated into four groups of eight rats each. Groups 1 and 2 received oral administration of dox (30 mg/kg) for 4 weeks, groups 3 and 4 received vehicle (5% dimethyl sulfoxide). At 4 weeks, the rats in groups 1 and 3 received partial outlet obstructions and treatment continued for an additional 2 weeks. After 6 weeks of treatment (total), each rat was anesthetized, the bladder excised, weighed, and isolated strips mounted and contractility studies performed. 1) Four weeks pretreatment of rats with dox increased blood flow to the bladder in both the control and obstructed groups. 2) Partial outlet obstruction induced a mild decrease in blood flow. 3) The magnitude of the increased bladder weight in the vehicle-treated obstructed group was significantly greater than in the dox-treated obstructed group. 4) Partial outlet obstruction resulted in significant decreases in the contractile response to field stimulation in both treated and non-treated rats. The magnitude of the decreased response was significantly greater in the non-treated rats. 5) The response to potassium chloride was significantly reduced by partial outlet obstruction in the vehicle-treated group but not in the dox-treated group. 6) The time to maximal tension was significantly increased in response to carbachol, adenosine triphosphate, and potassium chloride. However, the magnitude of the increase was significantly greater for the vehicle-treated obstructed groups stimulated by potassium chloride than for the dox-treated groups. Dox treatment of rats increased blood flow to the bladder and reduced the severity of the response to partial outlet obstruction. These beneficial effects would be due to pharmacological effects on alpha-adrenergic systems outside those present in the prostate. These include effects on blood flow to the bladder, effects on the micturition centers of the central nervous system, spinal reflexes, and alpha-adrenergic receptors in the urethra and bladder.

Terazosin, doxazosin, and prazosin: current clinical experience

Lower urinary tract symptoms (LUTS) suggestive of benign prostatic obstruction are common in aging men. Nearly 25% of men >40 years of age have LUTS. Medical therapy with alpha-blockade is the most common method of medical therapy for benign prostatic obstruction. Multiple methods of minimally invasive surgical therapies have been introduced in the last decade. These methods include balloon dilatation, temporary and permanent urethral stents, various laser techniques, microwave thermotherapy, transurethral needle ablation, electrovaporization, and high-intensity focused ultrasound. alpha-Receptor blockers to reduce the sympathetic tone of the prostate are considered as first-line therapy to relieve the symptoms of benign prostatic hyperplasia. Selective alpha(1)-receptor blockers relax prostatic smooth muscle, relieve bladder outlet obstruction, and enhance urine flow with fewer side effects. In addition, it was determined that treating patients with alpha-blockers increases prostatic apoptosis. Pharmacokinetic activity, mode of action, clinical efficacy, and side effects of the selective alpha(1)-receptor blockers terazosin, doxazosin, and prazosin are reviewed.

Meta-analysis of randomized trials of terazosin in the treatment of benign prostatic hyperplasia

OBJECTIVES

To determine the effectiveness of the long-acting alpha(1)-adrenergic receptor blocking agent terazosin compared with placebo on lower urinary tract symptoms and peak urinary flow rate in men with clinical benign prostatic hyperplasia.

METHODS

A formal meta-analysis of all nine randomized trials of terazosin using both an Empirical Bayes and a fully Bayesian approach was conducted. A pooled analysis was conducted on those studies in which patients had a baseline assessment of prostate volume by transrectal ultrasonography.

RESULTS

No evidence of heterogeneity was found in the estimated effects of terazosin on the change in peak flow rates in the studies. Terazosin treatment was associated with an increase in the peak flow rate of 1.4 mL/s (95% confidence interval [1.0, 1.7]) compared with placebo. Terazosin resulted in an average reduction of 2.2 points over placebo (95% confidence interval [1.6, 3.0]) regarding the common symptom score (range 0 to 36 points). A mild heterogeneity was found across the studies, with the decrease in symptom score slightly greater with longer treatment duration. No evidence was found that the baseline prostate volume influenced the effect of terazosin.

CONCLUSIONS

Terazosin was effective and superior to placebo in reducing symptoms and increasing the peak urinary flow rate. The effect of terazosin on the peak urinary flow rate was apparent in studies as short as 8 weeks. Most importantly, the effect of terazosin on symptoms and peak urinary flow rate was independent of the baseline prostate size for the range of prostate volumes reported.

