Qualitative and quantitative evaluation of prostatic histomorphology in rats following chronic treatment with finasteride, a 5-alpha reductase inhibitor

Effect of finasteride particle size reduction on its pharmacokinetic, tissue distribution and cellular permeation

Finasteride (FSD), a specific competitive inhibitor of the steroid type-II 5α-reductase enzyme, is used in treatment of benign prostate hyperplasia (BPH) and male pattern baldness. The drug is of limited solubility that affect its dissolution and bioavailability. The aim was to study the effect of FSD particle size reduction on the pharmacokinetic, tissue distribution and cellular permeation. An optimized drug micro- and nano-particles were developed, characterized, administered to group of rats, and systemic pharmacokinetic and tissue distribution within target and not-target organs were determined using near-infrared (NIR) spectroscopy technique. Moreover, the cellular permeation of the prepared formulations through normal prostate epithelial cells was assessed and compared to pure FSD. The developed micro- and nano-particles were of 930 and 645 nm, respectively. Plasma maximum drug levels (C_max) and overall exposure (AUC) of both formulations were not significantly higher than unformulated drug. However, micronized FSD achieved significant higher concentration within the target tissue (prostate) within the current study compared to pure drug and nano-sized formulation as well. Yet, this is explained by the higher sequestration ability of spleen tissue to the nano-sized formula compared to micro-sized FSD. At the cellular level, permeation of nano-sized FSD through prostate epithelial cells was superior to the unformulated FSD as well as the micro-sized drug formulation. FSD particle size reduction significantly influences its cellular permeation and to a lesser extend affect its systemic pharmacokinetics and tissue distribution after oral administration.

Do 5α-Reductase Inhibitors Raise Circulating Serum Testosterone Levels? A Comprehensive Review and Meta-Analysis to Explaining Paradoxical Results

INTRODUCTION

Many studies have reported that 5α-reductase inhibitors (finasteride and dutasteride) raise serum testosterone (T) levels, yet there is lack of consistency among studies on this point.

AIM

To review and meta-analyze available studies reporting changes in serum T concentrations in men treated with 5α-reductase inhibitors (5α-RIs).

METHODS

A Medline search using PubMed and EMBASE was performed including the following key words: "finasteride," "dutasteride," "testosterone and 5α-reductases."

MAIN OUTCOME MEASURE

Relevant studies were extracted, evaluated, and analyzed. Of these, 40 studies were analyzed qualitatively and 11 were included in the meta-analysis. A random effects model was used to conduct the meta-analysis.

RESULTS

In 11 studies comprising 1,784 patients with age ranging between 18 and 83 years and average treatment follow-up of 17 months, meta-analytic estimate of the mean baseline change was 27 (95% confidence interval 1-54). The meta-analysis did not demonstrate unequivocal significant increase in serum T levels. The increase was not uniform among all studies reported. Sensitivity analysis showed that no single study contributed decisively to the outcome or could be attributed to drug action. The reported increases in T levels with finasteride or dutasteride in men with low baseline serum T may be attributed, in part, to increased trapping of T by unsaturated sex hormone binding globulin (SHBG) due to dissociation of 5α-dihydrotestosterone. In men with high baseline T levels, there appears to be no change in serum T levels. 10 studies reported luteinizing hormone, follicle-stimulating hormone, SHBG, and estradiol values and none reported significant changes in their levels, suggesting that observed changes in serum T levels are unlikely mediated by gonadotropins levels or peripheral conversion of T to estradiol.

CONCLUSION

5α-RI therapy is not associated with consistent and significant increases in serum T levels. Traish AM, Krakowsky Y, Doros G, et al. Do 5α-reductase inhibitors raise circulating serum testosterone levels? A comprehensive review and meta-analysis to explaining paradoxical results. Sex Med Rev 2019;7:95-114.

