Stroma Of Benign Prostatic Hyperplasia Research Articles

Single-voxel oversampled J-resolved spectroscopy of in vivo human prostate tissue.

Single-voxel J-resolved spectroscopy with oversampling in the F1 dimension was used to obtain water unsuppressed 1H spectra of in situ human prostate tissue in 40 previously untreated prostate cancer patients. Based on T2-weighted MRI and previous biopsy information, voxels were placed in regions of benign or malignant peripheral zone tissue, or in regions of predominantly glandular or stromal benign prostatic hyperplasia (BPH) within the central gland. The addition of a second J-resolved dimension allowed for the observation of the J-modulation of citrate, as well as the resolution of polyamines from overlapping choline and creatine signals. Regions of healthy peripheral zone tissue and glandular BPH all demonstrated high levels of citrate and polyamines, with consistent coupling and J-modulation patterns. Conversely, regions of malignant peripheral zone tissue and stromal BPH demonstrated low levels of citrate and polyamines consistent with prior in vivo and ex vivo studies. Moreover, water T2 relaxation times determined for healthy peripheral zone tissue (mean 128 +/- 15.2 msec) were significantly different than for malignant peripheral zone tissue (mean 88.0 +/- 14.2 msec, P = 0.005), as well as for predominantly glandular (mean 92.4 +/- 12.2 msec, P = 0.009) and stromal BPH (mean 70.9 +/- 12.1 msec, P = 0.003). This preliminary study demonstrates that J-resolved spectroscopy of the in situ prostate can be acquired, and the information obtained from the second spectral dimension can provide additional physiologic information from human prostate tissue in a reasonable amount of time (< 10 min).

Magnetic resonance imaging and morphometric histologic analysis of prostate tissue composition in predicting the clinical outcome of terazosin therapy in benign prostatic hyperplasia

To determine whether magnetic resonance imaging (MRI) or quantitative color-imaged morphometric analysis (MA) of the prostate gland are related to the clinical response to terazosin. Thirty-six male patients with symptomatic benign prostatic hyperplasia (BPH) with a serum prostate-specific antigen level of 4-10 ng/mL underwent MRI with body coil, transrectal prostate ultrasonography and biopsy prior to terazosin therapy. For MRI-determined stromal and non-stromal BPH, the ratio of the signal intensity of the inner gland to the obturator internus muscle was evaluated. Histologic sections were stained with hematoxylin and eosin. The MA of the specimens was performed by Samba 2000. Results of the two techniques were interpreted according to the terazosin therapy results. The mean stromal percentage was 60.5 +/- 18.0%. No statistically significant relationship was found between the clinical outcome of terazosin and the MRI findings. The MA results showed a significant relationship between the percentage of stroma and the percent change of the peak urinary flow rate, but not with the percent change of the international prostate symptom score after terazosin therapy (P < 0.05). Magnetic resonance imaging alone is not sufficient in predicting the response to terazosin therapy. Morphometric analysis of BPH tissue composition can be used in predicting the clinical outcome of terazosin therapy but it is suitable only in patients for whom prostatic biopsy is necessary in order to rule out prostate cancer.

HEPARIN-BINDING EPIDERMAL GROWTH FACTOR-LIKE GROWTH FACTOR IS AN AUTOCRINE MEDIATOR OF HUMAN PROSTATE STROMAL CELL GROWTH IN VITRO

