5 alpha-reductase inhibition by finasteride (Proscar) in epithelium and stroma of human benign prostatic hyperplasia

Light-controlled calcium signalling in prostate cancer and benign prostatic hyperplasia

Background

Identifying ways to reduce the burden of prostate cancer (Pca) or benign prostatic hyperplasia (BPH) is a top research priority. It is a typical entanglement seen in men which is portrayed by trouble in micturition. It stands as a significant problem in our society. Different molecular biomarker has high potential to treat Pca or BPH but also causes serious side effects during treatment.

Main text

The role of calcium signalling in the alteration of different biomarkers of Pca or BPH is important. Therefore, the photoswitch drugs may hold the potential to rebalance the altered calcium signaling cascade and the biomarker levels. Thereby play a significant role in the management of Pca and BPH. Online literature searches such as PubMed, Web of Science, Scopus, and Google Scholar were carried out. The search terms used for this review were photo-pharmacology, photo-switch drug, photodynamic therapy, calcium signalling, etc. Present treatment of Pca or BPH shows absence of selectivity and explicitness which may additionally result in side effects. The new condition of the calcium flagging may offer promising outcomes in restoring the present issues related with prostate malignancy and BPH treatment.

Conclusion

The light-switching calcium channel blockers aim to solve this issue by incorporating photo-switchable calcium channel blockers that may control the signalling pathway related to proliferation and metastasis in prostate cancer without any side effects.

Graphical abstract

Schematic diagram explaining the proposed role of photo-switch therapy in curbing the side effects of active drugs in Pca (prostate cancer) and BPH (benign prostatic hyperplasia). a) Delivery of medication by ordinary strategies and irreversible phototherapy causes side effects during treatment. Utilization of photo-switch drug to control the dynamic and inert condition of the medication can cause the medication impacts as we required in prostate cancer and BPH. b) Support of harmony between the calcium signaling is essential to guarantee ordinary physiology. Increment or abatement in the dimensions of calcium signaling can result in changed physiology. c) Major factors involved in the pathogenesis of BPH; downregulation of vitamin D receptor (VDR) and histone deacetylase (HDAC) can prevent BPH. Similarly, downregulation of α-1 adrenoceptor can reduce muscle contraction, while overexpression of β-3 adrenoceptor in BPH can promote further muscle relaxation in BPH treatment therapy. Inhibition of overexpressed biomarkers in BPH TRPM2-1: transient receptor potential cation channel subfamily M member 1; TRPM2-2: transient receptor potential cation channel subfamily M member 2; Androgens; CXCL5: C-X-C motif chemokine ligand 5; TGFβ-1: transforming growth factor β-1; TXA2; thromboxane-2; NMDA: N-methyl-d-aspartate can be the potential target in BPH therapy.

Bioactives in Chinese Proprietary Medicine Modulates 5α-Reductase Activity and Gene Expression Associated with Androgenetic Alopecia

Androgenetic alopecia (AGA) is characterized by a progressive and patterned transformation of thick, pigmented terminal scalp hairs into short, hypo-pigmented vellus-like hairs. The use of Minoxidil and Finasteride to treat AGA are often associated with complications in safety and efficacy. However, herbal remedies are deemed to have lesser side effects in many societies. This study aims to identify potential hair growth properties of individual compounds from a Chinese proprietary medicine known as Yangxue Shengfa capsule (YSC), used in China for many years for improving AGA. Six marker compounds, including 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (TSG), Chlorogenic acid, Emodin, Ferulic acid, Isoimperatorin, and Paeoniflorin were used for simultaneous HPLC quantification and anti-AGA in-vitro screening. Simultaneous quantification of these components was performed on 75% (v/v) methanol extracts of YSC, using a Welch Ultimate XB-C18 column and gradient elution. Five compounds significantly promoted cell proliferation in cultured immortalized human Dermal Papilla Cells (DPC). Multiple genes associated with the progression of AGA, including IGF-1, DKK-1, and TGF-β1, were found to be regulated by some of these compounds. Interestingly, Ferulic acid and Emodin demonstrated good pharmacological properties against AGA, thereby concluding the potential of these bioactives to be used in the treatment against AGA.

