Cell type specific expression of steroid 5 alpha-reductase 2

The androgen receptor/filamin A complex as a target in prostate cancer microenvironment

Prostate cancer represents the major cause of cancer-related death in men and patients frequently develop drug-resistance and metastatic disease. Most studies focus on hormone-resistance mechanisms related to androgen receptor mutations or to the acquired property of prostate cancer cells to over-activate signaling pathways. Tumor microenvironment plays a critical role in prostate cancer progression. However, the mechanism involving androgen/androgen receptor signaling in cancer associated fibroblasts and consequences for prostate cancer progression still remains elusive. We now report that prostate cancer associated fibroblasts express a transcriptional-incompetent androgen receptor. Upon androgen challenging, the receptor co-localizes with the scaffold protein filamin A in the extra-nuclear compartment of fibroblasts, thus mediating their migration and invasiveness. Cancer-associated fibroblasts move towards epithelial prostate cancer cells in 2D and 3D cultures, thereby inducing an increase of the prostate cancer organoid size. Androgen enhances both these effects through androgen receptor/filamin A complex assembly in cancer-associated fibroblasts. An androgen receptor-derived stapled peptide, which disrupts the androgen receptor/filamin A complex assembly, abolishes the androgen-dependent migration and invasiveness of cancer associated fibroblasts. Notably, the peptide impairs the androgen-induced invasiveness of CAFs in 2D models and reduces the overall tumor area in androgen-treated 3D co-culture. The androgen receptor in association with β1 integrin and membrane type-matrix metalloproteinase 1 activates a protease cascade triggering extracellular matrix remodeling. The peptide also impairs the androgen activation of this cascade. This study offers a potential new marker, the androgen receptor/filamin A complex, and a new therapeutic approach targeting intracellular pathways activated by the androgen/androgen receptor axis in prostate cancer-associated fibroblasts. Such a strategy, alone or in combination with conventional therapies, may allow a more efficient treatment of prostate cancer.

Generation and Regulation of Spontaneous Contractions in the Prostate

Spontaneous myogenic contractions have been shown to be significantly upregulated in prostate tissue collected from men with Benign Prostatic Hyperplasia (BPH), an extremely common disorder of the ageing male. Although originally thought likely to be involved in 'housekeeping' functions, mixing prostatic secretions to prevent stagnation, these spontaneous myogenic contractions provide a novel opportunity to understand and treat BPH. This treatment potential differs from previous models, which focused exclusively on attenuating nerve-mediated neurogenic contractions. Previous studies in the rodent prostate have provided an insight into the mechanisms underlying the regulation of myogenic contractions. 'Prostatic Interstitial Cells' (PICs) within the prostate appear to generate pacemaker potentials, which arise from the summation of number of spontaneous transient depolarisations triggered by the spontaneous release of Ca²⁺ from internal stores and the opening of Ca²⁺-activated Cl^- channels. Pacemaker potentials then conduct into neighbouring smooth muscle cells to generate spontaneous slow waves. These slow waves trigger the firing of 'spike-like' action potentials, Ca²⁺ entry and contraction, which are not attenuated by blockers of neurotransmission. However, these spontaneous prostatic contractions can be modulated by the autonomic nervous system. Here, we discuss the mechanisms underlying rodent and human prostate myogenic contractions and the actions of existing and novel pharmacotherapies for the treatment of BPH. Understanding the generation of human prostatic smooth muscle tone will confirm the mechanism of action of existing drugs, inform the identification and effectiveness of new pharmacotherapies, as well as predict patient outcomes.

Subcellular localization of the five members of the human steroid 5α-reductase family

In humans the steroid 5α-reductase (SRD5A) family comprises five integral membrane enzymes that carry out reduction of a double bond in lipidic substrates: Δ⁴-3-keto steroids, polyprenol and trans-enoyl CoA. The best-characterized reaction is the conversion of testosterone into the more potent dihydrotestosterone carried out by SRD5A1-2. Some controversy exists on their possible nuclear or endoplasmic reticulum localization.

We report the cloning and transient expression in HeLa cells of the five members of the human steroid 5α-reductase family as both N- and C-terminus green fluorescent protein tagged protein constructs. Following the intrinsic fluorescence of the tag, we have determined that the subcellular localization of these enzymes is in the endoplasmic reticulum, upon expression in HeLa cells. The presence of the tag at either end of the polypeptide chain can affect protein expression and, in the case of trans enoyl-CoA reductase, it induces the formation of protein aggregates.

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All members of human testosterone 5α-reductase family were expressed in HeLa cells.

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Subcellular localization of SRD5A proteins in the endoplasmic reticulum is reported.

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The effect of GFP tagging at N- or C-term on SRD5A proteins expression was assessed.

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The TECRL gene is expressed for the first time and its product localizes in the ER.

5α-Reductases and Their Inhibitors

5α reductase is a key enzyme in androgen metabolism. Altered enzyme function and/or regulation is responsible for numerous human pathologies such as benign prostatic hyperplasia, acne, hirsutism and male pattern baldness. In order to block androgen action through inhibition of this enzyme, numerous compounds have been synthesized during the past two decades. Among them, 4-azasteroids and in particular finasteride have been extensively studied and used in the treatment of human diseases.

Anti-proliferation effects of Cistanches salsa on the progression of benign prostatic hyperplasia

Cistanche salsa has been used in traditional medicine for the treatment of kidney deficiency, neurasthenia, sexual dysfunction diseases, and benign prostatic hyperplasia (BPH). The aim of this study was to investigate the mechanism by which C. salsa extract (CSE) elicits an anti-proliferative effect on the prostate tissue of BPH-induced rats. The effects of CSE on BPH were evaluated in terms of prostate weight, production of serum dihydrotestosterone (DHT), and the mRNA expression of 5α-reductase type 1 and type 2 in the prostate tissue of BPH-induced rats. In addition, hematoxylin and eosin (H&E) staining was performed for histological examination of prostate gland morphology, and protein expression levels in prostate tissue were investigated by western blot analysis. CSE treatment decreased prostate weight, serum DHT concentration, and the mRNA expression of 5α-reductase type 1 and type 2 in prostate tissue of BPH-induced rats. In addition, CSE treatment suppressed cell proliferation by regulating the expression levels of inflammatory-related proteins (inducible nitric oxide synthase and cyclooxygenase 2) and apoptosis-associated proteins (caspase-3 and Bcl-2 family proteins). CSE may be a potential therapeutic candidate for BPH owing to its ability to regulate the expression of inflammatory and apoptosis-related proteins.

