Molecular Biology and Function of the Androgen Receptor in Genital Development

Development of a novel cell based androgen screening model

The androgen receptor (AR) mediates the majority of androgen effects on target cells. The DNA cis-regulatory elements that respond to AR share sequence similarity with cis-regulatory elements for glucocorticoid, mineralocorticoid and progesterone receptors (GR, MR and PR, respectively). As a result, many of the current AR screening models are complicated by inaccurate activation of reporters by one of these receptor pathways. Identification of more selective androgen testing systems would be beneficial for clinical, pharmacological and toxicologic screening of AR activators. The present study describes the development of a selective androgen-responsive reporter cell line that expresses AR but does not express GR, MR and PR. CV1 cells were stably transduced to express human AR and an androgen-responsive gaussia luciferase gene. Clonal populations of AR expressing cells were isolated. Quantitative RT-PCR (qPCR) and western analysis confirmed stable integration of AR in the most responsive clonal line which was named 'CV1-ARluc'. Stimulation of CV1AR-luc with androgenic ligands (testosterone and 5α-dihydrotestosterone) for 18h caused an increase in luciferase activity in a dose-dependent manner. Other steroid hormones including aldosterone, cortisol, and progesterone did not stimulate luciferase response. The CV1-ARluc also increased luciferase activity when treated with human serum extracts. In conclusion, the CV1-ARluc cells provide a novel model system for screening of new AR agonists and antagonists and can determine the androgenic activity of human serum samples.

Clinical, cytogenetic and molecular analysis of androgen insensitivity syndromes from south Indian cohort and detection and in-silico characterization of androgen receptor gene mutations

Rare cases of 9 complete androgen insensitivity syndromes, 9 cases of partial androgen insensitivity syndromes and equal number of male control samples were selected for this study. Few strong variations in clinical features were noticed; Giemsa banded metaphase revealed a 46,XY karyotype and the frequency of chromosome aberrations were significantly higher when compared with control samples. DNA sequence analysis of the androgen receptor gene of androgen insensitivity syndromes revealed three missense mutations - c.C1713>G resulting in the replacement of a highly conserved histidine residue with glutamine p.(His571Glu) in DNA-binding domain, c.A1715>G resulting in the replacement of a highly conserved tyrosine residue with cysteine p.(Tyr572Cys) in DNA-binding domain and c.G2599>A resulting in the replacement of a highly conserved valine residue with methionine p.(Val867Met) in ligand-binding domain of androgen receptor gene respectively. The heterozygous type of mutations c.C1713>G and c.G2599>A observed in mothers of the patients for familial cases concluding that the mutation was inherited from the mother. The novel mutation c.C1713>G is reported first time in androgen insensitivity syndrome. In-silico analysis of mutations observed in androgen receptor gene of androgen insensitivity syndrome predicted that the substitution at Y572C and V867M could probably disrupt the protein structure and function.

Familial complete androgen insensitivity syndrome with prostatic tissue and seminal vesicles

INTRODUCTION

Complete androgen insensitivity syndrome (CAIS) is a rare androgen receptor function disorder where phenotypic female has a male genotype. They mostly present as bilateral inguinal hernias containing testes. Uterus and cervix are absent.

MATERIALS AND METHODS

The authors present a case of CAIS in a 22-year-old female where the presence of testes, prostatic tissue and seminal vesicles was confirmed by ultrasonography, hormonal analysis, operative findings and histopathological study. She was second of the two sisters and her elder sister was also diagnosed with CAIS.

CONCLUSION

High levels of testosterone seen in CAIS can stimulate Wolffian duct development/differentiation. Gonadectomy is advisable in such patients to avoid future neoplastic changes.