Fibrillar collagen genes are not coordinately upregulated with TGF β1 expression in finasteride-treated prostate

Benign prostatic hyperplasia (BPH) is the most common cause of lower urinary tract symptoms (LUTS) in older men. In this regard, recent studies have attempted to define the relationships between prostatic fibrosis, LUTS, and increased expression of transforming growth factor β1 (TGF β1) in BHP. Therapeutic approaches for BPH such as 5-α-reductase inhibitors and alpha-adrenergic blocking agents increase TGF β1 expression in the prostatic tissue. Here, we investigated the effects of the 5-α-reductase inhibitor-finasteride-on rat ventral prostate tissue, especially with regard to the tissue distribution and gene expression of fibrillar collagens. Adult Wistar rats (n = 15) were treated with finasteride (25 mg/kg/day) by subcutaneous injection for 7 and 30 days. Age-matched, vehicle-treated (n = 15) adult Wistar rats were used as control. Finasteride treatment reduced prostate size and increased the area of types I and III collagen fibers in the prostatic stroma. As expected, TGF β1 mRNA expression was upregulated by finasteride treatment. However, COL1A1 and COL3A1 mRNA expressions decreased after both 7 and 30 days of finasteride treatment, suggesting that finasteride treatment promotes prostate parenchyma and stroma changes, which lead to the observed types I and III collagen remodeling without de novo collagen synthesis. The upregulation of TGF β1 mRNA and protein associated with the 5-α-reductase inhibitor is more closely related to epithelial and stromal cell death pathways than to prostatic fibrosis.

Preparation of finasteride capsules-loaded drug nanoparticles: formulation, optimization, in vitro, and pharmacokinetic evaluation

In this study, optimized freeze-dried finasteride nanoparticles (NPs) were prepared from drug nanosuspension formulation that was developed using the bottom–up technique. The effects of four formulation and processing variables that affect the particle size and solubility enhancement of the NPs were explored using the response surface optimization design. The optimized formulation was morphologically characterized using transmission electron microscopy (TEM). Physicochemical interaction among the studied components was investigated. Crystalline change was investigated using X-ray powder diffraction (XRPD). Crystal growth of the freeze-dried NPs was compared to the corresponding aqueous drug nanosuspension. Freeze-dried NPs formulation was subsequently loaded into hard gelatin capsules that were examined for in vitro dissolution and pharmacokinetic behavior. Results revealed that in most of the studied variables, some of the quadratic and interaction effects had a significant effect on the studied responses. TEM image illustrated homogeneity and shape of the prepared NPs. No interaction among components was noticed. XRPD confirmed crystalline state change in the optimized NPs. An enhancement in the dissolution rate of more than 2.5 times from capsules filled with optimum drug NPs, when compared to capsules filled with pure drug, was obtained. Crystal growth, due to Ostwald ripening phenomenon and positive Gibbs free energy, was reduced following lyophilization of the nanosuspension formulation. Pharmacokinetic parameters from drug NPs were superior to that of pure drug and drug microparticles. In conclusion, freeze-dried NPs based on drug nanosuspension formulation is a successful technique in enhancing stability, solubility, and in vitro dissolution of poorly water-soluble drugs with possible impact on the drug bioavailability.

O impacto na expressão agnors e apoptose na próstata do hamster-mesocricetus auratus (HMA) submetido à aplicação de finasterida

OBJETIVO: Avaliar o impacto na expressão AgNORs e apoptose na próstata do hamster-Mesocricetus auratus (hMa) submetido à aplicação de finasterida. MÉTODOS: Vinte roedores da espécie hMa (n=20), machos foram separados aleatoriamente em grupos de dez animais: grupo-Finasterida (n=10) e grupo-Controle (n=10). No grupo-finasterida foi administrado 7,14 ng/mL de finasterida, subcutâneo (SC), no dorso, três vezes por semana, por 90 dias. Foi avaliada a expressão AgNORs como marcador de proliferação celular e a apoptose como marcador de morte celular. RESULTADOS: A expressão de AgNORs foi menor no grupo-finasterida, 2,846±0,877 versus 3,68 ±1,07 grumos argilófilos por micrômetro ao quadrado (µm²) no grupo-controle, p= < 0,0001. A apoptose foi mais frequente no grupo-finasterida, 53,62±1,389 versus 14,76 ± 2,137 µm² no grupo-controle, p= 0,0408. CONCLUSÃO: Observou-se diminuição da expressão de AgNORs e promoção da apoptose na próstata dos roedores em estudo, que foram submetidos à aplicação de finasterida.

