In situ hybridization assay of androgen receptor gene in hepatocarcinogenesis

AIM To determine the correlation between expression of androgen receptor (AR) gene and hepatocarcinogenesis. METHODS Male SD rats were used as experimental animals and the animal model of experimental hepatocarcinoma was established by means of 3′ me DAB administration. Androgen receptor mRNA was detected by a non radioactive in situ hybridization assay in neoplastic and non neoplastic liver tissues. RESULTS The expression of androgen receptor mRNA was observed only in neoplastic cells and some atypical hyperplastic cells. In the liver tissue of control animal and the remaining normal liver cells adjacent to the carcinoma tissue, no positive signal was seen. CONCLUSION Androgen has an important correlation with hepatocarcinogenesis and the expression of androgen receptor gene might be a mark event during hepatocarcinogenesis.

Reduced mesencephalic astrocyte-derived neurotrophic factor expression by mutant androgen receptor contributes to neurodegeneration in a model of spinal and bulbar muscular atrophy pathology

Spinal and bulbar muscular atrophy is a neurodegenerative disease caused by extended CAG trinucleotide repeats in the androgen receptor gene,which encodes a ligand-dependent transcription facto r.The mutant androgen receptor protein,characterized by polyglutamine expansion,is prone to misfolding and forms aggregates in both the nucleus and cytoplasm in the brain in spinal and bulbar muscular atrophy patients.These aggregates alter protein-protein interactions and compromise transcriptional activity.In this study,we reported that in both cultured N2a cells and mouse brain,mutant androgen receptor with polyglutamine expansion causes reduced expression of mesencephalic astrocyte-de rived neurotrophic factor.Overexpressio n of mesencephalic astrocyte-derived neurotrophic factor amelio rated the neurotoxicity of mutant androgen receptor through the inhibition of mutant androgen receptor aggregation.Conversely.knocking down endogenous mesencephalic astrocyte-derived neurotrophic factor in the mouse brain exacerbated neuronal damage and mutant androgen receptor aggregation.Our findings suggest that inhibition of mesencephalic astrocyte-derived neurotrophic factor expression by mutant androgen receptor is a potential mechanism underlying neurodegeneration in spinal and bulbar muscular atrophy.

Androgen signaling inhibits de novo lipogenesis to alleviate lipid deposition in zebrafish

Testosterone is closely associated with lipid metabolism and known to affect body fat composition and muscle mass in males.However,the mechanisms by which testosterone acts on lipid metabolism are not yet fully understood,especially in teleosts.In this study,cyp17a1-/-zebrafish(Danio rerio)exhibited excessive visceral adipose tissue(VAT),lipid content,and up-regulated expression and activity of hepatic de novo lipogenesis(DNL)enzymes.The assay for transposase accessible chromatinwithsequencing(ATAC-seq)results demonstrated that chromatin accessibility of DNL genes was increased in cyp17a1-/-fish compared to cyp17a1+/+male fish,including stearoyl-CoA desaturase(scd)and fatty acid synthase(fasn).Androgen response element(ARE)motifs in the androgen signaling pathway were significantly enriched in cyp17a1+/+male fish but not in cyp17a1-/-fish.Both androgen receptor(ar)-/-and wildtype(WT)zebrafish administered with Ar antagonist flutamide displayed excessive visceral adipose tissue,lipid content,and up-regulated expression and activity of hepatic de novo lipogenesis enzymes.The Ar agonist BMS-564929 reduced the content of VAT and lipid content,and down-regulated acetyl-CoA carboxylase a(acaca),fasn,and scd expression.Mechanistically,the rescue effect of testosterone on cyp17a1-/-fish in terms of phenotypes was abolished when ar was additionally depleted.Collectively,these findings reveal that testosterone inhibits lipid deposition by down-regulating DNL genes via Ar in zebrafish,thus expanding our understanding of the relationship between testosterone and lipid metabolism in teleosts.