Androgens and prostate disease

A growing body of literature has established the anabolic benefi ts of testosterone (T) therapy in hypogonadal men. However, there remains a paucity of data regarding the risks of exogenous androgen use in older men and the potential for adverse effects on the prostate gland. Whether T therapy in older, hypogonadal men might worsen lower urinary tract symptoms or exacerbate, unmask, or even incite prostate cancer development has tempered enthusiasm for T therapy, while known prostatic disease has served as a relative contraindication to T therapy. Androgens are necessary for the development and maintenance of the prostate gland. However, epidemiologic studies do not consistently fi nd a positive relationship between endogenous serum androgen concentrations and the risk of prostate disease. Recent data demonstrate that 5α-reductase inhibitors decrease the risk of low-grade prostate cancer, suggesting that modifying androgen metabolism may have beneficial effects on prostate health, yet similar reductions in high-grade disease have not been observed, thereby questioning the true clinical benefits of these agents for chemoprevention. Knowing how to best investigate the relationship between androgens and the development of prostate disease given the lack of large, randomized trials is difficult. Accumulating data challenges the assumption that alterations in serum androgens have parallel effects within the prostate hormonal environment or change androgen-regulated processes within the gland. Long-term intervention studies are needed to truly ascertain the effects of androgen manipulation on prostate tissue and disease risk. However, available data do not support the notion that restoring serum androgens to normal physiologic ranges drives prostate disease.

Prostate epithelial AR inactivation leads to increased intraprostatic androgen synthesis

BACKGROUND

Regulation of steroid synthesis within the prostate is not well understood. In this study, we examined androgen synthesis and metabolism in the mouse prostate.

METHODS

Using LC-MSMS steroid assays, immunohistochemistry and real-time PCR we examined the role of prostate epithelial AR in regulating 5αR expression and subsequent androgen metabolism by analyzing natural differences in epithelial AR expression between lobes as well as in the prostate epithelial AR knockout (PEARKO) mouse model. Subsequently, the role of intraprostatic androgen metabolism and epithelial AR in the generation and progression of prostate epithelial pathology was examined using long-term exogenous testosterone (T) + estradiol (E2) exposure.

RESULTS

Epithelial AR and 5αR2 expression as well as intraprostatic DHT followed the same lobe-specific pattern being lower in anterior than the other lobes (n = 6-8, P < 0.05). Lobe-specific 5αR2 expression was similar in PEARKO and wild-type (WT) prostate. However, PEARKO prostate had higher intraprostatic DHT content with significantly increased 5αR2 expression localized in abnormal epithelium. T + E2 treatment induced epithelial pathology was more common in PEARKO prostate compared to WT (20% vs. 2%), and was associated with increased 5αR2 expression (n = 6, P < 0.001).

CONCLUSIONS

We suggest that androgen synthesis via 5αR2 expression is driven by its own product (DHT) acting on adjacent stromal cells in a paracrine loop leading to increased in situ androgen levels in the PEARKO prostate. This may form part of a feed-forward loop that promotes the development of epithelial pathology.

Regional distribution of 5α-reductase type 2 in the adult rat brain: an immunohistochemical analysis

The enzyme 5α-reductase (5αR) catalyzes the conversion of testosterone and other Δ(4)-3-ketosteroids into their 5α-reduced metabolites. Of the five members of the 5αR family, the type 2 enzyme (5αR2) plays a key role in androgen metabolism, and is abundantly distributed in the urogenital system. Although 5αR2 has been reported to be highly expressed in the brain during early developmental stages, little is currently known on its anatomical and cellular distribution in the adult brain. Thus, the present study was designed to determine the detailed localization of 5αR2 in the adult rat brain, using a highly specific polyclonal antibody against this isoform. Parasagittal and coronal sections revealed 5αR2 immunoreactivity throughout most brain regions, with strong immunolabeling in the layers III and VI of the prefrontal and somatosensory cortex, olfactory bulb, thalamic nuclei, CA3 field of hippocampus, basolateral amygdala and Purkinje cell layer of cerebellum. Lower 5αR2 levels were detected in the hypothalamus and midbrain. Moreover, double labeling fluorescence with confocal laser scanning microscopy (CLSM) revealed that 5αR2 is localized in neurons, but not in glial cells. Specifically, the enzyme was documented in the pyramidal neurons of the cortex by CLSM analysis of simultaneous Golgi-Cox and immunofluorescent staining. Finally, low levels of 5αR2 expression were identified in GABAergic cells across the cortex, hippocampus and striatum. These findings show that, in the adult brain, 5αR2 is distributed in critical regions for behavioral regulation, suggesting that the functional role of this isoform is present throughout the entire lifespan of the individual.

Estrogen and androgen signaling in the pathogenesis of BPH

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

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

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

Oxytocin increases 5alpha-reductase activity of human prostate epithelial cells, but not stromal cells

BACKGROUND

Oxytocin is known to modulate 5-alpha-reductase expression and has, therefore, been implicated in the etiology and novel pharmacological treatments of benign prostatic hyperplasia (BPH). These suggestions have been made in the absence of any direct evidence that oxytocin regulates expression or activity of 5-alpha-reductase isoenzymes in the human prostate. This study evaluated the effects of oxytocin on the activity and expression of 5-alpha-reductase isoenzymes I and II of human prostate stromal (PrSC; primary site of BPH development) and epithelial (PrEC) cells.

METHODS

Cell cultures were incubated with oxytocin, or oxytocin plus a specific oxytocin antagonist for 24 hr, and conversion of (3)H-Testosterone to dihydrotestosterone used to estimate total 5-alpha-reductase activity and to determine activity of both type I and type II isoenzymes. Fully quantitative real-time RT-PCR determined levels of expression of both isoenzymes following treatments.

