Structure of the human type II 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) gene: adrenal and gonadal specificity

History of Adrenal Research: From Ancient Anatomy to Contemporary Molecular Biology

The adrenal is a small, anatomically unimposing structure that escaped scientific notice until 1564 and whose existence was doubted by many until the 18th century. Adrenal functions were inferred from the adrenal insufficiency syndrome described by Addison and from the obesity and virilization that accompanied many adrenal malignancies, but early physiologists sometimes confused the roles of the cortex and medulla. Medullary epinephrine was the first hormone to be isolated (in 1901), and numerous cortical steroids were isolated between 1930 and 1949. The treatment of arthritis, Addison's disease, and congenital adrenal hyperplasia (CAH) with cortisone in the 1950s revolutionized clinical endocrinology and steroid research. Cases of CAH had been reported in the 19th century, but a defect in 21-hydroxylation in CAH was not identified until 1957. Other forms of CAH, including deficiencies of 3β-hydroxysteroid dehydrogenase, 11β-hydroxylase, and 17α-hydroxylase were defined hormonally in the 1960s. Cytochrome P450 enzymes were described in 1962-1964, and steroid 21-hydroxylation was the first biosynthetic activity associated with a P450. Understanding of the genetic and biochemical bases of these disorders advanced rapidly from 1984 to 2004. The cloning of genes for steroidogenic enzymes and related factors revealed many mutations causing known diseases and facilitated the discovery of new disorders. Genetics and cell biology have replaced steroid chemistry as the key disciplines for understanding and teaching steroidogenesis and its disorders.

Ellagic Acid Triggers the Necrosis of Differentiated Human Enterocytes Exposed to 3-Nitro-Tyrosine: An MS-Based Proteomic Study

To study the molecular basis of the toxicological effect of a dietary nitrosated amino acid, namely, 3-nitrotyrosine (3-NT), differentiated human enterocytes were exposed to dietary concentrations of this species (200 μM) and analyzed for flow cytometry, protein oxidation markers and MS-based proteomics. The possible protective role of a dietary phytochemical, ellagic acid (EA) (200 μM), was also tested. The results revealed that cell viability was significantly affected by exposure to 3-NT, with a concomitant significant increase in necrosis (p < 0.05). 3-NT affected several biological processes, such as histocompatibility complex class II (MHC class II), and pathways related to type 3 metabotropic glutamate receptors binding. Addition of EA to 3-NT-treated cells stimulated the toxicological effects of the latter by reducing the abundance of proteins involved in mitochondrial conformation. These results emphasize the impact of dietary nitrosated amino acids in intestinal cell physiology and warn about the potential negative effects of ellagic acid when combined with noxious metabolites.

Genetic Testing for a Patient with Suspected 3 Beta-Hydroxysteroid Dehydrogenase Deficiency: A Case of Unreported Genetic Variants

3beta-hydroxysteroid dehydrogenase type II deficiency (HSD3B2 deficiency), a rare form of congenital adrenal hyperplasia (CAH), is characterized by varying degrees of salt loss and incomplete masculinization in males and mild virilization or normal external genitalia in females. We report the case of a patient (46XY) showing salt loss and incomplete masculinization, markedly elevated levels of 17OHP (17 hydroxyprogesterone), ACTH (Adreno Cortico Tropic Hormone), testosterone and delta4androstenedione (delta4A), low levels of cortisol and absence of bone skeletal alterations that frequently characterize POR (Cytochrome P450 oxidoreductase) deficiency. Mutation analysis by Sanger sequencing of the HSD3B2 gene showed that the patient presented with a compound heterozygote for two novel variants c.370A>G p.Ser124Gly and c.308-6 G>A. The two HSD3B2 gene variants were also present in the patient’s older brother showing only incomplete masculinization. The in silico analysis revealed a probable damaging effect of c.370A>G p.Ser124Gly: residue p.Ser124 is highly conserved among species and seems to be located in the catalytic site of the enzyme, playing a pivotal role in NAD(H) binding to its substrate. Intronic c.308-6G>A variant is predicted to be likely pathogenic; the substitution seems to cause a change in the splice acceptor site located 6bp downstream of the variant. The two siblings seem to be affected by 3β-HSD2 deficiency; nevertheless, the two novel variants are likely to cause variable expressivity of the disease.

11-Oxygenated androgens in health and disease

The adrenal gland is a source of sex steroid precursors, and its activity is particularly relevant during fetal development and adrenarche. Following puberty, the synthesis of androgens by the adrenal gland has been considered of little physiologic importance. Dehydroepiandrosterone (DHEA) and its sulfate, DHEAS, are the major adrenal androgen precursors, but they are biologically inactive. The second most abundant unconjugated androgen produced by the human adrenals is 11β-hydroxyandrostenedione (11OHA4). 11-Ketotestosterone, a downstream metabolite of 11OHA4 (which is mostly produced in peripheral tissues), and its 5α-reduced product, 11-ketodihydrotestosterone, are bioactive androgens, with potencies equivalent to those of testosterone and dihydrotestosterone. These adrenal-derived androgens all share an oxygen atom on carbon 11, so we have collectively termed them 11-oxyandrogens. Over the past decade, these androgens have emerged as major components of several disorders of androgen excess, such as congenital adrenal hyperplasia, premature adrenarche and polycystic ovary syndrome, as well as in androgen-dependent tumours, such as castration-resistant prostate cancer. Moreover, in contrast to the more extensively studied, traditional androgens, circulating concentrations of 11-oxyandrogens do not demonstrate an age-dependent decline. This Review focuses on the rapidly expanding knowledge regarding the implications of 11-oxyandrogens in human physiology and disease.

Intracrinology-revisited and prostate cancer

The formation of steroid hormones in peripheral target tissues is referred to as their intracrine formation. This process occurs in hormone dependent malignancies such as prostate and breast cancer in which the disease can be either castrate resistant or occur post-menopausally, respectively. In these instances, the major precursor steroid of androgens and estrogens is dehydroepiandrosterone (DHEA) and DHEA-SO4. This article reviews the major pathways by which adrenal steroids are converted to the potent male sex hormones, testosterone (T) and 5α-dihydrotestosterone (5α-DHT) and the discrete enzyme isoforms involved in castration resistant prostate cancer. Previous studies have mainly utilized radiotracers to investigate these pathways but have not used prevailing concentrations of precursors found in castrate male human serum. In addition, the full power of stable-isotope dilution liquid chromatography tandem mass spectrometry has not been applied routinely. Furthermore, it is clear that adaptive responses occur in the transporters and enzyme isoforms involved in response to androgen deprivation therapy that need to be considered.

MECHANISMS IN ENDOCRINOLOGY: Rare defects in adrenal steroidogenesis

Congenital adrenal hyperplasia (CAH) is a group of genetic disorders of adrenal steroidogenesis that impair cortisol synthesis, with compensatory increases in ACTH leading to hyperplastic adrenals. The term 'CAH' is generally used to mean 'steroid 21-hydroxylase deficiency' (21OHD) as 21OHD accounts for about 95% of CAH in most populations; the incidences of the rare forms of CAH vary with ethnicity and geography. These forms of CAH are easily understood on the basis of the biochemistry of steroidogenesis. Defects in the steroidogenic acute regulatory protein, StAR, disrupt all steroidogenesis and are the second-most common form of CAH in Japan and Korea; very rare defects in the cholesterol side-chain cleavage enzyme, P450scc, are clinically indistinguishable from StAR defects. Defects in 3β-hydroxysteroid dehydrogenase, which also causes disordered sexual development, were once thought to be fairly common, but genetic analyses show that steroid measurements are generally unreliable for this disorder. Defects in 17-hydroxylase/17,20-lyase ablate synthesis of sex steroids and also cause mineralocorticoid hypertension; these are common in Brazil and in China. Isolated 17,20-lyase deficiency can be caused by rare mutations in at least three different proteins. P450 oxidoreductase (POR) is a co-factor used by 21-hydroxylase, 17-hydroxylase/17,20-lyase and aromatase; various POR defects, found in different populations, affect these enzymes differently. 11-Hydroxylase deficiency is the second-most common form of CAH in European populations but the retention of aldosterone synthesis distinguishes it from 21OHD. Aldosterone synthase deficiency is a rare salt-losing disorder. Mild, 'non-classic' defects in all of these factors have been described. Both the severe and non-classic disorders can be treated if recognized.

The Genetic and Environmental Factors Underlying Hypospadias

Hypospadias results from a failure of urethral closure in the male phallus and affects 1 in 200-300 boys. It is thought to be due to a combination of genetic and environmental factors. The development of the penis progresses in 2 stages: an initial hormone-independent phase and a secondary hormone-dependent phase. Here, we review the molecular pathways that contribute to each of these stages, drawing on studies from both human and mouse models. Hypospadias can occur when normal development of the phallus is disrupted, and we provide evidence that mutations in genes underlying this developmental process are causative. Finally, we discuss the environmental factors that may contribute to hypospadias and their potential immediate and transgenerational epigenetic impacts.

