Tissue content of dihydrotestosterone in human prostatic hyperplasis is not supranormal

Early investigational agents for the treatment of benign prostatic hyperplasia'

INTRODUCTION

Benign prostatic hyperplasia (BPH), as a clinical entity that affects many people, has always been in the forefront of interest among researchers, pharmaceutical companies, and physicians. Patients with BPH exhibit a diverse range of symptoms, while current treatment options can occasionally cause adverse events. All the aforementioned have led to an increased demand for more effective treatment options.

AREAS COVERED

This review summarizes the outcomes of new medications used in a pre-clinical and clinical setting for the management of male lower urinary tract symptoms (LUTS)/BPH and provides information about ongoing trials and future directions in the management of this condition. More specifically, sheds light upon drug categories, such as reductase‑adrenoceptor antagonists, drugs interfering with the nitric oxide (NO)/cyclic guanosine monophosphate (GMP) signaling pathway, onabotulinumtoxinA, vitamin D3 (calcitriol) analogues, selective cannabinoid (CB) receptor agonists, talaporfin sodium, inhibitor of transforming growth factor beta 1 (TGF-β1), drugs targeting the hormonal control of the prostate, phytotherapy, and many more.

EXPERT OPINION

Clinical trials are being conducted on a number of new medications that may emerge as effective therapeutic alternatives in the coming years.

Role of prostate stem cells and treatment strategies in benign prostate hyperplasia

Benign prostate hyperplasia (BPH) is a progressive disease with a direct correlation between incidence and age. Since the treatment and management of BPH involve harmful side effects and decreased quality of life for the patient, the primary focus of research should be to find better and longer-lasting therapeutic options. The mechanisms regulating prostate stem cells in development can be exploited to decrease prostate growth. BPH is defined as the overgrowth of the prostate, and BPH is often diagnosed when lower urinary tract symptoms (LUTS) of urine storage or voiding symptoms cause patients to seek treatment. While multiple factors are involved in the hyperplastic growth of the stromal and epithelial compartments of the prostate, the clonal proliferation of stem cells is considered one of the main reasons for BPH initiation and regrowth of the prostate after therapies for BPH fail. Several theories explain possible reasons for the involvement of stem cells in the development, progression, and pathogenesis of BPH. The aim of the current review is to discuss current literature on the fundamentals of prostate development and the role of stem cells in BPH. This review examines the rationale for the hypothesis that unregulated stem cell properties can lead to BPH and therapeutic targeting of stem cells may reduce treatment-related side effects and prevent the regrowth of the prostate.

Effects of testosterone replacement on serotonin levels in the prostate and plasma in a murine model of hypogonadism

Benign prostate hyperplasia is a dysfunctional disease with an elevated prevalence. Despite the accepted impact of aging and testosterone (TES) in its pathophysiology, its aetiology remains unknown. Recent studies described that serotonin (5-HT) inhibits benign prostate growth through the modulation of the androgen receptor, in the presence of TES. Accordingly, this work aimed to determine the impact of castration and TES replacement in plasmatic and prostatic 5-HT regulation. C57BL/6 mice were submitted to surgical castration and divided into three groups, continually exposed to either vehicle or different TES doses for 14 days. Plasmatic 5-HT concentration was measured before and after castration, and after TES reintroduction. Finally, total prostatic weight and intra-prostatic 5-HT were determined in the different groups. Our results demonstrate that mice prostate exhibits high 5-HT tissue levels and that intra-prostatic total 5-HT was independent of castration or TES reintroduction, in all studied groups. Also, 5-HT plasmatic concentration significantly increased after castration and then normalized after TES administration. Our findings revealed that mice prostate has a high 5-HT content and that total prostatic 5-HT levels do not depend on androgens' action. On the other hand, castration induced a significant increase in plasmatic 5-HT concentration, raising the hypothesis that androgens might be regulating the production of extra-prostatic 5-HT.

Quisqualis indica extract ameliorates low urinary tract symptoms in testosterone propionate-induced benign prostatic hyperplasia rats

Benign prostate hyperplasia (BPH) is a common disease in old-age males, accounting for approximately 77% of morbidity within the age range of 40 to 70 years. It has been shown that morbidity increases with social graying. Quisqualis indica linn (QI) has been used to treat inflammation, stomach pain, and digestion problems. In this study, we evaluated the symptom-regulating effects of QI extract on a testosterone-induced BPH rat model. After inducing BPH in rats using testosterone propionate (TP) injection, we assessed basal intraurethral pressure (IUP) and increments of IUP elicited by electrical field stimulation (5 V, 5, 10, or 20 Hz) or phenylephrine (Phe) (0.01, 0.03, 0.1 mg/kg IV). To induce BPH, 8-week-old rats were subjected to a daily subcutaneous TP (3 mg/kg) injection for 4 weeks. Finasteride (Fina) (10 mg/kg PO) was administered to the rats in the first treatment, while QI (150 mg/kg PO) was administered to those in the second group. Blood pressure was measured together with IUP, after which low urinary tract (LUT), ventral prostate (VP), testicle, and corpus spongiosum were isolated and weighed. Basal IUPs for the Fina- and QI-treated groups were 87.6 and 86.8%, respectively.

LUT and VP organ weights in the QI group were lower than those in the Fina group. However, the QI group showed significantly reduced electrical stimulated or Phe-induced IUP increment compared to the Fina and BPH groups. These results proved that QI can be beneficial for BPH symptoms by inhibiting 5α-reductase and consequently decreasing prostate and releasing urinary pressure.

Diet-Induced Hyperinsulinemia as a Key Factor in the Etiology of Both Benign Prostatic Hyperplasia and Essential Hypertension?

Benign prostatic hyperplasia and hypertension are common age-related comorbidities. Although the etiology of benign prostatic hyperplasia (BPH) is still largely unresolved and poorly understood, a significant age-independent association was found between BPH and hypertension, indicating a common pathophysiological factor for both diseases. It has previously been suggested that the development of essential hypertension may be related to diet-induced hyperinsulinemia. This study follows the question, whether BPH may develop due to the same mechanism, thereby explaining the well-known comorbidity of these 2 disorders. The scientific evidence presented shows that BPH and hypertension share the same pathophysiological changes, with hyperinsulinemia as the driving force. It further shows that significant dietary changes during human history cause disruption of a finely tuned metabolic balance that has evolved over millions of years of evolution: high-insulinemic food, typical of current “Western” diets, has the potential to cause hyperinsulinemia and insulin resistance, as well as an abnormally increased activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system, alterations that play a pivotal role in the pathogenesis of BPH and hypertension.