RESULTS

Oxytocin significantly increased the total 5-alpha-reductase activity of PrEC but not of PrSC. 5-alpha-Reductase I gene expression and enzyme activity were also increased (P<0.05) in PrEC by oxytocin. Oxytocin significantly increased type II activity, but not expression, in PrEC. Oxytocin did not significantly affect 5-alpha-reductase activity or expression in PrSC.

CONCLUSION

Both 5-alpha-reductase I and II are expressed in normal human prostate stromal and epithelial cells. Only 5-alpha-reductase isoenzymes of prostate epithelium are modulated by oxytocin.

[Benign prostatic hyperplasia: a highly prevalent disease in the elderly]

The present review aims to provide an overview of benign prostatic hyperplasia (BPH), which has a remarkably high prevalence. The various theories of the aetiology of the disease are discussed, with special emphasis on those that concern the influence of growth factors. Questions related to the physiopathology of BPH are briefly summarized, since many symptoms apparently related to the disease may be caused by ageing or by interacting factors other than prostatism. The most common clinical manifestations, with symptoms divided into irritative and obstructive, as well as the currently available diagnostic procedures, are described. Finally, the therapeutic options are discussed, with special reference to KTP and Holmiun laser, which will drastically change treatment in the future.

Hormonal implications in the development and treatment of prostate cancer

In this article, the conflicting data concerning the androgen axis and prostate cancer development are reviewed in addition to how this pathway may be exploited to prevent the development of prostate cancer. The expanding role of hormone ablative therapy alone or in conjunction with standard therapies, the controversies of timing of therapy, and the completeness of ablation and its use on an intermittent basis are reviewed.

Age-Related Structural and Metabolic Changes in the Pelvic Reproductive End Organs

In this work, we provide preliminary data and a review of the literature regarding normal structural and functional changes that occur in the aging uterus, ovary, testicle, and prostate gland. It is expected that such knowledge will help physicians to distinguish physiologic changes from pathologic changes at an early stage. We retrospectively reviewed pelvic magnetic resonance imaging (MRI) scans of 131 female and 79 male subjects ages 13 to 86 years to determine changes in volume of the uterus, ovary, and prostate gland with age. Scrotal ultrasound examinations of 150 male subjects ages 0 to 96 years also were analyzed retrospectively to determine changes in testicular volume with age. In addition, (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) scans of 145 male subjects ages 11 to 90 years were analyzed retrospectively to assess for changes in maximum standardized uptake value (SUV(max)) of the testicles with age. The uterus had a mean volume of 38.55 +/- 3.68 cm(3) at 17 to 19 years of age, increased to a peak volume of 71.76 +/- 19.81 cm(3) between 35 to 40 years, and then declined to 24.02 +/- 8.11 cm(3) by the eighth decade of life. The maximal ovarian volume per subject maintained a relatively stable size in early life, measuring 9.46 +/- 3.25 cm(3) during the second decade of life, 8.46 +/- 3.32 cm(3) in the mid-fourth decade of life, and 7.46 +/- 3.33 cm(3) at 45 years of age, after which it declined to 4.44 +/- 2.02 cm(3) by the late fifth decade of life. The ovaries were not identifiable on MRI in subjects beyond the sixth decade of life. The volume of the prostate increased from 23.45 +/- 6.20 cm(3) during the second decade of life to 47.5 +/- 41.59 cm(3) by the late eighth decade of life; the central gland of the prostate increased from 9.96 +/- 3.99 cm(3) to 29.49 +/- 28.88 cm(3) during the same age range. Mean testicular volume was 11.2 +/- 5.9 cm(3). Testicular volume increased with age from birth to 25 years. After age 25, there was a significant decline in the testicular volume. The mean SUV(max) for the testicles was 1.9 +/- 0.5. Testicular metabolic activity demonstrated an increasing trend until the age of 35 years. A plateau in SUV(max) was observed after the age of 35 years until the age of 65 years. A slight decrease in SUV(max) was observed after the age of 65 years. The pelvic structures of men and women change both structurally and functionally over the lifespan, and such changes can be quantified using ultrasound, MRI, and (18)F-FDG-PET.

Finasteride to evaluate the efficacy of dutasteride in the management of patients with lower urinary tract symptoms and enlarged prostate

Patients with lower urinary tract symptoms and enlarged prostate were randomized to receive, in a double blind fashion, either Finasteride 5 mg/day or Dutasteride 0.5 mg/day for a period of 12 weeks. IPSS score, Qmax, and Quality of Life were assessed at the end of 0 and 12 week periods. Dutasteride significantly improved Qmax, reduced IPSS score, and improved Quality of Life as compared to Finasteride at the end of the 12-week period. Dutasteride with its inhibitory effects on type 1 and 2 5alpha-reductase, produces significantly better results than Finasteride.

Oxytocin and the human prostate in health and disease

Oxytocin is a peptide hormone produced by the neurohypophysis. The discovery that the peptide is produced locally within the male and female reproductive tracts has raised the possibility that oxytocin may have paracrine and autocrine actions outside of the nervous system. Oxytocin and its receptor have been identified in the human prostate. The prostate is an androgen-dependent organ whose function is to secrete components of the seminal fluid. Oxytocin has been shown to modulate contractility of prostate tissue and also to regulate local concentrations of the biologically active androgens. Oxytocin has also been shown to regulate cell growth. Prostate disease is common and results from abnormal growth of the gland. Oxytocin concentrations are altered in both benign and malignant prostate diseases and in vitro studies suggest that the peptide may be involved in the pathophysiology of these diseases.

Finasteride induced depression: a prospective study

Background

Finasteride is a competitive inhibitor of 5 alpha-reductase enzyme, and is used for treatment of benign prostatic hyperplasia and androgenetic alopecia. Animal studies have shown that finasteride might induce behavioral changes. Additionally, some cases of finasteride-induced depression have been reported in humans. The purpose of this study was to examine whether depressive symptoms or anxiety might be induced by finasteride administration.

Methods

One hundred and twenty eight men with androgenetic alopecia, who were prescribed finasteride (1 mg/day) were enrolled in this study. Information on depressed mood and anxiety was obtained by Beck Depression Inventory (BDI), and Hospital Anxiety and Depression Scale (HADS). Participants completed BDI and HADS questionnaires before beginning the treatment and also two months after it.