Protein Profiling of Rat Ventral Prostate following Chronic Finasteride Administration

To better understand the effects of antiandrogens on the prostate, we investigated the changes in the proteome of rat ventral prostate (VP) following treatment with a well characterized 5alpha-reductase inhibitor, finasteride. Sprague-Dawley rats were treated daily by gavage with finasteride at 0, 1, 5, 25, and 125 mg/kg/day. Changes in plasma hormone levels as well as the weight and histology of sex accessory tissues were determined after 28 days of treatment and showed a dose-related decrease of VP weights together with a marked atrophy of the tissue visible at the macroscopic and microscopic levels. In addition, significant reductions in seminal vesicle and epididymis weights were noted. VP proteins were analyzed by two-dimensional gel electrophoresis: 37 proteins, mainly involved in protein synthesis, processing, and cellular trafficking and in metabolism, detoxification, and oxidative stress, were identified as modulated by finasteride. The prominent feature of this study is the demonstration of finasteride dose-dependent up-regulation of a protein similar to l-amino-acid oxidase 1 (Lao1). An up-regulation of this protein was also observed with the antiandrogen flutamide. Lao1 expression occurred as early as 48 h after antiandrogen administration and persisted throughout the treatment duration. Immunohistochemistry showed that this protein was only detectable in epithelial cells and secretory vesicles. Altogether these data point to a potential use of Lao1 to reveal antiandrogen-induced prostate injury.

Effects of finasteride on the vascular surface density, number of microvessels and vascular endothelial growth factor expression of the rat prostate

INTRODUCTION

Finasteride is a 5-alpha-reductase inhibitor used in the medical treatment of benign prostatic hyperplasia (BPH) and appears to be effective in treating prostatic bleeding secondary to BPH. The exact mechanism of this effect is not known. The aim of this study was to evaluate the effects of finasteride on the vascular surface density (VSD), number of microvessels (NVES) and vascular endothelial growth factor (VEGF) expression of the rat prostate.

MATERIALS AND METHODS

Nineteen adult male rats were used. Finasteride was given to 14, and there were 5 in the control group. Finasteride 80 mg/kg was administered daily via orogastric tube as a suspension for three months. Rats were sacrificed and vascular structures of the prostates were labelled immunohistochemically using CD31 antibodies. VSD and NVES of the prostates were assessed by means of a peroxidase labeled streptavidin-biotin method. VEGF expression was examined by immunohistochemistry using VEGF monoclonal antibody.

RESULTS

Mean prostatic weights were decreased significantly in rats given finasteride (p=0.0001). Although an increase in VSD was detected in the finasteride group it was not significant (p=0.26). NVES was significantly increased in the finasteride group (p=0.033). No significant difference was detected between the two groups in terms of VEGF expression (p=0.48).

CONCLUSION

Finasteride does not seem to decrease VSD, NVES and VEGF expression at the level of the rat prostate. The effect of reduction of bleeding in BPH is likely to be due to its effect on shrinking glandular hyperplasia which might enhance vessel wall stability rather than decreasing overall vascularity.

Does Finasteride Alter the Pathology of the Prostate and Cancer Grading?

All forms of androgen-deprivation therapy, including finasteride, induce distinctive histologic changes in benign and neoplastic prostatic epithelial cells, including cytoplasmic clearing, nuclear and nucleolar shrinkage, and chromatin condensation. Treated cancer has a significantly higher architectural (Gleason) grade, lower nuclear grade, and smaller nucleolar diameter than untreated controls, creating the potential for grading bias. Recognition of these changes may be difficult in needle biopsies and lymph node metastases with treated cancer because of the subtle infiltrative pattern and inconspicuous nucleoli. The effects of finasteride may be less pronounced than other forms of therapy with variable distribution throughout the prostate; further, there may be greater sensitivity of low and intermediate-grade cancer than high-grade cancer. The Gleason grading system for cancer should not be used after finasteride treatment as it is not validated in this setting and is likely to overestimate the biologic potential of high-grade cancer observed after therapy. Chemoprevention trials with agents such as finasteride that alter morphology should not rely on cancer grading as a secondary endpoint owing to grading bias.