Adrenal androgens and androgen precursors-definition, synthesis, regulation and physiologic actions

The human adrenal produces more 19 carbon (C19) steroids, by mass, than either glucocorticoids or mineralocorticoids. However, the mechanisms regulating adrenal C19 steroid biosynthesis continue to represent one of the most intriguing mysteries of endocrine physiology. This review will discuss the C19 steroids synthesized by the human adrenal and the features within the adrenal that allow production of these steroids. Finally, we consider the effects of these steroids in normal physiology and disorders of adrenal C19 steroid excess.

3?-hydroxysteroid dehydrogenase type II deficiency on newborn screening test

3b-hydroxysteroid dehydrogenase II (3β-HSD) deficiency represents a rare CAH variant. Newborns affected with its classic form have salt wasting in early infancy and genital ambiguity in both sexes. High levels of 17-hydroxypregnenolone (Δ517OHP) are characteristic, but extra-adrenal conversion to 17-hydroxyprogesterone (17OHP) may lead to positive results on newborn screening tests. Filter paper 17OHP on newborn screening test was performed by immunofluorometric assay, and serum determinations of 17OHP and Δ517OHP, by radioimmunoassay. A 46,XY infant with genital ambiguity and adrenal crisis at three months of age presented a positive result on newborn screening for CAH. Serum determinations of 17OHP and Δ517OHP were elevated, and a high Δ517OHP/cortisol relation was compatible with the diagnosis of 3β-HSD deficiency. Molecular analysis of the HSD3B2 gene from the affected case revealed the presence of the homozygous p.P222Q mutation, whereas his parents were heterozygous for it. We present the first report of 3β-HSD type II deficiency genotype-proven detected at the Newborn Screening Program in Brazil. The case described herein corroborates the strong genotype-phenotype correlation associated with the HSD3B2 p.P222Q mutation, which leads to a classic salt-wasting 3β-HSD deficiency. Further evaluation of 17OHP assays used in newborn screening tests would aid in determining their reproducibility, as well as the potential significance of moderately elevated 17OHP levels as an early indicator to the diagnosis of other forms of classic CAH, beyond 21-hydroxylase deficiency.

Differential regulation of human 3β-hydroxysteroid dehydrogenase type 2 for steroid hormone biosynthesis by starvation and cyclic AMP stimulation: studies in the human adrenal NCI-H295R cell model

Human steroid biosynthesis depends on a specifically regulated cascade of enzymes including 3β-hydroxysteroid dehydrogenases (HSD3Bs). Type 2 HSD3B catalyzes the conversion of pregnenolone, 17α-hydroxypregnenolone and dehydroepiandrosterone to progesterone, 17α-hydroxyprogesterone and androstenedione in the human adrenal cortex and the gonads but the exact regulation of this enzyme is unknown. Therefore, specific downregulation of HSD3B2 at adrenarche around age 6–8 years and characteristic upregulation of HSD3B2 in the ovaries of women suffering from the polycystic ovary syndrome remain unexplained prompting us to study the regulation of HSD3B2 in adrenal NCI-H295R cells. Our studies confirm that the HSD3B2 promoter is regulated by transcription factors GATA, Nur77 and SF1/LRH1 in concert and that the NBRE/Nur77 site is crucial for hormonal stimulation with cAMP. In fact, these three transcription factors together were able to transactivate the HSD3B2 promoter in placental JEG3 cells which normally do not express HSD3B2. By contrast, epigenetic mechanisms such as methylation and acetylation seem not involved in controlling HSD3B2 expression. Cyclic AMP was found to exert differential effects on HSD3B2 when comparing short (acute) versus long-term (chronic) stimulation. Short cAMP stimulation inhibited HSD3B2 activity directly possibly due to regulation at co-factor or substrate level or posttranslational modification of the protein. Long cAMP stimulation attenuated HSD3B2 inhibition and increased HSD3B2 expression through transcriptional regulation. Although PKA and MAPK pathways are obvious candidates for possibly transmitting the cAMP signal to HSD3B2, our studies using PKA and MEK1/2 inhibitors revealed no such downstream signaling of cAMP. However, both signaling pathways were clearly regulating HSD3B2 expression.

In silico structural, functional and pathogenicity evaluation of a novel mutation: an overview of HSD3B2 gene mutations

Mutations of 3 beta hydroxysteroid dehydrogenase type II (HSD3B2) gene result in different clinical consequences. We explain a patient who demonstrated a salt wasting form of 3βHSD deficiency in infancy. Signs of hyponatremia and hyperkalemia were recognized in the infant with ambiguous genitalia and perineal hypospadias. The 46,XY male was genotyped by direct sequencing of HSD3B2 gene. Steroid profiles showed elevated concentration of 17 hydroxyprogesterone, and decrease in concentration of cortisol, and testosterone. Dehydroepiandrotone (DHEA) to androstenedione ratio had 6 fold increases. Direct sequencing of the patient revealed homozygous missense A82P mutation in exon 3. This mutation was confirmed by segregation analysis of the parents. Bioinformatic tools were used for in silico structural and functional analyses. Also, the pathological effect of the mutation was validated by different software. Alanine is a conserved amino acid in the membrane binding domain of the enzyme and proline substitution was predicted to destabilize the protein. This report may highlight the importance of the screening programs of the disorder in Iran.

Human hydroxysteroid dehydrogenases and pre-receptor regulation: insights into inhibitor design and evaluation

Hydroxysteroid dehydrogenases (HSDs) represent a major class of NAD(P)(H) dependent steroid hormone oxidoreductases involved in the pre-receptor regulation of hormone action. This is achieved by HSDs working in pairs so that they can interconvert ketosteroids with hydroxysteroids resulting in a change in ligand potency for nuclear receptors. HSDs belong to two protein superfamilies the aldo-keto reductases and the short-chain dehydrogenase/reductases. In humans, many of the important enzymes have been thoroughly characterized including the elucidation of their three-dimensional structures. Because these enzymes play fundamental roles in steroid hormone action they can be considered to be drug targets for a variety of steroid driven diseases, e.g. metabolic syndrome and obesity, inflammation, and hormone dependent malignancies of the endometrium, prostate and breast. This article will review how fundamental knowledge of these enzymes can be exploited in the development of isoform specific HSD inhibitors from both protein superfamilies. Article from the Special issue on Targeted Inhibitors.

Structural aspects of the p.P222Q homozygous mutation of HSD3B2 gene in a patient with congenital adrenal hyperplasia

Type II 3β-hydroxysteroid dehydrogenase/Δ5-Δ4-isomerase (3β-HSD2), encoded by the HSD3B2 gene, is a key enzyme involved in the biosynthesis of all the classes of steroid hormones. Deleterious mutations in the HSD3B2 gene cause the classical deficiency of 3β-HSD2, which is a rare autosomal recessive disease that leads to congenital adrenal hyperplasia (CAH). CAH is the most frequent cause of ambiguous genitalia and adrenal insufficiency in newborn infants with variable degrees of salt losing. Here we report the molecular and structural analysis of the HSD3B2 gene in a 46,XY child, who was born from consanguineous parents, and presented with ambiguous genitalia and salt losing. The patient carries a homozygous nucleotide c.665C>A change in exon 4 that putatively substitutes the proline at codon 222 for glutamine. Molecular homology modeling of normal and mutant 3β-HSD2 enzymes emphasizes codon 222 as an important residue for the folding pattern of the enzyme and validates a suitable model for analysis of new mutations.

The intracrine sex steroid biosynthesis pathways

There is an increasing number of differences reported between the steroidogenesis pathways described in the traditional literature related to gonadal steroidogenesis and the more recent observations achieved using new technologies, especially molecular cloning, pangenomic expression studies, precise quantification of mRNA expression using real-time PCR, use of steroidogenic enzymes stably transfected in cells, detailed enzymatic activity analysis in cultured cell lines and mass spectrometry analysis of steroids. The objective of this chapter is to present steroidogenesis in the light of new findings that demonstrate pathways of biosynthesis of estradiol (E(2)) and dihydrotestosterone (DHT) from adrenal dehydroepiandrosterone (DHEA) in peripheral intracrine tissues which do not involve testosterone as intermediate as classically found in the testis and ovary. Steroidogenic enzymes different from those of the ovary and testis act in a tissue-specific manner to catalyze the transformation of DHEA into active sex steroids. These new pathways are especially important in post-menopausal women where all estrogens and practically all androgens are made at their site of action in peripheral tissues from DHEA, the precursor of adrenal origin. In men, on the other hand, from 40 to 50% of androgens are made in peripheral tissues from adrenal DHEA, thus indicating the major importance of the intracrine pathways in both men and women. We also examine the molecular evolution of steroidogenic enzymes which explains the major differences in steroid metabolism observed between laboratory animals and humans.