Results

Mean age of the subjects was 25.8(± 4.4) years. At baseline, mean BDI and HADS depression scores were 12.11(± 7.50) and 4.04(± 2.51), respectively. Finasteride treatment increased both BDI (p < 0.001) and HADS depression scores significantly (p = 0.005). HADS anxiety scores were increased, but the difference was not significant (p = 0.061).

Conclusion

This preliminary study suggests that finasteride might induce depressive symptoms; therefore this medication should be prescribed cautiously for patients with high risk of depression. It seems that further studies would be necessary to determine behavioral effects of this medication in higher doses and in more susceptible patients.

Five-alpha-reductase expression in benign and malignant urothelium: Correlation with disease characteristics and outcome

OBJECTIVES

To evaluate 5-alpha-reductase (5alphaR) expression in benign and malignant urothelium and to assess the relationship between 5alphaR expression and tumor stage, tumor grade, and clinical outcome in patients with urothelial carcinoma/transitional cell carcinoma.

METHODS

We performed immunohistochemistry for 5alphaR on 53 urothelial specimens from 36 patients with transitional cell carcinoma treated at our institution between June 2002 and July 2003. For each tumor and the adjacent nontumor urothelium, a semiquantitative staining score was calculated. We used t tests and analysis of variance to compare the staining score across groups. Kaplan-Meier and logistic regression analyses were performed to assess the relationship between 5alphaR expression and clinical outcome.

RESULTS

5alphaR was expressed throughout the non-neoplastic urothelium. Nontumor urothelium had greater mean staining scores than did tumor specimens (160.1 versus 105.5, P <0.01). Low staining scores were associated with high grade (P <0.05), Stage pT3, pT4, and pTis (P <0.05), and disease progression (P <0.05). A staining score less than the median was a risk factor for progression (odds ratio 6.2, P <0.01) on univariate regression analysis. Patients with a staining score less than the median had a greater likelihood of disease progression (log-rank P <0.05) and cause-specific mortality (log-rank P <0.05).

CONCLUSIONS

We demonstrated 5alphaR expression in human urothelium and found that expression is decreased in transitional cell carcinoma in relation to tumor grade and stage. Decreased 5alphaR expression was associated with disease progression and cause-specific mortality.

Cloning and Characterization of the 5α-Reductase Type 2 Promoter in the Rat Epididymis1

Steroid 5alpha-reductase converts testosterone to the more potent androgen, dihydrotestosterone. The molecular mechanisms responsible for maintaining high concentrations of the 5alpha-reductase type 2 mRNA in the caput epididymidis and for regulating its region-specific expression are unknown. To gain insight into its transcriptional regulation, the cloning and characterization of the 5' upstream region of 5alpha-reductase type 2 were undertaken. Sequential deletion analysis was done to map the 2243-base pair (bp) cloned 5' upstream region, and the constructs were transfected into epididymal PC1 cells and prostatic PC3 cells. In both cell lines, regulatory elements and the minimal promoter were mapped to the 485-bp region upstream of the start codon. Primer extension and 5' RACE identified one transcriptional start site at 33-bp upstream of the start codon. Using electrophoretic mobility shift assay, a specific band was observed in the -68- to -32-bp region in the presence of nuclear extracts. Supershift and mutational studies confirmed the binding of SP1 and, to a lesser extent, SP3 to the two potential SP1 binding sites and the preference of these proteins to one binding site over the other. SP1 and SP3 were both predominantly immunolocalized to the principal cells of the epididymis and follow distinct distribution patterns in this tissue. These results provide a framework crucial in the further investigation of the transcriptional regulation of 5alpha-reductase type 2 in the rat epididymis.

Anatomical and cellular localization of neuroactive 5?/3?-reduced steroid-synthesizing enzymes in the spinal cord

The complementary activities of 5 alpha-reductase (5 alpha-R) and 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) are crucial for the synthesis of neuroactive 5 alpha/3 alpha-reduced steroids, such as 3 alpha-androstanediol, allopregnanolone, and tetrahydrodeoxycorticosterone, which control several important neurophysiological mechanisms through allosteric modulation of gamma-aminobutyric acid type A receptors. Immunocytochemical localization of 3 alpha-HSD in the central nervous system (CNS) has never been determined. The presence and activity of 5 alpha-R have been investigated in the CNS, but only the brain was considered; the spinal cord (SC) received little attention, although this structure is crucial for many sensorimotor activities. We have determined the first cellular distribution of 5 alpha-reductase type 1 (5 alpha-R1) and type 2 (5 alpha-R2) and 3 alpha-HSD immunoreactivities in adult rat SC. 5 alpha-R1 immunostaining was detected mainly in the white matter (Wm). In contrast, intense 5 alpha-R2 labeling was observed in dorsal (DH) and ventral horns of gray matter (Gm). 3 alpha-HSD immunoreactivity was largely distributed in the Wm and Gm, but the highest density was found in sensory areas of the DH. Double-labeling experiments combined with confocal analysis revealed that, in the Wm, 5 alpha-R1 was localized in glial cells, whereas 35% of 5 alpha-R2 and 3 alpha-HSD immunoreactivities were found in neurons. In the DH, 60% of 5 alpha-R2 immunostaining colocalized with oligodendrocyte, 25% with neuron, and 15% with astrocyte markers. Similarly, 45% of 3 alpha-HSD immunoreactivity was found in oligodendrocytes, 35% in neurons, and 20% in astrocytes. These results are the first demonstrating that oligodendrocytes and neurons of the SC possess the key enzymatic complex for synthesizing potent neuroactive steroids that may control spinal sensorimotor processes.