Apoptotic activity of doxazosin on prostate stroma in vitro is mediated through an autocrine expression of TGF-beta1

BACKGROUND

Doxazosin, an alpha-adrenergic antagonist, has been shown to induce apoptosis in prostatic stromal cells. The mechanism of this apoptotic action by Doxazosin remains undefined. The present study was carried out to demonstrate that the effect of Doxazosin on apoptosis of prostate stromal cells is mediated through an autocrine action of TGF-beta1.

METHODS

Primary cultures of human prostate cells were treated with varying concentrations of Doxazosin (0, 0.1, 1, 10, and 100 microM) for a period up to 3 days. At the end of the 3-day culture, cell numbers were counted. Apoptosis was assessed by a colorimetric terminal deoxyribonucleotide transferase labeling technique. TGF-beta1 was determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared to control cultures, cell numbers were significantly decreased as much as 68.4% in cultures treated with 10 microM of Doxazosin after 3 days incubation, while apoptosis increased by 64.7% in cultures treated with the same concentration of Doxazosin after 24 h. This decrease in cell number was reversed when antibody to TGF-beta1 was added to these cultures. Addition of TGF-beta1 (0, 1.0, and 10 ng/mL) to the cultures also decreased the cell numbers. Quantitation of TGF-beta1 in lysates of cells by ELISA revealed that the cells treated with Doxazosin (10 microM) produced as much as 62.5% more TGF-beta1 than in that of untreated cells.

CONCLUSIONS

These results demonstrate that the apoptotic effect of Doxazosin on human prostatic stromal cells is mediated through an autocrine production of TGF-beta1.

Reduction of human prostate tumor vascularity by the alpha1-adrenoceptor antagonist terazosin

BACKGROUND

We previously demonstrated that the quinazoline-derived a1-adrenoceptor antagonists doxazosin and terazosin suppress prostate cancer growth via apoptosis induction. The aim of this study was to determine the potential effect of a1-adrenoceptor antagonists on tumor vascularity of the human prostate.

METHODS

A total of 34 men with benign prostatic hyperplasia (BPH) who have been on terazosin treatment (for the obstructive symptoms) were pathologically diagnosed with prostate cancer following surgery. These patients were stratified according to the length of treatment periods with terazosin into two groups, 1 week-6 months, and 6-17 months. The control group consisted of prostatectomy specimens from 25 untreated prostate cancer patients undergoing surgery for localized disease. Formalin-fixed, paraffin-embedded prostate specimens were analyzed for apoptosis (TUNEL assay), cell proliferation (Ki-67), microvessel density (MVD) (von Willebrand factor/Factor VIII), vascular endothelial growth factor (VEGF) expression, and prostate specific antigen (PSA) immunoreactivity.

RESULTS

A significant induction of apoptosis was observed among cancerous prostatic epithelial cells in the terazosin-treated, as compared to the untreated prostate cancer specimens, while there was no significant change in the proliferative index of the same tumor cell populations after treatment. Furthermore, terazosin resulted in a significant decrease in prostate tissue MVD compared with the untreated group (P < 0.01), that correlated with the increased apoptotic index of the cancerous areas. Tissue PSA expression in the prostatic tumor foci was also markedly reduced after terazosin treatment, while no significant changes in VEGF expression were detected.

CONCLUSIONS

These findings provide the first evidence that terazosin, a quinazoline-based a1-blocker decreases prostate tumor vascularity. Our study has significant clinical implications in identifying selected alpha1-adrenoceptor antagonists as potential anti-tumor agents with apoptotic and anti-angiogenic effects in the human prostate that can be exploited for the treatment of advanced prostate cancer.

Comparison of prazosin, terazosin and tamsulosin: functional and binding studies in isolated prostatic and vascular human tissues

BACKGROUND

Terazosin and tamsulosin are drugs currently used in the treatment of benign prostatic hypertrophy (BPH). The potency of these two alpha(1) receptor antagonists and that of prazosin to inhibit contractions induced by noradrenaline and the binding of [(3)H]-prazosin in human prostate and four different human arterial and venous vessels (saphenous and umbilical veins, renal and mesenteric arteries) was studied.