Genistein alters growth but is not toxic to the rat prostate

The mortality of clinical prostate cancer is lower in Asian populations than in American or European men. Asian men typically consume more soy than their Western counterparts, leading to the investigation of individual components, particularly phytoestrogens, as protective factors against prostate cancer. Genistein, the predominant isoflavone in soy, has been reported to reduce the incidence of prostate cancer in animal models, but the underlying biological action remains to be elucidated. The purpose of this investigation was to identify the effects of the phytoestrogen, genistein and the synthetic estrogen diethylstilbestrol (DES), as a control, on development and function of the rat dorsolateral prostate (DLP) when given in the diet. The effects of testosterone and dihydrotestosterone (DHT) injections were also tested. Analysis of individual lobes of the DLP revealed that 1000 mg/kg, but not 250 mg/kg, of a genistein AIN-76A diet slightly reduced lateral prostate type 1 (LP1) bud perimeter. However, expression of the secretory dorsal protein 1 (DP1) and 5alpha-reductase type II activity were not altered in the prostate. This suggested that prostate differentiation, and not toxicity, had occurred. DES in the diet reduced and testosterone injections elevated relative prostate weights and perimeters of the dorsal, LP1, lateral prostate type 2 and DP1 expression. DHT increased relative prostate weights but did not significantly increase individual lobe perimeter. Unlike DES, maximally tolerated doses of genistein in the diet were not toxic to the rat prostate.

[Effects of chronic alcohol drinking on rat's prostate. Experimental study]

OBJECTIVE

We have studies both the morphologic and morphometric modifications that the alcohol induces in subjected rats to chronic intake of alcohol and to evaluate the reversibility of this alterations after suppressing the ingesta of alcohol.

MATERIAL AND METHODS

The animals underwent diverse outlines of chronic intake of alcohol and diverse morphometric parameters of the prostate were valued at the level of optic microscopy.

RESULTS

Two morphologic prostatic patterns was observed according to the studied group of animals (experimental or control). It seems to be that the dose of alcohol was the factor that more it influenced in the morphometric variations of the cells.

Does long-term finasteride therapy affect the histologic features of benign prostatic tissue and prostate cancer on needle biopsy? PLESS Study Group. Proscar Long-Term Efficacy and Safety Study

OBJECTIVES

Finasteride, a common agent used to treat benign prostatic hyperplasia (BPH), inhibits 5-alpha-reductase. Testosterone is converted by 5-alpha-reductase to the more potent dihydrotestosterone, which is the primary androgen in the prostate. Leuprolide is a stronger antiandrogen that is used to downstage prostate cancer before radical prostatectomy. Leuprolide induces marked atrophy of prostate carcinoma cells, which sometimes makes pathologic diagnosis of cancer difficult, although evaluation at radical prostatectomy is easier than at biopsy. It is unknown whether finasteride produces similar changes, which would result in greater diagnostic difficulty because such changes would be seen on biopsy to rule out cancer in men with suspicious clinical findings treated for BPH. The current study investigated the histologic effects of finasteride therapy on human prostate cancer and benign prostatic tissue on needle biopsy.

METHODS

In blinded manner, we reviewed 53 needle biopsy specimens showing prostate carcinoma (35 treated with finasteride, 18 with placebo). Also reviewed in blinded manner were 50 benign needle biopsy specimens (25 treated with finasteride, 25 with placebo). The Gleason score, number of cores involved, percentage cancer involvement in a core, percentage of atrophic changes in cancer cells, presence of mitoses, blue-tinged mucinous secretions, prominent nucleoli, and high-grade prostatic intraepithelial neoplasia were documented for each case in the cancer group. The percentage of atrophy, basal cell hyperplasia, transitional metaplasia, chronic inflammation, and stromal proliferation was documented for each case in the benign group.

