Estrogen-induced morphological and immunohistochemical changes in stroma and epithelium of rat ventral prostate

Testosterone regulates smooth muscle contractile pathways in the rat prostate: emphasis on PDE5 signaling

Testosterone (T) plays a permissive role in the development of benign prostatic hyperplasia (BPH), and phosphodiesterase 5 inhibitors (PDE5is) have been found to be effective for BPH and lower urinary tract symptoms (LUTS) in clinical trials. This study investigated the effect of T on smooth muscle (SM) contractile and regulatory signaling pathways, including PDE5 expression and functional activity in prostate in male rats (sham-operated, surgically castrated, and castrated with T supplementation). In vitro organ bath studies, real-time RT-PCR, Western blot analysis, and immunohistochemistry were performed. Castration heavily attenuated contractility, including sensitivity to phenylephrine with SM myosin immunostaining revealing a disrupted SM cell arrangement in the stroma. PDE5 was immunolocalized exclusively in the prostate stroma, and orchiectomy signficantly reduced PDE5 immunopositivity, mRNA, and protein expression, along with nNOS and ROKβ mRNA, whereas it increased eNOS plus α(1a) and α(1b) adrenoreceptor expression in castrated animals. The PDE5i zaprinast significantly increased prostate strip relaxation to the nitric oxide donor sodium nitroprusside (SNP) in control but not castrated rats. But SNP alone was more effective on castrated rats, comparable with sham treated with SNP plus zaprinast. T supplementation prevented or restored all above changes, including SNP and zaprinast in vitro responsiveness. In conclusion, our data show that T positively regulates PDE5 expression and functional activities in prostate, and T ablation not only suppresses prostate size but also reduces prostatic SM contractility, with several potential SM contraction/relaxation pathways implicated. Zaprinast findings strongly suggest a major role for PDE5/cGMP in this signaling cascade. PDE5 inhibition may represent a novel mechanism for treatment of BPH.

Morphological alterations in the prostate stroma of rats submitted to chronic nicotine treatment

The stroma plays a fundamental role in the function of different glandular systems. In the prostate, the stroma is responsible for the development and maintenance of the differentiated state of the epithelium. Nicotine induces tobacco dependence and promotes morphological alterations in the epithelial compartment. However, its effects on the prostate stroma are unclear. The objective of this study was to evaluate the morphology of the stromal microenvironment in the ventral prostate lobe of rats submitted to chronic nicotine administration. Twenty rats (Rattus norvegicus) were divided into two groups: 10 animals received subcutaneous nicotine and 10 animals received physiological saline by the same route. After treatment, samples were collected from the ventral prostate lobe, processed and submitted to histology, histochemistry, and ultrastructural analysis by transmission and scanning electron microscopy. The level of circulating testosterone was also analyzed. The results showed a significant increase in the density of type I collagen (56.3% to 85.9%, P < 0.01) and a decrease in the density of type III collagen (43.7% to 14.1%, P < 0.01). In addition, there was a qualitative increase in elastic fibers and in the number of smooth muscle cells with a secretory phenotype. Circulating testosterone levels were significantly reduced (898.3 to 363.1 ng/mL, P < 0.01). The results showed that nicotine modifies different components of the prostate stroma, suggesting that this drug is a risk factor for morphofunctional alterations in the prostate gland.

Expression of proteinase-activated receptor-2 (PAR2) is androgen-dependent in stromal cell line (hPCPs) from benign prostatic hyperplasia

BACKGROUND

Growth properties of the prostate are regulated by a variety of hormones and growth factors. Benign prostatic hyperplasia (BPH) is characterized by abnormal epithelial and stromal proliferation. Varying androgen hormone levels in elderly men are correlated with abnormal proliferations of the prostate. Proteinase-activated receptor-2 (PAR2), a subtype of G-protein-coupled receptors, is known to induce multiple biological processes. It could also play a key role in the proliferation and metastasis of prostate cancer, but its effect on BPH pathogenesis is to a great extent unknown.

METHODS

Localization of PAR2 was determined both in pathologically altered and in normal prostate tissues by using immunohistochemical techniques. PAR2 activity was assessed by measuring changes in intracellular calcium [Ca(2+)](i) following stimulation of cultured stromal cells with a PAR2 agonist (trypsin) and a synthetic PAR2-activating peptide (AP). DHT-dependence of PAR2 expression in prostate cancer and prostatic stromal cell lines was examined with semi-quantitative and quantitative PCR. Cultured stromal cells (hPCPs) were stimulated with PAR2 AP and cell proliferation was determined through [(3)H]-thymidine incorporation.

RESULTS

In comparison to normal prostate, PAR2 expression was increased in BPH stroma. DHT induced a higher expression of PAR2 when sub-physiological DHT-levels were used. Higher levels of DHT produced reduced PAR2 expression. A mitogenic effect was induced by applying PAR2 AP to hPCPs-cells.