Prostate epithelial cell fate

Androgen receptor (AR) within prostatic mesenchymal cells, with the absence of AR in the epithelium, is still sufficient to induce prostate development. AR in the luminal epithelium is required to express the secretory markers associated with differentiation. Nkx3.1 is expressed in the epithelium in early prostatic embryonic development and expression is maintained in the adult. Induction of the mouse prostate gland by the embryonic mesenchymal cells results in the organization of a sparse basal layer below the luminal epithelium with rare neuroendocrine cells that are interdispersed within this basal layer. The human prostate shows similar glandular organization; however, the basal layer is continuous. The strong inductive nature of embryonic prostatic and bladder mesenchymal cells is demonstrated in grafts where embryonic stem (ES) cells are induced to differentiate and organize as a prostate and bladder, respectively. Further, the ES cells can be driven by the correct embryonic mesenchymal cells to form epithelium that differentiates into secretory prostate glands and differentiated bladders that produce uroplakin. This requires the ES cells to mature into endoderm that gives rise to differentiated epithelium. This process is control by transcription factors in both the inductive mesenchymal cells (AR) and the responding epithelium (FoxA1 and Nkx3.1) that allows for organ development and differentiation. In this review, we explore a molecular mechanism where the pattern of transcription factor expression controls cell determination, where the cell is assigned a developmental fate and subsequently cell differentiation, and where the assigned cell now emerges with it's own unique character.

Estrogen receptor alpha mediates estrogen-inducible abnormalities in the developing penis

Previously, we reported an association between estrogen receptor-alpha (ERalpha) upregulation and detrimental effects of neonatal diethylstilbestrol (DES) exposure in the rat penis. The objective of this study was to employ the ERalpha knockout (ERalphaKO) mouse model to test the hypothesis that ERalpha mediates DES effects in the developing penis. ERalphaKO and wild-type C57BL/6 mice received oil or DES at a dose of 0.2 microg/pup per day (0.1 mg/kg) on alternate days from postnatal days 2 to 12. Fertility was tested at 80-240 days of age and tissues were examined at 96-255 days of age. DES caused malformation of the os penis, significant reductions in penile length, diameter, and weight, accumulation of fat cells in the corpora cavernosa penis, and significant reductions in weight of the bulbospongiosus and levator ani muscles in wild-type mice. Conversely, ERalphaKO mice treated with DES developed none of the above abnormalities. While nine out of ten male mice sired pups in the wild-type/control group, none did in the wild-type/DES group. ERalphaKO mice, despite normal penile development, are inherently infertile. Both plasma and intratesticular testosterone levels were unaltered in the DES-treated wild-type or DES-treated ERalphaKO mice when compared with controls, although testosterone concentration was much higher in the ERalphaKO mice. Hence, the resistance of ERalphaKO mice to developing penile abnormalities provides unequivocal evidence of an obligatory role for ERalpha in mediating the harmful effects of neonatal DES exposure in the developing penis.

The CAG repeat within the androgen receptor gene and its relationship to cryptorchidism

PURPOSE

We examined the significance of the CAG repeat polymorphism in the pathogenesis of cryptorchidism.

MATERIALS AND METHODS

Genomic deoxyribonucleic acid (DNA) was extracted from blood samples from 42 cryptorchid boys and from 31 non-cryptorchid control subjects. In the cryptorchid group, 7 had bilateral cryptorchidism and 6 had patent processus vaginalis in the contralateral side. To determine the number of CAG repeats, the DNA was amplified by polymerase chain reaction and sequenced.

RESULTS

The mean CAG repeat length in the AR gene was 22.5 (range 16 to 28) in patients and 21.5 (range 17 to 26) in controls (non-significant). Patients with bilateral cryptorchidism had a mean length of 24.3 (range 21 to 26) and patients with unilateral cryptorchidism and patent processus vaginalis in the contra lateral side had a mean of 25.2 (range 21 to 28), which was statistically different from controls (p = 0.015 and p = 0.005 respectively).

CONCLUSION

CAG repeat length of the AR gene does not seem to play a major role in patients with unilateral cryptorchidism. However, in patients with bilateral undescended testis, a less functional androgen receptor through a longer polyglutamine chain may have a role in its pathogenesis. In the same way, patients with unilateral cryptorchidism a contralateral patent processus vaginalis have longer CAG repeats that might be responsible for a slower testicular descent and incomplete closure of the processus vaginalis.

Morphological and immunohistochemical differences between gonadal maturation delay and early germ cell neoplasia in patients with undervirilization syndromes

CONTEXT

Maturation delay of germ cells and their progression into carcinoma in situ (CIS) frequently occurs in intersex patients. A developmentally delayed germ cell resembles a CIS cell and displays prolonged expression of immunohistochemical markers used for the diagnosis of CIS. This questions their applicability in young children.