Promising molecular targets and biomarkers for male BPH and LUTS

Benign prostatic hyperplasia (BPH) is a major health concern for aging men. BPH is associated with urinary voiding dysfunction and lower urinary tract symptoms (LUTS), which negatively affects quality of life. Surgical resection and medical approaches have proven effective for improving urinary flow and relieving LUTS but are not effective for all men and can produce adverse effects that require termination of the therapeutic regimen. Thus, there is a need to explore other therapeutic targets to treat BPH/LUTS. Complicating the treatment of BPH/LUTS is the lack of biomarkers to effectively identify pathobiologies contributing to BPH/LUTS or to gauge successful response to therapy. This review will briefly discuss current knowledge and will highlight new studies that illuminate the pathobiologies contributing to BPH/LUTS, potential new therapeutic strategies for successfully treating BPH/LUTS, and new approaches for better defining these pathobiologies and response to therapeutics through the development of biomarkers and phenotyping strategies.

Pathogenic role of HIF-1α in prostate hyperplasia in the presence of chronic inflammation

Benign prostatic hyperplasia (BPH) commonly occurs in older men with chronic prostatitis. Although BPH is frequently accompanied by inflammation, it is unclear whether inflammation underlies prostate enlargement. Recently, we reported that hypoxia-inducible factor 1α (HIF-1α), which is known to be induced by proinflammatory cytokines, is involved in testosterone-induced prostate hyperplasia. Therefore, we hypothesized that cytokines secreted from infiltrated macrophages under inflammatory conditions stimulate prostate enlargement by up-regulating HIF-1α. In the present study, we injected lipopolysaccharide (LPS) into rat prostates to mimic prostatitis and evaluated prostate hyperplasia 14days later. Epithelial cells of LPS-treated prostates were found to be highly proliferative and HIF-1α levels in prostate tissues to be elevated. When prostate epithelial cells were incubated in conditioned medium from macrophages activated with LPS, they robustly expressed HIF-1α, and under these conditions IL-1β, IL-6, and TNF-α cytokines were found to mediate HIF-1α induction. In addition, HIF-1α was found to enhance the expression of Twist, which initiates epithelial-mesenchymal transition (EMT). Furthermore, profound EMT features were observed in LPS-treated rat prostates, and the natural HIF-1α inhibitors ascorbate and curcumin were found to attenuate EMT and prostate hyperplasia both in vivo and in vitro. Based on these results, we propose that HIF-1α mediates prostate enlargement under inflammatory conditions, and we suggest that HIF-1α be viewed as a promising target for blocking the transition from prostatitis to BPH.

Prevention of Hormone-Related Cancers: Prostate Cancer

Androgens are known to play an important role in normal prostate development, benign prostatic hyperplasia, established prostate cancer, and in prostate carcinogenesis. However, despite convincing experimental and clinical evidence, the epidemiologic data correlating sex steroid levels with disease risk is inconsistent. More recent work has focused on studies of polymorphisms in germ-line DNA in an effort to develop polygenic models of prostate cancer susceptibility and prognosis. Such models have the potential to aid in the selection of men for specific chemopreventive interventions and to help determine which men with localized prostate cancer are most likely to benefit from aggressive therapy. In this review, we will provide a brief summary of androgen metabolic pathways followed by an assessment of the epidemiology literature addressing the relationship between androgens and prostate cancer. Finally, we will address the two major questions that have arisen in response to the recently published results from the Prostate Cancer Prevention Trial: Who are the best candidates for finasteride chemoprevention, and what are the clinical implications of the high prevalence of prostate cancer that was detected in men with prostate-specific antigen levels in the so-called “normal” range?

5 Alpha-reductase inhibitory and antiandrogenic activities of novel steroids in hamster seminal vesicles

The pharmacological activity of several 16-bromosubstituted trienediones 4 and 5, 16-methyl substituted dienediones 6 and 7 and the 16-methyl substituted trienedione 8 was determined on gonadectomized hamster seminal vesicles by measuring the in vitro conversion of testosterone (T) to dihydrotestosterone (DHT) as 5alpha-reductase inhibitors and also the ability of these steroids to bind to the androgen receptor. Steroids 6 and 7 when injected together with T decreased the weight of the seminal vesicles thus showing an antiandrogenic effect. Compounds 5 and 6 reduced substantially the conversion of T to DHT and therefore can be considered good inhibitors for the enzyme 5alpha-reductase; however both steroids failed to form a complex with the androgen receptor. On the other hand compound 7 which showed a very small inhibitory activity for the enzyme 5alpha-reductase, exhibited a very high affinity for the androgen receptor and thus can be considered an effective antiandrogen. This compound also reduced substantially the weight of the seminal vesicles. Steroids 4 and 8 did not reduce the weight of the seminal vesicles and exhibited a low affinity for the androgen receptor; 8 showed a weak 5alpha-reductase inhibitory activity, whereas 4 exhibited a weak androgenic effect.