RESULTS

No significant histologic differences were present in either the benign or cancer group between cases treated with finasteride and placebo.

CONCLUSIONS

We conclude that finasteride treatment for BPH does not cause difficulty in the diagnosis of cancer in prostate needle specimens. It is possible that there are severely atrophic areas resulting from finasteride treatment that are undersampled. However, the conclusion that cancer seen on needle biopsy in men treated with finasteride is unaltered and readily identified as cancer remains valid.

Effects of long-term treatment with Serenoa repens (Permixon) on the concentrations and regional distribution of androgens and epidermal growth factor in benign prostatic hyperplasia

BACKGROUND

The n-hexane lipido-sterol extract of Serenoa repens (LSESr, Permixon, Pierre Fabre Medicament, Castres, France), a phytotherapeutic agent used in the treatment of benign prostatic hyperplasia (BPH), has a multisite mechanism of action including inhibition of types 1 and 2 5alpha-reductase and competitive binding to androgen receptors in prostatic cells. Here, the response of testosterone (T), dihydrotestosterone (DHT), and epidermal growth factor (EGF) in BPH tissue of patients treated with LSESr (320 mg/day for 3 months) is analyzed.

METHODS

BPH samples were sectioned in periurethral, subcapsular, and intermediate regions: in each region T, DHT, and EGF were determined by radioimmunoassay after purification on celite columns or Sep-pak C18 cartridges.

RESULTS

In the untreated group, T, DHT, and EGF presented the highest concentrations in the periurethral region (615 +/- 62 (SE) pg/g tissue, 7,317 +/- 551 pg/g tissue, and 20.9 +/- 3.3 ng/g tissue, respectively) with respect to the peripheral subcapsular region (425 +/- 45 pg/g tissue, 4,215 +/- 561 pg/g tissue, and 10.8 +/- 1.4 ng/g tissue, respectively). In the LSESr-treated group, a statistically significant reduction was observed, mainly in the periurethral region of DHT (2,363 +/- 553 pg/g tissue, P < 0.001) and EGF (6.98 +/- 2.48 ng/g tissue, P < 0.01), with increased T values (1,023 +/- 101 pg/g tissue, P < 0.001).

CONCLUSIONS

The decrease of DHT and the rise of T in BPH tissue of patients treated with Permixon confirms the capacity of this drug to inhibit in vivo 5alpha-reductase in human pathological prostate. A marked decrease of EGF, associated with DHT reduction, was also observed. These biochemical effects, similar to those obtained with finasteride, are particularly evident in the periurethral region, whose enlargement is responsible for urinary obstruction, with respect to the subcapsular region. A possible speculation is that the preferential reduction of DHT and EGF content in the periurethral region is involved in the clinical improvement of the obstructive symptoms in BPH during LSESr therapy.

Morphological and hormonal changes in the ventral and dorsolateral prostatic lobes of rats treated with finasteride, a 5-alpha reductase inhibitor

BACKGROUND

In rats, the prostate is divided into three distinct lobes, and the lobes are dependent on androgens [testosterone (T) and dihydrotestosterone (DHT)] as trophic hormones. However, the reasons for the difference in the incidence of proliferative changes reported are not well-understood. Administration of finasteride, a 5-alpha reductase (5alphaR) inhibitor which selectively inhibits the conversion of T to DHT, results in elevated intraprostatic T levels. However, long-term (2 years) administration of finasteride results in no increase in proliferative changes in the ventral lobes of the rat prostate. Therefore, studies were designed to determine the differences in intraprostatic hormonal levels, morphology, and 5alphaR activity in different lobes of the rat prostate.

METHODS

Sexually mature male Sprague-Dawley rats were used in all studies. Finasteride was administered orally to rats. The methodology included determination of intraprostatic T and DHT levels by radioimmunoassay, qualitative and quantitative evaluation of prostatic morphology, and in vitro determination of 5alphaR activities in rat prostatic lobes.