Phenotypic heterogeneity of mutations in androgen receptor gene

Androgen receptor （AR） gene has been extensively studied in diverse clinical conditions. In addition to the point mutations, trinucleotide repeat （CAG and GGN） length polymorphisms have been an additional subject of interest and controversy among geneticists. The polymorphic variations in triplet repeats have been associated with a number of disorders, but at the same time contradictory findings have also been reported. Further, studies on the same disorder in different populations have generated different results. Therefore, combined analysis or review of the published studies has been of much value to extract information on the significance of variations in the gene in various clinical conditions. AR genetics has been reviewed extensively but until now review articles have focused on individual clinical categories such as androgen insensitivity, male infertility, prostate cancer, and so on. We have made the first effort to review most the aspects of AR genetics. The impact of androgens in various disorders and polymorphic variations in the AR gene is the main focus of this review. Additionally, the correlations observed in various studies have been discussed in the light of in vitro evidences available for the effect of AR gene variations on the action of androgens.

Androgen receptor signaling and mutations in prostate cancer

Normal and neoplastic growth of the prostate gland are dependent on androgen receptor （AR） expression and function. Androgenic activation of the AR, in association with its coregulatory factors, is the classical pathway that leads to transcriptional activity of AR target genes. Alternatively, cytoplasmic signaling crosstalk of AR by growth factors, neurotrophic peptides, cytokines or nonandrogenic hormones may have important roles in prostate carcinogenesis and in metastatic or androgen-independent （AI） progression of the disease. In addition, cross-modulation by various nuclear transcription factors acting through basal transcriptional machinery could positively or negatively affect the AR or AR target genes expression and activity. Androgen ablation leads to an initial favorable response in a significant number of patients; however, almost invariably patients relapse with an aggressive form of the disease known as castration-resistant or hormone-refractory prostate cancer （PCa）. Understanding critical molecular events that lead PCa cells to resist androgen-deprivation therapy is essential in developing successful treatments for hormone-refractory disease. In a significant number of hormone-refractory patients, the AR is overexpressed, mutated or genomically amplified. These genetic alterations maintain an active presence for a highly sensitive AR, which is responsive to androgens, antiandrogens or nonandrogenic hormones and collectively confer a selective growth advantage to PCa cells. This review provides a brief synopsis of the AR structure, AR coregulators, posttranslational modifications of AR, duality of AR function in prostate epithelial and stromal cells, AR-dependent signaling, genetic changes in the form of somatic and germline mutations and their known functional significance in PCa cells and tissues.

nfluence of immune inflammation on androgen receptor expression in benign prostatic hyperplasia tissue

This study was designed to investigate the association between immune inflammation and androgen receptor （AR） expression in benign prostatic hyperplasia （BPH）. We retrospectively analyzed 105 prostatectomy specimens. An immune inflammation score for each specimen was defined by combining three immunohistochemical markers （CD4, CD8 and CD20）. The immunohistochemical markers were CD4 and CD8 for T lymphocytes, CD20 for B lymphocytes and AR antibody for the AR in BPH samples. Rates of CD4, CD8, CD20 and AR expression in BPH were 20 （19.0%）, 21 （20.0%）, 101 （96.2%） and 48 （45.7%）, respectively. Total prostate volume （TPV） was higher in the immune inflammation group than in the non-immune inflammation group （62.7 ml vs. 49.2 ml, t=-2.482, P〈0.05）. Patients in the immune inflammation group had a higher serum prostate-specific antigen （PSA） than those in the non-inflammation group （7.5 ng m1-1 vs. 5.4 ng m1-1, t=-2.771, P〈0.05）. Specifically, the immune inflammation group showed a higher rate of AR expression than the non-inflammation group （56.1% vs. 28.2%, χ2=7.665, P〈0.05）. Our study revealed a strong association between immune inflammation and TPV, serum PSA and AR expression in BPH tissue. Prostate hyperplasia caused by an immune inflammatory process may contribute to BPH progression over time. Therefore, the inflammatory response involved in BPH may be a prime therapeutic target.