Molecular quantum similarity-based QSARs for binding affinities of several steroid sets

The application of Molecular Quantum Similarity Measures (MQSM) to correlate biological activities for three different sets of steroids is reported. A general protocol for the generation of descriptors is detailed, thus covering molecular superposition, electronic density fitting, and quantum similarity calculation issues. Satisfactory Quantitative Structure-Activity Relationship (QSAR) models (r(2) in [0.69,0.94] and q(2) in [0.59,0.73]), comparable to previous studies, are obtained in all cases, where steroid binding affinities to different enzymes are studied. In this work, MQSM, properly scaled using Carbó Index, are related to activity using a Partial Least Squares routine.

Synthesis and pharmacological evaluation of new 16-methyl pregnane derivatives

The pharmacological activity of several new pregnane derivatives 15-19 were determined on gonadectomized male hamster flank organs, seminal vesicles and in vitro conversion of testosterone (T) to dihydrotestosterone (DHT) as 5alpha-reductase inhibitors. Steroids 15-19 decreased the diameter of the pigmented spot in the flank organs as compared to the T treated animals; in this model, steroids 16 and 19 showed a higher activity than the commercially available finasteride 3. Injection of T increased the weight of the seminal vesicles. Compounds 15-19 when injected together with T decreased the weight of the seminal vesicles thus showing an antiandrogenic effect. The trienone 19 exhibited a considerably higher activity than finasteride. Steroids 15-19 inhibited the in vitro metabolism of [3H]T to [3H]DHT in seminal vesicles homogenates of gonadectomized male hamsters. Compounds 18 and 19 showed a much higher antiandrogenic effect than finasteride. This enhancement of the biological activity could probably be attributed to the coplanarity of the steroidal skeleton as previously observed by our group. The high antiandrogenic activity of the epoxy compound 16 is probably the result of the ring opening of the oxiran ring with the nucleophilic part of the enzyme 5alpha-reductase thus leading to a stable adduct with concomitant deactivation of this enzyme.

Phospholipase A2 degradation products modulate epithelial and stromal 5alpha-reductase activity of human benign prostatic hyperplasia in vitro

BACKGROUND

Recent studies have demonstrated the inhibition of 5alpha-reductase activity in human prostate by phospholipases. Among those phospholipases, phospholipase A2 cleaves one of the acyl chains from phospholipids, thereby producing fatty acids and lysophospholipids such as LPC, LPS, and LPE. Therefore, we were interested in the effect of those lysophospholipids on 5alpha-reductase activity in human benign prostatic hyperplasia (BPH).

METHODS

In a first set of experiments, cell homogenates were incubated with phospholipase A2 either in the presence or absence of albumin, which is known to bind fatty acids and lysophospholipids. Thereafter, the effect of lysophospholipids of known structure on 5alpha-reductase activity was investigated.

RESULTS

In epithelium and stroma of human BPH, 5alpha-reductase activity was inhibited in a dose-dependent manner by phospholipase A2. In the presence of albumin, this inhibition was enhanced. In epithelium, LPC at low concentration yielded a dose-dependent stimulation of 5alpha-reductase activity up to 167%. At higher concentrations, epithelial as well as stromal 5alpha-reductase activity was inhibited significantly. As indicated by results of enzyme kinetic analyses, the LPC-mediated activation in the epithelium results from an increase of the active population of 5alpha-reductase. In contrast, LPC reduces the affinity of epithelial 5alpha-reductase to testosterone. LPE had no effect on epithelial 5alpha-reductase, whereas stromal 5alpha-reductase was inhibited in a dose-dependent manner up to 46%. Finally, LPS stimulated epithelial and stromal 5alpha-reductase activity; this stimulation was significantly stronger in epithelium (296%) than in stroma (163%). The LPC-mediated effects could be neutralized by the addition of albumin.