OBJECTIVE

The objective of the study was the elaboration of tools to distinguish germ cells with maturation delay and CIS.

DESIGN

The design was a qualitative and quantitative analysis of the expression of diagnostic markers for CIS in gonads of young patients with undervirilization syndromes.

SETTING

The study was conducted in the pathology department of a university center, specializing in germ cell tumor pathogenesis.

PATIENTS

Fifty-eight formalin-fixed, paraffin-embedded testicular tissue samples of 30 undervirilized patients (1 month to 23 yr of age) were analyzed.

INTERVENTIONS

INTERVENTIONS included hematoxylin-eosin staining, immunohistochemistry for octamer binding transcription factor (OCT)3/4, gene encoding the stem cell factor receptor that has tyrosine kinase activity c-KIT, placental/germ alkaline phosphatase (PLAP), testis-specific protein Y encoded (TSPY), and VASA, double staining for OCT3/4 and VASA, with ploidy determination by fluorescent in situ hybridization.

MAIN OUTCOME MEASURE

Maturation delay and CIS are characterized by the staining patterns of the immunohistochemical markers.

RESULTS

CIS was diagnosed in three of 30 patients (10%) and four of 58 gonads (6.9%). Patient age, distribution of OCT3/4-positive cells throughout the gonad, and their position within the seminiferous tubule differ between maturation delay and CIS. Abnormal OCT3/4 and testis-specific protein Y encoded expression appear to be of pathogenetic relevance in the development of these lesions.

CONCLUSION

The dimorphic expression of OCT3/4 allows distinction between maturation delay and CIS. Studies in larger patient series are essential before a biopsy to evaluate the neoplastic risk can eventually be proposed as an alternative for gonadectomy.

Complete Androgen Insensitivity Syndrome: The Role of the Endocrine Surgeon

Androgen insensitivity syndrome (AIS) is an X-linked recessive disorder characterized by varying degrees of feminization secondary to androgen receptor insensitivity. We report a case of a 34-year-old female with complete androgen insensitivity who presented with a history of primary amenorrhea and two intra-abdominal gonads found on CT scan. The patient underwent successful laparoscopic bilateral gonadectomy without complications. AIS is present in 1:20,000 to 64,000 males; complete androgen insensitivity is seen in 2–5:100,000 phenotypic females and should therefore be considered in any otherwise healthy female with abnormal pubertal development and infertility. Although controversial, most endocrinologists agree that gonadectomy may be performed after puberty with minimal risk of testicular neoplasm.

Androgen-regulated transcripts in the neonatal mouse testis as determined through microarray analysis

Androgens are required for normal spermatogenesis in mammalian testes. These hormones directly regulate testicular somatic cells that, in turn, support germ cell differentiation. However, the identity of genes under androgen regulation in the testis are not well known. In the present study, neonatal male mice (8 days postpartum) treated by testosterone propionate (TP) were used to study androgen action in the testis as evidenced by alterations in gene expression. Mice were treated with 0.5 mg of TP or dihydrotestosterone (DHT) or vehicle (oil), and testes were harvested 4, 8, and 16 h after treatment. Global gene expression was monitored by microarray analysis. Real-time reverse transcription-polymerase chain reaction was performed to confirm the microarray results. The methodology was verified by confirming the presence of previously characterized TP-regulated genes, including Pem in Sertoli cells and Cyp17a1 in Leydig cells. No significant differences in gene expression were found between TP- and DHT-treated samples. Microarray analysis identified 141, 119, and 109 up-regulated genes at 4, 8 and 16 h after TP treatment, respectively, and 83, 99, and 111 down-regulated genes at the same corresponding time points. The androgen regulation of the selected gene was verified further using testes from flutamide-treated adult mice and isolated Sertoli cells in culture. The data generated in the present study may serve as a foundation for hypothesis-driven research and provide insights regarding gene networks and pathways under androgen control in the testis.