Circadian genes and risk of prostate cancer in the prostate cancer prevention trial

Circadian genes have been considered as a possible biological mechanism for the observed relationship between circadian rhythm disruptions and increased risk of hormone-related cancers. In the current study, we investigated the relationship between circadian gene variants and prostate cancer risk and whether reducing bioavailable testosterone modifies the circadian genes-prostate cancer relationship. We conducted a nested case-control study among Caucasian men in the Prostate Cancer Prevention Trial (PCPT), a randomized placebo-controlled clinical trial to assess if finasteride (an androgen bioactivation inhibitor) could prevent prostate cancer. We evaluated the associations between 240 circadian gene variations and prostate cancer risk among 1092 biopsy-confirmed prostate cancer cases and 1089 biopsy-negative controls in the study (642 cases and 667 controls from the placebo group; 450 cases and 422 controls from the finasteride group), stratified by treatment group. Among men in the finasteride group, there were suggestive associations between NPAS2 variants and total prostate cancer risk, with one SNP remaining statistically significant after Bonferroni correction (rs746924, odds ratio [OR] = 1.5, P = 9.6 × 10^-5 ). However, we found little evidence of increased prostate cancer risk (overall or by low/high grade) associated with circadian gene variations in men of the placebo group, suggesting potential modification of genetic effects by treatment. We did not find strong evidence that circadian gene variants influenced prostate cancer risk in men who were not on finasteride treatment. There were suggestive associations between NPAS2 variants and prostate cancer risk among men using finasteride, which warrants further investigations.

Testosterone and dihydrotestosterone levels in the transition zone correlate with prostate volume

BACKGROUND

There is still no consensus regarding intraprostatic androgen levels and the accumulation of androgens in the hyperplastic prostatic tissue. The current opinion is that intraprostatic dihydrotestosterone (DHT) concentrations are maintained but not elevated in benign prostatic hyperplasia (BPH), while there is no similar data concerning intraprostatic testosterone (T).

METHODS

Tissue T (tT) and tissue DHT (tDHT) concentration were determined in 93 patients scheduled for initial prostate biopsy. The criteria for biopsy were abnormal DRE and/or PSA > 4 ng/mL. Total prostate volume (TPV) was determined by transrectal ultrasound (TRUS). During TRUS- guided prostate biopsy, 10-12 samples were collected from the peripheral zone (PZ) and two additional samples were collected from the transition zone (TZ). The samples from the TZ were immediately frozen in liquid nitrogen at -70°C, and transported for tissue androgen determination, using liquid chromatography mass spectrometry (LC-MS).

RESULTS

Pathological analysis revealed that prostate cancer (PCa) was present in 45 and absent in 48 patients. In the whole group, there were 42 men with small prostate (TPV < 30 mL) and 51 with enlarged prostate (TPV ≥ 31 mL). The overall average tT level was 0.79 ± 0.66 ng/g, while the average tDHT level was 10.27 ± 7.15 ng/g. There were no differences in tT and tDHT level in prostates with and without PCa. However, tT and tDHT levels were significantly higher in larger, than in smaller prostates (tT: 1.05 ± 0.75 and 0.46 ± 0.29 ng/g, and tDHT: 15.0 ± 6.09 and 4.51 ± 2.75 ng/g, respectively). There were strong correlations between tT and TPV (r = 0.71), and tDHT and TPV (r = 0.74).

CONCLUSIONS

The present study confirmed that both T and DHT accumulated in the stroma of enlarged prostates; the degree of accumulation correlated with prostate volume.

Upregulation of Phosphodiesterase type 5 in the Hyperplastic Prostate

Both erectile dysfunction (ED) and lower urinary tract symptoms (LUTS)/benign prostatic hyperplasia (BPH) are common in the aging male. Numerous clinical trials have demonstrated the efficacy and safety of phosphodiesterase type 5 inhibitors (PDE5-Is) for treating LUTS/BPH with/without ED. However, the influence of BPH on prostatic PDE5 expression has never been studied. A testosterone-induced rat model of BPH was developed and human hyperplastic prostate specimens were harvested during cystoprostatectomy. PDE5, nNOS, eNOS and α₁-adrenoreceptor subtypes (α_1aARs, α_1bARs and α_1dARs) were determined with real-time RT-PCR for rat tissues whilst PDE5 and α₁-adrenoreceptor subtypes were determined in human samples. PDE5 was further analyzed with Western-blot and histological examination. Serum testosterone was measured with ELISA. The rat BPH model was validated as having a significantly enlarged prostate. PDE5 localized mainly in fibromuscular stroma in prostate. Our data showed a significant and previously undocumented upregulation of PDE5 in both rat and human BPH, along with increased expression of nNOS and α_1dARs for rat tissues and α_1aARs for human BPH. The upregulation of PDE5 in the hyperplastic prostate could explain the mechanism and contribute to the high effectiveness of PDE5-Is for treating LUTS/BPH. Fibromuscular stroma could be the main target for PDE5-Is within prostate.

Serum Testosterone, 17β-Estradiol and PSA Levels in Subjects with Prostate Disorders

Prostate carcinoma is the most frequently diagnosed malignancy and the second leading cause of death as a result of cancer in men in the US and other parts of the world. There are conflicting reports on the serum levels of testosterone and 17β-estradiol (E2) in benign prostatic hyperplasia (BPH) and prostate cancer. This study was designed to evaluate the serum concentrations of these hormones in patients with these disorders. Serum levels of prostate specific antigen (PSA), total testosterone and estradiol were determined in 228 subjects comprising of 116 subjects with BPH, 62 subjects with prostate cancer (CaP) and 50 age-matched apparently healthy controls, using ELISA methods. PSA levels were significantly elevated (p < 0.05) in BPH subjects than controls, while there was no significant difference (p > 0.05) in testosterone and estradiol levels of these subjects. PSA and estradiol levels were significantly higher (p < 0.05) in CaP subjects than in controls, while there was no observed significant difference (p > 0.05) in testosterone levels. CaP subjects had significantly raised PSA, testosterone, and estradiol levels than BPH subjects. The mean molar ratio of testosterone: E2 was lowest among CaP patients (134:1) and highest among controls (166:1). Significant positive correlation between PSA and 17β-estradiol was observed in prostate disorders (BPH and CaP patients: r = 0.347; p = 0.000). Significant negative correlations between testosterone and PSA were also observed among BPH patients (r = -0.221, p = 0.049) and control subjects (r = -0.490, p = 0.000). No significant correlation existed between testosterone and PSA in CaP patients (r = 0.051, p = 0.693). Correlations between age and estradiol in both BPH and CaP were not significant (p > 0.05). This study has shown that, there was a significant increase in serum estradiol in CaP subjects, while the testosterone levels in both BPH and CaP subjects were not different from those of controls.

High testosterone levels in prostate tissue obtained by needle biopsy correlate with poor-prognosis factors in prostate cancer patients

Background

There is currently no consensus on the correlations between androgen concentrations in prostate tissue and blood and stage and pathological grade of prostate cancer. In this study, we used a newly-developed ultra-sensitive liquid-chromatography tandem mass spectrometry method to measure testosterone (T) and dihydrotestosterone (DHT) concentrations in blood and needle biopsy prostate specimens from patients with prostate cancer.

Methods

We analyzed androgen levels in 196 men diagnosed with prostate cancer. All patients had undergone systematic needle biopsy, and an additional needle biopsy from the peripheral zone was conducted for the simultaneous determination of T and DHT. We analyzed the relationships between T and DHT levels in tissue and blood and Gleason score, clinical stage, and percentage of positive biopsy cores, using multivariate analysis.