Genomic analysis of cancer tissue reveals that somatic mutations commonly occur in a specific motif

Somatic mutations are hallmarks of cancer progression. We sequenced 26 matched human prostate tumor and constitutional DNA samples for somatic alterations in the SRD5A2, HPRT, and HSD3B2 genes, and identified 71 nucleotide substitutions. Of these substitutions, 79% (56/71) occur within a WKVnRRRnVWK sequence (a novel motif we call THEMIS [from the ancient Greek goddess of prophecy]: W=A/T, K=G/T, V=G/A/C, R=purine (A/G), and n=any nucleotide), with one mismatch allowed. Literature searches identified this motif with one mismatch allowed in 66% (37/56) of the somatic prostate cancer mutations and in 74% (90/122) of the somatic breast cancer mutations found in all human genes analyzed. We also found the THEMIS motif with one allowed mismatch in 88% (23/26) of the ras1 gene somatic mutations formed in the sensitive to skin carcinogenesis (SENCAR) mouse model, after induction of error-prone DNA repair following mutagenic treatment. The high prevalence of the motif in each of the above mentioned cases cannot be explained by chance (P<0.046). We further identified 27 somatic mutations in the error-prone DNA polymerase genes pol eta, pol kappa, and pol beta in these prostate cancer patients. The data suggest that most somatic nucleotide substitutions in human cancer may occur in sites that conform to the THEMIS motif. These mutations may be caused by "mutator" mutations in error-prone DNA polymerase genes.

A lifetime of aldosterone excess: long-term consequences of altered regulation of aldosterone production for cardiovascular function

Up to 15% of patients with essential hypertension have inappropriate regulation of aldosterone; although only a minority have distinct adrenal tumors, recent evidence shows that mineralocorticoid receptor activation contributes to the age-related blood pressure rise and illustrates the importance of aldosterone in determining cardiovascular risk. Aldosterone also has a major role in progression and outcome of ischemic heart disease. These data highlight the need to understand better the regulation of aldosterone synthesis and its action. Aldosterone effects are mediated mainly through classical nuclear receptors that alter gene transcription. In classic epithelial target tissues, signaling mechanisms are relatively well defined. However, aldosterone has major effects in nonepithelial tissues that include increased synthesis of proinflammatory molecules and reactive oxygen species; it remains unclear how these effects are controlled and how receptor specificity is maintained. Variation in aldosterone production reflects interaction of genetic and environmental factors. Although the environmental factors are well understood, the genetic control of aldosterone synthesis is still the subject of debate. Aldosterone synthase (encoded by the CYP11B2 gene) controls conversion of deoxycorticosterone to aldosterone. Polymorphic variation in CYP11B2 is associated with increased risk of hypertension, but the molecular mechanism that accounts for this is not known. Altered 11beta-hydroxylase efficiency (conversion of deoxycortisol to cortisol) as a consequence of variation in the neighboring gene (CYP11B1) may be important in contributing to altered control of aldosterone synthesis, so that the risk of hypertension may reflect a digenic effect, a concept that is discussed further. There is evidence that a long-term increase in aldosterone production from early life is determined by an interaction of genetic and environmental factors, leading to the eventual phenotypes of aldosterone-associated hypertension and cardiovascular damage in middle age and beyond. The importance of aldosterone has generated interest in its therapeutic modulation. Disadvantages associated with spironolactone (altered libido, gynecomastia) have led to a search for alternative mineralocorticoid receptor antagonists. Of these, eplerenone has been shown to reduce cardiovascular risk after myocardial infarction. The benefits and disadvantages of this therapeutic approach are discussed.

Androgen biosynthetic pathways in the human prostate

It is well recognized that there are two androgens, namely testosterone (T) and dihydrotestosterone (DHT); T plays an important role in the testis and muscle, and DHT is crucial for the development, function and pathology of the prostate. It is generally thought that DHT is produced from the 5alpha-reduction of circulating T before being inactivated by 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD) that converts DHT into 5alpha-androstane-3alpha,17beta-diol (3alpha-diol). However, the presence of various steroidogenic enzymes in the prostate as well as the availability at high levels of various steroid precursors such as dehydroepiandrosterone sulphate (DHEAS), dehydroepiandrosterone (DHEA) and 4-androstenedione (4-dione) strongly suggest the existence of additional pathways involved in the biosynthesis and metabolism of DHT. Because steroidogenesis could be different in different species, data from the literature obtained from various human, dog, rat and mouse prostate tissues, as well as primary cells and prostatic cancer cell lines, provide a somewhat confusing picture. In the present chapter, we review the data in order to provide a clearer picture of the pathways involved in DHT biosynthesis and metabolism in the human prostate.

SRD5A2 and HSD3B2 polymorphisms are associated with prostate cancer risk and aggressiveness

BACKGROUND

Dihydrotestosterone (DHT) is believed to play an important role in prostate carcinogenesis. Five alpha reductase type II (SRD5A2) and 3 beta-hydroxysteroid dehydrogenase type II (HSD3B2) are responsible for the biosynthesis and degradation of DHT in the prostate. Two polymorphisms, a valine (V) for leucine (L) substitution at the 89 codon of the SRD5A2 gene and a (TG)n,(TA)n,(CA)n repeat polymorphism within the third intron of the HSD3B2 gene were evaluated with regard to prostate cancer risk.

METHODS

Blood samples were collected for 637 prostate cancer cases and 244 age and race frequency matched controls. In analysis, the SRD5A2 VL and LL genotypes were combined into one group and the HSD3B2 repeat polymorphism was dichotomized into short (<283) and long (> or =283) alleles.

RESULTS

The SRD5A2 V89L polymorphism was not independently associated with prostate cancer risk. Carriage of at least one HSD3B2 intron 3 intron 3 short allele was associated with a significant increased risk for prostate cancer among all subjects (OR = 2.07, 95% CI = 1.08-3.95, P = 0.03) and Caucasians (OR = 2.80, CI = 2.80-7.43, P = 0.04), but not in African Americans (OR = 1.50, CI = 0.62-3.60, P = 0.37). Stratified analyses revealed that most of the prostate cancer risk associated with the intron 3 HSD3B2 short allele was confined to the SRD5A2 89L variant subgroup and indicated that in combination these polymorphisms may be associated with increased risk of aggressive (Gleason >7) disease (Gleason >7).

CONCLUSIONS

In Caucasians, the HSD3B2 (TG)n,(TA)n,(CA)n intron 3 length polymorphism is associated with both prostate cancer risk and aggressiveness and the SRD5A2 V89L polymorphism may modify the risk conferred by this polymorphism.

Human 3beta-hydroxysteroid dehydrogenase types 1 and 2: Gene sequence variation and functional genomics

The 3beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4) isomerase isoenzymes 1 and 2 (HSD3B1 and HSD3B2) are membrane-bound enzymes that play essential roles in the biosynthesis of steroid hormones. Therefore, variation in the HSD3B1 and HSD3B2 genes might play a role in the pathophysiology of steroid hormone-related disease. We set out to systematically identify common polymorphisms and haplotypes in human HSD3B1 and HSD3B2. We identified 17 single nucleotide polymorphisms (SNPs) in HSD3B1 and 9 in HSD3B2 - the majority of which were not present in public databases - by resequencing human HSD3B1 and HSD3B2 using 240 DNA samples from four different ethnic groups (60 samples per group). Functional genomic studies of the five non-synonymous cSNPs in HSD3B1 and the one observed in HSD3B2 showed that two of these polymorphisms resulted in significant decreases in the quantity of enzyme protein expressed. However, none of the three non-synonymous SNPs located in areas encoding putative membrane-binding domains altered subcellular localization of the enzyme as determined by immunofluorescence microscopy. Finally, common variant haplotypes in the 5'-flanking regions of these genes showed significant cell line-dependent variation in their ability to drive transcription. In aggregate, these results provide a basis for study of the possible role in human disease of common genetic variation in HSD3B1 and HSD3B2.

Enzyme kinetics of zearalenone biotransformation: pH and cofactor effects

The aim of the present study was to investigate the hepatic biotransformation of the mycotoxin zearalenone (ZEA) in vitro using subcellular fractions of pig livers. The dependencies of the enzymatic reactions involved on the enzyme velocity, on the cofactor and on pH were analysed in both the microsomal fraction and the post-mitochondrial cell fraction. Finally, the inhibitory effects of various endogenous substrates on the enzymes involved (3alpha- and 3beta-hydroxysteroid dehydrogenase) were examined. Significant differences were observed between the individual subcellular fractions in terms of prevailing metabolites and absolute amounts of the metabolites produced. Moreover, this study also demonstrated that the reactions for both subcellular fractions of porcine liver are dependent on the cofactor, as alpha-zearalenol (alpha-ZOL) formation increased in the presence of NADPH, whereas beta-zearalenol (beta-ZOL) production only increased in the presence of NADH (P<0.001). The optimal pH for alpha-ZOL production was pH 5.6 and that for beta-ZOL formation pH 7.4. Subsequent inhibition studies showed significant inhibitory effects for 5alpha-androstanedione>androstanedione>pregnenolone on alpha-ZOL formation, whereas beta-ZOL production was only inhibited by pregnenolone. Finally, the contributions of 3alpha- and 3beta-hydroxysteroid dehydrogenase during the bioconversion of ZEA are discussed in the context of these experiments.