ATRX and sex differentiation

Most interest in the gene encoding the alpha-thalassemia, mental retardation, X-linked protein (ATRX) has traditionally been focused on its role in brain development and globin regulation. However, mutations in the ATRX gene also cause varying degrees of gonadal and urogenital abnormalities. These range from small testes to ambiguous external genitalia in XY individuals. ATRX is of great interest because this very large protein is one of the least understood proteins involved in mammalian sexual development. Although the biochemical role of ATRX remains unknown, recent and emerging evidence implicates ATRX in chromatin remodeling. We review what is known about ATRX as a chromatin remodeling protein, and its role in mammalian sex differentiation.

Anatomical Studies of the Fibroblast Growth Factor-10 Mutant, Sonic Hedge Hog Mutant and Androgen Receptor Mutant Mouse Genital Tubercle

OBJECTIVES

Congenital genital abnormalities have a diverse spectrum from hypospadias to cloacal anomalies. The molecular events in the normal and abnormal development of the genital tubercle (GT) are still obscure. Genetically engineered mice with specific gene deletions that affect genital anatomy are a useful tool to better understand the etiology of genital abnormalities. In this study, we compared the genital tubercle anatomy of the androgen receptor (AR) deficient, fibroblastic growth factor (FGF)-10 deficient and Sonic HedgeHog (Shh) deficient mutant male mice to that of the wild type male and female mouse.

MATERIALS AND METHODS

The lower pelvis of the androgen receptor deficient, FGF-10 deficient, Shh deficient mutant male and wild type male and female mouse at different gestational days (E13-21) and post natal ages (1 day-1 week) were studied. GTs were imaged, serially sectioned and stained immunohistochemically with antibodies raised against E-Cadherin, Cytokeratin 7, 10 and 14. Serial sections of the GTs were selected and three-dimensional computerized images were created to better elucidate the anatomy.

RESULTS

AR deficient mutant male mouse revealed a distinctive GT anatomy, different from both sexes. The corporal bodies and glans remained hypoplastic whereas the urethral spongiosa was more developed than the wild type female counterpart. This finding is consistent with the AR mutant mouse being a unique morphologic phenotype distinct from the normal male and female. FGF-10 deficient mutant male mouse revealed normal corporal bodies with failure of the urethral plate to fuse ventrally consistent with hypospadias. The Shh deficient mutant mouse demonstrated complete agenesis of GT outgrowth and a persistent cloaca.

CONCLUSION

Animal models bred by gene knockout technology or natural occurring mutants contribute to the basic understanding of normal and abnormal GT development. The anatomy of the these three mutant mice confirms the importance of the androgen receptor, FGF-10 and Shh in genital development.

Ligand activation of the androgen receptor downregulates E-cadherin-mediated cell adhesion and promotes apoptosis of prostatic cancer cells

Androgen independence is the major cause of endocrine therapy failure in advanced prostate cancer (PC). To examine the effects of human androgen receptor (AR) expression on growth of human PC cells, transfection of full-length AR cDNA in an androgen-insensitive human prostatic adenocarcinoma cell line (DU145) was performed. Transcriptional activity of AR was confirmed by the MMTV luciferase assay and AR expression was assessed by reverse transcriptase polymerase chain reaction, Western blotting, and immunocytochemistry. Two stable transfectant cell lines expressing functional AR were established and passaged over 60 times. Under standard culture conditions, AR expression in transfected cells was predominantly cytoplasmic. Exposure to dihydrotestosterone (DHT; 60 pM-10 nM) resulted in a rapid (maximal at 30 minutes) translocation of AR to the nucleus. Treatment with DHT (5 nM) caused a significant reduction in cell-cell adhesion and aggregation accompanied by a decrease in E-cadherin expression. This was associated with up to 40% inhibition of proliferation and approximately two-fold increase in apoptosis. These results suggest that gene transfer-mediated AR expression in DU145 cells confers sensitivity to DHT, modulates cell-cell adhesion through E-cadherin, and suppresses cell growth by inhibiting proliferation and promoting apoptosis. This provides amodelfor studies ofAR-regulated cell signalling and identification of novel androgen-regulated genes in PC.