Results

The median T and DHT levels in blood were 3551.0 pg/mL and 330.5 pg/mL, respectively. There was a strong correlation between serum T and DHT. The median T and DHT levels in prostate tissue were 0.5667 pg/mg and 7.0625 pg/mg, respectively. In multivariate analysis, serum prostate-specific antigen and tissue T levels were significantly associated with poor prognosis; high T levels in prostate tissue were significantly related to high Gleason score (p = 0.041), advanced clinical stage (p = 0.002), and a high percentage of positive biopsy cores (p = 0.001).

Conclusions

The results of this study indicate that high T levels in prostate tissue are related to high Gleason score, advanced clinical stage, and a high percentage of positive biopsy cores in patients with prostate cancer. T level in needle biopsy specimens may therefore be a useful prognostic factor in prostate cancer patients.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-717) contains supplementary material, which is available to authorized users.

Fat boosts, while androgen receptor activation counteracts, BPH-associated prostate inflammation

BACKGROUND

Metabolic syndrome (MetS) and benign prostate hyperplasia (BPH) are often comorbid. Chronic inflammation, a determinant pathogenic factor for BPH, is a putative link between the two conditions.

METHODS

In a multi-center cohort of BPH patients (n = 244) who underwent prostatectomy, we evaluated whether MetS is associated with prostatic inflammation in BPH specimens. In addition, we investigated the in vitro inflammatory effects of metabolic insults on human prostatic myofibroblastic cells (hBPH).

RESULTS

Inflammatory infiltrates score (IS) in prostatectomy specimens showed a step-wise association with the number of MetS factors present (P = 0.001). After adjusting for age, reduced HDL cholesterol, and elevated triglycerides were the only factors significantly associated with IS. Increased IS was also significantly associated with hypogonadism. In an age- and testosterone (T)-adjusted model, dyslipidemia was still associated with IS. To investigate whether metabolic factors could directly trigger prostate inflammation, we performed preliminary studies in myofibroblastic hBPH. Among the different factors, oxidized low-density lipoprotein (oxLDL) showed the highest secretion of IL-8 (>10-fold)-a surrogate marker of prostate inflammation--as well as IL-6, and bFGF. Co-treatment with DHT significantly inhibited oxLDL-induced secretion of IL-8, whilst an AR-antagonist, bicalutamide, reversed DHT effects. DHT suppresses oxLDL receptor (LOX-1) expression.

CONCLUSIONS

Our data suggest that fats and insulin could have a detrimental effect on prostate health, boosting inflammation, a key pathogenic factor in BPH. Conversely, beneficial effects of DHT in counteracting lipid- and insulin-induced prostatic alterations, suggest that T-via its conversion into DHT-may have unexpected beneficial effects on prostate health.

Intraprostatic testosterone and dihydrotestosterone. Part I: concentrations and methods of determination in men with benign prostatic hyperplasia and prostate cancer

Owing to inconsistencies and methodological differences, the present peer-reviewed literature lacks conclusive data on the intraprostatic levels of androgens, in particular dihydrotestosterone (DHT), in untreated benign prostatic hyperplasia (BPH) and prostate cancer. To date, no difference has been shown between DHT concentrations in normal prostatic tissue and BPH, and nor has a difference been shown in DHT concentrations between the histologically distinct regions of the prostate. Recent literature has also failed to show a consistent difference in androgen level between BPH and prostate cancer. The role of intraprostatic DHT in the pathogenesis of BPH and in the initiation and progression of prostate cancer thus remains to be established. Increased knowledge of the mechanisms of the androgenic steroid pathways in prostatic diseases, with a special focus on intraprostatic androgen levels may lead to more optimized and more personalized forms of treatment, and probably new therapeutic targets as well.

Androgenetic alopecia as an early marker of benign prostatic hyperplasia

BACKGROUND

Androgenetic alopecia (AGA) and benign prostatic hyperplasia are both androgen-dependent entities that respond to the blocking of 5-alpha-reductase.

OBJECTIVES

The objective of this study was to determine whether prostatic volumes and urinary flow changes were higher in patients with early-onset AGA than in healthy control subjects.

METHODS

This was an observational case-control study of 87 men: 45 with early-onset AGA diagnosed in the dermatology department and 42 control subjects. End-point variables were prostatic volume, measured by transrectal ultrasound, and urinary flow, measured by urinary flowmetry. A hormone study was performed on all participants, and the International Prostate Symptom Score and International Index of Erectile Function score were determined.

RESULTS

The groups did not significantly differ in mean age (cases, 52.7 years vs control subjects, 49.8 years; P = .12). Patients with AGA had significantly higher mean prostate volume (29.65 vs 20.24 mL, P < .0001), International Prostate Symptom Score (4.93 vs 1.23, P < .0001), and prostate-specific antigen value (1.53 vs 0.94 ng/mL, P < .0001) and significantly lower maximum urinary flow (14.5 vs 22.45 mL/s, P < .0001) versus control subjects. Binary logistic regression analysis showed a strong association between the presence of AGA and benign prostatic hyperplasia after adjusting for age, urinary volume, urination time, International Prostate Symptom Score, abdominal obesity, glucose levels, systolic blood pressure, insulin levels, fibrinogen, and C-reactive protein (odds ratio = 5.14, 95% confidence interval 1.23-47.36, P = .041).

LIMITATIONS

The study of larger sample sizes would facilitate stratified analyses according to the Ebling type of androgenetic alopecia.

CONCLUSION

There is a relationship between the presence of AGA and prostate growth-associated urinary symptoms, likely attributable to their pathophysiological similarity. This study suggests that early-onset AGA may be an early marker of urinary/prostatic symptomatology. Future studies may clarify whether treatment of patients with AGA may benefit the concomitant benign prostatic hypertrophy, which would be present at an earlier stage in its natural evolution.

PPARγ: a molecular link between systemic metabolic disease and benign prostate hyperplasia

The emergent epidemic of metabolic syndrome and its complex list of sequelae mandate a more thorough understanding of benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS) in the context of systemic metabolic disease. Here we discuss the nature and origins of BPH, examine its role as a component of LUTS and review retrospective clinical studies that have drawn associations between BPH/LUTS and type II diabetes, inflammation and dyslipidemia. PPARγ signaling, which sits at the nexus of systemic metabolic disease and BPH/LUTS through its regulation of inflammation and insulin resistance, is proposed as a candidate for molecular manipulation in regard to BPH/LUTS. Finally, we introduce new cell and animal models that are being used to study the consequences of obesity, diabetes and inflammation on benign prostatic growth.

Androgens and estrogens in benign prostatic hyperplasia: past, present and future

Benign prostatic hyperplasia (BPH) and associated lower urinary tract symptoms (LUTS) are common clinical problems in urology. While the precise molecular etiology remains unclear, sex steroids have been implicated in the development and maintenance of BPH. Sufficient data exists linking androgens and androgen receptor pathways to BPH and use of androgen reducing compounds, such as 5α-reductase inhibitors which block the conversion of testosterone into dihydrotestosterone, are a component of the standard of care for men with LUTS attributed to an enlarged prostate. However, BPH is a multifactorial disease and not all men respond well to currently available treatments, suggesting factors other than androgens are involved. Testosterone, the primary circulating androgen in men, can also be metabolized via CYP19/aromatase into the potent estrogen, estradiol-17β. The prostate is an estrogen target tissue and estrogens directly and indirectly affect growth and differentiation of prostate. The precise role of endogenous and exogenous estrogens in directly affecting prostate growth and differentiation in the context of BPH is an understudied area. Estrogens and selective estrogen receptor modulators (SERMs) have been shown to promote or inhibit prostate proliferation signifying potential roles in BPH. Recent research has demonstrated that estrogen receptor signaling pathways may be important in the development and maintenance of BPH and LUTS; however, new models are needed to genetically dissect estrogen regulated molecular mechanisms involved in BPH. More work is needed to identify estrogens and associated signaling pathways in BPH in order to target BPH with dietary and therapeutic SERMs.