CONCLUSIONS

The present data on BPH tissue suggest that lysophospholipids may play a specific and structure-related role in the posttranslational regulation of human prostatic 5alpha-reductase.

QSARs for 6-azasteroids as inhibitors of human type 1 5alpha-reductase: prediction of binding affinity and selectivity relative to 3-BHSD

Quantitative structure-activity relationships (QSARs) are developed to describe the ability of 6-azasteroids to inhibit human type 1 5alpha-reductase. Models are generated using a set of 93 compounds with known binding affinities (K(i)) to 5alpha-reductase and 3beta-hydroxy-Delta(5)-steroid dehydrogenase/3-keto-Delta(5)-steroid isomerase (3-BHSD). QSARs are generated to predict K(i) values for inhibitors of 5alpha-reductase and to predict selectivity (S(i)) of compound binding to 3-BHSD relative to 5alpha-reductase. Log(K(i)) values range from -0.70 log units to 4.69 log units, and log(S(i)) values range from -3.00 log units to 3.84 log units. Topological, geometric, electronic, and polar surface descriptors are used to encode molecular structure. Information-rich subsets of descriptors are identified using evolutionary optimization procedures. Predictive models are generated using linear regression, computational neural networks (CNNs), principal components regression, and partial least squares. Compounds in an external prediction set are used for model validation. A 10-3-1 CNN is developed for prediction of binding affinity to 5alpha-reductase that produces root-mean-square error (RMSE) of 0.293 log units (R(2) = 0.97) for compounds in the external prediction set. Additionally, an 8-3-1 CNN is generated for prediction of inhibitor selectivity that produces RMSE = 0.513 log units (R(2) = 0.89) for the external prediction set. Models are further validated through Monte Carlo experiments in which models are generated after dependent variable values have been scrambled.

In vitro modulation of steroid 5alpha-reductase activity by phospholipases in epithelium and stroma of human benign prostatic hyperplasia

Membrane components, such as phospholipids, play an important role in the regulation of prostatic 5alpha-reductase activity. To describe in more detail the impact of such regulation on 5alpha-reductase activity, epithelial and stromal cell homogenates of human BPH were treated with phospholipases to specifically alter the structure of cellular phospholipid components. Phospholipase A(2) (PLA(2)) was used to alter the structure of the nonpolar, hydrophobic region of the membrane bilayer. Various types of phospholipase C (PLC) affect the polar, hydrophilic region of phospholipids. In epithelium and stroma, 5alpha-reductase activity was dose-dependently inhibited by PLA(2) and PLC type III. In epithelium and stroma, the mean IC(50) values of PLA(2) were 9.4 +/- 1.1 and 13.9 +/- 2.6 [U/mg protein +/- SEM], respectively. The mean IC(50) values of PLC type III in epithelium and stroma were 4.5 +/- 1.2 and 1.7 +/- 0.2 [U/mg protein +/- SEM], respectively. In epithelium as well as in stroma, 5alpha-reductase activity was more greatly inhibited by PLC type III than by PLA(2). Both in epithelium and stroma, PLA(2) significantly decreased the V(max) of 5alpha-reductase whereas its K(m) remained unaffected. A similar decrease in V(max) was found with PLC type III in epithelium and stroma. Furthermore, the K(m) of epithelial 5alpha-reductase increased significantly following the addition of PLC type III. The two phospholipases, with their specific substrate affinities and sites of hydrolysis, exhibited significantly different effects on 5alpha-reductase, indicating that 5alpha-reductase activity is not unspecifically affected by modification of the hydrophilic milieu. Rather, 5alpha-reductase activity is specifically modulated by various phospholipids and/or phospholipolysis mediated degradation products. These findings suggest that the structural composition of the lipid environment plays a fundamental role in the post-translational regulation of 5alpha-reductase activity in the epithelium and stroma of human BPH. Thus, changes in membrane phospholipid content seem to be instrumental in the expression of DHT-dependent processes.