Absence of Y chromosome microdeletions involving the DAZ (deleted in azoospermia) and RBM (ribonucleic acid-binding motif) genes in patients with chordee without hypospadias

The presence or absence of 33 DNA loci was investigated with a focus on the long arm of Y chromosome (Yq) interval 6 involving the DAZ and RBM genes, by means of a polymerase chain reaction strategy, in 10 patients with hypospadias. All patients did not show any of the 33 DNA loci. It would appear that chordee without hypospadias does not involve interval 6 of the Y chromosome.

Insights into causes of sexual ambiguity

Our understanding of the causes of sexual ambiguity has progressed from the determination of the hormonal etiologies to defining the genetic basis of intersex disorders. The localization of specific genes involved in the process of sexual differentiation has made it possible to determine the mutations and other molecular events that result in sexual ambiguity. With this information, some disorders can now be diagnosed before birth and possibly even treated in utero.

Androgen insensitivity syndrome: an immunohistochemical, ultrastructural, and morphometric study

OBJECTIVE

To evaluate the morphometric, immunohistochemical, and ultrastructural lesions of the testes in prepubertal and adult patients with androgen insensitivity syndrome.

METHODS

We examined the testicular biopsy using immunohistochemistry for vimentin, smooth muscle actin, and collagen IV antigens. Quantification of seminiferous tubules and testicular interstitium was performed in prepubertal and adult patients with androgen insensitivity syndrome and results were compared with normal testes from both infants and adults.

RESULTS

The adult testes presented nodular and diffuse lesions that consisted of Sertoli-cell-only seminiferous tubules. Two types of Sertoli cells could be distinguished, namely, immature vimentin-positive Sertoli cells and nearly mature Sertoli cells. In the nodules, the lamina propria was thin and contained a scant number of actin-positive peritubular cells. Leydig cells were hyperplastic. The prepubertal patients showed only diffuse lesions characterized by Sertoli cell hyperplasia, decreased germ cell numbers, and a discontinuous immunoreaction to collagen IV.

CONCLUSIONS

The testicular lesions in androgen insensitivity syndrome are probably caused by primary alterations that begin during gestation. These lesions become progressively more pronounced at puberty, when the nodular lesion pattern (adenomas) is completely developed.

Bladder tumor markers: need, nature and application. 2. Tumor and tumor-associated antigens

Despite the diversity of the available markers, none is truly specific to transitional epithelium, let alone its tumors. Some of the markers used, such as hCG and CEA, are far better known in other fields and seem to be expressed in only a minority of urothelial tumors. The majority of the available markers are tumor associated and should perhaps be considered as by-products of the process of malignancy in the urinary tract. Newer tests which are simple, rapid and easy to use have a practical advantage. These are currently the Bard BTA, BTA Stat and Aura-Tek FDP tests. So far, these markers have achieved only an arguable and marginal role in daily clinical practice, challenging the role of cytology and helping decide the type of cystoscopy. A more substantial role awaits a test with higher and more consistent sensitivity and specificity, together with the capability to provide independent diagnostic and/or prognostic information. In this part of the review we examine the literature view of the above-mentioned tests, as well as other new and some older tests such as blood group-related antigens, Lewis antigen, cytokeratins and others.

Androgen receptor gene alterations are not associated with isolated cryptorchidism

PURPOSE

Multiple theories of testicular descent exist but there is no consensus. Cryptorchidism is a component of the androgen insensitivity syndrome, suggesting that testicular descent may be at least partially under the control of androgenic stimulation. To determine whether isolated cryptorchidism may be caused by androgen insensitivity, we screened a population of boys with isolated cryptorchidism for the presence of androgen receptor gene alterations.

MATERIALS AND METHODS

Deoxyribonucleic acid (DNA) was isolated from tissue collected from 21 patients with isolated cryptorchidism during orchiopexy. Patient selection was biased to maximize the likelihood of detection of a genetic etiology of cryptorchidism. The DNA was screened for androgen receptor gene alterations in exons 2 to 8 using single strand conformational polymorphism analysis.

RESULTS

No abnormalities in the androgen receptor gene were detected by single strand conformational polymorphism analysis in any patient.

CONCLUSIONS

Mutations of the androgen receptor gene in the hormone and DNA binding domains of the protein appear to be an unlikely cause of isolated cryptorchidism.