RESULTS

A significant amount of 5alphaR activity was observed in the dorsal, ventral, and lateral lobes of the rat prostate. Both 5alphaR isozymes (types 1 and 2) were present in all lobes, based on 5alphaR activities observed at both acidic and neutral pH. Oral administration of finasteride (160 mg/kg/day) for 15 days resulted in significant (P < or = 0.001) decreases in intraprostatic DHT levels and increases in T levels; when compared to controls, the mean decrease in DHT levels in the ventral and the dorsolateral lobes was 86% and 94%, respectively, and the mean increase in T levels in the ventral and the dorsolateral lobes was approximately 3 times and 20 times, respectively, higher than in controls. Chronic administration of finasteride (80 mg/kg/day) for 6 months resulted in significant (P < or = 0.001) decreases in the weights of the prostatic lobes, which correlated with significant (P < or = 0.001) decreases in the total number of epithelial and stromal cells per gland in both the ventral and dorsolateral lobes of the prostate. There were no qualitative differences in prostatic morphology between the control and finasteride-treated groups. A short-term study in control rats exposed to bromodeoxyuridine (Brdu) showed that the number of Brdu-labeled cells in the dorsolateral lobe was significantly (P < or = 0.05) greater than in the ventral lobe.

CONCLUSIONS

This first comparative study has highlighted some of the similarities and differences among the prostatic lobes of the rat. Inhibition of conversion of T to DHT with finasteride resulted in a significant increase in intraprostatic T levels and a significant decrease in DHT levels in rats; despite a significant increase in intraprostatic T levels, the prostate remained atrophic, indicating that DHT alone has a trophic effect on the prostate.

Role of finasteride in the treatment of recurrent hematuria secondary to benign prostatic hyperplasia

OBJECTIVES

We evaluated the efficacy of finasteride for the treatment of gross hematuria secondary to benign prostatic hyperplasia in a prospective fashion.

METHODS

Twelve patients with recurrent episodes of gross hematuria secondary to benign prostatic hyperplasia were treated with finasteride 5 mg/day. Before initiating treatment, we excluded other sources of hematuria using intravenous urography, cystoscopy, and urine culture.

RESULTS

Bleeding subsided within 2 weeks of treatment in all 12 patients. Minimum follow-up was 6 months. Finasteride was well tolerated by all 12 patients.

CONCLUSIONS

Finasteride appears to be effective in treating recurrent gross hematuria secondary to benign prostatic hyperplasia. This therapy should be considered an alternative to transurethral resection of the prostate or hormonal ablation in patients with recurrent hematuria and no significant obstructive uropathy or adenocarcinoma of the prostate.

Effects of finasteride, a type 2 5-alpha reductase inhibitor, on fetal development in the rhesus monkey (Macaca mulatta)