CONCLUSIONS

In conclusion, we found that PAR2 expression is hormone-dependent in prostatic stromal cells with a negative correlation and we consider it to be an important factor in mitogenesis in BPH.

Both nongenomic and genomic effects are involved in estradiol's enhancing the phenotype of smooth muscle cells in cultured prostate stromal cells

BACKGROUND

Stromal smooth muscle cells (SMCs) play an important role in the pathogenesis and clinical symptom of benign prostatic hyperplasia. We had reported that estrogen enhances the phenotype of SMC in cultured prostate stromal cells (PRSCs). Here we further investigate the mechanism by which estrogen affects the differentiation of PRSCs.

METHODS

Primary cultured PRSCs were stimulated with E2 or BSA-E2. The mRNA level of SMC-specific genes, smoothelin, and SM-MHC were measured by qRT-PCR. The SM-MHC protein was measured by Western blot. The mRNA and protein levels of TGF-beta1 were measured by qRT-PCR and ELISA. The MAPK inhibitor PD98059, the estrogen receptor antagonist ICI182,780 and neutralizing antibody to TGF-beta1 were used to reveal the mechanism of estrogen effect.

RESULTS

E2 and BSA-E2 significantly up-regulate the expression of SMC-specific genes in PRSCs. Both forms of estrogen could increase the expression of TGF-beta1, which can be blocked by pre-treating with PD98059. Moreover, PD98059 and TGF-beta1 neutralizing antibody could abrogate the effect of BSA-E2 on cell differentiation. However, they could only inhibit part of E2-induced SMC phenotype enhancement. ICI182,780 could partially suppress the pro-differentiation effect of E2 but had no influence on the effect of BSA-E2. Combined treatment with ICI182,780 and PD98059 can completely abrogate the effect of E2.

CONCLUSIONS

Estrogen could promote the expression of TGF-beta1 in PRSCs through nongenomic activation of MAPK pathway, and in turn enhance the SMC phenotype. Besides for this nongenomic effect, estrogen can also enhance the SMC phenotype through classical genomic action.

Oestrogen supplementation following castration promotes stromal remodelling and histopathological alterations in the Mongolian gerbil ventral prostate

The effect of oestradiol on the intact and castrated adult gerbil prostate was evaluated by focussing on stromal and epithelial disorders, and hormonal receptor immunoreactivity. The experimental animals were studied by histological, histochemical and immunohistochemical techniques, morphometric-stereological analysis and transmission electron microscopy. Epithelial alterations in the oestradiol-treated animals were frequent, with an increase in epithelial cell height, areas of intense dysplasia and hyperplasia and formation of prostatic intraepithelial neoplasia (PIN). Another aspect that did not depend on the presence of testosterone was the arrangement of the fibrillar and non-fibrillar elements of the extracellular matrix among smooth muscle cells (SMC), suggesting a possible role of these cells in rearrangement and synthesis of these components, after oestrogenic treatment. In the castrated animals, an accumulation of extracellular matrix elements under the epithelium was evident, while in the intact animals the same compounds were dispersed and scarce. In the groups of intact and castrated animals, SMC and fibroblasts exhibited a secretory phenotype, which was accentuated after oestradiol administration. There was an increase of the immunoreactivity to alpha-oestrogen and androgen receptors in hyperplastic areas compared to normal epithelium, revealing the involvement of these steroid receptors in the hyperplasia and PIN development.

Effects of long-term castration on the smooth muscle cell phenotype of the rat ventral prostate

Smooth muscle (SM) is an important component of the prostatic stroma. We previously showed that, despite extensive morphologic changes, smooth muscle cells (SMCs) of the rat ventral prostate preserve some differentiation markers 21 days after castration. In the present study, we investigated whether the expression of SMC markers is preserved in the rat ventral prostate after long-term castration. Adult Wistar rats were castrated and sacrificed 100 days after surgery. The ventral prostates were processed for histology, stereology, immunocytochemistry (SM alpha-actin and SM-myosin heavy chain [MHC]), transmission electron microscopy (TEM), and reverse transcription polymerase chain reaction (smoothelin, sm22, and calponin). The prostates of castrated rats showed significant weight reduction, corresponding to only 5.6% of the control. Stereology showed that SMCs occupied the same proportion of the prostate volume but suffered a significant reduction in absolute volume (5.5% of control). The SMCs were retracted and showed spinous outlines. TEM revealed the presence of an abundant myofibrillar component, dense plaques, and an external lamina in these cells. SMCs were reactive to antibodies against SM alpha-actin and SM-MHC and expressed mRNA for smoothelin, sm22, and calponin. The results confirmed that rat prostatic SMCs are affected by androgen deprivation. Although showing marked phenotypic changes, these cells expressed SMC markers at the protein (SM alpha-actin and SM-MHC) and mRNA (smoothelin, sm22, and calponin) levels. These observations support the idea that SMCs may modulate their phenotypes (contractile vs synthetic) without changing their differentiation states.