The physiological mechanisms by which soluble mediators of cell proliferation and survival alter expansion of the prostatic stroma in benign prostatic hyperplasia are poorly understood. We recently identified heparin-binding epidermal growth factor like growth factor (HB-EGF) as a product predominantly of the smooth muscle cell compartments of the adult human prostate. We assess the potential role of this growth factor as a stromal cell regulator. Primary cultures of desmin and alpha-actin positive human prostate stromal cells were shown to express several cell associated HB-EGF isoforms as well as the primary cognate HB-EGF receptor, ErbB1/HER1, suggesting the existence of an autocrine or juxtacrine regulatory loop. The related receptor tyrosine kinase, ErbB2/HER2, was also expressed as assessed by reverse transcriptase (RT) polymerase chain reaction (PCR). HB-EGF messenger RNA levels in human prostate stromal cells increased modestly (70%) in response to a repetitive mechanical stimulus, a lower response than has been reported for neonatal rat bladder smooth muscle cells, in which HB-EGF was originally identified as a mechanically responsive gene. HB-EGF, epidermal growth factor and basic fibroblast growth factor stimulated human prostate stromal cell growth, while a specific antagonist of HB-EGF, [Glu52]-diphtheria toxin/CRM197, inhibited human prostate stromal growth in serum-free medium by a mechanism that did not involve increased apoptosis. A function blocking antibody against CD9/DRAP27/MRP-1, a cell surface binding partner of the membrane form of HB-EGF, also stimulated human prostate stromal cell proliferation. HB-EGF is an endogenously produced human prostate stromal cell growth factor and, thus, may have a role as a physiologically relevant autocrine or juxtacrine mediator of stromal expansion in benign prostatic hyperplasia.

Autoradiographic Localisation and Contractile Properties of Prostatic Endothelin Receptors in Patients with Bladder Outlet Obstruction

Objectives: Previous studies have used endothelin (ET) receptor agonists and antagonists to localise ET receptor subtypes in prostatic tissue. We have utilised high affinity ET_A ([¹²⁵I]PD151242) and ET_B ([¹²⁵I]BQ3020) receptor–specific radioligands to determine the density and distribution of ET receptor subtypes in prostatic tissues obtained from patients with symptomatic benign prostatic hyperplasia (BPH). The contractile properties of the ET receptor subtypes as well as the effect of ET–1 on α₁–adrenergic receptor–mediated prostatic smooth muscle contraction were assessed. Patients and Methods: Saturation binding and quantitative autoradiographic studies were performed using specific radioligands for ET_A and ET_B receptors on prostate sections obtained from patients with bladder outflow obstruction secondary to BPH. In vitro isometric tension studies were carried out to characterise the ET receptor subtypes in prostatic smooth muscle strips from the same group of patients. In addition, the effect of ET–1 on α₁–adrenergic receptor–induced prostatic smooth muscle contraction was also investigated. Results: There were dense ET_A and ET_B receptor–binding sites in the prostatic stroma. ET_A receptor–binding sites were also prominent on the prostatic epithelium. ET–1 and sarafotoxin 6 c (ET_B receptor agonist) elicited prostatic smooth muscle contraction (–log EC₅₀ 8.31±0.15 and 8.22±0.22 M, respectively). Both BQ123 (ET_A antagonist) and BQ788 (ET_B antagonist) significantly inhibited ET–1– and S6c–mediated prostatic smooth muscle contractile responses, respectively. ET–1 at sub–threshold concentrations significantly enhanced α₁–adrenergic receptor–mediated prostatic smooth muscle contractile responses. Conclusions: ET_A receptor–binding sites are prominent in both prostatic stroma and epithelium, whereas ET_B receptor–binding sites were predominantly seen in the prostatic stroma in symptomatic BPH. Both ET_A and ET_B receptors mediate prostatic smooth muscle contraction. ET–1 enhances α₁–adrenergic receptor–mediated contractile responses, suggesting that ET may play a pathophysiological role in bladder outlet obstruction associated with BPH.

Effects of a new steroidal aromatase inhibitor, TZA-2237, and/or chlormadinone acetate on hormone-induced and spontaneous canine benign prostatic hyperplasia.