In genetic male fetuses, dihydrotestosterone (DHT) plays an important role in normal prostatic and external genital differentiation. The enzyme steroid 5-alpha reductase (5 alpha R) catalyzes the conversion of testosterone (T) to DHT. The importance of 5 alpha R in sexual differentiation is evident from the study of human genetic males who congenitally lack this enzyme and consequently develop ambiguous genitalia. These individuals are specifically deficient in the type 2 isozyme, whereas the normal type 1 isozyme activity has been found. The purpose of this study was to determine 1) the suitability of the rhesus monkey for testing the safety of 5 alpha R inhibitors when administered during pregnancy and 2) the potential risk of administering a known type 2 5 alpha R inhibitor, finasteride, during the critical period of internal and external genital differentiation in rhesus monkeys. In vitro studies were also performed on selected rhesus monkey tissues to determine the distribution of the 5 alpha R isozymes. Gravid monkeys were treated once daily from gestational days (GD) 20 to 100. Sonographic monitoring was performed during the course of gestation to monitor viability, growth, and organ system development. Detailed fetal evaluations for developmental abnormalities were performed at term (GD 152 +/- 2). A group of 13 pregnant monkeys ("positive control") were given a high oral dose (2 mg/kg/day) of finasteride to demonstrate that inhibiting type 2 5 alpha R results in specific external genital abnormalities in male fetuses. Thirty-two pregnant monkeys were administered an intravenous (i.v.) formulation of finasteride at doses of 8, 80, or 800 ng/day. The highest i.v. dose selected was at least 60-750 times the semen levels of finasteride in man given orally 5 or 1 mg/day, respectively. Seventeen vehicle-control pregnant monkeys were also included. Administration of a high oral dose (2 mg/kg/day) of finasteride resulted in external genital abnormalities characterized by hypospadias, preputial adhesions to the glans, a small underdeveloped scrotum, a small penis, and a prominent midline raphe in male fetuses; however, no developmental abnormalities were seen in female fetuses. Similarly, no abnormalities were observed in either male or female fetuses of mothers given iv doses (8, 80, or 800 ng/day) of finasteride during pregnancy. The in utero sonographic findings in fetuses correlated with the gross findings at term. These studies have shown that external genital abnormalities can be produced in male monkey fetuses when exposed to a high oral dose (2 mg/kg/day) of finasteride, whereas no abnormalities were observed in fetuses exposed to the i.v. formulation of finasteride. Detailed in vitro studies demonstrated that the rhesus monkey also has two 5 alpha R isozymes (types 1 and 2) with a tissue distribution similar to that seen in man and, furthermore, that finasteride is a potent, mechanism-based inhibitor with selectivity for both human and rhesus type 2 5 alpha R. These studies have demonstrated that the monkey is a suitable model for assessing the safety of 5 alpha R inhibitors administered during pregnancy.

Prostate pathology case study seminar

Great strides have been made in the past decade in our understanding of the pathology of the prostate. Diagnostic criteria have been proposed, debated, and refined for a number of entities, including prostatic intraepithelial neoplasia, atypical adenomatous hyperplasia, basal cell proliferations, postatrophic hyperplasia, verumontanum mucosal gland hyperplasia, and numerous new variants of prostatic adenocarcinoma such as ductal adenocarcinoma, mucinous carcinoma, signet ring cell carcinoma, and lymphoepithelioma-like carcinoma. This report presents a series of case studies in prostate pathology which illustrate some of the contemporary issues which confront the pathologist and urologist.

Influence of diethylstilbestrol, Leuprolelin (a luteinizing hormone-releasing hormone analog), Finasteride (a 5 alpha-reductase inhibitor), and castration on the lobar subdivisions of the rat prostate

The effects of various means of interfering with androgen action on rat coagulating gland, ventral prostate, lateral type 1 prostate, lateral type 2 prostate, and dorsal prostate were examined morphologically and quantitatively by assessing DNA content, wet weight, protein content, and zinc concentrations. Adult male Sprague-Dawley rats were subjected to 2 weeks of interfering with androgen action by treatment with Leuprolelin (a luteinizing hormone-releasing hormone analog), Finasteride (a 5 alpha-reductase inhibitor), or diethylstilbestrol (DES), or by physical castration. For all prostatic lobes, inhibition of 5 alpha-reductase elicited the smallest reduction in prostatic wet weight, DNA and protein contents, and zinc concentration. The most profound reductions in all parameters were elicited by castration. Treatments with DES and Leuprolelin gave intermediate effects with DES being the more effective in reducing all parameters in all prostatic lobes. Morphological changes elicited by all forms of androgen blockade were reduction of epithelial height, relative increase of connective tissue, reduction in ductal diameter, length, and number. The order of effectiveness of the various treatments on morphological features was as described above. While all forms of androgen blockade elicited similar effects throughout the prostate, differences in response to all forms of interference with androgen action were observed in different lobes of the prostate with regard to wet weight, DNA and protein contents, and zinc concentration as well as morphological effects. Regressive changes at the morphological level were particularly striking in the coagulating gland and ventral prostate, and indistinct in the lateral type 2 prostate. Prostatic zinc concentration in both normal and androgen-deprived rats was the highest in the lateral type 2 prostate and was reduced by interfering with androgen action to the greatest extent in the dorsolateral prostate (lateral type 1 and type 2, and dorsal prostate). The distribution of zinc correlated with the expression of metallothionein, which was detected by immunocytochemistry only in the lateral type 2 prostate of both normal and androgen deprived rats. Intraprostatic heterogeneity of zinc and metallothionein expression emphasizes interlobar differences in biological function within the rat prostate. The mechanism of development of regional heterogeneity within the prostate may shed light on the pathogenesis of prostatic proliferative diseases (prostatic hyperplasia and prostatic cancer) that initially owe their development to focal changes within large cell populations.