METHODS

By bioassay and binding studies, we examined the receptor affinities of different alpha(1) receptor antagonists in different human tissues.

RESULTS

pKb of terazosin, tamsulosin, and prazosin obtained in the prostatic tissues (8.15, 9.64, and 8.59, respectively) were not different from those obtained in the umbilical veins (8.07, 9.56, and 8.30, respectively), in the mesenteric artery (8.27, 10.29, and 9.01, respectively), renal artery (8.35, 10.13, and 8.76, respectively) and saphenous vein (7.8, 10.3, and 9.32, respectively). IC(50) (nM) of prazosin, terazosin, and tamsulosin obtained from binding studies in membrane preparations from prostate tissue were similar to those from umbilical veins, saphenous vein, and renal artery.

CONCLUSIONS

All of the evaluated drugs showed similar selectivity for prostatic vs. vascular tissues. Thus, different clinical profiles of the present drugs should not result from their differential affinity for prostatic versus vascular alpha(1)-adrenoceptors.

Effects of alpha(1)-adrenoceptor (alpha(1)-AR) antagonists on cell proliferation and apoptosis in the prostate: therapeutic implications in prostatic disease

BACKGROUND

Benign prostate hyperplasia (BPH) and prostate cancer established that disruption of the molecular mechanisms that regulate apoptosis and cell proliferation among the stromal and epithelial cell populations, may underlie the neoplastic development that characterizes the aging gland. This work examined the effects of selected alpha(1)-adrenoceptor (alpha(1)-AR) antagonists (blockers) on cellular dynamics to determine whether induction of apoptosis or inhibition of proliferation could contribute to the overall clinical profile.

METHODS

Our efforts were focused on investigating whether alpha(1)-AR antagonists of two different chemical classes affect prostate pathophysiology via mechanisms other than smooth muscle contraction. In in vitro experiments, the two clinically used quinazoline alpha(1)-adrenoceptor antagonists terazosin and doxazosin and the chemically-distinct sulphonamide, tamsulosin, were examined for effects on prostatic tumor growth, by inhibiting cell proliferation and'or inducing apoptosis.

RESULTS

Our findings suggest that alpha(1)-AR antagonists, terazosin and doxazosin, suppress prostatic growth by inducing apoptosis in a dose-dependent manner and without affecting cell proliferation. Tamsulosin exerted no effect on prostate cancer cell growth. The apoptotic effect of terazosin and doxazosin appears to be independent of the alpha(1)-adrenoceptor block.

CONCLUSIONS

Taken together, our findings demonstrate the ability of the quinazoline alpha-blockers, terazosin and doxazosin, but not the sulphonamide, tamsulosin, to suppress prostate growth by inducing apoptosis among the epithelial cells in the benign and malignant prostate. These studies underwrite the durability of the response seen in long-term studies with terazosin, and suggest the potential of this drug in the treatment of prostate carcinoma.

Effects of alpha1-adrenoceptor antagonists on cultured prostatic smooth muscle cells

BACKGROUND

alpha1-adrenoceptor (alpha1-AR) antagonists, used to relieve the lower tract urinary symptoms (LUTS) in benign prostate hyperplasia (BPH) patients, are thought to act in inhibiting the contraction of stromal smooth muscle. An attempt was made using new technology to visualize and quantify the effect of alpha1-AR antagonists in a cell culture model of prostatic smooth muscle cells (SMC).

METHODS

Prostatic smooth muscle cells cultured from human prostate tissue were treated with alpha1-AR agonists and antagonists. The effects on cell growth, cell contraction, differentiation status, and apoptosis were determined by means of an MTT cell viability assay, time-lapse video microscopy, RT-PCR analysis, and FACS analysis of annexin V/propidium iodide-stained cells, respectively.