Androgen receptor signaling in hepatocellular carcinoma and pancreatic cancers

Hepatocellular carcinoma (HCC) and pancreatic cancer remain difficult to treat, and despite the ongoing development of new treatments, the overall survival rate has only modestly improved over the past decade. Liver and pancreatic progenitors commonly develop from endoderm cells in the embryonic foregut. A previous study showed that HCC and pancreatic cancer cell lines variably express androgen receptor (AR), and these cancers and the surrounding tissues also express AR. AR is a ligand-dependent transcription factor that belongs to the nuclear receptor superfamily. Androgen response element is present in regulatory elements on the AR-responsive target genes, such as transforming growth factor beta-1 (TGF beta-1) and vascular endothelial growth factor (VEGF). It is well known that the activation of AR is associated with human carcinogenesis in prostate cancer as well as HCC and pancreatic cancer and that GRP78, TGF beta, and VEGF all play important roles in carcinogenesis and cancer development in these cancers. HCC is a male-dominant cancer irrespective of its etiology. Previous work has reported that vertebrae forkhead box A 1/2 are involved in estrogen receptors and/or AR signaling pathways, which may contribute to the gender differences observed with HCC. Our recent work also showed that AR has a critical role in pancreatic cancer development, despite pancreatic cancer not being a male dominant cancer. Aryl hydrocarbon (or dioxin) receptor is also involved in both HCC and pancreatic cancer through the formation of complex with AR. It is possible that AR might be involved in their carcinogenesis through major histocompatibility complex class I chain-related gene A/B. This review article describes AR and its role in HCC and pancreatic cancer and suggests that more specific AR signaling-inhibitors may be useful in the treatment of these “difficult to treat” cancers.

Human androgen deficiency： insights gained from androgen receptor knockout mouse models

The mechanism of androgen action is complex. Recently, significant advances have been made into our understanding of how androgens act via the androgen receptor （AR） through the use of genetically modified mouse models. A number of global and tissue-specific AR knockout （ARKO） models have been generated using the Cre-loxP system which allows tissue- and/or cell-specific deletion. These ARKO models have examined a number of sites of androgen action including the cardiovascular system, the immune and hemopoetic system, bone, muscle, adipose tissue, the prostate and the brain. This review focuses on the insights that have been gained into human androgen deficiency through the use of ARKO mouse models at each of these sites of action, and highlights the strengths and limitations of these Cre-loxP mouse models that should be considered to ensure accurate interpretation of the phenotype.

Androgen receptor isoforms in human and rat prostate

Aim: To investigate the androgen receptor (AR) isoforms and its variability of expression in human and rat prostatictissues. Methods: Human benign prostatic hyperplasia (BPH) and prostatic cancer tissues were obtained from pa-tients undergoing prostatectomy, and rat ventral prostate was incised 3 days after castration. Forty-one AR-positive BPHspecimens, 3 prostatic cancer specimens, and 6 rat prostates were used. After processing at 4℃, the tissues were ex-amined by means of high resolution isoelectric focusing (IEF) technique to determine their AR isoforms. Results:From the prostatic specimens, 3 types of AR isoforms were detected with pI values at 6.5, 6.0, and 5.3. In humanBPH tissues, 15/41 (36.6%) specimens showed all the three types of isoforms, while 19/41 (46.3%) showed 2 iso-fora at various combinations and 7/41 (17.1%), 1 isoform. For the 3 prostatic cancer specimens, one showed 3 iso-forms, one, 2 isoforms, and the other failed to show any isoform. All rat prostatic tissues showed 2 isoforms at differ-ent combinations. Binding of ~3H-dihydrotestosterone (DHT) to the isoforms was inhibited by the addition of 100-foldexcess of DHT or testosterone, but not progesterone, oestradiol or diethylstilboestrol. Conclusion: AR isoforms aredifferent in different patients. Although their genesis is not clear, the therapeutic implication of the present observationappears to be interesting, that may help clarifying the individual differences in the response to hormonal therapy.(Asian J Androl 2000 Dec; 2: 307-310)

dentification of testosterone-/androgen receptor-regulated genes in mouse Sertoli cells