Androgen-induced prostate-specific antigen gene expression is mediated via dihydrotestosterone in LNCaP cells

Prostate cancer is a leading cause of cancer death in American males. Androgens play an essential role in prostate development, growth and pathogenesis of benign prostate hyperplasia, and prostate cancer. Although testosterone is the main androgen secreted from the testes, dihydrotestosterone (DHT), a more potent androgen converted from testosterone by 5alpha-reductase isozymes, type 1 and 2, is the major androgen in the prostate cells. Thus, 5alpha-reductase(s) are critical in determining androgen activity in the prostate. However, it is unclear in prostate tumor cells whether 1 or 2 5alpha-reductase isozymes are expressed and whether they are functionally important. In the present report, we studied the importance of 5alpha-reductase isozymes in the androgen induction of prostate-specific antigen (PSA) gene expression in LNCaP prostatic tumor cells. Treatment with either testosterone or DHT in LNCaP cells produced dose- and time-dependent increases in PSA levels in the cell media and in PSA messenger RNA (mRNA) levels in the cells. However, testosterone-induced but not DHT-induced PSA gene expression was significantly inhibited by finasteride, a 5alpha-reductase inhibitor, in a dose-dependent manner. Furthermore, we demonstrated for the first time that both 5alpha-reductase-1 and 5alpha-reductase-2 mRNAs were expressed in LNCaP cells using reverse transcriptase-polymerase chain reaction (RT-PCR) and RT-PCR Southern blot analysis. These results suggest that both 5alpha-reductase isozymes are present and functionally important in prostatic tumor LNCaP cells and that DHT is a major mediator of androgen induction of PSA gene expression in these cells.

Changes in 5alpha-pregnane steroids and neurosteroidogenic enzyme expression in the perinatal sheep

Pregnane steroids have sedative and neuroprotective effects on the brain as a result of interactions with the steroid-binding site of the GABAA receptor. To determine whether the fetal brain is able to synthesize pregnane steroids de novo from cholesterol, we measured the expression of cytochrome P450 side-chain cleavage (P450scc) and 5alpha-reductase type II (5alphaRII) enzymes in fetal sheep from 72 to 144 d gestation (term approximately 147 d) and in newborn lambs at 3 and 19-26 d of age. Both P450scc and 5alphaRII expression was detectable by 90 d gestation in the major regions of the brain and also in the adrenal glands. Expression increased with advancing gestation and was either maintained at fetal levels or increased further after birth. In contrast, the relatively high content (200-400 pmol/g) of allopregnanolone (5alpha-pregnan-3alpha-ol-20-one), a major sedative 5alpha-pregnane steroid, present throughout the brain from 90 d gestation to term, was reduced significantly (<50 pmol/g) immediately after birth. These results suggest that although the perinatal brain has the enzymes potentially to synthesize pregnane steroids de novo from cholesterol, either the placenta is a major source of these steroids to the brain or other factors associated with intrauterine life may be responsible for high levels of allopregnanolone production in the fetal brain until birth.

Androgens and male physiology the syndrome of 5alpha-reductase-2 deficiency

Dihydrotestosterone (DHT), a potent androgen, is converted from testosterone by 5alpha-reductase isozymes. There are two 5alpha-reductase isozymes, type 1 and type 2 in humans and animals. These two isozymes have differential biochemical and molecular features. Mutations in type 2 isozyme cause male pseudohermaphroditism, and many mutations have been reported from various ethnic groups. The affected 46XY individuals have high normal to elevated plasma testosterone levels with decreased DHT levels and elevated testosterone/DHT ratios. They have ambiguous external genitalia at birth so that they are believed to be girls and are often raised as such. However, Wolffian differentiation occurs normally and they have epididymides, vas deferens and seminal vesicles. Virilization occurs at puberty frequently with a gender role change. The prostate in adulthood is small and rudimentary, and facial and body hair is absent or decreased. Balding has not been reported. Spermatogenesis is normal if the testes are descended. The clinical, biochemical and molecular genetic analyses of 5alpha-reductase-2 deficiency highlight the significance of DHT in male sexual differentiation and male pathophysiology.

Expression of androgen receptor and 5alpha-reductases in the human normal endometrium and its disorders

Androgen metabolism and actions are considered to play a very important role in the development and progression of the normal human endometrium and its disorders. Details regarding androgen actions in these tissues, however, have not been well studied. We first immunolocalized the androgen receptor (AR) and 5alpha-reductases, which catalyze the conversion of testosterone to the bioactive and potent androgen, 5alpha-dihydrotestesterone (DHT), in 18 normal cycling human endometria, 27 endometrial hyperplasia and 46 endometrioid endometrial adenocarcinomas. We also examined the mRNA expression of AR and 5alpha-reductases in 7 cases of endometrioid endometrial adenocarcinomas using reverse transcription polymerase chain reaction (RT-PCR). In the normal human endometrium, AR was immunolocalized predominantly in stromal cells of the proliferative phase of the menstrual cycle and in epithelial cells of the secretory phase, whereas 5alpha-reductase types 1 and 2 immunoreactivities were detected in the cytoplasm of epithelial cells but not in stromal cells throughout all phases of the menstrual cycle. In endometrial hyperplasia, the median labeling index (LI) for AR was 48.1%, whereas positive immunostaining for 5alpha-reductase Type 1 and Type 2 was detected in only 1 case. In endometrial carcinoma, AR immunoreactivity was detected in the nuclei of carcinoma cells and the number of positive cases was 39/44 (88.6%). Median LI for AR was 36.1%. Immunoreactivity for 5alpha-reductase Type 1 and Type 2 was detected in the cytoplasm of carcinoma cells and the number of positive cases was 37/44 cases (84.1%) and 34/44 (77.3%) for 5alpha-reductase Types 1 and 2, respectively. A significant positive correlation was detected between 5alpha-reductase Type 1 and Type 2 immunoreactivity (p < 0.001). AR LI was not correlated with the presence or absence of Type 1 and Type 2 5alpha-reductases. Results from our RT-PCR studies were consistent with those of immunohistochemistry. These results suggest that DHT may play more important roles than testosterone in the regulation of androgen action in endometrial cancer and normal human endometrium, especially in the secretory phase, in which both AR and 5alpha-reductase are increased. Androgenic actions may be also regulated predominantly by serum testosterone and not by DHT in endometrial hyperplasia because of the absence of 5alpha-reductases in the site of its actions.