RESULTS

Prostatic smooth muscle cells derived from prostate tissue expressed SMC-specific markers. They showed spontaneous contractions, and phenylephrine increased the percentage of contracting cells by 3-fold. alpha1-AR antagonists inhibited spontaneous as well as phenylephrine-induced contractions. Long-term treatment with doxazosin induced differentiation tended towards a contractile phenotype, as indicated by an increase of the ratio of smooth muscle heavy chain myosin subtypes SM2/SM1. There was, however, no effect on cell growth. High concentrations of antagonist (100 microM) induced apoptosis in about 80% of the treated SMC. This effect was not cell-type-specific and was also seen in skin fibroblasts and immortalized prostate epithelial cells.

CONCLUSION

In an easy-to-handle cell culture model of prostatic smooth muscle cells, the effects of alpha1-AR antagonists on cell contraction, growth, and differentiation can be investigated. The results indicate that in addition to inhibition of cell contraction, alpha1-AR antagonists have the potential to induce apoptosis.

Future concepts in the medical therapy of benign prostatic hyperplasia

The standard medical therapy for symptomatic benign prostatic hyperplasia is still alpha-blockers and 5alpha-reductase inhibitors. Ongoing studies demonstrate the long-term safety and efficacy of these two classes of therapeutic approaches. Although there have been no new Food and Drug Administration approved medical therapies for the treatment of benign prostatic hyperplasia over the past year, interest in and the use of phytotherapeutic agents continues to increase. In this review, we will discuss the developments that have occurred over the past year in the medical management of benign prostatic hyperplasia. In addition, we present ongoing efforts at our center to obtain a better understanding of and manipulate the apoptotic pathway as it pertains to the pathophysiology of benign prostatic hyperplasia.

Alpha adrenoceptor antagonists in the year 2000: is there anything new?

Selective alpha1-adrenergic blockade is now a well accepted and widely used therapeutic treatment for patients presenting with symptomatic bladder outlet obstruction thought to be associated with benign prostatic hyperplasia. This review summarizes the recent developments in this field relating to the subject of receptor subtype selectivity and the potential relevance of this to clinical usefulness of existing drug therapy. Whilst a number of unanswered questions remain as to the exact mechanisms of both drug action and side-effect profile, nevertheless it is clear that existing clinically available alpha1-antagonists provide a safe, effective and generally well tolerated therapy for patients with lower urinary tract symptoms thought to be associated with benign prostatic obstruction. The implications of the ALLHAT study are discussed.

Combined effect of terazosin and finasteride on apoptosis, cell proliferation, and transforming growth factor-beta expression in benign prostatic hyperplasia

BACKGROUND

Medical treatment of benign prostatic hyperplasia (BPH) targets relief of symptoms by causing either relaxation of the prostatic smooth muscle with alpha1 adrenergic blockade, or shrinkage of the gland with 5alpha-reductase inhibitors. We recently demonstrated that alpha1-blockers, such as terazosin, induce apoptosis in prostatic cells. In this study, we examined the combined effect of finasteride and terazosin on the rate of apoptosis and cellular proliferation to investigate their potential synergy at the cellular level.

METHODS

Prostate specimens were obtained from men who were treated with either finasteride (n = 24), terazosin (n = 42), or combination therapy (n = 10) for varying time periods (1 week to 36 months) for the relief of the symptoms of BPH. The proliferative and apoptotic indices of both stromal and epithelial prostatic cell populations were determined. Antibodies against TGF-beta1 and TbetaRII were used to examine the immunoreactivity of TGF-beta1 and TbetaRII, respectively, in all prostate tissue sections.

RESULTS

The apoptotic index in both prostate cell populations was significantly higher following the combination treatment compared to terazosin or finasteride alone. There were no significant changes in the rate of cellular proliferation with any treatment. Furthermore, there was a significant increase in TGF-beta1 expression in the prostates of patients treated with terazosin or combination therapy, while there was no change in TbetaRII expression.

CONCLUSIONS

These results support the concept that induction of prostate apoptosis is a potential molecular mechanism underlying the combination effect of alpha1 blockade with 5alpha-reductase inhibitors in the effective treatment of BPH. The upregulation of TGF-beta1 implies a role for this ligand as an effector of apoptosis induction in response to alpha1-blockade or finasteride therapy of BPH patients.