Androgen and androgen receptor （AR） play important roles in male spermatogenesis and fertility, yet detailed androgen/AR signals in Sertoli cells remain unclear. To identify AR target genes in Sertoli cells, we analyzed the gene expression profiles of testis between mice lacking AR in Sertoli cells （S-AR-/y） and their littermate wild-type （WT） mice. Digital gene expression analysis identified 2276 genes downregulated and 2865 genes upregulated in the S-AR-/y mice testis compared to WT ones. To further nail down the difference within Sertoli cells, we first constructed Sertoli cell line TM4 with stably transfected AR （named as TM4/AR） and found androgens failed to transactivate AR in Sertoli TM4 and TM4/AR cells. Interestingly, additional transient transfection of AR-cDNA resulted in significant androgen responsiveness with TM4/AR cells showing 10 times more androgen sensitivity than TM4 cells. In the condition where maximal androgen response was demonstrated, we then analyzed gene expression and found the expression levels of 2313 genes were changed more than twofold by transient transfection of AR-cDNA in the presence of testosterone. Among these genes, 603 androgen-/ AR-regulated genes, including 164 upregulated and 439 downregulated, were found in both S-AR-/y mice testis and TM4/AR cells. Using informatics analysis, the gene ontology was applied to analyze these androgen-/AR-regulated genes to predict the potential roles of androgen/AR in the process of spermatogenesis. Together, using gene analysis in both S-AR-/y mice testis and TM4/AR cells may help us to better understand the androeen/AR signals in Sertoli cells and their influences in spermatogenesis.

Chimeric molecules facilitate the degradation of androgen receptors and repress the growth of LNCaP cells

Post-translational degradation of protein plays an important role in cell life. We employed chimeric molecules （dihydrotestosterone-based proteolysis-targeting chimeric molecule [DHT-PROTAC]） to facilitate androgen receptor （AR） degradation via the ubiquitin-proteasome pathway （UPP） and to investigate the role of AR in cell proliferation and viability in androgen-sensitive prostate cancer cells. Western blot analysis and immunohistochemistry were applied to analyse AR levels in LNCaP cells after DHT-PROTAC treatment. Cell counting and the 3-（4,5-dimethylthiazol-2-yl）-2,5- diphenyl tetrazolium bromide （MTT） cell viability assay were used to evaluate cell proliferation and viability after AR elimination in both LNCaP and PC-3 cells. AR was tagged for elimination via the UPP by DHT-PROTAC, and this could be blocked by proteasome inhibitors. Degradation of AR depended on DHT-PROTAC concentration, and either DHT or an ALAPYIP-（arg）8 peptide could compete with DHT-PROTAC. Inhibition of cell proliferation and decreased viability were observed in LNCaP cells, but not in PC-3 or 786-0 cells after DHT-PROTAC treatment. These data indicate that AR elimination is facilitated via the UPP by DHT-PROTAC, and that the growth of LNCaP cells is repressed after AR degradation.

The role of the androgen receptor in prostate development and benign prostatic hyperplasia:A review