Treatment of benign prostatic hyperplasia with 5-alpha-reductase inhibitor: morphological changes in patients who fail to respond

AIMS

To describe the prostatic adenectomy specimens of six patients with symptomatic benign prostatic hyperplasia (BPH) who failed to respond to long term treatment with a 5-alpha-reductase inhibitor, finasteride.

METHODS

Histological sections from six cases of BPH who had been treated with finasteride were investigated. Five patients were prescribed 5 mg finasteride daily for six months and one patient 5 mg daily for 12 months. The patients underwent adenectomy as their urethral obstruction failed to resolve. Twenty cases of untreated BPH served as controls.

RESULTS

In patients taking finasteride for six months the prostatic adenectomy specimens showed a reduction in the size of the prostate and an increase in the stroma:epithelial and stroma:lumen ratios compared with controls. The size of the ducts and acini was not as uniform as in the controls. In particular, some ducts and acini were still lined by a bistratified epithelium similar to that found in controls but lacked undulations at the epithelial border; other ducts/acini were atrophic. Some scattered clusters of small acini with a focally fragmented basal cell layer were observed in two of the five treated cases. One prostatic adenectomy specimen, from the patient treated for one year, showed extensive lobular atrophy and diffuse squamous and transitional cell metaplasia. At the periphery of the transition zone, there was a complex intra-acinar papillary-cribriform proliferation of clear cells without nuclear atypia, similar to clear cell papillary hyperplasia. The periurethral region showed stromal nodules in both patients and controls.

CONCLUSIONS

Morphological evaluation of finasteride treated BPH showed changes in the lobules of the transition zone, but not in the periurethral stroma.

Current treatment of BPH

Benign prostatic hypertrophy (BPH) is one of the most common diseases of adult males which increases with age. Effective therapeutic agents are an attractive option for patients for whom surgery is not a necessity, improving quality of life when compared with watchful waiting. Epidemiological studies show that 88% of patients over 80 years of age present anatomical BPH. This prevalence is similar in male populations throughout the world. Surgical treatment (transurethral resection of the prostate: TURP) has been the gold standard for over 50 years in patients with an enlarged prostate and obstructive symptoms but 20% of patients remain unsatisfied with surgery. Various medicinal preparations have been used since biblical times, in particular plant extracts which are still prescribed in Europe. Some claim to have an enzymatic inhibitory effect, but currently have not demonstrated objective efficacy. Alpha-blockers act on bladder and prostate smooth muscle, the contraction of which is mediated through alpha 1-receptors. Treatment has shown increased uroflow, decreased residual volume and a decrease in symptoms of BPH. Alpha-blockers; however, have shown no effect on prostate volume nor a reduction in the need for surgery for these patients. Finasteride, currently the only 5 alpha-reductase inhibitor approved for treatment of symptomatic BPH, has been widely investigated. The drug has been shown to decrease prostate volume, improve symptoms, uroflow and invasive urodynamic parameters in the majority of patients. Dihydrotestosterone (DHT) is decreased but the level of serum testosterone is maintained. Prostatic specific antigen is decreased by 50% as an effect of the drug on epithelial cells. Overall, the drug is well tolerated but some patients have shown decreased libido and/or impotency; however, two-thirds of these patients improved when the treatment was continued. Two effective medical therapies are currently available for treating symptomatic BPH: finasteride and alpha antagonists. Studies are now in progress to determine whether a combination of these therapies would be an effective alternative to surgery or watchful waiting.