It has been known for many years that human benign prostatic hyperplasia (BPH) is composed predominantly of hyperplastic stromal cells rather than epithelial cells. In the present study the effects of a new steroidal aromatase inhibitor on hormone-induced and spontaneous canine BPH were investigated. (1) Effects of TZA-2237 on hormone-induced canine BPH. Ten castrated beagles were administered testosterone and androstenedione 6 days/week for 8 months, and divided randomly into three groups after 2 months of treatment as follows. Group I served as controls, Group II was given 0.5 and Group III was given 2.5 mg/kg/day TZA-2237 5 days/week for 6 months. (2) Effects of TZA-2237 on spontaneous canine BPH. Twenty aged beagles with BPH were divided into five groups, Group IV was untreated, Group V was treated with 1 and Group VI with 5mg/kg/day TZA-2237 5 days/week for 31 weeks. Group VII was treated with 5mg/kg/day Atamestane and Group VIII was treated with 0.3 mg/kg/day chlormadinone acetate (CMA) 5 days/week. (3) Effects of TZA-2237 combined with CMA on spontaneous canine BPH. Three aged beagles with BPH were treated with 1mg/kg/day TZA-2237 and 0.03 mg/kg/day CMA 5 days/week for 20 weeks (Group IX) and a further three aged beagles with BPH were treated with 0.3 mg/kg/day CMA alone 5 days/week (Group X). Hormone-induced prostatic growth was significantly suppressed in group III compared with that in other groups. In Group III, the intraprostatic aromatase activity, estradiol level and androgen receptor content decreased significantly in comparison with the values in Group I. The prostatic weights in Groups V, VI and VII increased significantly in comparison with the weight in Group IV. Serum LH and testosterone levels in Groups V, VI, and VII increased significantly in comparison with the level in Group IV. The prostatic weight in Group IX was decreased only slightly, but the smooth muscle component was decreased significantly. TZA-2237 is a new, unique and effective aromatase inhibitor that causes inhibition of both epithelial and stromal compartments in hormone-induced canine BPH. Dual inhibition of androgen and estrogen resulted in inhibition of smooth muscle growth, and should prove effective as a new method of treatment given the atrophic effects on not only the epithelium but also the stroma in human BPH.

Alpha 1-ADRENOCEPTOR ANTAGONISTS TERAZOSIN AND DOXAZOSIN INDUCE PROSTATE APOPTOSIS WITHOUT AFFECTING CELL PROLIFERATION IN PATIENTS WITH BENIGN PROSTATIC HYPERPLASIA

Purpose Recent evidence indicated that an alpha 1 blocker, doxazosin, induces prostate apoptosis in patients with benign prostatic hyperplasia (BPH). [1] in this study, to determine whether this apoptotic response was mediated by alpha 1 adrenoceptor-dependent mechanism or was specific to doxazosin, we examined the effect of another alpha 1 blocker, terazosin, in addition to doxazosin, on the dynamics of prostate cell growth. Materials and Methods Cell proliferation and apoptosis were evaluated in BPH patients, an untreated (control) group (n = 31), and men treated with terazosin (n = 42) and doxazosin (n = 61) for the relief of the obstructive symptoms. Terazosin (1 to 10 mg./day) and doxazosin (2 to 8 mg./day) treatment varied from 1 week to 3 years. Ki-67 immunostaining and the TUNEL assay were used to evaluate the proliferative and apoptotic indices, respectively, in both the epithelial and stromal components of prostate (biopsy and prostatectomy) specimens. The smooth muscle cell content of the prostatic stroma was identified on the basis of smooth muscle alpha-actin immunoreactivity. Results A significant induction of apoptosis was observed in both the prostatic epithelial and stromal cells within the first month of terazosin and doxazosin therapy, as compared with untreated controls (p <0.05). Furthermore, the marked induction of prostatic stroma apoptosis in response to both alpha 1 adrenoceptor antagonists was paralleled by a significant decrease in the smooth muscle alpha-actin expression. This loss of prostatic smooth muscle cells correlated with morphological stromal regression (as detected by trichrome staining) and BPH symptom improvement. Neither terazosin nor doxazosin therapy resulted in significant changes in prostate cell proliferation. Conclusions These findings demonstrated that alpha-blockers as a class may regulate prostate growth by inducing apoptosis in both the epithelial and stromal cells, with little effect on cell proliferation. Apoptosis-mediated prostate stromal regression appears as a molecular mechanism underlying the therapeutic response to alpha 1 blockade in the treatment of BPH.