Type-1 steroid 5 alpha-reductase is functionally active in the hair follicle as evidenced by new selective inhibitors of either type-1 or type-2 human steroid 5 alpha-reductase

Steroid 5 alpha-reductase catalyzes the reduction of testosterone (T) into the very potent androgen dihydrotestosterone (DHT). The different tissue expression patterns of the two isoforms of 5 alpha-reductase, namely type-1 and type-2 5 alpha-reductase (5 alpha-R1 and 5 alpha-R2, respectively), have prompted studies directed towards the synthesis of selective 5 alpha-R1 or 5 alpha-R2 inhibitors. In this present work, we have performed a structure/activity study on the inhibitory potential of indole carboxylic acids against hair follicle 5 alpha-reductase activity. We have demonstrated that this class of molecules were potent inhibitors of either 5 alpha-R1 or 5 alpha-R2 or both depending on (i) substituents in positions 4, 5 or 6 and (ii) the presence of a free carboxylic group. We have also found that only 5 alpha-R1 or 5 alpha-R1/R2 inhibitors were able to inhibit 5 alpha-reductase activity in plucked hairs from female volunteers or in freshly isolated female hair follicles, selective 5 alpha-R2 inhibitors being inactive.

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

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

Expression of 5alpha-reductases in human epithelial ovarian cancer: its correlation with androgen receptor status

Androgen metabolism and possible actions are considered to play some roles in human epithelial ovarian neoplasms, but the details have not been well studied. We have examined the expression of 5alpha-reductase type 1 and type 2, which catalyze the conversion of testosterone to more active androgen, 5alpha-dehydrotestosterone, and androgen receptor (AR), using immunohistochemistry (104 cases) and reverse transcription-polymerase chain reaction (RT-PCR) (16 cases) as a first step toward understanding the metabolism and possible actions of androgens in human common epithelial ovarian carcinoma. 5alpha-Reductase type 1 was immunopositive in 75 / 104 cases (72.0%), and 5alpha-reductase type 2 in 52 / 104 cases (50.0%) (P < 0.001). There was no significant correlation between patterns of immunolocalization and clinicopathological parameters examined. Median labeling index (LI) for AR was 17.8% (range 0 - 84.4%) which was significantly higher in serous carcinoma than other histological types (P < 0.001). There was a significant positive correlation between 5alpha-reductase type 1 immunoreactivity and AR LI (P = 0.0027), but no significant correlation was detected in 5alpha-reductase type 2. Results of RT-PCR analysis were also consistent with those of immunohistochemistry. The relatively wide distribution of 5alpha-reductase type 1, and its correlation to AR status in human epithelial ovarian malignancies suggest that this isozyme plays important roles in androgen metabolism and actions in these tumors.

Sexual function in patients with benign prostatic hyperplasia

Sexual health has significant impact on quality of life among men with benign prostatic hyperplasia (BPH). The degree of sexual dysfunction matches the severity of lower urinary tract symptoms (LUTS). Treatment of BPH affects not only LUTS, but sexual function as well. Medical, surgical, and minimally invasive therapies differ in their effect on erectile function, ejaculation, and sexual satisfaction. Choice of treatment modality takes into account baseline sexual function and patient expectations. This review outlines the relationship between LUTS and sexual function and how they change with the currently available treatments.

Localization of p450scc and 5alpha-reductase type-2 in the cerebellum of fetal and newborn sheep

Prenatally, neuroactive steroids that modulate GABAergic activity may be synthesized de novo within the fetal brain. We have examined changes in immunoreactivity staining for the steroidogenic enzymes cholesterol P450 side-chain cleavage (P450scc), and 5alpha-reductase type-2 in the cerebellum of late gestation (130-145 days gestation) fetal sheep and newborn lambs (1-4 weeks of age). Both enzymes were predominantly localized in the Purkinje cell body and dendrites of the fetal and newborn cerebellum, with weaker immunoreactivity in a few cells of the inner granular layer. P450scc immunoreactivity was present in Purkinje neurons expressing either of the neuronal microtubule associated proteins MAP1b/5 or MAP2a/b, but was absent from GFAP and HNK-1 positive cells. Soma of Purkinje neurons were also immunopositive for 5alpha-reductase type-2 in the fetuses, but expression decreased to just detectable levels in the 1-2 and 2-4 week old lambs. Both MAP1b/5- and MAP2a/b-positive Purkinje neurons showed 5alpha-reductase type-2 expression in the fetus, whereas the residual 5alpha-reductase staining in the newborn lamb was present only in MAP2a/b-positive Purkinje neurons. Allopregnanolone in the cerebellum decreased from 21.8+/-1.9 ng/g wet weight in fetuses at 140-145 days gestation to 6.7+/-0.5 ng/g in 2-4 week old lambs (P<0. 05). Thus, synthesis of neuroactive steroids from cholesterol is possible in cerebellar neurons in late gestation and persists into neonatal life, 5alpha-reductase type-2 expression is greater in the fetus compared to the neonate, and allopregnanolone concentrations in the cerebellum decrease significantly after birth.

Kinetic analysis of LY320236: competitive inhibitor of type I and non-competitive inhibitor of type II human steroid 5alpha-reductase

Type I and type II steroid 5alpha-reductases (5alpha-R) catalyze the conversion of testosterone (T) to dihydrotestosterone (DHT). LY320236 is a benzoquinolinone (BQ) that inhibits 5alpha-R activity in human scalp skin (Ki(typeI)=28.7+/-1.87 nM) and prostatic homogenates (Ki(typeII)=10.6+/-4.5 nM). Lineweaver-Burk, Dixon, and non-linear analysis methods were used to evaluate the kinetics of 5alpha-R inhibition by LY320236. Non-linear modeling of experimental data evaluated V(max) in the presence or absence of LY320236. Experimental data modeled to the following equation 1v=+ fixing the In0c value equal to 1.0 or 0 are consistent with non-competitive or competitive inhibition, respectively. LY320236 is a competitive inhibitor of type I 5alpha-R (In0c=0, Ki=3.39+/-0.38, RMSE = 1.300) and a non-competitive inhibitor of type II 5alpha-R (In0c=1, Ki=29. 7+/-3.4, RMSE = 0.0592). These data are in agreement with linear transformation of the data using Lineweaver-Burk and Dixon analyses. These enzyme kinetic data support the contention that the BQ LY320236 is a potent dual inhibitor with differing modes of activity against the two known human 5alpha-reductase isozymes. LY320236 represents a class of non-steroidal 5alpha-R inhibitors with potential therapeutic utility in treating a variety of androgen dependent disorders.