The distribution of oestrogen receptors in normal, hyperplastic and neoplastic canine prostate, as demonstrated immunohistochemically

The role of oestrogens and their receptors (ERs) in prostatic growth and differentiation and in the progression of prostatic carcinoma has been well investigated in human medicine. In dogs, however, available reports on the expression of ERs in normal, hyperplastic or neoplastic prostates are few and controversial, or completely lacking. Three normal, three hyperplastic and nine neoplastic canine prostates were examined histologically, and immunohistochemically with a polyclonal antibody directed against human ERs. Evaluation of the percentage of immunolabelled cells was performed by digital image analysis. The study showed that ERs were expressed in the nuclei of epithelial and stromal cells in normal, hyperplastic and neoplastic prostates. All nuclei in normal and hyperplastic prostates were strongly and homogeneously immunolabelled by the antibody used. However, the percentages of immunolabelled nuclei in the nine prostatic carcinomas were greatly reduced, ranging from 36.34% to 66.73%. The severe loss of ER expression in canine prostatic carcinomas may account for the relative lack of differentiation of these tumours in the dog.

Assessment of proliferative activity by AgNOR and PCNA in prostatic tissues of ram lambs implanted with zeranol

The aim of this study was to assess cellular proliferation using silver-stained nucleolar organizer regions (AgNOR) and the proliferating cell nuclear antigen (PCNA) in various tissues in the prostate of ram lambs implanted with increasing zeranol doses and to compare the sensitivity of different tissues of lamb prostate to zeranol. Twenty-four Akkaraman lambs were implanted with increasing zeranol doses, including 12 mg (n = 8), 24 mg (n = 8) and 96 mg (n = 8), with eight lambs serving as controls. After 33 days, the prostate tissues of the lambs were stained using AgNOR and PCNA techniques. The prostate tissues were divided into two compartments--the epithelial tissues, including glandular acinus, collecting duct and penile urethra, and the non-epithelial tissues, including interstitial tissue and striated muscle. AgNOR dots and PCNA index on each prostatic tissue were counted under a light microscope and were evaluated statistically. AgNOR staining in the treatment groups showed a higher score in the non-epithelial tissues than the epithelial components, whereas the PCNA index was significant in the epithelial tissues and non-epithelial tissues had very low PCNA immunostaining. According to the PCNA index, collecting duct epithelium showed more sensitivity to increasing zeranol doses and according to AgNOR counts, there was no difference of sensitivity to zeranol among tissues of the same origin. Both AgNOR counts and PCNA indexes seem to be valuable proliferating markers for the epithelial components of ram prostate, but PCNA index had no significance in relation to the non-epithelial components in contrast to AgNOR counts. Therefore, the controversial results arising from the combined use of both techniques as proliferating markers for the ram prostate should be considered in further studies.

Early effects of estrogen on the rat ventral prostate

Complex interactions between androgen and estrogen (E2) regulate prostatic development and physiology. We analyzed the early effects of a high single dose of E2 (25 mg/kg body weight) and castration (separately or combined) on the adult 90-day-old male Wistar rat ventral prostate. Androgen levels, prostate weight, and the variation in the relative and absolute volume of tissue compartments and apoptotic indices were determined for 7 days. Castration and exogenous E2 markedly reduced ventral prostate weight (about 50% of the control), with a significant reduction in the epithelial compartment and increased stroma. The final volume of the epithelium was identical at day 7 for all treatments (58.5% of the control). However, E2 had an immediate effect, causing a reduction in epithelial volume as early as day 1. An increase in smooth muscle cell volume resulted from the concentration of these cells around the regressing epithelium. The treatments resulted in differential kinetics in epithelial cell apoptosis. Castration led to a peak in apoptosis at day 3, with 5% of the epithelial cells presenting signs of apoptosis, whereas E2 caused an immediate increase (observed on day 1) and a sustained (up to day 7) effect. E2 administration to castrated rats significantly increased the level of apoptosis by day 3, reaching 9% of the epithelial cells. The divergent kinetics between treatments resulted in the same levels of epithelial regression after 7 days (approximately 30% of control). These results show that E2 has an immediate and possibly direct effect on the prostate, and anticipates epithelial cell death before reducing testosterone to levels as low as those of castrated rats. In addition, E2 and androgen deprivation apparently cause epithelial cell death by distinct and independent pathways.