In vitro inhibition of androstenedione 5alpha-reduction by finasteride in epithelium and stroma of human benign prostatic hyperplasia

Finasteride is a well known steroid 5alpha-reductase inhibitor. In this context, recently we have shown that in human benign prostatic hyperplasia (BPH) finasteride inhibits the 5alpha-reduction of testosterone to dihydrostestosterone (DHT) more effectively in the epithelium as compared to the stroma. The aim of the present study was to describe in epithelium and stroma of human BPH the effect of finasteride on the 5alpha-reduction of androstenedione, that is the second main circulating androgen in men, to androstanedione. Using a finasteride concentration of 75 nM and an androstenedione concentration of 220 nM, the mean inhibition [% +/- SEM] of 5alpha-reductase activity was significantly higher in epithelium (69 +/- 2) than in stroma (52 +/- 4). Both in epithelium and stroma, this inhibition of 5alpha-reductase activity was dose-dependent and competitive. Dixon plots as well as slope replots of Lineweaver-Burk plots showed that the mean inhibition constant Ki (nM +/- SEM) was significantly lower in epithelium (10 +/- 1 and 11 +/- 2, respectively) than in stroma (33 +/- 7 and 28 +/- 4, respectively) indicating a significantly stronger inhibitory effect of finasteride in epithelium. From those mean Ki values, it follows that in human BPH finasteride inhibits equally well both the 5alpha-reduction of androstenedione to androstanedione and testosterone to DHT. Based on these inhibition studies, there is no evidence for the coexistence of substrate-specific 5alpha-reductases converting either testosterone or androstenedione. However, the striking difference in finasteride sensitivity of the 5alpha-reduction between epithelium and stroma could be due to a cell-type specific expression of structurally different 5alpha-reductases as well as to a different access of finasteride to 5alpha-reductase in epithelium and stroma where, compared to each other, the lipid environment is significantly different.

Fatty acid composition of phospholipids in epithelium and stroma of human benign prostatic hyperplasia

BACKGROUND

Although it is well known that prostatic 5alpha-reductase is active only in its membrane-bound form, rather limited information is available concerning the composition of cellular lipids in human BPH. Therefore, in the present study, the phospholipid fatty acid composition and content in epithelium and stroma of human BPH have been investigated for the first time.

METHODS

Phospholipids separated on TLC plates were methylated and fatty acid methyl esters were analyzed by capillary gas chromatography.

RESULTS

The fatty acid composition of total phospholipids was significantly different between epithelium and stroma. In particular, the percentage of oleic acid was significantly higher in epithelium as compared with stroma, whereas that of arachidonic acid was significantly lower in epithelium than in stroma. In addition, significant differences between epithelium and stroma were found in regard to the fatty acid composition of the main phospholipid subclasses. Another remarkable finding were the age-dependent changes of the fatty acid composition in human BPH.

CONCLUSIONS

This study shows that the fatty acid composition of phospholipids is significantly different between epithelium and stroma of human BPH. Furthermore, age-dependent alterations of the fatty acid composition were found. Further studies are needed to determine whether the endogenous hormonal milieu in the prostate modulates the fatty acid composition of the prostatic cells, as well as what impact such modulation could have on the properties of membrane proteins, i.e., enzymes like the 5alpha-reductase and receptors, which are thought to be affected by alterations in membrane fluidity or composition, or both.

Plasma androsterone/epiandrosterone sulfates as markers of 5 alpha-reductase activity: effect of finasteride in normal men

Plasma androsterone/epiandrosterone sulfates, dehydroepiandrosterone sulfate, dihydrotestosterone, testosterone, androstenedione, and cortisol were measured in three normal adult men before and following finasteride administration (5 mg/day). Plasma androsterone/epiandrosterone sulfates and dihydrotestosterone declined in parallel to 50% of basal levels with little change in either dehydroepiandrosterone sulfate, cortisol, or androstenedione. The results suggest that the direct measurement of plasma androsterone/epiandrosterone sulfates by enzyme-linked immunosorbent assay provide similar information to plasma dihydrotestosterone and therefore provide a simple alternative for the assessment of 5 alpha-reductase activity.