5alpha-reductase type 2 mutations are present in some boys with isolated hypospadias

PURPOSE

We determined whether 5a-reductase type 2 mutations are present in boys with isolated hypospadias.

MATERIALS AND METHODS

Penile skin tissues obtained at surgery during hypospadias repair were examined for 5alpha-reductase type 2 mutations by single strand conformational polymorphism and deoxyribonucleic acid sequence analysis. Clinical data, including family history of hypospadias and preoperative position of the urethral meatus, were correlated with the genetic findings.

RESULTS

Of the 81 specimens examined 7 (8.6%) involved a mutation in at least 1, 5alpha-reductase type 2 gene, while 2 patients had mutations in both alleles. The mutations identified were A49T, L113V and H231R. The A49T mutation in 5 patients was the most common (71%) and it was generally present in less severe forms of hypospadias. To our knowledge neither the A49T nor the L113V mutation has been previously reported in association with 5alpha-reductase type 2 deficiency and to date they have only been identified in cases of isolated hypospadias. Family history was negative in the 7 patients with 5a-reductase type 2 mutations but positive in 5 without mutations.

CONCLUSIONS

Some boys with isolated hypospadias have a mutation in at least 1 gene for 5alpha-reductase type 2. This finding suggests that a partial deficiency of 5alpha-reductase activity and inadequate levels of dihydrotestosterone in the fetal urethra may be sufficient to cause the phenotype of hypospadias without other clinical features of 5alpha-reductase deficiency. Family history may not be reliable for determining which boys with hypospadias are likely to have such mutations.

5alpha-reductase type 2 mutations are present in some boys with isolated hypospadias

PURPOSE

We determined whether 5a-reductase type 2 mutations are present in boys with isolated hypospadias.

MATERIALS AND METHODS

Penile skin tissues obtained at surgery during hypospadias repair were examined for 5alpha-reductase type 2 mutations by single strand conformational polymorphism and deoxyribonucleic acid sequence analysis. Clinical data, including family history of hypospadias and preoperative position of the urethral meatus, were correlated with the genetic findings.

RESULTS

Of the 81 specimens examined 7 (8.6%) involved a mutation in at least 1, 5alpha-reductase type 2 gene, while 2 patients had mutations in both alleles. The mutations identified were A49T, L113V and H231R. The A49T mutation in 5 patients was the most common (71%) and it was generally present in less severe forms of hypospadias. To our knowledge neither the A49T nor the L113V mutation has been previously reported in association with 5alpha-reductase type 2 deficiency and to date they have only been identified in cases of isolated hypospadias. Family history was negative in the 7 patients with 5a-reductase type 2 mutations but positive in 5 without mutations.

CONCLUSIONS

Some boys with isolated hypospadias have a mutation in at least 1 gene for 5alpha-reductase type 2. This finding suggests that a partial deficiency of 5alpha-reductase activity and inadequate levels of dihydrotestosterone in the fetal urethra may be sufficient to cause the phenotype of hypospadias without other clinical features of 5alpha-reductase deficiency. Family history may not be reliable for determining which boys with hypospadias are likely to have such mutations.

Gene expression in the epididymis

The epididymis is a tubular organ exhibiting vectorial functions of sperm concentration, maturation, transport, and storage. The molecular basis for these functions is poorly understood. However, it has become increasingly clear that regional differences along the length of the duct play a role in epididymal physiology and that region-specific gene expression is involved in the formation of these differences. Although not an overtly segmented organ, the epididymis consists of a series of highly coiled "zones," separated by connective tissue septulae and distinct by cell morphology and their pattern of gene expression. Thus, it constitutes an interesting mammalian model to study how pattern formation is achieved by differential gene activity. A large number of epididymis-expressed genes have been cloned and analyzed at the molecular level, most of them have been characterized by a distinct temporal and spatial expression pattern within the organ. Only recently have theories been developed about how and when during ontogenesis this pattern formation takes place and what its significance might be. This review summarizes the current knowledge on regionalized gene expression in the epididymis and presents hypotheses concerning its ontogenetic origin and regulation in the adult.

Localization of type 5 17beta-hydroxysteroid dehydrogenase, 3beta-hydroxysteroid dehydrogenase, and androgen receptor in the human prostate by in situ hybridization and immunocytochemistry

An important source of androgens in the human prostate are those synthesized locally from the inactive adrenal precursor dehydroepiandrosterone (DHEA) and its sulfated derivative DHEA-S. Three beta-HSD (hydroxysteroid dehydrogenase) converts DHEA into androstenedione (4-dione), whereas type 5 17beta-HSD catalyzes the reduction of 4-dione into testosterone in the human prostate and other peripheral intracrine tissues. In the present study, we have used two complementary approaches, namely in situ hybridization and immunocytochemistry, to identify the cells that contain the type 5 17beta-HSD messenger RNA and enzyme in human benign prostatic hyperplasia (BPH). Localization of 3beta-HSD and of the androgen receptor (AR) was also investigated by immunostaining in the same tissue. To find out whether there are any differences between BPH and normal prostate tissue, the localization of type 5 17beta-HSD was reexamined by immunocytochemistry in the normal human prostate samples and also in normal prostate epithelial cell line (PrEC). The in situ hybridization results obtained with a tritiated uridine triphosphate (3H-UTP)-labeled type 5 17beta-HSD riboprobe are in agreement with the immunostaining data obtained with a specific antibody to the enzyme. The immunostaining results obtained from normal prostate tissue and BPH were found to be similar. Thus, in the glandular epithelium, basal cells highly express the messenger RNA and the enzyme, whereas luminal cells show a much lower and variable level of expression. In the stroma and walls of blood vessels, fibroblasts and the endothelial cells lining the blood vessels show positive staining. Similar results are observed when the cellular distribution of 3beta-HSD is investigated. AR immunoreactivity, however, shows a different distribution because, in the epithelium, most of the nuclei of basal cells are negative, whereas the majority of nuclei of the luminal cells show positive staining. A strong reaction for AR is also found in most stromal cell nuclei and in the nuclei of most endothelial cells, as well as in some other cells of the walls of blood vessels. In conclusion, human type 5 17beta-HSD, as well as 3beta-HSD, are highly expressed, not only in the basal epithelial cells and stromal fibroblasts but also in the endothelial cells and fibroblasts of the blood vessels. AR, on the other hand, is highly expressed in the luminal cells. The present data suggest that DHEA is transformed in the basal cells of the glandular epithelium into 4-dione by 3beta-HSD and then into testosterone by type 5 17beta-HSD, whereas dihydrotestosterone is synthesized in the luminal cells after diffusion of testosterone from the underlying layer of basal cells. The potential role of androgen formation and action in blood vessels is unknown and opens new avenues of investigation for a better understanding of the multiple roles of androgens.