Smooth muscle cell behavior in the ventral prostate of castrated rats

Smooth muscle cells (SMC) play roles in prostatic development and function. The cells also respond to tissue injury and hormonal variations, alternating between a fully differentiated and contractile phenotype and a dedifferentiated synthetic or secretory phenotype. However, the phenotypic changes in SMC after androgen deprivation have not yet been described. The ventral prostate of control and castrated rats was processed for routine histology, immunocytochemistry, reverse transcriptase polymerase chain reaction (RT-PCR), and scanning electron microscopy (SEM). The maintenance of SMC phenotype was confirmed by immunocytochemistry and by RT-PCR. Stereological analyses were done to define the relative and absolute volume of the SMC. SMC were elongated and flattened against the epithelium. After castration, the cells shortened concomitantly with pleating of the cell surface, leading to a spinous aspect. SEM showed that the smooth surface of SMC became progressively folded. Immunocytochemistry demonstrated both smooth muscle myosin heavy chain and smooth muscle alpha-actin in the prostatic SMC 21 days after castration, whereas RT-PCR amplified the message for smoothelin. Stereological analysis showed an increase in the relative volume of SMC in relation to the whole gland and the stroma. A decrease in the absolute volume of SMC occurred only within the first 7 days after castration and remained unchanged thereafter. The prostatic SMC are affected by the absence of androgens and there is a critical transition point during the first week in which the total volume occupied by SMC diminished. The remaining SMC showed a marked phenotypical change. These findings indicate that ventral prostate SMC maintain their differentiated phenotype after castration. The alterations in SMC behavior correlate with general stromal modifications taking place after castration.

Structure, histochemistry, and ultrastructure of the epithelium and stroma in the gerbil (Meriones unguiculatus) female prostate

The female prostate has aroused scientific interest because it is subjected to the same diseases compromising the male prostate during aging. The objective of this work was to characterize structurally, cytochemically, and ultrastructurally the tissue compartments of the normal adult female prostate of Meriones unguiculatus gerbils. The morphological analyses showed that the gerbil's female prostate is constituted of a cluster of glands and ducts inserted in a musculofibrous stroma. The alveolar epithelium is differentiated and consisted of basal proliferating cells, intermediary cells, and secretory cells. The secretory cells are the most numerous cell type and continuously secrete glycoproteins. The basal cells are the source of the secretory cells and they are then responsible for the alveolus renovation. The prostatic stroma is abundant and rich in elastic and collagen fibers, which are closely associated with smooth muscle cells and fibroblasts. The results showed that the gerbil's female prostate shows morphological and ultrastructural homology to the human female prostate (Skene's gland), and despite being a small organ, it is a mature and physiologically active gland.

Inhibition of 5-α-reductase activity induces stromal remodeling and smooth muscle de-differentiation in adult gerbil ventral prostate

Prostatic differentiation during embryogenesis and its further homeostatic state maintenance during adult life depend on androgens. Dihydrotestosterone, which is synthesized from testosterone by 5 alpha-reductase (5 alpha-r), is the active molecule triggering androgen action within the prostate. In the present work, we examined the effects of 5 alpha-reductase inhibition by finasteride in the ventral prostate (VP) of the adult gerbil, employing histochemical and electron microscopy techniques to demonstrate the morphological and organizational changes of the organ. After 10 days of finasteride treatment at a dose of 100 mg/kg/day, the prostatic complex (VP and dorsolateral prostate) absolute weight was reduced to about 18%. The epithelial cells became short and cuboidal, with less secretory blebs and reduced acid phosphatase activity. The luminal sectional area diminished, suggestive of decreased secretory activity. The stromal/epithelial ratio increased, the stroma becoming thicker but less cellular. There was a striking accumulation of collagen fibrils, which was accompanied by an increase in deposits of amorphous granular material adjacent to the basal lamina and in the clefts between smooth muscle cells (SMC). Additionally, the periacinar smooth muscle became loosely packed. Some SMC were atrophic and showed a denser array of the cytoskeleton, whereas other SMC had a highly irregular outline with numerous spine-like projections. The present data indicate that 5 alpha-r inhibition causes epithelial and stromal changes by affecting intra-prostatic hormone levels. These alterations are probably the result of an imbalance of the homeostatic interaction between the epithelium and the underlying stroma.

Dedifferentiation of stromal smooth muscle as a factor in prostate carcinogenesis