Molecular biology of the 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase gene family

The 3beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4) isomerase (3beta-HSD) isoenzymes are responsible for the oxidation and isomerization of Delta(5)-3beta-hydroxysteroid precursors into Delta(4)-ketosteroids, thus catalyzing an essential step in the formation of all classes of active steroid hormones. In humans, expression of the type I isoenzyme accounts for the 3beta-HSD activity found in placenta and peripheral tissues, whereas the type II 3beta-HSD isoenzyme is predominantly expressed in the adrenal gland, ovary, and testis, and its deficiency is responsible for a rare form of congenital adrenal hyperplasia. Phylogeny analyses of the 3beta-HSD gene family strongly suggest that the need for different 3beta-HSD genes occurred very late in mammals, with subsequent evolution in a similar manner in other lineages. Therefore, to a large extent, the 3beta-HSD gene family should have evolved to facilitate differential patterns of tissue- and cell-specific expression and regulation involving multiple signal transduction pathways, which are activated by several growth factors, steroids, and cytokines. Recent studies indicate that HSD3B2 gene regulation involves the orphan nuclear receptors steroidogenic factor-1 and dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome gene 1 (DAX-1). Other findings suggest a potential regulatory role for STAT5 and STAT6 in transcriptional activation of HSD3B2 promoter. It was shown that epidermal growth factor (EGF) requires intact STAT5; on the other hand IL-4 induces HSD3B1 gene expression, along with IL-13, through STAT 6 activation. However, evidence suggests that multiple signal transduction pathways are involved in IL-4 mediated HSD3B1 gene expression. Indeed, a better understanding of the transcriptional factors responsible for the fine control of 3beta-HSD gene expression may provide insight into mechanisms involved in the functional cooperation between STATs and nuclear receptors as well as their potential interaction with other signaling transduction pathways such as GATA proteins. Finally, the elucidation of the molecular basis of 3beta-HSD deficiency has highlighted the fact that mutations in the HSD3B2 gene can result in a wide spectrum of molecular repercussions, which are associated with the different phenotypic manifestations of classical 3beta-HSD deficiency and also provide valuable information concerning the structure-function relationships of the 3beta-HSD superfamily. Furthermore, several recent studies using type I and type II purified enzymes have elegantly further characterized structure-function relationships responsible for kinetic differences and coenzyme specificity.

Gonadotropin-releasing hormone agonists in the treatment of prostate cancer

In 1979, the first prostate cancer patient was treated with a GnRH agonist at the Laval University Medical Center in Quebec City, Canada, thus rapidly leading to the worldwide replacement of surgical castration and high doses of estrogens. The discovery of medical castration with GnRH agonists was soon followed by fundamental changes in the endocrine therapy of prostate cancer. Most importantly, the excellent tolerance accompanying the treatment with GnRH agonists has been a key factor that permitted a series of studies demonstrating a major reduction in the death rate from prostate cancer ranging from 31 to 87% at 5 yr of follow-up in patients with localized or locally advanced prostate cancer. In fact, a one third reduction in prostate cancer deaths has been calculated in the metaanalysis of all available studies. The general acceptance of this discovery by patients and physicians is illustrated by world sales above 3.0 billion U.S. dollars in 2003. Although extremely efficient in achieving complete medical castration and well tolerated, with no other side effects than the expected hypoandrogenicity, GnRH agonists should not be administered alone. In fact, shortly after discovery of the castration effects of GnRH agonists, we observed that approximately 50% of androgens remain in the prostate after castration, thus leading to the recognition of the role of adrenal dehydroepiandrosterone as an important source of the androgens synthesized locally in the prostate and in many peripheral target tissues. We therefore developed combined androgen blockade (CAB), whereby the androgens of both testicular and adrenal origins are blocked simultaneously at start of treatment with the combination of a GnRH agonist to block the testis and a pure antiandrogen to block the action of the androgens produced locally. CAB, first used in advanced metastatic disease, has been the first treatment shown to prolong life in prostate cancer. Most interestingly, in 2002, we made the observation that CAB alone given continuously for 6.5 yr or more leads to cure of the disease in at least 90% of cases, thus suggesting that androgen blockade combining a GnRH agonist and a pure antiandrogen could well be the most efficient treatment of localized prostate cancer, and thus offering the possibility of practically eliminating death from prostate cancer.

Refining hormonal diagnosis of type II 3beta-hydroxysteroid dehydrogenase deficiency in patients with premature pubarche and hirsutism based on HSD3B2 genotyping

Congenital adrenal hyperplasia due to 3beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4)-isomerase (3betaHSD), a rare autosomal recessive disorder that affects both sexes, has a heterogeneous clinical presentation ranging from the severe salt-wasting to the non-salt-wasting forms and results from mutations in the HSD3B2 gene. The hormonal criteria for diagnosing the mild variant of 3betaHSD deficiency have been controversial because the initial studies were not based on genetic evidence. We investigated the relationship between the hormonal phenotype and HSD3B2 genotype in 22 patients with clinical and/or biochemical features suggestive of 3betaHSD2 deficiency, including nine female children with premature pubarche, 12 hirsute females, and one boy with salt-wasting and ambiguous genitalia. Serum 17-hydroxypregnenolone (Delta5-17P), cortisol (F), 17-hydroxyprogesterone, dehydroepiandrosterone, and androstenedione levels were determined by RIA and were compared with Tanner pubic hair stage-matched control groups. The genomic DNA was extracted, and the entire HSD3B2 gene was amplified by PCR followed by automatic sequencing. Besides two different mutations previously observed in three patients (T259M and G129R/P222Q mutations), we observed the P222Q mutation in the male patient with salt-wasting form of 3betaHSD2 deficiency. Basal and ACTH-stimulated Delta5-17P levels (nanomoles per liter) ranged from 4-41 (-0.2 to 14 sd) and 36-97 (3.5-15.5 sd), respectively, in patients without mutation in HSD3B2 and from 69-153 (25-57 sd) and 201-351 (36-65 sd), respectively, in patients with mutation in HSD3B2. Basal and ACTH-stimulated Delta5-17P to F ratios ranged from 11-159 (0.5-25 sd) and 42-122 (2.4-11.3 sd), respectively, in patients without mutation in HSD3B2 and from 181-1700 (29-282 sd) and 487-1523 (52-167 sd), respectively, in patients with mutation in HSD3B2. The hormone findings in the genotype-proven patients suggest that the following hormonal criteria are compatible with 3betaHSD2 deficiency in children with premature pubarche: ACTH-stimulated Delta5-17P and Delta5-17P to F ratios at or greater than 201 and 487 nmol/liter, respectively, equivalent to or greater than 36 and 52 sd above matched control mean. Basal and ACTH-stimulated Delta5-17P and Delta5-17P to F ratios in all genotype-proven patients in childhood were unequivocally higher than the levels of either genotype-normal patients. All the other parameters overlapped between the patients with and without mutations in the HSD3B2 gene. In conclusion, genotyping more patients in the present study, we confirm that patients with mutations in the HSD3B2 gene have extremely elevated basal and ACTH-stimulated Delta5-17P levels and Delta5-17P to F ratios. Therefore, these data refine the hormonal criteria proposed to predict more accurately 3betaHSD2 deficiency.

Inhibition of human-type 1 3beta-hydroxysteroid deshydrogenase/Delta(5)-Delta(4)-isomerase expression using siRNA

Specific inhibition of type 1 3beta-HSD is of particular interest since it will allow us to control the formation of androgens and estrogens in peripheral target tissues without affecting type 2 3beta-HSD, which is responsible for the biosynthesis of glucocorticoids and mineralocorticoids in the adrenals. The high homology between types 1 and 2 3beta-HSD is a major difficulty in the development of specific inhibitors through classical chemical synthesis. In this report, we describe the use of small interference RNA (siRNA) to specifically inhibit human type 1 3beta-HSD. We have constructed three DNA vector-based RNAi vectors that allow us to produce three RNA duplexes of 21 nucleotides targeting three different coding regions of human type 1 3beta-HSD mRNA. The resulting constructs were co-transfected into HEK-293 cells with a vector expressing type 1 3beta-HSD. The results indicate that while the two duplexes that target sequences in the 5'-region do not have a strong inhibitory effect, the duplex that targets the 3'-region efficiently inhibits 3beta-HSD activity. Up to 98% inhibition has been observed. To our knowledge, this is the first report showing successful inhibition of steroidogenic enzymes using siRNA technology.