Expression of androgen receptor and growth factors in premalignant lesions of the prostate

Analysis of growth factors and receptors in putative premalignant lesions of prostatic adenocarcinoma should aid our understanding of their growth pathways. Sixty prostatic TURP (transurethral resection of the prostate) specimens exhibiting atypical adenomatous hyperplasia (AAH) and/or prostatic intraepithelial neoplasia (PIN) lesions were assayed by immunohistochemistry for androgen receptor (AR), epidermal growth factor receptor (EGFR), c-erbB-2, transforming growth factor-alpha (TGF-alpha), vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), MIB-1, E-cadherin, and high molecular weight keratin. Expression of these factors in the lesions was compared with that in the co-existing benign prostatic hyperplasia (BPH) or prostatic adenocarcinoma. Strong AR nuclear staining was observed in the luminal cells, but not the basal cells, of BPH and PIN lesions and in all the carcinomas examined. A similar growth factor and receptor profile was demonstrated in the secretory epithelium of high-grade PIN and carcinoma with a tendency to higher expression of membranous EGFR and c-erbB-2 and cytoplasmic TGF-alpha, and lower levels of FGF-2 than in low-grade PIN or BPH glands. Also, increased rates of proliferation, as estimated by MIB-1 stained cells, were observed in high-grade PIN in comparison with low-grade PIN and BPH and were not confined to the basal layer. AAH lesions resembled neither BPH nor carcinoma. Proliferation was virtually absent (MIB-1 expression); both AR and E-cadherin expression was significantly reduced; and, with the exception of FGF-2, all the other growth factors and receptors studied were absent. The results presented would support a premalignant role for high-grade PIN, whilst AAH would appear to represent a quiescent phenotype unlikely to progress to neoplasia.

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

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

Regional distribution of 5alpha-reductase type 1 and type 2 mRNA along the human epididymis

OBJECTIVE

To determine the regional distribution and relative expression of 5alpha-reductase type 1 and type 2 mRNA within the human testis and regions of the epididymis.

DESIGN

Prospective observational study.

SETTING

University academic medical center.

PATIENT(S)

Two young adult male organ donors.

INTERVENTION(S)

None

MAIN OUTCOME MEASURE(S)

The distribution of 5alpha-reductase type 1 and type 2 mRNA in the testis and regions of the epididymis was detected by Northern blot analysis. The relative abundance of each 5alpha-reductase mRNA was evaluated using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in which cyclophilin mRNA, a house-keeping gene product, was coamplified as the reference standard.

RESULT(S)

Northern blot analysis revealed the 5alpha-reductase type 2 transcript in the midcaput, distal caput, corpus, and proximal cauda of the epididymis, but the transcript was undetectable in the testis, proximal caput, and distal cauda region. No transcript for the type 1 isozyme was detected by Northern blot. The more sensitive RT-PCR showed low levels of type 1 mRNA in the testis and epididymis, with the highest abundance in the proximal caput. Type 2 mRNA of 5alpha-reductase was most abundant in the midcaput, was decreased in the more distal regions, and was more abundant than type 1 mRNA in all epididymal regions except for the proximal caput.

CONCLUSION(S)

Both 5alpha-reductase type 1 and type 2 mRNAs are present in the human epididymis. The type 2 isozyme mRNA is predominant, being more highly expressed than the low-abundance type 1 mRNA.

5alpha-reductase and 17beta-hydroxysteroid dehydrogenase expression in epithelial cells from hyperplastic and malignant human prostate

The aim of this study on testosterone (T) metabolism in benign prostatic hyperplasia (BPH) and prostatic cancer was to compare the formation of metabolites in freshly isolated epithelial cells and in cells of long-term cultures (2 passages) and to identify the 5alpha-reductase (5alpha-R) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) isoforms responsible for metabolite formation. Androst-4-enedione (A), dihydrotestosterone (DHT) and 5alpha-androstanedione (5alpha-A) formation were measured by high-performance liquid chromatography coupled to a Flo-one HP radioactivity detector. Enzyme isoforms were studied by Northern blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR). T conversion into A by 17beta-HSD, rather than reduction into DHT by 5alpha-R, was by far the predominant activity in cultured epithelial cells. The metabolic profile did not differ substantially between BPH and cancer cells. Long-term cell culture led to an increase in A formation compared with the level recorded in freshly isolated cells, with no significant incidence on the relative DHT level. According to RT-PCR results, both 5alpha-R isoforms (1 and 2) and 2 17beta-HSD isoforms (2 and 3) are present in epithelial cell cultures and in tissues. According to Northern blot analyses, the mRNAs for 5alpha-R2 and 17beta-HSD4 are expressed in tissue and those for 5alpha-R1 and types 2 and 4 17beta-HSD in isolated cell cultures. Moreover, finasteride, a specific 5alpha-R2 inhibitor, inhibits DHT and 5alpha-A formation in long-term cell culture of adenocarcinoma epithelial cells plated on Matrigel, suggesting a 5alpha-R2 expression. Thus, although 5alpha-R2 is present in freshly isolated epithelial cell cultures and in long-term epithelial cells cultured on Matrigel and predominates in prostate tissue, it is the 5alpha-R1 isoform that is preferentially expressed in epithelial cell cultures.

Steroid 5alpha-reductase inhibitors in androgen-dependent disorders

Inhibition of the steroid 5alpha-reductases shows promise in the treatment of a number of androgen-dependent disorders, such as benign prostatic hyperplasia, male pattern baldness, and acne. The design of potent and isozyme-selective inhibitors has provided biologists and clinicians with important tools for elucidating complex androgen physiology, and has already resulted in the development of one marketed drug.

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

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