Kinetic analysis of androstenedione 5 alpha-reductase in epithelium and stroma of human prostate

In the human prostate, various androgen-metabolizing enzymes are present. Among these enzymes, testosterone 5 alpha-reductase seems to be dominant. However, androstenedione is also a potential substrate of the prostatic 5 alpha-reductase. To address the question of to what extent the reduction of androstenedione to androstanedione occurs, the present study describes in detail the kinetic characteristics (Km and Vmax) and possible age-dependent alterations of this enzymatic step in epithelium and stroma of the human prostate. In normal prostate (NPR), the mean Km (nM) and Vmax (pmol/mg protein.h) were about twofold higher in stroma (Km, 211; Vmax, 130) than in epithelium (Km, 120; Vmax, 56), whereas in the benign prostatic hyperplasia (BPH), the mean Km (nM; mean +/- SEM) and Vmax (pmol/mg protein.h; mean +/- SEM) were about sixfold higher in stroma (Km, 668 +/- 121; Vmax, 415 +/- 73) than in epithelium (Km, 120 +/- 10; Vmax, 73 +/- 8). In BPH, those differences between epithelium and stroma were highly significant (p < 0.001). However, the efficiency ratios (Vmax/Km) of neither BPH nor NPR showed any significant differences between epithelium (NPR, 0.47; BPH, 0.62 +/- 0.06) and stroma (NPR, 0.70; BPH, 0.63 +/- 0.05). With respect to age-related changes, only stroma showed a significant increase of Km (p < 0.01) and Vmax (p < 0.05) with age. In summary, in both epithelium and stroma of the human prostate, a 5 alpha-reductase converts in measurable amounts androstenedione to androstanedione. The kinetic data were, in part, different between epithelium and stroma; the reason for this difference remains unclear. In comparison to other metabolic conversions, such as testosterone to dihydrotestosterone and androstenedione to testosterone, it is unlikely that, in the human prostate, the adrenal androgen androstenedione contributes significantly to the formation of testosterone and, further, of dihydrotestosterone.

Pharmacological and molecular evidence for the expression of the two steroid 5 alpha-reductase isozymes in normal and hyperplastic human prostatic cells in culture

BACKGROUND

Whereas the embryological development of the human prostate is clearly dependent on steroid 5 alpha-reductase (5 alpha-R) type 2 expression, the respective expression of the two known isoforms (types 1 and 2) of 5 alpha-R in the adult human prostate remains unclear.

METHODS

5 alpha-R isoform mRNA expression (Northern blots and reverse transcriptase-polymerase chain reaction [RT-PCR]) and enzyme activity were studied in immortalized epithelial cells (NE) and in fibroblasts from normal (NF) or hyperplastic (BPHF) human prostates.

RESULTS

5 alpha-R activity (fmol/microgram DNA/hr) was 1.43 +/- 0.5 in NE, 10.7 +/- 4.7 in NF, and 79 +/- 37 in BPHF. mRNAs for both 5 alpha-R isoforms were expressed in the three cell types, as shown by Northern blot and RT-PCR analysis. LY306089, a selective 5 alpha-R type 1 inhibitor, strongly inhibited 5 alpha-R activity in all cell types (IC50: 10 nM), confirming the predominant expression of 5 alpha-R type 1 in these cells. Finasteride, a 5 alpha-R type 2 inhibitor, was less efficient (IC50: 45, 35, and 65 nM in NE, NF, and BPHF, respectively). In addition, the inhibition by finasteride decreased with serial subculture in NF only, suggesting an effect of age in culture on the expression of 5 alpha-R type 2 in these cells. SKF105657, also a 5 alpha-R type 2 inhibitor, was a poor inhibitor in this system.

CONCLUSIONS

These studies demonstrate that human prostate cells in culture express both isoforms of 5 alpha-R and suggest a balance in the expression of the two isoforms as a function of various regulatory factors.

Differential gene expression of steroid 5 alpha-reductase 2 in core needle biopsies from malignant and benign prostatic tissue

Androgens are implicated in the development of prostate cancer (CAP) and benign prostate hyperplasia. The conversion of testosterone to the more potent metabolite dihydrotestosterone by prostatespecific steroid 5 alpha-reductase type 2 (5 alpha-red2) is a key mechanism in the action of androgens in the prostate and is important in the promotion and progression of prostate diseases. Manipulation of the turnover of androgens is thus fundamental in the pharmacological treatment strategy. We have developed a sensitive solution hybridization method for quantification of the gene expression of 5 alpha-red2 in core needle biopsies of the prostate. The 5 alpha-red2-specific messenger RNA (mRNA) levels were measured in 50 human prostate transrectal ultrasound-guided core biopsies obtained from 31 outpatients (median age 72, range 67-88 yr) undergoing biopsy for diagnostic purposes. Significant differences were observed in the gene expression of 5 alpha-red2 between cancerous and noncancerous tissue. In the 14 biopsies judged cancerous, the median 5 alpha-red mRNA levels were 3.5 amol/ng total RNA compared with 12.0 amol/ng total RNA in the biopsies showing no cancer (P = 0.0018). The median 5 alpha-red2 mRNA level in noncancerous tissue was thus 3.4 times higher than in the cancerous specimens.