Comparison of histological compositions and apoptosis in canine spontaneous benign prostatic hyperplasia treated with androgen suppressive agents chlormadinone acetate and finasteride

PURPOSE

Chlormadinone acetate and finasteride are androgen suppressive agents clinically used for benign prostatic hyperplasia but their mechanism for inducing prostatic atrophy differs. We investigated the effect of these androgen suppressive agents on prostatic histology and apoptosis using the spontaneous canine benign prostatic hyperplasia model.

MATERIALS AND METHODS

Animals were treated with oral chlormadinone acetate or finasteride for 25 weeks. The prostatic volumes were analyzed every 5 weeks. Prostatic androgen and estrogen concentrations, histological composition and apoptosis were determined at the end of treatment. Apoptosis was measured by in situ labeling of 3' hydroxy ends of the DNA breaks using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling method.

RESULTS

There was a similar volume reduction effect with 0.3 mg./kg. chlormadinone acetate daily and 1 mg./kg. finasteride daily. Chlormadinone acetate decreased testosterone and dihydrotestosterone but finasteride decreased only dihydrotestosterone in the prostate gland. The concentration ratio of estradiol-to-total androgen in the prostate was significantly increased in finasteride treated canines. Chlormadinone acetate and finasteride decreased the epithelial and stromal components. The extent of apoptosis observed in the prostate was significantly higher in the chlormadinone acetate group compared to that of the control and finasteride groups.

CONCLUSIONS

Although a similar effect of chlormadinone acetate and finasteride was observed in the induction of prostatic regression and composition of the histological components, the sustained increase in apoptosis was observed only in chlormadinone acetate treated canines. We suggest that different intraprostatic endocrine environments created by chlormadinone acetate or finasteride, which have different intraprostatic testosterone levels and estradiol-to-androgen ratios, may be responsible for the different outcomes in the extent of apoptosis.

Alpha-blockade downregulates myosin heavy chain gene expression in human benign prostatic hyperplasia

OBJECTIVES

Smooth muscle (SM), a major component of prostate stroma, plays an important role in the pathogenesis of benign prostatic hyperplasia. In many muscle systems, steroid hormones and alpha(1)-adrenergic neurotransmitters tightly regulate expression of contractile proteins. In this study, SM content and the expression of myosin heavy chain (MHC) in tissues from patients with benign prostatic hyperplasia treated with androgen ablation or alpha-blockade were compared with untreated controls.

METHODS

Prostatic periurethral tissue specimens from patients receiving luteinizing hormone-releasing hormone analogues (n = 12), alpha-blocking agents (n = 12), and no treatment (n = 13) were examined. The samples were analyzed for SM MHC mRNA expression using competitive reverse transcription-polymerase chain reaction. SM content was measured by morphometric analysis of trichrome-stained sections.

RESULTS

Stromal SM constituted 45.4% +/- 8.6%, 48.1% +/- 18.4%, and 45.9% +/- 10.8% of the total tissue in androgen ablated, alpha-blocked, and untreated tissues, respectively. No significant difference was observed among these three groups (P = 0.84, analysis of variance). However, SM MHC mRNA expression was markedly decreased in the alpha-blockade group (0.15 +/- 0.02 attomole/mg tissue) compared with the androgen-ablated (0.58 +/- 0.15 attomole/mg tissue) or control (0.44 +/- 0.10 attomole/mg tissue) groups. The relationship between SM content and expression of SM MHC significantly differed among the groups (P = 0.02, analysis of variance).

CONCLUSIONS

Androgen ablation and alpha-blockade do not appear to alter the histologic characteristics of prostate stroma in men with symptomatic benign prostatic hyperplasia. However, contractile protein gene expression in stromal SM cells is significantly altered after alpha-blockade. These data suggest that, in addition to the simple relaxation of muscle tone, alpha-blocking agents may affect the phenotypic expression of contractile proteins in prostate SM cells.

Induction of apoptosis and inhibition of cell proliferation by the lipido-sterolic extract of Serenoa repens (LSESr, Permixon in benign prostatic hyperplasia

BACKGROUND

To determine the mechanism by which prostate volume increases during the development of BPH and to evaluate the effect of LSESr (Permixon), a phytotherapeutic agent, we investigated apoptosis and cell proliferation in the stroma and epithelium of normal prostate and of BPH tissues from patients treated with or without LSESr.