We had earlier established an animal model of prostate carcinogenesis using a combination of testosterone (T) and 17beta-estradiol benzoate (E2) on Noble rats (Wang and Wong, 1998). In the present study we examined the changes in a number of smooth muscle differentiation markers including smooth muscle alpha-actin and myosin, vinculin, desmin, laminin and vimentin as well as changes in fine structure by electron microscopy. Our immunohistochemical (IHC) studies revealed that smooth muscle cells (SMCs) subjacent to dysplastic (precancerous) sites and carcinoma usually exhibited a preferential loss of myosin, desmin and laminin. However, the expression of alpha-actin and vinculin appeared to be more persistent in most dysplastic or neoplastic sites. The study reaffirmed our earlier observation that there was a concurrent dedifferentiation of surrounding SMCs during the development and progression of prostate carcinogenesis. The structural study revealed that SMC subjacent to epithelial dysplasia displayed a spectrum of derangements. These included the loosening of muscular layers with SMC characterized by their highly irregular external contours with numerous spine-like cytoplasmic projections. There was also a reduction in density of myofilaments and presence of many enlarged caveolae in muscle cells. Additionally, focal discontinuity or disruptions of muscular layer were often observed together with an increase in abundance of fibrous connective tissue. Moreover, the amount of smooth muscle appeared to be inversely correlated with the histologic grade of prostate tumors. In most instances, SMCs were totally absent in the moderately or poorly differentiated tumors and in metastatic tumors in the lung and the small intestine. Stromal muscular deformity was associated with concurrent changes in epithelial cells. Dysplastic epithelial cells were characterized by a reduction in abundance of secretory organelles such as reduction in size of Golgi apparatus, paucity of granular endoplasmic reticulum and secretory vesicles. The nuclei showed typical deformity characterized by deep nuclear membrane foldings. The basal lamina of dysplastic or tumor cells was present although focal structural abnormalities such as reduplication, disruption and smearing were sometimes observed. The present data indicate that derangements of epithelial cells during prostate carcinogenesis are associated with a reduction or dedifferentiation of stromal SMCs. Our results lend support to the hypothesis that transformed epithelium is incapable of maintaining normal differentiation of adjacent muscle. In turn, abnormal stromal, resulting from dedifferentiation or reduction of SMC, may lead to loss of stromal control over epithelial proliferation and differentiation. Consequently, a loss of differentiation in both epithelium and stromal SMCs may be critically involved in hormone-induced prostate carcinogenesis.

Bisphenol A inhibits penile erection via alteration of histology in the rabbit

Despite extensive research into the toxicity of bisphenol A (BPA), no report of its effect on erectile function exists. We performed this study to investigate the effect of BPA on erectile function. New Zealand white rabbits were treated intraperitoneally with 150 mg/kg of BPA every other day for 12 days (cumulative dose of 900 mg/kg). Four and 8 weeks after administration of BPA, the contractions and relaxation of cavernosal tissue strips were significantly suppressed in the BPA-treated animals compared to the control animals. Histologically, thickening of tunica albuginea, subtunical deposition of fat and decreased sinusoidal space with consequent increase of trabecular smooth muscle content were observed in the BPA-treated animals. These results suggest that xenoestrogen BPA may affect the erectile function through evident histological changes of the penis.

Proliferation and differentiation of prostatic stromal cells

OBJECTIVES

To investigate the effects of androgen, transforming growth factor beta1 (TGF-beta) and basic fibroblast growth factor (bFGF) on the proliferation and differentiation of prostatic stromal cells of the dog in vivo and human stromal cells in vitro.

MATERIALS AND METHODS

Twenty-two dogs had their serum concentration of testosterone and oestradiol determined by radioimmunoassay before and after castration. Light microscopy, transmission electron microscopy and an in situ cell-death assay were carried out successively before and after castration to evaluate prostatic histomorphology. A semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was used to evaluate the expression of TGF-beta, bFGF and myosin in the canine prostate tissue after castration. In vitro serum-free cell cultures from human prostatic stroma were established and exposed to dihydrotestosterone (DHT), TGF-beta and bFGF in various concentrations. The proliferation of the cell cultures was detected by the tetrazolium assay. The differentiation from fibroblasts to smooth muscle cells (SMCs) was deduced by measuring the expression of SMC-specific proteins (myosin and smoothelin) using immunohistochemistry and RT-PCR.

RESULTS

Castration resulted in a significant decrease in circulating testosterone levels (P < 0.01), but did not affect the circulating oestradiol levels (P > 0.05). The prostatic stromal cells, including SMCs and fibroblasts, diminished and underwent a serial pathological change of atrophy and apoptosis after castration. The atrophic cells were filled with intracellular lipofuscin. The expression of SMC myosin declined after castration, coincident with the increase in TGF-beta mRNA level and decline in bFGF mRNA. In vitro, TGF-beta inhibited the growth of human prostatic stromal cells during exponential growth, while enhancing myosin staining and stimulating the expression of smoothelin in confluent cultured stromal cells. bFGF stimulated the growth of the culture and inhibited the expression of smoothelin. DHT caused a weak increase in the proliferation and expression of SMC-specific proteins (P < 0.05). However, DHT and bFGF together stimulated the proliferation of stromal cells significantly more than either agent alone (P < 0.01). The combination of DHT and TGF-beta greatly enhanced the expression of SMC-specific proteins (P < 0.01), more strongly than either alone (P < 0.01).

CONCLUSIONS

The whole prostate gland is an androgen-sensitive organ, with both the epithelium and stroma under the control of androgen. Androgen may direct the proliferation and differentiation of prostatic stromal cells by regulating the expression of TGF-beta and bFGF. Thus DHT, TGF-beta and bFGF may have important roles in regulating stromal cell homeostasis.