Benign prostatic hyperplasia(BPH)is a benign enlargement of the prostate in which incidence increases linearly with age,beginning at about 50 years old.BPH is a significant source of morbidity in aging men by causing lower urinary tract symptoms and acute urinary retention.Unfortunately,the etiology of BPH incidence and progression is not clear.This review highlights the role of the androgen receptor(AR)in prostate development and the evidence for its involvement in BPH.The AR is essential for normal prostate development,and individuals with defective AR signaling,such as after castration,do not experience prostate enlargement with age.Furthermore,decreasing dihydrotestosterone availability through therapeutic targeting with 5a-reductase inhibitors diminishes AR activity and results in reduced prostate size and symptoms in some BPH patients.While there is some evidence that AR expression is elevated in certain cellular compartments,how exactly AR is involved in BPH progression has yet to be elucidated.It is possible that AR signaling within stromal cells alters intercellular signaling and a“reawakening”of the embryonic mesenchyme,loss of epithelial AR leads to changes in paracrine signaling interactions,and/or chronic inflammation aids in stromal or epithelial proliferation evident in BPH.Unfortunately,a subset of patients fails to respond to current medical approaches,forcing surgical treatment even though age or associated co-morbidities make surgery less attractive.Fundamentally,new therapeutic approaches to treat BPH are not currently forthcoming,so a more complete molecular understanding of BPH etiology is necessary to identify new treatment options.

Sex Hormones and Androgen Receptor:Risk Factors of Coronary Heart Disease in Elderly Men

Objective To investigate the variation of sex hormone and its receptor level in elderly male patients with coronary heart disease (CHD) and to evaluate the correlations between CHD and sex hormone as well as sex hormone receptor. Methods Altogether 139 male CHD patients (CHD group) aged 60-92 years and 400 healthy men (control group) aged 60-90 years were included in this cross sectional study. The plasma concentrations of dehydroepiandrosterone sulfate (DHEAS),total testosterone (TT),free testosterone (FT),estradiol (E2),sex hormone binding globulin (SHBG),luteinizing hormone (LH),and follicle-stimulating hormone (FSH) were measured. The androgen receptor (AR) was tested by flow cytometry. Correlations between CHD and levels of sex hormones and AR were analyzed. Results Compared with the control group,the levels of DHEAS,TT,FT,SHBG,and the fluorescence intensity of AR in the CHD group significantly reduced (P<0.05),while the levels of FSH and E2 significantly increased (P<0.01). Age was negatively correlated with TT (r=-0.28,P=0.00) and FT (r=-0.17,P=0.01),while it was positively correlated with SHBG (r=0.14,P=0.04) and E2 (r=0.33,P=0.00). AR fluorescence intensity was negatively correlated with systolic blood pressure (r=-0.12,P=0.01). Binary logistic regression analysis showed that TT,SHBG,and AR were all negatively correlated with CHD (P<0.05). Conclusions Elderly male patients with CHD are found to have low levels of DHEAS,TT,FT,SHBG,and AR,while high concentrations of E2 and FSH. Low levels of TT and SHBG may be the potential risk factors of CHD in elderly men.

Androgen receptors are expressed in a variety of human fetal extragenital tissues： an immunohistochemical study

Aim： To investigate the expression of androgen receptors in the extragenital tissues of developing human embryo. Methods： Using immunohistochemistry, we investigated the distribution of androgen receptor （AR） in the extragenital tissues of paraffin-embedded tissue sections of first trimester （8-12 weeks gestation） human embryos. Gender was determined by polymerized chain reaction. Results： There were no differences in the expression and distribution of AR in male and female embryos at any stage of gestation. AR expression was seen in the thymus gland. The bronchial epithelium of the lungs showed intense positive staining with surrounding stroma negative. Furthermore, positive staining for androgen receptor was exhibited in the spinal cord with a few positive cells in the surrounding tissues. Cardiac valves also showed strong positive staining but with faint reactivity of the surrounding cardiac muscle. There was no staining in kidney, adrenal, liver or bowel. Conclusion： This study demonstrates that immunoreactive AR protein is present in a wide variety of human first trimester fetal tissues and shows the potential for androgen affecting tissues, which are mostly not considered to be androgen dependent. Moreover, it implies that androgen might act as atrophic factor and affect the early development of these organs rather than simply sexual differentiation.