Quantitative appreciation of steroidogenic gene expression in mouse tissues: new roles for type 2 5alpha-reductase, 20alpha-hydroxysteroid dehydrogenase and estrogen sulfotransferase

We have recently developed an improved method for the RealTime PCR quantification of reversed transcribed mRNA (Q_RTPCR) that allows to obtain absolute mRNA expression levels with high sensitivity and accuracy. Using this Q_RTPCR method to assess the mRNA expression levels of genes encoding steroidogenic enzymes in male and female mouse tissues allows us to gain quantitative appreciation of the function of these genes. We could thus identify the existence of two types of steroidogenic tissues: those of classical endocrine glands such as the testis, ovary and adrenals which deliver steroids into the circulation, and in which millions of copies/mug total RNA are detected, and those of peripheral intracrine tissues where steroids are synthesized locally and exert their action at the site where they are produced (prostate, uterus, etc.), and in which the expression level of steroidogenic enzymes is much lower. We also observed an abnormally high expression levels of type 2 5alpha-reductase and 20alpha-HSD in the male and female adrenals, respectively, thus indirectly suggesting new roles for these sex-specific enzymes. On the other hand estrogen sulfotransferase, the enzyme that inactivates estrogen, has been found selectively expressed in male tissues, thus suggesting a role for this enzyme to protect male-specific tissues against estrogenic activity.

Effect of trilostane on serum concentrations of aldosterone, cortisol, and potassium in dogs with pituitary-dependent hyperadrenocorticism

OBJECTIVE

To evaluate the effect of trilostane on serum concentrations of aldosterone, cortisol, and potassium in dogs with pituitary-dependent hyperadrenocorticism (PDH), compare the degree of reduction of aldosterone with that of cortisol, and compare aldosterone concentrations of healthy dogs with those of dogs with PDH.

ANIMALS

17 dogs with PDH and 12 healthy dogs.

PROCEDURE

For dogs with PDH, the initial dose of trilostane was selected in accordance with body weight. A CBC count, serum biochemical analyses, and ACTH stimulation tests were performed in each dog. Dogs were evaluated 1, 3 to 4, 6 to 8, and 10 to 12 weeks after initiation of treatment. Healthy dogs were evaluated only once.

RESULTS

Serum aldosterone concentrations before ACTH stimulation did not change significantly after initiation of treatment with trilostane. At each evaluation after initiation of treatment, serum aldosterone concentrations after ACTH stimulation were significantly lower than corresponding concentrations before initiation of treatment. The overall effect of trilostane on serum aldosterone concentration was less pronounced than the effect on serum cortisol concentration. Median potassium concentrations increased slightly after initiation of treatment with trilostane. Dogs with PDH had significantly higher serum aldo sterone concentrations before and after ACTH stimulation than healthy dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment with trilostane resulted in a reduction in serum cortisol and aldosterone concentrations in dogs with PDH, although the decrease for serum aldosterone concentration was smaller than that for serum cortisol concentration. There was no correlation between serum concentrations of aldosterone and potassium during treatment.

The NGFI-B family of transcription factors regulates expression of 3beta-hydroxysteroid dehydrogenase type 2 in the human ovary

The nerve growth factor-induced clone B (NGFI-B) family of transcription factors are orphan members of the steroid hormone receptor superfamily. The NGFI-B expression was recently shown in the rat ovarian tissue and appears to be regulated by gonadotrophins. The purpose of our study was to investigate the role of the three members of this family [NGFI-B, Nur-related factor 1 (NURR1) and neuron derived orphan receptor 1 (NOR-1)] in the transcription of genes that encode key steroidogenic enzymes and examine expression in the human ovary. Real-time RT-PCR was used to quantify mRNA expression levels of the NGFI-B family members in human ovarian follicles, corpora lutea and in human granulosa cells after FSH, phorbol ester (TPA) and forskolin treatment. NGFI-B was expressed at higher levels than both NURR1 and NOR-1 in both ovarian follicles and corpora lutea. In human granulosa tumour (HGT) cells, the NGFI-B expression increased after TPA, and to a lesser extent, after forskolin treatment. Treatment of primary cultures of human granulosa cells with forskolin and FSH rapidly increased the NGFI-B mRNA levels followed by an increase in 3beta-hydroxysteroid dehydrogenase type 2 (HSD3B2). Transcription of HSD3B2 was studied by transfecting NGFI-B and steroidogenic factor 1 (SF1) expression vectors with reporter constructs prepared with human steroidogenic acute regulatory protein, cholesterol side-chain cleavage, and HSD3B2 genes. NGFI-B increased the transcription of HSD3B2 in HGT cells which is significantly more than SF1. Mutation or deletion of the NGFI-B response element in the HSD3B2 promoter significantly reduced the NGFI-B-mediated transcription of HSD3B2. Therefore, our data suggest that the NGFI-B may play a significant role in up-regulation of HSD3B2 that leads to the increase in progesterone production that is seen in granulosa cells at ovulation.

Local synthesis and dual actions of progesterone in the nervous system: neuroprotection and myelination

Progesterone (PROG) is synthesized in the brain, spinal cord and peripheral nerves. Its direct precursor pregnenolone is either derived from the circulation or from local de novo synthesis as cytochrome P450scc, which converts cholesterol to pregnenolone, is expressed in the nervous system. Pregnenolone is converted to PROG by 3beta-hydroxysteroid dehydrogenase (3beta-HSD). In situ hybridization studies have shown that this enzyme is expressed throughout the rat brain, spinal cord and dorsal root ganglia (DRG) mainly by neurons. Macroglial cells, including astrocytes, oligodendroglial cells and Schwann cells, also have the capacity to synthesize PROG, but expression and activity of 3beta-HSD in these cells are regulated by cellular interactions. Thus, Schwann cells convert pregnenolone to PROG in response to a neuronal signal. There is now strong evidence that P450scc and 3beta-HSD are expressed in the human nervous system, where PROG synthesis also takes place. Although there are only a few studies addressing the biological significance of PROG synthesis in the brain, the autocrine/paracrine actions of locally synthesized PROG are likely to play an important role in the viability of neurons and in the formation of myelin sheaths. The neuroprotective effects of PROG have recently been documented in a murine model of spinal cord motoneuron degeneration, the Wobbler mouse. The treatment of symptomatic Wobbler mice with PROG for 15 days attenuated the neuropathological changes in spinal motoneurons and had beneficial effects on muscle strength and the survival rate of the animals. PROG may exert its neuroprotective effects by regulating expression of specific genes in neurons and glial cells, which may become hormone-sensitive after injury. The promyelinating effects of PROG were first documented in the mouse sciatic nerve and in co-cultures of sensory neurons and Schwann cells. PROG also promotes myelination in the brain, as shown in vitro in explant cultures of cerebellar slices and in vivo in the cerebellar peduncle of aged rats after toxin-induced demyelination. Local synthesis of PROG in the brain and the neuroprotective and promyelinating effects of this neurosteroid offer interesting therapeutic possibilities for the prevention and treatment of neurodegenerative diseases, for accelerating regenerative processes and for preserving cognitive functions during aging.

Molecular study of the 3 beta-hydroxysteroid dehydrogenase gene type II in patients with hypospadias

To determine whether some patients with idiopathic hypospadias have HSD3B2 mutations, we genotyped this locus in 90 patients with hypospadias (age, 6.0 +/- 0.4 yr) and 101 healthy fertile male controls. We measured basal plasma renin activity and performed an ACTH test for determination of 17-OH-pregnenolone, 17-OH-progesterone, cortisol, dehydroepiandrosterone sulfate, and androstenedione and an human chorionic gonadotropin test for determination of androstenedione, testosterone, and dihydrotestosterone. We did not observe a clear steroidogenic pattern suggestive of 3 beta-HSD deficiency in any patient. DNA was extracted from peripheral lymphocytes; and exons 1, 2, 3, and 4 were amplified by PCR and analyzed by denaturing gradient gel electrophoresis. An abnormal electrophoretic migration pattern of exon 4 was observed in five patients. Two patients had missense heterozygous mutations (S213T and S284R). In another three patients, we observed heterozygous nucleotide variants in exon 4 that did not produce a change in amino acids (A238, T259, T320). In vitro enzymatic activity was diminished by 40% and 32% in the S213T and S284R heterozygous mutations, respectively. One control exhibited a heterozygous mutation in exon 3 (V78I), which did not alter in vitro enzyme activity. In addition, we observed possible polymorphisms in intron 1 in four patients and one control. We conclude that subtle molecular abnormalities in the HSD3B2 gene may be observed in some patients with apparent idiopathic hypospadias but that this finding is uncommon.