Collagen fiber reorganization in the rat ventral prostate following androgen deprivation: a possible role for smooth muscle cells

BACKGROUND

Stroma plays an essential role in glandular function in different systems. In the prostate, it is responsible for the development and maintenance of the differentiated state of the epithelium. The marked reduction in the epithelial compartment of the prostate gland following castration is followed by a similarly important reorganization of the stroma. In this work, we characterized the reorganization of collagen fibers in the ventral prostate of castrated rats.

METHODS

Histochemical tests and immunohistochemistry for type I and III collagens plus confocal microscopy of triple-labeled (collagen III, actin, and DNA) tissue sections were employed.

RESULTS

We showed that collagen fibers are composed of type I and type III collagens and that they are progressively concentrated around the epithelial structures (ducts and acini) and become increasingly undulated and folded. Double-labeling of collagen fibers and F-actin demonstrated that smooth muscle cells (SMC) are intimately associated with collagen fibers.

CONCLUSIONS

The results demonstrated a marked reorganization of the collagen fibers, and suggest an active role of the SMC in the reorganization of the fibrillar components of the stroma.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Apocrine secretion--fact or artifact?

In this review, the history of apocrine secretion and the essential categories are briefly mentioned and fused into a more generally applicable terminology. Using the coagulating gland of the male rat as a model, the mechanisms of apocrine secretion, the participation of the cytoskeleton in the formation of the apocrine blebs ("aposomes") and the structure of the secretory proteins, as well as the hormonal regulation of their biosynthesis are described. Apocrine secreted proteins share the following peculiarities: (i) Their biosynthesis and post-translational modification (including an unusual form of glycosylation) take place in the cytoplasm. (ii) Intracellular transport proceeds without participation of the endomembrane system, the Golgi apparatus and secretion granules. (iii) Blood serum derived transsudated albumin entering the secretory cells functions as a carrier of the apocrine-released proteins. Some common molecular features are specific for the apocrine-synthesized proteins studied so far by our group: (a) Their primary sequence is synthesized without a signal peptide. (b) Their N-terminus is blocked by acetylation. (c) The substituting glycanes are neither O- nor N-linked. (d) At least one of the apocrine-synthesized proteins (secretory transglutaminase) contains a glycerol-phosphoinositol (GPI-) anchor. There are a number of still open questions in apocrine secretion, pertaining to (I) the intracellular transport and targeting of the proteins, (II) the coordination of simultaneously occurring apocrine and merocrine secretion in several of the apocrine glands, (III) the biosynthesis of the apical membrane proteins surrounding the aposomes and (IV) the repair mechanisms of the apical cell pole following the release of the aposomes. In conclusion, apocrine release is not an artifact but rather an alternative extrusion mechanism of soluble and membrane-associated proteins, usually linked with sex- or reproductive-related glands, such as the prostate, the mammary glands, apocrine sweat glands or epididymis.

Elastin gene expression in benign prostatic hyperplasia

BACKGROUND

Benign prostatic hyperplasia (BPH) is mainly a stromal process, showing an increased ratio of stromal to epithelial elements, a collagen type III downregulation, and a collagen types I and IV upregulation. Little is known about elastin gene expression in BPH tissues due to difficulties related to extensive alternative splicing of the elastin gene. Therefore, we analyzed and quantified elastin gene expression in BPH.

METHODS

A competitive reverse transcriptase-polymerase chain reaction (competitive RT-PCR) quantitative technique was used, and a quantitative elastin mRNA analysis with normal (n = 10) and BPH (n = 12) tissues was performed with two newly designed elastin primers. Small tissue samples (4-8 mg) were homogenized and sonicated, and cDNA was synthesized from mRNA using a RT reaction. Various target (wild-type) elastin cDNAs with unknown concentrations were competitively coamplified with known serial dilutions of the control mutant template, differing from the target cDNA by a short deletion. Gel fractions and computerized densitometry, were performed and cDNA concentration was calculated by linear regression.

RESULTS

The primers identified in our study (BOB-1 and BOB-2) accurately amplified a consistent length of the elastin cDNA, avoiding areas of alternative splicing. The average elastin mRNA concentration in BPH tissues was 53 attomole/mg +/- 11.6 vs. 140.6 attomole/mg +/- 19.6 in normal prostatic tissue (P = 0.019). The variation within every sample was less than 10%.

CONCLUSIONS

Our observations suggest a significant downregulation (70%) of the elastin mRNA gene in the transition zone of BPH patients.

Elastic system of the rat ventral prostate and its modifications following orchiectomy

BACKGROUND

The extracellular matrix (ECM) has important roles in prostatic development, and marked stromal changes take place in the rat ventral prostate (VP) after androgen deprivation. However, little knowledge exists about individual ECM components.

METHODS

The distribution of elastic fibers (EF) and elastic-related fibers (ERF) in the VP of castrated and control rats was investigated, using histochemistry and transmission electron microscopy (TEM).