METHODS

MIB-1 staining and the in situ end-labeling assay were used to evaluate the proliferative-apoptotic balance in normal prostates and in BPH tissues. Quantitative assessment was performed using an image analysis system.

RESULTS

In normal prostates, there was no significant difference between apoptotic and proliferative indices. Cell numbers and proliferative indices were higher in BPH than in normal prostates, while apoptosis values were similar. In the BPH treated group, LSESr significantly inhibited proliferation and induced cell death in both epithelium and stroma.

CONCLUSIONS

Induction of apoptosis and inhibition of cell proliferation are likely to be the basis for the clinical efficacy of LSESr.

Induction of apoptosis in the prostate by alpha1-adrenoceptor antagonists: a novel effect of "old" drugs

Advances in our understanding of the integrated functions governing prostate cell proliferation and cell death imply that effective therapies for prostate neoplasia should not only be molecularly targeted, but should be customized to take into account the delicate balance of opposing growth influences. Evidence from studies on the dynamics of prostate growth in benign prostatic hyperplasia (BPH) and prostate cancer established that disruption of the molecular mechanisms that regulate apoptosis and cell proliferation among the stroma and epithelial cell populations may underlie the neoplastic development that characterizes the aging gland. Our own efforts have been focused on investigating whether a1-adrenoceptor antagonists clinically used for the relief of the obstructive symptoms associated with BPH affect prostate pathophysiology via mechanisms other than smooth muscle contraction. Such efforts led to the identification of a novel effect of two alpha1-adrenoceptor antagonists, doxazosin and terazosin. More recent in vitro experiments examined the potential anti-tumor action of three clinically used alpha1-adrenoceptor antagonists--doxazosin, terazosin and tamsulosin--against prostate cancer cell growth. These findings demonstrate the ability of doxazosin and terazosin, but not tamsulosin, to suppress prostate growth by inducing apoptosis among the epithelial cells in the benign and malignant prostate. Thus, evidence indicates that rather than just causing pure relaxation of the smooth muscle, certain alpha1-blockers can also affect the dynamics of prostate growth by changing the balance between prostate cell proliferation and apoptosis at the expense of the proliferative process.

Alpha-blockers: an effective treatment for prostatitis?

Chronic prostatitis is a multifaceted problem affecting men that is both poorly understood and poorly treated. It is inevitable, therefore, that no single treatment will benefit all patients. However, data suggest that some patients' problems can be treated effectively with alpha-blockers. The prostate is rich in alpha-adrenergic receptors, and some urodynamic studies have shown a failure of the bladder neck to relax during voiding. Other studies have demonstrated turbulent flow in the prostate leading to prostatic duct reflux. Because urine is acidic, reflux into the prostatic ducts will cause inflammation and pain. Thus alpha-blockers are an effective treatment for men with prostatitis caused by dysfunctional voiding.

Modulating effect of estrogen and testosterone on prostatic stromal cell phenotype differentiation induced by noradrenaline and doxazosin

BACKGROUND

Noradrenaline (NA) has been shown to enhance expression of the contractile phenotype of human prostatic stromal cells in tissue culture. This study examined the possibility that changing levels of sex hormones in elderly men with BPH may modulate the differentiating effect of NA and hence the efficacy of alpha(1)-adrenoceptor-blocking drugs.

METHODS

Confluent, quiescent stromal cell cultures from 6 different patients were treated with combinations of 20 microM NA, 1 microM doxazosin, 0.1 microM beta-estradiol, and 0.1 microM testosterone, over a period of 10 days. Harvested cells were labelled with fluorescein-conjugated antisera to alpha-smooth muscle actin and myosin to identify cells of contractile phenotype which were thereafter analyzed flow-cytometrically.

RESULTS

NA increased mean immunoexpression of both actin and myosin. Enhancement of myosin expression was highly significant (P </= 0.02). This effect was incompletely opposed by doxazosin. Neither estradiol nor testosterone influenced mean expression of contractile filaments and did not significantly enhance or inhibit the effects of NA or doxazosin. However, both sex hormones exhibited a differentially powerful effect on cell lines from individual patients. The expression of myosin increased by NA was further elevated by addition of estradiol in four of the cell lines and by testosterone in three.