Steroid hormones and neurosteroids in normal and pathological aging of the nervous system

Without medical progress, dementing diseases such as Alzheimer's disease will become one of the main causes of disability. Preventing or delaying them has thus become a real challenge for biomedical research. Steroids offer interesting therapeutical opportunities for promoting successful aging because of their pleiotropic effects in the nervous system: they regulate main neurotransmitter systems, promote the viability of neurons, play an important role in myelination and influence cognitive processes, in particular learning and memory. Preclinical research has provided evidence that the normally aging nervous system maintains some capacity for regeneration and that age-dependent changes in the nervous system and cognitive dysfunctions can be reversed to some extent by the administration of steroids. The aging nervous system also remains sensitive to the neuroprotective effects of steroids. In contrast to the large number of studies documenting beneficial effects of steroids on the nervous system in young and aged animals, the results from hormone replacement studies in the elderly are so far not conclusive. There is also little information concerning changes of steroid levels in the aging human brain. As steroids present in nervous tissues originate from the endocrine glands (steroid hormones) and from local synthesis (neurosteroids), changes in blood levels of steroids with age do not necessarily reflect changes in their brain levels. There is indeed strong evidence that neurosteroids are also synthesized in human brain and peripheral nerves. The development of a very sensitive and precise method for the analysis of steroids by gas chromatography/mass spectrometry (GC/MS) offers new possibilities for the study of neurosteroids. The concentrations of a range of neurosteroids have recently been measured in various brain regions of aged Alzheimer's disease patients and aged non-demented controls by GC/MS, providing reference values. In Alzheimer's patients, there was a general trend toward lower levels of neurosteroids in different brain regions, and neurosteroid levels were negatively correlated with two biochemical markers of Alzheimer's disease, the phosphorylated tau protein and the beta-amyloid peptides. The metabolism of dehydroepiandrosterone has also been analyzed for the first time in the aging brain from Alzheimer patients and non-demented controls. The conversion of dehydroepiandrosterone to Delta5-androstene-3beta,17beta-diol and to 7alpha-OH-dehydroepiandrosterone occurred in frontal cortex, hippocampus, amygdala, cerebellum and striatum of both Alzheimer's patients and controls. The formation of these metabolites within distinct brain regions negatively correlated with the density of beta-amyloid deposits.

Endocrine and intracrine sources of androgens in women: inhibition of breast cancer and other roles of androgens and their precursor dehydroepiandrosterone

Serum androgens as well as their precursors and metabolites decrease from the age of 30-40 yr in women, thus suggesting that a more physiological hormone replacement therapy at menopause should contain an androgenic compound. It is important to consider, however, that most of the androgens in women, especially after menopause, are synthesized in peripheral intracrine tissues from the inactive precursors dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S) of adrenal origin. Much progress in this new area of endocrine physiology called intracrinology has followed the cloning and characterization of most of the enzymes responsible for the transformation of DHEA and DHEA-S into androgens and estrogens in peripheral target tissues, where the locally produced sex steroids are exerting their action in the same cells in which their synthesis takes place without significant diffusion into the circulation, thus seriously limiting the interpretation of serum levels of active sex steroids. The sex steroids made in peripheral tissues are then inactivated locally into more water-soluble compounds that diffuse into the general circulation where they can be measured. In a series of animal models, androgens and DHEA have been found to inhibit breast cancer development and growth and to stimulate bone formation. In clinical studies, DHEA has been found to increase bone mineral density and to stimulate vaginal maturation without affecting the endometrium, while improving well-being and libido with no significant side effects. The advantage of DHEA over other androgenic compounds is that DHEA, at physiological doses, is converted into androgens and/or estrogens only in the specific intracrine target tissues that possess the appropriate physiological enzymatic machinery, thus limiting the action of the sex steroids to those tissues possessing the tissue-specific profile of expression of the genes responsible for their formation, while leaving the other tissues unaffected and thus minimizing the potential side effects observed with androgens or estrogens administered systemically.

Genomics of steroid hormones: in silico analysis of nucleotide sequence variants (polymorphisms) of the enzymes involved in the biosynthesis and metabolism of steroid hormones

Alterations of steroid hormone biosynthesis and metabolism are suspected to be involved in the pathogenesis of several diseases. Several polymorphisms of the enzymes involved in these processes have already been described and some could be associated with certain diseases. We attempted to examine the sequence variants of these genes in order to find novel variants by an in silico analysis. We analyzed the known human nucleotide sequences of the enzymes p450 side-chain cleavage enzyme, steroid 17-alpha-hydroxylase/17,20-lyase, 3-beta-hydroxysteroid dehydrogenase types 1 and 2, 21-hydroxylase, 11-beta-hydroxylase, aldosterone synthase, aromatase, 11-beta-hydroxysteroid dehydrogenase types 1 and 2, steroid 5-alpha-reductase types 1 and 2, steroid 5-beta-reductase, dehydroepiandrosterone sulfotransferase, 17-beta-hydroxysteroid dehydrogenase types 1-3. The analysis was performed using the National Center for Biotechnology Information Database by the search tool blastn. We found numerous sequence variants in both coding and non-coding sequences. The majority of these sequence variants have already been described, nevertheless, some appear as novel variants. Some of these may also have functional significance. We hypothesize over the possible significance of these findings and briefly review the available literature.

Glucocorticoids enhance activation of the human type II 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase gene

Glucocorticoids indirectly alter adrenocortical steroid output through the inhibition of ACTH secretion by the anterior pituitary. However, previous studies suggest that glucocorticoids can directly affect adrenocortical steroid production. Therefore, we have investigated the ability of glucocorticoids to affect transcription of adrenocortical steroid biosynthetic enzymes. One potential target of glucocorticoid action in the adrenal is an enzyme critical for adrenocortical steroid production: 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase (3beta-HSD). Treatment of the adrenocortical cell line (H295R) with the glucocorticoid agonist dexamethasone (DEX) increased cortisol production and 3beta-HSD mRNA levels alone or in conjunction with phorbol ester. This increase in 3beta-HSD mRNA was paralleled by increases in Steroidogenic Acute Regulatory Protein (StAR) mRNA levels. The human type II 3beta-HSD promoter lacks a consensus palindromic glucocorticoid response element (GRE) but does contain a Stat5 response element (Stat5RE) suggesting that glucocorticoids could affect type II 3beta-HSD transcription via interaction with Stat5. Transfection experiments show enhancement of human type II 3beta-HSD promoter activity by coexpression of the glucocorticoid receptor (GR) and Stat5A and treatment with 100nM dexamethasone. Furthermore, removal of the Stat5RE either by truncation of the 5' flanking sequence in the promoter or introduction of point mutations to the Stat5RE abolished the ability of DEX to enhance 3beta-HSD promoter activity. These studies demonstrate the ability of glucocorticoids to directly enhance the expression of an adrenal steroidogenic enzyme gene albeit independent of a consensus palindromic glucocorticoid response element.

The murine 3beta-hydroxysteroid dehydrogenase (3beta-HSD) gene family: a postulated role for 3beta-HSD VI during early pregnancy

The enzyme 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD) is essential for the biosynthesis of all active steroid hormones. The 3beta-HSD enzyme consists in multiple isoforms, each the product of a distinct gene. In the mouse, six tissue-specific isoforms have been identified. These isoforms are expressed in a tissue- and temporal specific manner. Mouse 3beta-HSD VI is the only isoform expressed in decidua and giant trophoblast cells during the first half of mouse pregnancy. The tissue- and temporal-specific expression of 3beta-HSD VI during mouse pregnancy, as determined by in situ hybridization and immunohistochemistry, shows that 3beta-HSD is expressed exclusively in the antimesometrial decidua on E6.5 and E7.5. By E9.5, expression of 3beta-HSD is observed in giant trophoblast cells with a marked increase in expression by E10.5. No expression of 3beta-HSD is seen in decidua after E7.5 and no expression of 3beta-HSD is seen in the embryo at any of the times investigated. Giant trophoblast cells in culture from E9.5 and E10.5 synthesize progesterone with cells from E10.5 producing about 3.5-fold more progesterone during the first 24 h in culture. Western blot analysis of 3beta-HSD VI protein demonstrates that the amount of 3beta-HSD VI protein correlates with the amount of progesterone biosynthesis in giant trophoblast cells from E9.5 and E10.5. We propose that progesterone produced during the first half of mouse pregnancy in decidua and giant trophoblast cells acts as an immunosuppressant at the fetal maternal interface to prevent rejection of the fetus.