RESULTS

EF are barely detected in the prostatic stroma, but ERF are relatively abundant. Castration results in a relative increase in the number and thickness of ERF. TEM showed an open network of ECM microfibrils throughout, the stroma and thin and short EF, which increase in number and thickness after orchiectomy.

CONCLUSIONS

The presence of elastic system components in the rat VP warrants the deformability required for the secretion exclusion under the action of smooth muscle cells, and the castration-induced modification may be related to the contraction of the tissue and maintenance of peculiar arrangements of other ECM components.

Collagen type VI is a component of the extracellular matrix microfibril network of the prostatic stroma

Stroma-epithelium relationships are of great relevance in prostatic morphogenesis and physiology. However, little knowledge exists about either stromal cells or extracellular matrix composition and arrangement in this system. Ultrastructural analysis revealed the existence of a microfibrillar system which occupies large areas of the rat prostatic stroma. In this work, we have applied immunocytochemistry and an ATP treatment for the ultrastructural identification of collagen type VI microfibrils, aiming at examining its participation in the prostatic microfibrillar network. Immunocytochemistry was also extended to a human case of prostatic nodular hyperplasia. Both methods succeeded in identifying collagen type VI in the rat ventral prostate. Collagen type VI is evenly distributed throughout the stroma but mainly associated with the basal lamina, collagen fibrils, and around the stromal cells. The use of ATP treatment allowed for the discrimination between collagen type VI and elastin-associated microfibrils, and demonstrated that these two classes of microfibrils establish an extended, mixed, and open network. The same aspects of association with the basal lamina, with stromal cells (particularly with smooth muscle cells), and with fibrillar components of the stroma were observed in the human tissue. We suggest that the collagen type VI and elastin-associated microfibril system may be involved in the control of some aspects of cellular behavior and may also play a structural role, maintaining the organ integrity after the deformations occurring under smooth muscle contraction.

Human prostatic smooth muscle cells in culture: estradiol enhances expression of smooth muscle cell-specific markers

Smooth muscle cells (SMCs) constitute a major cellular component of prostatic stroma. SMC tension plays an important role in urethral obstruction secondary to benign prostatic hyperplasia (BPH). We have developed an in vitro procedure for the propagation of human prostatic SMCs. Tissue specimens from patients undergoing radical prostatectomy or cystectomy were enzymatically disaggregated and cultured in MCDB-131 medium supplemented with horse serum, insulin, conditioned medium from the tumor cell line CRL-5813, and steroid hormones. The medium was assembled on the basis of the effects these supplements have on the growth of SMC cultures and on the expression of the two markers desmin and smooth muscle myosin. Addition of 0.1 microM of estradiol to the growth medium dramatically increased expression of these SMC-specific markers. Dihydrotestosterone (DHT) and hydrocortisone had a similar, albeit less pronounced effect. At three to five passages, about two thirds of the cells were immunohistologically positive for smooth muscle myosin or desmin. Almost all cells were positive for the myofibroblast marker smooth muscle alpha-actin throughout 10 passages and more. In SMC cultures, cells staining for smooth muscle myosin and desmin were found to seek direct contact to myofibroblasts. They grew in aggregates on a layer of myofibroblasts which adhered to the surface of the culture vessel. As revealed by transmission electron microscopy the cultured cells exhibited morphological features of myofibroblasts. Characteristics of smooth muscle cells, such as prominent bundles of microfilaments associated with dense bodies, basal laminae investing the cells, and numerous caveolae at the cell surfaces were regularly observed in cultures of low passages. After several passages, these features were markedly decreased and organelles of the biosynthetic system became more prominent. In summary, we present an in vitro model of prostatic SMCs and demonstrate that steroid hormones have characteristic effects on these cells. SMC cultures are expected to facilitate investigation of the functions and properties of human prostatic SMCs.

Effect of aromatase inhibitor, TZA-2209, on the prostate of androstenedione-treated castrated dogs: changes in prostate volume and histopathological findings

To determine whether the inhibition of estrogen-related effect in the prostate would be of value in the management of benign prostate hyperplasia (BPH), we examined the effect of TZA-2209, a new steroidal aromatase inhibitor, on the prostate in three of six castrated beagles that received 75 mg/week androstenedione. The three other animals served as controls. Sequential measurements of prostate volume by transrectal ultrasonography showed that the volume in TZA-treated dogs was significantly decreased compared with that in the controls. Prostatic aromatase activity was suppressed by TZA administration. Histopathologically, the stromal component was increased and glands were atrophied by androstenedione treatment. TZA administration increased the volume of the glands. Immunohistochemical detection of estramustine-binding protein showed more positive staining of the protein in the glands that were increased in volume by TZA administration. We concluded that the aromatase inhibitor effectively antagonized the estrogen-related stromal changes, however, this action was accompanied by stimulation of the glandular component due to the accumulation of androgens, the substrate of the aromatase. In the light of these findings, we suggest the simultaneous treatment for the androgen-glandular component route in the prostate is necessary for the effective management of BPH.