Clinical Experiment Comparing 3 Pharmacological Treatments of Benign Prostatic Hypertrophy: Terazosin Vs. Finasteride Vs. Terazosin + Finasteride

The tone of the smooth prostate muscle and the presence of hyperplastic tissue represent the dynamic and passive components respectively of the obstructive symptomatology present in benign prostatic hyperplasia (BPH). The contractile properties are mediated primarily by the alpha-1 type adrenergic receptors, which are found in great numbers in the stroma of the gland and in the prostatic capsule. The use of Terazosin, a selective alpha-1 blocker, has proved to be effective in the improvement of BPH symptoms associated with the hypertone of the smooth muscle. The assumption that androgens play an important role in hypertrophy of the prostate has introduced drugs into the treatment which are capable of blocking the synthesis and the action of testosterone and, in particular, dihydrotestosterone (DHT). Finasteride is an inhibitor of 5-alpha-reductase, the enzyme inside the prostatic epithelial cells which converts the testosterone into DHT. A multicentre study has therefore been carried out aimed at assessing, after 9 months treatment, the efficacy and tolerability of three pharmacological treatments: Terazosin, Finasteride and a combination of the two, in 146 patients with symptomatic BPH. Results of the study indicate that the drugs were well tolerated and that the efficacy in resolving the obstructive symptomatology was particularly accentuated and rapid in the groups treated with Terazosin, the action of which, in this respect, has proved to be more significant than that of Finasteride.

19-nor-10-azasteroids: a novel class of inhibitors for human steroid 5alpha-reductases 1 and 2

Steroid 5alpha-reductase is a system of two isozymes (5alphaR-1 and 5alphaR-2) which catalyzes the NADPH-dependent reduction of testosterone to dihydrotestosterone in many androgen sensitive tissues and which is related to several human endocrine diseases such as benign prostatic hyperplasia (BPH), prostatic cancer, acne, alopecia, pattern baldness in men and hirsutism in women. The discovery of new potent and selective 5alphaR inhibitors is thus of great interest for pharmaceutical treatment of these diseases. The synthesis of a novel class of inhibitors for human 5alphaR-1 and 5alphaR-2, having the 19-nor-10-azasteroid skeleton, is described. The inhibitory potency of the 19-nor-10-azasteroids was determined in homogenates of human hypertrophic prostates toward 5alphaR-2 and in DU-145 human prostatic adenocarcinoma cells toward 5alphaR-1, in comparison with finasteride (IC50 = 3 nM for 5alphaR-2 and approximately 42 nM for 5alphaR-1), a drug which is currently used for BPH treatment. The inhibition potency was dependent on the type of substituent at position 17 and on the presence and position of the unsaturation in the A and C rings. delta9(11)-19-Nor-10-azaandrost-4-ene-3,17-dione (or 10-azaestra-4,9(11)-diene-3,17-dione) (4a) and 19-nor-10-azaandrost-4-ene-3,17-dione (5) were weak inhibitors of 5alphaR-2 (IC50 = 4.6 and 4.4 microM, respectively) but more potent inhibitors of 5alphaR-1 (IC50 = 263 and 299 nM, respectively), whereas 19-nor-10-aza-5alpha-androstane-3,17-dione (7) was inactive for both the isoenzymes. The best result was achieved with the 9:1 mixture of delta9(11)- and delta8(9)-17beta-(N-tert-butylcarbamoyl)-19-nor-10-aza-4- androsten-3-one (10a,b) which was a good inhibitor of 5alphaR-1 and 5alphaR-2 (IC50 = 127 and 122 nM, respectively), with a potency very close to that of finasteride. The results of ab initio calculations suggest that the inhibition potency of 19-nor-10-azasteroids could be directly related to the nucleophilicity of the carbonyl group in the 3-position.