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

Finasteride is a well known steroid 5 α-reductase inhibitor. In this context, recently we have shown that in human benign prostatic hyperplasia (BPH) finasteride inhibits the 5 α-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 5 α-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 5 α-reductase activity was significantly higher in epithelium (69±2) than in stroma (52±4). Both in epithelium and stroma, this inhibition of 5 α-reductase activity was dose-dependent and competitive. Dixon plots as well as slope replots of Lineweaver–Burk plots showed that the mean inhibition constant K i (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 K i values, it follows that in human BPH finasteride inhibits equally well both the 5 α-reduction of androstenedione to androstanedione and testosterone to DHT. Based on these inhibition studies, there is no evidence for the coexistence of substrate-specific 5 α-reductases converting either testosterone or androstenedione. However, the striking difference in finasteride sensitivity of the 5 α-reduction between epithelium and stroma could be due to a cell-type specific expression of structurally different 5 α-reductases as well as to a different access of finasteride to 5 α-reductase in epithelium and stroma where, compared to each other, the lipid environment is significantly different.

Stimulative effect of transforming growth factor-beta on collagen synthesis by human prostatic stromal cells in vitro.

Expression of transforming growth factor-beta (TGF-beta) in the prostate has been reported. The purpose of this study was to evaluate the effect of TGF-beta on collagen synthesis by stromal cells isolated from a patient with benign prostatic hyperplasia (BPH). Human prostatic stromal cells (HPSC) derived from BPH tissue were cultured in serum-free medium. After incubation with TGF-beta1, the concentration of procollagen type I C-peptide (PIP) in the HPSC-conditioned medium was measured by enzyme immunoassay while the concentration of procollagen type III N-peptide (PIIIP) was measured by radioimmunoassay. Per-cell production of each type of collagen was calculated by multiplying the measured concentration by the volume of medium and dividing by the number of harvested cells. One ng/mL of TGF-beta1 significantly (P < 0.05) increased collagen production by HPSC, to 220% and 120% of control for types I and III, respectively. Increasing the amount of TGF-beta1 to 10 ng/mL had no further effect. TGF-beta1 did not significantly affect HPSC number at concentrations of either 1 or 10 ng/mL. There was a strong correlation between PIP and PIIIP production (r = 0.929, P < 0.001). These findings suggest that TGF-beta1 stimulates accumulation of extracellular matrix in stromal BPH tissue without affecting proliferation of stromal cells.

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.

In vitro simulation of thermotherapy for benign prostatic hyperplasia by Fourier transform infrared microspectroscopy combined with differential scanning calorimetry.

Thermo-dependent changes in the secondary structure of the epithelium and stroma of benign prostatic hyperplasia (BPH) were investigated by Fourier transform infrared (FT-IR) microspectroscopy combined with differential scanning calorimetry (DSC). This microscopic FT-IR/DSC system was used to simulate transurethral thermotherapy for BPH in vitro. The results indicate that thermal-induced conversion from an alpha helix to a beta structure was found in the epithelium and stroma of BPH. However, this thermal-induced conversion behavior in the stroma was less sensitive than that in the epithelium during thermal treatment. The different thermal response between the epithelium and stroma of BPH might be due to the different constitutions of the epithelium and stroma of BPH.

Effects of the Sabal serrulata extract IDS 89 and its subfractions on 5α-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.

Effect of aging on endogenous level of 5 alpha-dihydrotestosterone, testosterone, estradiol, and estrone in epithelium and stroma of normal and hyperplastic human prostate.