Estrogen and androgen signaling in the pathogenesis of BPH

Estrogens and androgens have both been implicated as causes of benign prostatic hyperplasia (BPH). Although epidemiological data on an association between serum androgen concentrations and BPH are inconsistent, it is generally accepted that androgens play a permissive role in BPH pathogenesis. In clinical practice, inhibitors of 5α-reductase (which converts testosterone to the more potent androgen dihydrotestosterone) have proven effective in the management of BPH, confirming an essential role for androgens in BPH pathophysiology. To date, multiple lines of evidence support a role for estrogens in BPH pathogenesis. Studies of the two estrogen receptor (ER) subtypes have shed light on their differential functions in the human prostate; ERα and ERβ have proliferative and antiproliferative effects on prostate cells, respectively. Effects of estrogens on the prostate are associated with multiple mechanisms including apoptosis, aromatase expression and paracrine regulation via prostaglandin E2. Selective estrogen receptor modulators or other agents that can influence intraprostatic estrogen levels might conceivably be potential therapeutic targets for the treatment of BPH.

Self-organizing molecular field analysis on pregnane derivatives as human steroidal 5alpha-reductase inhibitors

Normal growth and development of human prostate is regulated by the androgens which balances cell proliferation and apoptosis. Testosterone (T) and dihydrotestosterone (DHT) are the two key androgens that stimulate most of the androgen action in prostate. Testosterone is converted to DHT by the membrane bound NADPH-dependent 5alpha-reductase enzyme. As a consequence of the important observation that progesterone and deoxycortisone inhibits the synthesis of DHT by competing with 4-en-3-one function of the testosterone for the 5alpha-reductase enzyme a number of pregnane derivatives were synthesized and have been reported as inhibitors of human 5alpha-reductase enzyme. Due to lack of information on the crystal structure of human 5alpha-reductase, ligand-based 3D-QSAR study has been performed on pregnane derivatives using self-organizing molecular field analysis (SOMFA) for rationalizing the molecular properties and human 5alpha-reductase inhibitory activities. The statistical results having good cross-validated r(cv)(2) (0.881), non-cross-validated r(2) (0.893) and F-test value (175.527), showed satisfied predictive ability r(pred)(2) (0.777). Analysis of SOMFA models through electrostatic and shape grids provide useful information for the design and optimization of steroidal structure as novel human 5alpha-reductase inhibitors.

Pathology of benign prostatic hyperplasia

The epidemiology of benign prostatic hyperplasia (BPH) is complex and not fully understood. The androgenic hormones testosterones and dihydrotestosterone play at least a permissive and important role. Growth factors and other hormones including estrogens may also play a role. BPH is a truely hyperplastic process resulting in growth of glandular-epithelial and stromal/muscle tissue in the prostate, leading to often measurable growth taking on different shapes and configurations which may impact symptoms and secondary outcomes. It is important to recognize that BPH is a histological conditions, which is one but not the only cause of lower urinary tract symptoms, and may or may not be associated with prostate enlargement and bladder outlet obstruction. Recognizing the different entities and determining their presence in individual patients may help with therapeutic decision making.

A role for epithelial-mesenchymal transition in the etiology of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is usually described as a pathological proliferation of prostatic fibroblasts/myofibroblasts and epithelial cells. In the present study of BPH samples, we have made a morphological and immunohistochemical study of BPH prostatic sections using markers of proliferation, apoptosis, hormone receptors, and TGF-beta signaling. We found no evidence of proliferation in the stroma but in the epithelium of some ducts; 0.7% of the basal and 0.4% of luminal cells were positive for Ki67 and PCNA. Androgen receptor and estrogen receptor beta (ERbeta)1 and ERbetacx were abundant in both stromal and epithelial compartments but cells expressing ERalpha were very rare. What was very common in all BPH samples was the following: (i) regions of the ductal epithelium where the epithelial cells did not express E-cadherin, had lost their polarization, and become spindle shaped (the nuclei of these cells were strongly positive for pSmad 3 and Snail); and (ii) regions where the walls of the blood vessels were extremely thick and there was loss of endothelial layer. Loss of E-cadherin, increased pSmad 3, and high expression of Snail are all characteristic of epithelial-mesenchymal transition (EMT). We conclude that BPH is not a disease of prostatic stromal proliferation but rather of accumulation of mesenchymal-like cells derived from the prostatic epithelium and the endothelium. TGF-beta is thought to play a key role in EMT. Our data suggests that TGF-beta/Smad should be considered as targets for treatment of BPH.

Maintenance of intratumoral androgens in metastatic prostate cancer: a mechanism for castration-resistant tumor growth

Therapy for advanced prostate cancer centers on suppressing systemic androgens and blocking activation of the androgen receptor (AR). Despite anorchid serum androgen levels, nearly all patients develop castration-resistant disease. We hypothesized that ongoing steroidogenesis within prostate tumors and the maintenance of intratumoral androgens may contribute to castration-resistant growth. Using mass spectrometry and quantitative reverse transcription-PCR, we evaluated androgen levels and transcripts encoding steroidogenic enzymes in benign prostate tissue, untreated primary prostate cancer, metastases from patients with castration-resistant prostate cancer, and xenografts derived from castration-resistant metastases. Testosterone levels within metastases from anorchid men [0.74 ng/g; 95% confidence interval (95% CI), 0.59-0.89] were significantly higher than levels within primary prostate cancers from untreated eugonadal men (0.23 ng/g; 95% CI, 0.03-0.44; P < 0.0001). Compared with primary prostate tumors, castration-resistant metastases displayed alterations in genes encoding steroidogenic enzymes, including up-regulated expression of FASN, CYP17A1, HSD3B1, HSD17B3, CYP19A1, and UGT2B17 and down-regulated expression of SRD5A2 (P < 0.001 for all). Prostate cancer xenografts derived from castration-resistant tumors maintained similar intratumoral androgen levels when passaged in castrate compared with eugonadal animals. Metastatic prostate cancers from anorchid men express transcripts encoding androgen-synthesizing enzymes and maintain intratumoral androgens at concentrations capable of activating AR target genes and maintaining tumor cell survival. We conclude that intracrine steroidogenesis may permit tumors to circumvent low levels of circulating androgens. Maximal therapeutic efficacy in the treatment of castration-resistant prostate cancer will require novel agents capable of inhibiting intracrine steroidogenic pathways within the prostate tumor microenvironment.