Anatomical and biochemical evidence for the synthesis of unconjugated and sulfated neurosteroids in amphibians

Various studies have shown that, in mammals, neurons and glial cells are capable of synthesizing bioactive steroids, or neurosteroids, which regulate the activity of the central nervous system (CNS). However, although steroid hormones are involved in the regulation of behavioral and neuroendocrine processes in amphibians, neurosteroid biosynthesis has never been studied in the CNS of non-mammalian vertebrates. Reviewed here are several data sets concerning the production of unconjugated and sulfated neurosteroids in amphibians. These data were obtained by investigating the immunohistochemical localization and activity of 3beta-hydroxysteroid dehydrogenase (3beta-HSD), 17beta-hydroxysteroid dehydrogenase (17beta-HSD) and hydroxysteroid sulfotransferase (HST), in the frog brain. Numerous 3beta-HSD-immunoreactive neurons were detected in the anterior preoptic area, nucleus of the periventricular organ, posterior tuberculum, ventral and dorsal hypothalamic nuclei. 17beta-HSD-like immunoreactivity was found in ependymal gliocytes bordering the lateral ventricles of the telencephalon. Two populations of HST-immunoreactive neurons were localized in the anterior preoptic area and the dorsal magnocellular nucleus of the hypothalamus. High amounts of progesterone (PROG), 17-hydroxyprogesterone (17OH-PROG), testosterone (T) and dehydroepiandrosterone sulfate (DHEAS) were measured in the frog brain by combining HPLC analysis of tissue extracts with radioimmunoassay detection. Incubation of telencephalic or hypothalamic explants with tritiated pregnenolone ([3H]PREG) yielded the synthesis of various metabolites including PROG, 17OH-PROG, DHEA and T. Incorporation of [35S]3'-phosphoadenosine 5'-phosphosulfate ([35S]PAPS) and [3H]PREG or [3H]DHEA into frog brain homogenates led to the formation of [3H,35S]pregnenolone sulfate ([3H,35S]PREGS) or [3H,35S]DHEAS, respectively. Altogether, these results demonstrate that the process of neurosteroid biosynthesis occurs in amphibians as previously seen in mammals.

cDNA cloning and physical mapping of porcine 3 beta-hydroxysteroid dehydrogenase/Delta 5-Delta 4 isomerase

The 3 beta-hydroxysteroid dehydrogenase/Delta 5-Delta 4-isomerase (3 beta-HSD) enzymes are essential for the biosynthesis of steroid hormones. The 3 beta-HSD gene family has been reported to encode for different isoenzymes which function either as dehydrogenase/isomerase or as reductase. The 3 beta-HSD enzymes are involved in the formation of the pheromone androstenone (5 alpha-androst-16-ene-3-one) which contributes to the unpleasant odour present in the meat of uncastrated boars. An reverse-transcription-polymerase chain reaction (RT-PCR) probe from porcine testicular tissue of a 3 beta-HSD enzyme was used to screen a porcine adipose tissue cDNA library. Both strands of the positive clones were sequenced and the putative coding sequence of 1122 nucleotides encodes 374 amino acids. Comparison of the putative open reading frame with the bovine and the human type I homologues revealed 85.6 and 79.3% identity, respectively. Fluorescence in situ hybridization (FISH) was performed with a labelled PAC clone containing the gene of interest. The 3 beta-HSD gene was mapped to the porcine chromosome 4q16-4q21 which is in accordance with the comparative gene map.

Immunohistochemical localization of 3 beta-hydroxysteroid dehydrogenase and 5 alpha-reductase in the brain of the African lungfish Protopterus annectens

The localization of the enzymes responsible for the biosynthesis of neurosteroids in the brain of dipnoans has not yet been determined. In the present study, we investigated the immunohistochemical distribution of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and 5 alpha-reductase (5 alpha-R) in the brain and pituitary of the African lungfish Protopterus annectens by using antibodies raised against type I human 3 beta-HSD and type I human 5 alpha-R. The 3 beta-HSD and 5 alpha-R immunoreactivities were detected in cell bodies and fibers located in the same areas of the lungfish brain, namely, in the pallium, thalamus, hypothalamus, tectum, and periaqueductal gray. Identification of astrocytes, oligodendrocytes, and neurons with antisera against glial fibrillary acidic protein, galactocerebroside and neurofilaments revealed that, in the lungfish brain, 3 beta-HSD immunolabeling is expressed exclusively by neurons, whereas the 5 alpha-R-immunoreactive material is contained in both neurons and glial cells. In the pituitary gland, 3 beta-HSD- and 5 alpha-R-like immunoreactivity was localized in both the pars distalis and the pars intermedia. The present study provides the first immunocytochemical mapping of two key steroidogenic enzymes in the brain and pituitary of a lungfish. These data strongly suggest that neurosteroid biosynthesis occurs in the brain of fishes, as previously shown for amphibians, birds, and mammals.

DHEA and its transformation into androgens and estrogens in peripheral target tissues: intracrinology

A new understanding of the endocrinology of menopause is that women, at menopause, are not only lacking estrogens resulting from cessation of ovarian activity but have also been progressively deprived for a few years of androgens and some estrogens originating from adrenal DHEA and androstenedione (4-dione). In fact, serum DHEA decreases by about 60% between the maximal levels seen at 30 years of age to the age of menopause. This decreased secretion of DHEA and DHEA-S by the adrenals is responsible for a parallel decrease in androgen and estrogen formation in peripheral tissues by the steroidogenic enzymes specifically expressed in each cell type in individual target tissues. This new field of endocrinology, called intracrinology, describes the local synthesis of androgens and estrogens made locally in each cell of each peripheral tissue from the adrenal precursors DHEA and 4-dione. These androgens and estrogens exert their action in the same cells where their synthesis takes place and they are released from these target cells only after being inactivated. To further understand the effect of DHEA in women, DHEA has been administered in postmenopausal women for 12 months. Such treatment resulted in increased bone formation and higher bone mineral density accompanied by elevated levels of osteocalcin, a marker of bone formation. Vaginal maturation was stimulated, while no effect was observed on the endometrium. Preclinical studies, on the other hand, have shown that, due to its predominant conversion into androgens, DHEA prevents the development and inhibits the growth of dimethylbenz(a)anthracene-induced mammary carcinoma in the rat, a model of breast cancer. DHEA also inhibits the growth of human breast cancer ZR-75-1 xenografts in nude mice. The inhibitory effect of DHEA on breast cancer is due to an androgenic effect of testosterone and dihydrotestosterone made locally from DHEA. When used as replacement therapy, DHEA is free of the potential risk of breast and uterine cancer, while it stimulates bone formation and vaginal maturation and decreases insulin resistance. The combination of DHEA with a fourth generation SERM, such as EM-652 (SCH 57068), a compound having pure and potent antiestrogenic activity in the mammary gland and endometrium, could provide major benefits for women at menopause (inhibition of bone loss and serum cholesterol levels) with the associated major advantages of preventing breast and uterine cancer. A widely used application of intracrinology is the treatment of prostate cancer where the testicles are blocked by an LHRH agonist while the androgens made locally in the prostate from DHEA are blocked by a pure antiandrogen. Such treatment, called combined androgen blockade, has led to the first demonstration of a prolongation of life in prostate cancer.

Congenital adrenal hyperplasia owing to 3 beta-hydroxysteroid dehydrogenase deficiency

Recent advances in the genetics of the family of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) enzymes have helped in the understanding of the molecular basis and hormonal phenotype of bona fide 3 beta-HSD deficiency congenital adrenal hyperplasia (CAH). This article revisits the clinical spectra of 3 beta-HSD deficiency disorders, pathophysiology of 3 beta-HSD deficiency CAH, and updates genotype findings and diagnostic hormonal criteria for bona fide classic and nonclassic 3 beta-HSD deficiency CAH. The delta-5 steroid abnormality for the nonclassic 3 beta-HSD deficiency CAH, proven by genotype study, is substantially greater than the hormonal criteria for the disorder published before the advent of molecular information on the gene encoding adrenals and gonads in humans. In hyperandrogenic children and women, the pathogenic mechanism of a subtle abnormality in adrenal 3 beta-HSD activity, determined by modestly elevated ACTH stimulated delta-5 steroid levels, which led to the diagnosis of mild nonclassic 3 beta-HSD deficiency in the past, is outside of the type II 3 beta-HSD gene which encodes adrenals and gonads in humans and remains to be further explored.

Analysis and characteristics of multiple types of human 17beta-hydroxysteroid dehydrogenase

Androgens and estrogens are not only synthesized in the gonads but also in peripheral target tissues. Accordingly, recent molecular cloning has allowed us to identify multiple types of 17beta-hydroxysteroid dehydrogenases (17beta-HSD), the key and exclusive enzymes involved in the formation and inactivation of sex steroids. However, only one form, namely, type 3 17beta-HSD, is responsible for pseudohermaphroditism in deficient boys. To date, seven human 17beta-HSDs have been isolated and characterized. Although they catalyze substrates having a similar structure, 17beta-HSDs have very low homology. In intact cells in culture, these enzymes catalyze the reaction in a unidirectional way - types 1, 3, 5 and 7 catalyze the reductive reaction, while types 2, 4 and 8 catalyze the oxidative reaction. It is noteworthy that rat type 6 17beta-HSD also catalyzes the reaction in the oxidative direction. In this report, we analyze the different characteristics of the multiple types of human 17beta-HSD.