It is widely believed that benign prostatic hyperplasia (BPH) is associated with aging. Thus, the question arises whether or not a correlation exists between the well known prostatic androgen and estrogen accumulation and aging. To address this question, we measured 5 alpha-dihydrotestosterone (DHT), testosterone, estradiol, and estrone in epithelium and stroma of six normal (NPR) and 19 BPH and correlated the values with the age of the donors (26-87 yr). The mean DHT level in NPR epithelium was significantly higher than in NPR stroma, and also significantly higher than in epithelium and stroma of BPH. The epithelial DHT level of NPR and BPH decreased with age, the correlation being statistically significant. The stromal DHT level of NPR and BPH showed no correlation with age. Concerning testosterone, generally rather low values were found which showed no correlation with age. The mean levels of estradiol and estrone were significantly higher in BPH stroma as compared to BPH epithelium as well as to NPR epithelium and stroma. In NPR, the mean levels of estradiol and estrone were significantly higher in epithelium than stroma. In NPR and BPH, the stromal estradiol and estrone levels increased significantly with age. In epithelium such a correlation between the estrogen levels and age was not found. Our results indicate that the prostatic accumulation of DHT, estradiol, and estrone is in part intimately correlated with aging, leading with increasing age to a dramatic increase of the estrogen/androgen ratio particularly in stroma of BPH.

17β-Hydroxysteroid oxidoreductase in epithelium and stroma of human prostate

It is conceivable that androstenedione contributes indirectly to 5α-dihydrotestosterone formation in human prostate by its intraprostatic conversion to testosterone. This reversible conversion is catalyzed by the enzyme 17β-hydroxysteroid oxidoreductase (17β-HSOR). At present, rather limited information on kinetic parameters like specific concentration ( V max), affinity to steroid substrates ( K m S ) and to pyridine nucleotides ( K m N ) of 17β-HSOR is available. Thus, we determined those aforementioned kinetic parameters in epithelium and stroma of normal human prostate (NPR) and benign prostatic hyperplasia (BPH). The main results were: (1) the mean K m s of 17β-HSOR red/NADPH was significantly ( P < 0.0001) lower than those of all other 17β-HSORs. (2) In almost all cases the mean V max was higher in BPH than NPR. (3) In all cases, the mean V max K m S ratios of 17β-HSOR red were higher than those of 17β-HSOR ox. The highest ratio was found regarding 17β-HSOR red/NADPH in BPH stroma. (4) In stroma, a significantly positive correlation of V max K m S of 17β-HSOR red/NADPH with age was found. (5) The lowest K m N was found regarding NADP +, followed by NADPH. It is concluded that in human prostate the balance of the reversible conversion of testosterone to androstenedione is shifted potentially towards testosterone, particularly in BPH stroma.

Influence of hormone application by subcutaneous injections or steroid‐containing silastic implants on human benign hyperplastic prostate tissue transplanted into male nude mice

To study the influence of androgens and estrogens on human benign prostatic hyperplasia (BPH) tissue, BPH fragments were grafted subcutaneously (s.c.) into male nude mice. Testosterone alone (group I) or in combination with 17 beta-estradiol (group III) were administered either by s.c. injections as oil suspensions or continuously by s.c. implanted steroid-containing Silastic implants (groups II and IV). Intact mice without transplants and treatment served as a control (group V). After 4 weeks of treatment, animals were exsanguinated, transplants were removed, and serum was obtained. Ninety-six percent of the BPH fragments were located; they displayed histologically typical BPH acini and stroma. In transplants of all treatment groups, the majority of secretory, as well as basal, cells displayed a proliferation comparable to the original tissue. In glandular cells of all transplants, prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) could be demonstrated immunohistochemically. Specimens removed from animals bearing testosterone implants displayed a very well preserved ultrastructure that was found less frequently in samples from injection-treated animals. Acini-bearing metaplastic epithelium were more often present in transplants treated by steroid injections and seemed to be due to lower androgen or higher estrogen serum levels. Endogenous serum testosterone levels (ng/ml +/- SD; n) were lower and more variable (i.e., higher standard deviation) in groups treated by injections (group I: 3.68 +/- 2.12; n = 5 and group III: 3.86 +/- 1.13; n = 5) and were similar to those seen in intact controls (3.93 +/- 1.62; n = 6) compared with groups treated by Silastic implants (group II: 5.11 +/- 1.14; n = 10 and group IV: 10.20 +/- 0.52; n = 4). These results indicate that by application of steroids via Silastic implants, reproducible hormone effects can be obtained on BPH tissue transplanted into male nude mice, thus providing a reliable new model system for study.