Localization and potential function of androgen receptor in rat salivary gland

Aim： To investigate the localization and quantity of androgen receptor （AR） in the salivary glands of rats with further analysis on the effect of castration. Methods： Sixty male Wistar rats, aged 30-60 days, were randomly divided into three groups （castrated, sham-operated and normal controls） with 20 rats in each group. The rats in the castrated group were castrated and the submaxillary glands were removed after 1 week. The salivary glands of the rats in the sham-operated and the normal control groups were also removed. Parts of the salivary glands were fixed for immuohistochemistry and in situ hybridization assays. Other parts were used for Western blot. Results： AR immunoreactivity in the three groups was localized in the glandular epithelial cells of the serous acinus and the glandular duct of the salivary gland, mainly in the nuclei. AR mRNA hybridization signals in the salivary glands of the castrated group were mainly distributed in the epithelial cells of the convoluted and secretary ducts; AR mRNA in the sham-operated and the normal control groups were found in the epithelial cells of the convoluted, the secretary and the excretory ducts. The quantity of AR in the salivary glands was decreased significantly in the castrated rats compared with the sham-operated and the normal controls. Moreover, epidermal growth factor （EGF） secreted by the salivary glands was also decreased in the castrated rats. Conclusion： Castration appears to affect the production of AR in the salivary gland and the distribution of the AR mRNA and could further affect the function of the salivary gland. The changes of AR and the distribution of AR mRNA may play an important role in the interactions between the testes and the salivary gland. （Asian J Androl 2005 Sep; 7： 295-301）

Novel mutation in the ligand-binding domain of the androgen receptor gene （1790p） associated with complete androgen insensitivity syndrome

Mutations in the X-linked androgen receptor （AR） gene cause androgen insensitivity syndrome （AIS）, resulting in an impaired embryonic sex differentiation in 46,XY genetic men. Complete androgen insensitivity （CAIS） produces a female external phenotype, whereas cases with partial androgen insensitivity （PALS） have various ambiguities of the genitalia. Mild androgen insensitivity （MAIS） is characterized by undermasculinization and gynecomastia. Here we describe a 2-month-old 46,XY female patient, with all of the characteristics of CAIS. Defects in testosterone （T） and dihydrotestosterone （DHT） synthesis were excluded. Sequencing of the AR gene showed the presence in exon 6 of a T to C transition in the second base of codon 790, nucleotide position 2369, causing a novel missense Leu790Pro mutation in the ligand-binding domain of the AR protein. The identification of a novel AR mutation in a girl with CAIS provides significant information due to the importance of missense mutations in the ligand-binding domain of the AR, which are able to induce functional abnormalities in the androgen binding capability, stabilization of active conformation, or interaction with coactivators.

The androgen receptor in hormone-refractory prostate cancer

Advanced prostate cancer is responsive to hormone therapy that interferes with androgen receptor （AR） signalling. However, the effect is short-lived, as nearly all tumours progress to a hormone-refractory （HR） state, a lethal stage of the disease. Intuitively, the AR should not be involved because hormone therapy that blocks or reduces AR activity is not effective in treating HR tumours. However, there is still a consensus that AR plays an essential role in HR prostate cancer （HRPC） because AR signalling is still functional in HR tumours. AR signalling can be activated in HR tumours through several mechanisms. First, activation of intracellular signal transduction pathways can sensitize the AR to castrate levels of androgens. Also, mutations in the AR can change AR ligand specificity, thereby allowing it to be activated by non-steroids or anti-androgens. Finally, overexpression of the wild-type AR sensitizes itself to low concentrations of androgens. Therefore, drugs targeting AR signalling could still be effective in treating HRPC.