CONCLUSIONS

The data suggest that levels of estrogens and androgens, either alone or in combination, are unlikely to predict the development of obstructive symptoms in patients with BPH or their response to doxazosin. Nevertheless, prostatic stromal cells from individual patients may be exceptionally sensitive to both sex hormones, with enhanced modulation towards a contractile phenotype. Since alpha- and beta-subtypes of the estrogen receptor are differentially expressed between the stroma and epithelium of the early fetal prostate, it is likely that interaction between sex hormones and noradrenaline is an important factor in determining the phenotypic composition of prostatic stroma at this early stage of development, and possibly predisposition to BPH during later adult life.

Doxazosin: a new cytotoxic agent for prostate cancer?

OBJECTIVE

To determine the sensitivity of drug-resistant prostate cancer cell lines to doxazosin-mediated cell death, and the effects of combining doxazosin and chemotherapeutic agents on these cell lines. Materials and methods The cytotoxic effect of doxazosin was initially evaluated in the prostate carcinoma cell lines DU145 and PC-3. Doxazosin was combined either with adriamycin, etoposide or paclitaxel after its cytotoxic effects were detected in these cell lines. The tetrazolium dye (MTT) assay and trypan blue dye-exclusion tests were used to determine drug-mediated cytotoxicity. Experiments were performed at least three times and representative data are presented.

RESULTS

Both cell lines were sensitive to doxazosin-mediated cytotoxicity and the maximum cytotoxicity was achieved after 72 h. While cell death increased with increasing concentrations of doxazosin, 60 micromol/L doxazosin killed more than half of the cells in these cell lines. The combination of doxazosin with both adriamycin and etoposide resulted in significant synergistic cytotoxic activity at subtoxic concentrations of the drugs. Interestingly, the combination of doxazosin and paclitaxel resulted in antagonistic activity.

CONCLUSION

Doxazosin-mediated cytotoxicity in the drug-resistant human prostate carcinoma cell lines was confirmed. Combinations of doxazosin with either adriamycin and etoposide, but not paclitaxel, had synergistic cytotoxic activity in these tumour cell lines. These results suggest that doxazosin could be a new cytotoxic agent, either used alone or combined, in the treatment of prostate cancer.

Modulation of the differentiation status of cultured prostatic smooth muscle cells by an alpha1-adrenergic receptor antagonist

BACKGROUND

Prostatic stromal cells are believed to be a key factor in the pathogenesis of benign prostatic hyperplasia (BPH). The effect of phenylephrine, an alpha1-adrenergic receptor agonist, and doxazosin, an alpha1-adrenergic receptor-specific antagonist, on the expression of smooth muscle myosin-heavy-chain isotypes SM-1 and SM-2 was tested in an in vitro model of prostatic smooth muscle cells (SMC).

METHODS

Primary prostatic stromal cells, grown in SMC-specific medium, were treated with 10 microM of phenylephrine or 1 microM of doxazosin or a combination of both. SM-2 to SM-1 mRNA ratios and expression of alpha1-adrenergic receptor subtypes were determined by means of reverse transcriptase polymerase chain reaction (RT-PCR) techniques. Cell growth was measured by a cell viability assay.

RESULTS

SM-1 mRNA and only very low levels of SM-2 mRNA were detected in prostatic SMC cultures grown for 4 days in a serum-free base medium. After 6 days of treatment, SM-2 expression increased, highest in the doxazosin-treated cultures. In comparison to unstimulated cells, a statistically significant 10-fold increase of the SM-2:SM-1 ratio was measured in doxazosin-treated cultures. Analysis of alpha1-adrenergic receptor subtype expression revealed the presence of mRNAs of subtypes 1d and 1b mRNAs. Subtype 1a was not expressed. Phenylephrine and doxazosin showed no significant effect on cell proliferation and on alpha1d-adrenergic receptor expression.

CONCLUSIONS

SMC can differentiate from a proliferative to a contractile phenotype, which is accompanied by increased expression of isotope 2 of smooth muscle myosin heavy chain. Our results suggest that doxazosin seems to have a long-term effect on the differentiation of prostatic stromal cells, indicating that alpha1-adrenergic receptor antagonists do not act solely on SMC contractility.