Prostatic ductal system in rats: regional variation in stromal organization

The rat prostate is composed of a complex system of branching ducts which terminate proximally at the urethra. It has been recognized that epithelial cells lining the ducts respond differently to androgen in various regions of the ducts, with responses ranging from proliferation to apoptosis, but the cellular mechanisms underlying these effects are unclear. Interaction between prostatic stroma and epithelium is essential to normal prostate growth and development, and the prostatic stroma is thought to be the first site of androgen action. Therefore we have examined the organization and distribution of stromal cell types along the rat prostatic ductal system. Using immunohistochemical techniques, we observed abundant fibrous tissue surrounding the distal region of the ducts, with a sparse, discontinuous smooth muscle layer. The intermediate region was surrounded by a continuous layers of smooth muscle one to two cells thick, which increased to greater than four layers thick at the proximal region. Fibrous tissue was located in interductal spaces and occasionally interspersed within the muscle layers in both regions. These observations indicate that regional variations in the distribution of stromal cell types exist and suggest that their corresponding secretory products could be responsible for the various effects of androgen on the epithelium in the rat prostatic ductal system.

Effects of hormones on the prostate in adult and aging men and animals

Literature on the effect of steroid hormones (androgens, estrogens, and other steroids), of peptide hormones (e.g., prolactin), and growth factors (e.g., EGF, FGF, TGF-beta), on the effect of castration and of experimental hormone application on the prostate is reviewed. Androgens have inductive, repressive, and interactive effects. They counterbalance an agonistic effect on proliferation and an antagonistic effect on cell death; they may influence DNA synthesis and induce the synthesis of substances with mitogenic effects on the prostate. Estrogens exert direct and indirect effects on the prostate. They suppress the secretion of gonatropins, thus repressing testicular androgen secretion. They stimulate the fibromuscular stroma and induce squamous metaplasia of the epithelium. Estrogens may also be involved in the onset of benign prostatic hyperplasia. Prolactin is preferentially bound in the diseased human prostate. An abundance of information has been gained on EGF, FGF, TGF-beta, and other growth factors. They may be involved in the development of prostatic hyperplasia. Castration leads to a striking reduction in prostatic size in a short period of time due to autophagic and heterophagic processes. In castrated individuals, the prostate is enriched in androgen-independent cells. Experimental hormone application involves the substitution of androgens as well as anti-androgens, long-term application of different hormones, and application of combinations of drugs. The results of several studies are described. Further directions in the field of prostate research should concentrate on the role of growth factors in prostate development and pathology and on the effect of certain lectins on prostate diseases. We think that the investigation of interactions between steroid hormones and growth factors in normal and pathological neovascularization of the prostate is important.

Hormonal regulation of nuclear type II estrogen binding sites in the dorsolateral prostate of noble rats

We previously demonstrated that simultaneous treatment of Noble (NBL) rats with estradiol (E2) and testosterone (T) for 16 weeks induces a proliferative response selectively in the dorsolateral prostates (DLP) of all treated animals [1, 2]. The unique sensitivity of rat DLP to the conjoint androgen-estrogen-induced mitogenic action may be attributable to the presence of a moderate affinity, high capacity, nuclear estrogen binder (type II sites) found exclusively in this prostatic lobe [2, 3]. Little is known about whether prostatic type II site levels are under hormonal regulation. The aim of this study is to determine whether testicular steroids play a role in regulating the basal and/or induced levels of type II site expression in rat DLP. In the first experiment, rats were castrated and immediately treated with 5 alpha-dihydrotestosterone (DHT) and/or E2 for 6 weeks to determine whether these steroids, separately or jointly, could sustain DLP type II site levels in castrates. Treatments of castrated rats with DHT and DHT+E2 were found to be effective in maintaining DLP type II site levels and gland wet weights at values close to those found in intact untreated controls, while treatments with E2 failed to maintain these parameters at levels observed in intact animals. In the second experiment, intact rats were treated with an androgen (T or DHT) or E2, alone or in combination, for 16 weeks to ascertain which hormonal regimen could induce a higher level of type II site expression in the DLP. Treatments of rats with an androgen (T or DHT) or E2 alone did not change DLP type II site levels even though T treatment caused a slight increase in gland weight, while E2 treatment induced prostatic atrophy. Contrary to single hormone treatments, combined T + E2 and DHT+E2 treatments were effective in inducing a doubling of type II sites and increases in wet weight of the DLPs. These data indicate that testicular androgen is the primary factor responsible for maintaining a basal level of type II site expression in rat DLP, while conjoint androgenic-estrogenic action is needed for the induction of a higher level of type II site expression in the tissue.