Lipid composition in epithelium and stroma of human benign prostatic hyperplasia

The lipid composition and concentration in human benign prostatic hyper-plasia (BPH) were investigated. The reason was to shed some light onto the lipid environment of cellular membranes, in which the epithelial and stromal 5 alpha-reductase of the human prostate have apparently to be embedded in order to gain an active state. The phospholipids were found to be the major portion (67% +/- 1.1) of total lipids in whole BPH homogenate, followed by cholesterol (29% +/- 1.1) and glyceride glycerols (4% +/- 0.9). In BPH epithelium, the lipid concentration related to wet weight and to protein was two to three-fold higher than in stroma. Assigning the lipid concentration on a per-cell basis (i.e., related to DNA), a significantly lower lipid concentration was found in the epithelium as compared to the stroma. In the stroma, a significantly higher phospholipid and lower cholesterol portion were found than in the epithelium. Moreover, sphingomyelin was found to comprise a higher portion in stromal than in epithelial phospholipids, whereas the percentage of phosphatidylserine was higher in the epithelial phospholipids. We discuss whether the significant differences in lipid concentration and composition between the epithelium and stroma of human BPH could have an impact on the activity of the membrane-bound 5 alpha-reductase, or whether such differences in the lipid environment are due to a different hormonal milieu in the epithelium and stroma of BPH.

Human prostatic cells in culture: different testosterone metabolic profile in epithelial cells and fibroblasts from normal or hyperplastic prostates

The prostate gland depends on androgens for its development and the maintainance of its differentiated structures and secretory function. We have characterized the metabolic pathways of testosterone in isolated epithelial (NE) and fibroblast cultured cells from normal (NF) and hyperplastic (BPHF) prostates, in order to provide a tool for the study of androgen function in the prostate in defined conditions. In NE, 5 alpha-reductase (5 alpha-R) is the predominant metabolic pathway whereas in NF 17 beta-hydroxysteroid dehydrogenase (17 beta-OHSDHase) is the main activity. However, 5 alpha-R in NF is 5-10-fold higher than in NE. Furthermore, a striking increase in both enzyme activities is observed in fibroblasts from hyperplastic prostates (5 alpha-R x 8; 17 beta-OHSDHase x 250 relative to NF). delta 4-androstenedione could serve as a reservoir for testosterone or could be a tentative protective mechanism directing testosterone metabolism towards an inactive molecule. In conclusion, human epithelial and stromal cells maintain in culture their main metabolic characteristics. The knowledge derived from these studies should facilitate the reconstitution and analysis of their interactions, which in vivo may modify their respective metabolism.

Effects of the sabal serrulata extract IDS 89 and its subfractions on 5 alpha-reductase activity in human benign prostatic hyperplasia

Extract from fruit of Sabal serrulata are used in the treatment of human benign prostate hyperplasia (BPH). Therefore, it is of interest whether this phytopharmacon has any influence on the androgen metabolism in the human prostate. It was found that the extract IDS 89 of Sabal serrulata inhibited dose dependently 5 alpha-reductase activity in the epithelium and stroma of human BPH, the mean inhibition being 29% and 45%, respectively. This inhibitory effect is mainly due to the saponifiable subfraction of IDS 89 showing a mean 5 alpha-reductase inhibition of 39% and 38% in epithelium and stroma, respectively. The inhibition was dose dependent and noncompetitive. At a testosterone concentration of 580 nM as substrate for 5 alpha-reductase, the main fatty acids of the extract IDS 89 gave rise to a percentual enzyme inhibition in the epithelium and stroma as follows: 51% and 42% (lauric acid), 5% and 0% (oleic acid), 43% and 34% (myristic acid), 2% and 0% (palmitic acid), respectively. The inhibitory effect of lauric acid was noncompetitive and dose dependent up to a concentration of 0.2 nM, the maximal inhibition in the epithelium and stroma being 52% and 45%, respectively. The nonsaponifiable subfraction, consisting mainly of phytosterols, showed a mean inhibition of 5 alpha-reductase in the epithelium and stroma of 15% and 10%, respectively. Finally, the hydrophilic subfraction, containing carbohydrates, amino acids, and polysaccharides, showed no inhibitory effect. The present in vitro studies suggest that the Sabal serrulata extract IDS 89 has an inhibitory effect on 5 alpha-reductase in the epithelium and stroma of human BPH. This inhibition is mainly due to the fatty acids of the saponifiable subfraction.

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.