Posttranslational regulation of androgen dependent and independent androgen receptor activities in prostate cancer

Prostate cancer(PCa)is the most commonly diagnosed cancer among men in western countries.Androgen receptor(AR)signaling plays key roles in the development of PCa.Androgen deprivation therapy(ADT)remains the standard therapy for advanced PCa.In addition to its ligand androgen,accumulating evidence indicates that posttranscriptional modification is another important mechanism to regulate AR activities during the progression of PCa,especially in castration resistant prostate cancer(CRPC).To date,a number of posttranscriptional modifications of AR have been identified,including phosphorylation(e.g.by CDK1),acetylation(e.g.by p300 and recognized by BRD4),methylation(e.g.by EZH2),ubiquitination(e.g.by SPOP),and SUMOylation(e.g.by PIAS1).These modifications are essential for the maintenance of protein stability,nuclear localization and transcriptional activity of AR.This review summarizes posttranslational modifications that influence androgen-dependent and-independent activities of AR,PCa progression and therapy resistance.We further emphasize that in addition to androgen,posttranslational modification is another important way to regulate AR activity,suggesting that targeting AR posttranslational modifications,such as proteolysis targeting chimeras(PROTACs)of AR,represents a potential and promising alternate for effective treatment of CRPC.Potential areas to be investigated in the future in the field of AR posttranslational modifications are also discussed.

Androgen receptor expression in clinically localized prostate cancer： immunohistochemistry study and literature review

Aim： To evaluate androgen receptor （AR） expression in clinically localized prostate cancer （PCa）. Methods： Specimens were studied from 232 patients who underwent radical prostatectomy for clinically localized prostatic adenocarcinoma without neoadjuvant hormonal therapy or chemotherapy at our institution between November 2001 and June 2005. Immunohistochemical study was performed using an anti-human AR monoclonal antibody AR441. The mean AR density in the hot spots of different histological areas within the same sections were compared and the correlation of malignant epithelial AR density with clinicopathological parameters such as Gleason score, tumor, nodes and metastases （TNM） stage and pre-treatment prostate-specific antigen （PSA） value was assessed. Results： AR immunoreactivity was almost exclusively nuclear and was observed in tumor cells, non-neoplastic glandular epithelial cells and a proportion of peritumoral and interglandular stromal cells. Mean percentage of AR-positive epithelial cells was significantly higher in cancer tissues than that in normal prostate tissues （mean e SD, 90.0% ± 9.3% vs. 85.3% ±9.7%, P 〈 0.001）. The histological score yielded similar results. The percentage ofAR immunoreactive prostatic cancer nuclei and histological score were not correlated with existing parameters such as Gleason score, tumor, nodes and metastases stage and pre-treatment PSA value in this surgically treated cohort. Conclusion： The results of the present study suggest that there may be limited clinical use for determining AR expression （if evaluated in hot spots） in men with localized PCa.

Expression of androgen receptor target genes in skeletal muscle

We aimed to determine the mechanisms of the anabolic actions of androgens in skeletal muscle by investigating potential androgen receptor （AR）-regulated genes in in vitro and in vivo models. The expression of the myogenic regulatory factor myogenin was significantly decreased in skeletal muscle from testosterone-treated orchidectomized male mice compared to control orchidectomized males, and was increased in muscle from male AR knockout mice that lacked DNA binding activity （AR△ZF2） versus wildtype mice, demonstrating that myogenin is repressed by the androgen/AR pathway. The ubiquitin ligase Fbxo32 was repressed by 12 h dihydrotestosterone treatment in human skeletal muscle cell myoblasts, and c-Myc expression was decreased in testosterone-treated orchidectomized male muscle compared to control orchidectomized male muscle, and increased in AR△ZF2 muscle. The expression of a group of genes that regulate the transition from myoblast proliferation to differentiation, Tceal7, p57Kip2, IEf2 and calcineurin Aa, was increased in AR△ZF2 muscle, and the expression of all but p57kip2 was also decreased in testosterone-treated orchidectomized male muscle compared to control orchidectomized male muscle. We conclude that in males, androgens act via the AR in part to promote peak muscle mass by maintaining myoblasts in the proliferative state and delaying the transition to differentiation during muscle growth and development, and by suppressing ubiquitin ligase-mediated atrophy pathways to preserve muscle mass in adult muscle.