5α-androstane-3β,17β-diol hydroxylating enzymes in stroma and epithelium of human benign prostatic hyperplasia (BPH)

As enzymatic hydroxylation of 5α-androstane-3β,17β-diol (3β-diol) may be a factor in controlling the 5α-dihydrotestosterone (DHT) content in the prostate, we were interested in activity and distribution of these enzymes in epithelium and stroma of human benign prostatic hyperplasia (BPH). The enzyme activities were measured after mechanical separation of BPH tissue from 15 patients of various ages into stroma and epithelium, and optimization of the in vitro transformation of 3β-diol to hydroxylated products, which were analyzed by HPLC. The main results were: (1) 3β-diol was hydroxylated at C-7α-, C-7β, C-6α-, and C-6β. (2) The mean Michaelis constant K m (nM ± SEM) for hydroxylation at C-7α-(β) (168 ± 21) was significantly lower than at C-6α-(β) (601 ± 43) without differences between stroma and epithelium. (3) Hydroxylation at a position dominated significantly over that at β. (4) The mean maximal metabolic rate V max (pmol · mg protein −1·h −1) of hydroxylation at C-6α- was about 7-fold lower in stroma (3.4 ± 0.2) than in epithelium (23.8 ± 4.1), concerning the other hydroxylations, V max was about 1.6-fold lower in stroma. (5) With increasing age of the patients there was a significant decrease of the 3β-diol hydroxylation in stroma and epithelium. It is discussed that the significantly lower activity of 3β-diol hdyroxylation in stroma compared to epithelium and the decrease of activity with increasing age might potentiate the DHT accumulation in stroma of BPH.

Inhibition of androgen metabolism in stroma and epithelium of the human benign prostatic hyperplasia by progesterone, estrone, and estradiol.

It has been shown that progesterone, estrone, and estradiol are present in significant amounts in the human benign prostatic hyperplasia (BPH). Therefore it was of interest to determine the inhibitory effect of these steroids on the 5 alpha-reductase and 3 alpha (beta)-hydroxysteroiddehydrogenase (HSDH) activities, the enzymes responsible for the conversion of testosterone to 5 alpha-dihydrotestosterone (DHT), and DHT to 3 alpha (beta)-androstanediols, respectively. The enzyme inhibition was analyzed in vitro by measuring the 5 alpha-reductase in the presence of either progesterone, estrone, or estradiol, using testosterone as substrate. The DHT was used as substrate for HSDH. The metabolites were quantified by t.l.c. The main results were as follows: (1) Concerning 5 alpha-reductase in BPH, the mean inhibitor constants (KI; microM) of progesterone, estrone, and estradiol were 0.11, 15.5, and 5.1, respectively. (2) Analyzing epithelium and stroma of BPH separately, the inhibition of 5 alpha-reductase resulted in nearly identical KI's. (3) Concerning HSDH in BPH, the mean KI's of progesterone, estrone, and estradiol were 169, 63, and 192, respectively. (4) Analyzing epithelium and stroma of BPH separately, the inhibition of HSDH led to nearly identical KI's. (5) The kinetic parameters (KM, Vmax) of the 5 alpha-reduction of progesterone and testosterone were nearly identical. These results led to the suggestion that the endogenous concentrations of progesterone, estrone, and estradiol have no significant inhibitory effect on the 5 alpha-reductase and HSDH in vivo. Furthermore, the nearly identical inhibitor constants found for both enzymes in epithelium and stroma of BPH indicate that in both compartments the 5 alpha-reductase and HSDH are qualitatively identical.