Prostate tissue androgens: history and current clinical relevance

Direct determination of androgen levels in prostate tissue provides a perspective on the organ that is not available via androgen serum levels. The principle prostatic androgens, primarily dihydrotestosterone (DHT) and secondarily testosterone, can be readily assayed in quick-frozen prostate biopsy cores or surgical specimens. Such assays have proved important in establishing (1) that DHT is a permissive factor in BPH pathogenesis, (2) a mechanism for the treatment of BPH, (3) an understanding of prostate cancer chemoprevention, (4) an explanation for the 'escape' of prostate cancer from castration therapy, (5) prostate safety of testosterone replacement therapy, and (6) insights into the cause of racial differences of prostate cancer. Future opportunities include clarification of new drug mechanisms for BPH and prostate cancer, as well as a better understanding of the pathogenesis of both, and as an aid in individual patient management. Determination of prostate tissue androgens may soon transition from research tool to clinical test.

Persistent intraprostatic androgen concentrations after medical castration in healthy men

CONTEXT

The impact of serum androgen manipulation on prostate tissue hormone levels in normal men is unknown. Studies of men with prostate cancer have suggested that prostatic androgens are preserved in the setting of castration. Tissue androgens might stimulate prostate growth, producing adverse clinical consequences.

OBJECTIVE

The objective of the study was to determine the effect of serum androgen manipulation on intraprostatic androgens in normal men.

DESIGN

Thirteen male volunteers ages 35-55 yr (prostate-specific antigen < 2.0 ng/ml; normal transrectal ultrasound) were randomly assigned to: 1) a long-acting GnRH-antagonist, acyline, every 2 wk; 2) acyline plus testosterone (T) gel (10 mg/d); or 3) placebo for 28 d. Serum hormones were assessed weekly. Prostate biopsies were obtained on d 28. Extracted androgens were measured by RIA, and immunohistochemistry for androgen-regulated proteins was performed.

RESULTS

The mean decrease in serum T was 94%, whereas prostatic T and dihydrotestosterone levels were 70 and 80% lower, respectively, in subjects receiving acyline alone compared with controls (P < 0.05). Despite this decrease in prostate androgens, there were no detectable differences in prostate epithelial proliferation, apoptosis, prostate-specific antigen, and androgen receptor expression.

CONCLUSION

In this small study of healthy subjects, despite a 94% decrease in serum T with medical castration, intraprostatic T and dihydrotestosterone levels remained 20-30% of control values, and prostate cell proliferation, apoptosis, and androgen-regulated protein expression were unaffected. Our data highlight the importance of assessing tissue hormone levels. The source of persistent prostate androgens associated with medical castration and their potential role in supporting prostate metabolism deserves further study.

Seasonal Changes in Mesotocin and Localization of Its Receptor in the Prostate of the Brushtail Possum (Trichosurus vulpecula)

The prostate gland in the brushtail possum grows and regresses seasonally. It has similarities to the human prostate and may therefore provide a unique model for investigating prostatic hyperplasia. Oxytocin has been implicated in the regulation of prostate growth in eutherian mammals, and the initial aim of this study was to identify and localize the marsupial equivalent, mesotocin, and its receptor in the prostate of the brushtail possum. Seasonal changes in prostatic mesotocin concentrations and receptor localization were then assessed and related to prostate growth. Mesotocin and mesotocin receptor gene transcripts with high sequence homology to eutherian oxytocin/oxytocin receptors were demonstrated, and mesotocin, neurophysin, and the receptor were all localized predominantly in the epithelial cells of the glandular acini. Western blot analysis confirmed the presence of a single immunoreactive receptor protein of approximately 60 Mr-3. Prostatic mesotocin concentrations were highest immediately before the increases in prostate weight associated with the autumn and spring breeding periods. At this time, mesotocin receptors were also present in the prostatic capsule in addition to those present in the glandular tissue. Mesotocin concentrations proceeded to decrease in association with the regression of prostate size toward the end of the breeding periods. No significant differences were present in serum testosterone or dihydrotestosterone throughout the year. The identification of mesotocin and its receptor in the possum prostate and the demonstration of seasonal changes in local mesotocin concentrations preceding changes in prostate size suggests that mesotocin may play a physiological role in regulating prostate growth and regression.

Messenger RNA levels and enzyme activities of 5 alpha-reductase types 1 and 2 in human benign prostatic hyperplasia (BPH) tissue

BACKGROUND

Benign prostatic hyperplasia (BPH) development requires testicular androgens and aging. The principle prostatic androgen is dihydrotestosterone (DHT). Testosterone is converted to DHT by the enzyme 5 alpha-reductase. Two distinct 5 alpha-reductase enzymes, types 1 and 2, have been identified. While some studies have suggested that type 2 isoenzyme predominates in the prostate, studies on the prostatic localization of the two isoenzymes are controversial. The purpose of this study was to determine the quantitative expressions of 5 alpha-reductase types 1 and 2 in BPH tissues.

METHODS

We examined the localizations of types 1 and 2 isoenzymes in BPH tissues using immunohistochemical staining and a real-time quantitative RT-PCR assay using the TaqMan system. We measured the enzyme activities of types 1 and 2 at pH values of 7.5 and 5.0, respectively.

RESULTS

Our immunohistochemical study showed that type 1 isoenzyme was expressed predominantly in epithelial cells, whereas type 2 isoenzyme was expressed in both stromal and epithelial cells. The real-time RT-PCR assay demonstrated that the copy numbers of type 1 isoenzyme mRNA were significantly higher than those of type 2 isoenzyme mRNA. There were significant associations between enzyme activity at pH 7.5 and type 1 isoenzyme mRNA expression, and between the activity at pH 5.0 and type 2 mRNA expressions.

CONCLUSIONS

We demonstrated that 5 alpha-reductase type 1 had a specific enzyme activity in the prostate, which supports the hypothesis that the type 1 isoenzyme may play a significant role in maintaining prostate enlargement along with the type 2 isoenzyme.

Pathophysiology, epidemiology, and natural history of benign prostatic hyperplasia

The pathophysiology, epidemiology, and natural history of benign prostatic hyperplasia (BPH) are incompletely understood; however, the development of reliable instruments to measure symptom severity, prostatic enlargement, and bladder outlet obstruction has allowed major advances in their elucidation. The development of lower urinary tract symptoms (LUTS) in the aging male is influenced to some degree by the severity of bladder outlet obstruction and prostatic enlargement. Although the development of LUTS, bladder outlet obstruction, and BPH are age-dependent, they are not necessarily causally related; there are many other factors involved in the pathophysiology of LUTS. The clinically important parameters of disease progression in men with moderate to severe LUTS and low peak flow rates are symptom progression and the development of acute urinary retention (AUR). The risk of AUR is related to both baseline serum prostate-specific antigen level and prostate volume. In men with moderate prostate enlargement, the risk of AUR appears to be high enough to justify intervention with a 5alpha-reductase inhibitor in order to reduce this risk.

Challenges with luteinizing hormone-releasing hormone agonists: flare and surge

Although the mechanism behind the role of circulating androgens in the development and progression of prostatic carcinoma is not totally clear, androgen deprivation therapy remains a mainstay of treatment for this cancer. As surgical orchiectomy has fallen out of favor and the use of estrogens has been associated with cardiac toxicity, pharmacologic approaches have become even more common, namely, the use of luteinizing hormone-releasing hormone (LHRH) agonists. These agents, however, are not without side effects; the primary ones are the "flare" phenomenon, which stems from an initial surge in testosterone level and can include increased pain at metastatic sites, spinal cord compression, and even sudden death. Some studies have reported increased morbidity with the use of LHRH agonists, and while the significance of flare is not entirely known at this point, data seem to indicate that, at least in men with advanced disease, avoiding flare may be prudent.