3beta-hydroxysteroid dehydrogenase/delta5-->4-isomerase activity associated with the human 17beta-hydroxysteroid dehydrogenase type 2 isoform

The type 2 isoform of human 17beta-hydroxysteroid dehydrogenase (17betaHSD2) efficiently catalyzes the oxidative metabolism of androgens and estrogens, and it is expressed in a large series of human peripheral tissues. To obtain a better understanding of the regulation of local steroid biosynthesis and metabolism in human tissues, we have established a dual steroidogenic activity of the 17betaHSD2 enzyme after transfection of human 17betaHSD2-transfected human embryonic kidney (293) cells. After transient transfection, the metabolism of testosterone, pregnenolone, and dehydroepiandrosterone (DHEA) in intact transfected 293 cells was evaluated by TLC-based radiometric assays. 17betaHSD2-transfected cells converted 91% of testosterone (1 micromol/L) into androstenedione in a 2-h incubation period. In addition, pregnenolone (1 micromol/L) was converted to progesterone (18.5%), whereas DHEA (1 micromol/L) was metabolized to androstenedione (8.3% conversion) in a 15-h incubation period. The kinetics of the 3beta-hydroxysteroid dehydrogenase (3betaHSD) and 17betaHSD2 activities using cell homogenate protein of stably transfected 293 cells indicated that the catalytic efficiency (apparent catalytic efficiency = maximum velocity/Km) of this 3betaHSD activity is approximately 2000-fold (pregnenolone as substrate) or 3000-fold (DHEA as substrate) weaker than that of 17betaHSD2 activity. It is noteworthy, however, that the apparent catalytic efficiency of the HSD3B2 gene product is only approximately 50-fold higher than that of the 3betaHSD aspect of the 17betaHSD2 gene product. Pregnenolone or DHEA effectively inhibited 17betaHSD2 activity in a noncompetitive fashion. Furthermore, the potent 5alpha-reductase/3betaHSD inhibitor, 17beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5alpha-androstane-3-one , inhibited neither 3betaHSD nor 17betaHSD2 activities. We conclude that human 17betaHSD2 enzyme exhibits 3betaHSD activity. Notwithstanding that this 3betaHSD activity is reduced compared to 17betaHSD oxidative activity, it may account for at least some of the reports of 3betaHSD activity found in human peripheral tissues that express notable amounts of the 17betaHSD2 isozyme as well as in individuals with severe classic 3betaHSD deficiency.

Characterization of two novel homozygous missense mutations involving codon 6 and 259 of type II 3beta-hydroxysteroid dehydrogenase (3betaHSD) gene causing, respectively, nonsalt-wasting and salt-wasting 3betaHSD deficiency disorder

We identified two homozygous missense mutations in the human type II 3beta-hydroxysteroid dehydrogenase (3/betaHSD) gene, the first in codon 6 of exon II [CTT (Leu) to TTT (Phe)] in a male infant with hyperpigmented scrotum and hypospadias, raised as a male and no apparent salt-wasting since neonatal age, and the second in codon 259 of exon IV [ACG (Thr) to ATG (Met)] in a male pseudohermaphrodite with labial scrotal folds, microphallus, chordee, and fourth degree hypospadias, raised as a female and with salt-wasting disorder since neonatal age. In vitro transient expression of mutant type II 3betaHSD complementary DNAs of L6F, T259M, as well as T259R for comparison was examined by a site-directed mutagenesis and transfection of construct into COS-1 and COS-7 cells. Northern blot analysis revealed expression of similar amounts of type II 3betaHSD messenger ribonucleic acid from the COS-1 cells transfected by L6F, T259M, T259R, and wild-type (WT) complementary DNAs. Western immunoblot analysis revealed a similar amount of L6F mutant protein compared to WT enzyme from COS-1 cells, but neither L6F from COS-7 cells nor T259M or T259R mutant protein in COS-1 or COS-7 cells was detectable. Enzyme activity in intact COS-1 cells using 1 micromol/L pregnenolone as substrate in the medium after 6 h revealed relative conversion rates of pregnenolone to progesterone of 46% by WT enzyme, 22% by L6F enzyme, and 8% by T259M enzyme and less than 4% activity by T259R enzyme. Using 1 micromol/L dehydroepiandrosterone as substrate, the relative conversion rate of dehydroepiandrosterone to androstenedione after 6 was 89% by WT enzyme, 35% by L6F enzyme, 5.1% by T259M enzyme and no activity by T259R enzyme. However, the L6F mutant 3betaHSD activity, despite its demonstration in the intact cells, was not detected in homogenates of COS-1 cells or in immunoblots of COS-7 cells, suggestive of the relatively unstable nature of this protein in vitro, possibly attributable to the decreased 3betaHSD activity. In the case of T259M and T259R mutations, consistently undetectable proteins in both COS cells despite detectable messenger ribonucleic acids indicate severely labile proteins resulting in either no or very little enzyme activity, and these data further substantiate the deleterious effect of a structural change in this predicted putative steroid-binding domain of the gene. In conclusion, the findings of the in vitro study of mutant type II 3betaHSD enzyme activities correlated with a less severe clinical phenotype of nonsalt-wasting and a lesser degree of genital ambiguity in the patient with homozygous L6F mutation compared to a more severe clinical phenotype of salt-wasting and severe degree of genital ambiguity in the patient with homozygous T259M mutation in the gene.

A reliable PCR amplification method for microdissected tumor cells obtained from paraffin-embedded tissue

We report a reliable method for PCR (polymerase chain reaction) amplification of genomic DNA from PET. This method uses DNA extraction with the QIAquick kit and amplification with AmpliTaq Gold. Amplification of up to 959 bp from PET was achieved with this combination which exceeds the current reported upper limit of 800 bp. In summary, the gradual activation of the AmpliTaq Gold during thermal cycling allows both for higher-fidelity and higher-throughput PCR amplification from PET. The use of the QIAquick kit for DNA purification of PET is sensitive, reproducible and suitable for management of a high number of samples.

New insight into the molecular basis of 3beta-hydroxysteroid dehydrogenase deficiency: identification of eight mutations in the HSD3B2 gene eleven patients from seven new families and comparison of the functional properties of twenty-five mutant enzymes

Classical 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase (3betaHSD) deficiency is a form of congenital adrenal hyperplasia that impairs steroidogenesis in both the adrenals and gonads resulting from mutations in the HSD3B2 gene and causing various degrees of salt-wasting in both sexes and incomplete masculinization of the external genitalia in genetic males. To identify the molecular lesion(s) in the HSD3B2 gene in the 11 patients from the seven new families suffering from classical 3betaHSD deficiency, the complete nucleotide sequence of the whole coding region and exon-intron splicing boundaries of this gene was determined by direct sequencing. Five of these families were referred to Morel's molecular diagnostics laboratory in France, whereas the two other families were investigated by Peter's group in Germany. Functional characterization studies were performed by Simard's group in Canada. Following transient expression in 293 cells of each of the mutant recombinant proteins generated by site-directed mutagenesis, the effect of the 25 mutations on enzyme activity was assessed by incubating intact cells in culture with 10 nM [14C]-DHEA as substrate. The stability of the mutant proteins has been investigated using a combination of Northern and Western blot analyses, as well as an in vitro transcription/translation assay using rabbit reticulocyte lysates. The present report describes the identification of 8 mutations, in seven new families with individuals suffering from classical 3betaHSD deficiency, thus increasing the number of known HSD3B2 mutations involved in this autosomal recessive disorder to 31 (1 splicing, 1 in-frame deletion, 3 nonsense, 4 frameshift and 22 missense mutations). In addition to the mutations reported here in these new families, we have also investigated for the first time the functional significance of previously reported missense mutations and or sequence variants namely, A82T, A167V, L173R, L205P, S213G and K216E, P222H, T259M, and T259R, which have not previously been functionally characterized. Furthermore, their effects have been compared with those of the 10 previously reported mutant enzymes to provide a more consistent and comprehensive study. The present results are in accordance with the prediction that no functional 3betaHSD type 2 isoenzyme is expressed in the adrenals and gonads of the patients suffering from a severe salt-wasting form of CAH due to classical 3betaHSD deficiency. Whereas the nonsalt-losing form also results from missense mutation(s) in the HSD3B2 gene, which cause an incomplete loss in enzyme activity, thus leaving sufficient enzymatic activity to prevent salt wasting. The functional data described in the present study concerning the sequence variants A167V, S213G, K216E and L236S, which were detected with premature pubarche or hyperandrogenic adolescent girls suspected to be affected from nonclassical 3betaHSD deficiency, coupled with the previous studies reporting that no mutations were found in both HSD3B1 and/or HSD3B2 genes in such patients strongly support the conclusion that this disorder does not result from a mutant 3betaHSD isoenzyme. The present study provides biochemical evidence supporting the involvement of a new molecular mechanism in classical 3betaHSD deficiency involving protein instability and further illustrates the complexity of the genotype-phenotype relationships of this disease, in addition to providing further valuable information concerning the structure-function relationships of the 3betaHSD superfamily.

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.