Androgens and estrogens: Their interaction with stroma and epithelium of human benign prostatic hyperplasia and normal prostate

Growth and integrity of human prostatic epithelium is strongly dependent upon the adjacent stroma. Furthermore, the human prostate is under the control of sex hormones. Both facts prompted us to compare epithelium with stroma of human benign prostatic hyperplasia (BPH) and normal prostate (NPR) concerning their metabolism, binding and tissue concentrations of androgens and estrogens. In vitro metabolism was analyzed by t.l.c., androgen and estrogen binding sites were determined by a charcoal adsorption technique, androgen and estrogen tissue concentrations were measured by RIA. The main results are--(1) Metabolism: BPH stroma shows 2-3 times higher 5 alpha-reductase activity than epithelium. This high 5 alpha-reductase activity in BPH stroma dictates the differences between unseparated BPH and NPR, in the former the 5 alpha-reductase activity being 2 times higher. The 3 alpha(beta)-hydroxysteroid dehydrogenase (HSDH) activity is more evenly distributed between stroma and epithelium of BPH and NPR. The ratios of 5 alpha-reductase to HSDH activity in the various tissue fractions indicate that the highest enzymatically regulated 5 alpha-dihydrotestosterone (DHT) enrichment must occur in BPH stroma. (2) Tissue concentrations: unseparated BPH contains 2.2 times more DHT than NPR. About 70% of the total DHT content is found in nuclear fractions, whereby the nuclear DHT content of BPH stroma is significantly higher than that of BPH epithelium. In addition, nuclei of BPH stroma contain significantly more estradiol than epithelial nuclei. (3) Binding: the androgen receptor is evenly distributed between epithelium and stroma of BPH, while the estrogen receptor is preferably assayed in BPH stroma. These studies indicate that the BPH stroma is not only a preferential tissue for 5 alpha-reductase activity and DHT enrichment but also for nuclear estradiol accumulation.

Endogenous androgen levels in epithelium and stroma of human benign prostatic hyperplasia and normal prostate.

5 alpha-Dihydrotestosterone (DHT) and 5 alpha-androstane-3 alpha, 18 beta-diol (3 alpha-diol) were extracted from epithelium and stroma of human benign prostatic hyperplasia (BPH) and of normal prostate and quantified by RIA. The main results were: (1) concerning the BPH, DHT is mainly located in the nuclear fraction of epithelium and stroma, whereas 3 alpha-diol was completely of extranuclear origin, (2) in the nuclei derived from BPH stroma the DHT content (7.1 +/- 0.88 pmol/mg DNA, mean +/- SEM [n = 14]) was significantly higher (P less than 0.01) than in the nuclei derived from BPH epithelium (3.8 +/- 0.38 pmol/mg DNA [n = 14]). The DHT content in the nuclear fraction derived from unseparated, i.e. whole tissue, was 5.6 +/- 0.60 pmol/mg DNA [n =14], (3) the biological significance of the overwhelming DHT accumulation in the stromal nuclei for the BPH tissue is reflected by a significant correlation between the DHT values in the nuclei from stroma and whole tissue (rs = 0.710, P less than 0.01) and (4) in four normal prostates the DHT content in the nuclear fraction of epithelium (1.3 +/- 0.37 pmol/mg DNA) and stroma (2.2 +/- 0.93 pmol/mg DNA) was significantly lower (P less than 0.01, each) compared with the respective BPH fraction. These data support earlier findings which indicate that the stroma of BPH is a preferential tissue for androgen metabolism.