Androgen supplementation and prostate cancer risk: strategies for pretherapy assessment and monitoring

Since in men androgen levels decrease with age and result in symptoms of hypogonadism, the use of testosterone supplementation to treat symptoms resulting from hypogonadism is increasing. One potential complication of this treatment is the possibility of an increased risk of prostate cancer. Although most authorities agree that androgen is involved in the exacerbation of existing carcinoma of the prostate, the action of androgens on the carcinogenic process is not well understood. Attempts to demonstrate a correlation between hormone levels and prostate cancer have yielded inconsistent results. No clear evidence exists that androgen supplementation to restore physiologic levels produces any deleterious effects on the prostate. It is highly doubtful that when testosterone therapy is administered to middle-aged or older men, any potential prostate cancer promotion effect will be clinically manifested in the absence of already established cancer. It is, however, imperative that existing or developing prostate cancer be ruled out before initiation and during androgen replacement therapy. As with any therapeutic regimen, careful monitoring of the patient receiving treatment is recommended and constitutes good medical care.

Synthesis and evaluation of 2'-substituted 4-(4'-carboxy- or 4'-carboxymethylbenzylidene)-N-acylpiperidines: highly potent and in vivo active steroid 5alpha-reductase type 2 inhibitors

Sixteen compounds derived from N-acyl-4-benzylidenepiperidine-4'-carboxylic acids were synthesized and evaluated for inhibition of rat and human steroid 5alpha-reductase isozymes types 1 and 2. In the dicyclohexylacetyl series, fluorination in the 2-position of the benzene nucleus (15), exchange of the carboxy group by a carboxymethyl moiety (20), and combination of both structural modifications (25) led to highly active inhibitors of the human type 2 isozyme (IC(50) values: 15, 11 nM; 20, 6 nM; 25, 7 nM; finasteride, 5 nM). In vivo all compounds tested markedly reduced the prostate weights in castrated testosterone-treated rats. Oral activity was shown for compound 7. From the finding that compound 15 is active in the rat, although it is a rather poor inhibitor of the rat enzyme and is a strong inhibitor of the human enzyme, it is concluded that it should be highly potent in men.

5-Phenyl substituted 1-methyl-2-pyridones and 4'-substituted biphenyl-4-carboxylic acids. synthesis and evaluation as inhibitors of steroid-5alpha-reductase type 1 and 2

The synthesis of a series of 5-phenyl substituted 1-methyl-2-pyridones (I) and 4'-substituted biphenyl-4-carboxylic acids (II) as novel A-C ring steroidomimetic inhibitors of 5alpha-reductase (5alphaR) is described. Compounds 1-4 (I) were synthesized by palladium catalyzed cross coupling (Ishikura) reaction between diethyl(3-pyridyl)borane and aryl halides (1b-4b) followed by alpha-oxidation with sodium ferrocyanate of the 1-methyl-pyridinium salt. Inhibitors II (5-18) were obtained either by two successive Friedel-Crafts acylations from biphenyl (5a-10a) followed by saponification to yield the corresponding carboxylic acids (5-10) or by Suzuki cross coupling reaction to give the 4'-substituted biphenyl-4-carbaldehydes 11a-18a. The latter compounds were subjected to a Lindgren oxidation to yield compounds 11-18. The compounds were tested for inhibitory activity toward human and rat 5alphaR1 and 2. The test compounds inhibited 5alphaR, showing a broad range of inhibitory potencies. The best compound in series I was the N-(dicyclohexyl)-4-(1,2-dihydro-1-methyl-2-oxopyrid-5-yl)benzamide 4 exhibiting an IC(50) value for the human type 2 enzyme of 10 microM. In series II, the most active compound toward human type 2 isozyme was the 4'-(dicyclohexyl)acetyl-4-biphenyl carboxylic acid (10; IC(50)=220nM). Both series showed only marginal activity toward the human type 1 isozyme. In conclusion, the biphenyl carboxylic acids (II) are more appropriate for 5alphaR inhibition than the 5-phenyl-1-methyl-2-pyridones (I). Especially the 4'-carbonyl compounds 5-10 represent new lead structures for the development of novel human type 2 inhibitors.

5alpha-reductase inhibitors: what role should they play?

The development of finasteride (PROSCAR, Merck & Co., Whitehouse Station, NJ) for the treatment of benign prostatic hyperplasia (BPH) has had variable results. Numerous short-term and long-term studies comparing finasteride with placebo have been reported. The results suggest that, physiologically, treatment with finasteride significantly decreases levels of both serum and intraprostatic dihydrotestosterone about 70% to 80% from baseline. In addition, total gland size decreases significantly-about 15% to 25% from baseline-particularly in the area of the periurethral zone of the prostate after finasteride treatment. Baseline prostate size has been found to have a relation to efficacy of finasteride treatment. The larger the prostate at baseline, the greater the urinary flow rate increase and symptom score decrease compared with placebo. Health-related quality-of-life parameters improved in those taking finasteride. In studies evaluating combination therapy, no significant differences were noted between those treated with an alpha blocker, such as terazosin or doxazosin in combination with finasteride, and those receiving an alpha blocker alone. Long-term finasteride versus placebo studies, such as the PROSCAR Long-Term Efficacy and Safety Study (PLESS), suggest that long-term medical therapy with finasteride affects the natural history of the disease as manifested by the decrease in rates of acute urinary retention and surgery. In patients who are "therapeutic responders," the degree of symptomatic improvement in those treated with finasteride appears to be equal to that seen in patients receiving alpha blockers. Prostate cancer detection rates did not differ between those treated with finasteride and those receiving a placebo. The results of these studies suggest that physicians must evaluate what role finasteride plays in the spectrum of available options for the treatment of BPH and lower urinary tract symptoms. Baseline parameters, such as prostate volume, prostate-specific antigen values, and whether to administer finasteride in combination with alpha blockers, are among the factors that will determine the appropriateness of such therapy.

Role of estrogens in human benign prostatic hyperplasia

The aging process is associated with a progressive decline of plasma testosterone levels, while estrone and estradiol remain unchanged and sex hormone binding globulin (SHBG) increases, with reduction of bioavailable testosterone in prostatic tissue with benign prostatic hyperplasia (BPH) the most important androgen is dihydrotestosterone: with its receptors it is almost uniformly distributed in the epithelial and stromal compartment and is not supranormal. Intraprostatic estrogens and their receptors are elevated and concentrated in the stroma. Androgens may act on the prostate indirectly through the production of growth factors; in human BPH no clear evidence exists on the modulatory effect of estrogens on bFGF, KGF and TGFbeta formation. A western diet, characterized by high fat consumption, predisposes men to BPH, while a diet rich in flavonoids and lignanes, containing phyto-estrogens, lowers this risk. These data suggest that in the medical treatment of BPH, antiestrogens or aromatase inhibitors may be used: however, up to now the clinical results of this treatment are not promising and the improvement of the obstructive symptoms does not exceed that of placebo. A possible explanation of this unsatisfactory result could be that the estrogen reduction secondary to the use of aromatase inhibitors is counterbalanced by the rise of androgen precursors.

Changes in the endocrine environment of the human prostate transition zone with aging: simultaneous quantitative analysis of prostatic sex steroids and comparison with human prostatic histological composition

BACKGROUND

It is well-known that the incidence of benign prostatic hyperplasia (BPH) increases with aging. The age-dependent changes in the ratio of serum sex steroid concentrations may play a role in BPH development. To clarify the relationship between the prostatic tissue concentrations of these steroids and age, we established a precise method of simultaneous quantitative analysis for prostatic sex steroids and used this method to investigate the tissue concentrations of three major sex steroids (testosterone, dihydrotestosterone, and estradiol) in the human prostate.

METHODS

The methodology for the simultaneous quantitative analysis of prostatic sex steroids was established using castrated rat prostatic tissue, coupled with internal standards, for androgen-deprived medium, and the validation of the method was examined. Human prostatic tissues were collected during surgery and immediately frozen at -70 degrees C. Using our method, the steroidal fractions were extracted, purified, and quantified. The proportions of stroma, epithelium, and glandular lumen were measured on each histological specimen, using an image analyzer.

RESULTS

The validation tests showed that our method of quantitative analysis was precise and sensitive enough for the quantification of testosterone, dihydrotestosterone, and estradiol in the prostate. In humans, the prostatic dihydrotestosterone concentration decreased with age, but the concentrations of testosterone and estradiol showed no relation with age. Therefore, the ratio of estradiol to dihydrotestosterone concentration (E2/DHT) in prostate increased with age. The E2/DHT ratio showed a significant positive correlation with the proportion of stroma.

CONCLUSIONS

The age-dependent decrease in prostatic dihydrotestosterone and constant estradiol concentration lead to a relatively estrogen-dominant environment compared to that at younger ages. We assume that this relatively estrogen-dominant status induces stromal proliferation by some mechanism and leads to the development of BPH.

Effect of postnecrotic and alcoholic hepatic cirrhosis on development of benign prostatic hyperplasia

BACKGROUND

The object of this study was to investigate the effects of hepatic cirrhosis on the development of benign prostatic hyperplasia and consequent effects on prostatic volume, serum prostate-specific antigen (PSA), and prostatism symptoms.

METHODS

Sixty patients with postnecrotic cirrhosis and alcoholic cirrhosis at age 40 and over, and 20 voluntary subjects in the same age group with normal hepatic functions, were evaluated with prostatic volume calculation by transrectal ultrasound, symptom scoring according to American Urology Association (AUA) criteria, measurement of serum prostate-specific antigen (PSA), serum total testosterone (TT), free testosterone (FT), estradiol (E2), and calculation of E2/FT ratios, and the results were analyzed statistically by the Mann-Whitney U-test.

RESULTS

Serum FT and TT levels were significantly lower in the hepatic cirrhosis group compared to the control group (P = 0.0000 and P = 0000, respectively). Though mean serum E2 level was a little higher in cirrhotic patients compared to controls, the difference was not significant; however, the higher E2/FT ratio in the cirrhotic group was statistically significant (P = 0.27 and P = 0.0002, respectively). In the cirrhotic group, the decrease in FT and TT levels was greater, as the disease advanced. While E2 and E2/FT ratio increase, correlate with poor prognosis, no statistically significant differences were found. Mean prostatic volume, serum PSA level, and total symptom score were significantly higher in the control group, compared to the cirrhotic group (P = 0.0001, P = 0.0006, and P = 0.002, respectively). Prostatic volume decreased parallel to severity of disease in cirrhotic patients.

CONCLUSIONS

The main reason for the decrease in mean prostatic volume in cirrhotic patients compared to subjects in the same age group with normal hepatic functions was the decrease in serum FT and TT levels, and the secondary cause was the increase in E2/FT ratio, indicating estrogenic predominance.

Association of benign prostatic hyperplasia with male pattern baldness

OBJECTIVES

Both benign prostatic hyperplasia (BPH) and male pattern baldness (androgenic alopecia) share the pathogenesis of an androgen-dependent disorder and afflict a large population of elderly men with chronobiologic progress. However, it is unclear whether these diseases are related epidemiologically. We evaluated the association of frequency and severity of male pattern baldness between patients with BPH and a control group.

METHODS

A total of 225 patients with BPH (mean age 69.3 +/- 6.5 years) and 1 60 controls (mean age 68.5 +/- 6.4 years), all over 60 years of age, were included in this study. The estimation of baldness severity was based on Norwood's classification (grade I to VII). The International Prostate Symptom Score (IPSS) and genetic tendency for baldness were also evaluated. The difference between IPSS and grade of baldness between the two groups was analyzed by the Mann-Whitney test and the frequency of inherited baldness was compared by the chi-square test. Correlation between severity of baldness and IPSS in each group was estimated by Spearman's rank correlation method.

RESULTS

The patients with BPH had an apparently higher grade of male pattern baldness in comparison with that of controls (median value of grade IV versus III, P <0.001). The proportion of men with male pattern baldness of grade IV or higher in the BPH group was significantly larger than that of controls (53.8% versus 36.9%, P <0.01). There was a greater frequency of inherited baldness in the BPH group than in the controls (31.6% versus 12.5%, P <0.001). No significant correlation was noted between baldness severity and IPSS in either group.

CONCLUSIONS

This study demonstrates a strong association of BPH with male pattern baldness.

Serenoa repens (Permixon). A review of its pharmacology and therapeutic efficacy in benign prostatic hyperplasia

Serenoa repens (Permixon) has been available for several years for the treatment of men with benign prostatic hyperplasia (BPH). The drug is the n-hexane lipidosterolic extract of the dwarf American palm (also known as Serenoa repens) and is a complex mixture of various compounds. A number of pharmacodynamic effects have been demonstrated with the lipidosterolic extract of Serenoa repens (LSESR), suggesting multiple mechanisms of action including in vitro inhibition of both type 1 and type 2 isoenzymes of 5 alpha-reductase and interference with binding of dihydrotestosterone to cytosolic androgen receptors in prostate cells. In controlled clinical trials in men with BPH, oral administration of Serenoa repens 160 mg twice daily for 1 to 3 months was generally superior to placebo in improving subjective symptoms, such as dysuria, as well as objective parameters. The frequency of nocturia was reduced by 33 to 74%, while urinary frequency during the day decreased by 11 to 43% and peak urinary flow rate increased by 26 to 50% with Serenoa repens. Corresponding values for placebo were 13 to 39%, 1 to 29% and 2 to 35%. The only large comparative trial conducted to date, in which > 1000 men with moderate BPH were randomised to receive Serenoa repens 160 mg twice daily or finasteride 5 mg once daily for 6 months, demonstrated similar efficacy between the two drugs. No statistically significant difference was demonstrated between treatment groups for improvement in patient self-rated quality-of-life scores and the primary end-point of objective symptom score; International Prostate Symptom Score improved by 37% with Serenoa repens compared with 39% with finasteride. In much smaller comparative trials, few significant differences were demonstrated between Serenoa repens and alpha 1-receptor antagonists, and larger randomised trials of adequate duration are required to better compare the clinical efficacy of these drugs. The most frequently reported adverse events in clinical trials with Serenoa repens have been minor gastrointestinal problems (e.g. nausea and abdominal pain). In conclusion, Serenoa repens is well tolerated and has greater efficacy than placebo and similar efficacy to finasteride in improving symptoms in men with BPH. Although there is a need for further comparative studies, particularly with alpha 2-receptor antagonists, available data indicate that Serenoa repens is a useful alternative to alpha 1-receptor antagonists and finasteride in the treatment of men with BPH.

Prostate volume predicts outcome of treatment of benign prostatic hyperplasia with finasteride: meta-analysis of randomized clinical trials

OBJECTIVES

Six randomized clinical trials have compared at least 1 year of 5 mg finasteride to placebo in the treatment of clinical benign prostatic hyperplasia (BPH). The findings for the 2601 men in these trials provide an opportunity to investigate the heterogeneity of the effects seen in the individual studies and to identify pretreatment predictors of outcomes as expressed by symptoms or peak urinary flow rates.

METHODS

A formal meta-analysis using an Empirical Bayes approach employed data from all finasteride studies which included the Phase III trials in North America and Internationally, the Prospect, Early Intervention, and SCARP trials, and the Veterans Administration Cooperative Study which compared terazosin, finasteride, and the combination of these two drugs. A pooled analysis was also undertaken on the combined dataset.

RESULTS

The effect of finasteride treatment on improvements in total symptom severity, frequency score, and peak urinary flow rate was consistent across all six trials and similar among men with similar prostate volumes at baseline. Symptom severity improved by 1.8 points (95% confidence interval [CI], 0.7 to 2.9) in men with prostate volumes less than 20 cc (n = 72), while the improvement was 2.8 points (95% CI, 2.1 to 3.5) for men with volumes greater than 60 cc (n = 272) on the Quasi-IPSS Scale (range 0 to 30). Similarly, improvements in peak urinary flow rate ranged from 0.89 mL/s (95% CI, -0.05 to 1.83) for men with prostate volumes less than 20 cc to 1.84 mL/s (95% CI, 1.37 to 2.30) in men with volumes greater than 60 cc. The difference in the magnitude of improvement between finasteride and placebo becomes significant (that is, no overlap in 95% CI) for men with a baseline prostate volume assessed by either transrectal ultrasonography or magnetic resonance imaging of greater than 40 cc, which encompasses approximately 50% of the entire population. Baseline prostate volume is a key predictor of treatment outcomes: approximately 80% of the variation in the treatment effects noted between studies could be attributed to differences in mean prostate volumes at baseline. Variation in entry criteria results in large differences in baseline symptom severity status, prostate volume, and consequently apparent inconsistencies in the overall outcomes of these trials.

CONCLUSIONS

This meta-analysis suggests that finasteride is most effective in men with large prostates. Men with small prostates may not be suitable candidates for finasteride therapy for BPH. The need for a careful reevaluation of the definitions and terminology used when discussing urination problems is apparent.

Vinyl fluoride as a mimic of the "intermediate' enol form in the 5 alpha-reductase transformation: synthesis and in vitro activity of (N-1',1'-dimethylethyl)-3-haloandrost-3,5-diene-17 beta-carboxamides

(N-1',1'-Dimethylethyl)-3-haloandrost-3,5-diene-17 beta-carboxamides (9-11) and the methyl ester 8 were prepared from 3-chloro/bromoandrost-3,5-diene-17 beta-carboxylic chloride/bromide (6/7), which were obtained from pregnenolone. In comparison with finasteride and 4-MA, compounds 8-11 showed very weak inhibitory activity ( < or = 10% inhibition) on human type I 5 alpha-reductase (transfected 293 cells) at 100 and 1000 nM concentrations. Against the type II enzyme, chloro compounds 8 and 9, and bromo 10 had no effect at 100 nM concentration, however, they were weak inhibitors of the type II (6.0% < inhibition < 30%) at a higher concentration. The best activity (IC50 = 480 nM) was observed with the 3-vinyl fluoride analogue 11.

Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a pathologic disorder that develops in response to the action of dihydrotestosterone on the aging prostate and to changes in stromal and epithelial cells in this exocrine gland. The current therapies for this disorder are chosen after other causes for irritative and obstructive symptoms have been excluded and the status of the urinary tract has been assessed. This evaluation includes a detailed medical history, a thorough genitourinary and neurological examination, assessment of serum prostate specific antigen and creatinine levels, as well as a urinalysis. A urodynamic evaluation consisting of a combined pressure-flow study is required if the diagnosis of obstruction is to be made. Patients with minimal symptoms and normal test results require no therapy. Mild to moderate symptoms can be controlled, at least temporarily, with alpha-adrenergic blockers such as terazosin or doxazosin. A subset of BPH patients with obstructive symptoms respond to the 5 alpha-reductase inhibitor finasteride. Early results with minimally invasive treatments such as laser prostatectomies, hyperthermia, and ultrasonic and radiofrequency ablation appear encouraging for those with moderate symptoms of prostatism. Severe symptoms, urinary retention, gross hematuria, recurrent urinary tract infections, bladder calculi, and hydronephrosis or renal insufficiency warrant transurethral incision, resection, vaporization, or open prostatectomy (for very large neoplasms). Although the morbidities of these latter surgical therapies are not insignificant, these treatments offer the best and most durable results for relief of obstruction and amelioration of symptoms.

Potential activities of androgen metabolizing enzymes in human prostate

The entire androgen metabolism of the human prostate is an integral part of the DHT mediated cellular processes, which eventually give rise to the androgen responsiveness of the prostate. Therefore, the potential activities of various androgen metabolizing enzymes were studied. Moreover, the impact of aging on the androgen metabolism and the inhibition of 5 alpha-reductase by finasteride were studied. In epithelium (E) and stroma (S) of normal (NPR) and hyperplastic human prostate (BPH), for each enzyme being involved in the conversion either of testosterone via DHT, 3 alpha- and 3 beta-diol to the C19O3-triols or from testosterone to androstenedione and vice versa, the amount (Vmax) and Michaelis constant (Km) were determined by Lineweaver-Burk plots. Furthermore, Vmax/Km quotients were calculated, which served as an index for the potential enzyme activity. 17 enzymes showed a mean Vmax/Km > or = 0.10. The top four were the 5 alpha-reductases in E and S of NPR and BPH. Among those, the highest activity was found in E of NPR (1.6 +/- 0.2). Moreover, in E a significant age-dependent decrease of 5 alpha-reductase activity occurred, whereas in stroma rather constant activities were found over the whole age range. Similar age-dependent alterations were found for the cellular DHT levels. Finally, the finasteride inhibition of 5 alpha-reductase (IC50;nM) was stronger in E (35 +/- 17) than in S (126 +/- 15). In conclusion, 5 alpha-reductase is: (a) the outstanding androgen metabolizing enzyme in NPR and BPH; (b) dictating the DHT enrichment in the prostate; (c) under the impact of aging; and (d) preferentially inhibited by finasteride in E.